The authors are grateful to the participants and thank the staff at the Krókháls recruitment center. We thank P. Arp, M. Jhamai, M. Moorhouse, M. Verkerk and S. Bervoets for their assistance in creating the GWAS database. The authors are very grateful to the participants and staff from the Rotterdam Study, participating general practitioners and the pharmacists. The Netherlands Twin Registry thanks all participants. The research leading to these results has received support from the Innovative Medicines Initiative Joint Undertaking under grant agreement 115008, resources of which are composed of European Federation of Pharmaceutical Industries and Associations (EFPIA) in-kind contributions and financial contributions from the European Union's Seventh Framework Programme (FP7/2007-2013) and the European Union–funded FP7-People-2011-IAPP grant PsychDPC (GA 286213). This study presents independent research funded in part by the National Institute for Health Research (NIHR) Biomedical Research Centre at South London and Maudsley, NHS Foundation Trust and King's College London. The views expressed are those of the authors and not necessarily those of the UK National Health Service, the NIHR or the Department of Health. The Rotterdam Study was funded by the Netherlands Organisation for Scientific Research NWO Investments (175.010.2005.011, 911-03-012), the Research Institute for Diseases in the Elderly (014-93-015; RIDE2) and the Netherlands Genomics Initiative (NGI)/Netherlands Consortium for Healthy Aging (NCHA) project 050-060-810. The Rotterdam Study is funded by the Erasmus Medical Center; Erasmus University, Rotterdam; the Netherlands Organization for the Health Research and Development (ZonMw); the Research Institute for Diseases in the Elderly (RIDE); the Ministry of Education, Culture, and Science; the Ministry for Health, Welfare, and Sports; the European Commission (DG XII); and the Municipality of Rotterdam. Funding for the Netherlands Twin Registry was obtained from the Netherlands Organization for Scientific Research (NWO) and MagW/ZonMW, BBMRI-NL (184.021.007), the VU University Institute for Health and Care Research (EMGO+) and Neuroscience Campus Amsterdam, the European Science Council (ERC) Genetics of Mental Illness (230374), Avera Institute for Human Genetics and US National Institute of Mental Health (1RC2MH089951-01 and 1RC2 MH089995). The Swedish Twin Registry was financially supported by the Ragnar Söderberg Foundation (E9/11), the Swedish Research Council (421-2013-1061), the Jan Wallander and Tom Hedelius Foundation (P2012-0002:1), the Sven and Dagmar Salén Foundation, the Bank of Sweden Tercentenary Foundation (M11-0451:1) and the Karolinska Institutet. Some of the statistical analyses were carried out on the Genetic Cluster Computer (http://www.geneticcluster.org/), which is financially supported by the Netherlands Scientific Organization (NWO 480-05-003 PI: Posthuma) along with a supplement from the Dutch Brain Foundation and the VU University Amsterdam.