[1] Univ Helsinki, Inst Behav Sci, POB 9, FIN-00014 Helsinki, Finland
[2] Natl Inst Hlth & Welf, Helsinki, Finland
[3] Folkhalsan Res Ctr, Helsinki, Finland
[4] Univ Helsinki, Childrens Hosp, Helsinki, Finland
[5] Helsinki Univ Hosp, Helsinki, Finland
[6] Univ Warwick, Dept Psychol, Coventry, W Midlands, England
[7] Natl Inst Hlth & Welf, Helsinki, Finland
[8] Natl Inst Hlth & Welf, Oulu, Finland
[9] Oulu Univ Hosp, PEDEGO Res Unit, MRC Oulu, Oulu, Finland
[10] Univ Oulu, Oulu, Finland
[11] Folkhalsan Res Ctr, Natl Inst Hlth & Welf, Helsinki, Finland
[12] Univ Helsinki, Dept Gen Practice & Primary Hlth Care, Helsinki, Finland