Health: Body And Mind

We didn't really need another reason to lose weight, but headlines last week provided one anyway: news that as your body gets larger, your brain may be getting smaller. That's a little overdramatic, to be sure, but it is now probably reasonable to add dementia to the ever growing list of obesity-related illnesses. For some time, researchers have known that carrying a lot of extra weight is not only linked to chronic diseases like arthritis and cancer but may also be a risk factor for brain diseases like Alzheimer's. And now, using sophisticated brain scans, scientists may be a step closer to showing how that works.

Researchers from Göteborg University in Sweden and the Medical College of Wisconsin in Milwaukee followed nearly 300 women over a period of 24 years and then, when the women were between the ages of 70 and 84, performed C.T. scans on their brains. Not surprisingly, body-mass index (or BMI, a ratio of weight to height) increased as the women aged. In addition, the women with the highest BMI turned out to be the most likely to have suffered atrophy, or wasting, of the temporal lobes of the brain. In fact, the researchers found that for every 1-point rise in BMI, the risk of temporal-lobe atrophy increased between 13% and 16%. The temporal lobes, which are often affected in Alzheimer's disease, play a role in memory, verbal expression and language comprehension.

Deborah Gustafson, lead author of the report, which appears in the current issue of Neurology, says there are several possible explanations for fat in the body leading to cell death in the brain. For one thing, being overweight or obese is linked to hypertension, diabetes and high cholesterol, all of which contribute to blocked arteries and decreased blood supply to the brain. "Fat alone," she adds, "could be the problem, as it leads to increased levels of brain-attacking hormones, such as cortisol."

More than 66% of adults in the U.S. and 50% of those in Europe are considered overweight or obese. The impact of this epidemic on the middle-aged is well known, but this study shows it may also contribute to the neuro-degenerative diseases of late life. The good news is that simple interventions now--such as controlling cholesterol, lowering blood pressure, getting checked for diabetes and dropping even a few of those extra pounds--can keep your body and your mind healthier for years to come. --With reporting by Miriam Falco/Atlanta

Sanjay Gupta is a neurosurgeon and CNN medical correspondent