1. Division of Mental Health and Addiction, Oslo University Hospital, Oslo, Norway.
2. Department of Chronic Diseases and Ageing, Norwegian Institute of Public Health, Oslo, Norway.
3. Norwegian National Advisory Unit on Concurrent Substance Abuse and Mental Health Disorders, Innlandet Hospital Trust, Hamar, Norway.
4. Faculty of Health and Social Science, Inland University College of Applied Science, Elverum, Norway.
5. Department of Alcohol, Tobacco and Drugs, Norwegian Institute of Public Health, Oslo, Norway.
6. Institute of Clinical Medicine, UiT—The Arctic University of Norway, Tromsø, Norway.