Until the turn of the 21st century, most experts thought wasn't addictive. Although most people who smoke cannabis or consume "edibles" don't develop an , recent findings (Budney & Moore, 2014) suggest that about one in ten cannabis users become dependent. Notably, adolescents who start using cannabis before the age of 18 are four-to-seven times more likely (Winters & Lee, 2007) to develop a marijuana use disorder than people who start weed as adults.

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As a teenager in the early-1980s, I smoked a ton of pot. When I started using cannabis, I was a 14-year-old attending boarding school, where smoking weed was an expellable offense. That didn't stop us. My secret society of "stoner" classmates had mastered the art of doing undetectable bong hits in our dorm rooms and masking the odor with Ozium. What started as casual marijuana use on weekends, gradually devolved into a daily "wake-and-bake" habit. After one semester of using marijuana every day, it got to the point where I couldn't face the morning without getting high first. I’d developed a severe case of what is now called "cannabis use disorder" or CUD.

In a strange twist of fate, I had a really bad trip on psilocybin when I was 16. Ingesting a mega-dose (5+ grams) of dried " " spooked me to death and made me scared of drugs. My first psilocybin experience was life-changing in the best ways, however, after one harrowing "psychedelic experience gone wrong," even a tiny hit of pot would instantly trigger "bad trip" flashbacks—which made me insanely paranoid. I haven’t touched cannabis since high school and have absolutely no desire to ever smoke weed again.

That said, based on the findings of a new study (Demontis et al., 2019) on a possible genetic component associated with CUD, I have a hunch that if I were to have genome testing, the results would show expression of a gene variant called "CHRNA2." This paper, "Genome-Wide Association Study Implicates CHRNA2 in Cannabis Use Disorder," was published June 17 in the journal Nature .

For this study, an international team of researchers from the United States, Denmark, and Iceland compared the genomes of 2,000 people who were known to have CUD with genetic test results from another 50,000 people who were not heavy cannabis users. As mentioned, the researchers found a correlation between those who carried the gene variant CHRNA2 and cannabis use disorder.

To double-check the possible link between CUD and CHRNA2, the researchers conducted a follow-up study which used an Icelandic genetic database to compare the genomes of 5,500 people with CUD to genetic data from 300,000 controls. This secondary analysis showed the same CHRNA2/CUD connection as the first phase of the study. As the authors explain, "Analyses of the genetically regulated gene expression identified a significant association of CHRNA2 expression with CUD in brain tissue."

In a statement, the researchers emphasize that having the CHRNA2 gene does not automatically drive someone to become a heavy marijuana user or develop CUD. Instead, having the gene could be viewed as a marker that someone who starts using cannabis is at a higher risk of becoming addicted to cannabis than a CHRNA2 non-carrier who experiments with cannabis.

The researchers speculate that there are probably other associated with cannabis use disorder; CHRNA2 just happens to be the first one they've identified. Hopefully, discovering a link between CUD and CHRNA2 will lead to more research on the genetic aspects of addiction and result in more effective interventions for those struggling with marijuana dependence.