In this current age of marijuana decriminalization, both in Canada and the United States, you often hear conflicting claims purporting the addictiveness – or lack thereof – of marijuana. In our contemporary era of hyper-polarized debates, where do you go for reliable information? The answer – your genetic makeup of course!

Three genetic variants linked to marijuana addiction
Like all mind-altering substances, marijuana can be addictive. The degree to which a person is predisposed to become addicted to marijuana can be explained, in part, by that person’s genes.

In an innovative study, scientists detected strong links between variants in 3 genes (RP11-206M11.7, SLC35G1 and CSMD1) and severity of marijuana addiction.

Previously, though such a genetic link was thought to exist, no one knew which specific genes were important for marijuana dependence. Published in JAMA Psychiatry, this research is the first to pinpoint the elements responsible at least partially, for such addiction.

Link between marijuana addiction and other mental illness
In the same study, scientists also discovered intriguing genetic links between marijuana addiction and other mental disorders including schizophrenia and depression.

Scientists explained that this link could reflect common rogue genetic elements that contribute to multiple psychiatric disorders. Or, this could suggest that patients with schizophrenia and depression are actually using marijuana to cope with disease symptoms.

While more studies are needed to draw firm conclusions, evidence for the latter theory is abundant – medical marijuana has been intensely studied for the treatment of many conditions, from appetite stimulation to coping with the side effects of chemotherapy.

Notably, marijuana has been demonstrated to be effective at treating chronic pain, and can be used to supplement or even substitute opioid analgesics. This is welcome news to poor CYP2D6 metabolizers, who can not experience pain relief in response to codeine (e.g., Tylenol 3, Oxycontin or Percocet).

A marijuana predictive test?
New insights into the ways our genes determine medication response are being made everyday.
We may not be far from a future where a simple PillCheckTM test can let you know if you are more likely to use marijuana recreationally, addictively, or as a coping mechanism for another illness.

In the meantime, always remember that even as a “recreational drug”, marijuana use carries risks of addiction and psychosis. Always consult your doctor before taking any substances.

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References:
Agrawal, A., & Lynskey, M.T. (2006). The genetic epidemiology of cannabis use, abuse and dependence. Addiction. 2006 Jun;101(6):801-12.

Karlsson, L.R., et. al. (2019). Genome-wide association analyses of risk tolerance and risky behaviors in over 1 million individuals identify hundreds of loci and shared genetic influences.

Pasman, J.A. (2018). GWAS of lifetime cannabis use reveals new risk loci, genetic overlap with psychiatric traits, and a causal influence of schizophrenia.

Sanchez-Rolge S., et. al. (2019). Genome-Wide Association Studies of Impulsive Personality Traits (BIS-11 and UPPS-P) and Drug Experimentation in up to 22,861 Adult Research Participants Identify Loci in the CACNA1I and CADM2genes.