Metacognitive Training for Negative Symptoms (MCT-Minus) in schizophrenia: study protocol for a pragmatic randomized controlled trial.

BACKGROUND: Negative symptoms are experienced by up to 60% of the individuals with schizophrenia and represent a stronger indicator of current and future functioning than positive symptoms. These symptoms respond poorly to pharmacological and existing psychosocial interventions, highlighting the need for targeted treatments. Previous research suggests that defeatist performance beliefs, combined with metacognitive deficits, may contribute to negative symptoms. A recent pilot study, adapting the cognitive intervention metacognitive training (MCT) to address negative symptoms, found symptom reduction, primarily due to improved reflective functioning and reduced perceived stigma. The current study aims to further assess the efficacy of this intervention and to explore potential mechanisms of change in negative symptoms. METHODS: Ninety participants aged 18 and older with a psychotic disorder will be recruited from psychiatric care settings in Sweden. Participants will be randomly assigned to either the intervention group (MCT-Minus) or a control group receiving supportive counselling (SC). Data will be collected at baseline, post-intervention, and at 12-week and 12-month follow-ups. Magnetic resonance imaging (MRI) will be performed at baseline and post-intervention. Exit interviews will be held after completing the intervention. The primary outcome is change in negative symptom, measured by the Clinical Assessment Interview for Negative Symptoms (CAINS), across all time points. Repeated measures ANCOVA will be used to evaluate primary outcomes. Additional analyses will address changes in positive symptoms and potential mechanisms of change, including metacognition and internalized stigma. Qualitative data from exit interviews will be analyzed using reflexive thematic analysis. DISCUSSION: This study is designed to evaluate the efficacy of MCT-Minus compared to supportive counselling. Given the limited treatment options for negative symptoms in schizophrenia, the findings may have important clinical implications. TRIAL REGISTRATION: This study was registered on the 6th of November 2023 on Clinical Trials with the trial registration number NCT06127004. Statistical analyses will be preregistered on the Open Science Framework.