A Randomized Trial of Cognitive Therapy and Imaginal Exposure in the Treatment of Chronic Posttraumatic Stress Disorder

Reviewed by
Priscilla Schulz, LCSW

from an article of the same title by:
N. Tarrier, Hazel Pilgrim, Claire Sommerfield, Brian Faragher, Martina Reynolds, Elizabeth Graham, and Christine Barrowclough, University of Manchester

Journal of Consulting and Clinical Psychology, V. 67 (1), 13-18, 1999

What main question does this study address?
Is imaginal exposure or cognitive therapy more effective in relieving symptoms of posttraumatic stress disorder (PTSD) in patients with chronic PTSD? Numerous studies have evaluated the efficacy of these and other trauma treatment methods with different client populations. This study directly compares two approaches by eliminating overlapping components of each.How do the treatments differ?

In imaginal exposure the client repeatedly recounts trauma experiences over the course of several sessions until the emotions generated by the retelling habituate (lessen) over time. The client retells his/her experiences using the present tense as if the experience were happening all over again. In this study, discussion of the meaning of the traumatic event was not part of the imaginal exposure treatment to distinguish it from cognitive therapy.

In cognitive therapy clients discuss the meaning of trauma experiences and attributions following the event in the context of the their prior belief systems. Maladaptive thought patterns and dysfunctional ways of coping with emotions are identified and modified through the course of treatment.

In the normal course of clinical practice using cognitive therapy, discussion of the trauma itself is part of the treatment. Because such discussion is similar to imaginal exposure, this part of cognitive therapy was not included in the cognitive therapy protocol used for this study.

Is cognitive therapy or imaginal exposure superior in treating patients with chronic PTSD?
Both treatments worked equally well. Outcome measures showed a significant improvement in patients regardless of which treatment was used, cognitive therapy or imaginal exposure. More specifically,

    1. 50% of all study participants improved, 50% remained PTSD cases. At the six month follow-up 48% continued to be PTSD cases.
    2. 40% of study participants had returned to work by the six-month follow-up compared to only 15% of study participants who were able to work at pre-treatment.
    3. Average attendance to therapy was biweekly instead of weekly as planned by the researchers.
    4. A significantly greater number of patients receiving imaginal exposure worsened over treatment. However, by the six-month follow-up, this number had decreased; there was then no longer a significant difference between treatments on the numbers of patients who did and did not improve.
    5. Comparisons of patients who worsened during treatment with those who improved showed significant differences between the two groups. Compared to those who improved, those who worsened:
      • Had rated the treatment as not credible
      • Were rated by their therapist as poorly motivated
      • Missed significantly more therapy sessions
      • Had longer times between therapy sessions due to missed appointments
The circumstances characteristic of patients who worsened (i.e., missed appointments, longer time between appointments) led researchers to think that when patients do not fully cooperate with the treatment schedule of imaginal exposure, they can become sensitized rather than desensitized to trauma memories. This phenomenon could account for the increased PTSD symptoms of some patients who underwent imaginal exposure.

Is improvement in PTSD caused by paying attention to a patient's PTSD symptoms or is it the result of therapeutic treatment?
Pilot work conducted by the researchers found that for some PTSD patients, simply monitoring the patient's symptoms brought about improvements. To control for this effect and to ensure that improvements in PTSD during the study resulted from treatment, researchers included a monitoring phase prior to the treatment phase. Only those patients who remained PTSD cases after the monitoring phase were included in the treatment phase of the study.

What does this study tell us about the effectiveness of trauma treatments for patients with chronic PTSD?
Whereas patients in both treatment conditions showed improvements after treatment and at the six-month follow-up, many patients remained symptomatic. Researchers admit that neither therapy was sufficient alone to completely remediate chronic PTSD.

Researchers found that for patients in both therapies, keeping appointments was a problem resulting in longer duration of treatment (16 sessions over a 24 weeks instead of 16 weeks), longer time between sessions (biweekly instead of weekly) and a reduced number of sessions. Most patients reported that attending therapy was very stressful leading researchers to conclude that missed appointments represented PTSD avoidance.

What were the study's limitations?
The study does not explain criteria for considering participants as having completed treatment when some had "a reduced number of sessions." Attendance problems may have affected treatment outcomes, but comparisons between those participants who fully complied with treatment protocols with those who did not fully comply are not offered. Researchers add other limitations of the study:
    1. A wait-list or "no treatment" control was not part of the study
    2. The treatments used in the study were consistent with the principles of exposure and cognitive therapies, but they are not directly comparable to those used elsewhere.

Reviewed by Priscilla Schulz, September 1999
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