Some years ago, researchers noticed that people with severe arthritis have strikingly low rates of Alzheimer's disease. More recently, Japanese researchers noted a similar unusually low rate of Alzheimer's disease in people being treated for leprosy.

Compared with men, women are at greater risk of developing Alzheimer's disease. But recent studies show that they also have a treatment option unavailable to most men -- the female sex hormone estrogen, which helps prevent, delay, and treat Alzheimer's disease.

Eat more fruits and vegetables. Take antioxidants. We humans need oxygen to live, but oxygen also has a downside. In the body, some oxygen molecules become so highly chemically reactive that they disrupt other body processes. These troublemaker molecules are called "free radicals," and many scientists believe that the damage they inflict (oxidative damage)

Perhaps you've heard that the typical adult loses some 10,000 brain cells a day. The implication is that by the time we qualify for Social Security, there's not much left between our ears. On the contrary: The brain contains hundreds of billions of neurons, giving us reasoning and memory capabilities that in many ways dwarf the most sophisticated supercomputer.