We thank all participants and their families for participating in this study. We gratefully acknowledge the contributions of all members of the EU-AIMS LEAP group: Jumana Ahmad, Sara Ambrosino, Bonnie Auyeung, Tobias Banaschewski, Simon Baron-Cohen, Sarah Baumeister, Christian F Beckmann, Sven Bölte, Thomas Bourgeron, Carsten Bours, Michael Brammer, Daniel Brandeis, Claudia Brogna, Yvette de Bruijn, Jan K Buitelaar, Bhismadev Chakrabarti, Tony Charman, Ineke Cornelissen, Daisy Crawley, Flavio Dell’Acqua, Guillaume Dumas, Sarah Durston, Christine Ecker, Jessica Faulkner, Vincent Frouin, Pilar Garcés, David Goyard, Lindsay Ham, Hannah Hayward, Joerg Hipp, Rosemary J Holt, Mark H Johnson, Emily J H Jones23, Prantik Kundu, Meng-Chuan Lai, Xavier Liogier D’ardhuy, Michael V. Lombardo, Eva Loth, David J Lythgoe, René Mandl, Andre Marquand, Luke Mason, Maarten Mennes, Andreas Meyer-Lindenberg, Carolin Moessnang, Nico Mueller, Declan G M Murphy, Bethany Oakley, Laurence O’Dwyer, Marianne Oldehinkel, Bob Oranje, Gahan Pandina, Antonio M Persico, Annika Rausch, Barbara Ruggeri, Amber Ruigrok, Jessica Sabet, Roberto Sacco, Antonia San José Cáceres, Emily Simonoff, Will Spooren, Julian Tillmann, Roberto Toro, Heike Tost, Jack Waldman, Steve C R Williams, Caroline Wooldridge, Iva Ilioska, Ting Mei and Marcel P Zwiers.

The EU AIMS LEAP group affiliations: Jumana Ahmad11, Sara Ambrosino4, Bonnie Auyeung7,14, Tobias Banaschewski6, Simon Baron-Cohen7, Sarah Baumeister6, Christian F Beckmann1, Sven Bölte15,16, Thomas Bourgeron17, Carsten Bours1, Michael Brammer12, Daniel Brandeis6, Claudia Brogna18, Yvette de Bruijn1, Jan K Buitelaar1, Bhismadev Chakrabarti7,19, Tony Charman3, Ineke Cornelissen1, Daisy Crawley8, Flavio Dell’Acqua8, Guillaume Dumas17, Sarah Durston4, Christine Ecker3,8,9, Jessica Faulkner8, Vincent Frouin13, Pilar Garcés20, David Goyard13, Lindsay Ham21, Hannah Hayward8, Joerg Hipp20, Rosemary J Holt7, Mark H Johnson23, Emily J H Jones23, Prantik Kundu24, Meng-Chuan Lai7,25, Xavier Liogier D’ardhuy20, Michael V. Lombardo7,26, Eva Loth8,11, David J Lythgoe12, René Mandl4, Andre Marquand1, Luke Mason23, Maarten Mennes1, Andreas Meyer-Lindenberg5, Carolin Moessnang5, Nico Mueller6, Declan G.M. Murphy8,11, Bethany Oakley8, Laurence O’Dwyer1, Marianne Oldehinkel1, Bob Oranje4, Gahan Pandina27, Antonio M. Persico18,28, Jack Price3, Annika Rausch1, Barbara Ruggeri29, Amber N V Ruigrok7, Jessica Sabet8, Roberto Sacco18, Antonia San Jóse Cáceres8, Emily Simonoff31, Will Spooren30, Julian Tillmann3, Roberto Toro17, Heike Tost5, Jack Waldman7, Steve C R Williams12, Caroline Wooldridge12, Iva Ilioska1, Ting Mei1 and Marcel P Zwiers1

1Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Kapittelweg 29, 6525 EN, Nijmegen, The Netherlands; 3Department of Psychology, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, De Crespigny Park, Denmark Hill, London, SE5 8AF, UK; 4Department of Psychiatry, Brain Center Rudolf Magnus, University Medical Center Utrecht, Universiteitsweg 100, 3584 CG, Utrecht, The Netherlands; 5Department of Psychiatry and Psychotherapy, Central Institute of Mental Health, Medical Faculty Mannheim, University of Heidelberg, 68159, Mannheim, Germany; 6Child and Adolescent Psychiatry, Central Institute of Mental Health, University of Heidelberg, Medical Faculty Mannheim, J5, 68159, Mannheim, Germany; 7Autism Research Centre, Department of Psychiatry, University of Cambridge, Douglas House, 18b Trumpington Road, Cambridge, CB2 8AH, UK; 8Department of Forensic and Neurodevelopmental Sciences, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, De Crespigny Park, Denmark Hill, London, SE5 8AF, UK; 9Department of Child and Adolescent Psychiatry, Psychosomatics and Psychotherapy, University Hospital Frankfurt am Main, Goethe University, Deutschordenstrasse 50, 60528, Frankfurt, Germany; 11Sackler Institute for Translational Neurodevelopment, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, De Crespigny Park, Denmark Hill, London, SE5 8AF, UK; 12Department of Neuroimaging, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, De Crespigny Park, Denmark Hill, London, SE5 8AF, UK; 13Neurospin Centre CEA, Saclay, 91191, Gif sur Yvette, France; 14The School of Philosophy, Psychology, and Language Sciences, University of Edinburgh, Dugald Stewart Building, 3 Charles Street, Edinburgh, EH8 9AD, UK; 15Center for Neurodevelopmental Disorders at Karolinska Institutet (KIND), Stockholm, Sweden; 16Child and Adolescent Psychiatry, Center of Psychiatry Research, Stockholm County Council, Stockholm, Sweden; 17Institut Pasteur, Human Genetics and Cognitive Functions Unit, 25 Rue du Docteur Roux, Paris, Cedex 15, France; 18University Campus Bio-Medico, Via Álvaro del Portillo, 21, Rome, Italy; 19School of Psychology and Clinical Language Sciences, University of Reading, Whiteknights, Reading, RG6 6AL, UK; 20Roche Pharma Research and Early Development, Neuroscience, Ophthalmology and Rare Diseases, Roche Innovation Center Basel, Grenzacherstrasse 124, B.001 N.667, CH-4070, Basel, Switzerland; 21Regulatory Affairs, Pharmaceutical Development, F. Hoffmann-La Roche Pharmaceuticals, Grenzacherstrasse 124, CH-4070, Basel, Switzerland; 22Department of Neuroscience, Uppsala University, Uppsala, Sweden; 23Centre for Brain and Cognitive Development, Birkbeck, University of London, 32 Torrington Square, London, WC1E 7JL, UK; 24Department of Radiology, Icahn School of Medicine at Mount Sinai, NY, USA; 25Child and Youth Mental Health Collaborative, Centre for Addiction and Mental Health and The Hospital for Sick Children, Department of Psychiatry, University of Toronto, 80 Workman Way, Toronto, ON, M6J 1H4, Canada; 26Center for Applied Neuroscience, Department of Psychology, University of Cyprus, PO Box 20537, 1678, Nicosia, Cyprus; 27Janssen Research & Development, 1125 Trenton Harbourton Road, Titusville, NJ, 08560, USA; 28Child and Adolescent Neuropsychiatry Unit, “Gaetano Martino” University Hospital, University of Messina, via Consolare Valeria 1, I-98125, Messina, Italy; 29Social, Genetic and Developmental Psychiatry Centre, Institute of Psychiatry, Psychology and Neuroscience, King’s College London, Denmark Hill, London, UK; 30Roche Pharmaceutical Research and Early Development, NORD Discovery and Translational Area, Roche Innovation Center Basel, Grenzacherstrasse 124, CH-4070, Basel, Switzerland; 31Department of Child and Adolescent Psychiatry, Institute of Psychology, Psychiatry and Neuroscience, King’s College London, De Crespigny Park, Denmark Hill, London, SE5 8LF, UK