Many people want a yes or no answer on whether marijuana is a gateway to opioid addiction.
Experts agree it isn't that simple.
“It’s this impossible question to answer,” said Dr. Kevin Gray, professor and director of Child and Adolescent Psychiatry at the Medical University of South Carolina.
At a recent lectureship hosted by MUSC, experts touched on the causes and solutions of the opioid epidemic. One of topics included a discussion of whether marijuana is a gateway drug leading to opioid use.
The general consensus: There needs to be more research.
“The reality is that these things are complicated," said Gray, who attended the discussion.
For long time the United States has been in the midst of an opioid epidemic. In 2017, the Center for Disease Control and Prevention reported that most of the more than 70,000 drug overdose deaths involved opioids. For the same year, the National Institute on Drug abuse reported nearly 750 opioid deaths in South Carolina.
In the middle of this epidemic is also a discussion on what factors cause opioid addictions. This includes cannabis use. Columbia University Clinical Psychiatry professor Arthur Robin Williams and columnist Jacob Sullum both led the discussion at the MUSC lectureship on the cannabis gateway topic.
Williams presented information that suggested there was a possible gateway. Sullum held the opposite view.
Both agreed there isn’t enough research to definitively say whether marijuana is a gateway drug for opioid use.
Williams explained that the most valuable form of research would be incredibly invasive. It would likely involve exposing randomized adolescents to cannabis long-term and comparing them to a group exposed to a placebo.
With that, experts could directly observe the likelihood of opioid addiction.
“Find a parent who’s going to agree to that,” Williams said.
Gray said, “It would be unethical.”
Gray and Williams suggest that the closest the public could possibly come to that information is with broader studies. An example they highlight is the Adolescent Brain Cognitive Development Study by the National Institute of Health.
The project is hoping to examine adolescents long term, to understand how they grow. The ultimate goal is to get a better feel of healthy adolescent development.
The study involves 21 institutions, including MUSC. Gray is one of the principal investigators for the study, which will highlight things such as family history and environmental factors. One possibility with the study is to highlight adolescents exposed to cannabis.
With that there is the potential to get some information on a correlation. But it probably won’t be enough to provide a definitive answer. The results would highlight correlations and not necessarily a singular cause of opioid addiction.
Gray suggests that one problem is the gateway question itself.
“It’s framed too much as a black-and-white and yes-or-no issue,” he said. “There are shared vulnerabilities with substance use.”
Many experts agree there are often a lot of factors that feed opioid addiction. Most of those factors involve circumstances that may be out of a person’s control.
The type of environment a person is raised around can increase the likelihood of opioid addiction. Genetics could potentially play a role as well. Williams compared the genetic component to what is seen with cancer.
“You’re more likely to have cancer if you have a (family) history of cancer,” he said.
He explained the same can be said for addiction. If a person has a family history of opioid addiction, then that could increase their likelihood of being an addict.
He and Sullum also noted trauma and accessibility could be a factor.
So the likelihood of marijuana being a direct gateway to opioid addiction is a bit far-fetched Gray said.
“It’s probably more likely that there may be some shared risk,” he said.
Some of the confusion comes in with the coincidental use of both cannabis and opioids. Gray emphasized most opioid addicts have noted past marijuana use. But he also explained there are plenty of people who used marijuana that didn’t go on to use opioids.
“We know a lot of teenagers experiment with substances and do okay," he said.
In the 2017 National Survey on Drug Use and Health, it noted that more than 90 percent of illegal drug users noted past marijuana use.
Sullum said, “You have these very clear correlations, but you have no idea what they mean."
There have also been studies with other drugs that fed the possibility of a gateway.
Williams referenced a past study that used mice to observe the relationship between nicotine and cocaine.
In the study there were mice that were exposed to nicotine and there were some that were not. All of the mice were exposed to cocaine. The study found that the nicotine exposure directly impacted the effect of the cocaine. The nicotine-exposed mice moved faster.
Additional research has also suggested that nicotine reinforces the seeking and consumption of drugs.
Scientifically, there needs to be more research on the cannabis gateway question. But experts have made arguments that there may be just a cultural relationship between cannabis and opioids.
Sullum explained that people purchasing marijuana in states where it’s illegal are probably able to get opioids the same way. He also sighted studies that found that states with medical marijuana laws saw reductions in high-risk opioid use, opioid-related hospitalizations and treatment admissions for opioid use disorder.
Sullum and Williams both agree that there still needs to be more research on states with recreational marijuana laws.
“These debates are challenging to parse because sometimes there won’t be a quick and obvious answer,” Gray said.
Though the gateway question needs more information, Gray says the public should be mindful of adolescent risks. He said though experts don’t know if cannabis is a definitive gateway to opioids, they do know marijuana can be harmful in early exposure.
Past studies have suggested that frequent use of marijuana early in adolescents directly impacts brain development. Like with the gateway question, some experts note that more research is needed.
But Gray said that doesn't mean there should not be debates on these impossible questions. “These debates are helpful to highlight these complex issues.”