Shorter Imaginal Exposure Sessions as Effective as Longer Exposure for PTSD

Shorter Imaginal Exposure Sessions as Effective as Longer Exposure for PTSD

Prolonged exposure (PE) is an evidence-based cognitive behavioral treatment that uses imaginal and in vivo exposure in the treatment of PTSD. Imaginal exposure involves the client recounting a core traumatic event in great detail repeatedly in session, and then listening to an audio recording of the exposure daily between sessions. In additional to imaginal work, clients engage in in vivo (Latin for “in life”) exposure to trauma-related triggers. Exposure is done until the client habituates to the trauma-related similar, and/or until PTSD symptoms are largely resolved, according to the PE model.

For those unfamiliar with exposure therapy, you can read more about other blog posts I’ve written on exposure.

Standard PE sessions are too long for how most therapists now practice

The research supporting PE is impressive, and I’ve always been impressed with the relative simplicity of its protocol. However, one concern I’ve had about the treatment protocol is that sessions are 90 minutes long, which is nearly impossible to have covered by insurance nowadays. When medical billing codes were revised in 2013, the code for a 90 minute session was cut, and 60 minutes became the longest standard session for which a therapist could bill. This change made PE out-of-step with the practice limitations of many therapists in the US.

To their credit, PE researchers responded to this concern in a recent study (Nacasch et al., 2015). This study is an improvement of a similar study (van Minnen & Foa, 2006) from several years ago.

The study

In the most recent study, 39 veterans were randomly assigned to 10-15 sessions of PE at either 90-minute with 40 minutes of imaginal exposure each session, or 60 minutes with 20 minutes of imaginal exposure each session.

What did they find?

  • Participants in the 60-minute sessions improved just as much as those in 90-minute sessions. There was no difference in outcome between the 2 groups at treatment completion.
  • Although participants in the 90-minutes sessions exhibited greater habituation to trauma-related stimuli, this didn’t impact the overall outcome for either group. I interpreted this as further evidence that, contrast to the emotional processing theory underlying PE,  habituation is a poor marker of improvement in exposure. The authors defend between-session habituation to some degree but admit that it does not seem to be a necessary condition for improvement in PTSD.
  • Very interestingly, even though participants in the 90-minute session condition were receiving twice as much therapy, they did not improve any more rapidly than those in the 60-minute session condition. Both groups completed treatment in the same number of sessions. In this instance, more is not necessarily better.

Summary

This is an extremely important study in that it provides evidence that—for prolonged exposure, at least—not only do people show as much improvement in 60-minute sessions as 90-minute sessions, that 20 minutes of imaginal exposure is no less effective than 40 minutes per session.

Shorter sessions and shorter exposure times can reduce the burden (e.g., time; money) for clients, and it makes it more feasible to offer evidence-based treatments such as PE in settings where 90-minute sessions are not covered.

My hope is that the main researcher and PE core originator, Dr. Edna Foa, does a similar study with her OCD exposure protocol, too, which also relies on 90-120 minute sessions!

If you want to read the full article yourself, the published version is behind a pay wall. However, one of the authors made the “in press” version available here.

Brian Thompson Ph.D.

Author: Brian Thompson Ph.D.

Brian is a licensed psychologist and Director of the Portland Psychotherapy Anxiety Clinic. His specialties include generalized anxiety, OCD, hair pulling, and skin picking.

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