[1] Norwegian Inst Publ Hlth, Dept Mental Disorders, Box 4404, N-0403 Oslo, Norway
[2] Univ Oslo, Dept Psychol, Oslo, Norway
[3] Univ Oslo, Inst Clin Med, Oslo, Norway
[4] Kings Coll London, MRC, Social Genet & Dev Psychiat Ctr, Inst Psychiat Psychol & Neurosci, London, England
[5] Norwegian Ctr Child Behav Dev, Oslo, Norway
[6] Univ Oslo, Ctr Educ Measurement, Oslo, Norway
[7] Univ Oslo, Dept Special Educ, Oslo, Norway
[8] Norwegian Inst Publ Hlth, Dept Child Dev, Oslo, Norway
[9] Virginia Commonwealth Univ, Dept Human & Mol Genet, Virginia Inst Psychiat & Behav Genet, Richmond, VA USA
[10] Virginia Commonwealth Univ, Dept Psychiat, Richmond, VA USA
[11] Univ Oslo, Sch Pharm, Oslo, Norway