Associations between 24-hour movement behavior and cognition in older adults at risk for dementia: A compositional data analysis.

OBJECTIVES: To explore the associations between 24-hour movement behavior (24HMB) and cognition in older adults at risk for dementia. METHODS: This study adopted a cross-sectional design. Community-dwelling older adults at risk for dementia, including subjective cognitive decline and mild cognitive impairment, were recruited from community health centers and memory clinics. Global cognition was assessed by the Montreal Cognitive Assessment scale. 24HMB was measured by wrist-worn ActiGraph for consecutive 7 days. Compositional regression model and compositional isotemporal substitution model were used to analyze the relations between hypothetical time reallocation among 24HMB compositions and global cognition. RESULTS: A total of 136 participants were included in the analysis. Compositional regression analysis indicated that a greater relative proportion of time spent in moderate-to-vigorous physical activity (MVPA) was positively associated with global cognition after adjusting for covariates. Compositional isotemporal substitution models revealed that the hypothetical reallocation of 10, 20, or 30 min from sedentary behavior or sleep to MVPA was related to theoretically better global cognitive performance. Additionally, reallocating time from sleep to light physical activity was potentially associated with better cognitive performance, although this finding lacked robustness. No other significant associations were observed. CONCLUSION: The 24HMB composition, particularly a greater relative proportion of time spent in MVPA, is associated with better cognition in older adults at risk for dementia. Hypothetical time reallocation from sedentary behavior or sleep to MVPA is theoretically associated with better cognitive performance.