Associations of accelerometry-derived time in major activity intensities with cognitive outcomes: a compositional data analysis approach

BACKGROUND: Physical activity (PA), sedentary behavior (SB), and sleep are modifiable lifestyle factors linked to cognitive health. Prior research has largely relied on self-report to measure these constructs or ignored the compositional nature of these data. We applied compositional data analysis (CoDA) to quantify the association between accelerometry-derived measures of time in major activity domains and cognitive outcomes among older adults. METHODS: Participants were 927 older adults (Mage = 82.71 years, SD = 3.99, range = 76-95) from the Atherosclerosis Risk in Communities (ARIC) study who wore wrist-worn accelerometers and completed cognitive assessments. Major activity domains were time in bed and time out of bed, which were divided into 4 categories: SB, low-light (low-LIPA), high-light (high-LIPA), and moderate-to-vigorous physical activity (MVPA). Cognitive outcomes included global cognition, memory, executive function, and language performance. RESULTS: Across all cognitive domains, greater time spent in MVPA relative to other activity domains, including out-of-bed time, SB, and low-LIPA, was associated with better cognitive performance. In contrast, greater time spent in low-LIPA relative to other activity domains was consistently associated with poorer performance across all cognitive domains, and these associations were attenuated, but remained statistically significant, after adjustment for gait speed. Sedentary behavior was negatively associated with executive function only. CONCLUSIONS: The trade-off between time spent in MVPA and in low-LIPA is the objectively measured PA that was most strongly associated with cognitive abilities. Time spent in low-LIPA may be an important biomarker of physical health and cognitive impairment.