Are Alterations in Alpha Synchrony Discriminatory of PTSD?

Research Paper Title

Alterations in Sleep EEG Synchrony in Combat-Exposed Veterans With PTSD.

Background

The researchers assessed whether the synchrony between brain regions, analysed using electroencephalography (EEG) signals recorded during sleep, is altered in subjects with post-traumatic stress disorder (PTSD) and whether the results are reproducible across consecutive nights and sub-populations of the study.

Methods

Seventy-eight combat-exposed veteran men with (n = 31) and without (n = 47) PTSD completed two consecutive laboratory nights of high-density EEG recordings. They computed a measure of synchrony for each EEG channel-pair across three sleep stages [rapid eye movement (REM) and non-REM stages 2 and 3] and six frequency bands.

The researchers examined the median synchrony in nine region-of-interest (ROI) pairs consisting of six bilateral brain regions (left and right frontal, central, and parietal regions) for ten frequency-band and sleep-stage combinations.

To assess reproducibility, they used the first 47 consecutive subjects (18 with PTSD) for initial discovery and the remaining 31 subjects (13 with PTSD) for replication.

Results

In the discovery analysis, five alpha-band synchrony pairs during non-REM sleep were consistently larger in PTSD subjects compared to controls (effect sizes ranging from 0.52 to 1.44) across consecutive nights: two between the left-frontal and left-parietal ROIs, one between the left-central and left-parietal ROIs, and two across central and parietal bilateral ROIs.

These trends were preserved in the replication set.

Conclusions

PTSD subjects showed increased alpha-band synchrony during non-REM sleep in the left fronto-parietal, left centro-parietal, and inter-parietal brain regions.

Importantly, these trends were reproducible across consecutive nights and sub-populations. Thus, these alterations in alpha synchrony may be discriminatory of PTSD.

Reference

Laximinarayan, S., Wang, C., Ramakrishnan, S., Oyama, T., Cashmere, J.D., Germain, A. & Reifman, J. (2020) Alterations in Sleep EEG Synchrony in Combat-Exposed Veterans With PTSD. Sleep. doi: 10.1093/sleep/zsaa006. Online ahead of print.

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