A landmark international study published today in Nature Medicine redefines healthy ageing as a deeply ecological, social, and political issue, urging public health strategies to move beyond lifestyle-focused approaches. The study, which involved nearly 162,000 participants across 40 countries, found that exposure to air pollution, systemic inequality, and weakened democratic institutions significantly hasten the ageing process. Spearheaded by the Global Brain Health Institute at Trinity College Dublin, the research marks a paradigm shift in understanding the determinants of brain health and ageing.
The study introduces the concept of the global exposome—a comprehensive framework for examining how physical, social, and political environments affect health across the lifespan. Central to this analysis is a novel metric called the biobehavioural age gap (BBAG), which captures the difference between a person’s actual age and the age predicted from various indicators such as cognitive performance, functional ability, education, and cardiometabolic health. A greater gap indicates accelerated ageing, often driven by unfavourable conditions. The research demonstrates that this gap is not random but instead follows discernible patterns that reflect regional inequalities and governance quality.
Utilising advanced AI and epidemiological modelling, the multinational research team uncovered stark differences in ageing outcomes based on environmental and societal exposures. For instance, participants from regions such as Egypt and South Africa exhibited some of the highest BBAG scores, indicating faster ageing. In contrast, parts of Europe—especially those with higher national income and stronger democratic institutions—showed slower biological ageing. These disparities were linked not just to physical exposures like toxic air but also to structural inequities such as gender disparity, economic inequality, migration pressure, and political exclusion.
Dr. Agustin Ibanez, the study’s senior author, emphasised the need to shift from an individualistic view of brain health to a broader, ecological model. “Our biological age mirrors the conditions in which we live. Toxic air, social inequity, and unstable governance don’t just shape societies—they biologically shape individuals,” he stated. His call for a “neurosyndemic” framework highlights the intersecting crises that exacerbate health decline, particularly in under-resourced and politically fragile settings. This shift is especially critical as the world faces compounding crises: rising authoritarianism, environmental degradation, and widening social divides.
The study’s implications are far-reaching. The BBAG not only predicted current health status but also forecasted future declines in cognition and functionality, suggesting its utility in preventive health strategies. These measurable age gaps serve as a biological fingerprint of one’s exposome and could help tailor interventions at both national and local levels. For instance, people living in countries with restricted political freedoms, limited voting rights, and unfair elections were biologically older than their peers in more democratic settings, even when their chronological ages were the same. This demonstrates that structural governance failures are not abstract concepts but have tangible effects on public health and ageing trajectories.
Sandra Baez, co-author and Atlantic Fellow at GBHI, emphasised that “healthy ageing is not simply the outcome of good genes or healthy habits—it is profoundly shaped by the policies, inequalities, and environmental exposures around us.” In light of these findings, the authors argue for a bold, upstream shift in public health policy. Rather than focusing solely on diet, exercise, or smoking cessation, efforts to promote healthy ageing must confront structural inequalities and governance deficits head-on. This includes curbing air pollution, ensuring equitable access to education and healthcare, and strengthening democratic institutions. Only then can ageing be decelerated globally and dementia risk meaningfully reduced.
More information: Agustin Ibanez et al, The exposome of healthy and accelerated aging across 40 countries, Nature Medicine. DOI: 10.1038/s41591-025-03808-2
Journal information: Nature Medicine Provided by Trinity College Dublin
