Accepted for Publication: August 18, 2011.
Published Online: February 6, 2012. doi:10.1001/archneurol.2011.1658
Author Contributions:Study concept and design: van der Lei and van der Knaap. Acquisition of data: van der Lei, Steenweg, Bugiani, Pouwels, Vent, and Barkhof. Analysis and interpretation of data: van der Lei, Steenweg, Pouwels, van Wieringen, and van der Knaap. Drafting of the manuscript: van der Lei and van der Knaap. Critical revision of the manuscript for important intellectual content: Steenweg, Bugiani, Pouwels, Vent, Barkhof, and van Wieringen. Statistical analysis: van der Lei and van Wieringen. Obtained funding: van der Knaap. Administrative, technical, and material support: Vent and Barkhof. Study supervision: van der Knaap.
Financial Disclosure: None reported.
Funding/Support: Financial support was provided by the Optimix Foundation for Scientific Research, ZonMw TOP grant 9120.6002 and ZonMw AGIKO grant 920-03-308 from the Dutch Organisation for Scientific Research, and grant 2008029 WO from the Dr WM Phelps Foundation.
Role of the Sponsor: The funding agencies had no direct involvement with the content of the studies in any way.
Additional Contributions: We thank all the patients, families, and colleagues who contributed to our studies.