The iPSYCH team acknowledges funding from the Lundbeck Foundation (grant no. R102-A9118 and R155-2014-1724), the Stanley Medical Research Institute, the European Research Council (project 294838), the European Community (EC) Horizon 2020 Programme (grant 667302 (CoCA)), from EC Seventh Framework Programme (grant 602805 (Aggressotype)), the Novo Nordisk Foundation for supporting the Danish National Biobank resource and grants from Aarhus and Copenhagen Universities and University Hospitals, including support to the iSEQ Center, the GenomeDK HPC facility, and the CIRRAU Center.

The Broad Institute and Massachusetts General Hospital investigators would like to acknowledge support from the Stanley Medical Research Institute and NIH grants: 5U01MH094432-04(PI: Daly), 1R01MH094469 (PI: Neale), 1R01MH107649-01 (PI: Neale), 1R01MH109539-01 (PI: Daly).

We thank T. Lehner, A. Addington and G. Senthil for their support in the Psychiatric Genomics Consortium.

S.V.F. is supported by the K.G. Jebsen Centre for Research on Neuropsychiatric Disorders, University of Bergen, Norway, the EC’s Seventh Framework Programme (grant 602805), the EC’s Horizon 2020 (grant 667302) and NIMH grants 5R01MH101519 and U01 MH109536-01.

J.M. was supported by the Wellcome Trust (grant 106047).

B.F.’s research is supported by funding from a personal Vici grant of the Netherlands Organisation for Scientific Research (NWO; grant 016-130-669, to B.F.), the EC’s Seventh Framework Programme (grant 602805 (Aggressotype), 602450 (IMAGEMEND), and 278948 (TACTICS)), and from the EC’s Horizon 2020 Programme (grant643051 (MiND) and 667302 (CoCA)). Additionally, this work was supported by the European College of Neuropsychopharmacology (ECNP Network ‘ADHD across the Lifespan’).

J.H. is supported by grants from Stiftelsen K.G. Jebsen, University of Bergen and The Research Council of Norway.

B.C. received financial support for this research from the Spanish ‘Ministerio de Economía y Competitividad’ (SAF2015-68341-R) and ‘Generalitat de Catalunya/AGAUR’ (2017-SGR-738). B.B., A.R. and collaborators received funding from the EC’s Seventh Framework Programme (grant 602805, Aggressotype), the EC’s H2020 Programme (grants 667302, CoCA, and 402003, MiND), the ECNP network ‘ADHD across the lifespan’ and DFG CRC 1193, subproject Z03.

O.A.A. is supported by the Research Council of Norway (grants: 223273, 248778, 213694, 249711), and KG Jebsen Stiftelsen.

A.T. received ADHD funding from the Wellcome Trust, Medical Research Council (MRC UK), Action Medical Research.

We thank the customers of 23andMe who answered surveys, as well as the employees of 23andMe who together made this research possible. The QIMR studies were supported by funding from the Australian National Health and Medical Research Council (grant numbers: 241944, 339462, 389927, 389875, 389891, 389892, 389938, 443036, 442915, 442981, 496739, 552485, and 552498, and, most recently, 1049894) and the Australian Research Council (grant numbers: A7960034, A79906588, A79801419, DP0212016, and DP0343921). SEM is supported by an NHMRC fellowship (1103623).

Additional acknowledgements can be found in the Supplementary Note.