Losing weight late in life may indicate that the brain is inching toward dementia (search). A long-term study shows that elderly men with dementia lost nearly 10 percent of their body weight a few years before their dementia diagnosis.

The report appears in the January issue of Archives of Neurology.

Shedding pounds is common among the elderly. It’s often the result of disease, and the consequences can be serious. If nutrition and energy suffer, health can decline.

Dementia may come on the heels of late-life weight loss, say Robert Stewart, MD, and colleagues. Stewart works with London’s Institute of Psychiatry. Their report appears in the January issue of Archives of Neurology,

Stewart’s team studied more than 1,800 Japanese-American men, following them for 32 years. Participants were examined six times from 1965-1999. They weighed in at each visit and were also screened for dementia at their last three appointments.

The men were pretty lean to begin with. In middle age, their average body mass index (BMI) was 24. That’s a normal BMI, which indicates normal amounts of body fat.

Nothing remarkable happened during the study’s first 26 years. During that time, the men were moving from middle age to senior status. No weight-related differences stood out then between the men who were later diagnosed with dementia and those who weren’t.

Time changed that. When the men were elderly (aged 77-88), the link between weight loss and dementia emerged.

Dementia was eventually diagnosed in 112 men. Over the last six years of the study, they had lost a little less than one extra pound per year than those without dementia.

That might not sound like much. But over time, it added up to a loss of at least 11 pounds for the men with dementia. That’s about 10% of their body weight, say the researchers, noting that the men never had much weight to spare.

In many cases, the weight loss preceded the dementia diagnosis by two to four years. That could mean that weight loss is an early warning sign of future dementia.

Once dementia sets in, it can make matters worse. Patients may forget to eat, making them suffer nutritionally. As a result, they can have a harder time healing from wounds or falls, becoming more physically dependent.

“Weight change and nutritional status should be taken seriously at least from the time of diagnosis if not at earlier stages of more mild cognitive impairment,” say the researchers.

It’s too soon to know if avoiding weight loss could help prevent or slow dementia, says Michael Grundman, MD, MPH, in an accompanying editorial.

“It may be too optimistic to suppose that nutritional approaches will necessarily have a huge impact,” writes Grundman, an Alzheimer’s disease specialist with Elan Pharmaceuticals. “Nevertheless, even modest effects could have large public health implications.”

More work is needed on the topic, he concludes.

By Miranda Hitti, reviewed by Brunilda Nazario

SOURCES: Stewart, R. Archives of Neurology, January 2005; vol 62: pp 55-60. Grundman, M. Archives of Neurology, January 2005; vol 62: pp 20-22. News release, JAMA-Archives.