Preventing Alzheimer's disease?

Professor Dennis Selkoe points out that although Alzheimer's disease is primarily a genetic disease, environmental factors may be preventative.

Another factor may be the phenomenon of ‘use it or lose it’; perhaps if you use your mind, use your brain (which we encourage everyone to do of course) a lot throughout your life, you are less likely to get Alzheimer’s [disease]. But what’s the chicken and what’s the egg here? It really is a chicken and egg problem; maybe it is the people who are able to use their minds quite effectively, have challenging occupations and do important things with their brainpower. They already have such a good physiological reserve in the brain that even if they were to get Alzheimer’s disease, they resist its badness, so to speak. Or is it the other way around; is it the cart before the horse, and that is that by training their mind to do a lot of complicated stuff throughout their lives and work in intellectually challenging fields, then they build up their reserves. So we don’t know which one it is. The reserve is there from the beginning at birth or during development and that resists Alzheimer’s [disease], or the person who happens to be interested in doing a lot of work with their mind builds up a resistance, and it might well be both. Although scientists like myself were skeptical of the 'use it or lose it' idea, we’re starting to see some evidence of that in animal work and even in human psychology.