In an era when cannabis use is becoming increasingly normalized, both recreationally and medically, a recent study sheds light on the genetic underpinnings of cannabis use disorder (CanUD). Scientists used data encompassing the genomes of over a million people and uncovered DNA segments potentially linked to cannabis addiction.

Cannabis, now legal for recreational use in eight countries and for medicinal purposes in forty-eight, is no stranger to controversy. Despite its supported medical applications for conditions like chronic pain and epilepsy, marijuana is not a silver bullet in medicine as some like to make it out to be. Furthermore, there are important concerns that arise with its addictive potential.

Approximately one in ten cannabis users develop an addiction or use cannabis in a way that hurts them. Previous studies hinted at a genetic angle, while also linking cannabis misuse to various cancers and psychiatric disorders.

To delve deeper, neuroscientists at Yale University expanded upon earlier research by integrating genetic data from varied sources, notably the Million Veteran Program‘s extensive biobank.

The researchers identified significant genetic loci (the location of a gene on a chromosome) linked to cannabis use disorder in various ancestral groups. They found unique genetic factors in European, African, Admixed American, and East Asian populations, suggesting a nuanced influence of genetics on susceptibility to CanUD across different ethnicities.

For instance, a notable locus was identified in CHRNA2, a gene associated with nicotine dependence, in people of European ancestry. Furthermore, SLC36A2 was identified as a significant gene in African populations, which has not been previously linked to CanUD.

These findings also emphasize the importance of including diverse populations in genetic studies, as it allows for a more comprehensive understanding of the genetic factors contributing to disorders like CanUD.

Besides identifying genes that may be involved in addiction, the analysis also found evidence that suggests a bi-directional relationship between excessive cannabis use and schizophrenia, meaning each can potentially exacerbate the other. Multiple previous studies have reached similar conclusions, including a November 2023 study that found that teenagers who use cannabis are at higher risk of schizophrenia and other psychiatric conditions.

Through Mendelian randomization analysis, the researchers suggested a possible genetic link between CanUD and increased lung cancer risk. Further research is required to fully comprehend the full scope and implications of cannabis use for public health.

The findings appeared in the journal Nature Genetics.