Cannabis use is increasing among adolescents internationally with an estimated 10% of adolescents in the US using cannabis daily. Ireland currently has the 9th highest rate of adolescent “high risk” cannabis use in Europe. The potency of cannabis products has also increased and high potency cannabis is more likely to lead to adverse outcomes for young people in terms of addiction and mental health problems such as psychosis, suicidal behaviours and depression. A recent meta-analysis from our group has shown decreases in IQ among adolescents who use cannabis. It is important to investigate the effects of early cannabis use on the adolescent developing brain. We must also continue efforts to prevent young people from starting cannabis use and to identify factors that increase the likelihood of a young person starting to use cannabis in adolescence.
This programme of research has two main aims. Firstly, we aim to identify risk and protective factors for both initiation and persistence of cannabis use among adolescents. We will investigate these interacting and multivariate factors using complex statistical modelling in two large population-based samples of young people in Ireland: the Growing Up in Ireland study – our national longitudinal cohort of 8000 young people between ages 9 and 20; and Planet Youth, a large school-based survey of 12000 15 and 16 year-olds in selected regions across Ireland. Secondly, we will use two datasets (one Irish and one from US) that have neuroimaging and neurocognitive data before and after cannabis use in adolescence.
A key feature of our proposal is the establishment of a Public Patient Involvement Advisory group from the outset. We have co-funding from the Department of Health for this initiative which will greatly enhance the impact of our study and allow our findings to be integrated into policy and preventive measures.