Sleep disturbances in the memory clinic: Associations with clinical features and neuropsychological performance

Abstract

AbstractBackgroundThe prevalence of sleep disturbances increases in ageing and may further increase in neurodegeneration. In a memory and cognition (MC) clinic setting, our study aims to: 1) determine the rates of various sleep disturbances including obstructive sleep apnoea (OSA), short and long sleep duration, insomnia, sleep quality, and rapid eye movement sleep behaviour disorder (RBD); and 2) examine whether these sleep disturbances are associated with neuropsychological performance in older adults without dementia.MethodWe captured data between 2009 and 2022 from a MC clinic for older adults aged over 50 with new cognitive and/or mood concerns. Self‐reported history, pulse oximetry, and polysomnography (PSG) captured rates of OSA. Actigraphy (>7 days) was used to measure sleep duration (defined short duration as <6 hours and long duration as >9 hours). Validated self‐report questionnaires were used to capture insomnia, sleep quality, and RBD. We examined group differences between those with and without sleep disturbances in the following cognitive composites: verbal learning and memory, processing speed, executive function, and language skills.ResultsWe recruited 1016 participants (mean age = 66.9 (SD = 9.0), mean MMSE = 28.3 (SD = 2.2), male = 436 (43%)). For rates of OSA, 15% (n = 152/1016) self‐reported history of OSA, 76% (n = 383/504) had OSA as classified by PSG, 84% (n = 115/137) had OSA as classified by pulse oximetry. From actigraphy data, 10% (n = 55/566) had short sleep and 5% (n = 29/566) had long sleep duration. From self‐report data, 15% (n = 85/579) had moderate or severe clinical insomnia, 61% (n = 544/893) reported having poor sleep quality, 10% (n = 56/579) had RBD. Individuals with OSA (from PSG) performed worse in verbal learning compared to those without OSA (p<0.05). Individuals who had long sleep duration performed worse on both verbal learning (p<0.05) and memory (p<0.05) than those with short sleep and normal sleep duration. There were no other significant group differences in cognition outcomes, amongst the other sleep disturbance groups (p>0.05).ConclusionIn MC clinics, there are very high rates of sleep disturbance in this at‐risk population. The large discrepancy in rates of OSA between self‐reported history and PSG suggests OSA is under‐diagnosed. Sleep disturbances may be associated with cognitive outcomes, in particular learning and memory.