Specific nootropics affect different parts of the brain in their own ways. Some — like caffeine — reduce fatigue by blocking adenosine receptors, while others act to protect neural connections that are already present while possibly contributing to new neural growth.Moreno-Jiménez, E.P., Flor-García, M., Terreros-Roncal, J. et al. Adult hippocampal neurogenesis is abundant in neurologically healthy subjects and drops sharply in patients with Alzheimer’s disease. Nat Med 25, 554–560 (2019). https://doi.org/10.1038/s41591-019-0375-9 Some also mitigate depression and anxiety, which frees up the brain to perform at its best.