WASHINGTON (Reuters) - Some older people who inexplicably lose weight may be in the early stages of Alzheimer's disease, U.S. researchers reported on Tuesday.
A study of more than 800 healthy nuns, priests and monks who were slightly overweight on average showed that those who lost about one unit of body mass index a year -- a little more than five pounds (2 kg) or so -- had a 35 percent greater risk of developing Alzheimer's than those with no weight change.
Those who gained no weight had a 20 percent greater risk of developing the disease than people who gained a pound (half a kg) or so a year.
The findings held true even after considering factors such as chronic health problems, age, sex, and education.
Writing in the journal Neurology, Dr. Aron Buchman and colleagues at Rush University Medical Center in Chicago said they used information from an ongoing study of Catholic volunteers who undergo extensive health exams and who keep careful diaries.
When the study began, none of them had dementia, and their average body mass index, a measure of height and weight, was 27.4, just over the 25 cutoff for being overweight.
During the study, 151 of the men and women, or 18.4 percent, developed Alzheimer's.
"These findings suggest that subtle, unexplained body mass and weight loss in an older person may be an early sign of AD and can precede the development of obvious memory problems," said Dr. David Bennett, who directs the Rush Alzheimer's Disease Center.
"The most likely explanation is that there is something about these individuals or about this disease that affects BMI before the clinical syndrome becomes apparent -- that loss of BMI reflects the disease process itself."
Doctors can look at a patient's weight when trying to determine their risk of dementia, the researchers said.
"There are actually very few predictors of Alzheimer's disease," Bennett said. "This study makes us think about the spectrum of clinical signs of AD beyond changes in memory and behavior and motor skills. Changes in BMI are easy to measure in a doctor's office without an expensive scan."