[1] Univ W Indies, Res Inst Trop Med, Epidemiol Res Unit, Kingston 7, Jamaica
[2] Purdue Univ, Dept Psychol Sci, W Lafayette, IN 47907 USA
[3] Univ W Indies, Caribbean Child Dev Ctr, Mona, Jamaica
[4] Univ Michigan, Ctr Human Growth & Dev, Ann Arbor, MI 48109 USA
[5] Univ Michigan, Dept Pediat & Communicable Dis, Ann Arbor, MI 48109 USA
[6] Columbia Univ, Div Child & Adolescent Psychiat, New York, NY USA
[7] Univ Calif Davis, Davis, CA 95616 USA
[8] UCL, Inst Child Hlth, Ctr Int Hlth & Dev, London, England