Peer reviewed scientific fact, or antiquated scare tactic against cannabis use? The “Gateway Drug” theory has been at the center of the public discourse around cannabis, its safety, and prohibition for decades. So what is a gateway drug and is there any evidence behind the theory?
The gateway drug theory refers to the idea that using a substance — typically marijuana — eventually leads to the use of other, more dangerous substances. In other words, it argues that a teenager may think that marijuana is harmless but it will set them down a path that ends in hard drugs. Claiming it is a clear case of cause and effect, proponents of the theory do not take into account any societal, family, mental health, or cultural factors that may make one more likely to use hard drugs. They also don’t address the notion that correlation does not equal causation.
The Drug Policy Alliance, a non-profit that looks to end the policies of the War on Drugs, states that “research simply does not support the theory that marijuana is a gateway drug.”
Where did the ‘gateway drug’ myth start?
According to the organization, the theory was first introduced by Dr. Robert L. DuPont, Jr., who in his book Getting Tough on Gateway Drugs: A Guide for the Family, proposed that young people who do not use marijuana are relatively unlikely to use other illegal drugs — though he did not say that marijuana causes them to use other drugs.
The organization argues that the book mistook correlation for causation. “Using the same logic, one could argue that drinking milk is a gateway to illicit drug use since most people who use illicit drugs also drank milk as young people,” a DPA policy paper states.
Instead, the organization argues that some people are more likely to try drugs than others, and people who are willing to try drugs are more willing to try multiple drugs. Therefore, because marijuana is the most widely available and used illicit substance in the world, people who have used less popular drugs like cocaine or heroin are more likely to have first used marijuana than those who have not experimented with other drugs.
Or to put it more simply, “people who have used other drugs are more likely to have also used marijuana. Not the other way around.”
‘The majority of people who use marijuana do not go on to use other, ‘harder’ substances’
The gateway drug argument has been used to blur any sort of argument about the potential benefits of marijuana. According to an oped in the Connecticut Post, it has stunted research into the benefits of mariuana and, “as a result, medicinal marijuana is still in a crude phase, failing to reach its potential as an alternative to opioids. Moreover, this vilification led to a war on marijuana, with legal enforcement disproportionately affecting communities of color.”
According to the US government’s National Institute of Drug Abuse, “some research suggests that marijuana use is likely to precede use of other licit and illicit substances and the development of addiction to other substances.”
The institute adds that research has shown that using marijuana put people at greater risk of both alcohol use disorder and of nicotine addiction, and uses a rodent study about dopamine and cannabinoids to assert that “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.”
That said, it adds that while these findings are in line with the view of marijuana as a gateway drug, “the majority of people who use marijuana do not go on to use other, ‘harder’ substances.”
It also admits that other factors such as a person’s social environment, are critical in their risk for drug use and that an alternative theory to the gateway drug hypothesis is that “people who are more vulnerable to drug-taking are simply more likely to start with readily available substances such as marijuana, tobacco, or alcohol, and their subsequent social interactions with others who use drugs increases their chances of trying other drugs.”
What the research says
There is some scientific evidence of a gateway drug effect in more general terms but the substance used isn’t of crucial importance, rather, one must look at when the person first used it. According to a 2016 study in Neuroscience Biobehavioral Review “there is compelling evidence that adolescent drug exposure can induce persisting neural, cognitive, affective and behavioral consequences,” which could potentially lead to further drug use.”
A 2016 study in Preventive Medicine Reports looked at 14 years of data from the National Longitudinal Study of Adolescent to Adult health data, and found that “clearly, marijuana use in early adolescence enhances increased likelihood of continuing use of other psychoactive substances,” but it also stated that it did not find that the proportion of the population using alcohol, tobacco or marijuana in early adolescence showed patterns of increasing use of marijuana, illegal drugs or cocaine according to the length of follow-up (approximately 14 years).“
In addition, it said that anti-drug education should also “assess the underlying mental illness predisposing young people to early drug use.”
A study from 2015 estimated that 44.7% of people with lifetime cannabis use progress to other illicit drug use at some time, but stated that “several sociodemographic characteristics, internalizing and externalizing psychiatric disorders and indicators of substance use severity predicted progression from cannabis use to other illicit drugs use,” and that the greater risk of illicit drug use for cannabis users with mental disorders should be considered when cannabis regulation changes are looked at.
Meanwhile, other researchers have pointed at nicotine as a significant gateway drug, in regard to cocaine use.
The Marijuana Policy Project — a marijuana legalization advocacy group — argued that the gateway hypothesis doesn’t stand up to much scrutiny at all. For one, it mentions that while more than 107 million Americans have tried marijuana, only 37 million have tried cocaine, and 4 million have tried heroin.
While research has shown that marijuana use has increased in some states where it was legalized, in Colorado, Washington, and Oregon — all fully legal cannabis states — opioid deaths are below the national average. Furthermore, a study carried out 2014, found that “Medical cannabis laws are associated with significantly lower state-level opioid overdose mortality rates.” In addition, while the National Survey on Drug Use and Health estimates that in Alaska, Colorado, Oregon, and Washington there is a higher than average level of cocaine use, this was the case in three of these states (Alaska, Oregon, and Colorado) before legalization went into effect.
Though cannabis is seen as largely harmless, people can develop a dependency to it. According to a 2010 study about one in 10 people who use cannabis will develop an addiction, which can entail physical, psychological, and/or social dependence. Physical dependence can include issues such as headaches or weight loss, while psychological symptoms can manifest as anxiety, irritability, and insomnia. Social addiction has to do with the difficulty many users have in stopping or cutting back on their cannabis use in social settings.
Like with other substances, all types of factors can affect one person’s likelihood for developing a dependency, including family history of addiction and mental health issues, among others.
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