The effect of a reduction in irrational beliefs on Posttraumatic Stress Disorder (PTSD), depression, and anxiety symptoms in a group treatment for post-9/11 Veterans.

Previous research has indicated that a Rational Emotive Behavior Therapy (REBT)-Informed Group focused on changing irrational beliefs to address comorbid depression and anxiety (as well as anger and guilt) in a combat Veteran population diagnosed with Posttraumatic Stress Disorder (PTSD) demonstrated significant reductions in depression and PTSD symptoms at posttreatment. However, mechanisms of change associated with improvement have not been evaluated. REBT theory suggests that a decline in irrational beliefs predicts a decrease in PTSD, depression, and anxiety symptoms. This study aimed to test this tenet of REBT theory in a naturalistic treatment setting. Participants ( = 86) were post-9/11 combat Veterans, engaged in the REBT-Informed Group between October 2016 and February 2020. Results of hierarchical multiple regression analyses indicated that a reduction in irrational beliefs predicted notable decreases in PTSD, depression, and anxiety symptoms controlling for several covariates. This study extends previous research demonstrating the success of the REBT-Informed Group with combat Veterans and gives support to REBT theory regarding the effect of a decline in irrational beliefs. Future directions include replication of findings with Veterans who experienced military sexual trauma (MST), pre-9/11 Veterans, those at other military or Veterans Affairs (VA) medical centers, and civilians to determine generalizability.