The relationship between sleep and cognitive performance on tests of pattern separation
Study objectives: Sleep disturbances are considered both a risk factor and symptom of dementia. The present research aimed to identify cognitive tests that are sensitive to sleep-dependent cognition, focusing on cognitive tests designed to evaluate the earliest cognitive changes in dementia. Methods: In Experiment 1, we recruited younger (n=89) and older (n=40) adults and remotely monitored their sleep patterns for 7 consecutive days using actigraphy and sleep diaries. On day 7, participants completed a battery of cognitive tests, which included the Prodromal Alzheimer's and MCI battery from the Cambridge Neuropsychological Test Automated Battery (CANTAB) and the Mnemonic Similarity Task (MST). In Experiment 2, we examined the effects of a night of total sleep deprivation on cognitive performance in young adults. We observed a sleep deprived group (n=16) overnight in the lab. The rested control group (n=32) slept normally at home. Results: In Experiment 1, there was a significant relationship between performance on MST and total sleep time in the older adults. There were no relationships between cognitive performance and sleep quantity or quality in the younger adults. In the older adults, Montreal Cognitive Assessment (MoCA) scores were correlated with performance on the CANTAB and MST. In Experiment 2, the young adults who underwent 24-hour sleep deprivation performed worse than the rested participants on the MST task. Conclusion: Performance on cognitive tests designed to assess pattern separation are sensitive to sleep patterns, particularly in older adults and should be evaluated for potential use as clinical trial outcome measures for sleep-promoting treatments.