 Participation in this study will involve two phases. The first phase will involve recruitment, screening, and testing of participants taking antipsychotics and will last 4 years. During this phase, participants will attend one study visit in which they will undergo a screening for metabolic syndrome and have the following measured: endothelial functioning, body size, diet, physical activity, medication history, and genetic makeup. Participants who have metabolic syndrome will be invited to participate in Phase 2. 