The study protocol adhered strictly to the guidelines contained in the Declaration of Helsinki (2008). All procedures were approved by the Western Cape Education Department and the Research Ethics Committee of the Stellenbosch University Faculty of Health Sciences. Written assent and consent were obtained from participants and their parents, respectively. Participant screening included a physical examination (including urine analysis and breathalyzer testing) and assessment of psychiatric and medical histories. After screening was complete, participants completed a demographic questionnaire.
