Some participants in this open-label study will be randomly assigned to receive quetiapine, olanzapine, or risperidone. Participants who are not randomly assigned to a medication will still receive one of the three medications, based on the decision of their physician. Initial evaluations will be conducted to collect demographic information, as well as medical, psychiatric, and pharmacologic histories. Dosing will be determined by each participant's psychiatrist. All participants will be followed for approximately 5 years. They will report to the study site for outcome assessments at baseline, Months 1 and 3, and every 3 months for the remainder of the study.