[1] Univ Groningen, Univ Med Ctr Groningen, Dept Neurol, Groningen, Netherlands
[2] Univ Groningen, Univ Med Ctr Groningen, Alzheimer Res Ctr, Groningen, Netherlands
[3] Univ Antwerp, Inst Born Bunge, Lab Neurochem & Behav, Antwerp, Belgium
[4] Inst Jerome Lejeune, Paris, France
[5] Univ Cattolica Sacro Cuore, Policlin Gemelli, Dept Geriatr, Rome, Italy
[6] Catalan Down Syndrome Fdn, Down Med Ctr, Barcelona, Spain
[7] Ipse Bruggen, Ctr Intellectual Disabil, Nieuwveen Zwammerdam, Netherlands
[8] Cosis, Ctr Intellectual Disabil, Groningen, Netherlands
[9] Talant, Ctr Intellectual Disabil, Heerenveen, Netherlands
[10] Pameijer, Ctr Intellectual Disabil, Rotterdam, Netherlands
[11] Aveleijn, Ctr Intellectual Disabil, Borne, Netherlands
[12] Elver, Ctr Intellectual Disabil, Nieuw Wehl, Netherlands
[13] Hosp Network Antwerp ZNA Middelheim & Hoge Beuken, Dept Neurol, Antwerp, Belgium
[14] Hosp Network Antwerp ZNA Middelheim & Hoge Beuken, Memory Clin, Antwerp, Belgium
[15] UCL, Div Psychiat, London, England
[16] NHet GielsBos, Ctr Intellectual Disabil, Gierle, Belgium
[17] Univ Hosp Antwerp, Dept Neurol, Antwerp, Belgium
[18] Univ Autonoma Barcelona, Biomed Res Inst Sant Pau, Hosp Santa Creu & Sant Pau, Dept Neurol, Barcelona, Spain
[19] Univ Groningen, Univ Med Ctr Groningen, Dept Epidemiol, Groningen, Netherlands
[20] Ctr Intellectual Disabil, Dichterbij, Gennep, Netherlands
[21] Radboud Univ Nijmegen, Med Ctr, Dept Primary & Community Care, Nijmegen, Netherlands