Twice-Weekly Workout in Middle Age Cuts Alzheimer’s Risk
Working out in middle age helps keep the brain flexible in old age.
So say researchers here who found that people who were physically active at least twice a week during mid-life cut their risk of dementia by more than 50% and the risk of Alzheimer’s disease by more than 60%, irrespective of other risk factors.
In a population-based cohort study, Miia Kivipelto, M.D., Ph.D. and colleagues of the Aging Research Center at the Karolinska Institute randomly selected 1,449 participants who were surveyed and examined at midlife.
They participated in a re-examination in 1998 at ages 65 to 79.
Surveys included self-administered questionnaires on health behavior, health status, and medical history, the investigators reported in an online edition of The Lancet Neurology. Examinations included measurement of blood pressure, height, and weight. Body mass index was calculated and serum cholesterol was measured. The examination also included assessment for movement disorders.
Two hundred and one participants said they exercised daily in middle age, 580 said they worked out two to three times a week, 421 once a week, 250 two to three times a month, 404 a few times a year, and 79 said they were never exercised.
Alzheimer’s disease (AD), one form of dementia, is a progressive, degenerative brain disease. It impairs memory, thinking, and behavior.
Memory impairment is a necessary feature for the diagnosis of this or any type of dementia. Change in one of the following areas must also be present: language, decision-making ability, judgment, attention, and other areas of mental function and personality.
The rate of progression is different for each person. If AD develops rapidly, it is likely to continue to progress rapidly. If it has been slow to progress, it will likely continue on a slow course.
Re-examination included assessment for APO-E genotype to identify genetic risk, and cognitive status was assessed by mini-mental status examination. Based on results of the mini-mental status exam, 294 were referred for complete neurological and cardiovascular examination.
At the 1998 re-examination 117 participants had evidence of dementia and 76 received a clinical diagnosis of Alzheimer’s disease.
Participants who exercised at least twice a week in midlife had an adjusted odds ratio of 0.48 for dementia (95% CI 0.25-0.91) and an adjusted OR of 0.38 for Alzheimer’s disease (95% CI 0.17-0.85) compared with those who exercised less. The importance of exercise remained even after adjusting for age, sex, education, follow-up time, locomotor disorders, APO-E genotype, vascular disorders, blood pressure, BMI, cholesterol, smoking, and alcohol use.
By causing both structural and chemical problems in the brain, AD appears to disconnect areas of the brain that normally work together.
About 10 percent of all people over 70 have significant memory problems and about half of those are due to AD. The number of people with AD doubles each decade past age 70. Having a close blood relative who developed AD increases your risk.
Moreover the benefit of exercise was even “more pronounced among APO-E _4 carriers,” the authors wrote. Among carriers exercise was associated with an odds ratio of 0.34 (95% CI 0.15-0.74) for Alzheimer’s disease.
The authors noted a number of limitations for their findings, notably survival bias. Those who exercised regularly tended to be older than those who didn’t exercise. Additionally, since only those who scored 24 or less on the mini-mental status exam were referred for complete neurological and cardiovascular evaluation some dementia cases may have been lost.
The authors concluded that the results “indicate that regular leisure-time physical activity may be protective against dementia and Alzheimer’s disease later in life.”
Revision date: June 14, 2011
Last revised: by Dave R. Roger, M.D.