The difference in standard deviations is not, from a theoretical perspective, all that strange a phenomenon: at the very beginning of this page, I covered some basic principles of nootropics and mentioned how many stimulants or supplements follow a inverted U-curve where too much or too little lead to poorer performance (ironically, one of the examples in Kruschke 2012 was a smart drug which did not affect means but increased standard deviations).
Farah was one of several scholars who contributed to a recent article in Nature, "Towards Responsible Use of Cognitive Enhancing Drugs by the Healthy". The optimistic tone of the article suggested that some bioethicists are leaning towards endorsing neuroenhancement. "Like all new technologies, cognitive enhancement can be used well or poorly," the article declared. "We should welcome new methods of improving our brain function. In a world in which human workspans and lifespans are increasing, cognitive-enhancement tools - including the pharmacological - will be increasingly useful for improved quality of life and extended work productivity, as well as to stave off normal and pathological age-related cognitive declines. Safe and effective cognitive enhancers will benefit both the individual and society." The BMA report offered a similarly upbeat observation: "Universal access to enhancing interventions would bring up the baseline level of cognitive ability, which is generally seen to be a good thing."
A key area that has been widely researched is the link between the microbiome (bacteria) in the gut and the brain. The hypothesis is that alterations in bacteria due to changes in our environment such as increased hygiene, increased exposure to antibiotics, refined and processed foods and stress have led to disturbances in short-chain fatty acids (SFCAs), which are byproducts of fermentation in the gut when bacteria come into contact with indigestible fibre found in food.
Subjects with a history or presence of clinically important cardiac, renal, hepatic, endocrine (including diabetes mellitus), pulmonary, biliary, gastrointestinal, pancreatic, or neurologic disorders that, in the judgment of the Investigator, would interfere with the subject's ability to provide informed consent, comply with the study protocol (which might confound the interpretation of the study results), or put the subject at undue risk.
Googling, you sometimes see correlational studies like Intake of Flavonoid-Rich Wine, Tea, and Chocolate by Elderly Men and Women Is Associated with Better Cognitive Test Performance; in this one, the correlated performance increase from eating chocolate was generally fairly modest (say, <10%), and the maximum effects were at 10g/day of what was probably milk chocolate, which generally has 10-40% chocolate liquor in it, suggesting any experiment use 1-4g. More interesting is the blind RCT experiment Consumption of cocoa flavanols results in acute improvements in mood and cognitive performance during sustained mental effort11, which found improvements at ~1g; the most dramatic improvement of the 4 tasks (on the Threes correct) saw a difference of 2 to 6 at the end of the hour of testing, while several of the other tests converged by the end or saw the controls winning (Sevens correct). Crews et al 2008 found no cognitive benefit, and an fMRI experiment found the change in brain oxygen levels it wanted but no improvement to reaction times.
Dallas Michael Cyr, a 41-year-old life coach and business mentor in San Diego, California, also says he experienced a mental improvement when he regularly took another product called Qualia Mind, which its makers say enhances focus, energy, mental clarity, memory and even creativity and mood. "One of the biggest things I noticed was it was much more difficult to be distracted," says Cyr, who took the supplements for about six months but felt their effects last longer. While he's naturally great at starting projects and tasks, the product allowed him to be a "great finisher" too, he says.
As a general class, nootropics are not usually addiction-forming. Two of the strongest hallmarks of addiction-forming drugs is that they cause users to develop dependency and experience withdrawal when the drug use is eliminated or reduced. While there are some reports of nootropic users experiencing brain fog after use is discontinued, these side effects are not considered to be akin to withdrawal effects of addiction-forming drugs.
Nootropics (/noʊ.əˈtrɒpɪks/ noh-ə-TROP-iks) (colloquial: smart drugs and cognitive enhancers) are drugs, supplements, and other substances that may improve cognitive function, particularly executive functions, memory, creativity, or motivation, in healthy individuals. While many substances are purported to improve cognition, research is at a preliminary stage as of 2018, and the effects of the majority of these agents are not fully determined.