 Schizophrenia SZ is a highly debilitating neuropsychiatric disorder of young adulthood onset and a leading cause of disability worldwide. While treatments delivered at early stages of the disorder may be effective at reducing psychosis or altering the course of the disease, there are currently no biomarkers capable of identifying subjects in early stages of SZ who are likely to respond to treatment and would be good candidates for available proactive, symptomatic or future disease-modifying treatments; or those who would not respond and can be spared unnecessary medication exposure. The lack of these vitally important biomarkers provides a compelling rationale for the present multidisciplinary research project, which aims to develop and validate highly promising noninvasive and objective proton magnetic resonance spectroscopy 1H MRS-based biomarkers for monitoring treatment response in early stages of SZ. In support of the viability of this overall objective is a large body of data, reported by the applicants and others, that show a that levels of glutamate Glu and - aminobutyric acid GABA - respectively, the major excitatory and inhibitory amino acid neurotransmitter systems - are abnormally elevated in medication-naïve and unmedicated first episode and chronic SZ patients; b that the effect of treatment with antipsychotic medications in these populations may be to lower or normalize brain levels of both Glu and GABA. To investigate the potential of these in vivo brain Glu and GABA abnormalities to serve as biomarkers of treatment response in early-stage SZ, the applicants propose to use 1H MRS to measure Glu and GABA levels in the largest cohort of medication-free SZ subjects to date, at baseline and following 4 weeks of antipsychotic treatment. 