Personality and Group Psychotherapy Outcome: The Lack of Influence of Traits From the Five-Factor Model

Although there is accumulating evidence of the importance of personality in predicting group psychotherapy outcomes, the extent to which Big Five personality traits predict group psychotherapy outcomes is debatable. Thus far, findings from individual treatment studies suggest Big Five traits have a marginal-to-small impact on the success of psychotherapy. Yet, results from the handful of group therapy studies on Big Five traits are equivocal. Moreover, extant research on Big Five traits and group treatment outcomes do not address potential dependencies in their data and, despite conducting multiple significance tests, neglect to correct for an inflated Type I error rate. Objective: We addressed these limitations through the largest, most methodologically rigorous investigation of the extent to which Big Five traits predict group treatment outcomes to date. Method: Recently discharged patients with mental health problems (N = 128; M (age) = 41.7, SD = 11.6) receiving short-term group therapy completed a measure of Big Five traits (NEO Personality Inventory-Revised) at pretreatment and measures of depression symptoms (Beck Depression Inventory) and anxiety symptoms (Beck Anxiety Inventory) at pretreatment, posttreatment, and 6-month follow-up. To address potential dependencies, we adopted a multilevel modeling strategy and, to address the multiple comparison problem, we used the Benjamini-Hochberg procedure. Results: None of the Big Five traits predicted smaller or greater reductions in depression or anxiety symptoms at posttreatment or 6-month follow-up. Conclusion: We found no evidence that the Big Five traits were associated with group psychotherapy outcome.