MONDAY, Jan. 10, 2005 (HealthDayNews) -- Weight loss, which has been previously associated with dementia and Alzheimer's disease, may begin up to six years before diagnosis, a new research suggests.

This is the first study to show that weight loss is associated with early cognitive impairment and that it increases as dementia worsens. The researchers said weight loss may contribute to, or speed up dementia, but it is not the primary cause of the condition.

The study was done among a group of Japanese-American men, and appears in the January issue of the Archives of Neurology.

"As a group, the men decrease in weight as they get older, but the men who got demented lost even more weight," said study co-author Lenore J. Launer, an investigator and chief of the Neuroepidemiology Section at the National Institute on Aging. "This suggests that when people are getting older, extra care needs to be given to make sure that they are getting an adequate diet," she added.

In their study, Launer and her colleagues collected data on 1,890 Japanese-American men, 77 to 98 years of age, who were part of the Honolulu-Asia Aging Study. Over 34 years, 112 of the men were diagnosed with dementia.

During the study, the men were examined six times. At the three most recent examinations, their weight was assessed and they were also tested for signs of dementia.

"Individuals who developed dementia had a significantly greater weight loss than individuals who did not develop dementia six years before the diagnosis," Launer said.

Many of the men with dementia had lost at least 11 pounds, which was about 10 percent of body weight among the men. This weight loss happened from two to six years before a clinical diagnosis of Alzheimer's or vascular dementia, the researchers noted.

Among men who did not develop dementia, only 12 percent had lost that much weight, the researchers found.

The increased weight loss among those with dementia may signal that something in the brain that controls appetite or metabolism is affected. "Weight loss is a sign of dementia," she said. "Not that it is leading to dementia."

Launer does not believe that weight loss causes Alzheimer's, or that maintaining weight can slow the process of increasing dementia. However, maintaining body weight may reduce the severity of other medical problems -- including falls, poor wound healing, and increased physical dependence -- that can accompany dementia, she said.

Launer added that she's not sure if these findings are applicable to other groups of men or women. "Further study is needed," she said.

Dr. Michael Grundman, head of the Alzheimer's Disease Prevention Program at Elan Pharmaceuticals in San Diego, said, "It is pretty clear that losing weight happens long before Alzheimer's is diagnosed."

"It [the research] suggests that people with mild cognitive impairment are already losing weight," he added.

According to Grundman, who wrote an accompanying editorial in the journal, weight loss could be a marker of impending dementia. "If doctors were to recognize this, then this is something they should think about in terms of cognitive decline or Alzheimer's disease," he said.

Weight loss may contribute to, or speed up dementia, Grundman said, "but it is not the primary cause of dementia." However, he suggested that maintaining body weight can help slow the progression of Alzheimer's.

"The weight loss that is associated with Alzheimer's is not normal," Grundman said. "There should be efforts to maintain body weight. Probably the earlier it is recognized that weight loss is occurring, the sooner you can intervene, and the potential benefits would be greater," he said. "It's not proven yet, but it just makes sense."

More information

The Alzheimer's Association can tell you more about dementia and Alzheimer's.

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