A recent study from Yale took a close look at people who have specific, in common genes that may give them their cannabis dependence (CAD). Dr. Joel Gelernter, a psychiatrist at Yale who is also a senior author of the study, told The Daily Beast, “We showed that risk for cannabis dependence is affected specifically by certain risk alleles and these risk alleles fit biologically with some of our existing ideas of the nature of cannabis dependence."
A group of 15,000 people, all with different dependence issues, were sampled to see if there were correlations between certain addictions and genes. 18 percent to 36 percent of them were addicted to cannabis, 10 percent higher than the real world population with CAD. In addition to sharing a gene linking to this kind of dependence, the scientists also found something else out—and something pretty jarring.
"We also showed that genetic predisposition for cannabis dependence overlaps with genetic predisposition for major depression and schizophrenia," Dr. Gelernter said. In addition to this, Dr. Gelernter also stated that this finding supports a previous one, one from way back in 2002 that shows a relationship between people who suffered from cannabis dependency and had some sort of psychiatric disorder. 90 percent of people, actually.
Nevertheless, as pointed out in the comprehensive Daily Beast piece, all of this information should still be taken with a grain of salt. "Substance use and other psychiatric illnesses may share common genetic risk factors," but it's important to note that the Yale authors agree that "self-medication, or confounding by other factors may explain their co-occurrence."
Despite these findings, Dr. Gelernter and his team also want to make known that their research shouldn't have too much of a bearing on future legislation. “These results don’t really bear directly on arguments about the harm caused by marijuana or the advisability of legalization." Our study is more related to a different kind of idea—that some people, if they use marijuana, are biologically at higher risk of eventually becoming dependent, than other people.”
Regardless, it's good to know there are some breakthroughs that may explain why certain people are more inclined to smoke marijuana and develop an attachment to the substance. If anything, for those in favor of legalization, this should allow for more responsible, thoughtful action.