http://opinionator.blogs.nytimes.com/2010/04/20/brain-damage/

That, at least, is the gloomy conclusion of several recent studies. For example, one long-term study of more than 6,500 people in northern California found that those who were fat around the middle at age 40 were more likely to succumb to dementia in their 70s. A long-term study in Sweden found that, compared to thinner people, those who were overweight in their 40s experienced a more rapid, and more pronounced, decline in brain function over the next several decades.

http://www.technologyreview.com/biomedicine/24870/?a=f

“Just five years ago, scientists at Stanford University discovered that neurons injected with a photo-sensitive gene from algae could be turned on or off with the flip of a light switch. This discovery has since turned hundreds of labs onto the young field of optogenetics. Today researchers around the world are using these genetic light switches to control specific neurons in live animals, observing their roles in a growing array of brain functions and diseases, including memory, addiction, depression, Parkinson’s disease, and spinal cord injury.”