Physical activity doesn't improve cognition in older adults, but it may maintain it

An old proverb states, “When brains are needed, brawn won’t help.” That’s the basic conclusion from a trial that tested whether a 2-year physical activity program could improve cognitive function or prevent cognitive impairment, compared with a health education program, in sedentary older adults.

The investigators found that the physical activity program didn’t improve either overall or specific cognitive function, compared with a health education program. Cognitive function remained stable over 2 years for all participants, according to the study published August 25, 2015 in JAMA.

But this doesn’t mean that physical activity offers no benefit for sedentary older adults.

Researchers at Wake Forest School of Medicine, in Winston-Salem, NC, undertook the study because epidemiological evidence has supported the benefits of physical activity in lowering rates of cognitive decline. Also, exercise is associated with improved cerebral blood flow and neuronal connectivity, and maintenance and perhaps improvement in brain volume. Even in transgenic Alzheimer mouse models, exercise reduced beta-amyloid deposition. Yet, evidence from randomized trials in humans has been limited and mixed.

Thus, this randomized clinical trial, the Lifestyle Interventions and Independence for Elders (LIFE) study, enrolled 1,635 sedentary adults aged 70 to 89 years at 8 US centers from February 2010 until December 2011. The researchers randomized participants to either a structured, moderate-intensity physical activity program (walking, resistance training, and flexibility exercises) or a health education program of educational workshops and upper-extremity stretching. Researchers measured cognitive function and incidence of mild cognitive impairment (MCI) or dementia at the beginning of the study and again at 24 months.

The researchers found that cognition measures among participants in the physical activity program were no better than those in the health education program. There was also no significant difference between groups in the incidence of MCI or dementia (13.2% in the physical activity group vs 12.1% in the health education group).

Lead author Kaycee M. Sink, MD, MAS, Medical Director of the Kulynych Memory Assessment Clinic at Wake Forest, took a positive view of these results. “Both groups preserved their cognitive function over the course of 2 years. They stayed the same, which is really remarkable because we would have expected older adults in this age range to have declined at least some over 2 years,” she said in a JAMA interview. “Older adults should stay active physically, cognitively, and socially. All of those things are important to maintaining independence and cognitive function as you age.”

Another positive finding: Participants in the physical activity group who were 80 years old or older and those with poorer baseline physical performance had better performance in executive function tasks compared with those in the health education group.

“This finding is important because executive function is the most sensitive cognitive domain to exercise interventions, and preserving it is required for independence in instrumental activities of daily living,” the authors wrote. “Future physical activity interventions, particularly in vulnerable older adult groups…may be warranted.”