BBC article here.
"Exercise 'significant role' in reducing risk of dementia, long-term study finds"
…so keep on doing that thing folks! It'll not only help fight the flab but also protect your brain. It's just one more reason to keep on exercising (as if we needed one!).
Over my many years of training I've found martial artists to be particularly driven in what they do and very often they don't need a 'reason' to go to training; it just happens. It's cold outside, it's raining, you're bored with your training schedule at the moment but still…you go.
And now you can rest assured that it's doing you good in lots of other ways you never thought about before.