A new systematic review of 172 studies including data from over 12 million adolescents across 166 countries reveals that while cross-national adolescent mental health research including low- and middle-income countries has expanded significantly, large gaps remain in global representation.

The systematic review, conducted by an international research team led by the Research Centre for Child Psychiatry at the University of Turku, Finland, found that inclusion of low- and middle-income countries (LMICs) in cross-national research has increased dramatically over the past 30 years, especially since 2020. However, 52 countries were not included in any of the 172 studies reviewed.

Most research relies heavily on cross-sectional, school-based surveys with self-reported questionnaires. The most commonly used international surveys were the Health Behaviour in School-aged Children study (19.8%), the Global School-based Student Health Survey (12.2%), and the Programme for International Student Assessment (8.1%).

The review reveals that while bullying and internalising problems, such as anxiety and depression, are commonly studied, externalising behaviours like aggression are often overlooked. While the prevalences of most mental health and psychosocial issues were comparable or mixed between LMICs and high-income countries, traditional bullying was reported more frequently in LMICs in the majority of reviewed studies.

Western standards pose methodological challenges for global mental health research

The lead authors, Doctoral Researcher Xiao Zhang and Postdoctoral Researcher Yuko Mori, highlight a major methodological challenge revealed by the review.

“Many of the commonly used tools were originally developed based on Western mental health constructs. This raises concerns about their validity and relevance when applied across culturally diverse settings”, they explain.

Professor Andre Sourander, Director of the Research Centre for Child Psychiatry, agrees that our understanding about adolescent mental health still relies heavily on research findings from Western or high-income countries.

“Global trends, such as increased inequalities, migration, and climate change, emerging threats, such as war and pandemics, and enormously increased use of digital devices may have detrimental effects on adolescent well-being worldwide. Cross-cultural research on adolescent mental health including diverse societies, minorities and risk groups is highly relevant and warranted, especially since 90 percent of the global adolescent population resides in low and middle-income countries”, Professor Sourander emphasises.

The researchers stress the importance of creating and validating their own culturally grounded instruments in LMICs, which could also enrich mental health research in high income countries by offering more inclusive and globally applicable assessment frameworks. Future studies, they argue, should employ validated tools, use multiple informant sources, and draw on representative samples that include minority populations, such as adolescents from immigrant backgrounds, those with disabilities, and indigenous groups.

This systematic review was funded by the INVEST Flagship programme of the Research Council of Finland and the European Research Council under the European Union’s Horizon 2020 research and innovation programme.

The review titled “Cross-national research on adolescent mental health: a systematic review comparing research in low, middle and high-income countries” was published in the journal BMJ Global Health on 25 July 2025.