Researchers at the Brain Sciences Institute, Swinburne University, in Australia gave healthy participants a bacopa extract for 90 days and compared the results to a group of individuals who got placebo pills. The bacopa monnieri product significantly improved memory accuracy. See http://www.raysahelian.com/bacopa.html 
   There are many herbs and nutrients that are potentially beneficial for memory and mental enhancement including acetyl l-carnitine, DMAE, certain B vitamins, fish oils and others. It is difficult to predict in any one individual which nutrient, herb, or combination will provide benefits.