Study finds a connection, but researchers aren't sure why
MONDAY, Aug. 20 (HealthDay News) -- Women who develop dementia lose weight a decade or more before major symptoms appear, a new study suggests.
The weight loss is small among individual women and can't be used to diagnose who will go on to become senile. Still, the research does point to a long incubation time for dementia, said study author Dr. David Knopman, a professor of neurology at the Mayo Clinic College of Medicine, in Rochester, Minn.
"It's a demonstration of the gradual and insidious nature" of dementia, Knopman said. Some aspects of the condition "can be present to a minor degree two decades before the memory problems."
The findings are published in the Aug. 21 issue of Neurology.
Knopman and his colleagues examined a database of 481 men and women in Rochester, Minn., who were diagnosed with dementia between 1990 and 1994. Then the researchers looked into medical records going back decades to check the weights of the study participants. They also checked the records of a similar group of people who did not develop dementia.
The researchers found the weights of the men had nothing to do with whether they developed dementia. For women, weight loss 21 to 30 years before a diagnosis of dementia was irrelevant, but those who lost weight more recently were more likely to develop cognitive problems.
"Women destined to become demented as a group became lighter and weighed less than those who weren't destined to get dementia," Knopman said. "It's only a matter of a few pounds, but, on average, they were a bit lower."
By the time the women were diagnosed with dementia, they weighed an average of 12 pounds less than women who didn't develop cognitive problems.
The connection between weight loss and dementia isn't new. According to Knopman, other researchers have found evidence of it over the past five to 10 years. But the new study is unusual because it found weight loss so many years before a dementia diagnosis, he said.
No one knows why women who develop dementia lose weight years earlier but men don't. Knopman theorized that it may have something to do with both social and biological factors.
Older women may eat less in general, because many live alone as widows, and the approaching dementia may cause a decreased sense of taste and smell that makes eating less appealing, he said.
Another theory is that dementia in its earlier stages affects the way the body processes blood sugar, said Dr. Lon Schneider, a professor of psychiatry, neurology and gerontology at the University of Southern California.
He was hesitant to speculate why women and men might be affected differently. However, he did say the findings could eventually lead to earlier diagnosis of dementia.
According to Schneider, the earliest signs of cognitive problems occur about three years before dementia fully sets in.
What's the next step? "To try to understand why this [weight loss] happens and develop preventive treatments for Alzheimer's disease," Knopman said. "That's the key issue."
Learn more about Alzheimer's disease from the Alzheimer's Association.
SOURCES: David Knopman, M.D., professor, neurology, Mayo Clinic College of Medicine, Rochester, Minn.; Lon Schneider, M.D., professor, psychiatry, neurology and gerontology, University of Southern California, Los Angeles; Aug. 21, 2007, Neurology