Omega-3 fatty acids: DHA and EPA – two Cochrane Collaboration reviews on the use of supplemental omega-3 fatty acids for ADHD and learning disorders conclude that there is limited evidence of treatment benefits for either disorder.[42][43] Two other systematic reviews noted no cognition-enhancing effects in the general population or middle-aged and older adults.[44][45]
Traditional Chinese medicine also has a long, well-established relationship with nootropic herbs and plants. One of the most popular and well-known is ginkgo biloba, derived from the Chinese maidenhair tree, a relic of the ancient world. The maidenhair tree is the last living species of the division Ginkgophyta>. Some believe that the name ginkgo is a misspelling of the original Japanese gin kyo, meaning “silver apricot”. It’s seen as a symbol of longevity and vitality and is known to be effective at stimulating the growth of new neurons. Researchers have demonstrated that ginkgo flavonoids, the main constituents in ginkgo extract, provide potent anti-Alzheimer’s effects via antioxidant activity in the brains of mice and also stabilize and improve the cognitive performance of Alzheimer patients for 6 months to 1 year. Effective doses range from 120 to 240 mg one to four hours before performance, and for older adults, doses range from 40 to 120 mg three times a day.
Jump up ^ Weyandt LL, Oster DR, Marraccini ME, Gudmundsdottir BG, Munro BA, Zavras BM, Kuhar B (September 2014). "Pharmacological interventions for adolescents and adults with ADHD: stimulant and nonstimulant medications and misuse of prescription stimulants". Psychol. Res. Behav. Manag. 7: 223–249. doi:10.2147/PRBM.S47013. PMC 4164338. PMID 25228824.
Systematic reviews and meta-analyses of clinical human research using low doses of certain central nervous system stimulants found enhanced cognition in healthy people.[21][22][23] In particular, the classes of stimulants that demonstrate cognition-enhancing effects in humans act as direct agonists or indirect agonists of dopamine receptor D1, adrenoceptor A2, or both types of receptor in the prefrontal cortex.[21][22][24][25] Relatively high doses of stimulants cause cognitive deficits.[24][25]