1. Outpatient Clinic for Behavioral Addictions, Department of Psychosomatic Medicine and Psychotherapy, University Medical Center of the Johannes Gutenberg-University Mainz, Untere Zahlbacher Str. 8, 55131, Mainz, Germany
2. Interdisciplinary Center for Clinical Trials (IZKS) Mainz, University Medical Center of the Johannes Gutenberg-University Mainz, Langenbeckstraße 1 D-55131, Mainz, Germany
3. Department of Psychiatry and Psychotherapy, Section for Addiction Research and Medicine, University Hospital of Tuebingen, Geissweg 3, 72076, Tübingen, Germany
4. Medical Faculty Mannheim, Department of Addictive Behaviour and Addiction Medicine, Central Institute of Mental Health, Heidelberg University, J5, 68159, Mannheim, Germany
5. Department of Psychiatry, Anton Proksch Institute, Gräfin Zichy Straße 4-6, 1230, Vienna, Austria