July 16, 2003
Need another reason to keep your weight down? Older women who were overweight at age 70 were much more likely to develop Alzheimer's disease 10 to 18 years later, according to the findings of a new Swedish study. The report appeared in the current issue of the Archives of Internal Medicine, a highly respected medical journal for physicians.
Carrying excess weight has been closely linked with diseases that affect the blood vessels, including diabetes, heart disease, and high blood pressure, and there is growing evidence that such vascular ailments may be important risk factors for Alzheimer's as well. In addition, obesity is often associated with disturbances in fat metabolism, such as high cholesterol, says Samuel Gandy, M.D., Ph.D., chairman of the scientific advisory board at the Fisher Center for Alzheimer's Research Foundation.
"Given the evidence that cholesterol controls the buildup of the sticky substance amyloid in the brain, which is thought to lie at the root of Alzheimer's, it will be important to distinguish the association between Alzheimer's, obesity and any underlying disturbances in fat metabolism," comments Dr. Gandy. "For example, it is possible that high cholesterol may underlie some or all of the apparent risk of obesity. Nevertheless, every clue about possible modifiable risk factors for Alzheimer's is exciting for the scientific, medical and lay communities."
Studying the connection between obesity and Alzheimer's has been difficult, in part because people who develop the mind-ravaging ailment frequently lose weight before hallmark symptoms like memory loss and confusion become evident. "Because of the weight loss associated with pre-clinical dementia, it took an extended study to uncover the dangers that overweight may pose to a very elderly population," said Deborah Gustafson, PhD, who conducted the research at Sweden's Gothenburg University.
A Healthy Weight
The researchers followed 392 seniors for 18 years, beginning when they were 70 years old, and assessed a standard measure of body fat that takes into account both height and weight called the Body Mass Index, or BMI. The National Institutes of Health has a handy BMI calculator . A BMI of 18 to 25 is considered normal weight; 25 to 30 overweight; and 30 and above obese. A woman who is 5 feet 4 inches tall and weighs 170 pounds, for example, has a BMI of 29. Women who developed Alzheimer's at age 75 or older were significantly more likely to have been heavier at age 70 than those whose minds remained intact, with BMIs that were, on average, 3.6 units higher than their lower-weight counterparts. Each point increase in the BMI after age 70 led to a 36 percent increase in Alzheimer's risk.
"It's important to note that the ideal weight is not super-skinny," said Dr. Gustafson. "The average BMI for women who did not develop Alzheimer's disease was 25, the border between healthy and overweight. A moderate, healthy weight seems to be best." The study is part of an ongoing long-term research project of older men and women that began in Sweden in 1970. However, there were not enough men enrolled in the trial to draw definitive conclusions. Furthermore, the research did not examine that effects of being overweight at a younger age, say 50 or 60, although excess weight at any age can has been linked to numerous health problems, including high blood pressure and heart disease.
Age remains the most important risk factor for Alzheimer's: The older you are, the more likely you are to develop the disease. Smoking, high blood pressure, years of schooling, and genetic factors may also contribute to risk, other research has shown. Still, as the results of this study suggest, keeping your weight down in your senior years may help you to remain mentally alert as well.
By Toby Bilanow, Medical Writer, for www.ALZinfo.org. The Alzheimer's Information Site. Reviewed by Samuel E. Gandy, M.D., Ph.D., Chairman of the Scientific Advisory Board, Fisher Center for Alzheimer's Research Foundation.