[1] UCL, Res Dept Clin Educ & Hlth Psychol, London WC1E 7HB, England
[2] Univ Leeds, Leeds Inst Hlth Sci, Leeds, W Yorkshire, England
[3] Kings Coll London, Inst Psychiat Psychol & Neurosci, London, England
[4] Anna Freud Natl Ctr Children & Families, London, England
[5] Univ Leeds, Leeds, W Yorkshire, England
[6] South West Yorkshire Partnership NHS Fdn Trust, Leeds, W Yorkshire, England
[7] Univ Cambridge, MRC Biostat Unit, Cambridge, England
[8] Univ Cambridge, Dept Psychiat, Cambridge, England