A new study investigates the relationship between body mass index and the development of Alzheimer’s disease.

Some studies have discovered people who are overweight in middle age are more likely to develop Alzheimer’s disease decades later than people at normal weight. Additional studies have found that people in the earliest stages of Alzheimer’s disease are more likely to have a lower body mass index (BMI).

In the new investigation, researchers examined 506 people using advanced brain imaging techniques and cerebrospinal fluid analysis to look for Alzheimer’s disease biomarkers. These biomarkers can be present years before the first symptoms.

Study participants included people with no memory problems, people with mild cognitive impairment, or mild memory problems, and people with Alzheimer’s disease.

Researchers discovered a link between Alzheimer’s biomarkers and a lower BMI in people with no memory or thinking problems and in people with mild cognitive impairment.

For example, 85 percent of the people with mild cognitive impairment who had a BMI below 25 had signs of the beta-amyloid plaques in their brains that are a hallmark of the disease, compared to 48 percent of those with mild cognitive impairment who were overweight.

“These results suggest Alzheimer’s disease brain changes are associated with systemic metabolic changes in the very earliest phases of the disease,” said study author Jeffrey M. Burns, M.D., M.S. “This might be due to damage in the area of the brain called the hypothalamus that plays a role in regulating energy metabolism and food intake.

“Further studies should investigate whether this relationship reflects a systemic response to an unrecognized disease or a long-standing trait that predisposes a person to developing the disease.”

The study will be published in the print issue of Neurology.

Source: American Academy of Neurology