Gateway Drugs: Fact or Fiction?

Research, reviews and animal studies indicate that the gateway drug theory may be somewhat accurate. The use of certain drugs may lead to the use of others.

I think, at some point, we have all heard the term “gateway drug.” This is a phrase common to substance abuse education programs. This term is based on a theory that suggests that the use of a particular substance increases the risk of the abuse of other substances in the future. As such, the first substance acts as a “gateway” into the world of drug abuse. While this theory has been hotly debated, there is most certainly significant evidence to support this claim. 

However, the most important thing to remember with any type of research is that the objective is always to find correlation, not causation. One cannot say, completely and unequivocally, whether the use of a particular substance leads to the abuse of or addiction to another, but there are statistics and metrics that demonstrate a link between the two. Whether or not you believe in the gateway theory, it is important to understand the risks associated with the use of “less harmful” substances and to make healthy and responsible choices given that information.

What Are Gateway Drugs?

So, what qualifies as a gateway drug? As previously mentioned, a gateway drug is typically perceived as less harmful or “addictive” than substances like cocaine, meth and heroin. Specifically speaking, the term gateway drug refers to marijuana, alcohol and tobacco. It is crucial to understand, however, that just because they are “gateways” does not mean they are inherently safe or “harmless.” In fact, the Centers for Disease Control and Prevention states that “smoking is the leading cause of preventable death.” Furthermore, several studies suggest that the use of tobacco early on in life often leads to the development of other dependencies in the future. One of these studies involved giving nicotine to rats early on in their development. This study found that the rats that had been given nicotine responded more dramatically to cocaine later on. 

In terms of alcohol, the National Institute on Alcohol Abuse and Alcoholism reported that those between the ages of 18 and 24 have an increased likelihood of a concurrent alcohol use disorder and other drug misuse than those older than them. Studies have also shown that students who reported that they used alcohol in the sixth grade had higher rates of “illicit substance use” than those who reported their first exposure to alcohol being in the ninth grade. However, the drug most commonly associated with being a gateway drug is marijuana. 

Animal studies have suggested that young rodents that are given THC show a greater potential of developing addictions to other drugs. This early THC also significantly alters neurological pathways in rats and mice, some of which could increase susceptibility to addiction. Another study examined thousands of people who indicated that marijuana was the first drug that they used. The research demonstrated that there was a 44.7% chance that these people would use other drugs. This probability is much greater than that of the general population.

How Drugs Act as Gateways

There are two overall ideas behind the gateway drug theory, and these theories have to do with brain structure and genetic makeup. The first idea is that a gateway drug fundamentally changes pathways in the brain. There are a lot of animal studies that tend to back up this theory. As a future speech language pathologist, a decent amount of my studies have focused on how malleable the brain itself is. Our brains are constantly evolving and changing. There are specific things that make brains change more than others. Substances like drugs and alcohol are some of those things. 

When you think about it, it makes sense that exposure to certain substances could lead to changes, particularly within the parts of the brain that drug use activates. Post-mortem brain studies of rodents exposed to substances like nicotine showed increased volume of the reward system compared to animals not exposed to addictive substances. Of course, there are very obvious differences in the brain structures of animals like rodents and humans. Regardless, the brains of humans are still extremely moldable and ever-changing. That is a fact that should never be overlooked. 

Another aspect of this theory centers upon genetic makeup. Much of the information we have about the interaction of genes and the environment in regard to substance abuse comes from twin studies. These studies allow, on a more dramatic level, the exploration of how much control one’s genes have over certain aspects of their lives. What has been found points to a strong genetic influence on drug abuse, and that is seen in those who use more than one substance. Thus, certain people may have differently structured neural pathways that make them more susceptible to substance abuse disorders.

“Safe” Doesn’t Mean Safe

Again, we cannot infer causality. Despite the rules that govern how we are to view results from studies, the evidence cannot and should not be ignored: There is some connection between the use of certain drugs and the implication of future drug use. No one plans to or wants to have a disease; thus, no one plans to or wants to struggle with dependence on a substance. But the fact that 10% of Americans will struggle with an addiction demonstrates the fact that there is significant danger in experimentation with substances. 

While drugs like tobacco, alcohol and marijuana may seem culturally benign, they present a very real threat. Just because a substance does not have a reputation for being “highly addictive” like cocaine or heroin does not mean that it is entirely safe. In fact, it could mean that it is even more dangerous because it seems less harmful. Also, the use of a less harmful drug could lead to a false sense of security about one’s ability to handle illicit substances. In reality, it is always best to have a healthy respect for substances. There is no way of knowing how your body will respond to using any type of drug.


Centers for Disease Control and Prevention. “Fast Facts.” May 21, 2020. Accessed October 1, 2020.

Levine, Amir; et al. “Molecular Mechanism for a Gateway Drug: […]pression by Cocaine.” Science Translational Medicine, November 2, 2011. Accessed October 1, 2020.

National Institute on Alcohol Abuse and Alcoholism. “Alcohol and Other Drugs.” July 2008. Accessed October 1, 2020.

Barry, Adam; et al. “Prioritizing Alcohol Prevention: Establi[…]th Illicit Drug Use.” The Journal of School Health, January 2016. Accessed October 1, 2020.

Zehra, Amna; et al. “Cannabis Addiction and the Brain: a Review.” Journal of Neuroimmune Pharmacology, 2018. Accessed October 1, 2020.

Secades-Villa, Roberto; et al. “Probability and predictors of the cannab[…]t: a national study.” The International Journal on Drug Policy, February 2015. Accessed October 1, 2020.

Zickler, Patrick. “Twin Studies Help Define the Role of Gen[…]ility to Drug Abuse.” National Institute on Drug Abuse Archives, November 1, 1999. Accessed October 1, 2020.

National Institutes of Health. “10 percent of US adults have drug use di[…]oint in their lives.” November 18, 2015. Accessed October 1, 2020.

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