Certain B vitamins - B6, B12 and folic acid - are known to reduce levels of a compound called homocysteine in the blood. Elevated levels of homocysteine are associated with increased risk of stroke, cognitive impairment and Alzheimer's disease. A study of a group of elderly patients with mild cognitive impairment found that after two years of intervention with high doses of B6, B12 and folic acid there was significantly less brain shrinkage compared to a subset given placebo treatment. Opt for B-rich foods like eggs, chicken, fish and leafy greens.
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 nonmedical uses, among others. Nonetheless, the international sales of cognition-enhancing supplements exceeded US$1 billion in 2015 when global demand for these compounds grew.