Mid-Life Obesity Linked to Old-Age Dementia
Study links higher weight to higher risk of cognitive decline later
THURSDAY, April 28, 2005 (HealthDay News) -- Excess poundage in midlife could spell cognitive trouble in your golden years, claims a large new study that links obesity to dementia.
The findings, which confirm previous research, suggest that "being fat has a detrimental impact on the brain," said study co-author Rachel A. Whitmer, a research scientist at the Division of Research, Kaiser Permanente Northern California.
It's still unclear, however, how putting on extra pounds leads people to lose their mental faculties.
The findings appear in the April 28 online issue of the British Medical Journal.
Whitmer and her colleagues studied the medical records of 10,276 people who were members of the Kaiser Permanente health plan in Northern California from 1964 to 1973. All were between 40 and 45 years old. The researchers followed up on the plan members by examining their records from 1994.
By 1994, doctors had diagnosed dementia -- the decline of cognitive functioning -- in 713, or 7 percent, of the patients.
People who were obese in middle age -- with a body-mass index of 30 or above -- were 74 percent more likely to have dementia than those of healthy weights, while overweight people, with body mass indexes of 25 to 29.9, were 35 percent more likely to have dementia. The effect was more significant in women.
Body-mass index is a ratio of weight to height.
Men and women who were judged to be fattest by a skin-fold measurement -- in which calipers are used to gauge body fat -- were 60 percent to 70 percent more likely to have dementia than those who had the lowest fat levels.
The researchers took into account other factors such as cardiovascular health and diabetes to make sure they had a pure link between obesity and dementia. "We adjusted for everything under the sun we could think of that could possibly explain the size of this effect," Whitmer said.
However, she acknowledged that the researchers didn't examine the physical activity of the subjects, making it unclear if lack of exercise could contribute to development of dementia.
William Thies, vice president for medical and scientific affairs with the Alzheimer's Association, said he was impressed by the size of the study. The findings are "another good reason to be careful about how big you get. It's clearly another message saying this (obesity) is not a good thing."
But there's only speculation about why obesity leads to dementia, Thies added. One theory is that high-fat diets may damage the brain, he said. According to Whitmer, it's also possible that obesity could lead to inflammation, causing problems in the brain.
What to do? Whitmer said the findings are actually good news because they suggest that one of the risk factors for dementia is controllable.
"It's certainly hard, but people can make lifestyle changes and lower their weight," she said. "This shows that if you lose weight, it has good effects, and it means there are beneficial effects further down the line."
To learn more about proper weight loss, visit the National Women's Health Information Center.