One in ten young teens with mental health issues are consuming alcohol, cigarettes and cannabis weekly.
Researchers collected information from more than 2000 people aged 12-30 who attended headspace youth mental health clinics, and found patterns of substance abuse become more commons as young teens grow, contributing to poor health.
According to the study, the average age at which these patterns start is 15, with users of the substances more likely to be male, older and to have psychotic or bipolar disorders.
Read more at University of Sydney