A new study on drug use patterns in Japan raises additional doubts about the idea that marijuana is a gateway drug. The research concluded that cannabis consumption in the country generally occurs after the initiation of alcohol and tobacco use — and that, in most cases, it does not lead to the use of other substances.

Published in the Neuropsychopharmacology Reports journal, the survey is described by the authors as "one of the largest and most significant studies on community cannabis users in Japan to date".

Nearly Half of Cannabis Users Did Not Try Other Drugs

The research revealed that nearly half of the respondents who reported using marijuana as a third substance "did not move on to using other drugs after that". The report, supported by the Japanese Clinical Cannabinoid Association and the Ministry of Health, Labor and Welfare of Japan, states:

"Cannabis use in Japan generally occurs after alcohol and tobacco consumption, and rarely leads to subsequent drug use. These findings challenge the gateway hypothesis in the Japanese context".

Social Factors and Restrictive Policies Shape Usage Patterns

While acknowledging that cannabis is often labeled as a "gateway drug", the study highlights the lack of strong causal evidence on progression to the use of other substances. Instead, the data suggest that "shared vulnerabilities" — such as age, education, and socioeconomic status — as well as strict drug policies, shape these behaviors.

The research was conducted through an anonymous questionnaire in January 2021, with 3,900 people who had previously used cannabis. The researchers analyzed the chances of participants using other substances after their first contact with marijuana.

According to the authors, the chances of subsequent use of alcohol, tobacco, methamphetamine, and other illicit drugs after cannabis were, respectively, 1.25, 0.77, 0.08, and 0.78 — suggesting a low probability of progression.

Although 10.4% of marijuana users reported having used methamphetamine — a percentage higher than the national average of 0.5% — the study emphasizes that this does not imply causality.

Illicit Market and the Common Liability Theory

The report supports the so-called "common liability theory", which proposes that the order of substance use does not result from a causal effect between them, but from shared genetic, social, and psychological factors that predispose individuals to multiple use.

"In Japan, strict regulations on cannabis can create a scenario where it circulates in the same market as other illicit drugs, increasing users' exposure".

The research also observed lower rates of legal substance use, such as benzodiazepines and prescribed medications, among participants.

Study Limitations and Next Steps

The authors acknowledge methodological limitations, such as recruitment through social networks and the exclusive focus on individuals who had already used cannabis. Therefore, they recommend large-scale cohort studies with the general population.

Nevertheless, the results are clear: "We did not observe patterns supporting the gateway drug hypothesis".

Content originally published on MarijuanaMoment