[1] Harvard Univ, Sch Med, Dept Hlth Care Policy, Boston, MA 02115 USA
[2] Harvard Univ, Sch Med, Div Gen Pediat, Childrens Hosp Boston, Boston, MA 02115 USA
[3] Boston Univ, Sch Educ, Boston, MA 02215 USA
[4] NIMH, Div Dev Translat Res, Bethesda, MD 20892 USA
[5] NIMH, Div Intramural Res Programs, Bethesda, MD 20892 USA
[6] Duke Univ, Sch Med, Dept Psychiat & Behav Sci, Ctr Dev Epidemiol, Durham, NC USA