Do metacognitive therapies for schizophrenia-spectrum disorders work? A meta-analytic investigation

Recent reviews and meta-analyses of metacognitive therapy for schizophrenia-spectrum disorder (SSD) have included uncontrolled studies, single-session interventions, and/or analyses limited to a single form of metacognitive therapy. We sought to evaluate the efficacy of metacognitive therapies more broadly based on controlled trials (CT) of sustained treatments. We conducted a pre-registered meta-analysis of controlled trials that investigated the effects of meta-cognitive therapies on primary positive symptom outcomes, and secondary symptom, function and/or insight measures. Electronic databases were searched up to March 2022 using variants of the keywords, 'metacognitive therapy', 'schizophrenia', and 'controlled trial'. Studies were identified and screened according to PRISMA guidelines. Outcomes were assessed with random effects models and sample, intervention, and study quality indices were investigated as potential moderators. Our search identified 44 unique CTs with usable data from 2423 participants. Data were extracted by four investigators with reliability >98%. Results revealed that metacognitive therapies produced significant small-to-moderate effects on delusions (g = 0.32), positive symptoms (g = 0.30) and psychosocial function (g = 0.31), and significant, small effects on cognitive bias (g = 0.25), negative symptoms (g = 0.24), clinical insight (g = 0.29), and social cognition (g = 0.27). Findings were robust in the face of sample differences in age, education, gender, antipsychotic dosage, and duration of illness. Except for social cognition and negative symptoms, effects were evident even in the most rigorous study designs. Thus, results suggest that metacognitive therapies for SSD benefit people, and these benefits transfer to function and illness insight. Future research should modify existing treatments to increase the magnitude of treatment benefits.