Physical activity has been linked to improved cerebral blood flow and neuronal connectivity as well as maintenance or improvement in brain volume, but there is little evidence is available to support whether exercise actually lowers the rate of cognitive decline. A new study published in JAMA examines the effect of physical activity on cognitive function.

Kaycee M. Sink, MD, MAS, of the Wake Forest School of Medicine, Winston-Salem, NC, and colleagues evaluated whether a 24-month physical activity program would result in better cognitive function, lower risk of mild cognitive impairment (MCI) or dementia, or both, compared with a health education program. Participants were sedentary adults who were at risk for mobility disability but able to walk about a quarter mile and were between the ages of 70–89 years. Subjects were randomized to either a structured, moderate-intensity physical activity program (walking, resistance training, flexibility exercises) or a health education program (educational workshops, upper-extremity stretching). Measures of cognitive function and incident MCI or dementia were determined at 24 months.

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Compared with the health education program, the moderate-intensity physical activity intervention did not result in improved global or domain-specific cognition. There was also no significant difference between the physical activity group and the health education program group in the incidence of MCI or dementia (13.2% vs. 12.1%, respectively), although this outcome had limited statistical power. Subjects in the physical activity group who were ≥80 years and those with poorer baseline physical performance had better changes in executive function composite scores 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. Future physical activity interventions, particularly in vulnerable older adult groups (e.g., ≥80yrs of age and those with especially diminished physical functioning levels), may be warranted,” the authors conclude.

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