 The purpose of this study is to use a direct measure of brain volume and matter by means of MRI to determine if there is a differential effect between aripiprazole and risperidone on brain morphology in participants with first-episode psychosis. A secondary objective is to see if fasting metabolic indices measured in the blood i.e. glucose, insulin, total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, adiponectin and leptin are also correlated to changes in brain morphology or symptom severity as measured by neuropsychiatric assessments. 