0893 Long objective sleep duration is a marker of cognitive impairment among older elderly: findings from the Cretan Aging Cohort

Abstract

Abstract Introduction We have previously shown that although sleep duration is similar between cognitively non-impaired (CNI) elders and patients with Mild Cognitive Impairment (MCI), long sleep duration is associated with disease severity in patients with multi-domain MCI and Dementia. Our aim was to examine the associations between sleep duration and cognitive status in subjects with CNI and MCI followed 8 years later. Methods A sub-sample of 110 participants (77.3% females) were recruited from a large population-based cohort in Crete, Greece of 3,140 older adults (>60 years). Participants with an initial diagnosis of CNI (n=57) and MCI (n=53) (mean age at baseline=72.7 years [SD=6.8]) were followed-up 8 years later (mean age at follow up=80.5 years [SD=6.7]). All participants underwent neuropsychiatric/neuropsychological evaluation (baseline & follow-up) and a 7-day 24h actigraphy (follow-up). Sleep duration measured as night Total Sleep Time (TST) at follow-up was compared between the diagnostic groups using ANCOVA controlling for age, gender, depression symptom severity, psychotropic medication. Long sleep duration was defined by values >75% percentile of the total sample distribution on each sleep index. Results At follow up 62.7% of participants have deteriorated cognitively with 29 being diagnosed with CNI, 49 with MCI and 32 with dementia. Patients with dementia had significantly longer night TST (mean=493, SD=106 min) than persons with MCI (mean=453, SD=68 min, p=0.05) who in turn had longer night TST than CNI participants (mean=409, SD=58 min, p=0.02). Also, long night sleep duration was significantly more prevalent among dementia patients and MCI compared to CNI individuals [67.7% vs. 36.7% vs. 10.3%, respectively; all p< 0.02)]. Conclusion Our study confirms and expands previous findings that objective long sleep duration is a marker of worse cognitive status in elderly with MCI or Dementia and that this association is even stronger in old-old individuals. Support (if any) National Strategic Reference Framework (NSRF)-Research Funding Program: THALES entitled “UOC-Multidisciplinary network for the study of Alzheimer’s Disease” Grant Cod: MIS 377299 HELLENIC FOUNDATION FOR REASEARCH AND INNOVATION (HFRI)- Research Funding Program: ELIDEK entitled “Sleep Apnea (OSA) and poor sleep as Risk Factors for decreased cognitive performance in patients with Mild Cognitive Impairment: the Cretan Aging Cohort (CAC)”, Grant Cod: HFR1-FM17-4397