Date created: | Last Updated:

Category: Project

Description: Objective: The effectiveness of Acceptance and Commitment Therapy (ACT) for chronic pain is supported by numerous studies, yet little is known about its underlying mechanisms of change, especially for patients with complex mental comorbidity. The present investigation addressed this issue by examining associations of ACT-specific processes (pain acceptance, mindfulness, psychological flexibility) and clinical outcomes (pain intensity, somatic symptoms, physical health, mental health, depression, general anxiety). Subjects: Participants were 109 patients who attended an ACT-based interdisciplinary treatment program for chronic pain and comorbid mental disorders in a tertiary care psychiatric day treatment center. Methods: Pre- to post-treatment differences in processes and outcomes were examined with Wilcoxon signed-rank tests and effect size r. Associations between changes in processes and changes in outcomes were analyzed with correlation and multiple regression analyses. Results: Pre- to post-treatment effect sizes were mostly moderate to large (r between |.21| and |.62|). Associations between changes in processes and changes in outcomes were moderate to large for both, bivariate correlations (r between |.30| and |.54|) and shared variances accounting for all three processes combined (R² between .21 and .29). Conclusion: The present investigation suggests that changes in pain acceptance, mindfulness and psychological flexibility are meaningfully associated with changes in clinical outcomes. It provides evidence on particular process-outcome associations that had not been investigated before. The focus on complex mental comorbidity informs clinicians about a population of chronic pain patients that often has a severe course of illness and has seldom been studied.