Cognition Research Analysis

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 [show legend]
	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

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.	Notes
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
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
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.
L-Tyrosine
Modafinil
Panax ginseng
Phosphatidylserine
Glycine
Green Tea Catechins
Kava
L-Carnitine
Nicotine
Nigella sativa
Phenylpiracetam
Pycnogenol
Sceletium tortuosum
Zinc
Bacopa monnieri
Black Cohosh
Choline
Cocoa Extract
Dehydroepiandrosterone
Marijuana
Resveratrol
Sarcosine
Pramiracetam
Pueraria lobata
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.