The CSC intervention: A comprehensive universal internet-based intervention to prevent anxiety, depression, substance use, and related harms in Australian adolescents aged 13 to 16 years.

Participating secondary schools will be randomly allocated to one of four groups. Group 1: The Control condition: One group will serve as the control group and receive their usual school drug and mental health education. The following groups will receive one of the following three study interventions: Group 2: The Climate Schools-Substance Use (CS-SU) intervention aims to reduce the use of Australia’s most commonly used licit and illicit drugs: alcohol and cannabis, and prevent related harms. The program consists of twelve 40-minute lessons delivered as part of the Year 8 (Year 9 in QLD) Health and Physical Education syllabus. The first six lessons will be delivered in Term 1, 2014 during consecutive Health and Physical education classes (approximately 1 lesson per week). The remaining six lessons will be delivered in Term 3, 2014 in consecutive Health and Physical education classes (approximately 1 lesson per week). The first part of each lesson is completed individually over the internet. During this part of the lesson students are engaged through cartoon story lines that impart information about the short and long term effects of alcohol and cannabis, normative alcohol and cannabis use, refusal skills, and first aid. The second part of each lesson is a group or class activity delivered by the teacher, and reinforces the information in the cartoons, while allowing interactive communication between students. Teachers are provided with a manual containing the activities, implementation guidelines, links to the education syllabus and summaries for each lesson. The first six lessons focus specifically on alcohol and are delivered approximately six months prior to the remaining six lessons which focus on cannabis. Group 3: The Climate Schools-Mental Health (CS-MH) intervention aims to reduce anxiety and depression symptoms, and to prevent the development of associated disorders later in life. The program consists of six 40-minute lessons delivered as part of the Year 9 (Year 10 in QLD) Health and Physical Education syllabus. The six lessons will be delivered in Term 1,2015 in consecutive Health and Physical education classes (approximately 1 lesson per week). The lessons are structured in the same way as the Climate Schools-Substance Use intervention. The content of the lessons focuses on identifying and effectively dealing with anxiety and depression symptoms. The six lessons are designed to be run consecutively within one school Term. Group 4: The Climate Schools Combined (CSC) Intervention will deliver both the Climate Schools-Substance Use and the Climate Schools-Mental Health interventions consecutively, as described above. The CSC intervention simultaneously targets mental health and substance use, as it is known that the two commonly co-occur and share common risk factors. For those groups receiving an intervention, teachers will be asked to complete a log book at the end of the intervention to document adherence to the intervention and record which activities they implemented in the classroom. As students are required to log in to complete the study intervention online records will indicate student completion rates. Regardless of group, teachers will be asked at the end of each year during the study period to record any other drug, alcohol or mental health education that was delivered to students participating in the trial, that was in addition to the Climate Schools courses. CSC LONG TERM FOLLOW UP 2018-2022 The CSC long-term follow up is an opportunistic extension of the landmark CSC study, whereby follow up of this cohort will extend beyond the completion of secondary school and into the critical transition period of early adulthood. The investigators will extend longitudinal follow-up for a further 5 years, inviting the participants to take part in two additional online surveys assessing demographic information, drinking and drug use habits, mental health systems, health service use and behavioural and personality inventories. Consent will also be sought to link to participants MBS and PBS data. A cost-effectiveness analysis will also examine the cost-effectiveness of the prevention program. This extended follow-up component was added after initial recruitment for Phase 1 of the CSC trial, run between 2014 – 2017.