If you’re interested in contributing a short What Am I Reading post, we’d love to hear from you! Email us at cache@colorado.edu

Written by Kelly Perry and Jenna Merenstein

Calling for an exposome-informed approach to brain health across the life course

Older adults are a key group at risk from climate-related threats, including extreme heat, poor air quality, and flooding (EPA). While these hazards were once primarily seen as risks to the heart and lungs, new evidence shows they also play a significant role in brain health, aging, and an increased risk of dementia (Jones et al 2025). We highlight two recent notable studies that explore the links between adverse environmental exposures and impaired brain health and aging, with a broad theme underscoring the need for more equitable, justice-centered, and exposome-informed community-level and occupational interventions to mitigating environment-related acceleration of neurocognitive aging across the life course.

What does a life course, exposome-informed, justice-centered approach to understanding and protecting brain health look like in practice? First, it demands investment in transdisciplinary research that bridges cognitive science, neuroscience, urban planning, and environmental science. Second, it requires designing policies that protect the brain from environmental harm at all stages of life—from improved maternal housing to urban greening strategies for older adults. Third, it calls for integrating neuroimaging-based measures of brain structure and brain function into exposome-focused studies to identify early biomarkers of environmental impact. Doing so would help identify targetable properties for future exposome-based intervention work and ultimately help slow or delay the negative effects of the exposome on neurocognitive aging.

A quick, non-exhaustive review of recent articles discussing adverse environmental exposures and impaired brain health, with implications for an exposome-informed life course approach

Jones and colleagues (2025) conducted an umbrella review and meta-analysis of longitudinal studies that investigated environmental risk factors for dementia, and identified that exposure to the following nine factors was associated with increased relative risk of all-cause dementia (dementia resulting from any combination of underlying causes) compared to those who were unexposed: fine particulate matter (PM; e.g., PM less than or equal to 2.5 µg/m³), particulate matter (PM less than or equal to 10 µg/m³), nitrogen dioxide (NO₂), nitrogen oxides (NO_x), carbon monoxide (CO), shift work, night shift work, chronic noise, and extremely low-frequency magnetic fields (ELF-MF). They also highlighted community-level factors that were associated with a lower relative risk for dementia, such as neighborhood greenness. Regarding specific types of dementia, Jones and colleagues found the following factors were associated with increased relative risk of dementia of the Alzheimer’s type: PM_2.5, ELF-MF, sulfur dioxide (SO₂), chronic noise, and pesticides. Similarly, PM_2.5, PM₁₀, and chronic noise were associated with increased relative risk of vascular dementia.

Canning and colleagues (2025) followed people from midlife to older age (43–69 years) to study how long-term exposure to air pollution affects the brain. They looked at common pollutants such as PM_2.5, PM₁₀, and nitrogen oxides (NO_x), and measured cognitive thinking skills and acquired brain scans (i.e., structural magnetic resonance imaging, or MRI). A strength of this study is its long follow-up period and inclusion of adults over 65—an age group that is growing quickly worldwide but often excluded from studies of environmental exposure and neurocognitive aging. The team found that people exposed to more air pollution in mid-to-late life had lower cognitive performance, slower thinking speed, and greater age-related decreases in brain volume. Compared to individuals with lower exposure to NO₂, NO_x, and PM₁₀, higher exposure to these pollutants was linked to larger brain ventricles and smaller hippocampal volume—and these changes are tied to memory abilities and overall brain health.

Interestingly, the team did not observe links between environmental exposures and measures of verbal memory, or between white matter hyperintensities (a marker for cardiovascular damage). These null findings could suggest that environmental risks may impact only certain aspects of how we think about the underlying neurobiology, although additional research is needed to confirm this. The authors also emphasize that these findings should be viewed within the bigger picture—where environmental exposures interact with genetics, cognition, and brain changes starting before birth and accumulating over the life course.

Researchers are now leveraging the idea of the “exposome”—the sum of environmental exposures an individual experiences across their lifetime—to offer a more holistic lens to brain health. For example, Legaz and colleagues (2025) propose an exposome framework that combines both social factors (e.g., education quality) and physical factors (e.g., air pollution) and connects them to brain outcomes measured with tools such as MRI (as shown by Canning et al., 2025). Legaz and colleagues’ framework highlights how systemic inequities—structures that promulgate an unequal distribution of resources and opportunities in communities—shape the pathways of brain aging. For instance, they report that greater structural inequities are associated with adverse brain outcomes, such as lower brain volume and reduced connectivity among different brain regions, and these outcomes have negative impacts on our cognitive abilities. These impacts are magnified in older adults and those living with dementia. We refer the reader to Legaz et al. for a descriptive figure of this model.

The takeaway for an exposome-informed approach for brain health over the life course

Taking an “exposome” approach means putting environmental justice at the center of studying brain health over the life course. Marginalized communities—often low-income or racially maligned—face the highest exposure to environmental risks while having the least resources to cope. As Legaz and colleagues (2025) emphasize, addressing this imbalance is both ethically imperative and essential to people’s health and wellbeing. Solutions include expanding equitable access to restorative green spaces (Besser et al., 2023), enforcing clean air and water quality standards in underserved areas, and investing in community-led initiatives. Implementing such steps would reduce harmful exposures, build community-level resilience, and promote brain health equity for all.

As air pollution, toxic environmental exposures, and climate change converge with a rapid increase in the global population of older adults (GBD Lancet 2022), we are at a critical juncture: such convergence demands a fundamental rethinking of how we understand and protect brain health across the life course.