Have coffee. In an amazing flip-flop, coffee is the new brain tonic. A large European study showed that drinking three to five cups of coffee a day in midlife cut Alzheimers risk 65% in late life. University of South Florida researcher Gary Arendash credits caffeine: He says it reduces dementia-causing amyloid in animal brains. Others credit coffees antioxidants. So drink up, Arendash advises, unless your doctor says you shouldnt.