1. Department of Neurology, Kangwon National University, Chuncheon, Korea.
2. Department of Neurology, Korea University Medical Center, Korea University College of Medicine, Seoul, Korea.
3. Seoul Brain Neurology Clinic, Seoul, Korea.
4. Department of Neurology, Keimyung University Dongsan Medical Center, Daegu, Korea.
5. Department of Neurology, Konkuk University Medical Center, Seoul, Korea.
6. Department of Social and Preventive Medicine, Inha University School of Medicine, Incheon, Korea.
7. Department of Research and Statistics, Health Insurance Review & Assessment Service, Seoul, Korea.