Between 2016 and 2024, despite increases in tolerant attitudes toward cannabis and experiences of being offered drugs, the lifetime prevalence of controlled drug use among Japanese adolescents declined, reaching 0.2% in 2024. Key risk factors included permissive attitudes, perceived ease of access, lifestyle disruptions, and social isolation, particularly when multiple risk factors overlapped.

During the study period, the lifetime prevalence of controlled drug use among Japanese adolescents aged 12–15 years declined from 0.5% to 0.2%. This trend was consistent across all major substances and remained robust after adjusting for grade and sex. Over the same period, permissive attitudes toward drug use generally declined, although tolerance toward cannabis increased slightly. The proportion of students who perceived drugs as easily accessible decreased, whereas reports of being offered drugs showed a modest increase.

Even though the risk of being offered drugs increased, ¹⁴ , ⁴¹ , ⁴² , ⁴³ , ⁴⁴ , ⁴⁵ , ⁴⁶ , ⁴⁷ , ⁵⁶ , ⁵⁸ , ⁵⁹ , ⁶⁴ , ⁶⁵ , ⁶⁶ , ⁶⁷ , ⁶⁸ actual drug use continued to decline. This seemingly paradoxical trend may reflect the growing influence of protective factors, such as strong internalized norms against drug use, increased health awareness, and early preventive education. The low prevalence may be attributed to a combination of strict drug control laws (e.g., criminalization of drug use), sustained school‐based prevention programs, societal disapproval, and pervasive social stigma, all of which likely act as deterrents to adolescent drug use. ⁵⁷ , ⁶⁹ , ⁷⁰ , ⁷¹ In other words, even when adolescents are exposed to interpersonal risks, they may resist drug use due to reinforced personal values and strong societal norms. In our survey, more than 97% of students expressed opposition to drug use (Table 2), suggesting that abstinence may reflect not only behavioral restraint but also deeply rooted personal convictions and socially reinforced norms. It is also plausible that reduced peer interaction during the COVID‐19 pandemic contributed to the sharp decline observed in 2024, although this remains speculative.

While overall exposure to drugs appears to be declining, several concerns warrant attention. The slight increase in reports of drug offers suggests that some adolescents remain in high‐risk social environments. Simultaneously, the modest rise in cannabis tolerance may be influenced by global legalization trends and increased online exposure to cannabis‐related content. ¹⁶ , ²⁴ , ⁶⁷ , ⁷² , ⁷³ , ⁷⁴ These findings highlight that despite general improvements, specific subgroups may continue to face elevated risks due to their social context and evolving perceptions of certain substances.

Additionally, minor increases were observed in lifestyle disruptions, such as irregular sleep, skipping breakfast, and spending unsupervised time, all of which were significantly associated with drug use in this and prior studies. ³⁶ , ⁷⁵ , ⁷⁶ , ⁷⁷ , ⁷⁸ , ⁷⁹ These behavioral changes may reflect broader societal shifts, including the rise in dual‐income and single‐parent households, ⁴⁸ potentially resulting in reduced parental oversight.

Drug use among adolescents was associated with male sex, prior alcohol or tobacco use, permissive attitudes toward drug use, perceived ease of access, and experiences of being offered drugs. Lifestyle disruptions and weak connections with family and school were also identified as key risk factors. These findings align with those of previous studies conducted in Japan and internationally, ¹⁴ , ⁴¹ , ⁴² , ⁴³ , ⁴⁴ , ⁴⁵ , ⁴⁶ , ⁴⁷ , ⁵⁶ , ⁵⁸ , ⁵⁹ , ⁶⁴ , ⁶⁵ , ⁶⁶ , ⁶⁷ , ⁶⁸ suggesting that adolescent drug use may be driven more by psychosocial vulnerabilities than by individual choice alone.

This study highlights the importance of weak family and school connections as significant contributors to adolescent drug use. Consistent with earlier findings, being offered drugs was strongly associated with actual use. While past research has emphasized the role of delinquent peers in promoting drug use, ⁴⁹ , ⁵⁰ , ⁸⁰ , ⁸¹ the present findings—emphasizing both social isolation and drug offers—may appear somewhat inconsistent with the existing literature.

Several factors may help explain this discrepancy. In addition to the conventional pressure exerted by delinquent peer groups, socially isolated adolescents may be drawn to deviant groups as a means of seeking emotional connection or belonging. ⁸² , ⁸³ Prior studies have shown that involvement in such groups can offer a sense of acceptance or a place to “fit in.” ⁵¹ , ⁵⁵ , ⁸⁴ Moreover, in contexts where adolescents lack supportive family or social relationships, psychological vulnerabilities, such as low self‐esteem or anxiety, may play a role. Under such conditions, being offered drugs may not only present a behavioral opportunity but also be perceived as a temporary source of comfort or escape.

This study observed that the co‐occurrence of three social disconnection factors—school dissatisfaction, lack of casual friends, and limited communication with parents—was associated with a substantially higher likelihood of drug use. Specifically, the odds ratio for students experiencing all three conditions was 9.63. Table S3 indicates that the prevalence of drug use among this subgroup was 3.34%, compared to 0.25% among students without any of these risk factors a more than tenfold difference. These findings suggest that multiple forms of social isolation may have a cumulative impact on vulnerability to drug use. Furthermore, the results from Model B and its simplified version indicated that having at least one positive connection with school, peers, or parents was associated with lower odds of drug use. It is important to note, however, that the number of students reporting all three disconnection factors was relatively small (n = 68), and the 95% confidence interval for the corresponding interaction term was wide (1.60–57.93). This limits the precision of the OR estimate; thus, the findings should be interpreted with caution. Nonetheless, identifying such high‐risk subgroups remains important from a public health perspective, underscoring the value of targeted interventions for adolescents facing multiple psychosocial vulnerabilities.

Furthermore, the findings from Models B and C suggest that both emotionally close relationships and relatively casual social ties may offer protective effects. These observations underscore the importance of promoting diverse opportunities for social engagement as a strategy to prevent adolescent drug use.

Between 2016 and 2024, improvements were observed in school satisfaction, peer relationships, and parent–child communication among Japanese adolescents. Despite these positive trends, difficulties in interpersonal relationships remained significantly associated with drug use. This suggests that enhancements in the overall social environment may not be sufficient to protect all adolescents, particularly those experiencing persistent social disconnection. One possible explanation is that such individuals may not fully engage with or benefit from existing support systems if these are perceived as emotionally unsafe, inaccessible, or untrustworthy. In this study, students who rarely or never consulted their parents or friends were significantly more likely to report drug use. This suggests that at‐risk adolescents may be less inclined or less able to seek help or initiate communication during times of difficulty. Although these perceptions were not directly assessed in this study, previous research has emphasized the importance of adolescents' subjective experiences in shaping the effectiveness of school‐ and family‐based interventions. ⁸⁵ , ⁸⁶ , ⁸⁷ Taken together, these findings imply that preventive strategies should not only address peer norms and provide structural support but also foster a sense of belonging and emotional safety within school and family environments. ⁵⁸ , ⁸⁵ , ⁸⁸ , ⁸⁹ Moreover, the provision of alternative drug‐free environments, such as community‐based settings that facilitate non‐judgmental peer interactions, may offer critical support for socially isolated adolescents and reduce their susceptibility to drug use.

This study was a design‐based cross‐sectional analysis; therefore, its conclusions are limited to individual‐level associations. Even with that caveat, patterns observed in Japan may be informative for other low‐prevalence settings (e.g., South Korea and parts of the Middle East). ³⁸ , ³⁹ In such contexts, stringent drug laws, strong social disapproval, and internalized anti‐drug norms may contribute to lower prevalence. ⁹⁰ In Japan, conservative cultural norms alongside institutional prevention efforts may also deter initiation. ⁹¹ By contrast, higher‐prevalence countries (e.g., the United States and parts of Europe) often report greater adolescent use in tandem with sensation‐seeking, peer normalization, and more permissive attitudes toward cannabis, trends shaped in part by legalization and media narratives that may weaken traditional deterrents. ⁹² , ⁹³ , ⁹⁴

At the same time, our findings suggest that structural protections are not sufficient for all adolescents. Youth with weak connections to family, school, or peers, particularly those who rarely communicate with their parents or report low school satisfaction, are more likely to report drug use. Similar patterns have been observed in the United Arab Emirates, where socially isolated adolescents face increased risks despite strong legal and cultural controls. ⁹⁵ These findings underscore the need to complement legal frameworks with interventions that foster emotional connection and support. ¹³ , ⁵¹ , ⁸⁵ , ⁹⁶ , ⁹⁷ , ⁹⁸ , ⁹⁹

Overall, the findings suggest that strategies in low‐prevalence countries should not only focus on maintaining structural and legal deterrents but also prioritize the betterment of adolescents' emotional well‐being and sense of connectedness within family and school environments. Complementary measures, such as the provision of community‐based, drug‐free settings where adolescents can form meaningful relationships, may support those less likely to be reached through traditional prevention programs.

Finally, as this is a cross‐sectional study, causal inference is not possible, and structural factors were not directly measured. Future research should test these hypotheses using designs that incorporate contextual indicators (e.g., enforcement, availability, socioeconomic conditions).

This study has some limitations. All data were self‐reported and may be subject to recall or social desirability bias. Key confounders, such as parental substance use, mental health status, and family background, were not assessed. The cross‐sectional design precludes causal interpretation, and some subgroup analyses may have lacked statistical power. Selection bias is also possible, as non‐participating students may differ systematically from those included in the sample. Finally, the 2024 wave was administered in mixed modes (paper and a secure web platform). Potential response‐mode effects on self‐reports cannot be fully ruled out.

Although this study focused on illicit drugs, the increasing misuse of legal substances among Japanese adolescents, such as over‐the‐counter and prescription medications, has become a growing concern with increasing rates of overdose and addiction. ⁵⁷ , ¹⁰⁰ , ¹⁰¹ These trends, observed in other countries as well, ¹⁰² , ¹⁰³ , ¹⁰⁴ highlight the need for broader surveillance systems that capture both legal and illegal substance use to protect at‐risk youth.

Controlled drug use declined among Japanese junior high school students between 2016 and 2024, but remained concentrated among those with disrupted daily routines and indicators of social isolation. These findings underscore the need for targeted prevention interventions, even in low‐prevalence settings.