RESUMO
OBJECTIVE: Taurine is an inhibitory neuromodulatory amino acid in the central nervous system that activates the GABA- and glycine-insensitive chloride channel and inhibits the N-methyl-D-aspartate receptor. It also functions as a neuroprotective agent and has a role in neural development and neurogenesis. The aim of this study was to determine the efficacy of adjunctive taurine in improving symptomatology and cognition among patients with a DSM-IV first-episode psychotic disorder. METHODS: 121 patients with first-episode psychosis, aged 18-25 years, attending early intervention services consented to participate in this randomized, double-blind, placebo-controlled trial conducted from January 2007 to May 2009. Patients taking low-dose antipsychotic medication were randomly assigned to receive once-daily taurine 4 g or placebo for 12 weeks. The coprimary outcomes were change in symptomatology (measured by the Brief Psychiatric Rating Scale [BPRS] total score) and change in cognition (measured by the Measurement and Treatment Research to Improve Cognition in Schizophrenia [MATRICS] Consensus Cognitive Battery composite score) at 12 weeks. Secondary outcomes included tolerability and safety and additional clinical and functioning measures. RESULTS: 86 participants (n = 47 taurine; n = 39 placebo) were included in the final analysis. Taurine significantly improved symptomatology measured by the BPRS total score (95% CI, 1.8-8.5; P = .004) and psychotic subscale (95% CI, 0.1-1.5; P = .026) compared to placebo. Additionally, improvements were observed in the Calgary Depression Scale for Schizophrenia (95% CI, 0.1-3.0; P = .047) and Global Assessment of Functioning (95% CI, 0.3-8.8; P = .04) scores. There was no group difference in composite cognitive score (95% CI, -1.7 to 1.0; P = .582). A significant group difference was found on one safety and tolerability item (psychic item 2, asthenia/lassitude/increased fatigability) of the Udvalg for Kliniske Undersogelser, with the taurine group showing a more favorable outcome (P = .006). CONCLUSIONS: Adjunctive taurine did not improve cognition, but it appears to improve psychopathology in patients with first-episode psychosis. The use of taurine warrants further investigation in larger randomized studies, particularly early in the course of psychosis. TRIAL REGISTRATION: ClinicalTrials.gov identifier: NCT00420823.