Youth substance use: Current trends and prevention paths

The use of alcohol and nicotine products and the non-medical use of ­prescription medications and other psychoactive substances have concerned scientists for ­decades because of their well-documented negative effects on development, ­especially when initiated in adolescence. Jacobs Center researchers Prof. Lilly ­Shanahan, Assistant Prof. Carmen Villa, and PhD ­candidate Michelle Loher discuss emerging youth substance use trends and how to stay ahead of an increasingly dynamic substance marketplace.

Adolescent substance use has never been static; it evolves with culture, policy, and the environments in which young people grow up. Prof. Lilly Shanahan, Associate Professor of Clinical Developmental Psychology at the JCPYD, emphasizes that the frequency of substance use among today’s youth depends on the country, the substance, and the age group evaluated. Regular moni­toring is therefore important. For example, the Zurich Youth Survey, led by Dr. Denis Ribeaud, reveals that the use of some substances, such as cigarettes and alcohol, has decreased somewhat since the late 1990s.
Yet even as some risks recede, others emerge. Vaping, non-medical use of prescription stimulants, and polysubstance consumption have grown more prevalent among young people. Shanahan and her collaborator Prof. Boris Quednow, together with a team from the UZH Institute of Forensic Medicine, have explored these trends further. In the context of the Zurich Project on Social Development from Childhood to Adulthood (z-proso), she and her collaborators employ non-invasive hair analy­sis. The technique captures objective biomarkers of sub­stance exposure, offering a window into patterns that surveys dependent on self-report can miss.

Prof. Carmen Villa is an economist whose research exam­ines how public policies (from housing to education to alcohol regulation) shape youth trajectories. In a recent paper, she examined the effects of increasing the mini­mum legal drinking age from 16 to 18, a policy adopted across many European countries, although not in all cantons of Switzerland. She found that stricter alcohol regulation improved academic performance and mental health. Prof. Villa agrees with Prof. Shanahan that there has been a steady decline in alcohol use over the last 20 years, but she highlights a shift toward highly addictive digital behaviors. As she puts it, “There is some substitution from social interactions around addictive substances to interactions on social media, which is by design very addictive.” She recommends that regulations treat social media as a substance going forward.

Michelle Loher adds that long-term and short-term patterns can look quite different: In the US, the pandemic led to a notable decline in youth initiation of nicotine, cannabis, and alcohol use, with levels not yet fully re­turn­ing to pre-pandemic figures. As a doctoral researcher at the Jacobs Center’s Risk & Resilience Lab, she examines developmental aspects of substance use and mixed-sub­stance use among adolescents and young adults. 

Shanahan notes that substance use can follow fashions, and such trends are often amplified by social media platforms that glamorize vaping or other substance use while downplaying the risks. Social media has also transformed the drug market. Dealers can recruit young customers online and deliver products to their homes or a convenient meeting point, dramatically lowering the barrier to access. Data from z-proso and wastewater analyses from cities including Zurich and St. Gallen document a notable rise in cocaine use among Swiss young adults in recent years.
The scientists also touch on the ongoing cannabis legalization debates. Shanahan explains that since the first U.S. states began legalizing recreational cannabis use, the rates of use among adults have risen to histori­cally high levels, “from about 28% to 43%.” In places where cannabis is legal, increases in psychosis and schizophrenia are emerging among vulnerable groups. Shanahan stresses that any legalization debate must grapple with youth protection. Many adolescents begin experimenting well before any legal age threshold, and brain development continues into the mid-twenties.

Curiosity, peer dynamics, stress, boredom, family be­havior, the broader social environment, and additional factors all shape the onset of substance use in adoles­cence. “The adolescent brain is curious, primed to try new things, and not consistently good at assessing risks or controlling impulses,” says Shanahan. She adds that family substance use sets early norms, and peer influence is especially strong in adolescence: Teens take more risks in the presence of peers than when alone. Some adolescents also turn to substances as a form of self-medication to cope with stress or untreated mental-health problems.

Villa emphasizes the importance of socialization and connectedness, explaining that “for adolescents, belonging is extremely important,” and linking social media use to mental-health concerns. Both she and Shanahan highlight the role of parenting; Villa notes that “more permissiveness often leads to more consumption,” based on the scarce evidence available. Shanahan observes that today’s more intensive parental supervision styles may delay early experimentation, and that delay itself can be protective. 

Shanahan emphasizes that long-term consequences reflect not only the substances themselves but also the broader context: “It’s difficult for us to say what the actual effect of the substance is versus the whole package of risk factors that adolescent substance use often comes with.” Even so, the evidence from z-proso shows that frequent and chronic cannabis use, for example, is associated with lower educational attainment, poorer pro­fessional outcomes, higher rates of delinquency, reduced well-being, and a greater likelihood of later prob­lem­atic substance use. These associations hold even when THC (the main psychoactive component of cannabis) is measured objectively in hair. Villa highlights serious short-term (i.e., acute) harms of substance use, such as accidents and victimization.

When discussing prevention, Shanahan comments that “we don’t have the golden bullet yet,” noting that broad regulations, such as reducing product accessibility, limiting the appeal of flavored nicotine products, and restricting marketing, tend to have larger population-level effects than individual behavioral interventions. She highlights that delaying the onset of use, avoiding regular or daily use, and educating youth about dangerous patterns of use may also be key for harm reduction. 
Loher stresses the importance of understanding motives, that is, asking whether youth use “to self-medicate or simply to experiment.” Villa argues for combining regulation with supportive environments, noting that “spaces for people to connect, through sports or arts, can support mental health and lower substance use.” Shanahan agrees: Such environments can help adoles­cents sustain a sense of belonging without substances as the medium.

The Jacobs Center fosters collaboration across disciplines, and all three researchers agree that substance-use research benefits from such a shared approach. Villa notes that psychology uncovers motivations and mechanisms that economists rely on to interpret policy effects. Shanahan, in turn, values the methodological rigor that economics brings. Quasi-experimental designs, often leveraging natural policy changes, can deliver causal evidence about what actually works. Economic cost-benefit analyses of prevention programs also deliver important information for policymakers, she notes. 

Together, the different approaches clarify the “why” and “how” of adolescent substance use. All three inter­viewees note that understanding substance use requires insights from multiple fields, including law, criminology, forensics, chemistry, medicine, neuroscience, public health, and sociology. z-proso already collaborates across most of these fields, which is one of the project’s defining strengths.

Reflecting on the most striking aspects of their work, all three researchers return to the same theme: constant change. As Loher notes, “It’s a complex field, and it’s constantly changing.” Shanahan puts it vividly: Substance use patterns evolve “a little bit like a virus – always mutating, always presenting new challenges for researchers trying to keep up.” Villa observes that illegal drugs are closely linked to crime, with costly and uneven societal impacts. She adds that criminality issues are “highly concentrated among a small group, disproportionately affect teenagers, and have lasting consequences,” which underscores how vulnerable they are and why early prevention is so important.

What unites these perspectives is a shared recognition that understanding adolescent substance use demands more than tracking which substances are trending at a given moment. It requires sustained attention to the social norms that shape behavior, the motivations that drive experimentation, the institutional environments that can amplify or buffer risk, and the policy levers that, used thoughtfully, can shift outcomes at a population level. The substance landscape will continue to evolve. The research agenda must evolve with it.

Author: Marta Dobrijevic
Editor: Sandro Fässler