Sleep disturbance and association with cognitive and functional trajectories in all cause dementia: The Cache County Dementia Progression Study

Abstract

AbstractBackgroundSleep disturbance is common in older adults, with a prevalence rate of approximately 25%. Sleep disturbance has been associated with increased risk for Alzheimer’s disease (AD), brain Aß deposition, and worse cognition in older adults in general. Few studies have examined the association between sleep disturbance and cognitive or functional decline after the onset of dementia. We examined this issue in a population‐based cohort of persons with dementia.MethodFive hundred eighty‐two participants (aged 65+, 60.3% female) with dementia from the Cache County Memory Study were followed for a mean (sd) of 2.47 (2.72) years, and maximum of 13.28 years. Mean (sd) age of dementia onset was 83.49 (6.29) years. A majority (81.3%) had a high school diploma/GED. Cognition was assessed at baseline and semi‐annual follow‐ups with the Mini‐Mental State Exam (MMSE) and functional status with the Clinical Dementia Rating sum‐of‐boxes (CDR‐sum). Sleep disturbance was based on the sleep domain from the Neuropsychiatric Inventory, or if lacking, a question about the subject being “troubled by sleep problems, insomnia.” Presence of depression was also determined from the NPI. Sleep disturbance (time varying) was examined in separate linear mixed effects models to predict changes in MMSE and CDRsum, controlling for age, gender, education, depression (yes/no) and presence of APOE E4 allele.ResultPrevalence of sleep disturbance was 29.7%. The association between sleep disturbance and cognitive and functional outcomes varied by dementia type (p interactions < .001). Compared to those with Alzheimer’s disease and sleep disturbance, individuals with vascular dementia and sleep disturbance exhibited worse (higher) CDR‐Sum scores across time (M_difference = ‐1.55, SE = .41, p < .001, d = .27) while individuals with “other dementias” and sleep disturbance performed worse on the MMSE (M_difference = 2.14, SE = .55, p < .001, d = .38) as did APOE4 carriers (M_difference = 1.45, SE = .35, p < .001, d = .26).ConclusionIndividuals with various dementia types and those with an APOE E4 allele in combination with sleep disturbance had worse cognitive and functional trajectories. Future work will examine effects of sleep medication use on dementia trajectory.