A common theory promoted by people who oppose marijuana legalization is that the consumption of marijuana leads to the use of harder drugs, such as cocaine and heroin.
People who use the so-called gateway drug theory as a reason to protest the legalization of marijuana point to trends and data they see as supporting the theory. But does the evidence they rely on really show that marijuana is a gateway drug?
Correlation does not imply causation. Two things occurring together does not mean that one of those things causes the other thing to occur. Instead, the science and medical communities point to environmental factors, not marijuana, as potential gateways to hard drug use.
The Gateway Drug Theory
Let’s start by reviewing the specifics of the gateway drug theory (also called the stepping-stone theory, progression hypothesis, or escalation hypothesis). As stated, the gateway drug theory posits that the use of a psychoactive drug, such as marijuana, is linked to an increased risk of trying harder drugs. The theory suggests that the escalation in drug use from marijuana to, say, heroin is due to factors that include biological alterations and a similar attitude about drug use.
In certain lab tests, early cannabis use in rats increased the likelihood that the rats would self-administer nicotine, morphine and heroin (1) later in life. Test indications showed that anatomical changes in the rats’ brains’ reward system occurred as a result of the earlier cannabis consumption. Similar results were found when rats were exposed to nicotine early in life, rather than cannabis. However, lab tests on rats do not prove causation, nor are they conclusive relative to humans. They merely reflect sequence. Again, correlation does not imply causation.
Proponents of the gateway drug theory believe that similar attitudes about illicit drug use among peers may lead to an increase in a person’s interest in experimenting with certain drugs, including marijuana. Environmental and personal factors, such as social and economic conditions, (including exposure to cannabis and nicotine early in life), may lead to use.
However, in human twin studies where one twin reports drug use while the other twin does not, the impact that familial exposure to cannabis at a young age may have on a person’s decision to try it is debunked (1). In fact, other studies suggest that strong family ties help dissuade people from using illicit drugs (12).
Other environmental factors, including association with different peer groups, may impact a person’s attitude about marijuana and other harder drugs, but that doesn’t make marijuana a gateway. In summary, pointing to environmental factors does not make marijuana a gateway drug. Instead, the environmental factors themselves may serve as the gateway.
Marijuana: Scope of Use, Effects, and Possible Dangers
What is Marijuana?
Marijuana is a mixture of flowers yielded from the Cannabis sativa plant. It is a versatile plant that, in its many forms, can be consumed using a variety of methods, including smoking, eating, vaporizing, and drinking (2). Common marijuana consumption forms include the following:
- Smoking: joints, cigars, bongs, pipes.
- Eating: Bakery goods, candy, butter.
- Vaporizing: hash oil, shatter, liquid resin.
- Drinking: tea, oil, marijuana leaves.
Marijuana’s primary psychoactive element is delta-9-tetrahydrocannabinol, more commonly known as THC. The female cannabis plant, specifically its leaves and buds, is where most of the plant’s THC is found. However, the cannabis plant also contains in excess of 500 additional chemicals, including more than 100 THC-related compounds. These are called cannabinoids (2).
Scope of Marijuana Use in the US
According to the 2016 National Survey on Drug Use and Health (3), marijuana is the most widely used illicit drug in the United States. The survey, sponsored by the Substance Abuse and Mental Health Services Administration (SAMHSA), represents the most current information available. The survey also provided the following data about marijuana consumption:
- Of the 28.6 million people aged 12 years and older who used illicit drugs in 2016, 24 million of them were marijuana users (3).
- The figure represents 8.9 percent of the United States population of people aged 12 and older (3).
- 6.5 percent of adolescents (1.6 million) between 12 and 17 used marijuana in 2016 (3).
- 20.8 percent of people (7.2 million) aged 18 to 25 used marijuana in 2016 (3).
- 7.2 percent of people 26 and older (15.2 million) used marijuana in 2016 (3).
The 2016 survey notes that the percentage of marijuana used in 2016 among people 12 years of age and older was higher than the use for the same collective group between the years of 2002 and 2015 (3). However, use among those in the 12 to 17-year-old sub-group was lower than in some of the previous years, according to the survey. The downward shift in youth marijuana usage may be related to legalization, which will be discussed later in the article.
Effects of Marijuana Use
When smoked or vaporized, the effects of marijuana are felt almost immediately. Many people report a sense of euphoria, anxiety reduction, happiness, a feeling of relaxation, and calm (4). The effects of smoking marijuana can last roughly one to three hours.
When marijuana is eaten or used in drinks, the effects may take longer to surface. Generally speaking, it may take 30 minutes or as long as one hour before the effects are realized. As a result, some people may ingest more marijuana than was intended (4). The effects of eating or drinking marijuana can last longer than when it is smoked.
Marijuana may also cause people to feel hungry, and that may be beneficial for those suffering from certain conditions or taking medication that prevents them from wanting to eat.
Possible Dangers of Marijuana Use
Marijuana impacts each person differently. The type of marijuana ingested may also alter the experience for those who typically do enjoy it. Negative side effects of consuming marijuana may include panic, anxiety, and fear (4). People who ingest too much marijuana may also experience hallucinations and delusions or a temporary loss of personal identity.
Operating vehicles while under the influence of marijuana is illegal, as it is considered driving while intoxicated, just like with alcohol. Detectable traces of THC may stay in the body for several weeks, long after its psychoactive effects subside. So, people who are stopped for traffic violations may test positive for THC, even if they haven’t smoked marijuana recently.
Marijuana Is Not a Gateway Drug
People who have used marijuana do sometimes go on to use harder drugs, such as cocaine or heroin. Anti-marijuana proponents use that information as proof that marijuana is a gateway drug. However, of the tens of millions of people in the United States who have tried marijuana, only a fraction of them have used harder drugs.
According to the SAMHSA survey, 28.6 million Americans in total used illicit drugs in 2016, with 24.0 million of those users citing marijuana as the drug they consumed (3). That means that approximately 4.6 million people used illicit drugs other than marijuana, with many of those people likely never using marijuana at all. As the numbers clearly show, the use of marijuana does not appear to cause people to turn to illicit drugs, which includes both legal and illegal narcotics.
What Do the Science and Medical Communities Say About Marijuana Being a Gateway Drug?
The United States science and medical communities have been studying marijuana as a potential gateway drug since at least 1938, when “The LaGuardia Report” was commissioned by New York City Mayor Fiorello La Guardia. Released in 1944, the six-year study found that marijuana does not lead to the addiction of harder drugs. The report notes, “… instances are extremely rare where the habit of marijuana smoking is associated with addiction to these narcotics.” (6)
Fast forward to 1972, when President Nixon commissioned an expert panel to examine the federal policy on marijuana. In part, the addiction scholars evaluated whether marijuana was a gateway drug. The panel concluded that relative to marijuana smoking, “… the incidence of other drug use was relatively low, [even among] frequent marijuana users.” (6)
The Institute of Medicine released a report in 1999 that covered a myriad of aspects of marijuana, including whether or not marijuana is a gateway drug. The institute indicated that no conclusive evidence exists to support the notion that marijuana’s drug effects are connected to the abuse of other drugs. Additionally, the Institute of Medicine explained, “Patterns in progression of drug use from adolescence to adulthood are strikingly regular. Because it is the most likely used illicit drug, marijuana is predictably the first illicit drug most people encounter. Not surprisingly, most users of other illicit drugs have used marijuana first. In fact, most drug users begin with alcohol and nicotine before marijuana – usually before they are of legal age.” (6)
Studies conducted by other notable organizations, including the RAND Corporation, the Centre for Economic Policy Research, London, and the National Institute of Mental Health, all reached similar conclusions. In short, the worlds of science and medicine continually conclude that marijuana is not a gateway drug.
Marijuana May Help Combat Hard Drug Use
Not only has science shown over and over that marijuana is not a gateway drug, but empirical evidence strongly suggests that marijuana can act as a buffer for those who are trying to stop using harder drugs, including opioids. In other words, marijuana may help, not hinder, when it comes to combatting drug addiction.
Medical Marijuana and Opioid Addiction
The Journal of the American Medical Association published a report in October 2014 (9) that studied the impact of state medical cannabis laws and how they impact opioid mortality rates. The study, which covered the years between 1999 and 2010 and included all 50 states, found that states that legalized medical cannabis “… had a 24.8% lower mean annual opioid overdose mortality rate compared with states without medical cannabis laws.” (9)
Medical Marijuana and the Reduction of Prescription Medications
A review of New England’s medical marijuana dispensary members concluded that prescription drug use is reduced when medical marijuana laws are passed. (10) Reductions in use among those polled included the following drugs and percentages:
- Opioids: 76.7%
- Antidepressants: 37.6%
- Anti-anxiety medication: 71.8%
- Migraine medication: 66.7%
- Sleep medication: 65.2%
Respondents of the New England medical marijuana dispensary survey also reported a reduction in alcohol use of 42%. Please note that additional research needs to be conducted to confirm these findings.
Cannabis and Crack Cocaine Cravings
It seems that marijuana may have the opposite effect of a gateway drug when it comes to crack cocaine. Between 2012 and 2015, the University of Montreal and the University of British Columbia collected data from people who used marijuana to try to control their cravings for crack cocaine. The efforts paid off, as 122 participants reported that consistent cannabis use did help curb their desire for crack. (11) The information is especially important, given that there are currently no pharmacotherapies that effectively help in the treatment of crack cocaine addiction. (11) Further research is needed, though.
Factors That Act as a Gateway to Hard Drug Use
Marijuana may not be a gateway drug on its own, but some marijuana users eventually do move on to using harder drugs. So, what are the factors that lead to the jump from a drug like marijuana to a potentially life-ending drug like heroin, for example? As it turns out, there are several factors at play.
Poverty and Social Environment
A lack of education and meaningful social relationships are strong indicators of potential drug abuse, according to research from the National Institutes of Health (12). Familial and job commitments make it less likely that a person will engage in self-destructive behaviors, including illicit drug use and violent crime. Without those positive motivators, hard drug abuse is more likely.
People who do not have high school diplomas are less likely to have meaningful employment, and those who do work often earn far less than their more educated peers. As a result, less educated individuals tend to live in more urban, low-cost areas. Living in the confines of concentrated poverty and seeing people who sell and use drugs in order to cope with their surroundings may contribute to the decision of new users trying harder drugs (12). This may be especially true for those who are not held accountable by family (a spouse or children) or other responsibilities.
Association with People Who Use Hard Drugs
The environment users surround themselves in is more likely to lead people to use harder drugs. One example of this has to do with the fact that marijuana is still illegal to purchase in most states. So, people who want to purchase cannabis must get it from an illegal source (5). People engaged in the illegal marijuana drug trade may also sell harder drugs, and/or they may be surrounded by others who sell and use harder drugs as well.
As a result, marijuana users are exposed to harder drugs and the people who use and sell them. When marijuana users are in the company of such drugs and people, some of them may choose to try life-threatening substances. Without exposure to such individuals, the likelihood of seeking out harder drugs is reduced. So, doesn’t it make sense that the legalization of marijuana may reduce the use of these substances since people who purchase marijuana from a dispensary are less likely to encounter such negative environmental factors?
Certain Mental Illnesses
The National Institutes of Health reports that certain mental illnesses predispose people to addiction. Specifically, people who suffer from illnesses along the bipolar spectrum are at an increased risk for substance abuse (13).
Generally speaking, the National Institute on Drug Abuse advises that people who suffer from even mild mental disorders may self-medicate by abusing illicit drugs. Additionally, mental illnesses and drug use disorders share overlapping factors that may include genetic vulnerabilities, brain deficits, and early trauma exposure (13).
Criminalization and Prohibition
According to the Drug Policy Alliance, recent reports show that recreational marijuana drug use among teenagers actually decreased in states where marijuana is approved for medical use. Since marijuana is no longer considered to be forbidden or taboo, it doesn’t appeal to young people like it used to (15).
Additionally, young people may use marijuana less, because the law requires users who purchase it in stores to be 21 years of age and older. Some states allow people as young as 18 to buy marijuana if they possess a valid medical marijuana card.
While young people may still buy marijuana from illegal dealers, legalization efforts have moved sales from the unregulated streets to the legal dispensaries, making illegal sales less profitable and illegal marijuana less available.
Most of the research linking marijuana to harder drug use comes from the correlation between the two. However, as any junior scientist can tell you, correlation does not mean causation. When analyzing what acts as a “gateway” to hard drug use, there are a number of factors at play.
According to the Marijuana Policy Project, more than 107 million Americans have tried marijuana. That’s over 40% of the United States’ population born since 1960 (7). Compare that with the total of 37 million who have tried cocaine and the four million who have tried heroin (7), and it’s clear that other factors are at play.
Opponents of marijuana attempt to demonize it by erroneously connecting the relationship between cannabis use and harder drugs. Fortunately, the science and medical communities have decades of research that indicate marijuana is not a gateway drug.
Frequently Asked Questions
Is marijuana a gateway drug? Why or why not?
The science and medical communities agree that other factors, including one’s environment and mental disorders, appear to serve as the gateway to harder drugs.
What is a gateway drug?
A gateway drug is one that may lead to the use of other harder drugs.
Do we have solid evidence that marijuana is not a gateway drug?
Studies show that the vast majority of people who use marijuana do not springboard into using harder drugs. Studies also show that other factors, such as one’s socio-economic environment, the lack of marijuana legalization laws, and mental disorders, are more likely to serve as gateways.