The Yale University–led analysis of the genomes of more than 1 million veterans from the Million Veterans Program focused a spotlight on the underlying biology of cannabis use disorder (CanUD). It also highlighted the condition’s links to psychiatric disorders and abuse of other substances such as tobacco, while also raising the specter of an elevated risk of developing lung cancer.
That is significant to pharmacists because, recently, Georgia became the first state to allow a form of medical marijuana to be dispensed at some independent pharmacies, and other states are expected to follow.
For the study published in Nature Genetics, researchers examined a genome-wide set of genetic variants in veterans from multiple ancestry groups as contained in the Million Veterans Program, one of the world’s largest genetic databases. The researchers incorporated additional information from several other genomic databases.
As a result, the study team identified dozens of genetic variants linked to CanUD and a variety of behavioral and health issues associated with CanUD.
“Once we understand the biology of cannabis-use disorder, we can better understand associated disorders and inform the public of risks associated with marijuana use,” said lead author Daniel Levey, PhD, assistant professor of psychiatry at Yale Medical School and in the department of psychiatry at the Veterans Affairs Connecticut Healthcare Center in West Haven, Connecticut. Joel Gelernter, MD, the Foundations Fund Professor of Psychiatry and professor of genetics and neuroscience, was the costudy leader.
The report pointed out that marijuana is the most commonly used federally illegal drug in the United States, with more than 48 million people (18% of Americans) using it at least once in 2019, according to the CDC.
The authors cited previous research indicating that about one-third of marijuana users develop CanUD, which is defined as a problematic pattern of cannabis use leading to clinically significant impairment or distress.
The findings are evidence that cannabis addiction “could have substantial public-health risks if the usage increases,” Dr. Levey said.
Dr. Levey and his coauthors raised concerns that, as recreational use of cannabis is being decriminalized in many places and medical use widely sanctioned, CanUD will only increase.
“A genetically informed causal relationship analysis indicated a possible effect of genetic liability for CanUD on lung-cancer risk, suggesting potential unanticipated future medical and psychiatric public health consequences that require further study to disentangle from other known risk factors such as cigarette smoking,” the study authors cautioned.
In essence, the study team found that variants of genes that encode for three different types of receptors on neurons were associated with elevated risk for developing CanUD. It also found an association between the variants and the development of lung cancer. The authors explained that more work is required to separate the effects tobacco use and other environmental factors have on cancer diagnoses from those of marijuana use.
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