December 7, 2009
Older adults who maintain their muscle strength are at lower risk of memory problems and Alzheimer's disease than those who are weaker, a new study shows. The findings appeared in the Archives of Neurology, a journal from the American Medical Association.
Doctors at Rush University Medical Center in Chicago found that the greater a person's muscle strength, the less likely they were to be diagnosed with Alzheimer's disease. Those who were stronger were also less likely to have mild cognitive impairment, a form of memory loss that, while not as severe as Alzheimer's, sometimes precedes the disease.
Alzheimer's is perhaps best known as a disease that robs the memory, but the disease wreaks havoc with many aspects of the mind and body. People with Alzheimer's often become depressed, and they can also have problems with walking and eating. Recent studies suggest that weight loss and other non-mental problems may be early harbingers of the diseases, in some cases occurring years before the onset of serious memory loss.
In the current study, part of the ongoing Rush Memory and Aging Project, the researchers studied more than 900 elderly men and women living in various neighborhoods of Chicago. None had Alzheimer's or serious memory problems at the start of the study. All were tested for muscle strength in the arms and legs and other muscle groups. They were also tested for memory loss and other cognitive problems.
After four years, the researchers diagnosed Alzheimer's in 138 of the seniors. They found that those adults who were the weakest at the start of the study were most likely to be diagnosed with Alzheimer's or mild cognitive impairment. They also tended to be older, but when the investigators factored in such variables as age and genetic factors, robust muscle strength was associated with protection against Alzheimer's.
Those men and women who ranked in the top 10 percent of muscle strength appeared to be about 60 percent less likely to develop Alzheimer's than those in the bottom 10 percent of strength. The strongest seniors had some memory loss, but the rate of decline tended to be slower than those who were weakest.
An additional 275 seniors showed signs of memory problems. Again, the strongest adults were half as likely to be diagnosed with mild cognitive impairment as the weakest.
Aging can bring many changes, including frailty and falls, that can compromise mental and physical well-being. Other studies have shown that regular physical activity, like walking or ballroom dancing, may help protect against Alzheimer's. Regular exercise can likewise build muscles and help to maintain strength, this study suggests, and may also be good for the mind.
Patricia A. Boyle, Ph.D., Aron S. Buchman, M.D., Robert S. Wilson, Ph.D., et al: "Association of Muscle Strength With the Risk of Alzheimer's Disease and the Rate of Cognitive Decline in Community-Dwelling Older Patients." Archives of Neurology, Vol. 66, No. 11, pages 1339-1344.