The link between linguistics and dementia

According to this article, those who are bilingual (and use both languages on a daily basis) have a better chance of avoiding (or at least delaying onset of) dementia.  I knew I was supposed to go on a foreign speaking mission!  Ok, so I kind of did.  I served in the California Oakland Mission and loved (almost) every moment of it.

In all seriousness now… the brain is so amazing.  By using different parts of your brain, you are giving it exercise.  In doing so, you prevent it from being susceptible to certain ailments.  It’s much like the rest of your body.  If you work out and exercise, you are less likely to get hurt and are going to be much healthier.

The more interesting part of this study is that the scientists were able to form a correlation between linguistics and dementia.  What other correlations are there?  How does doing math help our health?  Also, can I use an inverse here and say that physical exercise will also help our mental capacities? Does being active help our brain function?  Most would say yes, but is there a study out there that would back it up?  Perhaps I can get some funding to do a study! 😉
I wonder what disease I am staving off by watching TV and working on my computer (at the same time — pretty amazing, huh)?