The primary hypothesis is that compared to placebo, 10g of daily creatine monohydrate for eight weeks will be associated with significant increases in frontal lobe phosphocreatine and beta-nucleoside triphosphate (β-NTP) concentrations. A secondary hypothesis is that decreased depressive symptoms measured with the Children's Depression Rating Scale-Revised (CDRS-R) and Montgomery-Asberg Depression Rating Scale (MADRS) will be reciprocally correlated with increased β-NTP concentrations.