Prolonged exposure—which helps patients confront trauma memories and real-life situations that provoke symptoms—is known to be an effective treatment for PTSD, but many patients fail to respond to this therapy. Senior author Amit Etkin, M.D., Ph.D., of Stanford University School of Medicine and colleagues used functional MRI (fMRI) to examine brain activity in 66 patients with PTSD before prolonged exposure to see if there were functional differences between the brains of patients who responded to prolonged exposure therapy and those who did not.
The patients underwent fMRI while resting and while carrying out tasks meant to elicit emotional response and regulation when presented with a series of happy, fearful, or neutral facial images and negative or neutral photographs. The patients were then randomly assigned to immediate prolonged exposure treatment (nine to 12 90-minute prolonged exposure sessions held once or twice a week) or a waiting-list condition. Four weeks after the final treatment session or comparable waiting period, all participants completed a posttreatment clinical assessment.
Patients who received prolonged exposure therapy demonstrated a greater reduction in PTSD symptom scores than those assigned to the waiting list. Those with greater baseline dorsal prefrontal activation and less left amygdala activation during emotion reactivity tests showed larger reductions in symptom scores after treatment, the authors reported. Similarly, individuals with greater baseline ventromedial prefrontal/ventral striatal activation during implicit regulation of emotional conflict demonstrated larger symptom reductions after treatment.
According to Etkin and colleagues, the findings suggest that “an individual’s capacity to benefit from exposure therapy is gated by [the] degree of spontaneous prefrontal control over amygdalar threat detection signals during incidental processing of a fear-conveying stimulus and the brain’s capacity to reduce interference from an emotional cue in the environment.”
“This study provides a solid footing for understanding mechanisms so we can start working toward matching people to the treatment most likely to work for them and develop novel therapeutics for directly targeting brain therapy,” said Etkin. “By grounding psychotherapy in brain mechanisms, we can also hopefully decrease stigma, an invisible barrier to care that is so prevalent in psychiatric disorders and prevents people from getting the care that would benefit them.”
In an accompanying paper in AJP, Etkin and colleagues describe how imaging also revealed changes in the frontopolar cortex (the front-most portion of the prefrontal cortex) of PTSD patients who received prolonged exposure.
For related information, see the Psychiatric News article “Brain Scans May Indicate Optimal Treatment for Depression.”