Drug use disorders (DUDs) remain a medical issue worldwide. The increase in DUD prevalence has led to a tremendous burden on society and a sharp rise in death (1, 2). DUDs display a consistent pattern of pathological drug or substance use, which leads to recurrent negative social outcomes attributed to drug consumption. These consequences include the inability to fulfill responsibilities at work, with family or school, conflicts in interpersonal relationships, and encountering legal issues (3). Moreover, drug users are more prone to suicide and depression, and also have an increased risk of infectious diseases (4–6). As a result of the succession of adverse personal and societal consequences triggered by DUDs, it has become an indisputable crisis in public health.

Adolescence is an important stage in the development of human psychology and behavior. People in this period have a sense of self-choice and self-control. However, adolescents and young adults are susceptible to the negative influence of behavioral factors. In 2019, DUDs were the 18th leading cause of disability-adjusted life-years (DALYs) at the global level among adolescents (7). During the past few decades, DUD cases have increased by 33.5% globally, and teenagers aged 15–19 years have the highest incidence rate (8). The vulnerability of adolescents and young adults to DUDs is often affected by a range of environmental and psychosocial risk factors. These include, but are not limited to, early life adversity, peer substance use, and the co-occurrence of mental health conditions. Most adults with DUDs initiated drug use during their teenage years (9). Adolescence and young adulthood are crucial stages marked by extensive transformations in physical, cognitive, emotional, social, and behavioral aspects (10). Information on drug use patterns among youths is limited, and studies that specifically focus on the health inequalities in the disease burden of DUDs across different regions are lacking. In this case, it is important to explore epidemiological data on DUDs among adolescents and young adults.

In this study, we used data from the Global Burden of Disease (GBD) 2021 to explore the burden and health inequalities of drug use disorders in adolescents and young adults from 1992 to 2021. We describe the prevalence and disability-adjusted life years (DALYs) by region, country, sex and age group and explore the change trends using age-period-cohort (APC) model. We also analyze patterns of cross-country inequalities. This study can help design more effective policies and methods to prevent drug use disorders tailored to different regions or countries.

DUDs are serious medical problems worldwide. However, detailed information on the burden of DUDs among adolescents and young adults is still lacking. Our study reported the temporal trends of DUD burden among people aged 15–39 years at the global, regional, and national levels and assessed its health inequalities, which supplements previous publications. The prevalence and DALY rate of DUDs have notably decreased since 1992, and these trends vary considerably by sex, region and country. High-SDI regions had greater burdens of DUDs, and cross-national health inequality, as measured by the slope index and concentration index, significantly increased between 1992 and 2021. These results suggest that we should pay attention to the DUD burden among adolescents and young adults. Because adolescents and young adults are at a critical stage in both physical and mental development, targeted science education and prevention measures for adolescents and young adults are needed.

Cannabis ranks as the third most commonly used substance worldwide, after alcohol and tobacco (22). Approximately 3.9% of adults worldwide have experimented with cannabis (22). The initiation of cannabis consumption predominantly takes place during late adolescence, and there is an upward trend in cannabis usage among young individuals (23). Adolescent cannabis users may be at high risk for psychotic symptoms and neurocognitive impairments (23). Cannabis use in people younger than 18 years is associated with an increased risk of car accidents, antisocial behavior and polysubstance use (22). In 2019, 1.6 million Americans older than 12 years were estimated to have opioid use disorders and opioid overdose contributed to nearly 69 thousand deaths in the USA in 2020 (24). Additionally, there was a two-fold increase in the number of deaths caused by an overdose of cocaine, and there were one million individuals with cocaine use disorder in the United States in 2017 (25). Given the current high prevalence of DUDs and the increasing number of deaths each year, public health measures are necessary to reduce the disease burden of DUDs.

Similar to previous studies, our study demonstrated that high-income North America experienced a heightened DUD burden and that the cross-national health inequalities have increased over the past three decades. The DUD-related burden has increased in the US (26). People in high-SDI regions or countries may be more inclined to use drugs (27). However, people in low-income regions may face additional socio-economic disadvantages, such as poverty, a lack of education and poor medical care, making them highly vulnerable to mental health problems and DUDs (26). It is imperative that we allocate essential resources and undivided attention toward tackling all facets of the global drug predicament, including the provision of evidence-based care.

The rapid progression of physiological growth can impact cognitive reasoning and emotional regulation during puberty. In addition, adolescents are achieving significant developmental and life milestones, such as completing their education, embarking on a career, and striving for independence. Drug use in adolescence is linked to a somewhat elevated likelihood of experiencing depression in young adulthood (28). Adolescence and early adulthood are crucial stages when drug usage habits may form. These periods are pivotal for preventing the initiation of such behaviors, curbing the progression toward excessive drug consumption, and intervening in addressing existing substance abuse issues. Excessive cannabis consumption during adolescence has detrimental effects on cognitive functions such as memory, learning, recall, attention, problem-solving, reasoning proficiency, and intelligence. In addition to personal factors, the prognosis is worsened by accessibility to substances, socioeconomic disadvantage, peer influence, and problems in the family (29). Therefore, well-designed and implemented prevention programs for adolescents may significantly reduce the disease burden of DUDs. The allure of substance use among youth should be diminished, and access to substances to render them harder to acquire or partake in should be restricted.

While high-SDI countries generally possess more robust healthcare systems and resources, they face disproportionately high prevalence rates of DUDs. It is essential to first enhance adolescents' mental health and emotional management skills through school- and community-based initiatives. For instance, the Life Skills Training implemented in Spain may prove effective for avoiding escalation of the consumption levels of problematic drugs (30). Moreover, exercise and athletic team participation worked synergistically in lowering drug use in students (31). Second, comprehensive support, including psychological therapy, vocational training, and educational assistance, should be made readily accessible. In contrast, countries with low SDI often face challenges such as resource scarcity and underdeveloped health systems. Therefore, efforts should focus on strengthening medical infrastructure and expanding service coverage. Moreover, higher prevalence rates of DUDs can be found in unemployed people (32). Thus, it is important to create more employment opportunities for young people.

Our study has several limitations. First, the low coverage of disease reporting institutions in underdeveloped regions led to inadequate data quality, particularly in countries where there was an absence of original, high-quality epidemiological research on drug use disorders. For regions or countries without data sources, GBD estimates heavily rely on the modeling process, predictive covariates and trends from neighboring countries, resulting in some uncertainty (33). Second, DUDs in GBD 2021 include other drugs, such as hallucinogens, sedatives and tranquilizers, but epidemiological data on these specific drugs are lacking. In the future, more attention should be given to the burden of DUDs in various countries and regions. It is imperative to obtain updated regional and national data to obtain precise information of DUDs in adolescents and young adults. The economic burden caused by DUDs should also be studied in depth.

In summary, despite a decline in the prevalence and DALYs of DUDs among adolescents and young adults between 1992 and 2021, there are still cross-national health inequalities in which countries with high SDI have a higher burden of DUDs. Further investigation is necessary to determine the causes of these changes to establish effective strategies and interventions to reduce the burden of DUDs in adolescents and young adults.