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

Background The 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. Method We 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 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. Results We 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