Is marijuana a gateway drug?Medical studies have yet to show cause-effect between early pot use and hard drug use later

  • Police confiscated $2,435 in cash, as well as animal tranquilizer ketamine and drug paraphernalia, during an arrest at the StrangeCreek Campout music festival in Greenfield. Contributed photo


  • Items seized as evidence from a drug arrest in Greenfield one weekend. RECORDER FILE PHOTO

  • OxyContin pills are arranged for a photo at a pharmacy in Montpelier, Vt. on Feb. 19, 2013. Drug overdose deaths rose for the 11th straight year, federal data show, and most of them were accidents involving addictive painkillers despite growing attention to risks from these medicines. As in previous recent years, opioid drugs — which include OxyContin and Vicodin — were the biggest problem, contributing to 3 out of 4 medication overdose deaths. AP FILE PHOTO

Recorder Staff
Published: 10/31/2016 12:35:10 AM

Is marijuana actually the “gateway” to harder drug use that some say it is?

It’s a prospect that opponents of Question 4, which would legalize marijuana in Massachusetts, worry about, especially in the midst of a deepening national opioid and heroin abuse crisis.

But proponents of Question 4 in Nov. 8’s election say those concerns are overblown. In fact, they say, legal marijuana would be safer and easier to buy and could even provide an alternative to hard drugs and keep pot smokers away from those who peddle more lethal wares.

The theory is that as people begin to use marijuana and enjoy its intoxicating effects, they might eventually begin to seek out other drugs that could get them even higher — like heroin, or cocaine — and become addicted.

No causal link shown yet

But the research done so far on a link between marijuana use and later hard drug use is inconclusive. Though dabbling in marijuana does tend to precede and make one more likely to engage in hard drug use, such a correlation doesn’t necessarily mean it causes those problems down the road, studies have found. Some studies have also found similar correlations between tobacco and alcohol use and future hard drug problems.

Mark Kleiman, a professor of public policy who studies drug policy at New York University, said the answer to the question is “a clear ‘Maybe.’”

“It’s true that if you’re looking at a group of 15-year-olds who may get in trouble with drugs other than cannabis, knowing which are using cannabis now would be useful to see if there’s a positive correlation between using at early ages and winding up using other drugs later,” Kleiman said. “One version would be causal — that somehow using pot gets you into other drugs.”

But, Kleiman said, there’s another explanation: some kids are just interested in drugs. He used an analogy: “If I find some kid abusing Coors (beer) is also abusing Michelob, it’s not because Coors is a gateway, it’s because kids that like beer, like beer,” he said.

Kleiman said the data’s not totally clear on which scenario is the case, but he said research in the short run has actually proven that areas where marijuana is less restricted tend to see less abuse of opioids — the pharmaceutical painkillers widely considered to have sparked off a national heroin addiction crisis in recent years.

“We do know in the short run, cannabis tends to be a substitute for, not a complement to, opiates,” he said. “If they have access, they’ll use cannabis instead of opioids as a pain reliever, or use some with them and therefore take less (opioids).”

Study finds link, but ...

A 2006 study out of the Christchurch School of Medicine and Health Sciences in New Zealand found a link between marijuana use and risk of dependence on other drugs, but stopped short of saying it was the direct cause of that behavior.

That study, led by Professor David Fergusson, tracked the health development and adjustment of 1,265 New Zealand children over 25 years.

“Regular or heavy cannabis use was associated with an increased risk of using other illicit drugs, abusing or becoming dependent upon other illicit drugs, and using a wider variety of other illicit drugs,” the study showed. “The risks of use, abuse/dependence, and use of a diversity of other drugs declined with increasing age. The findings may support a general causal model such as the cannabis gateway hypothesis, but the actual causal mechanisms underlying such a gateway, and the extent to which these causal mechanisms are direct or indirect, remain unclear.”

Gateway issue complex

Fergusson in an email interview said the gateway drug theory is a complex topic that is often misrepresented in popular debate, and could be explained in more than one way.

“First, it may be suggested that early cannabis use may change the brain chemistry of young people so that they are more susceptible to using other illicit drugs. Second, it may be suggested that the pleasurable effects of cannabis use may stimulate young people to experiment with other types of illicit drug,” Fergusson wrote. “Third, it may be suggested that the association is due to the illegal status of cannabis which results in young cannabis users having to associate with drug using peers and drug dealers. This differential association may act to increase the likelihood that the young cannabis users will come into contact with and use other illicit drugs.”

Fergusson said the best response to concerns about marijuana as a gateway drug is to recognize the possibility in legislation by setting a 21-plus purchase age, creating strong penalties for supplying the drug to underage users, and gradually phasing in changes to the legality of marijuana rather than making rapid changes to the laws.

The National Academy of Sciences’ Institute of Medicine found in a 1999 study that using one drug makes using other drugs more likely, but said other social and behavioral factors are at work, too, and did not establish a direct causal link either.

“Because it is the most widely used illicit drug, marijuana is predictably the first illicit drug that most people encounter. Not surprisingly, most users of other illicit drugs used marijuana first,” the report said. “In fact, most drug users do not begin their drug use with marijuana — they begin with alcohol and nicotine, usually when they are too young to do so legally.”

Risk for youth

The study also found that those who use marijuana more regularly are more likely to use other substances than those who use occasionally, as are those with existing psychiatric disorders. It also attributed marijuana’s illegality itself as a social factor in introducing users to other substances — harder drugs circulate the same markets.

“In the sense that marijuana use typically precedes rather than follows initiation into the use of other illicit drugs, it is indeed a gateway drug,” the report read. “However, it does not appear to be a gateway drug to the extent that it is the cause or even that it is the most significant predictor of serious drug abuse; that is, care must be taken not to attribute cause to association. The most consistent predictors of serious drug use appear to be the intensity of marijuana use and co-occurring psychiatric disorders or a family history of psychopathology, including alcoholism.”

Kleiman, the New York University professor, said the main effect from increased marijuana use he worries about is the potential for it to increase nicotine and tobacco use, particularly through vaporization devices, and the effects more marijuana use would have on the educational outcomes of youth.

“That’s much more of a concern than the gateway effect that may or may not be there,” he said.”

You can reach Tom Relihan at:
413-772-0261, ext. 264
On Twitter, @RecorderTom


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