Concomitant Medications: Participants in the study will be allowed to continue on their medication regimen that they were taking prior to the trial. This will allow the results to be more generalizable. Patients must be stabilized on a single second generation antipsychotic, excluding clozapine, at an unchanged dose for at least 4 weeks prior to randomization. All participants must be on a stable dose of all other psychotropic medications for at least 4 weeks prior to randomization. No medication changes or changes in dose will be permitted during the study period.