directions of association with lifetime cannabis ever-use. We also found that genetic liability for cannabis use disorder is associated with increased risk of mental health problems, infectious diseases, and respiratory illnesses in a large independent sample. Finally, we found a significant association between increased polygenic liability for cannabis use disorder and low white matter volume in cannabis-naive children, suggesting a potential role of cannabis-related genetic predisposition in early brain development.Implications of all the available evidenceCannabis use disorder is a psychiatric illness that is genetically associated with many negative outcomes (including increased risk of psychiatric disorders and respiratory illnesses). Lifetime cannabis use and cannabis use disorder show at least partially divergent genetic influences and associations with relevant traits. Given increasingly permissive cannabis laws and positive perceptions of its safety, the recognition that cannabis use disorder is a serious psychiatric illness should spur prevention and treatment efforts.
