Women's Health: Weight loss may signal future dementia

A new study suggests dementia in women is preceded by weight loss that begins years prior to diagnosis. Researchers say the weight loss may be a sign of subtle changes in the brain, such as decreasing motivation.

Dr. David Knopman and his colleagues at the Mayo Clinic in Rochester, Minn., studied the medical records of 481 people, three-quarters of them women, who had dementia, and 481 people of the same ages who had no history of dementia.

Between 11 and 20 years before the diagnosis of dementia, the weights of the two groups began to diverge, with the risk of dementia increasing as weight decreased. Ten years before diagnosis, women in the bottom half of the weight range were significantly more likely to develop dementia than those in the top half. During the year dementia was diagnosed, women in the bottom three-quarters of the weight range were all more likely to have dementia than those in the top quarter. This trend was not seen in the men.

The weight loss is thought to be due to loss of initiative and motivation associated with dementia, Knopman says. "Biologic changes going on in the brain that lead to dementing illness don't happen overnight, but in fact are evolving probably over decades before the memory problems actually become manifest."

The reason this difference showed up in women and not men may be social. Women in this age group are more likely to be preparing meals for themselves or their spouse. The men in this study population -- which was white, rural and midwestern -- were more likely to have a wife or an adult child cooking for them, so their own loss of motivation would have a smaller impact on their diet.