Rebecca Fuhrer1, Katherine M Keyes1. 1. Rebecca Fuhrer is with the Department of Epidemiology, Biostatistics, and Occupational Health, McGill University Faculty of Medicine, Montreal, Quebec, Canada. Katherine M. Keyes is with the Department of Epidemiology, Mailman School of Public Health, Columbia University, New York, NY. Rebecca Fuhrer and Katherine M. Keyes are also Guest Editors for this supplement issue.