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A general blanket statement referring to the abilities of the mind to pass tests put on it. Shares components of a lot of other cognitive phenomena, and not to be confused with Memory, Attention, or Anxiety.

Research analysis lead by Kamal Patel
All content reviewed by Examine.com Team. Published:
Last Updated:

Human Effect Matrix

The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what supplements affect cognition
Grade Level of Evidence
Robust research conducted with repeated double-blind clinical trials
Multiple studies where at least two are double-blind and placebo controlled
Single double-blind study or multiple cohort studies
Uncontrolled or observational studies only
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Outcome Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
grade-b Rhodiola Rosea Notable Very High See all 4 studies
Notably effective assuming fatigue is being reduced. There is insufficient evidence to evaluate rhodiola's effects on cognition without the fatigue reduction aspect
grade-b D-Serine Minor High See all 3 studies
There may be an improvement in cognitive performance secondary to reducing symptoms of schizophrenia, and while there is mechanistic plausibility that this can also work in normal controls it has not yet been demonstrated
grade-b Ginkgo biloba Minor High See all 7 studies
Other parameters of cognition are differentially influenced by ginkgo, as facial recognition in those with dementia has noted improvement yet trip planning in middle-aged persons is unaffected.
grade-b L-Tyrosine  
grade-b Modafinil  
grade-b Panax ginseng  
grade-b Phosphatidylserine  
grade-c Glycine  
grade-c Green Tea Catechins  
grade-c Kava  
grade-c L-Carnitine  
grade-c Nicotine  
grade-c Nigella sativa  
grade-c Phenylpiracetam  
grade-c Pycnogenol  
grade-c Sceletium tortuosum  
grade-c Zinc  
grade-c Bacopa monnieri  
grade-c Black Cohosh  
grade-c Choline  
grade-c Cocoa Extract  
grade-c Dehydroepiandrosterone  
grade-c Marijuana  
grade-c Resveratrol  
grade-c Sarcosine  
grade-d Pramiracetam  
grade-d Pueraria lobata  
grade-d Piracetam  

All comparative evidence is now gathered in our ​A-to-Z Supplement Reference.

The evidence for each separate supplement is still freely available ​here.