University Hospital Tuebingen, Federal Ministry of Health, Germany, Institute of Clinical Epidemiology and applied Biometry, University Tuebingen, Germany, Center of Clinical Trials, University Tuebingen, Germany, University of Ulm, Department of Psychiatry and Psychotherapy, University Regensburg, Germany, Department of Psychiatry and Psychotherapy, University Wuerzburg, Germany, Department of Psychiatry and Psychotherapy, University Munich (LMU), Germany, Department of Psychiatry and Psychotherapy, University Leipzig, Germany, Department of Psychiatry, Psychotherapy and Psychosomatics, Medical Faculty, University of Augsburg, Bezirkskrankenhaus Augsburg, Germany