After the recent publication of our article (Williams JR, Marsh L. Movement Disorders 2009 24(3):433–7), we found three errors in the acknowledgement of our NIH grant support. We apologize to the readers for these errors, which are corrected in the present erratum.

Support for this study was provided by the NIH [R01-MH-069666, T32-AG-027668, Morris K. Udall Parkinson's Disease Research Center of Excellence at Johns Hopkins (P50-NS-58377), and the General Clinical Research Center at Johns Hopkins University School of Medicine (National Center for Research Resources UL1-RR-025005)]; the Donna Jean Baumann Fund; the Weldon Hall Trust; and the Parkinson's Disease Foundation Student Fellowship Program (J.R. Williams).