Physical Activity Level Affects Rate of Cognitive Decline
Declines in processing sleep and episodic memory were observed in those with low levels of activity.
Lower levels of physical activity in a diverse cohort of older individuals have been linked to greater cognitive decline, according to study results published in Neurology.
“The number of people over the age of 65 in the United States is on the rise, meaning the public health burden of thinking and memory problems will likely grow. Our study showed that for older people, getting regular exercise may be protective, helping them keep their cognitive abilities longer,” study coauthor Clinton Wright, MD, MS, said in a statement.
While previous research has tied cognitive performance to leisure-time physical activity (LTPA), a Cochrane review found the evidence to be insufficient. Previous studies also failed to use comprehensive cognitive measures or assess changes over time.
To assess LTPA's role in protecting against cognitive decline, Joshua Willey, MD, of the Department of Neurology at Columbia University in New York, and colleagues analyzed data from the Northern Manhattan Study MRI substudy. Participants were assessed for LTPA via questionnaire and cognition was assessed with a standard neuropsychological examination (NPE) at baseline and 5 years.
The diverse cohort included 1228 participants with a mean age of 71 years. Ten percent of the cohort reported moderate to heavy physical activity. After adjusting for education, sex, age, and insurance status, participants who reported no to light LTPA performed lower in all cognitive domains except episodic memory compared to participants who reported moderate to heavy LTPA. When excluding patients who hadcognitive impairment at baseline, the results were similar but not significant when adjusted for MRI and vascular factors.
When assessed change in cognitive performance over time, researchers found that participants who reported no to light LTPA had greater declines in processing speed than those who reported moderate to heavy LTPA after adjusting for sociodemographics and vascular factors (β -0.254, P=.023 and β -0.231, P=.040). Although not significant, there was a similar decline in episodic memory. Further, when exercise groups were analyzed separately, participants who reported moderate to heavy LTPA demonstrated higher initial scores and a slower decline in cognitive assessments.
Finally, after excluding those with baseline cognitive impairment, participants who reported no to light LTPA had significant declines in processing speed (β -0.243, P= .037) and episodic memory (β -0.231, P= .046) over time. This association remained significant for episodic memory after adjusting for vascular and MRI factors (P= .027 for both).
“In this racially/ethnically diverse cohort of older adults, we found that, compared to moderate–heavy LTPA, no or low leisure-time physical activity was associated with a greater decline in processing speed among all participants, and episodic memory among those unimpaired at baseline,” the authors wrote. “The degree of decline was equivalent to the expected decline associated with approximately 10 years of cognitive aging.”
“Physical activity is an attractive option to reduce the burden of cognitive impairment in public health because it is low cost and doesn't interfere with medications,” Dr. Wright said. “Our results suggest that moderate to intense exercise may help older people delay aging of the brain, but more research from randomized clinical trials comparing exercise programs to more sedentary activity is needed to confirm these results.”
The study was funded by the National Institute of Neurological Disorders and Stroke. The authors report no disclosures.
Willey JZ, Gardener H, Caunca MR, et al. Leisure-time physical activity associates with cognitive decline: The Northern Manhattan Study. Neurology. 2016; doi: 10.1212/WNL.0000000000002582.