October 24, 2006
Carrying excess pounds during the middle years may do more than just make it hard to fasten your belt. It also bodes poorly for thinking and memory, French researchers report. The findings add to a growing body of evidence that being fat during the middle years may be bad for the brain.
In the study, middle-aged adults with a high Body Mass Index (BMI) received lower scores on cognitive tests than middle-aged adults with low BMI. Body Mass Index, or BMI, is a mathematical formula based on height and weight that doctors use to assess obesity. [The National Institutes of Health has a handy BMI calculator on the Web.] 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. Findings appeared in Neurology, the scientific journal of the American Academy of Neurology.
The study investigated the relationships between BMI and cognitive function in 2,223 healthy men and women in France through the use of four tests measuring thinking and memory. The participants, who were between the ages of 32 and 62, were initially tested in 1996 and again five years later.
The study found that a higher BMI was associated with lower cognitive test scores. Results from a test involving word memory recall show that people with a BMI of 20 remembered an average of 9 out of 16 words, while people with a BMI of 30 remembered an average of 7 out of 16 words.
"A higher BMI in 1996 was also associated with a higher cognitive decline at follow-up in 2001," said study author Maxime Cournot, M.D., of the Toulouse University Hospital and the National Institute of Health and Medical Research in Toulouse, France.
She notes that obese people often have hardening of the arteries, or "atherosclerosis," a condition that impairs blood flow. Damage to blood vessels in the brain could hamper that vital organ and impair memory and thinking. Overweight individuals are also prone to diabetes and problems with insulin control, the hormone that regulates blood sugar. Diabetes, like heart disease, has also been linked to Alzheimer's and memory problems.
Scientists also speculate that fat cells may produce harmful chemicals that promote inflammation in blood vessels throughout the body, including in the brain. People who are overweight may also tend to have diets low in "good" fats, such as those found in fish.
The findings add to a growing body of scientific evidence that being overweight in your middle years may contribute to Alzheimer's in old age.
Last year, researchers from Sweden came to a conclusion when they found that men and women who are obese at midlife have an increased risk for Alzheimer's disease as they age. [See the article, "Obesity at Midlife May Raise Your Alzheimer's Risk."]
Though excess weight is emerging as an important risk factor for Alzheimer's, age remains the most important factor: 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 and other studies suggest, keeping your weight down in your middle years and beyond may help you to remain mentally alert as well. With more and more Americans both young and old becoming obese, it is vital that people maintain healthy lifestyles to help maintain the brain.
For more information on risk factors for Alzheimer's and keeping the mind sharp into old age, visit www.ALZinfo.org, the Alzheimer's information site.
M. Cournot, J.C. Marquie, D. Ansiau, C. Martinaud, H. Fonds, J. Ferrieres, and J.B. Ruidavets: "Relation between body mass index and cognitive function in healthy middle-aged men and women." Neurology, Volume 67: October 10, 2006, page 1208.