Amygdala activity predicts posttraumatic stress disorder

"This study introduces a new potential biomarker of PTSD, highlighting new roles for neuroimaging in PTSD research," said Dr. John Krystal, Editor of Biological Psychiatry. The identification of a PTSD biomarker has exciting implications for limiting or preventing symptoms of the disorder.

"The search for such early biological markers of poor recovery is very important, because it will allow us to find the people who are most at risk right after a trauma, and intervene early, before the onset of disorders such as PTSD or depression," said first author Dr. Jennifer Stevens, of Emory University.

In the study, Stevens and colleagues used functional magnetic resonance imaging to measure brain activity of 31 people approximately one month after a traumatic incident. The trauma was non-military related and included events such as a car accident or sexual assault. While the participants observed images of fearful faces (an index of threat), the researchers measured how the neural activity reacted in the amygdala and ACC, a brain region that regulates amygdala function, and how the activity changed over time with repeated viewing. Self-reported PTSD symptoms were assessed at 1, 3, 6, and 12 months after trauma.

People with a greater amygdala response to fearful faces had greater initial symptom severity, and were more likely to maintain PTSD symptoms over the following year. Additionally, those with a sharper drop in ventral ACC activity over repeated viewing of fearful images, called habituation, showed a poorer recovery trajectory. The findings suggest that amygdala reactivity and ventral ACC habituation to a threat predict the emergence of PTSD symptoms after trauma.

"The findings also suggest that an over-active amygdala may be one of the causes of PTSD, and that we should try to develop treatments that reduce amygdala reactivity," said Stevens. For example, the region could be targeted with interventions such as psychotherapy or pharmacological treatments that can be administered shortly after trauma occurs.