The relationship between psychosis and psychological flexibility and other acceptance and commitment therapy processes: a systematic review and meta-analysis

Abstract

Introduction: The psychological inflexibility model proposes several transdiagnostic processes maintaining psychological distress and is one of the models forming the basis of Acceptance and Commitment Therapy (ACT). ACT has been recently used as an intervention for psychosis but prior to the present review and meta-analysis (PROSPERO ID: CRD42022369048) the relationship between psychological inflexibility and other ACT processes in the context of psychosis or psychosis-like symptoms has not been investigated. Method: A Literature search of PsychINFO, Medline, PsychArticles, Web of Science and Embase was conducted, and methodological quality assessed. 655 titles were screened and were included if they explored the relationship between psychological inflexibility (experiential avoidance, cognitive fusion, values clarity, committed action) and psychosis or psychosis-like symptoms in the general population. Results: A total of 32 studies were included in this review. Most studies were cross sectional and rated moderate in their methodological quality. Meta-analyses revealed a large effect of psychological inflexibility on paranoia, medium effect on delusions, small effect on auditory hallucinations. A medium effect of cognitive fusion on paranoia was found and medium effect size when comparing group differences (psychosis vs controls) in psychological flexibility. Additional findings (mostly mediation and moderation effects) not included in the meta-analyses are reported. Discussion: The overall evidence suggests that there is a significant relationship between psychological flexibility and psychotic symptoms, particularly paranoia. This provides evidence supporting the use of acceptance-based interventions in the context of psychosis. Limitations and future directions are discussed.

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ORCID for James Pittman: orcid.org/0009-0008-3195-1649

ORCID for Thomas Richardson: orcid.org/0000-0002-5357-4281

ORCID for Emma Palmer-Cooper: orcid.org/0000-0002-5416-1518

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