The effectiveness of non-pharmacological treatments for auditory verbal hallucinations in schizophrenia spectrum disorders: A systematic review and meta-analysis.

Abstract

Schizophrenia is a chronic severe mental illness affecting 24-million people globally, associated with a life expectancy 15 years shorter than the general population. Approximately 70% of people with schizophrenia experience auditory verbal hallucinations (AVHs), i.e. 'hearing voices'. Current treatment approaches remain unsuccessful in up to 30% of cases. This systematic review and meta-analysis evaluated randomised controlled trials (RCTs) of non-pharmacological treatments for AVHs in schizophrenia spectrum disorders, assessing emerging treatment effectiveness and identifying research gaps. A literature search was performed between 2013-2024 across five databases: PubMed, Embase, PsycINFO, Medline, and Web of Science. The meta-analysis included 45 studies based on predefined criteria and bias assessment. Effect sizes (Hedge's g) were calculated using a random effects model with 95% confidence intervals. The study followed PRISMA guidelines and was pre-registered (PROSPERO ID: CRD42024598615). Our sample included 2,314 patients and fourteen interventions. The overall mean effect size was -0.298 (95% CI, [-0.470, -0.126]), representing a medium, statistically significant effect. Subgroup analyses revealed medium, statistically significant effects for both AVATAR therapy and cognitive behavioural therapy (CBT). Conversely, repetitive transcranial magnetic stimulation (rTMS) and transcranial direct current stimulation (tDCS) showed small, non-significant effects. AVATAR therapy has the strongest evidence for treating AVHs, highlighting the need for large-scale RCTs and integration into treatment guidelines. CBT requires methodological standardisation. Acceptance and commitment therapy shows promise but needs further high-quality RCTs. Non-invasive brain stimulation techniques require additional trials before clinical implementation.