Condition

Cognitive Improvement

Cognitive improvement means sharpening normal brain function, including memory, attention and processing speed. Caffeine with L-theanine, as in tea, has the strongest evidence, and a review of trials found reaction time improved. That rests on one small study of 88 people, though, and evidence for other options, such as phosphatidylserine, is limited.

Sources: PMID 40314930

Supplements studied: 55
Graded outcomes: 57
Trials: 161
People studied: 28,654

Evidence by supplement

Strong
Moderate
Limited
Very limited

55 supplements

Tea (Camellia sinensis)

Tea (Camellia sinensis): outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People
	Reaction Time Moderate Improvement	Improves (the measure goes up)	Moderate effect	1 study	88 people
Studies that measured reaction time Effects of Tea (Camellia sinensis) or its Bioactive Compounds l-Theanine or l-Theanine plus Caffeine on Cognition, Sleep, and Mood in Healthy Participants: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.Nutr Rev · PMID 40314930
	Attention Small Improvement	Improves (the measure goes up)	Small effect		4 people

Piracetam

Piracetam: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People
	Cognitive Decline Moderate Improvement	Improves (the measure goes down)	Moderate effect	5 studies	213 people
Studies that measured cognitive decline [On the dose-effect relationship in the therapy with piracetam (author's transl)]Arzneimittelforschung · PMID 786310 Drug therapy and memory training programs: a double-blind randomized trial of general practice patients with age-associated memory impairmentInt Psychogeriatr · PMID 7865703 Clinical efficacy of piracetam in cognitive impairment: a meta-analysisDement Geriatr Cogn Disord · PMID 12006732 and 2 more on the Piracetam page
	Cognition No effect		NoneNo effect	1 study	24 people
Studies that measured cognition Neuropsychological changes in demented patients treated with acetyl-L-carnitineInt J Clin Pharmacol Res · PMID 2387665
	Memory	Improves (the measure goes up)		1 study	16 people
Studies that measured memory Increase in the power of human memory in normal man through the use of drugsPsychopharmacology · PMID 826948

Panax Ginseng (Korean Ginseng)

Alzheimer's Disease Symptoms: improves
Attention: improves
Cognition: improves

Panax Ginseng (Korean Ginseng): outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People
	Alzheimer's Disease Symptoms Small Improvement	Improves (the measure goes down)	Small effect	1 study	158 people
Studies that measured alzheimer's disease symptoms Heat-processed ginseng enhances the cognitive function in patients with moderately severe Alzheimer's diseaseNutr Neurosci · PMID 22780999
	Attention Small Improvement	Improves (the measure goes up)	Small effect	1 study	82 people
Studies that measured attention Efficacy of Panax ginseng Meyer Herbal Preparation HRG80 in Preventing and Mitigating Stress-Induced Failure of Cognitive Functions in Healthy Subjects: A Pilot, Randomized, Double-Blind, Placebo-Controlled Crossover TrialPharmaceuticals · PMID 32235339
	Cognition	Improves (the measure goes up)		9 studies	422 people
Studies that measured cognition Effects of Panax ginseng, consumed with and without glucose, on blood glucose levels and cognitive performance during sustained 'mentally demanding' tasksJ Psychopharmacol · PMID 16401645 Improvement of cognitive deficit in Alzheimer's disease patients by long term treatment with korean red ginsengJ Ginseng Res · PMID 23717092 Effects of Korean Red Ginseng on Cognitive and Motor Function: A Double-blind, Randomized, Placebo-controlled TrialJ Ginseng Res · PMID 23717119 and 6 more on the Panax Ginseng (Korean Ginseng) page
	Blood glucose	Improves (the measure goes down)		3 studies	60 people
Studies that measured blood glucose Korean red ginseng (Panax ginseng C.A. Meyer) root fractions: differential effects on postprandial glycemia in healthy individualsJ Ethnopharmacol · PMID 21619921 Effect of Korean red ginseng on arterial stiffness in subjects with hypertensionJ Altern Complement Med · PMID 21235416 Effects of acute supplementation of Panax ginseng on endurance running in a hot & humid environmentIndian J Med Res · PMID 21321426
	Subjective Well-Being	Improves (the measure goes up)		2 studies	30 people
Studies that measured subjective well-being Ginseng does not enhance psychological well-being in healthy, young adults: results of a double-blind, placebo-controlled, randomized clinical trialJ Am Diet Assoc · PMID 11424544 Effects of Panax ginseng on quality of lifeAnn Pharmacother · PMID 11895046
	Cognitive Decline	Improves (the measure goes down)		1 study	61 people
	Processing Speed	Improves (the measure goes up)		1 study	32 people
	Reaction Time	Improves (the measure goes up)		1 study	222 people
	Blood Pressure	Improves (the measure goes down)			48 people
	Motor Control	Improves (the measure goes up)			112 people
	Stress Signs and Symptoms	Improves (the measure goes down)			50 people
	Working Memory	Improves (the measure goes up)			28 people

Iron

"Measures of Intelligence ": improves
Attention: improves
Memory: improves

Iron: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People
	"Measures of Intelligence " Small Improvement	Improves (the measure goes up)	Small effect		3,105 people
	Attention	Improves (the measure goes up)		2 studies	339 people
Studies that measured attention Effects of iron supplementation on cognitive development in school-age children: Systematic review and meta-analysis.PLoS One · PMID 37368919 Effect of Oral Iron Supplementation on Cognitive Function among Children and Adolescents in Low- and Middle-Income Countries: A Systematic Review and Meta-Analysis.Nutrients · PMID 36558491
	Memory	Improves (the measure goes up)			718 people

Fish Oil

ADHD Symptoms: improves
Depression Symptoms: improves
Aggression: improves

Fish Oil: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People
	ADHD Symptoms Small Improvement	Improves (the measure goes down)	Small effect	7 studies	198 people
Studies that measured adhd symptoms A randomized double-blind, placebo-controlled study of the effects of supplementation with highly unsaturated fatty acids on ADHD-related symptoms in children with specific learning difficultiesProg Neuropsychopharmacol Biol Psychiatry · PMID 11817499 Reduced Symptoms of Inattention after Dietary Omega-3 Fatty Acid Supplementation in Boys with and without Attention Deficit/Hyperactivity DisorderNeuropsychopharmacology · PMID 25790022 A randomized, double-blind, placebo-controlled trial of docosahexaenoic acid supplementation in children with attention-deficit/hyperactivity disorderJ Pediatr · PMID 11487742 and 4 more on the Fish Oil page
	Depression Symptoms	Improves (the measure goes down)		14 studies	122 people
Studies that measured depression symptoms The effect of omega 3 fatty acid supplementation on premenstrual syndrome and health-related quality of life: a randomized clinical trialJ Psychosom Obstet Gynaecol · PMID 28707491 Effect of maternal docosahexaenoic acid supplementation on postpartum depression and information processingAm J Obstet Gynecol · PMID 12748510 Omega-3 fatty acids for a better mental state in working populations - Happy Nurse Project: A 52-week randomized controlled trialJ Psychiatr Res · PMID 29627596 and 11 more on the Fish Oil page
	Aggression	Improves (the measure goes up)		2 studies	33 people
Studies that measured aggression Cognitive and physiological effects of Omega-3 polyunsaturated fatty acid supplementation in healthy subjectsEur J Clin Invest · PMID 16269019 Omega-3 Supplementation and the Neural Correlates of Negative Affect and Impulsivity: A Double-Blind, Randomized, Placebo-Controlled Trial in Midlife AdultsPsychosom Med · PMID 28121722
	Attention	Improves (the measure goes up)		2 studies	252 people
Studies that measured attention High-dose eicosapentaenoic acid (EPA) improves attention and vigilance in children and adolescents with attention deficit hyperactivity disorder (ADHD) and low endogenous EPA levelsTransl Psychiatry · PMID 31745072 Effect of supplementation with long-chain ω-3 polyunsaturated fatty acids on behavior and cognition in children with attention deficit/hyperactivity disorder (ADHD): a randomized placebo-controlled intervention trialProstaglandins Leukot Essent Fatty Acids · PMID 24958525
	Cognitive Decline	Improves (the measure goes down)		2 studies	3,558 people
Studies that measured cognitive decline Effect of Omega-3 Fatty Acids, Lutein/Zeaxanthin, or Other Nutrient Supplementation on Cognitive Function: The AREDS2 Randomized Clinical TrialJAMA · PMID 26305649 Beneficial effects of docosahexaenoic acid on cognition in age-related cognitive declineAlzheimers Dement · PMID 20434961
	Postpartum Depression Symptoms	Improves (the measure goes down)		2 studies	89 people
	Anxiety Symptoms	Improves (the measure goes down)		1 study	33 people
	Cognition	Improves (the measure goes up)		1 study	1,525 people
	Memory	Improves (the measure goes up)		1 study	65 people
	Subjective Well-Being	Improves (the measure goes up)		1 study	87 people
	Cerebral Blood Flow	Improves (the measure goes up)			22 people
	Cerebral Oxygenation	Improves (the measure goes up)			22 people
	Fatigue Symptoms	Improves (the measure goes down)			33 people
	Processing Accuracy	Improves (the measure goes up)			33 people
	Reaction Time	Improves (the measure goes up)			33 people
	Working Memory	Improves (the measure goes up)			95 people

Saffron

Anxiety Symptoms: improves
Depression Symptoms: improves
Cognitive Decline: improves

Saffron: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People
	Anxiety Symptoms Small Improvement	Improves (the measure goes down)	Small effect	6 studies	76 people
Studies that measured anxiety symptoms Crocus sativus L. versus Citalopram in the Treatment of Major Depressive Disorder with Anxious Distress: A Double-Blind, Controlled Clinical TrialPharmacopsychiatry · PMID 27701683 The effects of alcoholic extract of saffron (Crocus satious L.) on mild to moderate comorbid depression-anxiety, sleep quality, and life satisfaction in type 2 diabetes mellitus: A double-blind, randomized and placebo-controlled clinical trialComplement Ther Med · PMID 30477839 A double-blind, randomized and placebo-controlled trial of Saffron (Crocus sativus L.) in the treatment of anxiety and depressionJ Complement Integr Med · PMID 27101556 and 3 more on the Saffron page
	Depression Symptoms	Improves (the measure goes down)		18 studies	111 people
Studies that measured depression symptoms Crocus Sativus L. (saffron) versus sertraline on symptoms of depression among older people with major depressive disorders-a double-blind, randomized intervention studyPsychiatry Res · PMID 31669837 Saffron improved depression and reduced homocysteine level in patients with major depression: A Randomized, double-blind studyAvicenna J Phytomed · PMID 29387573 Crocus sativus L. (petal) in the treatment of mild-to-moderate depression: a double-blind, randomized and placebo-controlled trialPhytomedicine · PMID 16979327 and 15 more on the Saffron page
	Cognitive Decline	Improves (the measure goes down)			35 people
	Memory	Improves (the measure goes up)			76 people

Nitrate

Blood Pressure: improves
Oxygen Cost of Exercise: improves
Cognitive Decline: improves

Nitrate: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People
	Blood Pressure Small Improvement	Improves (the measure goes down)	Small effect	6 studies	12 people
Studies that measured blood pressure Effect of inorganic nitrate supplementation on blood pressure in older adults: A systematic review and meta-analysisNitric Oxide · PMID 33905826 Effects of short-term dietary nitrate supplementation on blood pressure, O2 uptake kinetics, and muscle and cognitive function in older adultsAm J Physiol Regul Integr Comp Physiol · PMID 23174856 Nitrate Derived From Beetroot Juice Lowers Blood Pressure in Patients With Arterial Hypertension: A Systematic Review and Meta-Analysis.Front Nutr · PMID 35369064 and 3 more on the Nitrate page
	Oxygen Cost of Exercise	Improves (the measure goes up)		2 studies	12 people
Studies that measured oxygen cost of exercise Dietary nitrate supplementation reduces the O2 cost of walking and running: a placebo-controlled studyJ Appl Physiol · PMID 21071588 The effects of dietary nitrate supplementation on endurance exercise performance and cardiorespiratory measures in healthy adults: a systematic review and meta-analysis.J Int Soc Sports Nutr · PMID 34243756
	Cognitive Decline	Improves (the measure goes down)			12 people
	Functionality in Elderly or Injured	Improves (the measure goes up)			12 people

Melatonin

Insomnia Signs and Symptoms: improves
Sleep Quality: improves

Melatonin: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People
	Insomnia Signs and Symptoms Large Improvement	Improves (the measure goes down)	Large effect	5 studies	40 people
Studies that measured insomnia signs and symptoms The effect of prolonged-release melatonin on sleep measures and psychomotor performance in elderly patients with insomniaInt Clin Psychopharmacol · PMID 19584739 Evaluation of sleep, puberty and mental health in children with long-term melatonin treatment for chronic idiopathic childhood sleep onset insomniaPsychopharmacology · PMID 21340475 Prolonged-release melatonin improves sleep quality and morning alertness in insomnia patients aged 55 years and older and has no withdrawal effectsJ Sleep Res · PMID 18036082 and 2 more on the Melatonin page
	Sleep Quality	Improves (the measure goes up)			40 people

Pramiracetam

Memory: improves
Forgetting: improves

Pramiracetam: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People
	Memory Small Improvement	Improves (the measure goes up)	Small effect	2 studies	35 people
Studies that measured memory Placebo-controlled study of pramiracetam in young males with memory and cognitive problems resulting from head injury and anoxiaBrain Inj · PMID 1786500 Memory training and drug therapy act differently on memory and metamemory functioning: evidence from a pilot studyArch Gerontol Geriatr · PMID 18653001
	Forgetting Small Improvement	Improves (the measure goes up)	Small effect	1 study	24 people
Studies that measured forgetting Pramiracetam effects on scopolamine-induced amnesia in healthy volunteersArch Gerontol Geriatr · PMID 15374306

Theanine

Anxiety Symptoms: improves
Alertness
Reaction Time: improves

Theanine: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People
	Anxiety Symptoms Small Improvement	Improves (the measure goes down)	Small effect	2 studies	46 people
Studies that measured anxiety symptoms L-Theanine reduces psychological and physiological stress responsesBiol Psychol · PMID 16930802 The Effects of Green Tea Amino Acid L-Theanine Consumption on the Ability to Manage Stress and Anxiety Levels: a Systematic Review.Plant Foods Hum Nutr · PMID 31758301
	Alertness No effect		NoneNo effect		86 people
	Reaction Time	Improves (the measure goes up)		5 studies	144 people
Studies that measured reaction time Acute effects of theanine, caffeine and theanine-caffeine combination on attentionNutr Neurosci · PMID 26869148 The effects of L-theanine, caffeine and their combination on cognition and moodBiol Psychol · PMID 18006208 l-Theanine and caffeine improve target-specific attention to visual stimuli by decreasing mind wandering: a human functional magnetic resonance imaging studyNutr Res · PMID 29420994 and 2 more on the Theanine page
	Attention	Improves (the measure goes up)		4 studies	216 people
Studies that measured attention L-theanine and caffeine in combination affect human cognition as evidenced by oscillatory alpha-band activity and attention task performanceJ Nutr · PMID 18641209 A double-blind, placebo-controlled study evaluating the effects of caffeine and L-theanine both alone and in combination on cerebral blood flow, cognition and moodPsychopharmacology · PMID 25761837 L-theanine improves neurophysiological measures of attention in a dose-dependent manner: a double-blind, placebo-controlled, crossover study.Nutr Neurosci · PMID 32777998 and 1 more on the Theanine page
	Executive Function	Improves (the measure goes up)		3 studies	120 people
Studies that measured executive function Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled TrialNutrients · PMID 31623400 Caffeine and theanine exert opposite effects on attention under emotional arousalCan J Physiol Pharmacol · PMID 28044450 Effects of l-Theanine on Cognitive Function in Middle-Aged and Older Subjects: A Randomized Placebo-Controlled StudyJ Med Food · PMID 33751906
	Sleep Quality	Improves (the measure goes up)		2 studies	30 people
	Subjective Well-Being	Improves (the measure goes up)		2 studies	62 people
	Cortisol	Improves (the measure goes down)		1 study	38 people
	Prepulse Inhibition	Improves (the measure goes up)		1 study	14 people
	Blood Pressure	Improves (the measure goes down)			72 people
	Depression Symptoms	Improves (the measure goes down)			30 people
	Fatigue Symptoms	Improves (the measure goes down)			24 people
	Headaches	Improves (the measure goes down)			24 people
	Motor Speed	Improves (the measure goes up)			30 people
	Numerical Memory	Improves (the measure goes up)			24 people
	Processing Accuracy	Improves (the measure goes up)			53 people
	Processing Speed	Improves (the measure goes up)			24 people
	Sedation	Improves (the measure goes up)			16 people
	Sleep Disturbance Signs and Symptoms	Improves (the measure goes down)			30 people
	Sleep Latency	Improves (the measure goes down)			30 people
	Verbal Fluency	Improves (the measure goes up)			30 people
	Verbal Memory	Improves (the measure goes up)			30 people
	Working Memory	Improves (the measure goes up)			106 people

Zinc

Cognition: improves
Depression Symptoms: improves
Serum BDNF: improves

Zinc: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People
	Cognition Small Improvement	Improves (the measure goes up)	Small effect	1 study	180 people
Studies that measured cognition Normalization of zinc intake enhances neurological retrieval of patients suffering from ischemic strokesNutr Neurosci · PMID 19761652
	Depression Symptoms	Improves (the measure goes down)		3 studies	44 people
Studies that measured depression symptoms Zinc supplementation combined with antidepressant drugs for treatment of patients with depression: a systematic review and meta-analysisNutr Rev · PMID 32885249 Effect of zinc supplementation on mood states in young women: a pilot studyEur J Clin Nutr · PMID 20087376 Zinc supplementation augments efficacy of imipramine in treatment resistant patients: a double blind, placebo-controlled studyJ Affect Disord · PMID 19278731
	Serum BDNF	Improves (the measure goes up)		2 studies	44 people
Studies that measured serum bdnf Effects of zinc supplementation on efficacy of antidepressant therapy, inflammatory cytokines, and brain-derived neurotrophic factor in patients with major depressionNutr Neurosci · PMID 23602205 Zinc monotherapy increases serum brain-derived neurotrophic factor (BDNF) levels and decreases depressive symptoms in overweight or obese subjects: A double-blind, randomized, placebo-controlled trialNutr Neurosci · PMID 24621065
	Reaction Time	Improves (the measure goes up)		1 study	180 people
Studies that measured reaction time Zinc supplementation improved cognitive performance and taste acuity in Indian adolescent girlsJ Am Coll Nutr · PMID 20368377
	Interleukin 6	Improves (the measure goes down)			44 people
	TNF-Alpha	Improves (the measure goes down)			44 people

Wild Yam

Cognition: improves
Cognitive Decline: improves

Wild Yam: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People
	Cognition Small Improvement	Improves (the measure goes up)	Small effect	1 study	28 people
Studies that measured cognition Diosgenin-Rich Yam Extract Enhances Cognitive Function: A Placebo-Controlled, Randomized, Double-Blind, Crossover Study of Healthy Adults.Nutrients · PMID 29064406
	Cognitive Decline	Improves (the measure goes down)			28 people

Chlorogenic Acid

Subjective Well-Being: improves
Cognition

Chlorogenic Acid: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Subjective Well-Being Small Improvement	Improves (the measure goes up)	Small effect	1 study	39 people
	Cognition No effect		NoneNo effect	1 study	243 people

Nicotine

Anxiety Symptoms
Reaction Time: improves

Nicotine: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Anxiety Symptoms Mixed effect			1 study	31 people
	Reaction Time Small Improvement	Improves (the measure goes up)	Small effect	1 study	28 people

L-Carnitine

Body Fat: improves
Muscle Mass: improves
Memory: improves

L-Carnitine: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Body Fat Small Decrease	Improves (the measure goes down)	Small effect	1 study	66 people
Muscle Mass	Improves (the measure goes up)		3 studies	66 people
Memory	Improves (the measure goes up)		2 studies	455 people
Subjective Well-Being	Improves (the measure goes up)		2 studies	400 people
Fatigue Symptoms	Improves (the measure goes down)			66 people
Reaction Time	Improves (the measure goes up)			400 people
Verbal Memory	Improves (the measure goes up)			55 people

Phosphatidylserine

Cognition: improves
Cortisol: improves
Fatigue Symptoms: improves

Phosphatidylserine: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Cognition Small Improvement	Improves (the measure goes up)	Small effect	1 study	18 people
Cortisol	Improves (the measure goes down)		1 study	18 people
Fatigue Symptoms	Improves (the measure goes down)		1 study	18 people
Stress Signs and Symptoms	Improves (the measure goes down)		1 study	16 people
Processing Accuracy	Improves (the measure goes up)			18 people
Processing Speed	Improves (the measure goes up)			18 people
Subjective Well-Being	Improves (the measure goes up)			18 people
Testosterone	Improves (the measure goes up)			18 people

Ginger (Zingiber officinale)

Memory: improves
Reaction Time: improves

Ginger (Zingiber officinale): outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Memory Small Improvement	Improves (the measure goes up)	Small effect	1 study	60 people
	Reaction Time	Improves (the measure goes up)			60 people

D-Serine

Anxiety Symptoms: improves
Reaction Time: improves
Attention: improves

D-Serine: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Anxiety Symptoms Small Improvement	Improves (the measure goes down)	Small effect		35 people
Reaction Time	Improves (the measure goes up)		1 study	35 people
Attention	Improves (the measure goes up)			35 people
Serum BDNF	Improves (the measure goes up)			35 people
Subjective Well-Being	Improves (the measure goes up)			35 people
Verbal Fluency	Improves (the measure goes up)			35 people
Working Memory	Improves (the measure goes up)			35 people

Kanna

Cognition: improves
Executive Function: improves
Sleep Quality: improves

Kanna: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Cognition Small Improvement	Improves (the measure goes up)	Small effect		16 people
Executive Function Small Improvement	Improves (the measure goes up)	Small effect		16 people
Sleep Quality	Improves (the measure goes up)		1 study	16 people
Stress Signs and Symptoms	Improves (the measure goes down)		1 study	15 people
Memory	Improves (the measure goes up)			16 people
Reaction Time	Improves (the measure goes up)			31 people
Subjective Well-Being	Improves (the measure goes up)			16 people

PRL-8-53

Memory: improves
Motor Control
Working Memory: improves

PRL-8-53: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Memory Moderate Improvement	Improves (the measure goes up)	Moderate effect		47 people
Motor Control No effect		NoneNo effect		47 people
Working Memory	Improves (the measure goes up)		1 study	47 people
Reaction Time	Improves (the measure goes up)			47 people

Black seed

Attention: improves
Blood Pressure: changes; see studies
Bilirubin: changes; see studies

Black seed: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Attention Small Improvement	Improves (the measure goes up)	Small effect		40 people
Blood Pressure	Changes; see studies		1 study	40 people
Bilirubin	Changes; see studies			40 people
Cognition	Improves (the measure goes up)			40 people
Kidney Function	Improves (the measure goes up)			40 people
Memory	Improves (the measure goes up)			40 people
Processing Accuracy	Improves (the measure goes up)			40 people
Processing Speed	Improves (the measure goes up)			40 people
Working Memory	Improves (the measure goes up)			40 people

Kava

Cognition: improves
Subjective Well-Being: improves
Reaction Time: improves

Kava: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Cognition Small Improvement	Improves (the measure goes up)	Small effect		20 people
Subjective Well-Being	Improves (the measure goes up)		3 studies	20 people
Reaction Time	Improves (the measure goes up)		1 study	20 people

Green Tea Extract

Cerebral Blood Flow: worsens
Cognition: improves

Green Tea Extract: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Cerebral Blood Flow Small Decrease	Worsens (the measure goes down)	Small effect		27 people
	Cognition	Improves (the measure goes up)		2 studies	27 people

Ashwagandha

Alertness: improves
Reaction Time: improves
Working Memory: improves

Ashwagandha: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Alertness Small Improvement	Improves (the measure goes up)	Small effect		20 people
Reaction Time	Improves (the measure goes up)		1 study	20 people
Working Memory	Improves (the measure goes up)		1 study	50 people
Attention	Improves (the measure goes up)			50 people
Cognition	Improves (the measure goes up)			20 people
Executive Function	Improves (the measure goes up)			70 people
Memory	Improves (the measure goes up)			50 people
Motor Control	Improves (the measure goes up)			20 people
Processing Accuracy	Improves (the measure goes up)			20 people
Processing Speed	Improves (the measure goes up)			20 people
Spatial Processing	Improves (the measure goes up)			50 people

Bacopa Monnieri

Anxiety Symptoms: improves
Alzheimer's Disease Symptoms
Memory: improves

Bacopa Monnieri: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Anxiety Symptoms Small Improvement	Improves (the measure goes down)	Small effect		236 people
Alzheimer's Disease Symptoms No effect		NoneNo effect	1 study	34 people
Memory	Improves (the measure goes up)		12 studies	516 people
Stress Signs and Symptoms	Changes; see studies		1 study	24 people
Arterial Stiffness	Changes; see studies			24 people
Attention	Improves (the measure goes up)			370 people
Blood Pressure	Changes; see studies			72 people
Depression Symptoms	Changes; see studies			124 people
Fatigue Symptoms	Changes; see studies			24 people
Intermediate-Term Memory	Improves (the measure goes up)			36 people
Motor Speed	Improves (the measure goes up)			96 people
Numerical Memory	Improves (the measure goes up)			36 people
Reaction Time	Improves (the measure goes up)			156 people
Serum BDNF	Improves (the measure goes up)			36 people
Short-Term Memory (Simple)	Improves (the measure goes up)			36 people
Verbal Memory	Improves (the measure goes up)			36 people
Working Memory	Improves (the measure goes up)			242 people

Resveratrol

Cerebral Blood Flow: improves
Cognition: improves
Fatigue Symptoms: improves

Resveratrol: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	People
Cerebral Blood Flow Small Increase	Improves (the measure goes up)	Small effect	9 people
Cognition	Improves (the measure goes up)		9 people
Fatigue Symptoms	Improves (the measure goes down)		9 people

Vinpocetine

Memory: improves
Processing Accuracy: improves
Reaction Time: improves

Vinpocetine: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Memory Small improvement in memory tasks (healthy volunteers, small study)	Improves (the measure goes up)	Small effect		12 people
Processing Accuracy	Improves (the measure goes up)		1 study	12 people
Reaction Time	Improves (the measure goes up)			12 people

Ginkgo Biloba

Alzheimer's Disease Symptoms: improves
Attention
Cognitive Decline: improves

Ginkgo Biloba: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Alzheimer's Disease Symptoms Small Improvement	Improves (the measure goes down)	Small effect		404 people
Attention No effect		NoneNo effect	1 study	53 people
Cognitive Decline	Improves (the measure goes down)		9 studies	500 people
Cognition	Improves (the measure goes up)		3 studies	466 people
Memory	Improves (the measure goes up)		3 studies	335 people
Blood Flow	Improves (the measure goes up)		2 studies	48 people
Cerebral Blood Flow	Improves (the measure goes up)		1 study	57 people
Processing Speed	Improves (the measure goes up)		1 study	60 people
Reaction Time	Improves (the measure goes up)		1 study	20 people
Numerical Memory	Improves (the measure goes up)			20 people
Processing Accuracy	Improves (the measure goes up)			73 people
Verbal Fluency	Improves (the measure goes up)			96 people
Working Memory	Improves (the measure goes up)			13 people

Pycnogenol

Attention: improves
Cognition: improves
Subjective Well-Being: improves

Pycnogenol: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Attention Small Improvement	Improves (the measure goes up)	Small effect		53 people
Cognition	Improves (the measure goes up)		1 study	53 people
Subjective Well-Being	Improves (the measure goes up)			53 people

Rhodiola Rosea

Alertness: improves
Cognition: improves
Cortisol: improves

Rhodiola Rosea: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Alertness Small Improvement	Improves (the measure goes up)	Small effect		26 people
Cognition	Improves (the measure goes up)		3 studies	220 people
Cortisol	Improves (the measure goes down)		3 studies	26 people
Anti-Oxidant Enzyme Profile	Improves (the measure goes up)			26 people
Creatine Kinase	Changes; see studies			26 people
Fatigue Symptoms	Improves (the measure goes down)			220 people
Growth Hormone	Improves (the measure goes up)			26 people
Oxidative Stress Biomarkers	Improves (the measure goes down)			26 people
Processing Accuracy	Improves (the measure goes up)			121 people
Reaction Time	Improves (the measure goes up)			26 people
Subjective Well-Being	Improves (the measure goes up)			161 people
Testosterone	Improves (the measure goes up)			26 people

Peppermint

Attention: improves
Stress Signs and Symptoms: improves
Memory: improves

Peppermint: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Attention Small Improvement	Improves (the measure goes up)	Small effect		144 people
Stress Signs and Symptoms	Improves (the measure goes down)		1 study	144 people
Memory	Improves (the measure goes up)			144 people
Processing Accuracy	Improves (the measure goes up)			144 people
Processing Speed	Improves (the measure goes up)			144 people
Subjective Well-Being	Improves (the measure goes up)			144 people
Working Memory	Improves (the measure goes up)			144 people

Gotu Kola

Alertness: improves
Processing Accuracy: improves
Reaction Time: improves

Gotu Kola: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Alertness Small Improvement	Improves (the measure goes up)	Small effect		28 people
Processing Accuracy	Improves (the measure goes up)		1 study	28 people
Reaction Time	Improves (the measure goes up)			56 people
Subjective Well-Being	Improves (the measure goes up)			28 people

Docosahexaenoic Acid

Cerebral Blood Flow: improves
Cerebral Oxygenation: improves

Docosahexaenoic Acid: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Cerebral Blood Flow Small Increase	Improves (the measure goes up)	Small effect		22 people
	Cerebral Oxygenation	Improves (the measure goes up)		1 study	22 people

Cocoa Extract

Attention
Blood Pressure: improves
C-Reactive Protein (CRP): improves

Cocoa Extract: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Attention No effect		NoneNo effect	2 studies	178 people
Blood Pressure	Improves (the measure goes down)		10 studies	90 people
C-Reactive Protein (CRP)	Improves (the measure goes down)		1 study	90 people
Cerebral Blood Flow	Improves (the measure goes up)			16 people
Cerebral Oxygenation	Improves (the measure goes up)			16 people
Cognition	Improves (the measure goes up)			90 people
Fatigue Symptoms	Improves (the measure goes down)			16 people
Memory	Improves (the measure goes up)			162 people
Stress Signs and Symptoms	Improves (the measure goes down)			72 people
Subjective Well-Being	Improves (the measure goes up)			162 people
Working Memory	Improves (the measure goes up)			162 people

Choline

Cognition
Memory: improves
Reaction Time: improves

Choline: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Cognition No effect		NoneNo effect	1 study	13 people
Memory	Improves (the measure goes up)			13 people
Reaction Time	Improves (the measure goes up)			13 people
Working Memory	Improves (the measure goes up)			13 people

L-Tyrosine

Alertness
Adrenocorticotropic Hormone
Working Memory: improves

L-Tyrosine: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Alertness No effect		NoneNo effect	1 study	23 people
Adrenocorticotropic Hormone No effect		NoneNo effect		20 people
Working Memory	Improves (the measure goes up)		6 studies	140 people
Depression Symptoms	Improves (the measure goes down)		1 study	21 people
Reaction Time	Improves (the measure goes up)		1 study	35 people
Attention	Improves (the measure goes up)			57 people
Blood Pressure	Improves (the measure goes down)			65 people
Cortisol	Improves (the measure goes down)			40 people
Fatigue Symptoms	Improves (the measure goes down)			21 people
Motor Control	Improves (the measure goes up)			18 people
Muscular Endurance	Improves (the measure goes up)			15 people
Noradrenaline	Improves (the measure goes up)			8 people
Processing Accuracy	Improves (the measure goes up)			20 people
Processing Speed	Improves (the measure goes up)			20 people
Sleep Deprivation Symptoms	Improves (the measure goes down)			18 people
Strength	Improves (the measure goes up)			15 people
Stress Signs and Symptoms	Improves (the measure goes down)			21 people
Subjective Well-Being	Improves (the measure goes up)			21 people
Vigor/Activity	Improves (the measure goes up)			8 people

Anthocyanins

Working Memory
Verbal Memory

Anthocyanins: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Working Memory No effect on working memory (isolated supplement)		NoneNo effect	1 study	14 people
	Verbal Memory No effect on verbal memory (isolated supplement)		NoneNo effect		14 people

Cannabis

Attention
Driving Speed: improves
Driving Control: improves

Cannabis: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Attention No effect		NoneNo effect	1 study	120 people
Driving Speed	Improves (the measure goes up)		4 studies	110 people
Driving Control	Improves (the measure goes up)		3 studies	183 people
Balance	Improves (the measure goes up)		2 studies	80 people
Mood	Improves (the measure goes up)		2 studies	91 people
Cortisol	Improves (the measure goes down)		1 study	40 people
Motor Control	Improves (the measure goes up)		1 study	120 people
Motor Speed	Improves (the measure goes up)		1 study	40 people
Cognition	Improves (the measure goes up)			108 people
Driving Caution	Improves (the measure goes up)			87 people
Fatigue Symptoms	Improves (the measure goes down)			108 people
Hand-Eye Coordination	Improves (the measure goes up)			80 people
Reaction Time	Improves (the measure goes up)			80 people
Verbal Memory	Improves (the measure goes up)			91 people
Working Memory	Improves (the measure goes up)			29 people

Vitamin E

Cognitive Decline
Memory: improves
Verbal Fluency: improves

Vitamin E: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Cognitive Decline No effect		NoneNo effect	1 study	6,377 people
Memory	Improves (the measure goes up)			6,377 people
Verbal Fluency	Improves (the measure goes up)			6,377 people

Black Cohosh

Cognition
Memory: improves

Black Cohosh: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Cognition No effect		NoneNo effect	1 study	66 people
	Memory	Improves (the measure goes up)			66 people

Red Clover Extract

Attention
Blood Pressure: improves
Memory: improves

Red Clover Extract: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Attention No effect		NoneNo effect		28 people
Blood Pressure	Improves (the measure goes down)		1 study	28 people
Memory	Improves (the measure goes up)		1 study	28 people

DHEA

Cognition
Estrogen: changes; see studies
Testosterone: improves

DHEA: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Cognition No effect		NoneNo effect		225 people
Estrogen	Changes; see studies		8 studies	27 people
Testosterone	Improves (the measure goes up)		3 studies	27 people
Serum DHEA	Improves (the measure goes up)		2 studies	27 people
Cognitive Decline	Improves (the measure goes down)		1 study	27 people
Cortisol	Improves (the measure goes down)		1 study	20 people
Subjective Well-Being	Improves (the measure goes up)		1 study	225 people
Depression Symptoms	Improves (the measure goes down)			225 people

Creatine

Adrenaline
Cognition: improves
Subjective Well-Being: improves

Creatine: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Adrenaline No effect		NoneNo effect		19 people
Cognition	Improves (the measure goes up)		4 studies	280 people
Subjective Well-Being	Improves (the measure goes up)		3 studies	39 people
Alertness	Improves (the measure goes up)		2 studies	12 people
Attention	Improves (the measure goes up)		1 study	211 people
Memory	Improves (the measure goes up)		1 study	492 people
Cerebral Oxygenation	Improves (the measure goes up)			24 people
Cortisol	Improves (the measure goes down)			39 people
Dopamine	Improves (the measure goes up)			19 people
Executive Function	Improves (the measure goes up)			104 people
Fatigue Symptoms	Improves (the measure goes down)			43 people
Noradrenaline	Improves (the measure goes up)			19 people
Processing Speed	Improves (the measure goes up)			104 people
Sleep Deprivation Symptoms	Improves (the measure goes down)			39 people

Astaxanthin

Fat Oxidation
Motor Control: improves
Processing Accuracy: improves

Astaxanthin: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Fat Oxidation No effect		NoneNo effect		65 people
Motor Control	Improves (the measure goes up)		1 study	184 people
Processing Accuracy	Improves (the measure goes up)			772 people
Reaction Time	Improves (the measure goes up)			534 people

Caffeine

Memory: improves
Reaction Time: improves
Blood Pressure: changes; see studies

Caffeine: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Memory	Improves (the measure goes up)		5 studies	20 people
Reaction Time	Improves (the measure goes up)		5 studies	988 people
Blood Pressure	Changes; see studies		2 studies	102 people
Anxiety Symptoms Small Detriment	Worsens (the measure goes up)	Small effect	1 study	400 people
Cognition	Improves (the measure goes up)		1 study	40 people
Subjective Well-Being	Improves (the measure goes up)		1 study	102 people
Visual acuity (VA)	Improves (the measure goes up)		1 study	13 people
Wakefulness	Changes; see studies		1 study	102 people
Attention	Improves (the measure goes up)			211 people
Executive Function	Improves (the measure goes up)			988 people
Fatigue Symptoms	Changes; see studies			13 people
Processing Accuracy	Improves (the measure goes up)			988 people
Processing Speed	Improves (the measure goes up)			988 people
Testosterone	Improves (the measure goes up)			13 people
Verbal Learning	Improves (the measure goes up)			224 people

Lemon Balm

Anxiety Symptoms: improves
Memory: improves
Alertness: worsens

Lemon Balm: outcomes studied for Cognitive Improvement
Outcome	Effect	Size	Studies	People
Anxiety Symptoms	Improves (the measure goes down)		2 studies	16 people
Memory	Improves (the measure goes up)		2 studies	50 people
Alertness Moderate Detriment	Worsens (the measure goes down)	Moderate effect		15 people
Attention	Improves (the measure goes up)			20 people
Processing Speed	Improves (the measure goes up)			20 people
Subjective Well-Being	Improves (the measure goes up)			15 people
Working Memory	Improves (the measure goes up)			35 people

Curcumin

Cognition: improves

Curcumin: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Cognition	Improves (the measure goes up)		2 studies	501 people

Probiotics

Serum BDNF: improves

Probiotics: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Serum BDNF	Improves (the measure goes up)		1 study	2,372 people

Oxiracetam

Alzheimer's Disease Symptoms: improves

Oxiracetam: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Alzheimer's Disease Symptoms	Improves (the measure goes down)		1 study	24 people

Policosanol

Reaction Time: improves

Policosanol: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Reaction Time	Improves (the measure goes up)		1 study	30 people

Inositol

Forgetting: improves

Inositol: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Forgetting	Improves (the measure goes up)		1 study	12 people

Beta-Alanine

Serum BDNF: improves

Beta-Alanine: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Serum BDNF	Improves (the measure goes up)		1 study	14 people

CDP-Choline

Memory: improves

CDP-Choline: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Memory	Improves (the measure goes up)		1 study	95 people

Yohimbine

Blood Pressure: worsens
Cerebral Blood Flow: improves

Yohimbine: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Blood Pressure Small Detriment	Worsens (the measure goes up)	Small effect	1 study	9 people
	Cerebral Blood Flow	Improves (the measure goes up)			9 people

Branched-Chain Amino Acids

Fatigue Symptoms: changes; see studies

Branched-Chain Amino Acids: outcomes studied for Cognitive Improvement
Grade	Outcome	Effect	Size	Studies	People	Studies list
	Fatigue Symptoms	Changes; see studies			224 people

What the published studies found

21 automated readings

Automated reading of the published studies (Decosa evidence engine), for outcomes Dr. Grey has not graded yet. It is not a Dr. Grey grade and does not change one. How it is read

Ashwagandha: memory
The best available review (2026, 20 studies, 1,249 people) found a moderate improvement in memory. All 8 studies read agree. The evidence is moderate.
8 studies counted of 11 read: 3 reviews and 5 trials (393 people in the trials).
1. Systematic review, 2026; 20 studies, 1,249 people: improves (the review the verdict rests on). Effects of Withania somnifera (L.) Dunal (Ashwagandha) on cognitive and physical function in adults: a systematic review and meta-analysisPubMed 42199854
2. Systematic review, 2026; 16 studies; individuals with bipolar disorder: improves. Withania somnifera (ashwagandha), insulin, and lurasidone each demonstrated cognitive benefits Improving Cognition in Bipolar Disorder: A Systematic Review of Current Pharmacological and Nutraceutical ApproachesPubMed 41843701
3. Systematic review, 2020; 5 studies; older adults with MCI, schizophrenia, schizoaffective, bipolar disorder: improves. improved performance on cognitive tasks, executive function, attention A systematic review of the clinical use of Withania somnifera (Ashwagandha) to ameliorate cognitive dysfunctionPubMed 31742775
4. Randomised trial, 2026; 120 people; adults with self-reported cognitive and energy problems: improves. Greater improvement (p < .05) from baseline scores Safety and Efficacy of Ashwagandha Root Extract on Cognition, Energy and Mood Problems in Adults: Prospective, Randomized, Placebo-Controlled StudyPubMed 39498904
5. Randomised trial, 2026; 85 people; children aged 6-12 with attention or memory concerns: improves. Improvements were also observed in delayed word recall A clinical assessment of the therapeutic effects of Ashwagandha root extract on cognitive performance, sleep, and fatigue in children aged 6-12 yearsPubMed 41889719
6. Crossover trial, 2022; 13 people; 13 healthy volunteers: improves. increased STT-determined working memory as demonstrated Effects of Acute Ashwagandha Ingestion on Cognitive FunctionPubMed 36231152
7. Randomised trial, 2021; 125 people; healthy stressed adults: improves. significantly improved recall memory, and the total error rate Efficacy and Safety of Ashwagandha Root Extract on Cognitive Functions in Healthy, Stressed Adults: A Randomized, Double-Blind, Placebo-Controlled StudyPubMed 34858513
8. Randomised trial, 2017; 50 people; adults with mild cognitive impairment: improves. significant improvements compared with the placebo group in both immediate and general memory Efficacy and Safety of Ashwagandha (Withania somnifera (L.) Dunal) Root Extract in Improving Memory and Cognitive FunctionsPubMed 28471731
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Caffeine: attention
A Cochrane review (2010, 13 studies) found a moderate improvement in attention. That review studied persons with jet lag or shift work disorder. 6 of the 7 studies read agree; 1 found no clear difference. The evidence is moderate.
7 studies counted of 10 read: 5 reviews and 2 trials (164 people in the trials).
1. Meta-analysis, 2010; 13 studies; persons with jet lag or shift work disorder: improves (the review the verdict rests on). Caffeine for the prevention of injuries and errors in shift workersPubMed 20464765
2. Meta-analysis, 2023; 4 studies, 76 people; children with ADHD: no clear difference. no significant difference when comparing placebo with caffeine Effects of Caffeine on Main Symptoms in Children with ADHD: A Systematic Review and Meta-Analysis of Randomized TrialsPubMed 37759905
3. Systematic review, 2022; animals with ADHD-like symptoms: improves. Caffeine treatment increases attention and improves learning Effects of Caffeine Consumption on Attention Deficit Hyperactivity Disorder (ADHD) Treatment: A Systematic Review of Animal StudiesPubMed 35215389
4. Meta-analysis, 2021; 13 studies: improves. significant impacts of caffeine only emerged on attention Caffeine and Cognitive Functions in Sports: A Systematic Review and Meta-AnalysisPubMed 33800853
5. Meta-analysis, 2020; 45 studies; sleep deprived/restricted individuals: improves. improved response time (44 EEs; g = 0.86 Effects of acute caffeine consumption following sleep loss on cognitive, physical, occupational and driving performance: A systematic review and meta-analysisPubMed 31837359
6. Randomised trial, 2024; 127 people: improves. showed a performance benefit as well as reported being more on task Examining the effects of caffeine during an auditory attention taskPubMed 39098270
7. Crossover trial, 2023; 37 people: improves. lower in the caffeine condition vs. the placebo condition Relationship between Habitual Caffeine Consumption, Attentional Performance, and Individual Alpha Frequency during Total Sleep DeprivationPubMed 36981883
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Caffeine: memory
A Cochrane review (2010, 13 studies) found a large improvement in memory. That review studied persons with jet lag or shift work disorder. 4 of the 7 studies read agree; 2 found a worse result, 1 found no clear difference. The evidence is moderate.
Possible harm: 2 studies read reported a worse result for memory with Caffeine. One abstract says: "Instead, we observed a general impairment in recognition performance, suggesting a reduced ability to distinguish previously encountered from novel but similar faces." Check the studies below, and ask a doctor or pharmacist if this applies to you.
Side effects: 1 of the 2 studies that reported on them found more with Caffeine (increased activeness, nervousness).
7 studies counted of 10 read: 4 reviews and 3 trials (144 people in the trials).
1. Meta-analysis, 2010; 13 studies; persons with jet lag or shift work disorder: improves (the review the verdict rests on). memory (SMD -1.08; 95% CI -2.07 to -0.09) Caffeine for the prevention of injuries and errors in shift workersPubMed 20464765
2. Systematic review, 2022; animals with ADHD-like symptoms: improves. improves learning, memory, and olfactory discrimination Effects of Caffeine Consumption on Attention Deficit Hyperactivity Disorder (ADHD) Treatment: A Systematic Review of Animal StudiesPubMed 35215389
3. Meta-analysis, 2021; 13 studies: improves. it may also improve simple reaction time, choice reaction time, memory, or fatigue Caffeine and Cognitive Functions in Sports: A Systematic Review and Meta-AnalysisPubMed 33800853
4. Meta-analysis, 2020; 45 studies; sleep deprived or restricted individuals: improves. typically indicated benefit of caffeine on memory Effects of acute caffeine consumption following sleep loss on cognitive, physical, occupational and driving performance: A systematic review and meta-analysisPubMed 31837359
5. Randomised trial, 2025; 97 people: worsens. caffeine consumption did not improve the consolidation of face recognition memory. Instead, we observed a … Caffeine reduces accuracy in face recognition memory consolidationPubMed 40670616
6. Crossover trial, 2024; 29 people; healthy physically active young adults: no clear difference. memory were not affected after either caffeine dose Effects of different doses of caffeine on cognitive performance in healthy physically active individualsPubMed 39231871
7. Randomised trial, 2024; 18 people; healthy habitual caffeine consumers: worsens. Acute caffeine administration impaired spatial working memory in habitual coffee/tea drinkers: A randomized, placebo-controlled, double-blind studyPubMed 39244155
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Creatine: memory
The best available review (2024, 16 studies, 492 people) found a small improvement in memory. That review studied adults aged 20.8-76.4 years, healthy and diseased. 5 of the 6 studies read agree; 1 found no clear difference. The evidence is moderate.
Side effects: 1 of the 3 studies that reported on them found more with Creatine.
6 studies counted of 9 read: 3 reviews and 2 trials (150 people in the trials).
1. Systematic review, 2024; 16 studies, 492 people; adults aged 20.8-76.4 years, healthy and diseased: improves (the review the verdict rests on). significant positive effects on memory (SMD = 0.31 The effects of creatine supplementation on cognitive function in adults: a systematic review and meta-analysisPubMed 39070254
2. Meta-analysis, 2023; 8 studies; healthy individuals: improves. creatine supplementation improved measures of memory Effects of creatine supplementation on memory in healthy individuals: a systematic review and meta-analysis of randomized controlled trialsPubMed 35984306
3. Systematic review, 2018; 6 studies, 281 people; healthy individuals: improves. short term memory and intelligence/reasoning may be improved Effects of creatine supplementation on cognitive function of healthy individuals: A systematic review of randomized controlled trialsPubMed 29704637
4. Study, 2025; older adults: improves. modest improvements in memory, processing speed Creatine supplementation and exercise in aging: a narrative review of the muscle-brain axis and its impact on cognitive and physical healthPubMed 41601887
5. Randomised trial, 2011; 128 people; young adult females, vegetarians and omnivores: improves. creatine supplementation resulted in better memory The influence of creatine supplementation on the cognitive functioning of vegetarians and omnivoresPubMed 21118604
6. Randomised trial, 2008; 22 people; non-sleep deprived young adults: no clear difference. no significant group by time interactions for RT, CS, CSD, LRS, MP, RM, and MR Creatine supplementation does not improve cognitive function in young adultsPubMed 18579168
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Creatine: cognitive function
The studies disagree. The best available review (2024, 16 studies, 492 people) found little or no difference in cognitive function, while 6 of the 10 studies read found an improvement. The evidence is very weak.
10 studies counted of 11 read: 4 reviews and 6 trials (233 people in the trials).
1. Systematic review, 2024; 16 studies, 492 people; adults aged 20.8-76.4 years, healthy and diseased: no clear difference (the review the verdict rests on). no significant improvements were found on overall cognitive function The effects of creatine supplementation on cognitive function in adults: a systematic review and meta-analysisPubMed 39070254
2. Systematic review, 2025; 7 studies, 275 people; individuals with bipolar disorder: improves. Lifestyle-based interventions targeting neurocognition in bipolar disorders - a systematic review of randomized controlled trialsPubMed 40639301
3. Systematic review, 2024; vegans, vegetarians, elderly, sleep deprived, hypoxic individuals: unclear: evidence too weak to tell. demonstrated somewhat equivocal results for effects on cognition Creatine supplementation research fails to support the theoretical basis for an effect on cognition: Evidence from a systematic reviewPubMed 38582412
4. Meta-analysis, 2023; 8 studies; healthy individuals: improves. creatine supplementation improved measures of memory compared with placebo Effects of creatine supplementation on memory in healthy individuals: a systematic review and meta-analysis of randomized controlled trialsPubMed 35984306
5. Randomised trial, 2026; 40 people; young healthy active omnivorous males and females: no clear difference. no effects of Cr on any of the cognitive tasks Creatine monohydrate improved cycling Wingate performance but not cognitive function in young active males and femalesPubMed 41960895
6. Randomised trial, 2026; 36 people; perimenopausal and menopausal women: improves. superior to placebo in enhancing reaction time The Effects of 8-Week Creatine Hydrochloride and Creatine Ethyl Ester Supplementation on Cognition, Clinical Outcomes, and Brain Creatine Levels in Perimenopausal and Menopausal Women (CONCRET-MENOPA): A Randomized Controlled TrialPubMed 40854087
7. Crossover trial, 2025; 14 people; physically active men: improves. improved cognitive performance on the DCT Effects of Creatine Monohydrate Loading on Sleep Metrics, Physical Performance, Cognitive Function, and Recovery in Physically Active Men: A Randomized, Double-Blind, Placebo-Controlled, Crossover TrialPubMed 41470776
8. Crossover trial, 2015; 15 people; healthy young adults: improves. decrements in cognitive performance, specifically attentional capacity, were restored Creatine supplementation enhances corticomotor excitability and cognitive performance during oxygen deprivationPubMed 25632150
9. Randomised trial, 2011; 128 people; young adult females: mixed results. creatine supplementation resulted in better memory The influence of creatine supplementation on the cognitive functioning of vegetarians and omnivoresPubMed 21118604
10. Randomised trial, 2009: improves. improvement over the placebo condition on several measures Cognitive effects of creatine ethyl ester supplementationPubMed 19773644
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Curcumin: memory
The studies disagree. The best available review (2026) found an improvement in memory, while 1 of the 9 studies read found mixed results. The evidence is very weak.
Side effects: 3 of the 5 studies that reported on them found more with Curcumin (gastrointestinal side effects, gastrointestinal adverse events).
9 studies counted of 11 read: 6 reviews and 3 trials (180 people in the trials).
1. Systematic review, 2026; adults, particularly older adults: improves (the review the verdict rests on). curcumin supplementation could improve cognitive domains, including memory Curcumin and Cognitive Health: Insights from Randomized Controlled TrialsPubMed 42411087
2. Meta-analysis, 2025; 10 studies, 531 people: mixed results. significant improvements in working memory (SMD = 1.01 Targeting cognitive aging with curcumin supplementation: A systematic review and meta-analysisPubMed 40579315
3. Systematic review, 2025; 29 studies; rodent models of dementia: improves. Cognitive performance improved in around 80% of studies Curcumin and Dementia: A Systematic Review of Its Effects on Oxidative Stress and Cognitive Outcomes in Animal ModelsPubMed 40725274
4. Systematic review, 2024; 12 studies; adults 18 years and older: improves. studies found curcumin significantly improves working memory in the following adult groups: non-demented, metabolically impaired, … Curcumin and Cognitive Function: A Systematic Review of the Effects of Curcumin on Adults With and Without Neurocognitive DisordersPubMed 39318960
5. Meta-analysis, 2021; 8 studies, 389 people: improves. improvement in working memory (Hedges' g = 0.396 The Effect of Curcumin Differs on Individual Cognitive Domains across Different Patient Populations: A Systematic Review and Meta-AnalysisPubMed 34959636
6. Meta-analysis, 2019; 6 studies, 289 people; older adults and patients with Alzheimer's disease: improves. scores on measures of cognitive function (SMD = 0.33, 95% confidence interval [CI] [0.05, 0.62] Curcumin intervention for cognitive function in different types of people: A systematic review and meta-analysisPubMed 30575152
7. Randomised trial, 2020; 80 people; healthy older adults aged 50-80 years: improves. better working memory performance at 12-weeks Further Evidence of Benefits to Mood and Working Memory from Lipidated Curcumin in Healthy Older People: A 12-Week, Double-Blind, Placebo-Controlled, Partial Replication StudyPubMed 32512782
8. Randomised trial, 2018; 40 people; non-demented adults aged 51-84 years: improves. SRT Consistent Long-Term Retrieval improved with curcumin Memory and Brain Amyloid and Tau Effects of a Bioavailable Form of Curcumin in Non-Demented Adults: A Double-Blind, Placebo-Controlled 18-Month TrialPubMed 29246725
9. Randomised trial, 2015; 60 people; healthy adults aged 60-85: improves. curcumin significantly improved performance on sustained attention and working memory tasks Investigation of the effects of solid lipid curcumin on cognition and mood in a healthy older populationPubMed 25277322
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Fish Oil: memory
The best available review (2020, 29 studies, 4,247 people) found little or no difference in memory. 4 of the 7 studies read agree; 2 found an improvement, 1 found mixed results. The evidence is moderate.
7 studies counted of 8 read: 5 reviews and 2 trials (271 people in the trials).
1. Meta-analysis, 2020; 29 studies, 4,247 people: no clear difference (the review the verdict rests on). no main effect of omega-3 fatty acid supplementation Omega-3 and its domain-specific effects on cognitive test performance in youths: A meta-analysisPubMed 32070694
2. Meta-analysis, 2020; 10 studies, 2,327 people; elderly individuals with age-related cognitive decline: no clear difference. minimal or no pooled incremental effects on memory Docosahexaenoic acid supplementation in age-related cognitive decline: a systematic review and meta-analysisPubMed 32060571
3. Meta-analysis, 2020; 25 studies; non-demented adults, including mild cognitive impairment: improves. only memory function showed a mild benefit Long-chain omega-3 polyunsaturated fatty acids and cognitive decline in non-demented adults: a systematic review and meta-analysisPubMed 31841161
4. Systematic review, 2020; 10 studies; mild Cognitive Impairment, Subjective Cognitive Impairment, dementia: mixed results. presented significant benefits in certain domains of cognitive functions Dietary interventions and cognition: A systematic review of clinical trialsPubMed 33099465
5. Meta-analysis, 2015; 24 studies; healthy adults, children, ADHD, related disorders: improves. In those with low n-3 PUFA status, supplementation improved short-term memory. Omega-3 polyunsaturated fatty acid supplementation and cognition: A systematic review and meta-analysisPubMed 26040902
6. Randomised trial, 2023; healthy older adults with memory complaints: no clear difference. did not significantly affect memory function in healthy, non-demented, older individuals Effects of Long-Chain Polyunsaturated Fatty Acids in Combination with Lutein and Zeaxanthin on Episodic Memory in Healthy Older AdultsPubMed 37447152
7. Randomised trial, 2020; 271 people; mid-life adults with low LCn-3FA consumption: no clear difference. did not affect performance in any of the four cognitive domains The effects of omega-3 fatty acids on neuropsychological functioning and brain morphology in mid-life adults: a randomized clinical trialPubMed 31581959
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Folic Acid (Vitamin B9): memory
The studies read are too weak to tell whether Folic Acid (Vitamin B9) changes memory. The strongest review read studied people with mild cognitive impairment. The evidence is very weak.
11 studies counted of 11 read: 9 reviews and 2 trials (315 people in the trials).
1. Meta-analysis, 2018; 5 studies, 879 people; people with mild cognitive impairment: unclear: evidence too weak to tell (the review the verdict rests on). probably little or no effect of B vitamins Vitamin and mineral supplementation for preventing dementia or delaying cognitive decline in people with mild cognitive impairmentPubMed 30383288
2. Systematic review, 2026: improves. folic acid+DHA, and the DHA+EPA+vitamin E+tryptophan+melatonin were all effective in augmenting memory Nutritional supplements and cognition in healthy aging and mild cognitive impairment patients: a systematic review and network meta-analysisPubMed 41764841
3. Systematic review, 2022; 9 studies, 641 people: no clear difference. did not significantly change memory score compared to placebo Does folic acid supplementation have a positive effect on improving memory? A systematic review and meta-analysis of randomized controlled trialsPubMed 36518821
4. Systematic review, 2018; 38 studies; adults with normal cognition or MCI: no clear difference. improvements in performance on some objectively measured memory tests Over-the-Counter Supplement Interventions to Prevent Cognitive Decline, Mild Cognitive Impairment, and Clinical Alzheimer-Type Dementia: A Systematic ReviewPubMed 29255909
5. Systematic review, 2018; 16 studies: improves. improvements in performance, particularly in memory Effect of dietary interventions in mild cognitive impairment: a systematic reviewPubMed 30409231
6. Meta-analysis, 2014; 5 studies; individuals with mild cognitive impairment or Alzheimer's disease: improves. moderate beneficial effects of vitamins B supplementation on memory Efficacy of vitamins B supplementation on mild cognitive impairment and Alzheimer's disease: a systematic review and meta-analysisPubMed 25274113
7. Meta-analysis, 2010; 9 studies, 2,835 people: no clear difference. standardized mean differences were 0.01 (95% CI, -0.08 to 0.09) Effect of folic acid, with or without other B vitamins, on cognitive decline: meta-analysis of randomized trialsPubMed 20569758
8. Systematic review, 2008; 8 studies; healthy elderly and demented people: unclear: evidence too weak to tell. memory storage (WMD 0.14, 95% CI 0.04 to 0.24, P = 0.006) Folic acid with or without vitamin B12 for the prevention and treatment of healthy elderly and demented peoplePubMed 18843658
9. Systematic review, 2003; 4 studies; elderly healthy and demented people: no clear difference. found no benefit from folic acid with or without vitamin B12 in comparison with placebo Folic acid with or without vitamin B12 for cognition and dementiaPubMed 14584018
10. Randomised trial, 2016; 104 people; middle-aged and elderly patients with hyperhomocysteinemia: improves. significantly increased only for the vitamin B group B vitamin supplementation improves cognitive function in the middle aged and elderly with hyperhomocysteinemiaPubMed 24938711
11. Randomised trial, 2002; 211 people; healthy younger, middle-aged and older women: improves. significant positive effect on some measures of memory performance Short-term folate, vitamin B-12 or vitamin B-6 supplementation slightly affects memory performance but not mood in women of various agesPubMed 12042457
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Ginkgo Biloba: memory
A Cochrane review (2026, 82 studies, 10,613 people) found little or no difference in memory. That review studied people with cognitive impairment or dementia. 1 of the 5 studies read agree; 4 found an improvement. The evidence is moderate.
5 studies counted of 11 read: 3 reviews and 2 trials (193 people in the trials).
1. Meta-analysis, 2026; 82 studies, 10,613 people; people with cognitive impairment or dementia: no clear difference (the review the verdict rests on). ginkgo probably has little or no effect Ginkgo biloba for cognitive impairment and dementiaPubMed 41641880
2. Systematic review, 2023; 9 studies, 946 people; patients with mild neurocognitive disorder: improves. Significant effects were found in several domains of cognition (memory Ginkgo biloba Extract EGb 761 in the Treatment of Patients with Mild Neurocognitive Impairment: A Systematic ReviewPubMed 36994422
3. Meta-analysis, 2021; 23 studies, 2,019 people; patients with vascular cognitive impairment: improves. MDMMSE,EGb vs.blank = 3.04, 95% CI: 0.10-5.98 EGb in the Treatment for Patients with VCI: A Systematic Review and Meta-AnalysisPubMed 34504643
4. Randomised trial, 2022; 80 people; patients with psychiatric disorders undergoing ECT: improves. Gingko biloba increased MMSE and WMS-III scores Investigating the efficacy of Ginkgo biloba on the cognitive function of patients undergoing treatment with electric shock: a double-blind clinical trialPubMed 36762332
5. Randomised trial, 2014; 113 people; patients with mild cognitive impairment: improves. improvement of MQ increased in the treatment group [Ginkgo leaves tablet improved the memory quotient of patients with mild cognitive impairment: a clinical observation]PubMed 24758078
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Iron: memory
The best available review (2026, 17 studies) found an improvement in memory. That review studied children. 4 of the 7 studies read agree; 3 found no clear difference. The evidence is moderate.
Possible harm: 1 study read reported a worse result for memory with Iron. One abstract says: "increasing iron correlated poorer memory and general cognitive performance in adulthood" Check the studies below, and ask a doctor or pharmacist if this applies to you.
7 studies counted of 8 read: 5 reviews and 2 trials (94 people in the trials).
1. Systematic review, 2026; 17 studies; children: improves (the review the verdict rests on). modest benefits in domains such as intelligence, memory Effect of iron supplements on cognitive development in children: an umbrella reviewPubMed 41710280
2. Meta-analysis, 2025; 18 studies, 1,408 people; non-anemic children, adolescents, and menstruating adults: improves. In RCTs, supplementation improved symptoms of anxiety (d = 0.34), fatigue (d = 0.34), physical … Psychiatric and cognitive outcomes of iron supplementation in non-anemic children, adolescents, and menstruating adults: A meta-analysis and systematic reviewPubMed 40945632
3. Systematic review, 2022; 50 studies; adolescents: no clear difference. iron supplementation did not improve memory and recall Iron Status, Anemia, and Iron Interventions and Their Associations with Cognitive and Academic Performance in Adolescents: A Systematic ReviewPubMed 35011099
4. Systematic review, 2014; 11 studies; pre-menopausal women: improves. Increasing iron and zinc in pre-menopausal women and its effects on mood and cognition: a systematic reviewPubMed 25405366
5. Meta-analysis, 2010; 14 studies; children aged 6+, adolescents, and women: no clear difference. had no effect on non-anaemic participants, or on memory The effects of oral iron supplementation on cognition in older children and adults: a systematic review and meta-analysisPubMed 20100340
6. Randomised trial, 2025; 94 people; heart transplant recipients with iron deficiency: no clear difference. did not differ statistically significantly between study groups Cognitive Function Among Heart Transplant Recipients Before and After Intravenous Iron Supplement for Iron Deficiency: Results From a Randomized, Placebo-Controlled, Double-Blind Treatment TrialPubMed 41182019
7. Randomised trial, 1986; young pregnant women aged 14-24: improves. significant improvement on the most sensitive measure of short-term memory A randomized trial of oral iron on tests of short-term memory and attention span in young pregnant womenPubMed 3511017
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Lion's Mane: memory
The studies read do not show a clear benefit for memory. One reading found evidence too weak to tell, a second reading of the same search found mixed results. The evidence is very weak.
2 studies counted of 8 read: 1 trial.
1. Non-randomised trial, 2022; rTg4510 Tau mouse model: no clear difference. no improvements were seen in spatial memory Lion's Mane (Hericium erinaceus) Exerts Anxiolytic Effects in the rTg4510 Tau Mouse ModelPubMed 35877305
2. Randomised trial, 2018; wild-type mice: no clear difference. had no effect on spatial memory Dietary Supplementation of Lion's Mane Medicinal Mushroom, Hericium erinaceus (Agaricomycetes), and Spatial Memory in Wild-Type MicePubMed 29953363
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Lion's Mane: attention
The studies read are too weak to tell whether Lion's Mane changes attention. They lean toward an improvement, which is not enough to claim one. The evidence is very weak.
1 study counted of 7 read: 1 trial.
1. Crossover trial, 2023; healthy adults: improves. Acute Effects of Naturally Occurring Guayusa Tea and Nordic Lion's Mane Extracts on Cognitive PerformancePubMed 38140277
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Melatonin: memory
The studies read do not show a clear benefit for memory. One reading found mixed results, a second reading of the same search found little or no difference. The evidence is very weak.
Possible harm: 2 studies read reported a worse result for memory with Melatonin. One abstract says: "Memory scanning speed and perception of mental load were adversely affected." Check the studies below, and ask a doctor or pharmacist if this applies to you.
8 studies counted of 11 read: 3 reviews and 5 trials (129 people in the trials).
1. Systematic review, 2026: improves (the review the verdict rests on). Nutritional supplements and cognition in healthy aging and mild cognitive impairment patients: a systematic review and network meta-analysisPubMed 41764841
2. Systematic review, 2025; 26 studies, 23,839 people; patients with cognitive dysfunction induced by multiple sclerosis: worsens. Pharmacological treatment options for cognitive dysfunction induced by multiple sclerosis: a network meta-analysisPubMed 41127289
3. Meta-analysis, 2021; 22 studies: no clear difference. melatonin did not reduce memory function Neurocognitive effects of melatonin treatment in healthy adults and individuals with Alzheimer's disease and insomnia: A systematic review and meta-analysis of randomized controlled trialsPubMed 33957167
4. Randomised trial, 2020; 36 people; women undergoing adjuvant chemotherapy for breast cancer: improves. enhanced episodic memory (immediate and delayed) and recognition on RAVLT Clinical impact of melatonin on breast cancer patients undergoing chemotherapy; effects on cognition, sleep and depressive symptoms: A randomized, double-blind, placebo-controlled trialPubMed 32302347
5. Randomised trial, 2007; 13 people; non-sleep deprived volunteers: no clear difference. Cognitive performance following premature awakening from zolpidem or melatonin induced daytime sleepPubMed 17225476
6. Crossover trial, 2007; healthy adults undergoing fMRI memory tasks: improves. Exogenous melatonin further reduced activation in this region Melatonin and the human hippocampus, a time dependent interplayPubMed 17614839
7. Crossover trial, 2005; 80 people; 80 healthy adults: no clear difference. no memory or performance impairment (P > .05) Daytime sleep and performance following a zolpidem and melatonin cocktailPubMed 15700725
8. Randomised trial, 1993; police officers working seven successive night shifts: worsens. Memory scanning speed and perception of mental load were adversely affected Can melatonin improve shift workers' tolerance of the night shift? Some preliminary findingsPubMed 8261530
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
N-Acetylcysteine: memory
The studies disagree. The best available review (2022, 6 studies) did not settle it for memory, while 3 of the 6 studies read found an improvement. The evidence is very weak.
6 studies counted of 11 read: 3 reviews and 3 trials (117 people in the trials).
1. Meta-analysis, 2022; 6 studies; patients with schizophrenia: unclear: evidence too weak to tell (the review the verdict rests on). Antipsychotic Augmentation With N-Acetylcysteine for Patients With SchizophreniaPubMed 36170201
2. Meta-analysis, 2020; 7 studies, 440 people; patients with schizophrenia: improves. working memory improved with N-acetylcysteine supplementation Meta-analysis of randomised controlled trials with N-acetylcysteine in the treatment of schizophreniaPubMed 31826654
3. Meta-analysis, 2019; 25 studies, 1,951 people; patients with schizophrenia: improves. N-acetyl cysteine (NAC) had a significant effect on working memory ( P-value for interaction = … Effect of N-methyl-D-aspartate-receptor-enhancing agents on cognition in patients with schizophrenia: A systematic review and meta-analysis of double-blind randomised controlled trialsPubMed 30730250
4. Randomised trial, 2026; 59 people; patients with mild cognitive impairment: no clear difference. no significant differences between N-acetylcysteine and placebo Efficacy and safety of N-acetylcysteine in patients with mild cognitive impairment undergoing exercise-based cardiac rehabilitation program: a randomized controlled trialPubMed 42045982
5. Randomised trial, 2017; 58 people: improves. significantly higher working memory performance at week 24 Cognitive effects of adjunctive N-acetyl cysteine in psychosisPubMed 27894373
6. Randomised trial, 2012: no clear difference. failed to find changes in cognitive function Effects of N-acetyl cysteine on cognitive function in bipolar disorderPubMed 23066769
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Omega-3 Fatty Acids: memory
The best available review (2025, 58 studies) found a large improvement in memory. 4 of the 6 studies read agree; 1 found no clear answer, 1 found mixed results. The evidence is moderate.
6 studies counted of 8 read: 5 reviews and 1 trial (72 people in the trials).
1. Meta-analysis, 2025; 58 studies: improves (the review the verdict rests on). A systematic review and dose response meta analysis of Omega 3 supplementation on cognitive functionPubMed 40836005
2. Systematic review, 2022; 9 studies, 1,319 people: improves. Effects of Omega-3 Polyunsaturated Fatty Acids on Brain Functions: A Systematic ReviewPubMed 36381743
3. Meta-analysis, 2020; 29 studies, 4,247 people; youths: mixed results. beneficial effects of eicosapentaenoic acid (EPA)-rich Omega-3 and its domain-specific effects on cognitive test performance in youths: A meta-analysisPubMed 32070694
4. Meta-analysis, 2020; 25 studies; non-demented adults, including mild cognitive impairment: improves. only memory function showed a mild benefit Long-chain omega-3 polyunsaturated fatty acids and cognitive decline in non-demented adults: a systematic review and meta-analysisPubMed 31841161
5. Systematic review, 2018; 7 studies; patients with Alzheimer's disease: unclear: evidence too weak to tell. Most studies did not find statistically significant results Omega-3 fatty acids' supplementation in Alzheimer's disease: A systematic reviewPubMed 28466678
6. Randomised trial, 2024; 72 people; first-diagnosed, drug-naïve depression outpatients: improves. change of immediate memory at both week 4 and week 12 (p < 0.05) Omega-3 polyunsaturated fatty acids supplementation improves memory in first-diagnosed, drug-naïve patients with depression: Secondary analysis of data from a randomized controlled trialPubMed 38244783
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Panax Ginseng (Korean Ginseng): memory
The studies disagree. A Cochrane review (2010, 5 studies) did not settle it for memory, while 4 of the 6 studies read found an improvement. The evidence is very weak.
6 studies counted of 10 read: 3 reviews and 3 trials (206 people in the trials).
1. Meta-analysis, 2010; 5 studies: unclear: evidence too weak to tell (the review the verdict rests on). suggested improvement of some aspects of cognitive function Ginseng for cognitionPubMed 21154383
2. Meta-analysis, 2025; 8 studies; individuals with cognitive or memory impairment: improves. Cognitive Benefits of Ginseng: A Systematic Review and Meta-Analysis of Changes in Mini-Mental State Examination and Alzheimer's Disease Assessment Scale-Cognitive Subscale ScoresPubMed 40774237
3. Meta-analysis, 2024; 15 studies, 671 people; healthy people, cognitive impairment, schizophrenia, Alzheimer's: improves. significant effect on memory improvement (SMD = 0.19 Effects of Ginseng on Cognitive Function: A Systematic Review and Meta-AnalysisPubMed 39474788
4. Randomised trial, 2024; 80 people; adults aged 55 to 75 with subjective memory impairment: improves. Efficacy and Safety of Panax ginseng Sprout Extract in Subjective Memory Impairment: A Randomized, Double-Blind, Placebo-Controlled Clinical TrialPubMed 38931306
5. Randomised trial, 2022; 76 people: no clear difference. no inter-group difference in the primary Safety and efficacy of dietary supplement (gintonin-enriched fraction from ginseng) in subjective memory impairment: A randomized placebo-controlled trialPubMed 34504764
6. Crossover trial, 2020; 50 people: improves. observed in the attention d2 and memory tests Efficacy of Panax ginseng Meyer Herbal Preparation HRG80 in Preventing and Mitigating Stress-Induced Failure of Cognitive Functions in Healthy Subjects: A Pilot, Randomized, Double-Blind, Placebo-Controlled Crossover TrialPubMed 32235339
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Peppermint: memory
The 1 study read (144 people in all) mostly found an improvement in memory. The evidence is limited.
1 study counted of 3 read: 1 trial (144 people in the trials).
1. Randomised trial, 2008; 144 people; healthy volunteers: improves. Modulation of cognitive performance and mood by aromas of peppermint and ylang-ylangPubMed 18041606
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Phosphatidylserine: cognitive function
The best available review (2026, 11 studies) found little or no difference in cognitive function. That review studied children, adolescents, and adults with mental disorders. 3 of the 6 studies read agree; 3 found an improvement. The evidence is moderate.
6 studies counted of 9 read: 1 review and 5 trials (710 people in the trials).
1. Systematic review, 2026; 11 studies; children, adolescents, and adults with mental disorders: no clear difference (the review the verdict rests on). findings were heterogeneous and inconsistent across diagnostic groups The Impact of Citicoline/Phosphatidylserine Supplementation on Cognitive Performance and Executive Functions in Mental Disorders: A Systematic Review of Controlled TrialsPubMed 42538853
2. Crossover trial, 2013; recreationally trained individuals: no clear difference. does not affect CF or RT Phosphatidylserine and caffeine attenuate postexercise mood disturbance and perception of fatigue in humansPubMed 23746562
3. Crossover trial, 2011; 18 people; lower body resistance trained college aged males: improves. significantly reduced the time needed for a correct calculation The effects of IQPLUS Focus on cognitive function, mood and endocrine response before and following acute exercisePubMed 22017963
4. Randomised trial, 2010; 78 people: improves. memory scores in PS treated groups were significantly increased Soybean-derived phosphatidylserine improves memory function of the elderly Japanese subjects with memory complaintsPubMed 21103034
5. Randomised trial, 2001; 120 people: no clear difference. No significant differences were found in any of the outcome variables The influence of soy-derived phosphatidylserine on cognition in age-associated memory impairmentPubMed 11842880
6. Randomised trial, 1993; 494 people; elderly patients with moderate to severe cognitive decline: improves. Statistically significant improvements in the phosphatidylserine-treated group Cognitive decline in the elderly: a double-blind, placebo-controlled multicenter study on efficacy of phosphatidylserine administrationPubMed 8323999
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Probiotics: memory
The best available review (2026, 21 studies) found an improvement in memory. That review studied people across the human lifespan. 6 of the 8 studies read agree; 1 found no clear answer, 1 found no clear difference. The evidence is moderate.
8 studies counted of 9 read: 5 reviews and 3 trials (242 people in the trials).
1. Meta-analysis, 2026; 21 studies; people across the human lifespan: improves (the review the verdict rests on). Effects of probiotics on cognitive function across the human lifespan: a meta-analysisPubMed 40983638
2. Systematic review, 2025; 39 studies; animal models and humans: unclear: evidence too weak to tell. consistently improved spatial learning, working memory Early-life cognitive effects of prebiotics and probiotics: A cross-species systematic reviewPubMed 40886953
3. Meta-analysis, 2024; 12 studies, 852 people; adults with mild cognitive impairment or Alzheimer's disease: improves. recall/delayed memory (SMD=0.67; 95% CI: 0.32, 1.02) Effect of probiotics on cognitive function in adults with mild cognitive impairment or Alzheimer's disease: A meta-analysis of randomized controlled trialsPubMed 38641508
4. Meta-analysis, 2023; 10 studies, 702 people; older adults with cognitive impairment: improves. Evaluation of improvement of cognitive impairment in older adults with probiotic supplementation: A systematic review and meta-analysisPubMed 37788563
5. Systematic review, 2016; 38 studies; animals and humans: improves. Effect of Probiotics on Central Nervous System Functions in Animals and Humans: A Systematic ReviewPubMed 27413138
6. Randomised trial, 2022; 59 people; healthy young adults: no clear difference. There were no effects on cognitive performance or mental health. Evidence in favor of the … Effects of a multi-strain probiotic on hippocampal structure and function, cognition, and emotional well-being in healthy individuals: a double-blind randomised-controlled trialPubMed 35513910
7. Randomised trial, 2020; 80 people; older adults with suspected mild cognitive impairment: improves. significant improvement in domain scores of immediate memory Probiotic Bifidobacterium breve in Improving Cognitive Functions of Older Adults with Suspected Mild Cognitive Impairment: A Randomized, Double-Blind, Placebo-Controlled TrialPubMed 32623402
8. Randomised trial, 2019; 103 people; stressed adults with moderate stress: improves. enhanced memory and cognitive traits such as social emotional cognition Probiotic Lactobacillus plantarum P8 alleviated stress and anxiety while enhancing memory and cognition in stressed adults: A randomised, double-blind, placebo-controlled studyPubMed 30266270
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Theanine: memory
The studies read are too weak to tell whether Theanine changes memory. They lean toward an improvement, which is not enough to claim one. The evidence is very weak.
Side effects: 1 of the 3 studies that reported on them found more with Theanine (headache ratings).
4 studies counted of 10 read: 3 trials (27 people in the trials).
1. Randomised trial, 2021; japanese men and women aged 50-69 years: improves. Effects of l-Theanine on Cognitive Function in Middle-Aged and Older Subjects: A Randomized Placebo-Controlled StudyPubMed 33751906
2. Non-randomised trial, 2017; 20 people; patients with major depressive disorder: improves. verbal memory (p=0.005) and executive function Effects of chronic l-theanine administration in patients with major depressive disorder: an open-label studyPubMed 27396868
3. Randomised trial, 2011; elderly persons with normal or slight cognitive dysfunction: improves. showed significantly lower decline in cognitive function Neuroprotective effects of theanine and its preventive effects on cognitive dysfunctionPubMed 21477654
4. Crossover trial, 2008; 27 people; healthy volunteers: improves. reduced susceptibility to distracting information in the memory task The combined effects of L-theanine and caffeine on cognitive performance and moodPubMed 18681988
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.
Vitamin E: memory
A Cochrane review (2018, 1 study, 516 people) found little or no difference in memory. That review studied people with mild cognitive impairment. All 2 studies read agree. The evidence is limited.
2 studies counted of 9 read: 2 reviews.
1. Meta-analysis, 2018; 1 study, 516 people; people with mild cognitive impairment: no clear difference (the review the verdict rests on). no significant effect of three years of supplementation with vitamin E on Vitamin and mineral supplementation for preventing dementia or delaying cognitive decline in people with mild cognitive impairmentPubMed 30383288
2. Systematic review, 2018; 38 studies; adults with normal cognition or mild cognitive impairment: no clear difference. vitamin E had no benefit on cognition Over-the-Counter Supplement Interventions to Prevent Cognitive Decline, Mild Cognitive Impairment, and Clinical Alzheimer-Type Dementia: A Systematic ReviewPubMed 29255909
Automated reading of the published studies (Decosa evidence engine), run 30 Sep 2026. It reads abstracts, can miss studies, and a repeat run can differ.

Key findings

Reaction TimeTea (Camellia sinensis)Improves (the measure goes up)
Cognitive DeclinePiracetamImproves (the measure goes down)
Alzheimer's Disease SymptomsPanax Ginseng (Korean Ginseng)Improves (the measure goes down)

The Cognitive Improvement protocol

2 primary supplements · 5 supporting supplements

Caffeine + L-Theanine100–200 mg caffeine + 100–200 mg L-theanine (1:1 or 1:2 ratio)
Panax Ginseng200–400 mg standardized extract daily

See the full protocol

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Studies cited

13 studies from PubMed

The effects on mental fatigue and the cognitive function of mechanical massage and binaural beats (brain massage) provided by massage chairsComplement Ther Clin Pract · PMID 30057053
Binaural auditory beats affect long-term memoryPsychol Res · PMID 29222722
Binaural auditory beats affect vigilance performance and moodPhysiol Behav · PMID 9423966
The Effects of Binaural and Monoaural Beat Stimulation on Cognitive Functioning in Subjects with Different Levels of EmotionalityAdv Cogn Psychol · PMID 32395188
The effect of binaural beats on verbal working memory and cortical connectivityJ Neural Eng · PMID 28145275
The Effect of Binaural Beats on Visuospatial Working Memory and Cortical ConnectivityPLoS One · PMID 27893766
The impact of binaural beats on creativityFront Hum Neurosci · PMID 24294202
Concord grape juice supplementation and neurocognitive function in human agingJ Agric Food Chem · PMID 22468945
Concord grape juice supplementation improves memory function in older adults with mild cognitive impairmentBr J Nutr · PMID 20028599
Cognitive and mood improvements following acute supplementation with purple grape juice in healthy young adultsEur J Nutr · PMID 28429081
Acute effects of psilocybin on attention and executive functioning in healthy volunteers: a systematic review and multilevel meta-analysis.Psychopharmacology · PMID 39847068
Acute effects of fasting on cognitive performance: A systematic review and meta-analysis.Psychol Bull · PMID 41182703
Omega-3 polyunsaturated fatty acids and cognition in a college-aged populationExp Clin Psychopharmacol · PMID 22250656