The relationship between sleep and cognitive performance on tests of pattern separation

Study objectivesSleep disturbances are considered both a risk factor and symptom of dementia. The present research aimed to identify cognitive tests in which performance is associated with objective sleep quality or quantity, focusing on cognitive tests designed to evaluate the earliest cognitive changes in dementia. MethodsWe recruited older adults (50 years of age or older) and remotely monitored their sleep patterns for 7 consecutive days using wrist actigraphy and sleep diaries. On day 7, participants completed a battery of cognitive tests, which included the Psychomotor Vigilance Task (PVT), the Prodromal Alzheimers and Mild Cognitive Impairment battery from the Cambridge Neuropsychological Test Automated Battery (CANTAB), and the Mnemonic Similarity Task (MST), designed to tax pattern separation. The participants were also assessed with the Montreal Cognitive Assessment (MoCA). ResultsThe final sample included 34 participants (mean age: 65.56, SD: 9.57). There were significant correlations between objective total sleep time and PVT and MST performance. MoCA scores were correlated with performance on CANTAB and MST. Objective total sleep time also predicted MST performance when controlling for age and gender. ConclusionsPerformance on cognitive tests designed to assess pattern separation are sensitive to older adults objective sleep duration and the early cognitive changes associated with dementia. MST should be evaluated for potential use as a clinical trial outcome measure for sleep-promoting treatments in older adults. Statement of SignificanceThere is growing emphasis on the importance of sleep as a potential therapeutic target for neurodegenerative diseases (e.g., Alzheimers disease). Identifying cognitive measures that are sensitive to both sleep and the earliest cognitive changes associated with dementia are needed for use as outcome measures in clinical trials evaluating the effectiveness of sleep-promoting interventions. Our research addresses this need by investigating the relationship between sleep patterns and performance on cognitive tests designed to assess the earliest cognitive changes in dementia. Our results suggest that cognitive tests designed to assess pattern separation are uniquely sensitive to sleep quantity in older adults.