The researchers studied brain images of 94 people in their 70s who had participated in an earlier study looking at cardiovascular health and cognition. None of the participants had dementia or other cognitive impairments. They were followed for five years, and any volunteers who developed cognitive symptoms were excluded from the study.
Clinically obese people had 8 percent less brain tissue, while the overweight had 4 percent less brain tissue compared to normal-weight individuals.
Dr. Jonathan Friedman, an associate professor of surgery and neuroscience and experimental therapeutics at the Texas A&M Health Science Center College of Medicine noted that the causal relationship here is not clear. Theoretically, he said, a smaller brain might mean appetite and weight-control centers of the brain are actually propelling the weight-gain process.
Thompson believes it may be a vicious cycle. "Each one is contributing to the other," he said. A person's genetics may be contributing to overeating and weight gain, which leads to less activity, which leads to a shortfall in the oxygen and nutrients that the brain needs to thrive and grow.
Overall, though, the findings really weren't surprising, added Dr. Mitchell Roslin, chief of obesity surgery at Lenox Hill Hospital in New York City.
"Obesity affects every system in your body. The body can't be splintered. It's completely linked. We are what we eat and we eat too much," he said. "The bottom line is that an obese, sedentary person is going to have a breakdown of every organ system, and that includes a greater chance of impotence and infertility and other things that people don't generally think are directly related to obesity."
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