1. Alcohol, Tobacco and Other Drug Research Unit; South African Medical Research Council; Cape Town South Africa
2. Department of Psychiatry and Mental Health; University of Cape Town; Cape Town South Africa
3. Department of Paediatrics and Child Health; Red Cross War Memorial Children's Hospital; University of Cape Town; Cape Town South Africa
4. Division of Epidemiology and Biostatistics; School of Public Health and Family Medicine; University of Cape Town; Cape Town South Africa
5. South African Medical Research Council Unit on Child and Adolescent Health; Cape Town South Africa
6. South African Medical Research Council Unit on Anxiety and Stress Disorders; Cape Town South Africa