Declaration of Conflicting Interests: Dr. Courtney reports grants and personal fees from Cundill Centre for Child and Youth Depression, grants from Centre for Addiction and Mental Health (CAMH) Discovery Fund, outside the submitted work. Dr. Watson reports grants and personal fees from Cundill Centre for Child and Youth Depression, and grants from CAMH Alternate Funding Plan Innovation Fund, outside the submitted work. Dr. Battaglia reports grants from the Canadian Institute for Health Research, the Cundill Centre for Child and Youth Depression, and the CAMH Discovery Fund, outside the submitted work. Dr. Mulsant reports grants from Brain Canada, grants from Canadian Institutes of Health Research, grants from the CAMH Foundation, grants from Patient-Centred Outcomes Research Institute (PCORI), grants from U.S. National Institutes of Health, nonfinancial support from Eli Lilly, nonfinancial support from Pfizer, non-financial support from Capital Solutions Design LLC, nonfinancial support from HAPPYneuron, other from General Electric, outside the submitted work. Dr. Szatmari reports personal fees from Guildford Press, personal fees from Simon and Schuster.