1. Department of Neurology University of Pennsylvania School of Medicine Philadelphia Pennsylvania USA
2. Department of Neurology Thomas Jefferson University Hospital Philadelphia Pennsylvania USA
3. Department of Biostatistics, Epidemiology, & Informatics University of Pennsylvania School of Medicine Philadelphia Pennsylvania USA
4. Department of Psychology Drexel University Philadelphia Pennsylvania USA
5. Department of Neurology University of Pittsburgh Pittsburgh Pennsylvania USA
6. Parkinson's Disease Research Education, and Clinical Center, Crescenz Veterans Affairs Medical Center Philadelphia Pennsylvania USA
7. Department of Pathology and Laboratory Medicine University of Pennsylvania School of Medicine Philadelphia Pennsylvania USA
8. Department of Psychiatry University of Pennsylvania School of Medicine Philadelphia Pennsylvania USA