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, Antwerp, Belgium
3. Dichterbij, Center for the Intellectually Disabled, Gennep, The Netherlands
4. Department of Epidemiology, Erasmus University Medical Center, Rotterdam, The Netherlands
5. Department of Primary and Community Care, Radboud University Medical Center, Nijmegen, The Netherlands