Over the years, cannabis has been at the center of much misinformation—most of it negative. The fearmongering came to a peak in the 1930s with the release of “Reefer Madness,” an American propaganda film that depicted high school students engaging in all sorts of criminal activities—manslaughter, attempted rape, and a hit and run, to name just a few—after consuming cannabis.
Since then, society’s views on cannabis have slowly shifted. This is thanks in no small part to a better understanding of the plant’s medical benefits. Nevertheless, some myths about marijuana persist to this day, including the widespread belief that cannabis is a gateway drug that leads to harder, more dangerous substances.
Is there any truth to this claim? Not so much, according to a number of well-researched studies.
Understanding the Gateway Drug Theory
In a nutshell, the gateway drug theory is the notion that consuming marijuana will increase the probability of a person using other types of drugs in the future. Proponents of the theory say that drug use actually changes the brain, so the user is more likely to consume other, stronger drugs down the line. They also cite statistical probability that first-time drug use is the beginning of a trend.
On first glance, one study out of the University of Cagliari in Italy seems to confirm this. In their investigation, researchers set out to explore the effects of cannabinoids on the brains of adolescent rodents.
They found that neurons in the mesolimbic dopamine system became significantly less responsive after being subjected to the cannabinoid agonist WIN—a chemical that produces very similar effects to tetrahydrocannabinol (THC). According to the National Institute on Drug Abuse, “...this could help explain the increased vulnerability for addiction to other substances of misuse later in life that most epidemiological studies have reported for people who begin marijuana use early in life.”
While the University of Cagliari may offer some scientific insight into the biological mechanisms of cannabis, it’s more likely that other factors are to blame for the correlation between cannabis and other illicit drugs. This is because animal studies aren’t affected by peer groups, socioeconomic factors or other societal issues that humans face.
What Do Other Studies Say About Marijuana as a Gateway Drug?
There’s a lot of research that shows a significant relationship between cannabis and hard drug use. For example, a 25-year study—one of the longest of its kind—published in the scientific journalAddiction found that regular or heavy cannabis use was linked to an increased risk of abusing and/or becoming dependent on other illegal drugs.
Meanwhile, investigations such as this report from the Centers for Disease Control and Prevention in the United States indicate that people who are addicted to cannabis are three times more likely to be addicted to heroin.
So, according to these figures, there certainly seems to be a link between cannabis and hard drugs. But does this association mean that cannabis consumption actually causes a person to use other drugs?
The Verdict: Cannabis Can’t be Considered a Gateway Drug
Although there's a fair amount of evidence showing an association between cannabis use and illicit drugs, there’s little to suggest a causal link. Many scientific studies show the gateway drug theory is highly unlikely, or even impossible to prove.
Researchers point to issues like the influence of social circles that could explain why some marijuana consumers move on to other substances. In a study published in Drug and Alcohol Review, researchers explained that being part of a social circle that uses cannabis may pave the way for future opportunities to use other illicit drugs. It may also cultivate a favourable attitude toward other such drugs. Another factor is that some people may have certain traits that make them more disposed to consuming cannabis and other types of drugs.
While these factors are real, it doesn’t prove that cannabis causes people to experiment with other substances. In fact, the average person doesn’t move on to hard narcotics after consuming cannabis. If marijuana truly were a gateway drug, then nearly everyone who consumes cannabis would also consume other drugs, and that’s just not the case.
We can see clear evidence of this in regions that have recently allowed the use of cannabis. For example, a recent study from LiveStories examined drug use trends following the legalization of cannabis in Colorado, Washington, Oregon and Alaska. None of the states experienced a significant increase in the use of alcohol, tobacco, cocaine or heroin.
"The hypothesis was that if marijuana is truly a gateway drug, we'd see a spike in the use of other substances in addition to a spike in marijuana use," said LiveStories founder Adnan Mahmud, speaking with Denver-based independent newspaper Westword. "We should have seen spikes all over the place. But when we looked at the data, the corresponding spikes didn't exist. And because of that, it led us to the conclusion that there isn't a strong correlation between marijuana use and the use of other substances."
Marijuana as an Exit Drug
Not only is cannabis not a gateway drug, it could even be considered an “exit drug.” Research published in the Journal of Pain found that many patients are using medical cannabis to replace more harmful opioid medication. Almost two in three (64%) of the study’s participants were able to use medical cannabis to decrease their opioid use.
So, the bottom line is that cannabis isn’t a gateway drug. It may be associated with an increased risk of using hard drugs, but research indicates that this link is a matter of correlation, and not causation.
Photo credit: Esteban Lopez