Morin JFG, et al. – Experts assessed the relationships between year-to-year changes in substance use and cognitive development in population-based study. They analyzed data involving 3,826 seventh-grade students from 31 schools—consisting of 5% of all students entering high school in 2012 and 2013 in the Greater Montreal region annually for 4 years—with respect to alcohol and cannabis use, recall memory, perceptual reasoning, inhibition, and working memory, using school-based computerized assessments. They detected common vulnerability effects for cannabis and alcohol on all domains. Cannabis demonstrated lagged effects on inhibitory control and working memory and concurrent effects on delayed memory recall and perceptual reasoning; alcohol consumption did not. Further, cannabis effects were found to be independent of any alcohol effects. In all, adolescent cannabis use showed concurrent and lasting effects on important cognitive functions, which appeared to be more pronounced than those observed for alcohol.