Kaiser Permanente study shows that a larger abdomen in midlife increases risk of dementia

Researchers studied 6,583 people age 40 to 45 in northern California who had their abdominal density measured. Belly fat was measured by using a caliper to determine the distance from the back to the upper abdomen, midway between the top of the pelvis and the bottom of the ribs. Belly density is highly correlated with visceral fat tissue, the fat tissue that is wrapped around the organs, according to the researchers. An average of 36 years later, 16 percent of the participants had been diagnosed with dementia.

The study found that those who were overweight and had a large belly were 2.3 times more likely to develop dementia than people with a normal weight and belly size. People who were both obese and had a large belly were 3.6 times more likely to develop dementia than those of normal weight and belly size. Those who were overweight or obese but did not have a large abdomen had an 80-percent increased risk of dementia.

Having a large abdomen increased the risk of dementia regardless of whether the participants were of normal weight overall, overweight, or obese, and regardless of existing health conditions, including diabetes, stroke and cardiovascular disease.

Non-whites, smokers, people with high blood pressure, high cholesterol or diabetes, and those with less than a high school level of education were more likely to have abdominal obesity.

As with all observational studies, it is possible that the association of the abdominal obesity and dementia is not driven by the abdominal obesity, but rather by a complex set of health-related behaviors, for which abdominal obesity is but one part.

Additional authors on the study include Deborah R. Gustafson, Ph.D., Goteberg University, Goteberg, Sweden; Elizabeth Barrett-Connor, MD, department of family medicine, University of California, La Jolla, Calif.; Mary N. Haan, DrPH, department of epidemiology, University of Michigan, Ann Arbor, Mich.; Erica P. Gunderson, Ph.D., Kaiser Permanente Division of Research, Oakland, Calif.; and Kristine Yaffe, MD, Departments of Psychiatry, Neurology and Epidemiology, University of California, San Francisco. Funding for the study was provided by the National Institutes of Health.