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