[1] Cardiff Univ, Sch Healthcare Sci, Heath Pk, Cardiff CF14 4XN, S Glam, Wales
[2] Columbia Univ, Teachers Coll, Dept Biobehav Sci, 525 West 120th St,Box 199, New York, NY 10027 USA
[3] Cardiff Univ, Ctr Trials Res, South East Wales Trials Unit, Cardiff CF10 3AX, S Glam, Wales
[4] Oxford Brookes Univ, Oxford Inst Nursing & Allied Hlth Res, Oxford OX3 0BP, England
[5] Leiden Univ, Med Ctr, Dept Neurol, Leiden, Netherlands
[6] George Huntington Inst, Munster, Germany
[7] Univ Munster, Dept Radiol, Munster, Germany
[8] Univ Tubingen, Dept Neurodegenerat Dis, Tubingen, Germany
[9] Univ Tubingen, Hertie Inst Clin Brain Res, Tubingen, Germany
[10] Vikersund Rehabil Ctr, Vikersund, Norway
[11] Univ Oslo, Fac Med, N-0316 Oslo, Norway
[12] Univ Birmingham, Inst Clin Sci, Birmingham B15 2TT, W Midlands, England
[13] Cardiff Univ, Sch Med, MRC Ctr Neuropsychiat Genet & Genom, Cardiff Brain Repair Grp,Neurosci & Mental Hlth I, Cardiff CF10 3BB, S Glam, Wales
[14] Cardiff Univ, Sch Biosci, MRC Ctr Neuropsychiat Genet & Genom, Cardiff Brain Repair Grp,Neurosci & Mental Hlth I, Cardiff CF10 3BB, S Glam, Wales