Understanding one’s susceptibility to developing post-traumatic stress disorder (PTSD) is important.
In a study from Tufts University, scientists found a brain marker that indicates vulnerability to the disorder.
They discovered that heightened activation in one particular brain region in response to seeing surprised and neutral facial expressions appears to be tied to developing PTSD.
A number of symptoms define PTSD, but the researchers were particularly interested in hypervigilance—always feeling that you need to monitor your environment for potential threats”.
Previous research had found that hypervigilance may lead people with PTSD to respond with fear to signals that are ambiguous or not clearly threatening—for example, hearing a firecracker might trigger fears of gunshots.
In the study, the team examined male identical twin pairs using fMRI studies of brain activation.
By studying identical twins, who share the same genes, the researchers could show which traits are familial and which are not.
In a set of 12 identical twin pairs, one twin had experienced trauma and developed PTSD, while the other was not trauma-exposed.
A set of 15 identical twin pairs were used as a control group. One member of that twin set had experienced trauma but not developed PTSD, and the other was not exposed to trauma.
The research team focused on two brain mechanisms.
The first was heightened activation of the amygdala, a part of the brain that is involved in processing fear-related stimuli, resulting in the fight, flight, or freeze response.
The second mechanism is the activation of the medial frontal gyrus, a part of the prefrontal cortex involved in inhibiting the amygdala’s response to things that are in fact not threatening.
While the researchers were expecting the men who had PTSD to show greater activation of the amygdala when observing faces with surprised looks, they hadn’t expected that the participants would have the same response to neutral facial expressions.
Tellingly, the same was true in the participants’ trauma-unexposed twins who didn’t have PTSD.
On the other hand, the group who had experienced trauma but not been diagnosed with PTSD did not show the same heightened amygdala response to either the surprised or neutral faces.
These findings may mean that people who have greater amygdala activation before experiencing trauma may be more vulnerable to developing PTSD.
The findings may also imply that if a person shows preexisting vulnerability to developing PTSD—through heightened amygdala activation—and experiences a traumatic event.
A final takeaway from the study is that the decreased reactivity in the medial frontal gyrus, which tamps down an excessive fear response, occurred only in the group with PTSD.
This suggests that the lowered response in the prefrontal cortex is an acquired characteristic of PTSD.
If you care about mental health, please read studies about warning signs of PTSD you need to know, and results showing old blood pressure drug may help treat PTSD.
For more information about health, please see recent studies about vegetarianism linked to higher risk of depression, and results showing Vitamin B6 could reduce anxiety and depression.
The study was conducted by Cecilia Hinojosa et al and published in the Journal of Psychiatric Research.
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