This study is carried out on the Caribbean island Curacao and in the Netherlands. The population (approx. 150,000 inhabitants) of Curacao is mainly of Negroid descent. Participants were recruited from the Klinika Capriles, (the only psychiatric hospital on the island) the psychiatric ward in the prison (FOBA) and the psychiatric polyclinic on the island (Psychiaters Maatschap Antillen). The study protocol was approved by the Medical Ethical Review Board (Maastricht) and study participants gave written informed consent after explanation about the study.