Identifying Brain Connectivity Changes in Combat Veterans with PTSD

Identifying Brain Connectivity Changes in Combat Veterans with PTSD

Posted: July 22, 2020
Identifying Brain Connectivity Changes in Combat Veterans with PTSD

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Researchers successfully tested an EEG-based method of assessing how and where brain connectivity is altered in combat veterans with PTSD, a possible aid to future treatment development.


Post-traumatic stress disorder (PTSD), which affects about 7% of American adults, is much more common in combat veterans. Like others with PTSD, combat vets with the disorder experience intrusive thoughts or memories related to trauma; impairments in both mood and cognition; may have a hair-trigger response to cues associated with experienced traumas; and may go far out of their way to avoid places, people, or experiences that they fear might cue such hyperarousal.

The country’s wars in Iraq and Afghanistan since 2001 have enabled researchers and clinicians to determine that more than one veteran in four who has been exposed to combat will develop PTSD symptoms. The rate varies according to the severity of the combat that was experienced as well as underlying biological factors which may make some people more resilient or vulnerable than others when facing trauma.

Pioneering research in recent years has suggested linkages between the presence of PTSD symptoms and specific changes in brain connectivity. These have been based on studies made with functional MRI (fMRI) brain scanning technology. This technology, however, is difficult to apply in clinical settings; it is both technically difficult to use and costly.

A Stanford University-based research team led by BBRF 2012 Young Investigator Amit Etkin, M.D., Ph.D., has had the objective of translating fMRI-based insights on changes in brain connectivity in PTSD to a technology that would be easier to use in the clinic, where it might help combat vets and others with PTSD. The results of their latest research were recently published in the American Journal of Psychiatry.

Dr. Etkin and colleagues tested their technological package on 36 healthy subjects, demonstrating its ability to make fine distinctions in brain connectivity across different brain regions. The team’s solution was based upon brain-wave readings made by using electroencephalography, or EEG technology. Specifically, EEG recordings were made when the brain is in its so-called resting-state, i.e., when not engaged with a specific cognitive task. The researchers’ object in these initial tests was to see if they could overcome technical issues.

They were satisfied that these tests enabled them to piece together a fine-grained “connectomic profile” of brain regions implicated in PTSD—a portrait of how different regions connect with one another. The key question was then whether this method would enable the team to see changes in brain area connections that fMRI studies have suggested may be occurring in PTSD. Assuming they were able to do so, the team also wanted to try to relate such connectivity changes with actual symptoms experienced by PTSD patients who had been exposed to combat.

Dr. Etkin’s team tested their EEG-based method in a group of 201 veterans who had been deployed to Iraq and/or Afghanistan: 95 were healthy controls without PTSD, while 106 met full or “subthreshold” criteria for PTSD. Most of the participants were men.

The trial revealed 74 brain region connections that were “significantly reduced” in PTSD. The most prominent area of under-connectivity was in a large section of the frontal lobe called the middle frontal gyrus. This underconnectivity was seen in slow-moving brain waves called theta waves. Such slow waves are associated with memory, emotion, and sensation. These findings were consistent with findings made in prior fMRI studies.

The team was also able to correlate the observed under-connectivity changes with symptoms in patients, involving working memory and inhibition.

The team hopes that their validation of the EEG-based method of analyzing brain connectivity in PTSD patients might support clinical efforts to develop more targeted and effective treatments, including non-invasive brain stimulation technology (such as rTMS, or repetitive transcranial magnetic stimulation) to target specific brain areas to boost connectivity—it is hoped, with therapeutic impact.