O005 Age related changes in sleep quantitative EEG and longitudinal relationship to cognitive function

Abstract Objectives Altered sleep microarchitecture including sleep spindles and decline in cognitive function occurs with advancing age. However, the longitudinal relationship between changes in sleep neurophysiology and cognition in middle-to-late life is currently unclear. This study examined sleep micro-architecture measured by electroencephalography (EEG) and cognitive performance in middle-aged and older men over a 10-year period. Methods 156 participants from the Florey Adelaide Male Ageing Study who reported no previous obstructive sleep apnoea diagnosis underwent home-based polysomnography and cognitive testing including mini mental state examination (MMSE) and trail-making tests A (visual attention) and B (executive function) at baseline (2010-2011) and follow up (2019-2020). Power spectral analysis of single-channel EEG (F4-M1) recordings at follow up (n=142) was performed. Baseline and follow-up sleep parameters including spindle metrics, and cognition were compared using paired t-tests, and associations examined with Pearson’s correlations. Results NREM (267.6 vs 299.2 minutes) and REM (57.0 vs 77.7 minutes) sleep was higher during follow up compared to baseline (p <0.001). NREM sleep spindle events (257.5 vs 351.7) and spindle density (0.95 to 1.17 events/minute) was higher at follow-up (p <0.001). Performance on the TMT was worse (TMT-A: 15.4 vs. 38.7 seconds, TMT-B: 74.9 vs. 93.7 seconds, p <.001), indicating cognitive decline in these domains. There was no change in MMSE. The change in sleep spindles and cognition were not correlated. Conclusions In this community-dwelling cohort of men, no longitudinal relationship between sleep spindles and cognitive function was observed. The unexpected increase in spindle activity across the 10-year follow-up warrants further exploration.