September 20, 2006
Many men and women tend to drop some pounds as they hit their 70s, 80s, and beyond. But the slow and steady weight loss of aging may speed up prior to the onset of Alzheimer's disease, a new study shows. The findings were published in the Archives of Neurology, a scientific journal from the American Medical Association.
Researchers at the Washington University School of Medicine, in St. Louis, Missouri, examined 449 healthy seniors, aged 65 to 95. None had any memory problems or signs of Alzheimer's disease at the start of the study. During the next six years, they were given annual medical check-ups and assessed for any medical changes, including weight loss or memory problems.
Over the course of the study, 125 participants developed Alzheimer's disease. Those who did weighed about eight pounds less at the beginning of the study than those who did not develop Alzheimer's disease. In addition, weight loss sped up in the period before Alzheimer's was diagnosed.
Healthy seniors who did not develop Alzheimer's disease lost, on average, about 0.6 pounds per year. Those who developed Alzheimer's, in contrast, lost about twice that, or 1.2 pounds, in the year before the first symptoms of Alzheimer's appeared. The acceleration in weight loss occurred even when the researchers considered other factors that may contribute to weight loss, including age or medical conditions such as high blood pressure or strokes.
The findings are consistent with earlier studies, including one published early this year that found that unexpected weight loss may develop several years before the memory begins to fade, and well before most cases of Alzheimer's are even diagnosed. Still, it is important to emphasize that many elderly people who lose weight do not go on to develop Alzheimer's disease.
Weight Loss and Old Age
Changes of old age, such as reduced appetite, poor mobility, general frailty, and diminishing height, causes many otherwise healthy seniors to lose weight. Men and women with Alzheimer's disease also tend to be thinner than those without the illness. Poor appetite, disorientation, problems with visions and perception, and an inability to feed oneself can all contribute to poor nutrition in those with the disease. During the late stages of Alzheimer's, people commonly lose up to two pounds a year. Those who lose the most weight are more likely to do worse and to be placed in a nursing home.
This study showed that rapid weight loss may occur very early on, before memory problems or other symptoms even arise. Doctors are uncertain why this may happen. Some have suggested that individuals with Alzheimer's forget to eat. However, this is unlikely given that weight loss often precedes the onset of memory problems and other symptoms of dementia. Depression has also been suggested as a possible cause of early weight loss, and indeed, participants with Alzheimer's in this study tended to be more depressed than others. However, depressed patients did not show any changes in body weight compared with those who were not depressed.
"There are reports of mild to moderate changes in taste and smell in healthy aging populations and in populations with dementia, and these factors need to be measured rigorously in future studies," the authors write. "Subtle gustatory changes could result in cumulative decreases in caloric intake or decreases in the quality of food consumed by individuals with dementia of the Alzheimer's type."
Experts advise that any changes in weight or nutritional status should be carefully monitored and assessed in the elderly. Weight changes may have serious consequences for those suffering from Alzheimer's disease. Poor nutrition and frailty, for example, often lead to falls (and consequent broken bones), slow healing of wounds, and increased physical dependence during the later stages of the illness.
The symptoms of Alzheimer's disease, even during its early stages, may be made worse when an individual does not receive adequate nourishment. In addition to careful monitoring, some simple caregiving measures may help. For example, researchers report that using brightly colored tableware may make it easier for those with advanced Alzheimer's disease to see the food and beverages in front of them, leading them to eat and drink more at mealtimes.
David K. Johnson, Ph.D.; Consuelo H. Wilkings, M.D.; John C. Morris, M.D.: "Accelerated Weight Loss May Precede Diagnosis in Alzheimer's Disease." Archives of Neurology, Volume 63, September 2006, pages 1312-1317.