An Investigation of the Effect and Processes of Group-based Acceptance and Commitment Therapy Preceded by Attentional Bias Modification in Secondary Prevention of Depression

Abstract

Depression is a serious disorder with a high prevalence and recurrence rate. There is a need for preventive treatment, but there are limited treatment options available. This thesis is based on a Norwegian multisite clinical study, investigating the effectiveness of an eight-week group-based Acceptance and Commitment Therapy (ACT) in treating residual symptoms of depression over 12 months. Furthermore, we examined if two weeks of experimental attentional bias modification (ABM) would provide an add-on effect. We also explored the role of psychological flexibility in reducing depressive symptoms, as measured by the Acceptance and Action Questionnaire (AAQ-II). Paper 1 demonstrated that group-based ACT is an effective treatment in decreasing residual symptoms of depression. ABM did not increase this reduction. Paper 2 found good psychometric properties of the Norwegian translated version of AAQ-II. Finally, paper 3 showed that psychological flexibility mediated changes in the improvement of depressive symptoms and positive mental health. In accordance with the model of ACT, most of the subprocesses were found to contribute to changes in psychological flexibility.