http://story.news.yahoo.com/news?tmpl=story&cid=97&ncid=97&e=5&u=/hsn/20031126/hl_hsn/mrimaypredictdementiainthehealthy

Check the other links associated with this article. There is even one on THC helping the anxiety seen in some people with advanced dementia.   Of all the neurologic conditions, this is going to be the "numero uno" problem for our generation; due to increasing longevity, and perhaps due to some unknown as yet environmental or genetic factors, the incidence of dementia is skyrocketing. 

G