Cognitive tests of pattern separation as sleep-sensitive measures in middle-aged and older adults: An exploratory study

Sleep disturbances are considered both a dementia risk factor and symptom. The present research aimed to identify cognitive tests sensitive to objective sleep quantity or quality, focusing on tests designed to evaluate the earliest cognitive changes in dementia. We recruited adults who were 50 years or older and remotely monitored their sleep patterns for 7 consecutive days using wrist actigraphy and sleep diaries. On day 7, participants completed different cognitive tests; the Psychomotor Vigilance Task (PVT), the Prodromal Alzheimers and Mild Cognitive Impairment battery from the Cambridge Neuropsychological Test Automated Battery (CANTAB), the Mnemonic Similarity Task (MST), taxing pattern separation, and the Montreal Cognitive Assessment (MoCA). The final sample included 34 participants (mean age: 65.56, SD: 9.57). There were significant correlations between objective sleep quantity and PVT and MST performance. MoCA scores were correlated with performance on CANTAB and MST. Objective sleep quantity predicted MST performance when controlling for age, sex, and education. Tests of pattern separation are sensitive to objective sleep quantity and early cognitive changes associated with dementia. The sensitivity of pattern separation tests to sleep should be evaluated in a larger study, aiming to identify suitable clinical trial outcome measures for sleep-promoting treatments in older adults.