Category: Treatment - ACT
Evaluating for whom and under what conditions self-help treatments work is an important component of anxiety disorder treatment development. This type of work can help clarify whether cognitive and behavioral treatments have similar effects across individual differences and identify important variables that moderate the impact of such interventions. Yet, research regarding moderators and correlates of change of self-help interventions is sparse. The current project evaluated moderators of outcome in an international, randomized wait-list controlled trial assessing the effectiveness of Acceptance and Commitment Therapy (ACT) bibliotherapy for anxiety difficulties in a relatively naturalistic self-help context.
Participants (N = 503) from 25 countries were randomized to an immediate workbook (n = 256) or wait-list condition (n = 247). Assessments at pre-treatment, 12 weeks, 6 months, and 9 months evaluated anxiety disorder symptoms (assessed using the Beck Anxiety Inventory) and quality of life (assessed using the Quality of Life Inventory). Participants in the wait-list arm crossed over to the workbook following the 12-week assessment.
Mixed model analyses evaluated the impact of treatment condition and a variety of baseline variables (e.g., psychological flexibility as assessed by the Acceptance and Action Questionnaire; anxiety sensitivity as assessed by the Anxiety Sensitivity Index; and demographic variables such as country, age, and ethnicity) on change over time in outcomes. Analyses also evaluated the relation between change in outcome variables and the degree to which participants reported that they applied the workbook material to their lives.
First, mixed model results showed that the ACT workbook produced improvement in anxiety symptoms (p < .001) and quality of life (p < .001), and these improvements were maintained at follow-ups. Second, moderation findings indicated treatment benefit generalized across most individual differences, such as country, ethnicity, and sex (ps > .09). Third, several key variables moderated the impact of the treatment. For example, the self-help intervention produced greater reductions in anxiety symptoms for people with greater baseline anxiety sensitivity (p = .021). Moreover, people who applied the workbook material to their lives by practicing exercises and using material learned in the workbook experienced larger improvements in both anxiety symptoms (p = .044) and quality of life (p = .043).
Collectively, results indicate ACT self-help for anxiety disorders might be effective in an international population and across a variety of individual differences and might also be more effective for people with greater baseline distress and for individuals who actively apply self-help material.