[1] Nottinghamshire Healthcare NHS Trust, Nottingham, England
[2] Inst Psychiat, London, England
[3] Univ Nottingham, Div Psychiat, Nottingham NG7 2RD, England
[4] Univ W Indies, Trinidad, Trinidad Tobago
[5] Univ Bristol, Dept Psychiat Epidemiol, Bristol, Avon, England
[6] Univ Cambridge, Dept Psychiat, Cambridge, England