Weight loss often precedes onset of dementia

New research suggests that it is common for patients with Alzheimer's or vascular dementia to lose a few pounds in weight in the years before their condition is diagnosed, US investigators report.

They say further studies are needed to determine why this occurs, and whether nutritional interventions would have any impact.

Previous studies have looked at the link between weight loss and dementia, but most have not been able to answer the question of which comes first.

The present, forward-looking study has "to my knowledge, the longest follow-up period of any (similar) study to date," Dr. Lenore J. Launer, from the National Institutes of Health in Bethesda, Maryland, told AMN Health.

The results, which appear in the January issue of the Archives of Neurology, are based on analysis of data from 1890 men who participated in the Honolulu-Asia Aging Study, a 32-year, population-based study of Japanese American men.

As part of the study, the subjects were weighted six times between 1965 and 1999 and were screened for dementia three times between 1991 and 1999.

At the last examination, the average age of the participants was 83 years, and 112 men had been diagnosed with dementia.

During the first 26 years of follow-up, no differences in original weight or weight change were seen between subjects who did or did not develop dementia. In the last 6 years, however, weight loss was greater in the group that developed dementia.

During this most recent period, the average weight loss for non-demented participants was 0.48 pounds per year, while those who became demented lost 0.79 pounds per year more than this.

To explain the link between weight loss and dementia, Launer commented that "as dementia is developing, it is possible that chemicals in the brain are changing so that a person's appetite is decreased or their metabolism is altered."

Dr. Michael Grundman, from Elan Pharmaceuticals in San Diego, notes in a related editorial that genetic factors play a large part in Alzheimer's disease, so "it may be too optimistic to suppose that nutritional approaches will necessarily have a huge impact on preventing Alzheimer's disease or slowing cognitive decline."

Nevertheless, he says, "even modest effects could have large public health implications."

SOURCE: Archives of Neurology, January 2005.