Acute Exercise Alters Brain Activation In Older Adults: What Is The Role Of Sleep?

Abstract

Insufficient sleep is associated with altered brain activation and poor cognitive performance. Aerobic exercise training enhances neural efficiency and improves cognition. PURPOSE: To examine sleep’s role in the effect of acute aerobic exercise on brain functional activation and cognitive performance. METHODS: We studied healthy, physically active older adults (n = 31; mean age = 66.2 ± 7.4 years (range = 55-81); 74.2% women; 93.6% > high school education; body mass index = 25.7 ± 4.2). During two counterbalanced study visits, participants engaged in 30 minutes of moderate-intensity bicycle exercise or seated rest, followed by a functional MRI scan. While in the scanner, participants completed the Erikson Flanker Task. Prior to the first study visit they also completed 7.9 ± 3.3 nights of wrist actigraphy. Actigraphic sleep indices included total sleep time (TST), sleep efficiency (SE), wake after sleep onset (WASO), and average wake bout length (WBL). RESULTS: Compared to rest, acute exercise significantly increased functional activation in the right superior parietal lobule (SPL; beta = 0.14, p = 0.011) and decreased activation in the left anterior cingulate cortex (ACC; beta = -0.09, p = 0.012). After adjustment for age, sex, race, and education, greater WASO was associated with less exercise-induced change in SPL activation (beta = -0.05, p = 0.001). There were no significant associations between TST, SE, or WBL and exercise-induced changes in functional activation. Acute exercise did not significantly affect Flanker Task performance. CONCLUSIONS: Acute moderate-intensity exercise alters functional activation in brain regions involved in executive function and inhibitory control, which align with previous exercise studies showing a conflict-related shift from ACC to SPL activity. Our findings suggest that the short-term effects of acute exercise may accumulate and promote the cognitive improvements linked to exercise training. Moreover, our findings suggest that greater time awake after initial sleep onset (i.e., sleep fragmentation) may attenuate the benefits of aerobic exercise on functional activation in the aging brain. Randomized controlled trials are necessary to further evaluate the interactive effects of sleep and acute exercise in older adults.