1 Department of Psychiatry and Behavioral Sciences, University of Washington School of Medicine, Adolescent Substance Abuse Program, Seattle Children's Hospital, M/S OA.5.154, PO Box 5371, Seattle, WA 98145-5005, USA. Electronic address: rhsiao@uw.edu.
2 Division of Substance Dependence, Department of Psychiatry, University of Colorado School of Medicine, Mail Stop F478, 12469 East 17th Place, Building 400, Aurora, CO 80045, USA. Electronic address: paula.riggs@ucdenver.edu.