This complex analysis suggests that cannabis use by teenagers may have an ongoing effect on their brain function, particularly in the areas of:

working memory (important for completing tasks) perceptual reasoning (important for understanding the world) inhibition control (important for learning to resist harmful impulses) The main difficulty is that we still don't know with certainty whether teens who used alcohol and cannabis had worse brain function because of substance use, or whether they were more likely to use alcohol and cannabis because of their poorer brain function.