ACT with Pain : measurement, efficacy and mechanisms of Acceptance & Commitment Therapy

Abstract

Vast efforts have been made to improve the understanding and treatment of chronic pain as a highly complex and difficult-to-treat problem. Knowledge on psychosocial antecedents and consequences of chronic pain is now indispensable in research and practice. The overarching challenge for the field of chronic pain research is to find solutions to the magnitude of the societal problem of chronic pain, in light of the modest treatment gains for biomedical and psychological interventions. Acceptance & Commitment Therapy (ACT) is a relatively new form of Cognitive Behavioral Therapy (CBT) that could possibly help to dissolve this challenge. The overarching goal of ACT is to attain psychological flexibility, the capacity to act effectively in accordance with intrinsically motivating values and goals in the presence of pain and associated cognitions and emotions. In doing so, ACT applies mindfulness and acceptance processes, combined with values identification and behaviour change processes. Although a growing range of studies underscores the efficacy of ACT for chronic pain, the framework needs further examination. This thesis explores several research questions - inspired by proposed venues for future psychosocial chronic pain research - regarding the measurement, efficacy and working mechanisms of ACT. Among others, the thesis shows that a range of questionnaires with good psychometric properties are available to measure the six therapeutic processes of ACT. These include the Psychological Inflexibility in Pain Scale (PIPS) and the newly developed Engaged Living Scale (ELS). Outcomes of a large, thee-armed Randomized Controlled Trial (RCT) on the efficacy of a web-based self-help, ACT-based program (‘Living with Pain’) reveal that web-based ACT may be effective in improving (a.o.) pain interference in daily life. However, these effects are mainly present for those participants who adhere to the web-based intervention as intended, and who already experience mental resilience resources in the form of psychological well-being at baseline. With regard to the exploration of mechanisms of change, this thesis to a large extent confirms the premises of ACT’s theoretical psychological flexibility model both between (during the RCT) and within (during n-of-1 studies) persons. Finally, this thesis describes the successful implementation of ACT into Dutch chronic pain rehabilitation.