Patterns of Physical Activity and Sedentary Behavior for Older Adults with Alzheimer's Disease, Mild Cognitive Impairment, and Cognitively Normal in Hong Kong

Background: Alzheimer's disease (AD) is the most common form of dementia, and mild cognitive impairment (MCI) is a transitional phase between healthy cognition and dementia. Physical activity (PA) has protective effects on cognitive decline. However, few studies have examined how PA and sedentary behavior is structured throughout the day in older adults across varied cognitive status in Hong Kong. Objective: This study aimed to compare patterns of PA and sedentary behavior among individuals with AD, MCI, or normal cognition living in Hong Kong. Methods: Participants in the MrOs and MsOs Hong Kong cohort study and the Hong Kong AD biomarker study (n=810) wore a wrist-worn accelerometer for 7 days in free-living environment. Patterns of PA in wake time and in-bed time, and detailed analysis of sedentary bouts were compared between groups using analysis of covariance adjusting for covariates. Results: Participants with MCI and low MoCA only did not differ from their cognitively normal peers in PA and sedentary behavior. Nevertheless, when comparing to the others, participants with AD exhibited significantly lower average daily counts per minute during the day (p<0.05), and tended to start their activity later in the morning. AD participants spent a larger proportion of time in sedentary behavior (p<0.05) and had more sedentary bouts≥30 minutes (p<0.05). Conclusions: The pattern of PA and sedentary behavior was different between individuals with AD and the others. Cognitive status may alter the purpose and type of PA intervention for AD individuals.