Processes of change in psychological flexibility in an interdisciplinary group-based treatment for chronic pain based on Acceptance and Commitment Therapy.

There are now numerous studies of Acceptance and Commitment Therapy (ACT) for chronic pain. These studies provide growing support for the efficacy and effectiveness of ACT in this context as well as for the role of ACT-specific therapeutic processes, particularly those underlying psychological flexibility. The purpose of the present study was to continue to build on this work with a broader focus on these processes, including acceptance of pain, general psychological acceptance, mindfulness, and values-based action. Participants included 168 patients who completed an ACT-based treatment for chronic pain and a three-month follow-up. Following treatment and at follow-up, participants reported significantly reduced levels of depression, pain-related anxiety, physical and psychosocial disability, medical visits, and pain intensity in comparison to the start of treatment. They also showed significant increases in each of the processes of psychological flexibility. Most uncontrolled effect sizes were medium or large at the follow-up. In correlation analyses changes in the four processes measures generally were significantly related to changes in the measures of depression, anxiety, and disability. In regression analyses the combined processes were related to changes in outcomes above and beyond change in pain intensity. Although in some ways preliminary, these results specifically support the unique role of general psychological acceptance in relation to improvements achieved by treatment participants. The current study clarifies potential processes of change in treatment for chronic pain, particularly those aiming to enhance psychological flexibility.