The aims of the current study were to 1) establish the efficacy of two Internet-based prevention programmes to reduce anxiety and depressive symptoms in adolescents; and 2) investigate the distribution of psychological symptoms in a large sample of Australian adolescents prior to the implementation of the intervention. A cluster randomised controlled trial was conducted with 976 Year 9–10 students from twelve Australian secondary schools in 2009. Four schools were randomly allocated to the Anxiety Internet-based prevention programme (n=372), five schools to the Depression Internet-based prevention programme (n=380) and three to their usual health classes (n=224). The Thiswayup Schools for Anxiety and Depression prevention courses were presented over the Internet and consist of 6–7 evidence-based, curriculum consistent lessons to improve the ability to manage anxiety and depressive symptoms. Participants were assessed at baseline and post-intervention. Data analysis was constrained by both study attrition and data corruption. Thus post-intervention data were only available for 265/976 students. Compared to the control group, students in the depression intervention group showed a significant improvement in anxiety and depressive symptoms at the end of the course, whilst students in the anxiety intervention demonstrated a reduction in symptoms of anxiety. No significant differences were found in psychological distress. The Thiswayup Schools Depression and Anxiety interventions appear to reduce anxiety and depressive symptoms in adolescents using a curriculum based, blended online and offline cognitive behavioural therapy programme that was implemented by classroom teachers. Given the study limitations, particularly the loss of post-intervention data, these findings can only be considered preliminary and need to be replicated in future research. 
Preventing anxiety and depression in adolescents: A randomised controlled trial of two school based Internet-delivered cognitive behavioural therapy programmes