Active components and mechanisms of action of psychological interventions in bipolar disorder: A systematic literature review.

Objective: The efficacy of psychological interventions for bipolar disorder (BD) is well established, but much remains unknown about how change occurs. The primary objective of this exploratory study was to audit what is known about active components and mechanisms of action of psychological interventions for BD.

Method: We conducted a systematic review (PROSPERO CRD42022323276). Two independent reviewers screened references from four databases and extracted data from eligible studies.

Results: We included four component studies, six studies with mediation analyses and 26 studies presenting subjective experiences of how psychological interventions bring change. Ten mediators were examined across six studies, with only one putative mediator, medication adherence, tested in more than one study. Some initial support for mediation of varied outcomes by control over thoughts, positive non-verbal behaviour, self-esteem, post-trauma growth and medication adherence. Some preliminary support was found in two components, human support and IPT. Studies exploring participant experiences of therapeutic change enumerated a range of potential active components, mechanisms of action and contextual factors potentially warranting investigation in future research. However, the evidence base for active components and mechanisms of action in psychological interventions for BD is unsatisfactory. Findings were inconsistent, studies homogenous with significant methodological limitations and statistical approaches failed to meet quality criteria.

Conclusions: Preliminary identification of potential components and mechanisms via qualitative analyses and the insights emerging from this review will inform future research aimed at investigating how psychological interventions work in BD.