Congratulations to Carolyn Coffey on the completion of her PhD.
One of the major health risks for young people to emerge in recent decades relates to illicit drug use with cannabis being the most commonly used in Australia.  Yet there has been remarkably little work undertaken into quantifying the health risk associated with cannabis. This thesis is a narrative based on twelve papers published in international peer reviewed journals arising from the Victorian Adolescent Health Cohort Study, which have contributed to our understanding of the natural history of adolescent cannabis use and the adverse consequences that may arise from its use in adolescence and young adulthood. Dr Coffey was intimately involved with this ongoing population-based cohort study which commenced in 1992 with 2000 fourteen-year-olds who were interviewed periodically until they were aged 29 years in 2010. This unique data set allowed her to track the transitions in behaviour through adolescence into adulthood and the longer term impact of cannabis use measured. The overall conclusion must be that cannabis use in adolescence is not harmless and, for some, has quite grave consequences in adulthood. The findings have already done much to shift community attitudes and policy responses.