The term “gateway drug” is used as a keyword when the consumption of a substance is more likely to lead to the consumption of other (sometimes harder) drugs.
The theory of the gateway drug is based on observations that the sequence of the first consumption of drugs and the consumption of other drugs does not occur randomly but follows a particular course. In discussions, cannabis is often at the center, it lays the foundation for the later consumption of harder drugs, they argue. Still, many authors regard ethanol, i.e., alcohol, nicotine, and caffeine, as gateway drugs.
- 1 History and origin of the term
- 2 Connections
- 3 Health policy implications
- 4 Behavioral addictions
- 5 Criticism of the gateway drug theory
- 6 Gateway drug theory studies
- 7 Weblinks
- 8 References
History and origin of the term
Since 1975, several longitudinal studies have been conducted on the chronological order of the first use of drugs. Among other things, the study “Stages in adolescent involvement in drug use” was published. Professor Denise Kandel, director of the Substance Abuse Epidemiology Division at the New York State Psychiatric Institute, and other colleagues with this and similar research provoked intense political and scientific discussions about the possibility of the causes. Terms such as stepping-stone theory, gateway theory, or gateway drug have thus become established.
Exploring the actual underlying cause for the chronological sequence of the consumption of other drugs (after the first consumption) is very difficult. It allows most conjectures, so two main theories about possible connections have emerged.
Certain studies are based on the theory that the cause (for the chronological sequence of the consumption of other drugs) lies in the imprinting of the brain – by the consumption of an earlier substance. Another approach explains the chronological sequence through personal and social factors.
The concept of biological imprinting assumes that the first use of a drug causes imprinting in the brain and is, thus, the cause of the consumption of other drugs.
In various animal experiments, they tested whether the use of a drug increases the attractiveness of using other drugs. Using mice as experimental animals, one found that nicotine increases later consumption of cocaine. In this experiment, one could determine an underlying molecular-biological change in the brain. Therefore, one assumes that nicotine consumption links to an increased probability of cannabis and cocaine consumption.
The second theory holds that the order in which different drugs are used is based on personal and environmental factors – cross-drug motivation (common liability). Social and economic conditions play a major role in this concept. This theory has now been supported by an extensive genetic analysis examining a genetic link between cannabis use and cigarette smoking.
However, a study with twins concluded that genetic and environmental influences only play a small role or possibly only in some consumption sequences. They tested two hundred nineteen pairs of Dutch twins: one had used cannabis before 18, but the other had not. Those who had used cannabis before 18 were seven times more likely to use later “party drugs”; the later use of “hard drugs” was increased by 16 compared to the latter. Based on the study results, the researchers assume that the various sequences cannot be explained, at least by genetic or social influences.
Health policy implications
The first theory describes the imprinting of the brain by a previously used drug so that one would attach great importance to the causal effect of this drug. In this case, a targeted approach to the drug to limit the risk is a suggestion. For example, restrict access – especially for people of an early age.
If one proceeds from the last-mentioned theory, that is, the motivation of the consumer across all drugs as the main reason for the subsequent use of other drugs, the following measures to limit risk were introduced as a proposal by the International journal on drug policy: Rather, the initial situation of people (and information and personal development support) at the center of political discussion as the properties of individual drugs are moved.
Some authors extend the gateway drug hypothesis to behavioral addictions, particularly media use. They assume a connection in the consumption of media that is viewed as problematic – for example, one finds pornography or first-person shooters in discussions repeatedly.
Pornography critics claim that consuming “normal” porn films must also be seen as a kind of gateway drug and would lead to ever harder porn films. To do justice to the ever-increasing experience, the consumers would ultimately end up as sex criminals. The PorNO campaign called for stricter restrictions on pornography. Although a wide distribution of pornographic films via the Internet is predominant, one observed a constancy or a decrease in sexual offenses simultaneously.
Killer games/horror movies
Some authors assume that horror films and video games with scenes of violence increase the tendency toward violence and would ultimately lead to an increase in crime.
Criticism of the gateway drug theory
A common criticism of the gateway drug theory is that it almost exclusively involves a past view of people with a devastating drug history. There is proof that most drug addicts, such as cocaine and heroin, have used cannabis earlier; Conversely, only very few cannabis users have had experience with these “hard” drugs. In addition to cannabis, the same applies to ethanol (i.e., alcohol), nicotine, and caffeine; before using cannabis for the first time, consumers usually come into contact with these legal drugs.
Gateway drug theory studies
In the study “Probability and predictors of the cannabis gateway effect,” a sample of 6624 people was collected who had not used any other illegal drugs before using cannabis. They estimated the probability of subsequent use of other illicit drugs at 44.7%. Personal and social factors such as origin, urbanity, education status, age, and gender influenced the probability level.
The investigation “Alcohol as a gateway drug: a study of US 12th graders” in America of approx. 14,500 students in the 12th grade concluded that there is a high probability of a connection between alcohol consumption and later use of tobacco, cannabis, and other illegal substances.
A US study (Is cannabis use associated with an increased risk of onset and persistence of alcohol use disorders?) also showed, based on 27,461 people, that those who had no alcohol problems before consuming cannabis were five times more likely to develop alcohol problems after three years than those who had not used cannabis.
Is cannabis a gateway drug?
However, the theory cannabis is a gateway drug has been disproved by numerous studies. About 2 to 5 percent of cannabis users switch to hard drugs later; this does not apply to 95 to 98 percent of these consumers.
As early as 1998, the study commissioned by the then Federal Health Minister Seehofer (CSU) concluded: “The assumption that cannabis is the typical gateway drug for the use of hard drugs such as heroin is therefore not tenable based on current scientific knowledge.”
After examining scientific literature, the Federal Constitutional Court in 1994 described the thesis cannabis as a gateway drug as “predominantly rejected.”
An American report by the “Institute of Medicine” also concluded that cannabis is not a gateway drug. For every approximately 80 million cannabis users, there are several hundred thousand hard drug users, a ratio of 100 to 1.
In summary, one can state that research on cannabis as a possible gateway drug speaks for itself: Complex causes and processes are the characteristics of the path to drug consumption. The vast majority of studies assume that cannabis is just one factor among many different ones and, according to current results, cannot be considered a gateway drug.
 D. Kandel: Stages in adolescent involvement in drug use. In: Science. Band 190, Nummer 4217, November 1975, S. 912–914.
 K. Yamaguchi, D. B. Kandel: Patterns of drug use from adolescence to young adulthood: II. Sequences of progression.In: American journal of public health. Band 74, Nummer 7, Juli 1984, S. 668–672.
 D. Kandel, K. Yamaguchi: From beer to crack: developmental patterns of drug involvement. In: American journal of public health. Band 83, Nummer 6, Juni 1993, S. 851–855.
 A. R. Morral, D. F. McCaffrey, S. M. Paddock: Reassessing the marijuana gateway effect. In: Addiction. Band 97, Nummer 12, Dezember 2002, S. 1493–1504.
 D. M. Fergusson, J. M. Boden, L. J. Horwood: Cannabis use and other illicit drug use: testing the cannabis gateway hypothesis. In: Addiction. Band 101, Nummer 4, April 2006, S. 556–569
 M. Yuan, S. J. Cross, S. E. Loughlin, F. M. Leslie: Nicotine and the adolescent brain. In: The Journal of physiology. Band 593, Nummer 16, August 2015, S. 3397–3412.
 K. M. Keyes, A. Hamilton, D. B. Kandel: Birth Cohorts Analysis of Adolescent Cigarette Smoking and Subsequent Marijuana and Cocaine Use. In: American journal of public health. [elektronische Veröffentlichung vor dem Druck] April 2016.
 S. Galea, R. Vaughan: A Public Health of Consequence: Review of the June 2016 Issue of AJPH. In: American journal of public health. Band 106, Nummer 6, Juni 2016, S. 973–974.
 M. M. Vanyukov, R. E. Tarter, L. Kirisci, G. P. Kirillova, B. S. Maher, D. B. Clark: Liability to substance use disorders: 1. Common mechanisms and manifestations. In: Neuroscience and biobehavioral reviews. Band 27, Nummer 6, Oktober 2003, S. 507–515.
 L. Degenhardt, L. Dierker u. a.: Evaluating the drug use “gateway” theory using cross-national data: consistency and associations of the order of initiation of drug use among participants in the WHO World Mental Health Surveys. In: Drug and alcohol dependence. Band 108, Nummer 1–2, April 2010, S. 84–97.
 S. Stringer, C. C. Minică u. a.: Genome-wide association study of lifetime cannabis use based on a large meta-analytic sample of 32 330 subjects from the International Cannabis Consortium. In: Translational psychiatry. Band 6, 2016, S. e769.
 M. T. Lynskey, J. M. Vink, D. I. Boomsma: Early onset cannabis use and progression to other drug use in a sample of Dutch twins. In: Behavior genetics. Band 36, Nummer 2, März 2006, S. 195–200.
 Wayne Hall, Rosalie Liccardo Pacula: Cannabis Use and Dependence. Public Health and Public Policy. Cambridge University Press, Cambridge, UK, New York, USA, 2003, ISBN 978-0-521-80024-2, S. 111.
 R. Secades-Villa, O. Garcia-Rodríguez, C. J. Jin, S. Wang, C. Blanco: Probability and predictors of the cannabis gateway effect: a national study. In: The International journal on drug policy. Band 26, Nummer 2, Februar 2015, S. 135–142.
 Kirby, A. E. Barry: Alcohol as a gateway drug: a study of US 12th graders. In: The Journal of school health. Band 82, Nummer 8, August 2012, S. 371–379.
 A. H. Weinberger, J. Platt, R. D. Goodwin: Is cannabis use associated with an increased risk of onset and persistence of alcohol use disorders? A three-year prospective study among adults in the United States. In: Drug and alcohol dependence. Band 161, April 2016, S. 363–367.