Is exposure necessary to treat PTSD?


Expert consensus, international treatment guidelines, and research evidence all indicate that trauma focussed psychological interventions (including Trauma Focussed Cognitive Behavioural Therapy and Eye Movement Desensitization and Reprocessing) are the most effective treatments for people experiencing Post Traumatic Stress Disorder (PTSD). There is also significant consensus in the literature that a key therapeutic ingredient of these treatments is exposure to trauma related memories or cues.

However, despite solid evidence for the efficacy of these treatments, there remain some issues with their delivery. As with many other psychological therapies, not all clients respond to treatment, with roughly a third not showing clinically significant change. Exposure based treatments can also involve both client and therapist discomfort, which can lead to treatment drop-out and lack of routine implementation in clinical practice.

There is therefore potential utility in exploring treatment mechanisms other than exposure to treat PTSD. Indeed, other emotional disorders have been found to have multiple treatment mechanisms; depression, for example, can be effectively treated using cognitive behavioural therapy, behavioural activation, interpersonal psychotherapy and SSRIs. If the same were to be true for PTSD, then this would open up further options for treating ‘non-responders’ or those who are unwilling to engage in trauma focussed work.

Given that PTSD frequently has a significant interpersonal component and that social support appears to foster recovery in PTSD, Markowitz and colleagues have been exploring the potential of interpersonal psychotherapy (IPT) as an alternative treatment for PTSD for several years. This RCT represents the culmination of that work to date.

Exposure based PTSD treatments involve exploring trauma-related memories or cues, which can be prohibitively difficult for some clients.

Exposure based PTSD treatments involve exploring trauma-related memories or cues, which can prove to be prohibitively difficult for some clients.


This study was a single blind randomised controlled trial with three treatment arms:

  1. Prolonged exposure (PE),
  2. Interpersonal psychotherapy (IPT) or
  3. Relaxation therapy (RT)

Participants (n=110) were recruited via advertisements.

Inclusion criteria included:

  • Age 18-65 years
  • A primary DSM-IV diagnosis of chronic PTSD
  • A Clinician administered PTSD scale (CAPS) score > 50 (indicating at least moderate PTSD)

Exclusion criteria included:

  • Psychotic disorders
  • Bipolar disorder
  • An unstable medical condition
  • Substance dependence
  • Active suicidal ideation
  • Antisocial, schizotypal, or schizoid personality disorder
  • Prior nonresponse to >8 weeks of a study therapy
  • Ongoing psychiatric treatment including pharmacotherapy

The primary outcomes were PTSD diagnosis and symptom severity, measured using the CAPS.

Secondary outcomes were:

  • Subjective PTSD symptoms (Post Traumatic Stress Scale Self-Report)
  • Social adjustment and functioning (the Social Adjustment Scale)
  • Quality of life (the Quality of Life Enjoyment and Satisfaction Questionnaire)
  • Interpersonal functioning (Inventory of Interpersonal Problems)
  • Self-exposure to trauma reminders (Self Initiated In Vivo Exposure Scale)

Data were analysed as intent to treat with longitudinal mixed effects models.


Prolonged exposure (n= 38)

PE was delivered over ten 90-minute sessions. As per the standard protocol for this treatment, participants were asked to narrate an increasingly detailed trauma narrative and to confront trauma reminders in order to habituate fear responses. Participants were required to listen to session tapes as homework.

Interpersonal psychotherapy (n = 40)

IPT was delivered over fourteen 50-minute sessions. The focus in IPT is not on the trauma itself, but on its interpersonal aftermath. The first half of treatment focussed on affective attunement and emotional recognition and expression in interpersonal situations. The remainder of sessions then focused on typical IPT problem areas such as role disputes and role transitions. No homework tasks were given.

Relaxation therapy (n = 32)

RT was highly scripted and involved progressive muscle and mental relaxation. Participants were required to listen to relaxation tapes as homework.

In order to standardise treatment duration to 14 weeks (as per the IPT protocol), PE and RT were delivered with 7 consecutive weekly sessions and then a further 3 sessions dispersed across the remaining 7 weeks.

Study therapists were psychologists and psychiatrists with expertise and primary allegiance in their therapy modality.


  • Participants were a highly traumatised, chronic group; 93% reported interpersonal trauma and 58.2% reported chronic trauma. There was a high degree of comorbidity, including nearly half of the sample meeting criteria for a personality disorder diagnosis.
  • Rates of response at 14 weeks (end of treatment), defined as an improvement of 30% in CAPS score, were:
    • 63% for IPT
    • 47% for prolonged exposure
    • 38% for relaxation therapy
    • This was not significantly different between groups.
  • CAPS outcomes for IPT and PE differed by only 5.5 points (not significant), therefore indicating that IPT was non-inferior to PE.
  • Treatment remission did not differ between groups.
  • Participants in the PE and IPT groups showed significantly greater improvement in self-reported PTSD symptoms compared with those in the RT group.
  • Patients in the PE group improved faster than those in the IPT group.
  • PE and IPT also showed significantly better results than RT in relation to quality of life, social functioning and interpersonal problems, and they did not differ significantly from each other in these areas.
  • Drop out rates were:
    • 15% in IPT
    • 29% in PE
    • 34% in RT
    • This was not significantly different between groups
    • Patients with comorbid major depression were 9 times more likely than non-depressed patients to drop out of PE therapy.
The response rates and drop out rates of the three treatments were not significantly different.

The response rates and drop out rates of the three treatments were not significantly different.


The authors concluded that:

As IPT emerged no more than minimally inferior to prolonged exposure on the primary outcome measure, had a statistically non significant but clinically meaningful higher response rate, and had a lower dropout rate among patients with comorbid major depression, the treatments appeared roughly equipotent. These findings contradict the widespread clinical belief in PTSD therapeutics that patients require cognitive-behavioral therapy or exposure to trauma reminders.

This RCT suggests that people with PTSD may benefit from an alternative to CBT or exposure.

This RCT suggests that people with PTSD may benefit from an alternative to CBT or exposure.


  • The therapists delivering each of the trial therapies reported primary allegiance to that treatment model, thus reducing any potential bias towards IPT from therapists affiliated with a research group that is strongly allied to this therapy.
  • The trial also provided convincing comparisons by effectively being able to compare IPT to both a ‘gold standard’ treatment (PE) and what might be considered to be a ‘placebo’ treatment (RT).


  • Whilst standardising the length of the treatment across groups was clearly important, stretching the PE and RT protocols to fit the timeframe of the IPT protocol meant that at the 14 week assessment point the IPT group would have been seeing a therapist weekly, whereas the other two groups would have had a period of much more sporadic contact. I wonder whether this may have biased outcomes in favour of IPT.
  • Participants were only eligible for the trial if they were non-medicated. Whilst this controls for the effects of medication, it also reduces the generalisability of the results to routine clinical situations, in which many people will have been prescribed medication.
  • I am also interested in the clinical profile of the sample. It appears that they are not necessarily representative of the overall PTSD population. A high proportion had interpersonal trauma which was chronic and a high proportion had co-morbid personality disorders. This raises questions for me regarding how these results can be generalised across diverse PTSD populations. I wonder whether the sample here are more representative of a complex-PTSD population, in which interpersonal difficulties are known to be particularly prominent and important in treatment. Indeed, a well evidenced treatment model in this group is the Skills Training in Affect and Interpersonal Regulation (STAIR) model in which treatment focusses on emotion regulation and interpersonal difficulties, prior to delivering exposure based treatments.


This is a promising study, which presents the potential of another efficacious treatment for PTSD. Having more choice regarding effective treatments would certainly be of benefit for survivors of trauma. However, I think that further research is needed regarding specific populations this treatment may or may not be indicated for.

Questions remain about how applicable these trial findings are to the general PTSD population.

Questions remain about how applicable these trial findings are to the general PTSD population.


Primary paper

Marowitz, JC, Petkova, E, Neria, Y, Van Meter, PE, Zhao, Y, Hembree, E, Lovell, K, Biyanova, T, Marshall, RD (2015) Is Exposure Necessary? A Randomized Clinical Trial of Interpersonal Psychotherapy for PTSD. American Journal of Psychiatry, 172 (5): 430-440.

Cheryl Ann Quigley /

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