 Phase 2 will run concurrently with Phase 1, but will extend to 5 years, in order to give all participants an opportunity to continue from one phase to the next if they meet entry criteria. Participants in Phase 2 will attend four study visits over the course of 3 months: one at the beginning of the phase and one after each month of the study. After the first study visit, participants will be given folic acid to take daily for the 3 months. At each study visit, participants will be asked about thoughts, illness, functioning, diet, medication side effects, recent medication history, smoking history, alcohol intake, and exercise habits. On the first and last visits, participants will undergo additional tests of genetics, blood hormone levels, and blood vessel functioning, and additional measurements will be made of height, weight, vital signs, and body size. The Phase 2 study is now inactive. 