Women who are significantly overweight at age 70 have a substantially increased risk of developing Alzheimer’s disease later in life, according to a long-term study reported in the July 14, 2003 issue of the Archives of Internal Medicine. The work was funded in part by an Alzheimer’s Association Zenith Fellows Award to principal investigator Ingmar Skoog, MD, PhD.
“It is important to note that the average size of the women in this study who did not develop Alzheimer’s was not ‘super-skinny,’ the average was on the borderline between normal and overweight,” notes Deborah Gustafson, PhD, corresponding author. “These results suggest that even moderate, common-sense weight control may help lower risk of Alzheimer’s disease.”
Researchers studied a representative sample of 70-year-old residents of Göteborg, Sweden, for up to 18 years to assess the possible impact of weight on dementia risk. They found that women who developed Alzheimer’s disease between the ages of 79 and 88 were more likely to have been significantly overweight at ages 70, 75, and 79 than those who did not develop dementia.
The women who developed Alzheimer’s disease were significantly heavier than their dementia-free counterparts in terms of body mass index (BMI), a measure of weight in relation to height. BMI can be calculated by dividing weight in kilograms by height in meters squared or by dividing weight in pounds by height in inches squared and multiplying the result by 703. For example, a woman 5 feet 4 inches (64 inches) tall who weighs 170 pounds has a BMI of about 29.
A BMI below 18.5 is considered underweight. A value between 18.5 and 24.9 is considered normal, while the range from 25 to 29.9 is considered overweight. A BMI greater than 30 is defined as obese.
In the Göteborg study, women who had a BMI greater than 29 when they were 70 years old were more likely to develop Alzheimer’s disease in their 80s. The average BMI for women who did not develop Alzheimer’s was 25. On average, every unit increase in BMI at age 70 raised the risk of developing Alzheimer’s disease by about 36 percent.
This study did not find a connection between excess weight and Alzheimer’s in men. The investigators note that one possible explanation may be that fewer male participants survived for the entire 18-year span of the study. Since the likelihood of developing dementia increases with advancing age, fewer men developed dementia because they didn’t tend to live as long as the women. The researchers say that it is also possible that there may be some physiological basis for the difference, such as a metabolic factor or a different pattern of body fat distribution in men and women.
The Centers for Disease Control and Prevention (CDC) provides an on-line calculator that computes BMI using either inches and pounds or meters and kilograms at http://www.cdc.gov/nccdphp/dnpa/bmi/calc-bmi.htm.
Source: The Alzheimer’s Association. Online at www.alz.org.