P041 Regional sleep-spindle changes in OSA after CPAP: a hdEEG study

Abstract Background and objective Sleep spindles are hallmark EEG features of N2 sleep and are important for sleep-dependent cognitive processes. Individuals with OSA show spindle deficits and altered spindle activity when compared to controls. Treatment of OSA with continuous positive airway pressure (CPAP) may restore spindle activity. However, the regional recovery of spindles and their morphology after CPAP has not yet been examined. Our high-density EEG study aimed to investigate the regional changes in sleep spindles in N2 sleep after CPAP treatment. Methods Nine males with moderate-to-severe OSA had sleep recordings using 256-channel hdEEG and cognitive tasks at baseline and after 3 months of CPAP. Artifact-free overnight HdEEG data were analysed using an automated spindle detection algorithm and spindle events (slow, 11-13 Hz; fast, 13-16 Hz) were detected for each electrode. We calculated N2 spindle density and characteristics: duration, amplitude, peak frequency, and peak-to-peak amplitude. Differences in regional and global spindle measures were assessed using paired t-tests and statistical nonparametric mapping. Results In this group of compliant CPAP users (age 51.5 ± 7.0, BMI 31.7 ± 5.4, nightly use 12.1 ± 6.3hrs), global spindle characteristics were not significantly different after treatment, relative to baseline. Regional EEG analysis showed higher slow and fast spindle amplitude in the central-parietal region, particularly around Cz, Pz, C3/C4 and P3/P4 electrode sites after 3 months CPAP treatment. Conclusion Our preliminary results suggest partial recovery of sleep spindle characteristics in men with moderate-to-severe OSA following CPAP. Further analyses will explore the relationship between regional spindle changes and memory and cognitive performance after treatment.