10. Patients who, by history, have received treatment with Risperdal or another neuroleptic (including olanzapine or quetiapine) within three months of baseline evaluation. Patients who have received a depot antipsychotic within one treatment cycle prior to screening. Patients who have taken an antidepressant, or lithium within 4 weeks of the trial, 6 weeks for fluoxetine. Patients who have taken any psychotropic medication within 1 week of the trial. Patients who require concomitant medications during the trial.