Noopept is a popular cognitive-enhancing supplement in the nootropic community. Proposed mechanism of actions based on preclinical studies include increasing acetylcholine signaling, increasing the expression of BDNF and NGF, protecting from glutamate toxicity, and increasing inhibitory neurotransmission in the brain.
Source: https://www.alzdiscovery.org/uploads/cognitive_vitality_media/Noopept-Cognitive-Vitality-For-Researchers.pdf