Changing brains and minds on a changing planet

A traditional Chinese proverb says that “each region’s water and soil raises its own kind of people.” In its most literal interpretation, it is taken to mean that culture is shaped by physical environments. Newer interpretations have expanded to consider not only the influence of the environments in which we live but also the social determinants or conditions that affect our individual development, physical and mental health, and wellbeing.

For the majority of the planet’s inhabitants who dwell in urban regions, the focus on literal water and soil has been supplanted by a focus on built environments and infrastructure associated with urbanization. China demonstrates this vividly, as the percentage of the population living in urban areas has risen from under 20% in the mid-1970s to about 68% at present. With this prolific expansion of urbanization has come the rise of ‘megacities’, or metropolitan areas with populations of over 10 million, such as Beijing and Shanghai.

Megacities pose unique challenges as rapid population increases put strain on existing infrastructure, such as power grids and public transportation. Innovations in architecture, commerce and technology that have made urbanization and megacities possible have accelerated the consumption of natural resources and have produced massive waste and pollution, with a substantial impact on those most basic elements of air, soil and water.

The effects of the ‘take–make–waste’ model involved in ever-expanding built environments are compounded by climate change, which intensifies extreme weather patterns and produces cycles of drought and flooding, erosion and subsidence. Climate change and urbanization can interact to precipitate urban heat islands through reduced green space and more asphalt and concrete, and concentrated anthropogenic activities such as vehicle emissions and the use of air conditioning.

Appreciation of the enormity of climate, environment and urbanization interactions requires, at least temporarily, zooming out to a macro scale. But attempting to understand how these broad regional and global trends affect physical and mental health in specific populations and even individual people demands a different perspective and set of tools, some of which we may not yet have. With that quandary as a backdrop, Nature Mental Health convened the Earth–Brain–Health Commission in 2024. After 2 years of meetings, deliberation, writing and refining, the Commission Report is published and included in the November 2026 issue.

The Commission Report proposes what might be considered a fundamentally cross-disciplinary approach to the study of mental health predicated on the dynamic interrelationships of brains, bodies, societies and physical environmental systems. By placing brain health and mental health within the broader context of environmental change, it moves beyond the prescription of a single research agenda in favor of mapping out a conceptual framework for guiding future research.

This systems perspective represents a substantial expansion of the field. The Earth–Brain–Health framework broadens the framing of social determinants of mental health by integrating environmental, climate and technological determinants into a common explanatory model. In doing so, it aligns with other emerging research paradigms, such as the exposome and planetary health, while preserving the unique contributions of neuroscience and psychiatry.

Making the case for this framing, the Commission Report considers the proliferating body of work that supports the linkages between changing and deteriorating environmental conditions, such as pollution, increasing temperatures, and exposure to natural disasters, and adverse mental health outcomes. Equally importantly, if not more so, the report synthesizes where there are gaps in the research. The majority of studies investigating environmental exposures and mental health have been observational in nature, which precludes determining causality. Individuals and populations are not randomly adversely exposed; factors such as underlying health status, socioeconomic position, and migration or displacement can dictate where a person lives and their level of risk. Research often considers associations with specific risks, although individuals who are at risk seldom experience exposures in isolation, such as living in a higher population density area with greater pollution and ambient heat. (For more discussion of this topic, please also see the Comment by Gramann et al. in this issue.)

Where substantial research gains can be made is in linking biological responses to environmental change with brain health and mental health. While evidence implicates pathways that involve inflammation, stress physiology, sleep disruption, cardiovascular function and direct neurotoxic effects, the relative importance of these mechanisms probably varies across populations and exposures. Integration of more representative and longitudinal epidemiology with other approaches, including neuroimaging, genomics and epigenomics, will be needed to establish mechanistic models that can inform prevention and intervention strategies.

The commission reframes environmental change from purely a stressor that contributes to psychiatric burden instead to a central determinant of brain development, cognitive aging and mental health across the lifespan. This change has practical implications for urban planning, climate adaptation, housing policy and biodiversity conservation to be considered as interventions with direct effects on mental health. The Commission Report’s accompanying Policy Brief underscores the fact that mental health and wellbeing are core aspects of resilience and, consequently, should be measured, aggregated and embedded in multisectoral public policy and preparedness plans and should be reported alongside economic and social progress indicators.

Commissions, like research agendas and roadmaps, are valuable mainly for their ability to generate measurable progress. The limitations of existing research underscore the value of the commission process. Now codified, the recommendations provide a comprehensive standard for benchmarking what comes next, from fragmentation to a cumulative science-guiding policy. For mental health research, success may look like the convergence of disciplines that have been concerned mainly with reacting to illness, into a powerful, anticipatory and adaptive effort to improve environmental and social conditions to shape healthier brains and human flourishing.