0075 Individual Differences in Habitual Sleep Discontinuity Predict Memory Consolidation and Supporting Neural Activity

Introduction Numerous studies manipulating sleep (i.e., deprivation, intervening naps between encoding and retrieval) have shown that sleep facilitates episodic memory consolidation in young, healthy adults. The relationship in older adults is more mixed, though generally supportive of age-related attenuations in sleep-dependent memory consolidation. However, studies using manipulations of sleep or a single night of sleep architecture may omit potentially important information about individual differences in one’s habitual sleep patterns that may contribute to the episodic memory performance across age. There is great interest in determining if well-known age-related impairments in sleep quality are related to those in episodic memory consolidation and the neural activity supporting memory. Methods As part of an ongoing study, we recruited samples of cognitively unimpaired younger and older adults and measured their habitual sleep using a wrist-worn accelerometer for 1 week. Principle component analysis (PCA) was used to reduce data dimensionality and identify sleep components. We recorded their electroencephalography (EEG) as they performed an object-scene associative memory task with immediate and delayed (48 hours) retrieval assessments. Participants were asked during both retrieval phases if object-scene pairs were new, matched or did not match pairs that were presented during encoding. Memory retention (delayed-immediate d’) was used as the index of consolidation, correcting for each participant’s learning level. Results Across age groups, higher levels of habitual sleep discontinuity, which were elevated in older adults, were associated with reduced memory retention/consolidation estimates (t(11) = -2.74, p = 0.02, d = 0.81) and neural activity during delayed retrieval associated with successful recovery of retained memories (rho = 0.499, rho-value = 0.015). Conclusion These results support the idea that age-related increases in habitual sleep discontinuity may contribute to age-related reductions in sleep-dependent episodic memory consolidation, and the neural mechanisms supporting successful recovery of consolidated memories. Support (if any) This work was supported by the NIA # R21AG064309.