Social Activity in Late Life Associated with Better Motor Function

Susan Jeffrey

June 30, 2009

June 30, 2009 — A new analysis from the Rush Memory and Aging Project finds that people who report less frequent participation in social activities have a more rapid rate of motor decline in old age.

"We found that the rate of motor decline you get with 1 point on the social-activity scale is equivalent to being 5 years older at baseline," Aron S. Buchman, MD, from the Rush Alzheimer's Disease Center and department of neurological sciences at Rush University Medical Center, in Chicago, Illinois, told Medscape Neurology. "The differences in rate of decline we're talking about are not trivial."

Their findings suggest that not only physical activity but cognitive activity and now social activity are all part of an overall approach to maintaining good health into older age, Dr. Buchman said. "It gives impetus to a multidisciplinary approach from a public-health point of view, because it's certainly a lot cheaper to facilitate social activity than it is to be handing out medication."

Their results are published in the June 22 issue of Archives of Internal Medicine.

Motor Decline

Loss of motor function occurs commonly in aging, the authors write, but little is known about the factors that predict this idiopathic motor decline. Studies by their group and others have shown that physical activity slows the rate of motor decline in community-dwelling elders, they note, but accumulating evidence suggests a broader range of activities, including social activity, are associated with health benefits such as longevity, risk for dementia, and the rate of cognitive decline.

The Rush Memory and Aging Project is a longitudinal cohort study of people living in the community in Chicago who have agreed to be examined annually and to donate brain and spinal cord upon their death. The study began in 1997, and eligible subjects were free of Parkinson's disease, stroke, or dementia at baseline.

For this analysis, 906 people were followed for a mean of 4.9 years. Participants self-rated the frequency of their current participation in social activities in 6 domains at baseline, from which a summary measure of social activity was calculated. Social activities included going to restaurants, sporting events, playing bingo, taking day or overnight trips, doing community volunteer work, or attending church or religious services. For each of these types of activities, they rated their involvement on a scale from 1, which would be once a year, to 5, which would be every day, Dr. Buchman explained.

The main outcome measure was the annual change in a composite measure of global motor function based on 9 measures of muscle strength and 9 motor performances recorded at their annual assessment.

More Rapid Decline

The mean social activity score for the cohort was 2.6 (standard deviation, 0.58), ranging from 1.00 to 4.17, with higher scores indicating more frequent social activity. Social activity was inversely associated with age, positively associated with higher education, and more frequent among women than men.

After controlling for age, sex and education, they found that global motor function declined by about 0.05 units per year on average, and each 1-point decrease in social activity was associated with a 33% more rapid decline in motor function.

The effect of each 1-point decrease in social activity score at baseline was approximately equivalent to being 5 years older at baseline (P < .001), the researchers note.

"Furthermore, this amount of motor decline per year was associated with a more-than-40% increased risk of death and a 65% increased risk of incident Katz disability," they write.

Risk for Adverse Outcome With Each 1-Point Decrease in Baseline Social Activity Scale

End Point Hazard Ratio 95% CI
Mortality 1.44 1.30 – 1.60
Incident Katz disability 1.65 1.48 – 1.83

The association between social activity and global motor decline was not altered after adjustment for confounding factors, including late-life physical and cognitive activity, disability, global cognition, depressive symptoms, body composition, or other chronic medical conditions.

Dr. Buchman cautioned that this is an observational study and will require replication in other cohorts. However, he added, "the fact that we've found this means that we need additional research to figure out what the biology is and to be clearer about what it is about social activity that's driving this association to be able to use it from a public-health point of view." Some activities may have more positive effects on motor function than others.

Increasing work looking at mirror neurons, for example, may provide an anatomical substrate where social activity and motor function may affect the same neurons, he added.

As the Rush study continues and more brains are donated, Dr. Buchman concluded, "We're beginning to look morphologically, histochemically, and genetically at these brains to see if we can link structural and biological changes to the clinical findings that we have while they're living."

The study is supported by grants from the National Institute on Aging, the Illinois Department of Public Health, and the Robert C. Borwell Endowment Fund. The authors report no disclosures.

Arch Intern Med. 2009;169:1139-1146. Abstract