Longitudinal Association Between Low- And High-light Intensity Physical Activity And Cognitive Function In Older Adults

Abstract

PURPOSE: Regular moderate-to-vigorous intensity physical activity (MVPA) provides benefits for cognitive health among older adults. Recently, there has been a shift from focusing on MVPA to considering the potential benefits of light intensity PA (LPA), because older adults accumulate 3-4 hr/day of LPA. This study investigated the longitudinal association of objectively measured low-light intensity PA (LLPA) and high-light intensity PA (HLPA) with cognitive function in older adults. METHODS: Participants were recruited from the REasons for Geographic and Racial Differences in Stroke (REGARDS) Study. ActicalTM accelerometers provided estimates of LLPA (50-556 counts/min), HLPA (557-1,064 counts/min), MVPA (>1,065 counts/min), for 4-7 consecutive days. Incidence of cognitive impairment was defined by the Six-Item Screener. Letter fluency, animal fluency, word list learning and Montreal Cognitive Assessment (orientation and recall) were conducted to develop z-scores for domains of executive function and memory. Associations between LPA and cognitive impairment were examined using multivariate logistic regression models. General Linear regression models were used to assess the association between LPA and z-scores of executive function and memory. RESULTS: During 3.3 ± 0.5 years of follow-up, 4,941 participants (70.1 ± 8.6 yr, 54.2% women, 31.7% African American) were included, with 283 incident cases of cognitive impairment. Average time spent in LLPA and HLPA were 167.4±61.1, and 24.0±19.2 min/day, respectively. After adjustments for age, sex, race, education and other health related factors, participants in the highest HLPA quartile (40.9 min/day) had 35% lower risk of cognitive impairment than the lowest quartile (HR: 0.65, 95% C.I.: 0.45-0.94). Quartiles of HLPA were inversely associated with change over time in executive function and memory z-scores (P<0.01). CONCLUSION: Higher levels of objectively measured HLPA were independently associated with lower incidence of cognitive impairment, and better maintenance of memory and executive function in older adults. Future PA guidelines may need to be modified to include HLPA in addition to MVPA to sustain cognitive health in older adults.