1 Norwegian Centre for Addiction Research, University of Oslo, Norway.
2 National Centre for Suicide Research and Prevention, University of Oslo, Norway Department of Psychiatry, Diakonhjemmet Hospital, Oslo, Norway.
3 Department of Psychiatry, St. Olav University Hospital, Trondheim, Norway Department of Neuroscience, Norwegian University of Science and Technology, Trondheim, Norway.
4 Norwegian Centre for Addiction Research, University of Oslo, Norway Department of Biostatistics, University of Oslo, Norway.