1. South Karelian Central Hospital, Department of Neurology, Lappeenranta, Finland.
2. University of Helsinki, Department of Psychology, Helsinki, Finland.
3. University of Tampere, Department of Psychology, Tampere, Finland.
4. Finnish Institute of Occupational Health, Tampere, Finland.
5. Clinic of Occupational Medicine, Tampere University Hospital, Tampere, Finland.