Although too many of us to count have been touched in some way by either cancer or Alzheimer's, you've rarely heard of both diseases affecting the same individual. And, at least among Caucasians, there's evidence that suggests a protective link between the two, based on a review of 3,020 seniors (age 65-older).

More than 160 and 522 patients had already been diagnosed with Alzheimer's or cancer, respectively, at the beginning, and roughly 850 more patients developed one condition or the other during the course of the study. Surprisingly, the risk of a future bout with cancer among patients who had been diagnosed with Alzheimer's disease at the start of the study dropped by an amazing 69 percent compared to folks who didn't have the mind-robbing disease in the beginning. And, among Caucasian patients, those who were already fighting cancer at the outset of the study were 43 percent less likely to succumb to Alzheimer's

The same didn't hold true for patients of color, however, specifically for folks treated for cancer at the beginning of the study who had a greater risk of developing Alzheimer's. Even though this finding sounds very distressing, researchers played down its significance due to the low number of patients tracked (29).

All that said, these findings tended to support previous studies that found brain degenerative diseases like Alzheimer's or Parkinson's disease may share some of the same molecular underpinnings with cancer. These interesting connections could partly explain why an existing cancer drug may be used to fight Alzheimer's some day.

Neurology December 23, 2009

ABC News December 23, 2009

EurekAlert December 23, 2009