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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 led by Kamal Patel.
All content reviewed by the Examine.com Team. Published: Feb 6, 2013
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 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 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 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 Minor Very High See all 3 studies
Tyrosine appears to effectively improve cognition during acute stressors (altitude and cold being tested most); this appears reliable if the acute stressor is present, but may not be an inherent increase in cognition and it is unsure if it applies to chronic stress and fatigue.
grade-b Minor High See all 4 studies
Cognition is significantly improved in persons undergoing sleep deprivation or other conditions in which attention processing is highly impaired, while other conditions (cognitive decline or drug dependence) experience minor improvements in cognition that are lesser than those seen in sleep deprivation.
grade-b Minor High See all 4 studies
An increase in cognition is seen acutely and thought to be due to anti-fatigue effects, with nonfatigued individuals not experiencing an increase in cognitive performance
grade-b Minor High See all 3 studies
The interactions of supplemental PS with cognition in healthy persons is not fully researched, but there appears to be a positive influence; this may be secondary to a reduction in stress and excitation (the latter resulting in an increase in attention) but increased glucose utilization is an unexplored possibility
grade-c Minor Very High See 2 studies
There are improvements in cognition due to glycine being able to treat schizophrenia and due to glycine being able to improve sleep; two states of impaired cognition.
grade-c Minor Moderate See 2 studies
Mixed results, but may improve cognitive performance acutely in persons with poorer cognition at baseline
grade-c Minor - See study
Possibly secondary to the antianxiety effects, kava taken prior to a test is able to enhance cognition related to mood during the stressful test.
grade-c Minor Very High See 2 studies
Improvements in general cognitive capacity has been noted in elderly persons and in disease models (hepatic encepalopathy); lack of literature on otherwise healthy youth
grade-c Minor - See study
An improvement in cognition has been noted in persons with mild cognitive impairment
grade-c Minor - See study
A slight improvement in cognition has been noted with supplementation of nigella seed extract in older persons
grade-c Minor Very High See all 3 studies
Cognition is improved in persons suffering from cognitive decline, organic brain lesions, and epilepsy. There are currently no studies conducted in otherwise healthy youth for the purpose of cognitive enhancement
grade-c Minor - See study
An improvement in cognitive function has been noted in students during academic testing
grade-c Minor - See study
A general increase in cognition has been noted with Kanna usage prior to testing in otherwise healthy middle-aged adults, potentially related to the reduction in state anxiety during testing.
grade-c Minor Very High See 2 studies
An improvement in cognition has been seen in stroke patients given zinc to complement their zinc insufficient diet.
grade-c - - See study
No significant influences noted on acute cognitive performance with bacopa monnieri ingestion
grade-c - - See study
No significant influences on cognition in menopausal women has been noted
grade-c - - See study
Acute ingestion of choline does not appear to per se influence cognitive capacity
grade-c - - See study
General cognition does not appear to be acutely affected by supplementation of cocoa flavanols.
grade-c - - See study
Overall cognition not affected by DHEA supplementation
grade-c - - See study
When used during multiple sclerosis, a general battery of cognitive function does not appear to be greatly influenced (positive or negative) with marijuana therapy.
grade-c - - See study
No significant influence on cognition in otherwise healthy persons (despite an increase in cerebral blood flow)
grade-c - - See 2 studies
grade-d Minor - See study
Reaction time on various cognitive tests was improved in people taking 1,000 mg of an ashwagandha extract, but accuracy wasn't.
grade-d Minor - See study
Cognitive ability in youth who experienced brain trauma is improved with prolonged usage of pramiracetam, suggesting neuroprotective effects
grade-d Minor - See study
A small boost in cognition in menopausal women given the supplement; needs to be replicated and uncertain if it applies to otherwise healthy youth.
grade-d - - See study
No significant influence on cognition and neural functioning has been noted in otherwise healthy persons following piracetam ingestion.