Weight Loss Comes Before a Cognitive Fall

ROCHESTER, Minn., Aug. 20 -- A decade before women develop dementia, they may begin to have an unexplained loss of weight, according to investigators here.

Women who went on to develop dementia weighed an average of 12 pounds less at the time of diagnosis than non-demented age-matched controls, reported David Knopman, M.D., of the Mayo Clinic, and colleagues, in a retrospective case-control study.

Weight loss did not predict dementia in men, however, the authors reported in the Aug. 21 issue of Neurology.

"One explanation for the weight loss is that, in the very early stages of dementia, people develop apathy, a loss of initiative, and also losses in the sense of smell," Dr. Knopman said. "When you can't smell your food, it won't have much taste, and you might be less inclined to eat it. And apathy and loss of initiative may make women less likely to prepare meals and more likely to skip meals."

In contrast, men are more likely to have their meals prepared for them, "which would lessen the effect of the apathy, loss of initiative and loss of sense of smell," Dr. Knopman added.

The authors identified patients who were diagnosed with dementia from 1990 through 1994, using records linked through the Rochester Epidemiology Project. They defined dementia according to Diagnostic and Statistical Manual of Mental Disorders, fourth edition (DSM-IV) criteria.

Each case was matched by gender and age to a patient from the same population. Controls were free of dementia in the year of dementia diagnosis of their matched cases. The weights of cases and controls were drawn from medical records.

The investigators identified a total of 481 patients who had been diagnosed with primary dementia of presumed vascular or degenerative origin during the study period and who had suitable matches. Information on weight for matched pairs was available for 295 female pairs and 76 male pairs.

The authors found that although there were no significant differences in weight between cases and controls from 21 to 30 years before the onset, women who developed dementia weighed significantly less than controls starting 11 to 20 years before the index year (the year of dementia onset), and that prior to the index year, and that this difference increased over time.

"We found a trend of increasing risk of dementia with decreasing weight in women both at the index year (test for linear trend, P