Understanding Gateway Drug Theory & Gateway Drugs

Gateway drug theory is a medical hypothesis or, in lay terms, a hunch based on studied trends around first-time drug use. The theory posits that the use of one habit-forming drug opens the door to other drugs of abuse, thus increasing the probability of addiction to these other potentially more dangerous and illicit drugs. Gateway drugs are therefore usually legal, habit-forming drugs that, if not the source of an existing addiction, can lead to one or more addictions. This article will educate readers on gateway drug theory, how it came to be, and why, according to studies, alcohol, nicotine and marijuana are the leading gateway drugs.

Gateway Drugs and Teen Substance Abuse: How the Theory Developed

What are gateway drugs and how did the gateway theory develop? The development of the gateway drug hypothesis can be traced back to the 1970s. (The term itself was coined in the 1980s.) That is when the first of many studies into adolescent drug abuse and its beginnings revealed a common trend: that drug abuse seemed to develop sequentially and in stages, often starting with beer or wine.

Most teens surveyed in national drug use and behavior studies had some experience with alcohol and/or cigarettes, but did not go on to experiment with other drugs. However, a majority of those who went on to become heavy drug users reported first drinking or smoking before using cocaine or heroin. Additionally, the progression of their drug use tended to go from alcohol and/or tobacco (nicotine) to marijuana, and then from marijuana and alcohol to illicit drugs such as cocaine or heroin, according to a University of Cambridge article that summarized the results of these first studies. The same article went on to imply that this sequential pattern of drug use still largely describes today’s heavy drug users.

Strikingly, the researcher who reportedly coined the term “gateway drug” was a woman by the name of Denise Kandel, whose primary research interest has been not alcohol or marijuana but nicotine. In a recent segment on National Public Radio, Dr. Kandel shared her findings, published in the New England Journal of Medicine, that show the molecular basis for nicotine being a gateway drug. The implication? That of the three main gateway drugs, nicotine may actually be the most potent.

The Link Between Gateway Drugs and Addiction

The link between gateway drugs and addiction—and how to account for it—remains a source of ongoing debate within the scientific research community. To what degree a gateway drug “causes” later experimentation with illicit drugs remains unclear. Some speculate, for example, that alcohol use alters the brain, making the brain biologically susceptible to the allure of other drugs. Alcohol is “the real gateway drug,” an article in The Washington Post declared.

Others are hesitant to interpret the link between gateway drugs and addiction as causal. In their view, the data on drug use initiation and sequencing is too variable to establish a causal link between alcohol use and later drug abuse and addiction. Instead, these researchers propose that drug abuse and its progression have more to do with the shared attitudes and pathologies of those who abuse drugs, as opposed to the biological effects of a gateway drug. “Common liability” is the name they assign to their theory, and recent research has explored these potential areas of liability, or vulnerabilities to substance use disorders. (A more obvious one among drug users is the high frequency of co-occurring disorders like depression and/or post-traumatic stress disorder, for example.)

The Big Gateway Drugs: Alcohol, Nicotine and Marijuana

Some examples of gateway drugs include alcohol, nicotine, and marijuana. A whole body of literature has since accumulated regarding alcohol, nicotine and marijuana, and their manifestation as precursors to heavier drug use. What follow are key findings from these studies as they pertain to alcohol, nicotine and marijuana (in that order):

Alcohol has been dubbed the “leading gateway drug,” based on a long history of scrutiny. More recently, researchers at Texas A&M and the University of Florida set out to establish which substance teens typically used first. Their study examined data from 2,800 U.S. 12th graders surveyed as part of the “Monitoring the Future” study, an annual federal survey of teen drug use. Alcohol clocked in as the most widely used substance, according to the findings, with 72 percent of teens reporting they had used alcohol at some point in their lives. Strikingly, the study also revealed that high school seniors who used alcohol were significantly more likely—up to 16 times more likely—to use other licit and illicit substances. The researchers also found that the social acceptability of alcohol, like that of cigarettes, was a contributing factor here. In summation, alcohol was the substance teens used earliest—and the earlier a teen’s drug use, the higher their risks of a later substance abuse problem—as well as the most commonly used drug. (The study appeared in the Journal of School Health.)

Nicotine is another drug that can act as a gateway to illicit drugs, based on the fact that in a recent national survey, over 90 percent of adult cocaine users between the ages of 18 and 34 had smoked cigarettes before using cocaine. In a study in 2011, researchers asked why this was so. They found (in research with mice) that nicotine exposure makes the brain more susceptible to cocaine addiction. Such findings also make the growing popularity of e-cigarettes among teens in this country a source of concern and the focus of yet more research.

Marijuana is also a key gateway drug. Pot’s recent legalization in various states for medical and recreational purposes has meant that marijuana use is now increasingly more socially acceptable. To what degree the drug will eventually surpass alcohol as the leading gateway drug thus remains to be seen. However, what is already clear from the research is that a great majority of illicit drug users tried marijuana first.

Gateway Drugs and Prescription Drug Abuse

Alcohol, nicotine and marijuana use also seem to precede prescription drug abuse. According to a study at Yale University, use of these gateway drugs appears to predict greater risk of abusing opioids. The Yale researchers found young adults who smoke cigarettes or use alcohol or marijuana are two to three times more likely to go on to abuse prescription painkillers.