Obese Middle-Aged Adults And Underweight Older Adults Appear To Have Increased Risk For Dementia

Main Category: Obesity / Weight Loss / Fitness
Also Included In: Alzheimer's / Dementia;  Neurology / Neuroscience
Article Date: 09 Mar 2009 - 13:00 PDT

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Midlife obesity may be associated with risk for dementia, but after age 65, the relationship between body mass index and dementia appears to reverse so that underweight individuals are at higher risk. Annette L. Fitzpatrick, Ph.D., of the University of Washington, Seattle, and colleagues analyzed data from 2,798 adults (average age 74.7) without dementia. Participants reported their weight at age 50 (midlife) and had their height and weight measured at age 65 or older (late life).

Over an average of 5.4 years of follow-up, 480 individuals developed dementia, including 245 with Alzheimer's disease and 213 with vascular dementia. In evaluations of midlife obesity, individuals with a body mass index (BMI) of higher than 30-classified as obese-were more likely than those of a normal weight to develop dementia. However, those who were underweight (BMI of lower than 20) in late life had an increased risk of dementia, whereas being overweight in late life was not associated with dementia and being obese appeared to have a protective effect.

"The greatest dementia risk was found in underweight individuals at older ages. These findings suggest the predictive ability of BMI changes across time," the authors write. "These results help explain the 'obesity paradox' as differences in dementia risk across time are consistent with physical changes in the trajectory toward disability."

Arch Neurol. 2009;66[3]:336-342.

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