The prevalence of affective disorders has been increasing in UK adolescents, along with an increase in treatment-seeking for psychological distress . Anxiety and depression are the largest contributors to the mental health global burden of disease, and there are also indications that incidence of psychosis, a serious mental illness, may be increasing in some areas. Adolescent cannabis use is consistently associated with anxiety and psychosis, with less consistent associations for depression. Cannabis use is highly prevalent in adolescent populations and is commonly identified as a target for intervention to reduce likelihood of mental health disorder onset.
However, we do not yet have good evidence that cannabis causes mental health disorders. If the relationship between cannabis use and mental health outcomes is not causal then intervention on adolescent cannabis use will have no impact on mental health. Complexity is introduced by cannabis use and mental health disorders sharing overlapping genetic and environmental risk factors which may cause them to correlate without a causal relationship, or which may change the relationship between cannabis use and mental health outcomes in individuals with these risk factors.
The overall aim of the fellowship is to improve the evidence base on the relationship between adolescent cannabis use and mental health (anxiety, depression and psychosis). We will be comparing results on the relationship between cannabis use and mental health across different cultures to see if this relationship is consistent, and will be using lngitudinal data to undestand how individual and environmental differences impact on the relationship between cannabis use and mental health.