An analysis of the genomes of more than 1 million people, published Nov. 20 in the journal Nature Genetics, has shed light on the underlying biology of cannabis use disorder and its links to psychiatric disorders, abuse of other substances such as tobacco, and possibly even an elevated risk of developing lung cancer. For the study, researchers examined a genome-wide set of genetic variants in individuals from multiple ancestry groups enrolled in the U.S. Department of Veterans Affairs’ Million Veteran Program, one of the world’s largest genetic databases, and incorporated additional information from several other genomic databases. They were able to identify dozens of genetic variants linked to cannabis use disorder and a variety of behavioral and health issues associated with cannabis use disorder.