How does alzheimer's disease start?

$64K question: We really still don't know how Alzheimer's disease starts, much less, how to cure it. Current medications only slow down progression of symptoms. In fact, we still debate whether plaques or tangles are cause or effect. Check out http://www.alz.org/braintour/plaques_tangles.asp for basics. We do know that heart healthy folks have lower risk so one way to avoid AD is to take care of your heart.