University of Missouri - Saint Louis

The Graduate School


An oral examination in defense of the dissertation for the degree

Doctor of Philosophy in Psychology

Leah Blain
M.A. in Psychology, May, 2009, University of Missouri-St. Louis
B.A. in Psychology, May, 2004,Vassar College

Motivational Interviewing as an Augmentation to Increase Effectiveness in Cognitive Processing Therapy for PTSD: An Initial Trial



Currently, even well-supported cognitive behavioral therapies to treat posttraumatic stress disorder (PTSD) suffer from consistent rates of dropout and non-response to treatment, which represent barriers to dissemination and effective treatment. Research in anxiety disorders, including an initial group-based study with veterans suffering from PTSD, suggests that Motivational Interviewing (MI) may be an effective intervention for addressing issues of ambivalence and increasing readiness to change, resulting in decreases in dropout and non-response. The present pilot study sought to assess the efficacy of augmenting Cognitive Processing Therapy (CPT) with 3 sessions of MI in a sample of female interpersonal assault survivors (N = 17). Within the MI study pilot sample, participants presented with a range in readiness to change (RTC), evidenced increases in RTC across the MI sessions (F = 3.48, p = .053), and demonstrated differential need for MI augmentation throughout the CPT sessions, as hypothesized. Moreover, no participants dropped out during the MI sessions, and participants noted that they found the MI sessions helpful and drew on the MI prep sessions to stay motivated during treatment. Contrary to hypotheses, MI did not significantly impact treatment expectations or fear of treatment; however, those that went on to complete treatment differed from those who dropped out of CPT in change over the course of MI (F = 8.39, p = .013). The pilot results were also compared to a concurrently conducted comparison CPT trial (N = 92) as well as to the broader PTSD outcomes literature. Comparison results indicate that MI did not substantially improve dropout rates (X2 = .49, p = .782) or treatment engagement measures (F = 1.24, p = .290), and that MI+CPT participants evidence similar symptom outcomes to the parallel trial (F = .84, p = .541). Similarly, MI study rates were at the high end for dropout and evidenced equivalent treatment outcomes, as compared to recent CPT trials. Interestingly, MI did not have a differential effect on readiness to change measures (F = 1.86, p = .093) as compared with the Hypnosis study conditions. Study limitations and clinical implications are considered.


Date: June 12, 2013

Time: 12:00p.m. to 2:00p.m.

Place: Center for Trauma Recovery, Conference Room


Defense of Dissertation Committee


Tara Galovski, Ph.D. (chair)

Kelly Maieritsch, Ph.D.


Zoƫ Peterson, Ph.D.

Matthew Taylor, Ph.D.