1. Department of Adult Mental Health, Division of Mental Health, Norwegian Institute of Public Health, Oslo, Norway
2. Departments of Psychiatry and Nutrition, University of North Carolina at Chapel Hill, North Carolina, USA
3. Department of Psychiatry, University of North Carolina at Chapel Hill, North Carolina, USA
4. Departments of Psychiatry and Genetics, University of North Carolina at Chapel Hill, North Carolina, USA
5. Department of Adult Mental Health, Division of Mental Health, Norwegian Institute of Public Health, PO Box 4404 Nydalen, NO-0403, Oslo, Norway
6. Department of Psychiatry, University of Oslo, Oslo, Norway
7. Department of Epidemiology, Columbia University, New York, USA