1. Department of Neurology and Alzheimer Research Center, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
2. Laboratory of Neurochemistry and Behaviour, Institute Born-Bunge, University of Antwerp, Wilrijk, Belgium
3. Institut Jérôme Lejeune, Paris, France
4. Department of Geriatrics, Policlinico Gemelli, Universitá Cattolica del Sacro Cuore, Rome, Italy
5. Down Medical Center, Catalan Down Syndrome Foundation, Barcelona, Spain
6. Ipse de Bruggen, Center for Intellectual Disabilities, Nieuwveen/Zwammerdam, The Netherlands
7. Cosis, Center for Intellectual Disabilities, Groningen, The Netherlands
8. Talant, Center for Intellectual Disabilities, Heerenveen, The Netherlands
9. Pameijer, Center for Intellectual Disabilities, Rotterdam, The Netherlands
10. Aveleijn, Center for Intellectual Disabilities, Borne, The Netherlands
11. Elver, Center for Intellectual Disabilities, Nieuw-Wehl, The Netherlands
12. Department of Neurology and Memory Clinic, Hospital Network Antwerp (ZNA) Middelheim and Hoge Beuken, Antwerp, Belgium
13. Division of Psychiatry, University College London, London, UK
14. Het GielsBos, Center for Intellectual Disabilities, Gierle, Belgium
15. Department of Neurology, University Hospital Antwerp, Antwerp, Belgium
16. Department of Neurology, Hospital de la Santa Creu i Sant Pau, Biomedical Research Institute Sant Pau, Universitat Autònoma de Barcelona, Barcelona, Spain
17. Department of Epidemiology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands
18. Dichterbij, Center for Intellectual Disabilities, Gennep, The Netherlands
19. Department of Primary and Community Care, Radboud University Medical Center, Nijmegen, The Netherlands