1072 Post-traumatic Stress Disorder Is Associated With Increased Oscillatory Frequency Of Sleep Spindles

Introduction Patients with post-traumatic stress disorder (PTSD) often suffer from sleep disturbances. Sleep spindles are an electrophysiological hallmark of non-rapid eye movement sleep and believed to be involved in sleep protection and sleep-dependent memory consolidation. Here, we sought to examine whether sleep spindles are altered in PTSD and whether the findings are reproducible across nights and subsamples of the study population. Methods We obtained 64-channel electroencephalogram (EEG) recordings from 78 combat-exposed Veteran men with (n = 31) and without (n = 47) PTSD during two consecutive nights of sleep. We identified slow (10-13 Hz) and fast (13-16 Hz) sleep spindles during N2 and N3 sleep using an automatic algorithm and performed topographical analyses of spindle parameters (amplitude, duration, oscillatory frequency, and density) on both nights. To assess reproducibility, we used the first 47 consecutive participants (18 with PTSD) for initial discovery and the remaining 31 participants (13 with PTSD) for replication assessment. Results In the discovery analysis, compared to participants without PTSD, those with PTSD exhibited 1) increased oscillatory frequency of slow spindles over the antero-frontal regions on both nights (Night 1: p = .020, Cohen’s d = 0.92; Night 2: p = .014, Cohen’s d = 1.07) and 2) increased oscillatory frequency of fast spindles over the centro-parietal regions on the second night (p = .018, Cohen’s d = 0.76). Notably, these trends were preserved in the replication analysis. In contrast, we found no significant group differences in the amplitude, duration, or density of slow or fast spindles. Conclusion The elevated sleep-spindle frequency in PTSD may reflect reduced thalamocortical inhibition and, hence, deficient sleep protection. Our findings provide the basis for an initial understanding of sleep-spindle abnormalities in PTSD. The findings, if independently validated, may assist in the development of sleep-focused diagnostics and interventions for PTSD. Support This work was sponsored by U.S. Defense Health Program (grant No. W81XWH-14-2-0145) and managed by the U.S. Army Military Operational Medicine Program Area Directorate, Ft. Detrick, MD. The study was also supported by the Clinical and Translational Science Institute at the University of Pittsburgh (UL1 TR001857).