The use of process measures in studies investigating effects of psychotherapy for depressive symptoms following acquired brain injury: A scoping review

Persons with acquired brain injury (ABI) often experience mood problems like depression. While psychotherapy is widely accepted for managing depression in populations without ABI, its effectiveness for post-ABI depression is uncertain. The working mechanisms of psychotherapy in persons with ABI may differ from idiopathic depression. This scoping review aimed to identify studies on psychotherapeutic interventions for post-ABI depression, assess the use of process measures (instruments measuring the mechanisms of psychotherapy), and report effects on both process and primary outcome measures. In the 47 included studies, Cognitive Behavioural Therapy, Problem Solving Therapy, and Third-Wave Therapies were most frequently investigated. Results indicated that less than half of the studies implemented a process measure. Studies into Third-Wave Therapies most frequently implemented process measures. Around half of the studies found significant time or interaction effects on the process measure, while not necessarily finding effects on outcome measures for depression. Moreover, the review could not identify a specific type of intervention effective in improving depressive symptoms and the underlying process. Our findings emphasize that it is still unclear which psychotherapy works for whom, and how. To enhance understanding of effective interventions for post-ABI depression, it is crucial to incorporate process measures in future intervention studies.