Patterns of cigarette and cannabis use across adolescence and later cognition and emotional processing: improving causal inference

The aim of this study is to investigate the causal association between cigarette and cannabis use (assessed across adolescence) and cognition/emotional processing (assessed in young adulthood) using a combination of observational and genetic data sources. Although several studies have examined the association between these substances and cognition/emotional processing, these are usually not able to distinguish correlation from causation. Utilising a triangulation approach helps to improve causal inference by i) using observational data to identify developmentally sensitive periods for substance use in adolescence, and ii) by using genetic data to estimate the causal effect of cigarette and cannabis use on cognition/ emotional processing. Findings have the potential to improve our understanding of harms associated with adolescent cigarette and cannabis use and support the importance of interventions targeting developmental differences in substance use patterns.