"Why Is 'That Person' Prone to Addiction?" — New Research Delves into the Psychological and Genetic Mysteries Behind Cannabis Use

A large-scale GWAS conducted by UC San Diego and 23andMe, published in Molecular Psychiatry on October 13 (Eastern US Time), identified genetic regions associated with the use and frequency of marijuana (cannabis) consumption from the genetic data and surveys of 131,895 individuals. Notably, CADM2 and GRM3 were associated with ever-use, and additional analyses reported 40 new genes (4 genes related to usage frequency). Of these, 29 genes had not been previously reported in cannabis-related traits. These genetic predispositions show correlations with over 100 phenotypes, including schizophrenia, bipolar disorder, impulsivity, executive function, and cardiovascular and metabolic diseases, but do not directly indicate causation. Cannabis use is expanding, with an estimated 64.2 million users in the past year in the US (2024) and 20.6 million estimated to have cannabis use disorder. Experts remain cautious, stating that "clinical application is still far off," while discussions on social media include "caution against genetic determinism," "handling of 23andMe data," and "risks of high-THC products." In conclusion, the image of **“not everyone gets hooked, but genetics have a small influence on susceptibility”** has become more three-dimensional.