Apr 24, 2010 11:32 AM by NBC
A third of Americans are estimated to carry a genetic variant that experts say makes them more vulnerable to obesity and Alzheimer's disease.
UCLA researchers studied brain scans of more than 200 elderly adults, and found reduced brain volume in carriers of the genetic variant.
The gene that carries the genetic variant is also linked to greater fat mass.
However, researchers say switching to a low fat diet and exercising can help shed extra pounds and reduce the risk for dementia.