Beliefs of young people and their parents about the harmfulness of alcohol, cannabis and tobacco for mental disorders.

OBJECTIVE: To ascertain the beliefs of young people and their parents about the role of alcohol, tobacco and marijuana in the prevention and treatment of mental disorders.

DESIGN, SETTING AND PARTICIPANTS: Between May and August 2006, a national computer-assisted telephone survey was conducted on a representative sample of Australian youths aged 12-25 years. 3746 young people and 2005 of their parents were presented with a case vignette portraying psychosis, depression, depression with alcohol misuse, or social phobia in a young person.

MAIN OUTCOME MEASURES: Participants' beliefs regarding the role of substance use in preventing or dealing with mental disorders in young people.

RESULTS: Over 85% of participants agreed that alcohol, tobacco and marijuana were harmful for the young people in the vignettes, and over 80% of youths agreed that not using marijuana or drinking alcohol in excess would reduce the risk of developing a similar problem.

CONCLUSION: Young people and their parents are fully aware of the negative impact of substance use on mental disorders. Translating this knowledge into behavioural change will be a major challenge for future public health campaigns.