A new study looking into patterns of drug use in Japan casts further doubt on the notion that marijuana is a gateway drug, concluding that cannabis use in the country usually comes after people first use alcohol and tobacco, and that they rarely go on to use other substances.
Published this month in the journal Neuropsychopharmacology Reports, the research—which authors describe as “one of the largest and most significant studies on community-based cannabis users in Japan to date”—also found that nearly half of respondents who reported marijuana as their third drug “did not go on to use other substances afterward.”
“Cannabis use in Japan typically follows alcohol and tobacco, and rarely leads to further drug use,” concludes the report, which was supported by the Japanese Clinical Association of Cannabinoids and the government’s Ministry of Health, Labour and Welfare. “These findings challenge the gateway hypothesis in the Japanese context.”
The research acknowledges that cannabis “is often labeled a ‘gateway drug,’” but it notes that “strong causal evidence for progression to other substances is limited.”
Its findings suggest that rather than cannabis use itself leading to other drug use, “shared vulnerabilities”—involving factors like age, educational background and socioeconomic status—”and strict drug policies may shape these patterns.”
The study consisted of an anonymous survey conducted in January 2021, asking 3,900 people in Japan who had used cannabis in their lifetimes about other substance use. Researchers then analyzed the data to assess the chances of people using other drugs after trying marijuana.
“Rather than implying a causal gateway effect of cannabis use,” authors wrote, “results highlight the importance of considering the broader life context in which substance use occurs. Social determinants such as age cohort, educational background, and socioeconomic position appear to shape patterns of substance progression independently of the pharmacological properties of cannabis.”
Authors’ assessment of the responses found that “Odds for subsequent use of alcohol, tobacco, methamphetamine, and other illicit drugs after cannabis use were 1.25, 0.77, 0.08, and 0.78, respectively, suggesting low probabilities of progression.”
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