Cannabis use disorder may be influenced by genetics

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People who develop a cannabis use disorder share certain genetic markers, and that pattern holds across racial groups, according to the largest study of its kind.

Around one-third of people who self-identify as regular cannabis users will go on to develop cannabis use disorder the continued, regular use of the drug despite a negative impact on ones life. People with cannabis use disorder often find it difficult to quit the drug and need higher and higher doses to feel an effect.

Its possible that you could be only a weekend user and still meet the criteria for cannabis use disorder, but its pretty unlikely, says Joel Gelernter at the Yale School of Medicine. These are mostly much more frequent users.

The genetic link to problematic cannabis use has been explored before, but this latest research is the first to look at a large sample across different racial backgrounds. Researchers combed the genetic information of more than 1 million individuals registered in the Million Veteran Program, which collects data from military members in the US. Their sample included a range of ancestry groups, such as European, African, East Asian and mixed race. Then, using a technique called genetic correlation, they compared variations in each persons DNA to see if these were associated with a certain trait: in this case, cannabis use disorder.

We found that the pattern was very close to identical across the different ancestries, says Dan Levey, also at the Yale School of Medicine. They compared variations in each persons DNA and found that some were associated with a certain trait. For example, in people with European ancestry, strong expression of a neuronal receptor called CHRNA2 was associated with a higher risk of developing cannabis use disorder.

The researchers also analysed health records and found a link between lung cancer and developing cannabis use disorder for those with European ancestry, even when controlling for cigarette use. Gelernter says that, as a result, we may see a rise in lung cancer cases which often take years to diagnose alongside the rise in the popularity of cannabis. If smoking pot does lead to increased risk for lung cancer, the uptick wont be observable until decades from now, says Gelernter. This is something that people should be on the lookout for.

As the use of marijuana and its compounds rises around the world, New Scientist explores the latest research on the medical potential of cannabis, how it is grown and its environmental impact, the way cannabis affects our bodies and minds and what the marijuana of the future will look like.

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Cannabis addiction may be partly down to genetics - New Scientist