Self‐reported sleep duration is not associated with pet amyloid deposition in the oldest‐old: The 90+ Study

Abstract

AbstractBackgroundSome, but not all cross‐sectional studies have suggested a relationship between sleep and PET‐measured amyloid burden in older adults without cognitive impairment. It is hypothesized that amyloid clearance from the brain is related to sleep duration. Our aim is to examine the cross‐sectional association between self‐reported sleep duration and amyloid accumulation in the oldest‐old (90+ years), a group with high prevalence of amyloid burden and sleep changes.MethodWe analyzed data on 115 participants of The 90+ Study, a longitudinal study of aging and dementia, who reported their monthly average nocturnal sleep duration using the Medical Outcomes Study Sleep Scale (MOS) and had 18F‐florbetapir (amyloid) PET. Sleep duration was categorized as <8, 8 (reference, mean sleep duration) and >8 hours. Standardized uptake value ratio (SUVr) was computedfor the posterior cingulate/precuneus (region affected early by Alzheimer’s neuropathological changes) and analyzed both as continuous and binary (SUVr <0.8 vs. ≥0.8) variables. Cognitive diagnosis from the clinical evaluation closest to PET was used to categorize participants as normal vs. cognitively impaired (dementia or cognitive impairment without dementia). We analyzed sleep duration in relation to SUVr using multiple linear regression and logistic regression, controlling for age, Geriatric Depression Scale score, sleep medications, and cognitive diagnosis at the time of MOS; and additionally sex, education, APOEe4 status, and time between MOS and PET.ResultAt the time of MOS, average age was 95 years, 60% were women, 65% had normal cognition. The average sleep duration was 8 hours. Average PET SUVr was 0.77 and 33% of participants were amyloid positive. Amyloid burden was higher (0.80 vs. 0.75) and sleep was longer (8.14 vs. 7.51 hours) in cognitively impaired compared to cognitively normal participants (Table 1). Sleep duration was not associated with amyloid accumulation in the entire group analysis or when stratified by cognitive diagnosis (Tables 2 and 3, Figure 1).ConclusionIn this group of oldest‐old individuals, self‐reported sleep duration was not associated with amyloid accumulation in the posterior cingulate/precuneus. It is possible that amyloid accumulation is not associated with sleep in this age group or it is associated with other sleep‐related measures.