[1] McMaster Univ, Peter Boris Ctr Addict Res, Hamilton, ON, Canada
[2] St Josephs Hlth Care, Hamilton, ON, Canada
[3] Homewood Res Inst, Guelph, ON, Canada
[4] Massachusetts Gen Hosp, Recovery Res Inst, Boston, MA 02114 USA
[5] Harvard Med Sch, Dept Psychiat, Boston, MA 02115 USA