Perhaps the most well-known natural nootropic stimulant and neuroenhancer is caffeine. Caffeine has been shown to prevent memory deficits in experimental models of Alzheimer’s disease and may even restore memory following impairment. In studies performed with college students, caffeine was shown to have particularly potent effects on memory improvement during students’ non-optimal time of day, in this case, early in the morning. Caffeine’s benefits go even further because it’s never found in an isolated vacuum in nature, meaning that it’s always located in some kind of plant such as green tea or bean such as coffee that carry additional beneficial compounds which often enhance the effects of caffeine, including, most notably, certain cholesterols, polyphenols and antioxidants. In fact, one study determined that caffeine alone does not account for the benefits caused by coffee consumption. Rather, the phytochemical content of coffee (coffee contains over 1,000 different natural chemicals!) gives it potent antioxidant and anti-inflammatory properties that complement the neuroprotective effects of caffeine on the central nervous system.
The main concern with pharmaceutical drugs is adverse effects, which also apply to nootropics with undefined effects. Long-term safety evidence is typically unavailable for nootropics. Racetams — piracetam 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.