Alzheimer’s risk linked to midlife fat distribution

The risk of developing Alzheimer’s disease late in life may be more closely related to midlife fat distribution than to being overweight or obese overall, according to the results of a large-scale study presented at the annual meeting of the American Academy of Neurology. Researchers used data from almost 9,000 members of the Kaiser Perma-nente Health Plan who underwent a series of tests in 1964-1973 when they were aged 40-45 years. One evaluation included measurement of skinfold thickness using calipers in the sub-scapular and triceps regions. More than 30 years later (between 1994 and 2003), the investigators checked medical records for diagnoses of Alzheimer’s disease (AD).

The findings showed that people in the upper 20% of adiposity in the subscapular region were almost four times more likely to develop AD than were those in the lowest 20%. That risk for individuals in the upper 20% of adiposity on triceps measurements was about 3.5 times greater than that of people in the lowest quintile. Previous research and others have shown that overweight and obesity in middle age increase the future risk of dementia and AD. However, these studies relied on measurement of BMI. The data from the current study, in which calipers were used to measure skinfold, were adjusted for BMI, as well as for common co-morbidities of obesity.

Many of these people in the upper quintile were overweight or obese — but not all of them. Even a person of normal weight in middle age may be more likely to develop AD if he is carrying a centralized truncal distribution of fat.