Zoellner, Lori AJun, Janie J2016-03-112016-03-112015-12Jun_washington_0250E_15233.pdfhttp://hdl.handle.net/1773/35305Thesis (Ph.D.)--University of Washington, 2015-12To date, there is a dearth of empirical evidence within the "black box" between pre- and post-treatment to fully understand how and why our interventions work. It is essential to take a process-oriented approach with research to elucidate trajectories and mechanisms of individual change in PTSD treatment. Sudden gains, defined as rapid, large symptom improvements during between-session intervals, have been investigated across different samples and interventions and have consistently been associated with better treatment outcome. Utilizing sudden gains as markers of critical points of transition, the in-session therapist-patient interactions prior to the gains were examined using a process-oriented, detailed coding system for potential processes of change associated with sudden gains. This was the first study to systematically examine in-session therapy content for potential mechanisms triggering sudden gains in PTSD treatment. Pre-treatment trait-like factors of distress tolerance and neuroticism and more proximal factors of fear activation, between-session, and within-session distress reductions were also examined as potential predictors of sudden gains. When examining the pre-gain sessions, patients who experienced sudden gains expressed more positive hope and had more cognitive-emotional processing than those who did not exhibit sudden gains, suggesting these are key elements for discontinuous change. Sudden gains occurred similarly in both PE only and PE combined with sertraline treatment. However, when examining pre-gain in-session content, patients receiving PE only had more cognitive-emotional processing than patients receiving PE combined with sertraline, highlighting potential different mechanisms between the two treatments. Finally, distress tolerance-related absorption predicted the occurrence of sudden gains, suggesting that individuals who pay more attention to negative emotional states and thoughts are more likely to experience a sudden gain. However, no other predictors of neuroticism, fear activation, between-session distress reduction, and within-session distress reduction were associated with sudden gains. All together, the findings of this study bring a better understanding of the sudden gain phenomenon and elucidate what are the key elements of change in PTSD treatment. By enhancing these key elements of change, the efficacy and efficiency of the interventions can be maximized and will allow the tailoring of interventions to specific patients based on his or her needs and strengths of achieving change.application/pdfen-USClinical psychologypsychologyThesis