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THE SKINNY ON OBESITY AND DIETARY RISK FACTORS FOR ALZHEIMER'S DISEASE
SAN DIEGO—SAN DIEGO—People who are overweight or obese in middle age have a higher risk of Alzheimer’s disease later in life, reported Rachel Whitmer, PhD, at the 58th Annual Meeting of the American Academy of Neurology. Although the finding needs to be confirmed, it "suggests that keeping your weight down in midlife can help you remain mentally alert later on in life," she said.
Unlike previous studies that have traditionally used BMI as a marker for obesity, the current study used measurements of adiposity. "BMI, in general, is a good marker for people who are very overweight, but it doesn’t really take into account where fat clusters on the body," remarked Dr. Whitmer. Skinfold measurement, on the other hand, helps determine "how much fat you might have in a certain area." Until now, regional variation in adiposity had not been examined in relation to Alzheimer’s disease, she noted. Dr. Whitmer is a Research Scientist in the Division of Research at Kaiser Permanente in Oakland, California.
MEASURING SKINFOLD THICKNESS
A total of 8,776 men and women underwent health evaluations between 1964 and 1973 when they were between the ages of 40 and 45. Skinfold measurements were obtained with the use of Lange skinfold calipers, and Alzheimer’s disease diagnoses were determined from medical records from 1994 to 2003.
Dr. Whitmer reported that during an average follow-up period of 27 years, 221 participants were diagnosed with Alzheimer’s disease. Skinfold thickness in both the subscapular and triceps regions was associated with risk of Alzheimer’s disease in a dose-dependent manner. Compared with subjects in the first quintile, those in the fifth quintile of subscapular skinfold thickness (ie, those with the greatest skinfold thickness) had a 2.93-fold increased risk of Alzheimer’s disease, while those in the fifth quintile of triceps skinfold thickness had a 2.55-fold increased risk of Alzheimer’s disease. This association was observed independently of age, gender, race, education, BMI, smoking status, alcohol use, marital status, and the presence of comorbid conditions such as diabetes, hypertension, hyperlipidemia, stroke, and ischemic heart disease.
A "TAKE-HOME MESSAGE"
"These findings are important, because obesity and overweight [status] are treatable and modifiable risk factors," said Dr. Whitmer. She noted that losing and managing weight might reduce the risk of Alzheimer’s disease. "The implication from the study is just that," she said.
"I think the most important take-home message is that people do need to be thinking about their weight even in middle age…. I think it’s important to remind people that keeping a good weight is not only good for the heart—it’s good for the brain, and it will have beneficial effects for you at the end of your life," said Dr. Whitmer. "Even if you’re of normal weight, if you’re carrying a lot of fat in certain areas, that’s not good."
She added, "If we don’t control the current epidemic of obesity, the number of cases of dementia in the future may increase even more than is currently predicted."
UNANSWERED QUESTIONS
According to Dr. Whitmer, "There has been a lot of epidemiologic work looking at nutrition and risk of Alzheimer’s disease. Certainly, people who are overweight don’t have the same dietary habits as people who are of normal weight." There has also been work looking at physical activity, she said, noting that people who are very active have a lower risk of Alzheimer’s disease. She and her team plan to investigate whether changes in adiposity that reflect weight loss might decrease the risk of Alzheimer’s disease.
In addition, "future studies should examine molecular mechanisms between adiposity and development of Alzheimer’s disease," she said. Dr. Whitmer and her colleagues are currently investigating several inflammatory markers in adipocytokines. Key questions that they will try to answer include: What are the effects of the fat cell on the blood-brain barrier? and What are the effects of these adipocytokines on cognitive functioning and memory? "We’re really trying to focus on the role of the hormones that are secreted by the fat cell and what they actually do," she said.
Dr. Whitmer also noted that efforts to examine the association between skinfold thickness in another region—the abdominal region—and risk of Alzheimer’s disease are currently under way.
NR
—Karen L. Spittler
Suggested Reading
Whitmer RA, Gunderson EP, Barrett-Connor E, et al. Obesity in middle age and future risk of dementia: a 27 year longitudinal population based study. BMJ. 2005;330:1360-1364.
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