Reflections on the current status of psychiatric epidemiology and public mental health

In October 2024, our WPA Epidemiology and Public Health Section organized a meeting in Bangkok, Thailand. This was the 20th meeting of our Section, founded in 1967, which for decades has convened psychiatric epidemiologists together to share research and develop collaborations. In this meeting, we engaged scientists from 33 countries across six continents. The theme was “Changing environments, well-being and population mental health”, reflecting the speed and scale of change across the world which is affecting population mental health. Since its origins, psychiatric epidemiology has grappled with measurement of mental health conditions and methods to assess their population distribution, causes, correlates and outcomes. Debates still unfurl over what constitutes mental health, and the reliability, validity and utility of our diagnostic systems1. These discussions are especially useful when involving colleagues from countries and cultures with different norms, health systems, and ways of thinking and being. Within these long-standing debates, interest in mental health and its determinants has been galvanized in recent years, due to a confluence of factors, including the COVID-19 pandemic2, the rise of social media, the visible impacts of climate change3, and increases in global conflicts, displacement and forced migration. Indeed, increases in mental health and distress in recent years have been documented in many countries. The role of psychiatric epidemiology has thus never been more important, in that designing rigorous studies aimed at accurate, comprehensive and population-based assessments of disorder and distress is critical to documenting the scope and magnitude of these problems and the potential interventions to address them. Collecting data on these phenomena has never been more possible, and yet never been more challenging. More possible, because across the world there are now many new streams of data. We have greater access to electronic health records, linked population registries, and digital devices that track our steps, sleep and heart rate, and provide accessible modalities for querying populations about their mood and stressors. Moreover, major efforts are ongoing to collect large databases for genetic sequencing. More challenging, because fundamental issues of selection bias, undefined target populations, and incomplete phenotyping threaten the validity and utility of the science that we produce using these exceptionally large resources. Further, we are called to improve the ethical conduct of our research in people most vulnerable to exploitation and harm4. All this leads to a fundamental question: what is psychiatric epidemiology today, and what do we want to be as a field? In part, we are the field of counting – counting the ill, counting lives lost. We are also the field tasked with identifying the causes of these counts within and across populations. In that sense, we are also tasked with solidifying the frame of what we will theorize, measure and analyze as potential causes. New tools for identifying the biological underpinnings of brain and behavior are exciting developments for psychiatric epidemiology. Yet, among the many themes of our meeting in Bangkok, a renewed challenge to seriously consider social determinants of health emerged as paramount. In many countries there are legacies of conflicts, war and oppression, and political regimes that have expanded or contracted their people's ability to make meaningful connections and develop resources for families and communities. Indeed, it is evident that the social determinants of mental health are quite similar across countries and cultures5. Those exposed to trauma, to poverty, to instability at home and in their communities have increased risks of a wide range of psychiatric disorders, from depression and anxiety to post-traumatic stress disorder and psychosis. The differences within and across countries are often in the prevalence of these experiences, based on the political regime, on response to poverty through national policy, and on public and medical health systems that provide service resources for those affected. Global conflicts remain in the forefront not only of our scientific discussions, but also of our scientific community. The effects of recent political violence on the incidence of trauma and psychiatric disorders in many regions across the world contribute in fundamental ways to current population mental health. The legacies of global conflict on our scientific understanding of social determinants of mental health is just one part of the story, however. As scientists, we are charged with providing rigorous methods by which humanity's experiences of these events can be documented, but often we are experiencing the events ourselves in our communities. Conducting research in these circumstances is often both vital and dangerous for researchers themselves. Data collection efforts across the world were disrupted due to the COVID-19 pandemic, and members from currently conflict-affected regions cannot participate in our meetings for safety reasons. This instability limits our ability to bear witness to suffering, in both the scientific literature and in exchanging scientific ideas with our peers. A letter to the editor published in the British Journal of Psychiatry6, that was quoted at our meeting in Bangkok, criticized a study of psychiatric patients’ symptoms after nights of rioting in Belfast in 19697. These riots occurred amid The Troubles, a 30-year period of political violence in Northern Ireland that had profound psychological consequences, elevating levels of mental disorders across multiple generations. The author of the letter criticized the study based on the lack of a systematic random sample, and the potential for selection bias therein. The author of the study responded with a stunning turn of phrase: “If one were to attempt a random sample in these circumstances, one might well encounter a random bullet”. Like in Belfast during The Troubles, psychiatric epidemiological research has to be conducted while navigating complex political landscapes, avoiding sometimes metaphorical and sometimes literal bullets8. In conflict-affected regions, understanding complex historical and social contexts is essential for both the safety of researchers and the validity of findings. Yet, there is tremendous promise for the future of psychiatric epidemiology across the world. Innovations in digital technology for collecting data and delivering interventions across the world, even in the most marginalized places, hold promise for our abilities to make a difference. In our meeting we learned about innovative new technologies9, with high-caliber science applying a critical eye towards assessment and validity. We are in a different world as we emerge out of the global pandemic, and psychiatric epidemiology must continue to shift alongside the needs of the populations that it serves. Within these changing environments, however, central truths remain that those with less power, resources and opportunities are those most affected by mental health problems, and that these imbalances often persist across generations and can be enhanced in periods of conflict. Our ability to conduct rigorous research has to adapt to these realities, while maintaining ethical standards and scientific integrity. It requires innovative methodologies that balance scientific rigor with sensitivity to vulnerable communities, and must be coupled with a commitment to translating findings into actionable policies that promote mental health equity.