Background: Alzheimer's disease (AD) currently affects 5.4 million Americans and is the sixth leading cause of death in the United States. The mechanism of exercise-induced brain adaptations are not fully understood, but enhanced aerobic fitness has been postulated as an essential physiological mechanism and is beginning to be studied. The purpose of this analysis was to examine the relationship between changes in aerobic fitness and cognition following 6 months of aerobic exercise training in older adults with AD.
Methods: Twenty-seven community-dwelling older adults with mild to moderate AD completed a 6-month, 3 times per week, moderate-vigorous intensity cycling exercise program in 2 identical studies using a single-group repeated-measures designs. AD symptoms were measured with the AD Assessment Scale–cognitive subscale (ADAS-cog), while aerobic fitness was assessed by the intermittent shuttle walk test (ISWT) at baseline and 6 months. Pearson's correlation coefficient tests and linear regression were used to assess the relationship between changes in aerobic fitness and cognition.
Results: Adjusted for age, the 6-month change in ISWT distance had an inverse relationship with the 6-month change in ADAS-Cog (r = −0.49; P = .01), indicating that enhanced aerobic fitness was associated with improved cognitive changes. Linear regression was statistically significant when adjusted by age (F([2,14] =5.33, P =.01, R2 = .31).
Conclusion: Enhanced aerobic fitness may attenuate cognitive decline in persons with mild to moderate AD.
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