1 Department of Psychiatry, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA, Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA, Department of Psychiatry, Dalhousie Faculty of Medicine, Halifax, Nova Scotia, Canada and murphy.jane@mgh.harvard.edu.
2 Department of Epidemiology, Harvard School of Public Health, Boston, MA, USA.
3 Department of Epidemiology and Community Medicine, University of Ottawa, Ottawa, Ontario, Canada.