Mechanisms of change in acceptance and commitment therapy for primary headaches

Background: Despite the demonstrated effectiveness of behavioural headache interventions, it is not yet known which intervention processes account for treatment responses. Acceptance and commitment therapy (ACT), an emerging behavioural intervention for headaches, proposes psychological flexibility (PF) processes as the mechanisms via which intervention change occurs. This is the first study examining these processes of change variables on headache-related disability and quality of life (treatment outcome). Methods: Data originated from a Randomized Clinical Trial evaluating the efficacy of ACT for primary headaches. Ninety-four individuals with primary headaches (M = 43 y; 84% females; M headache frequency/month = 9.30) were randomized to either an ACT-based or a Wait-list control group (N = 47 in each). Participants completed questionnaires related to their headache experiences and PF processes at pre- (T1), post-treatment (T2), and 3-month follow-up (T3). Results: Following a bootstrapped cross product of coefficients approach, results demonstrated mediating effects of headache acceptance, cognitive defusion, avoidance of headache, and mindfulness in the ACT group compared to control on parameters of headache-related disability and quality of life at post and 3-month follow-ups. Conclusions: These findings demonstrate that changes in certain PF processes lower disability and improve quality of life in headache sufferers, supporting that ACT works via its proposed mechanisms of change. Interventions for headache management may be optimized if they target increases in headache acceptance, defusion from thoughts, and mindfulness. Significance: Psychological flexibility (PF) guides the ACT approach, an emerging behavioral headache intervention that focuses on optimizing head pain adjustment via flexible responses to pain. It targets at increasing daily functioning rather than preventing or controlling headache episodes. Pain acceptance, cognitive defusion, and mindfulness act as processes of functional change in ACT, lowering disability and increasing daily functioning and quality of life. These components can upgrade the established effectiveness of behavioral headache interventions with personalized, modularized therapeutic targets that can help headache sufferers re-establish optimal daily functioning even in fluctuating and persistent headache episodes