Cholinergic

Alpha-GPC (choline alfoscerate) is a choline-containing phospholipid breakdown product, sold as a prescription drug in some countries and a supplement elsewhere. It is a precursor of both choline and acetylcholine. Its record is unusually mixed. One very large Korean cohort linked it to lower dementia conversion, while another linked it to higher 10-year stroke risk.

Citicoline (CDP-choline) is an intermediate in the synthesis of phosphatidylcholine, the main phospholipid in cell membranes. It is a prescription drug in some countries and a supplement in others. A meta-analysis found it improved cognitive status in mild cognitive impairment, Alzheimer's disease and post-stroke dementia, though the underlying studies were of poor quality.

Piracetam is the original "nootropic". C. Giurgea developed it in the late 1960s and coined the word to describe it. It is licensed in several countries for cognitive disorders, vertigo and cortical myoclonus. The evidence is mixed. An older meta-analysis found a global benefit in older adults with cognitive impairment, but a 2024 meta-analysis could not confirm an effect on memory.