"The most likely explanation is that there is something about these individuals or about this disease that affects body mass index (BMI) before the clinical syndrome becomes apparent - that loss of BMI reflects the disease process itself," study co-author Dr David A. Bennett, of the Alzheimer's Disease Centre at Rush University Medical Centre in Chicago, said in a prepared statement.

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The study included 820 people, 65 years and older, who were checked each year for an average of 6.6 years. At the start of the study, none of the volunteers had dementia and their average BMI was 27 (for reference, overweight begins at a BMI of 25 or above, while obesity starts at 30).

During the follow-up period, 151 of the volunteers (18.4 percent) developed Alzheimer's disease.

Decreasing BMI linked to increased risk
People who lost about one unit of BMI per year were at a 35 percent greater risk of developing Alzheimer's than those who had no change in BMI during the study, the researchers report. People who had no change in their BMI were at a 20 percent greater risk of developing Alzheimer's than those who gained six-tenths of a unit of BMI per year.

The researchers found a similar relationship between BMI changes and the rate of cognitive decline among the volunteers.

Exact links remain unclear
Exact links between unexplained weight loss and Alzheimer's remain unclear.

"Our understanding of Alzheimer's disease is changing as we get more information, particularly when we look at the pathology of the disease," said lead researcher Dr Aron Buchman, also at Rush. "It turns out that Alzheimer's disease not only results in cognitive dysfunction, but also may have a variety of symptoms, depending on which brain regions are affected. If the disease pathology affects a region of the brain that controls weight, your body mass may decline prior to loss of cognition."

The study appears in the September 27 issue of Neurology. – (HealthDayNews)

Visit our Alzheimer's Centre for more information.

September 2005
 

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