P031 ANS activitposy during habitual sleep is associated with impaired cognition.

Abstract Introduction Rescue & Recovery Workers (RRWs) exhibit a high prevalence of obstructive sleep apnea (OSA), insomnia, post-traumatic stress disorder (PTSD) and are at elevated risk of cognitive impairment. Proxy measurement of autonomic-nervous-system (ANS) activity may provide a useful way to identify individuals with heterogenous sleep disturbances who are at greatest risk of dementia. Here we use multi-night cardio-pulmonary-coupling (CPC) monitoring to investigate whether ANS-sleep instability impairs cognitive functioning. Methods Twenty-two RRWs (4 female, ages 49-75) completed neuropsychological testing, providing functioning across memory, executive, attention and language domains. At-home CPC monitoring via a wearable ring was obtained for 7-15 nights prior to in-laboratory polysomnography. Proprietary CPC analysis rendered estimations of ANS-sleep instability (low-frequency-coupling (LFC): fragmentation and periodicity). Average and variability (Root Mean Squared of Successive Differences-RMSSD) statistics were calculated for CPC metrics and were correlated with cognitive domain functioning using Pearson’s co-efficient. Results Six participants (27%) had a PTSD diagnosis and 11(50%) had an insomnia severity index ≥8. On PSG, 12(55%) had OSA (AHI > =15). Sex, age and education-adjusted executive scores were positively correlated with night-to-night variability in LFC-fragmentation (R = 0.57,p=.007) and LFC-periodicity (R = 0.44,p=.045). Language scores correlated with variability in LFC-periodicity (R = 0.47,p=.03). Multi-night averages of ANS-sleep instability were not associated with cognition. Discussion Greater variability in ANS measures of sleep instability are associated with better executive and language functioning, perhaps akin to the relationship between greater heart rate variability and better health. Analysis of available overnight plasma for markers of neurodegeneration (tau and NfL) in this population will determine whether this relationship extends beyond cognition.