Gateway Drugs: How Does Addiction Start?

It’s no secret that a substance abuse addiction can be utterly ruinous. A drug habit or a dangerous drinking problem can end careers, relationships, families and lives, leaving misery and heartbreak in its wake. For all the anguish and destruction caused by an addiction, the genesis can be so innocuous: a small shot here, a little smoke there. The questions of gateway drugs and how addiction starts are still debated by scientists, doctors and psychologists, but the truth remains: the seismic effects of a substance abuse problem can be born from the smallest of cracks.

How Does Addiction Actually Start?

start of addiction

The hooks of addiction take root so easily because, to put it bluntly, we are motivated by pleasure. While pleasure manifests differently for everyone – watching sports, having sex, listening to certain forms of music, going on a roller coaster – the way the human brain processes these pleasurable sensations is universal.

Whenever we do something we enjoy doing, our brain releases a chemical called dopamine. This process serves an evolutionary role: it’s how we learn that some things are enjoyable, and some things are not. When we do something that makes us feel good, our brain releases dopamine to teach us to seek out this activity in the future. If we enjoy having sex once, we look forward to having sex again because we remember that the activity was pleasurable – and that memory was formed from the brain releasing dopamine.

In a healthy brain, dopamine is eventually reabsorbed. No matter how enjoyable the activity, we find ourselves wanting to move on – to take a break. The brain files the association away for future reference, and dopamine levels return to normal. We go on with life.

However, when a person takes drugs – illegal, prescription or recreational – the chemical functioning of the brain is changed. One of those changes is that the brain is made to produce more dopamine than it would for a non-drug-related stimulus, and reabsorption of the dopamine is blocked, prolonging the sense of pleasure beyond a natural limit. [1] The sensations are so much more powerful and long-lasting than what arise from healthy sources of enjoyment that a person is compelled to seek out another hit or another drug. In time, things like exercise, concerts and sex don’t do it anymore, and the only way the user can experience any form of pleasure is from taking drugs or alcohol. Eventually, the body and mind become so hooked on the drugs that to not take them causes agonizing and excruciating withdrawal symptoms, sealing the downward spiral of addiction.

Risk Factors (Nature vs. Nurture)

While hard drugs (like cocaine, heroin, and methamphetamines) are infamous for how potently they can twist a brain, milder substances – such as alcohol, marijuana, and certain forms of prescription medication – are not as powerful, and thus not thought of as posing similar risks. On their own, they may not, but when they are combined with certain risk factors, they may influence (or even predict) whether a marijuana smoker, a recreational drinker, or a prescription drug patient starts abusing their substances or moves on to more dangerous substances.

Hence, these relatively lighter substances are claimed to play the role of the gateway, introducing a user to a world of addiction, dependence, and/or purely harmful drugs. The extent to which they play their respective roles is still a matter of debate, and one of the components of that debate is the role of the risk factors mentioned above. The Mayo Clinic compiled a list of what such factors might look like:

  • Family history of addiction
  • Stressful home environment
  • Pressures at work or school
  • Having a mental health condition (such as anxiety or depression)
  • Peer pressure (to smoke or drink)
  • Lack of education about the nature of the substances they are taking
  • Access to more of the substances or other drugs[2]

For example, a study published in the American Journal of Psychology concluded that use of marijuana in adolescents was subject to the “proneness to deviancy and drug availability in the neighborhood.”[3] The Journal of the American Medical Association reported on a study conducted on 311 pairs of twins in Australia; one twin used marijuana by age 17, and the other twin did not. Those who used marijuana were four times more likely than their abstaining twin to use psychedelics, three times more likely to use cocaine, and two times more likely to use opioids.

The authors of the study speculated that the link between early marijuana use and harder drug use later in life may come from “the effects of peer and social context,” and pointed out that using cannabis at an early age may “reduce perceived barriers” to other illegal drugs.

Commenting on the study, Reason magazine argued that the study does not mention a “specific pharmacological effect” between smoking marijuana and later moving on to more dangerous substances.[4] A marijuana user – perhaps with opportunities and temptations to engage in risky behavior – “may be more inclined” to experiment with other substances, says Reason.

But it’s not just the environment that plays a role in influencing whether or not a person who starts smoking pot or drinking alcohol becomes an addict. Genetics, for example, can increase the risk of someone becoming an alcoholic (the gene responsible for the production of dopamine might magnify the pleasurable effects of alcohol, thus making a person more likely to keep drinking beyond safe levels), or even diminish the risk of someone becoming an alcoholic (members of a certain ethnic group have a genetic mutation that makes classic hangover symptoms occur almost immediately, dissuading them from continuing to drink).

This point is stressed by a blog on Psychology Today, which posits that individuals with a “reduced ability to control impulses” are more likely to put themselves in situations that threaten their well-being.[5] The writer summarizes by saying that the issue of addiction is, on some level, physical and neurochemical.

A different article on Psychology Today follows suit: “the genetic component,” says that writer, “is a huge component in what creates the addict or the alcoholic.”[6]

A blog on Psych Central sums it up best: “most people who become addicts are subject to a combination of risk factors.”[7] Anything from childhood trauma and having alcoholic parents to being exposed to drugs at an early age or various permutations thereof can influence whether a person takes their first hit or their first drink, and whether that same person goes on to develop a problem.

The Wide Gate

Cannabis – or, when taken recreationally, better known as marijuana – is consistently at the center of the “gateway drug” debate. It is one of the most popular drugs in the world today, reaching 22.7 percent of 17 to 18 year olds in 2013.[8]


There has long been fear that the relative ease of procuring marijuana compared to other drugs, as well as the milder effects of marijuana, might entice users to experiment with more illicit substances when the novelty of marijuana wears off (or when their inhibitions are sufficiently reduced, since one of the effects of marijuana is that of lowered inhibitions).

A study published in the journal Neuropsychopharmacology said that, with marijuana, there is an “insidious” chance of developing a dependence on the drug as opposed to merely abusing it.[9] That particular quality of marijuana is derived from its apparent harmlessness. With cocaine, for example, the high can be instantaneous and overpowering, which serves as a warning sign for users; with marijuana, the effect is much weaker, and there is a small chance of developing an addiction with one hit. This is what leads many smokers to feel that they can continue to use marijuana, since their first hits did not cause significant alarm or drastic changes in behavior.

With inhibitions lowered by marijuana, there is the temptation to experiment with other drugs. Indeed, a study published in the journal Addiction found that participants who smoked cannabis more than 50 times a year had “hazards of other illicit drug use” that were 140 times higher than people who did not use marijuana.[10]

However, the authors of the study stopped short of definitively claiming that cannabis was a gateway drug; instead, they concluded that cannabis “may” act as a gateway drug, and that the association between marijuana and harder drug use is “non-causal.”

‘Correlation Isn’t Cause’

That point is strongly echoed in an article published by TIME, the title of which makes this school of thought clear: “The Myth That Will Not Die.”[11] The article quotes the National Institute on Drug Abuse as saying a person who smokes marijuana is 104 times more likely to use cocaine, but, citing other research, criticizes the assumption that marijuana leads to more dangerous forms of drug abuse. “The problem,” explains the TIME writer, “is that correlation isn’t cause.”

A 1999 report by the Institute of Medicine went so far as to say that “there is no conclusive evidence that the drug effects of marijuana are causally linked to the subsequent abuse of other illicit drugs.” The report instead pointed out that “underage smoking and alcohol use” are bigger “gateways” to more destructive behavior, since they typically precede marijuana use (possibly by virtue of cigarettes and alcohol being easier to obtain than marijuana at the time of the study’s publication).[12]

In 2002, the Parliament of Canada’s Senate Special Committee on Illegal Drugs reported that the gateway theory, with regard to cannabis, “has not been validated by empirical research,” and that cannabis on its own does not cause users to seek out other drugs.[13]


The Other Gateways: Nicotine and Alcohol

alcohol and cigarettes

There is further evidence to support the claims that marijuana does not have a monopoly on the “gateway hypothesis.” Another study published in the journal Addiction noted that “tobacco use often precedes the onset of cannabis use,” further mentioning “shared genetic liability” and environmental influences such as cultural norms as reasons that tobacco users might move on to marijuana.[14]

In “Why Nicotine is a Gateway Drug,” the National Institute of Health explains that studies conducted on mice showed that “nicotine […] makes the brain more susceptible to cocaine addiction.”[15] While there was long believed to be a behavioral connection between using nicotine and going on to use cocaine (as an example of harder drugs), the NIH explains that researchers “identified a biological mechanism” which they hope will allow them to explore how the “molecular mechanisms” of alcohol and marijuana act as gateway drugs.

Researchers writing for the Journal of School Health concluded in their study that alcohol was most deserving of the “gateway” label; from data provided by the University of Michigan’s Monitoring the Future program, they found that alcohol led to the use of tobacco, marijuana, and other controlled substances, and students who used alcohol showed a “significantly greater likelihood” of abusing drugs.[16]

In 2007, a study published in the Journal of Adolescent Health also pointed to an association between tobacco and alcohol and the abuse of prescription medication (previous alcohol, cigarette, and marijuana use each has their own rates of associations with current abuse of prescription opioids).[17]

Prescription medications themselves can also be considered “gateway drugs.” Researchers at the University of Buffalo found that 31 out of 75 patients hospitalized for opioid detoxification “first became addicted to legally prescribed painkillers.”[18] Prescription medications are easy to obtain, and sometimes taken without consideration for side effects and appropriate dosages. Their effects – sedating, stimulating, pain-relieving, etc. – can mimic the effects of narcotics and other controlled substances, and if a patient meets enough risk factors, there is a feasible possibility that the misuse of prescription medication can lead to experimentation with more dangerous substances.

Drug Abuse vs. Drug Dependence

While the terms “drug abuse” and “drug dependence” are sometimes used interchangeably,[19] they are two different yet connected stages of a substance addiction. Broadly speaking, abuse covers the behavioral and social effects of a drug problem, while dependence deals more with psychological and physical factors.

For example, the term “drug abuse” is best used to describe:

  • Decline in academic or professional performance as a result of the drug habit
  • Engaging in risky behavior (drunk driving, promiscuous sexual behavior, etc.)
  • Persisting with the drug habit, despite direct consequences

Such signs are undeniable indicators of a drug or alcohol problem that requires immediate attention, but they are not what are medically accepted to be signs of “drug dependence.” Dependence is a state where the user has been taking drugs or alcohol for so long that they have reached the point where they cannot function without more intake. For example, not drinking – either because there is no alcohol on hand, or as a result of an attempt to get clean – causes painful and stressful withdrawal symptoms, making the drinker desperate for more alcohol to relieve the distress.

Another sign of drug dependence is that the user’s tolerance levels increase with the more drugs they take. They need larger amounts of the substance in order to feel the same effect. While the sensations of the drug remain the same, the chemical dependency being inflicted upon the brain grows and grows, to the point where the user has to take their poison to simply make it through the day. Anything less, and the withdrawal symptoms mentioned above may kick in.

drug abuse vs dependence

The line between abusing drugs and becoming dependent on them is not a straight one, says the National Institute on Drug Abuse.[20] Physical dependence on a drug does not always constitute an addiction, but the two often go hand in hand.

Overall, drug abuse is a spectrum, starting from experimentation and ending in a full-blown addiction. Young people often move through the spectrum more quickly than older people do.[21] Researchers at the National Center on Addiction and Substance Abuse also point to adolescence as the key period in a person’s life when they are most in danger of growing the seeds of an addiction.[22] As you’ve read above, this could be due to the strong influence of peers and environment during that stage of development; it can also be because teenage brains “[work] differently,” according to a researcher at the University of Pennsylvania, who told Livescience that teenagers perceive situations and react to them differently.[23] It is this difference that puts teenagers at risk for taking risks, and one of those risks might be to experiment with a gateway drug.

Addiction is complicated, and the question of gateway drugs cannot be answered easily. But what’s simple is that no matter what questions you have, no matter how worried you might be for yourself or a loved one, there are always answers. Treatment is one of those answers.


[1]Understanding Addiction.” (n.d.) Accessed November 28th, 2014.

[2]Drug Addiction Risk Factors.” (October 2014). Mayo Clinic. Accessed November 28, 2014.

[3]Predictors of Marijuana Use in Adolescents Before and After Illicit Drug Use; Examination of the Gateway Hypothesis.” (December 2006). American Journal of Psychiatry. Accessed November 28th, 2014.

[4]High Road.” (January 2003). Reason. Accessed November 29th, 2014.

[5]How Does It All Start? My Thoughts on Addiction Causes, Sex Addiction and Substance Abuse.” (February 2010). Psychology Today. Accessed November 29th, 2014.

[6]Nature vs. Nurture.” (May 2014). Psychology Today. Accessed November 29th, 2014.

[7]Addiction: Nature versus Nurture.” (March 2014). Psych Central. Accessed November 29th, 2014.

[8]DrugFacts: High School and Youth Trends.” (January 2014). National Institute on Drug Abuse. Accessed November 28th, 2014.

[9]From First Drug Use To Drug Dependence; Developmental Periods of Risk for Dependence Upon Marijuana, Cocaine and Alcohol.” (April 2002). Neuropsychopharmacology. Accessed November 28th, 2014.

[10]Does Cannabis Usage Encourage Other Forms of Illicit Drug Use?” (April 2000). Addiction. Accessed November 28th, 2014.

[11]Marijuana as a Gateway Drug: The Myth That Will Not Die” (October 2010). TIME. Accessed November 28th, 2014.

[12]Marijuana and Medicine: Assessing the Science Base.” (1999). National Academy of Sciences. Accessed on November 28th, 2014.

[13]Cannabis: Our Position for a Canadian Public Policy.” (September 2002). Senate Special Committee on Illegal Drugs. Accessed November 29th, 2014.

[14]Clinical Correlates of Co-Occurring Cannabis and Tobacco Use: A Systematic Review.” (August 2012). Addiction. Accessed November 28th, 2014.

[15]Why Nicotine is a Gateway Drug.” (November 2011). NIH Research Matters. Accessed November 28th, 2014.

[16]Alcohol as a Gateway Drug: A Study of U.S. 12th Graders.” (June 2012). Journal of School Health. Accessed November 28th, 2014.

[17]Previous Use of Alcohol, Cigarettes and Marijuana and Subsequent Abuse of Prescription Opioids in Young Adults.” (April 2007). Journal of Adolescent Health. Accessed on November 28th, 2014.

[18]Prescription Painkillers Could Be New “Gateway” Drugs.” (August 2010). US News & World Report. Accessed November 29th, 2014.

[19]Abuse vs. Dependence.” (n.d.) HBO. Accessed November 29th, 2014.

[20]Is There a Difference Between Physical Addiction and Dependence?” (December 2012). National Institute on Drug Abuse. Accessed November 29th, 2014.

[21]Substance Use Disorder.” (February 2014). MedlinePlus. Accessed November 29th, 2014.

[22]Addiction Starts Early in American Society, Report Finds.” (June 2011). US News & World Report. Accessed November 29th, 2014.

[23]Why Teens Are More Prone to Addiction, Mental Illness.” (January 2012). Livescience. Accessed November 29th, 2014.

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