Studies in recent years confirm that weight loss precedes the onset of Alzheimers disease. Now, researchers at Washington University in St. Louis say the rate of weight loss doubles in the year preceding clinical symptoms. David Johnson, with the university medical school and Alzheimers Disease Research Center, is lead author of the study. "What we noticed," he says "was that when they were healthy, on average most people were losing about half a pound [.23 kilos] a year, but then as they got closer to the onset of clinical symptoms, it went from about a half a pound [.23 kilos] to just a little over a pound a year [.45 kilos]."
Johnson says while age-related weight loss is considered normal, accelerated loss is a clue to the progression of the disease. "We think that there is something about a metabolic change that is occurring. And, [we hope to] look into that metabolic change with further research."
Johnson says the study factored out other conditions that can lead to weight loss, like depression, hypertension, and history of heart disease or stroke. "In other words, no matter what we did to control for extraneous medical factors, none of them impacted the strong relationship between weight loss and the onset of Alzheimers disease.
Washington University researchers followed 499 older men and women, all of whom were cognitively healthy at the beginning of the study. Among them 125 went on to develop dementia. Johnson says those people weighed on average 3.6 kilos less at the start of the study than those who did not develop dementia. "That suggests that the Alzheimers disease has been at play for a number of years, maybe as long as a decade or more, and this is impacting people's weight over the long run."
Johnson says more research of this pre-clinical stage of Alzheimers may yield answers for slowing down or preventing the disease. The study is published in the September issue of Archives of Neurology.