Young people's beliefs about the harmfulness of alcohol, cannabis and tobacco for mental disorders: findings from two Australian national youth surveys

Aims Using cross-sectional national survey data, we assessed young peoples' beliefs about the role of alcohol, tobacco and marijuana in the prevention and treatment of mental disorders as well as the predictors of these beliefs. We also compared these findings with those from a similar survey carried out in 2006. Design, setting and participants Between January and May 2011, a national computer-assisted telephone survey was conducted on a representative sample of Australian youths aged 15-25 years. A total of 3021 young people were presented with a case vignette portraying depression, depression with suicidal thoughts, psychosis, social phobia, depression with alcohol misuse or post-traumatic stress disorder in a young person. Measurements Respondents were asked about their beliefs regarding the role of using alcohol, tobacco and marijuana in preventing or dealing with the mental disorders described in the vignettes. Level of psychological distress was assessed by the Kessler 6 scale (K6). Findings More than 75% of respondents agreed that the three substances were harmful for the young people in the vignettes, and that not using marijuana or drinking alcohol in excess is preventive. Males, young adults and more distressed respondents were less likely to endorse these beliefs. No significant changes were observed between surveys. Conclusions Most young people in Australia are aware of the negative impact of substance use on mental disorders, but a few high-risk groups remain: males, young adults and those with more psychological distress. Future public health campaigns need to target these groups and focus on translating young people's substance use beliefs into behavioural change.