1. Institute of Neuroscience and Physiology, Department of Psychiatry and Neurochemistry, Sahlgrenska Academy at the University of Gothenburg, PO Box 430, SE-405 30 Göteborg, Sweden
2. Department of Psychology, University of Gothenburg, PO Box 500, SE-405 30 Göteborg, Sweden
3. Centre for Social Research on Alcohol and Drugs, Stockholm University, SE-106 91 Stockholm, Sweden