Drug War Distortions: Gateway Theory

Distortion 7: Marijuana is a gateway drug that leads to heroin and cocaine addiction.
False. The ‘gateway’ claim is a myth. Marijuana is the most widely used illicit drug so it is very likely that people who use less commonly-used drugs will have also tried marijuana. That does not mean marijuana led to hard drug use. The research indicates most marijuana users do not go onto use hard drugs; marijuana is more properly viewed as a strainer that catches most illicit drug users and they go no further. The numbers bear out these findings: According to the federal government 76.3 million people have tried marijuana, while only 2.78 million have ever tried heroin in their lifetimes and only 5.3 million have ever tried cocaine in their lives. The figures for monthly use are similar: 10.7 million Americans admit to being regular marijuana users, yet only 1.2 million admit to using cocaine each month - 1 for every 9 marijuana users - and 130,000 people use heroin monthly, or 1 for every 80 regular marijuana users.

[Substance Abuse and Mental Health Services Administration, US Dept. of Health and Human Services, National Household Survey on Drug Use 2000 (Washington, DC: SAMHSA, 2001]

The Journal of the American Medical Association features an article on 'gateway theory' in its Jan. 22/29, 2003 edition. According to the article, "Early Onset of Drug Use in Early-Onset Cannabis Users vs. Co-twin Controls," " While the findings of this study indicate that early cannabis use is associated with increased risks of progression to other illicit drug use and drug abuse/dependence, it is not possible to draw strong causal conclusions solely on the basis of the associations shown in this study."

Indeed, according to the study's authors:
"Other mechanisms that might mediate a causal association between early cannabis use and subsequent drug use and drug abuse/dependence include the following:
"1. Initial experiences with cannabis, which are frequently rated as pleasurable, may encourage continued use of cannabis and also broader experimentation.
"2. Seemingly safe early experiences with cannabis may reduce the perceived risk of, and therefore barriers to, the use of other drugs. For example, as the vast majority of those who use cannabis do not experience any legal consequences of their use, such use may act to diminish the strength of legal sanctions against the use of all drugs.
"3. Alternatively, experience with and subsequent access to cannabis use may provide individuals with access to other drugs as they come into contact with drug dealers. This argument provided a strong impetus for the Netherlands to effectively decriminalize cannabis use in an attempt to separate cannabis from the hard drug market. This strategy may have been partially successful as rates of cocaine use among those who have used cannabis are lower in the Netherlands than in the United States."
(Emphasis above added by CSDP Webmaster.)

Indeed, rather than cannabis, the research seems to point to early use of tobacco or alcohol as more of a predictor of later use of other drugs and of later problem drug use. The report notes that "While covariates differed between equations, early regular use of tobacco and alcohol emerged as the 2 factors most consistently associated with later illicit drug use and abuse/dependence. While early regular alcohol use did not emerge as a significant independent predictor of alcohol dependence, this finding should be treated with considerable caution, as our study did not provide an optimal strategy for assessing the effects of early alcohol use."

Unsurprisingly, this research is being misreported in the popular press, see for example this article from the Boston Globe on Jan. 22, 2003, "Study On Twins Supports View Of Marijuana As A Gateway Drug." Fortunately, the article itself is available free online, and also a PDF of the full article is stored in the CSDP research section, along with a PDF of an accompanying editorial.

The Institute of Medicine in 1999 dismissed the ‘gateway’ theory:

"There is no conclusive evidence that the drug effects of marijuana are causally linked to the subsequent abuse of other illicit drugs."

Source: Joy, Janet E., Stanley J. Watson Jr., and John A. Benson Jr., Division of Neuroscience and Behavioral Research, Institute of Medicine, "Marijuana and Medicine: Assessing the Science Base (Washington, DC: National Academy Press, 1999).

The IOM report went further:

"Patterns in progression of drug use from adolescence to adulthood are strikingly regular. Because it is the most widely used illicit drug, marijuana is predictably the first illicit drug most people encounter. Not surprisingly, most users of other illicit drugs have used marijuana first. In fact, most drug users begin with alcohol and nicotine before marijuana - usually before they are of legal age."

Source: IOM, "Marijuana and Medicine: Assessing the Science Base," 1999.

Distortion 7: Gateway Theory