1. Department of Psychiatry and Internal Medicine, University of Groningen, Hanzeplein 1, Gebouw 32, PO Box 30.001, 9700 RB, Groningen, The Netherlands
2. Department of Psychiatry, VU Hospital Amsterdam and Academic Hospital Groningen, The Netherlands
3. Department of Internal Medicine, University Hospital Groningen, The Netherlands
4. Department of Psychosomatics and Psychotherapy, General Hospital Nuremberg, Nuremberg, Germany
5. Department of Psychiatry, University Hospital Lausanne, Lausanne, Switzerland