[1] Univ Maryland, Sch Publ Hlth, Dept Epidemiol & Biostat, College Pk, MD 20742 USA
[2] Univ Calif Berkeley, Sch Publ Hlth, Dept Community Hlth, Berkeley, CA 94720 USA
[3] Univ Calif Berkeley, Sch Publ Hlth, Dept Human Dev & Epidemiol, Berkeley, CA 94720 USA
[4] Univ Calif San Francisco, Dept Psychiat, San Francisco, CA USA
[5] Univ Calif San Francisco, Dept Biochem & Biophys, San Francisco, CA 94143 USA
[6] Emory Univ, Sch Publ Hlth, Dept Behav Sci & Hlth Educ, Atlanta, GA USA