EFFICACY OF HIGH-DEFINITION TRANSCRANIAL DIRECT CURRENT STIMULATION IN NEGATIVE SYMPTOMS OF SCHIZOPHRENIA AS MEASURED BY PROTON MAGNETIC RESONANCE SPECTROSCOPY – A RANDOMISED SHAM CONTROLLED STUDY

BACKGROUND: In schizophrenia, negative symptoms are often resistant to treatment. Transcranial Direct Current Stimulation (tDCS) to dorsolateral prefrontal cortex (DLPFC) has been tried as an add-on treatment for negative symptoms. High-Definition tDCS (HD-tDCS), an optimized form of tDCS, ensures focalized neuromodulation and delivery of higher current densities. Anodal tDCS has been found to increase N-Acetyl Aspartate (NAA) levels in healthy volunteers and studies have found a relationship between reduced NAA concentration in frontal cortex and severity of negative symptoms. AIM: We aimed to evaluate the efficacy of HD-tDCS over left DLPFC for negative symptoms in schizophrenia and associated changes in NAA levels. METHODS: 36 patients of schizophrenia with negative symptoms, were enrolled for study. Participants in active group received 10 sessions of HD-tDCS at 2mA for 20min twice daily over 5 days. Magnetic Resonance Spectroscopy was done at baseline, after 2 sessions of HD-tDCS and 6 weeks. Negative symptoms were assessed with SANS and PANSS at baseline, 2 and 6 weeks. RESULTS: Improvement in negative symptoms in active group was statistically significant at 0.05 (p-value) as compared to sham group at 2 weeks. During 6 weeks follow-up, initial reduction in negative symptoms was maintained but no further improvement was noted. There was no significant difference between NAA levels and treatment group over time but there was significant correlation between changes in NAA levels and changes in negative symptoms. CONCLUSION: HD-tDCS may lead to improvement in negative symptoms and through neuroplastic effects, may alter NAA levels and exert its therapeutic benefits.