Footnotes

• Funding The NMR Research Unit is supported by the MS Society Great Britain and Northern Ireland, and Department of Health's NIHR Comprehensive Biomedical Research Centre at UCLH; UB is supported by the MS Society of Switzerland.

• Competing interest AJT has received honoraria for consulting services, speaking, and serving on scientific advisory boards from Novartis, Eisai, Weleda/Society for Clinical Research, Hoffman La Roche, UCB Pharma, Serono Foundation, Sanofi-Aventis and the MS Society of Great Britain and Northern Ireland. He is Editor-in-Chief of Multiple Sclerosis for which he receives an honorarium from Sage Publications. DHM has received honoraria from UCB Pharma, Schering, Biogen Idec, GSK and Wyeth for consulting services, speaking and serving on a scientific advisory boards. He has received reimbursement for work as co-Chief Editor of Journal of Neurology, and research grant support from the MS Society of Great Britain and Northern Ireland, Wellcome Trust, Medical Research Council UK, Biogen Idec, Novartis, GlaxoSmithKline and Schering.

• Ethics approval Ethics approval was provided by the National Hospital for Neurology and Neurosurgery and UCL Institute of Neurology Joint Research Ethics Committee.

• Provenance and peer review Not commissioned; externally peer reviewed.