0103 The inverse relationship between Cognitive Performance and Non-stationarity during Stage 1 and Rapid Eye Movement Sleep in Older Adults: Arousals and Leg Movements

Abstract

Introduction In sleep recordings, Arousals and Leg Movements (LMs) in Older Adults (OAs) represent non-stationarities that are often avoided and are rejected when linear quantitative analyses are performed. Nevertheless, their frequency is fundamental to evaluate the health status of OAs, but there is little work on the influence of these events on cognitive performance according to sleep stages especially in subjects with Mild Cognitive Impairment (MCI); therefore, the frequencies of arousals and LMs were obtained and correlated with cognitive performance. Methods Neuropsi, a test validated in Mexico (100.2 ± 12), and the Mini-Mental State Examination (MMSE, 27.7 ± 2) were administered, as well as other geriatric tests to 14 OAs (66.5 ± 7; 9.7 ± 4 years of education). All subjects underwent one night PSG. Sleep stages, arousals and LMs were scored visually by two experts and were detected automatically by the MEDICID-5 software that follows the AASM standards. Pearson correlation analyses were carried out separately between the total number of arousals and LMs and the number of both events during each sleep stage and the total score of the two cognitive tests. Results Although there was not a significant correlation between the total number of arousals and LMs and cognitive performance on the Neuropsi test or the MMSE, a negative correlation was found between the frequency of arousals and N1 (r = - 0.52). Furthermore, during REM sleep, a positive correlation between the Neuropsi and the number of arousals and the Neuropsi and the number of LMs was observed (arousals, r = 0.55; LMs, r = 0.53). Conclusion Even when both NREM sleep N1 stage and REM sleep are similar and differ especially by the EMG status, REM sleep non-steadiness may be more important to preserve cognitive performance due to its association with executive functions and its inherent phasic REM sleep (i.e., rapid eye movements) than N1 stability.