1. Department of Neurology, Leiden University Medical Center, Albinusdreef 2, 2333 ZA Leiden, The Netherlands
2. Department of Neurology, Haaglanden Medical Center, Burg. Banninglaan, 2262 BA Leidschendam, The Netherlands
3. Department of Public Health & Primary Care, Leiden University Medical Center, Albinusdreef 2, 2333 ZA, Leiden, The Netherlands