[1] Univ Bristol, Populat Hlth Sci, Oakfield House, Bristol BS8 2BN, Avon, England
[2] Univ Fed Pelotas, Postgrad Program Epidemiol, Pelotas, Brazil
[3] Kings Coll London, Inst Psychiat Psychol & Neurosci, London, England
[4] Virginia Commonwealth Univ, Virginia Inst Psychiat & Behav Genet, Richmond, VA 23284 USA