[1] Univ Kuopio, Dept Neurol, Kuopio, Finland
[2] Univ Kuopio, Dept Med, Kuopio, Finland
[3] Univ Coimbra, Dept Neurol, P-3000 Coimbra, Portugal
[4] Univ Essen Gesamthsch, Dept Neurol, Essen, Germany
[5] Univ Dundee, Ninewells Hosp & Med Sch, Dept Med, Dundee DD1 9SY, Scotland
[6] Med Res OCMW, Antwerp, Belgium
[7] Free Univ Brussels, Dept Stat, Brussels, Belgium