0727 Association of sleep quality with memory functions among dementia-free, middle- and older-age, rural Indians

Introduction Sleep is known to be involved in cognitive processes, such as memory consolidation. Poor sleep is a potential risk factor for dementia. However, whether it is associated with decreased memory functions among dementia-free individuals is not well known. This study aims to investigate the effect of sleep quality on memory functions among middle and older-age adults from a rural Indian population. Methods Participants were dementia-free, rural Indians (≥ 45 years) recruited as part of an ongoing, prospective, aging cohort study, namely Srinivaspura Aging, NeuroSenescence, and COGnition (SANSCOG) study. Cross-sectional (baseline) data on sleep quality was obtained using Pittsburgh Sleep Quality Index (PSQI). Memory functions (at baseline) were assessed using subtests, namely immediate recall, delayed recall, name-face association, semantic fluency, phonemic fluency, and semantic association, from a culturally validated computerized neurocognitive test battery. Clinical Dementia Rating (CDR) was used to classify subjects based on their cognitive status into cognitively healthy (CDR=0) and MCI (CDR=0.5). Linear regression models, unadjusted and adjusted with cognitive status, age, gender, and depression, were used for analysis. Results In the unadjusted linear regression model 1, we found no association between sleep quality and the different subtests of memory. However, in model 2 (adjusting for cognitive status), sleep quality in persons with MCI was significantly associated with memory functions. Model 3 (model 2 + age) found that sleep quality in higher ages in MCI explained a significant variance in the association between sleep and subtests of memory function compared to cognitively healthy individuals. Model 4 (model 3 + gender) suggested that with increasing age, gender was significantly associated with sleep quality and memory among individuals with MCI compared to cognitively healthy individuals. Further, model 5 (model 4+ depression) found that depressed individuals with MCI showed a significant association between sleep quality and memory functions compared to those without depression. Conclusion When adjusted for cognitive status, age, gender and depression, there was significant association of sleep quality and memory functions, pointing to the important role of sleep in memory functions among middle and older-aged individuals without dementia. Support (if any) SANSCOG study is funded through the Centre for Brain Research by Pratiksha Trust