Stressful life events are unexpected situations that disrupt routines and emotional stability, ranging from parental divorce and financial hardship to physical, psychological or sexual abuse, the death of a close person, bullying and community violence. Globally, an estimated one-quarter of people experience between one and three such events over their lifetimes, while roughly 10 percent report four or more. Previous research has shown that events experienced in childhood and adolescence can cast a long shadow over later physical and mental health, with documented associations extending to obesity, hypertension, depression, alcoholism and psychoactive substance consumption. The life course perspective offers a framework for understanding these links: health and behavior are shaped by experiences embedded in cumulative trajectories across the lifespan, rather than by isolated incidents, with the timing, accumulation and social context of early exposures all influencing later outcomes.

Substance use typically begins in adolescence and becomes more frequent in young adulthood. Worldwide, 48.4 percent of individuals experience the onset of any mental disorder before the age of 18, with a peak age of onset at 14.5 years, while substance use and addictive behavior disorders peak at approximately 19.5 years. In Argentina, Colombia and Peru, at least 30 percent of adolescents report having consumed a psychoactive substance in their lifetime. Yet the authors of the new study identified two important gaps in the existing literature. Most commonly used instruments to measure stressful life events evaluate only abuse and family dysfunction, despite recommendations to include a broader list covering bereavement, bullying and community violence, especially in low- and middle-income countries. In addition, most studies have focused on legal substances such as alcohol and tobacco, leaving less evidence on marijuana, cocaine or opioids even as their consumption grows among young people.

To address these gaps, the research teams from the Pontificia Universidad Javeriana, the University of Buenos Aires and the CRONICAS Center at Universidad Peruana Cayetano Heredia recruited participants between April 2021 and November 2022 as part of the OLA Programme, which investigates resources that help young people in deprived urban areas prevent and recover from depression and anxiety. Participants were adolescents aged 15 to 16 and young adults aged 20 to 24 from families in districts falling within the bottom 50 percent on the Human Development Index in Colombia and Peru, or the Unsatisfied Basic Needs Index in Argentina. Recruitment combined in-person visits to schools, community organizations and educational centers with virtual strategies, including social media advertising in Lima, reflecting each country’s pandemic-era regulations. Individuals with diagnosed severe mental disorders, learning disabilities or an inability to read and write were excluded.

The exposure was measured with an adaptation of the Adolescent Appropriate Life Events Scale, a self-report instrument covering 30 events that occurred more than a year before the survey. Because no standardized cut-off points existed, the researchers divided the counts into tertiles: zero to five events as the reference category, six to nine as the middle group, and 10 to 22 as the highest. Substance use in the last three months was self-rated using questions from the World Health Organization’s Alcohol, Smoking and Substance Involvement Screening Test, whose validated Spanish version showed adequate reliability with a Cronbach’s alpha of 0.93. Six dichotomous outcomes were analyzed independently: tobacco, alcohol, marijuana, tranquilizers, other drugs such as cocaine, amphetamines, inhalants, hallucinogens and opioids, and the use of three or more substances, which served as a proxy for a more complex pattern of use rather than a marker of clinical severity.

The statistical approach was deliberately conservative. The researchers constructed a directed acyclic graph to identify candidate confounders, including gender, age group, country of residence, education level, distress lasting at least 30 consecutive days, participation in sports, youth, artistic or religious groups, resilience measured with the Connor-Davidson Resilience Scale-10, and perceived social support measured with the Multidimensional Scale of Perceived Social Support-12. Crude and adjusted prevalence ratios were estimated using generalized linear models of the Poisson family with log link and robust variances, and a significance threshold of p below 0.001 was adopted to reduce the risk of type I error across the six simultaneous comparisons. Analyses used complete cases only, and variance inflation factors confirmed that multicollinearity was not a concern in any model.

The results revealed a heavy burden of adversity. The median number of stressful life events was six among adolescents and seven among young adults, and 24 of the 30 events were reported by at least 10 percent of participants. The most frequent were having a family member victimized by assault or robbery at 53.5 percent, parental separation at 44.0 percent, being personally victimized by assault or robbery at 43.4 percent, the death of a close person at 42.2 percent, physical or psychological bullying at 39.7 percent, ongoing family financial problems at 36.2 percent and sexual harassment at 23.3 percent. In the last three months, 54.9 percent of participants had used alcohol, 18.8 percent tobacco, 11.8 percent marijuana, 5.6 percent tranquilizers and 1.9 percent other psychoactive substances, while 9.5 percent had used three or more substances. Polysubstance use varied strikingly by country, reaching 19.5 percent in Argentina, 7.9 percent in Colombia and 3.7 percent in Peru.

After adjustment, experiencing 10 to 22 stressful life events compared with zero to five was associated with a higher prevalence of use in four of the six outcomes: tobacco with a prevalence ratio of 1.69 (95 percent confidence interval 1.37 to 2.08), alcohol with 1.23 (1.13 to 1.35), marijuana with 1.75 (1.35 to 2.26) and three or more psychoactive substances with 1.85 (1.35 to 2.53), all at p below 0.001. No statistically significant associations emerged for tranquilizers or other drugs. When each of the 30 events was examined individually against polysubstance use, 13 associations were significant, with the strongest prevalence ratios observed for having lived on the street at 2.17, having been expelled from school at 2.00 and having been suspended from school at 1.87. The authors suggest these events may act as indicators of social exclusion and lack of social support, with street exposure also placing young people in environments where substances are more common and accessible. Post hoc interaction analyses found no significant differences between adolescents and young adults, hinting that the relationship may be relatively consistent across both age groups, though limited statistical power means small interaction effects could have been missed.

The researchers propose several mechanisms for the link. Stressful life events may leave a lasting imprint on emotional, cognitive and social development, making young people vulnerable to risky behaviors. Substances may be used as a way to temporarily alleviate the emotional distress caused by traumatic events, producing relaxation and euphoria that help avoid thoughts and emotions connected to the adversity. Those affected may also assign greater value to short-term rewards such as substance use over long-term rewards like seeking help. The polysubstance finding aligns with prior evidence that family dysfunction, parental abuse and neglect are associated with concurrent use of multiple substances, and that most adolescents who use marijuana first used tobacco or alcohol, with marijuana use associated with subsequent use of other illicit drugs.

The study’s strengths include its large sample from three South American countries and its comprehensive list of events spanning family dysfunction, abuse and community violence, which has been specifically recommended for low- and middle-income contexts. However, the authors caution that convenience sampling may limit representativeness, that all measures were self-reported and vulnerable to recall and social desirability bias, and that the cross-sectional design cannot establish cause and effect, even though events were assessed for the period more than a year before the survey while substance use covered the past three months. The frequency and perceived severity of events were not evaluated, individuals with severe mental disorders were excluded, which may have led to underestimation of the true association, and the study lacked power for country-stratified analyses. Tobacco questions did not cover e-cigarettes. Unmeasured confounding and residual confounding cannot be ruled out.

From a public health standpoint, the findings support early identification of young people carrying a high cumulative burden of adversity, so that interventions can be implemented before substance use trajectories consolidate. With prevention budgets severely limited in South American countries such as Peru, the authors argue that strategies should prioritize youth exposed to multiple or severe events. Evidence shows bullying can be reduced through well-coordinated anti-bullying policies with clear definitions, guidelines and sanctions. Strengthening social support networks, promoting involvement in sports, artistic and religious groups, and improving the quality of parent-child relationships could buffer the long-term effects of early adversity. More support for young people and their families at risk of school suspension or expulsion may be particularly valuable, as these events appear to represent critical turning points with long-term implications for substance use.

Subject of Research: Association between stressful life events and psychoactive substance use in adolescents and young adults from Argentina, Colombia and Peru

Article Title: Association between stressful life events and psychoactive substance use in adolescents and young adults from Argentina, Colombia and Peru

Article References: Paredes-Angeles, R., Lazo-Porras, M., Carbonel, A., Gómez-Restrepo, C., Brusco, L. I., Sureshkumar, D. S., Uribe-Restrepo, J. M., Olivar, N., Fung, C., Esnal, F., Godoy-Casasbuenas, N., Priebe, S., & Diez-Canseco, F. (2026). Association between stressful life events and psychoactive substance use in adolescents and young adults from Argentina, Colombia and Peru. BMC Psychiatry, 26(1), Article 822. https://doi.org/10.1186/s12888-026-08357-7

Image Credits: AI Generated

DOI: 10.1186/s12888-026-08357-7

Keywords: stressful life events, substance use, adolescents, young adults, Latin America, Argentina, Colombia, Peru, BMC Psychiatry, cross-sectional study, polysubstance use, public health