1. School of Social & Community Medicine University of Bristol Bristol UK
2. Section of Child & Adolescent Psychiatry Department of Psychiatry University of Oxford Oxford UK
3. Child and Family Research Eunice Kennedy Shriver National Institute of Child Health and Human Development Bethesda MD USA
4. Department of Experimental Psychology University of Oxford Oxford UK
5. Institute of Psychological Medicine and Clinical Neurosciences Cardiff University Cardiff UK
6. School of Public Health University of Witwatersrand Johannesburg South Africa