Effects of obstructive sleep apnea on human spatial navigational memory processing in cognitively normal older individuals.

Abstract

STUDY OBJECTIVES\nObstructive sleep apnea (OSA) prevalence increases with age, but whether OSA-related sleep disruption could interrupt the processing of previously encoded wake information thought to normally occur during sleep in cognitively normal older adults remains unknown.\n\n\nMETHODS\nFifty-two older (age = 66.9 ± 7.7 years, 56 % female), community-dwelling, cognitively normal adults explored a 3D maze environment and then performed 3 timed trials before (evening) and after (morning) sleep recorded with polysomnography (PSG) with a 20-minute morning psychomotor vigilance test (PVT).\n\n\nRESULTS\nTwenty-two (22) subjects had untreated OSA (Apnea Hypopnea Index (AHI4%) ≥ 5/hour) where severity was mild on average [median (interquartile range (IQR))] AHI4% = 11.0 (20.7)/hour) and 30 subjects had an AHI4% < 5/hour. No significant differences were observed in overnight percent change in completion time or in the pattern of evening pre-sleep maze performance. However, during the morning post-sleep trials, there was a significant interaction between OSA group and morning trial number such that participants with OSA performed worse on average with each subsequent morning trial, whereas those without OSA showed improvements. There were no significant differences in morning PVT performance suggesting that vigilance is unlikely to account for this difference in morning maze performance. Increasing relative frontal slow wave activity (SWA) was associated with better overnight maze performance improvement in participants with OSA (r= 0.51, p = 0.02) but not in those without OSA, and no differences in slow wave activity were observed between groups.\n\n\nCONCLUSIONS\nOSA alters morning performance in spatial navigation independent of a deleterious effect on morning vigilance or evening navigation performance. Relative frontal slow wave activity is associated with overnight performance change in older subjects with OSA, but not those without.