Key takeaways:
Marijuana has long been considered the leading gateway drug, meaning that using it leads to other drugs.
Research shows that marijuana may have a gateway effect for adolescents. However, it’s not proven to act as a gateway drug to other substances for everyone.
Your chances of going on to use harder drugs than marijuana depend more on your life situation.
Marijuana has carried the reputation of a gateway drug for decades. But does marijuana use always lead to harder drugs?
The gateway drug theory draws a straight line between marijuana and powerful drugs like heroin and opioids. Current research reveals a more complex connection. We’ll start by understanding the origins of the gateway drug theory.
Gateway drugs: Definition and origin
A gateway drug is easy to get and perceived to be less dangerous. People who try substances often begin with marijuana, alcohol, or tobacco. Let’s look into the gateway drug theory and the substances people use.
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The gateway drug theory
The gateway drug theory is based on studies in 1975 about substance use history. These studies became the basis for the gateway drug theory. Research during that era suggested that people progressed from gateway drugs to harder substances. This remained the leading theory for many years despite disagreement about this interpretation.
The gateway drug theory suggests that a person tries less harmful substances first. This primes their brain and body to seek harder, more dangerous drugs. The term “gateway drug” became a catchphrase for alcohol, marijuana, and tobacco.
Marijuana and cannabis are often used interchangeably, but there are differences. Cannabis refers to the broader group of plants that include hemp and marijuana. Marijuana has significant amounts of THC, the ingredient that creates a high.
Marijuana designated as the ‘gateway drug’
Marijuana has long been considered the leading gateway drug. In 1936, a film called “Reefer Madness” was released. It was an anti-marijuana propaganda film aimed at worried parents. The film promoted the idea that marijuana caused teens to have sex and commit crimes.
The Marijuana Tax Act of 1937 soon criminalized the use and possession of marijuana. The gateway drug theory put a spotlight on marijuana again in the 1980s.
Marijuana use is on the rise, especially for teens and young adults. Most try any substance for the first time between ages 16 and 17. One study showed that teens are now trying marijuana at a younger average age than tobacco and alcohol. Despite being legalized in many places, marijuana is the most widely used illicit substance in the United States.
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A closer look at gateway drug use statistics
Alcohol: In the U.S., teens use alcohol more than any other substance. About a quarter of teens ages 14 to 15 have had at least one drink.
Tobacco: Teen tobacco use is declining overall, but vaping has kept the rate high. As of 2020, 24% of high school students use some type of tobacco product.
Opioid pain medication: Opioid painkillers can have a gateway effect for heroin. Painkillers are controlled substances and heroin is illegal. But they have similar chemical properties, making the gateway connection more direct. A person misusing opioids is 40 times more likely to develop a heroin addiction.
Is marijuana proven as a gateway drug?
The gateway theory cannot be proven for marijuana or any other substance. There are links between early marijuana use and more harmful drug use later on. But that doesn’t mean marijuana use itself is the cause. We’ll explore these links and another theory that offers another explanation.
Gateway drug theory is up for debate
The gateway drug theory was widely accepted when it first came out. But it has not held up to the scrutiny of additional research. There are connections between marijuana use and other substances. But they are more complex than a simple gateway sequence.
One study reviewed health data spanning 14 years from adolescence to adulthood. Researchers concluded that the connection between marijuana use progression to harder drugs was inconsistent. Researchers from another study looked at risk factors for developing substance use disorders. They found that the sequence of substance use didn’t contribute to this risk.
A U.S. government report on marijuana research also looked at the gateway theory. It stated that marijuana use is linked with misusing other substances. But most people using marijuana don’t go on to use harder drugs.
If you use marijuana, will you eventually get desensitized to the high and crave something stronger?
Researchers sometimes study rodents because they have many genetic and behavior variations, much like humans. Animal studies can provide direction and critical data for human studies on addiction.
We don’t have human data about the neural mechanisms involved with addiction. But animal studies can provide some insight. One rodent study showed that using marijuana at an early age can dull the brain’s reward center. This tolerance increases their chance of developing other addictions. Another animal study explains how using one substance can become cross-sensitized to others. These and other animal studies reveal important clues about substance use. But we don’t know if these outcomes are true for humans.
This connection lends support to the gateway theory for marijuana use. But more research data is needed to make any conclusions. We know that alcohol and tobacco can have a similar effect. So it may be true that genetic and social environments may create more risk than the substance itself.
Real risks of marijuana use
The teenage brain is sensitive to the effects of marijuana. Heavy use at a young age can harm brain development.
Here are some of the negative outcomes teens may experience with heavy marijuana use:
Lower IQ scores and grades in school
More prone to depressed mood, anxiety, and irritability in young adulthood
Lower resiliency in young adulthood
Risk developing an addiction more quickly than adults
Marijuana use does not automatically lead to harder drugs. But research studies have revealed links between marijuana and opioid substances. A person’s environment and genetic background can lead to these problems:
The relationship between medical marijuana and opioids is complex and may not be causal. But people using medical marijuana are more likely to report using opioids for medical and non-medical reasons.
People with an addiction to marijuana were 3 times more likely to develop a heroin addiction.
What factors contribute to progressing from marijuana to harder drugs?
The common liability theory of addiction explains that risk factors for drug use are common among many substances. The risk for misusing substances doesn’t necessarily develop in a straight line. Instead, these common factors increase risk in several ways. We’ll review the most significant ones below.
Mental health issues
People often use substances to manage their emotions. This means adults and teens with mental health issues are more likely to use substances. For people using marijuana, mental health issues can also increase their risk of progressing to harder drugs.
Genetics
Genetic factors can increase a person’s odds of misusing substances. One study found connections related to family history. The greatest risk came from families with high-risk behaviors, schizophrenia, and introversion. Between 50% and 70% of this risk may stem from a person’s genetic background.
Social context and available substances
One study stated that the gateway to substance use was linked to time and place. It’s more like a chain of opportunities than a specific link between drugs. A person’s social environment presents opportunities to use or avoid substances. Whatever substance is easiest to get becomes a gateway to substance misuse.
Does legalizing marijuana lead to experimentation with other drugs?
For preteens and teens, there’s no clear answer about marijuana and harder drugs. A national report showed that marijuana use has increased for younger teens since 2019. But an annual survey from the University of Michigan shows little overall change in teen marijuana use.
The effect on adult use is also hard to define. Marijuana use has been common among adults for years before it was legal. Also, some states with legalized medicinal and recreational marijuana were among those with the smallest increase in overdose deaths from 2013 to 2017. Does this mean that adults were more likely to use legalized marijuana than harder drugs? It’s possible, but the picture is still unclear.
Marijuana usage can progress, but it’s not proven as a gateway drug
Connections do exist between marijuana use and later use of harder drugs. But many research studies over the last several years have revealed a different picture. Connections and causation aren’t the same. Marijuana does not lead to harder drugs for most people who use it.
Progression to harder drugs is significant when other risk factors are present. Genetics, behavioral family history, and environment have a large impact. These common factors can make the difference between experimentation and addiction.
The bottom line
The gateway theory is a well-known explanation for substance use risk. But addiction is complex, and many problems can’t be traced to a clear starting point. The gateway theory is easy to understand, but it gives an inaccurate picture. When it comes to using harder drugs, a person’s life situation may matter more than the substances themselves.
If you or someone you know struggles with substance use, help is available. Call SAMHSA’s National Helpline at 1-800-662-HELP (4357) to learn about resources in your area.
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