Nootropic
Nootropics ( , or ) (colloquial: smart drugs and cognitive enhancers) are drugs, supplements, and other substances that are claimed to improve cognitive function, particularly executive functions, attention, memory, creativity, or motivation, in healthy individuals. The use of cognition-enhancing drugs by healthy individuals in the absence of a medical indication spans numerous controversial issues, including the ethics and fairness of their use, concerns over adverse effects, and the diversion of prescription drugs for non-medical uses. Nonetheless, the international sales of cognition-enhancing supplements have continued to grow over time, and reached .96 billion in 2018. In 2018, some nootropic supplements  in the United States were identified as having misleading ingredients and illegal marketing. In 2019, the US Food and Drug Administration (FDA) and Federal Trade Commission (FTC) warned manufacturers and consumers about possible advertising fraud and marketing scams concerning nootropic supplements. Etymology. The term "nootropic" is derived from the Ancient Greek words ("nóos"), meaning "mind", and ("tropḗ"), meaning "a turning". Illegal marketing claims. Nootropics are frequently advertised with unproven claims of effectiveness at improving cognition. The FDA and FTC warned manufacturers and consumers in 2019 about possible advertising fraud and marketing scams concerning nootropic supplement products. The FDA and FTC  stated that some nootropic products had not been approved as a drug effective for any medical purpose, were not proven to be safe, and were illegally marketed in the United States under violation of the Federal Food, Drug, and Cosmetic Act. Over the years 2010 to 2019, the FDA warned numerous supplement manufacturers about the illegal status of their products as unapproved drugs with no proven safety or efficacy at the doses recommended, together with misleading marketing. Availability and prevalence. In 2008, the most commonly used class of drug was stimulants, such as caffeine. Manufacturers' marketing claims for dietary supplements  are usually not formally tested and verified by independent entities. In 2016, the American Medical Association adopted a policy to discourage prescriptions of nootropics for healthy people, on the basis that the cognitive effects appear to be highly variable among individuals, are dose-dependent, and limited or modest at best. Use by students. The use of prescription stimulants is especially prevalent among students. Surveys suggest that 0.7–4.5% of German students have used cognitive enhancers in their lifetimes.<ref name="doi10.1371/journal.pone.0068821"></ref><ref name="C4WDefault-10.3109/10826084.2012.751426"></ref> Stimulants such as dimethylamylamine and methylphenidate are used on college campuses and by younger groups. Based upon studies of  self-reported illicit stimulant use, of college students use diverted ADHD stimulants, which are primarily used for enhancement of academic performance rather than as recreational drugs. Several factors positively and negatively influence an individual's willingness to use a drug for the purpose of enhancing cognitive performance. Among them are personal characteristics, drug characteristics, and characteristics of the social context.<ref name="C4WDefault-10.1186/1747-597X-9-8"></ref><ref name="PLOS ONE-10.1371/journal.pone.0071452"></ref> Side effects. The main concern with pharmaceutical drugs is adverse effects, which also apply to nootropics with undefined effect. Long-term safety evidence is typically unavailable for nootropics. Racetams, piracetams, and other compounds  that are structurally related to piracetam, have few serious adverse effects and low toxicity, but there is little evidence that they enhance cognition in people having no cognitive impairments. In the United States, dietary supplements may be marketed if the manufacturer can show that the supplement is generally recognized as safe, and if the manufacturer does not make any claims about using the supplement to treat or prevent any disease or condition; supplements that contain drugs or advertise health claims are illegal under US law. Drugs. Central nervous system stimulants. Systematic reviews and meta-analyses of clinical human research using  low doses of certain central nervous system stimulants found that these drugs enhance cognition in healthy people. In particular, the classes of stimulants that demonstrate cognition-enhancing effects in humans act as direct agonists or indirect agonists of dopamine receptor D, adrenoceptor A, or both types of receptor in the prefrontal cortex. Relatively high doses of stimulants cause cognitive deficits. Racetams. Racetams, such as piracetam, oxiracetam, phenylpiracetam, and aniracetam, are often marketed as cognitive enhancers and sold over the counter. A recent study found that piracetam supplements sold in the United States were inaccurately labeled. Racetams are often referred to  as nootropics, but this property is not well established. The racetams have poorly understood mechanisms, although piracetam and aniracetam are known to act as positive allosteric modulators of AMPA receptors and appear to modulate cholinergic systems. According to the US Food and Drug Administration, "Piracetam is not a vitamin, mineral, amino acid, herb or other botanical, or dietary substance for use by humans to supplement the diet by increasing the total dietary intake. Further, piracetam is not a concentrate, metabolite, constituent, extract or combination of any such dietary ingredient. [...] Accordingly, these products are drugs, under section 201(g)(1)(C) of the Act , 21 U.S.C. § 321(g)(1)(C), because they are not foods and they are intended to affect the structure or any function of the body. Moreover, these products are new drugs as defined by section 201(p) of the Act, 21 U.S.C. § 321(p), because they are not generally recognized as safe and effective for use under the conditions prescribed, recommended, or suggested in their labeling." Cholinergics. Some of the most widely used nootropic substances are the cholinergics. These are typically compounds and analogues of choline. Choline is an essential nutrient needed for the synthesis of acetylcholine (a neurotransmitter), and phosphatidylcholine (a structural component of  brain cell membranes). Miscellaneous. The cognitive enhancing effects of pramipexole, guanfacine, clonidine, and fexofenadine have been tested, but no significant cognition-enhancing effects in healthy individuals were found. Psychedelic microdosing is the novel practice of using sub-threshold doses (microdoses) of psychedelic drugs in an attempt to improve mood and cognition. The efficacy of this has not been verified. In a study examining the qualitative reports of 278 microdosers the researchers found that there were mixed results among users. While some users reported positive effects such as improved mood and cognition, others paradoxically reported negative effects such as physiological discomfort  and anxiety. In one of the only double-blind, randomized studies to date, those given microdoses of LSD did not perform better than those given the placebo on cognitive tasks. History. The term "nootropic" was coined by Corneliu Giurgea in 1972 to describe a new classification of molecules that acted selectively towards the brain's higher-level integrative activity. In order for a product to qualify as a true nootropic, it must fulfill Giurgea's five criteria for the category. Nutrients and dietary supplements. A 2015 review found that use of omega-3 fatty acids, B vitamins, and vitamin E as  nootropics was ineffective on cognitive function in normal middle-aged and older people.