1. Department of Neurology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
2. Department of Neuropsychology, University of Groningen, University Medical Center Groningen, Groningen, The Netherlands.
3. Department of Neurology, Medical Spectrum Twente, Enschede, The Netherlands.
4. Department of Neurology, St. Elisabeth Hospital, Tilburg, The Netherlands.