Role of Novel Dietary Supplement N-acetyl Cysteine in Treating Negative Symptoms in Schizophrenia: A 6-Month Follow-up Study

BACKGROUND: Abnormal metabolism of dopamine and glutamate in schizophrenia induces oxidative stress that is exacerbated by brain glutathione (GSH) deficiency. N-acetyl cysteine (NAC) increases brain GSH levels and is being used as an adjunctive agent in patients with schizophrenia. This open-label exploratory study in a naturalistic setting was conceived to examine the efficacy of NAC augmentation in treating negative syndrome in schizophrenia. AIMS: To examine the efficacy of add-on NAC (1200 mg) in treating negative symptoms measured using Scale for the Assessment of Negative Symptoms (SANS) and clinical global impression (CGI) at baseline and 24 weeks. SUBJECTS AND METHODS: In a 24-week feasibility study with open-label design, thirty patients with the International Classification of Diseases-Tenth Edition diagnosis of schizophrenia were recruited. Eligible patients were required to have been treated with stable dose of clozapine or amisulpride for negative symptoms for a minimum period of 8 weeks were selected for the study. The subjects were assigned to receive NAC (1.2 g/day) as an add-on treatment. Severity of negative symptoms was measured using SANS and CGI-severity at baseline and improvement with NAC measured using CGI-improvement at 24 weeks. Serum interleukin-6 was assessed before NAC initiation at baseline. RESULTS: NAC augmentation showed a significantly greater improvement in negative symptoms on total SANS and CGI scores at 24 weeks. CONCLUSIONS: NAC may be effective as an adjunct for the treatment of negative symptoms in schizophrenia.