[P2–569]: SELF‐REPORTED SLEEP DISTURBANCES AND COGNITIVE DECLINE IN THE ELDERLY: ATTENUATING THE RISK BY PHYSICAL ACTIVITY

Background:Sleep disturbances and cognitive impairment are common in the elders. Emerging evidences have shown that sleep disturbances are correlated with cognitive decline. However, it is unclear how physical activity modify the association of sleep disturbance with cognitive decline. Methods:A prospective cohort study with 605 elders ≥ 65 years were recruited from a checkup program at baseline (2011-2013), and around 500 subjects were followed two years later. Self-reported sleep disturbances was assessed by self-reported insomnia and restless sleep (≥1 session/ week). Physical activity was assessed by International Physical Activity Questionnaire. Walking or minimally active means ≥150 mins/week walking or weekly exercise. Global cognition and logical memory were evaluated by Montreal Cognitive Assessment and Wechsler Memory Scale-third edition. The outcome of this study was cognitive decline, i.e. the lowest tertile of cognitive change between baseline and follow-up. Multivariable logistic regression was used to explore the association between self-reported sleep disturbances, physical activity and cognitive decline over 2-year follow-up adjusting for age, gender, education years and apolipoprotein E ϵ4 status. Results: About 33% and 13% of the elders reported insomnia and restless sleep. Elders who are physically active had a lower rate of insomnia (22.9%) or restless sleep (7.2%). Elders with insomnia had increased risk of decline on global cognition [adjusted odds ratio (aOR)=1.54 and on the decline of logical memory (aOR= 1.82 to 3.18). Self-reported restless sleep also increased risk of the decline of logical memory (aOR= 1.44 to 2.61). After stratification by sleep related variables, among elders without insomnia, regular walking (150 mins/week or more walking) protected against the decline of logical memory II (aOR=0.37-0.44) compared with those without or with low walking. Among elders with restless sleep, minimal physical activity (≥ 600 MET-min) protected against the decline of logical memory II (aOR=0.22). Among elders without restless sleep, those with regular walk showed protective effect on logical memory II (aOR=0.55-0.49). Conclusions: Self-reported sleep disturbances, including insomnia and restless sleep, were associated with increased the risk of decline on global cognition and logical memory. Physical activity may reduce cognitive decline and provide useful information for the prevention of dementia in the preclinical phase.