Boston University Researcher Identifies Obesity as New Risk Factor for Lowered Cognitive Function

in Health & Medicine, News Releases
March 26th, 2003

Contact: Ann Marie Menting, 617/353-2240 | amenting@bu.edu

(Boston, Mass.) — The list of risk factors that contribute to cognitive deficit should now include obesity, according to research reported by Merrill Elias, research professor of epidemiology at Boston University, in the February 2003 International Journal of Obesity.

Elias, a member of the Statistics and Consulting Unit of BU’s Department of Mathematics and Statistics, and his co-investigators at the Framingham Heart Study are the first to show that long-term, early-onset obesity is an independent risk factor to cognitive dysfunction. This knowledge should help inform physician–patient decisions to treat this physical condition.

Previously established risk factors for lowered cognitive function include cardiovascular disease (CVD), high cholesterol, and hypertension. Research on obesity as a potential risk factor has been limited to only a few studies that, although showing lowered cognitive functioning in men, have not measured obesity’s role independent of established risk factors.

Elias and his colleagues designed their study to address this issue. They measured whether hypertension and obesity, known risk factors for CVD, were associated independently or in combination with lowered cognitive functioning in men and women who were free from both CVD and dementia.

The investigators used data gathered in the Framingham Heart Study, an ongoing investigation begun in 1948. Elias’ study included data for 1,423 people (551 men and 872 women). This number was honed from a possible 2,123 Framingham participants to ensure the study data would exclude individuals with known risk factors for cognitive dysfunction.

For Elias’s study, obesity was defined according to measures for body mass index, a calculation of total body fat based on a person’s weight and height, established by the National Heart, Lung, and Blood Institute. Hypertension was defined as blood pressure equal to or greater than the commonly accepted national standard of 140/90. Measures for cognitive functioning included those for executive functioning, which measures planning and organizational ability, and abstract reasoning.

Analyses of these data by the researchers found that the combination of obesity and hypertension showed a statistically significant association with the cognitive functioning of men, but not of women. Among late middle-aged and elderly men, obesity and hypertension were associated with lowered cognitive functioning. Among all men, the effects of obesity and hypertension were found to be cumulative, with cognitive functioning lowered more when both conditions were present than when one or neither was a factor. The researchers speculated that obesity and hypertension may have similar physiological “paths” by which they affect cognitive functioning and that the different distribution of fat on men and women may help to explain the adverse effects of obesity in men compared to women.

“These results have potentially important implications for encouraging persons with obesity, hypertension, or both to seek treatment and stay on prescribed treatment regimens,” says Elias. “People really want to maintain their cognitive functioning as they age. The possibility that there are conditions that, if controlled through treatment, would help reduce their risk for cognitive dysfunction, should be encouraging to patients and their physicians.”

Framingham Heart Study researchers have gathered data on CVD for more than five decades from people recruited from the community of Framingham, Mass. These data, available for ongoing analysis by researchers, have provided insights into treatments for CVD and into the complex physical and behavioral relationships that influence long-term health and well-being.

The Department of Mathematics and Statistics at Boston University offers a strong research environment in algebra, applied statistics, dynamical systems and their applications, geometry, mathematical neuroscience and biology, mathematical physics, number theory, partial differential equations, and probability. Programs for specialized applications are the Statistics and Consulting Unit and the Center for Biodynamics.

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