Heightened perception of anger driven by over-connected brain circuits in soldiers with PTSD, new study finds

By Emily de Medeiros

A new study led by The Hospital for Sick Children (SickKids) employed an advanced brain scanning technique to monitor brain activity and found that soldiers with post-traumatic stress disorder (PTSD) are more likely to perceive threatening facial expressions than those who are not affected by the disorder. The research published in the Jan. 20 online edition of Heliyon is a partnership with the Canadian Armed Forces.

The research team monitored the brain activity of 20 soldiers with PTSD and 25 soldiers without. When participants were shown pictures of happy and angry faces, the soldiers’ behavioural reactions to the images were similar, but the use of brain scanning technologies indicated that their brain responses were very different.

Researchers found that a large number of brain regions were over-connected in soldiers with PTSD when they looked at angry faces, but not while looking at happy faces.“The heightened perception of anger in PTSD is driven by complicated brain circuitry where the mechanism of communication among a number of key regions that control fear and emotion is over-connected,” explains lead author Dr. Benjamin Dunkley, MEG Clinical Associate in the Department of Diagnostic Imaging at SickKids.

PTSD is a serious and complicated psychiatric condition that may affect individuals who have experienced some type of trauma. A study by the Canadian Armed Forces estimates that 86 per cent of people serving in the armed forces will experience some kind of trauma, and around seven per cent of those in the Canadian military develop PTSD at some point in their lives. Findings suggest the risk is higher in soldiers in comparison to civilians.

PTSD can be difficult to assess because symptoms such as memory loss and attention problems are very similar to other symptoms in brain injuries like concussion. Researchers used a sophisticated brain scanning technique known as magnetoencephalography (MEG) to look at activity in the brain, and found that the amygdala, a part of the brain crucial to emotional reactions, and the ventral medial prefrontal cortex (vmPFC), which is important for inhibiting fear, showed significantly different connectivity patterns in the soldiers with PTSD.  “We were surprised to find that key brain circuits were over-connected in PTSD,” says Dunkley. “This may be why emotional responses are so immediate and automatic, and why threatening faces are such a trigger.”

In similar studies, researchers previously used magnetic resonance imaging (MRI) to monitor brain activity but there is a many-second time-lag between the brain response and measurement, and this technique measures blood flow associated with brain activity, but not directly the activity itself. Researchers agree that the advanced technique of using MEG is pushing the boundaries of what is known about the human central nervous system by directly measuring brain activity in real-time to provide a more detailed description of brain function and how regions communicate with one another. “These techniques are increasingly being used to study psychiatric and neurological conditions, providing valuable information about the neurobiological basis of such disorders,” says Dunkley.

These findings emphasize the challenges of living with and treating PTSD. Understanding the brain’s connectivity responses to angry expressions in people with PTSD may help clinicians and researchers develop improved processes in the diagnosis and treatment of PTSD, and better identify when soldiers are ready to return to deployment.

This research was funded by the Defence Research and Development Canada (DRDC), the Canadian Forces Health Services and SickKids Foundation.

This paper is an example of how SickKids is contributing to making Ontario Healthier, Wealthier and Smarter.