Transcranial Direct Current Stimulation for Treatment of Auditory Hallucination: A Systematic Review of Clinical Efficacy

Background and Objective: Transcranial direct current stimulation (tDCS) is a safe and cost-effective stimulation technique that has drawn great attention as a potential therapeutic modality for auditory hallucination (AH). This review aims to bring together the evidence from randomized clinical trials (RCTs) on the effectiveness of tDCS for the treatment of AH in schizophrenia. Method: Eligible articles were identified through a comprehensive search of the following electronic databases: PsycINFO, PubMed/MEDLINE, EMBASE, CINAHL, Web of Science, Cochrane Library, and Scopus. PRISMA protocol was used as a guide and totally 7 randomized clinical trials (RCTs) articles were assessed as suitable and included in the review. Results: Seven RCTs that evaluated the effects of tDCS on the severity of AHs in schizophrenic patients were included in this review. Analysis of the outcome measures of these studies pointed toward incongruence in the information with regard to the therapeutic use of tDCS in reducing the severity of auditory hallucinations in schizophrenia. Three RCTs reported a therapeutic benefit, manifested by reductions in severity and frequency of auditory verbal hallucinations in schizophrenic patients. Conclusion: The findings imply that tDCS has shown promising results in reducing the severity of auditory hallucinations in schizophrenic patients, although in some studies, its effect was negligible.