Increased Alpha-Wave Synchrony During Sleep Linked To PTSD

Combat-exposed veterans with post-traumatic stress disorder (PTSD) show increased synchrony in certain brain regions during sleep compared to their peers without PTSD, according to new findings.

"PTSD subjects showed increased alpha-band synchrony during non-REM sleep in the left fronto-parietal, left centro-parietal, and inter-parietal brain regions," Dr. Jaques Reifman of the US Army Medical Research and Development Command in Fort Detrick, Maryland, and colleagues write in Sleep. "Importantly, these trends were reproducible across consecutive nights and subpopulations. Thus, these alterations in alpha synchrony may be discriminatory of PTSD."

Disturbed sleep is a "hallmark symptom" of PTSD, the authors note, and finding objective measurements of sleep disturbance in these patients "could have important clinical implications."

Previous electroencephalography (EEG) studies have suggested differences in brain activity between people with and without PTSD, they add, but have had mixed results.

In the new study, Dr. Reifman and colleagues looked at two consecutive nights of EEG recordings from 78 combat-exposed male vets, including 31 with PTSD. They analyzed group differences in 90 synchrony pairs, with the first 47 consecutive patients serving as a discovery set and the following 31 as a replication set.

In the discovery set, which included 18 individuals with PTSD, five alpha-band pairs showed larger synchrony in PTSD, with effect sizes of 0.52-1.44. Similar effects were seen in the replication group, which included 13 individuals with PTSD.

Activity in some synchrony pairs was positively correlated with daytime cognitive performance.

Alpha synchrony in the fronto-parietal networks has been linked to vigilance, the authors note. "Together, these findings suggest that the increased alpha synchrony we observed in PTSD subjects during NREM sleep is associated with disturbed sleep (due to hypervigilance) and may influence cognitive memory processes," they conclude.

Dr. Reifman was not available for an interview by press time.

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