Research reveals that environmental and pathological factors can accelerate biological aging of the brain

The rate at which the brain ages can vary considerably between individuals, leading to a discrepancy between the brain’s estimated biological age and chronological age (the actual number of years a person has lived).

This gap may be influenced by various factors, including physical (e.g. pollution) and social (e.g. socioeconomic or health inequalities) exposome, particularly in the case of aging and dementia. Until now, it was unclear how these combined factors could accelerate or delay brain aging in different geographic populations.

Today, in a pioneering study published in Natural medicineResearchers from the Global Brain Health Institute at Trinity College Dublin have led a larger team of international colleagues to develop innovative measures of brain ageing using advanced brain clocks based on deep learning of brain networks.

This study involved a diverse dataset of 5,306 participants from 15 countries, including participants from the United States, Latin America (LAC), Europe, and Asia.

Data from Ireland were integrated with data from other EU countries for the study. By analysing functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) data, the researchers quantified the brain age gaps between healthy individuals and those with neurodegenerative diseases such as mild cognitive impairment (MCI), Alzheimer’s disease and frontotemporal lobe degeneration (FTLD).

The study found that populations in countries with the highest levels of inequality tend to have higher brain ages. This effect was observed in a large and geographically diverse sample, including participants from high-income countries and low- and middle-income countries. This accelerated aging was particularly evident in brain regions most vulnerable to aging, particularly those involving fronto-posterior networks.

The study found that structural socioeconomic inequalities, air pollution, and the burden of communicable and noncommunicable diseases were significant predictors of increasing brain age gaps, particularly in the most deprived countries. Participants diagnosed with dementia, particularly Alzheimer’s disease, had the most critical brain age gaps.

The study also found gender differences in brain aging, with women in Latin American and Caribbean countries showing larger brain age gaps, particularly among those with Alzheimer’s disease. These differences are linked to biological sex- and gender-related disparities in health and social conditions. These findings highlight the role of environmental and social exposomes in brain health disparities.

The results of this study have profound implications for neuroscience and brain health, particularly for understanding the interplay between macro factors (exposome) and the mechanisms underlying brain aging in diverse healthy and demented populations.

The study’s approach, which integrates multiple dimensions of diversity into brain health research, offers a new framework for personalized medicine. This framework could be crucial for identifying individuals at risk for neurodegenerative diseases and developing targeted interventions to mitigate these risks.

The study results also highlight the importance of considering the biological integration of environmental and social factors in public health policies. Policymakers can reduce brain age gaps and promote healthier aging in the population by addressing issues such as socioeconomic inequalities and environmental pollution.

Senior and corresponding author Agustin Ibanez is Professor of Brain Health at Trinity’s Global Brain Health Institute (GBHI) and Trinity School of Medicine, and Director of the Latin American Brain Health Institute (BrainLat). He said: “The age of your brain is not just a matter of years, but also of location and lifestyle. The innovative use of computational neuroscience tools on a large and diverse sample has provided valuable insights into how different exposures can induce accelerated or delayed brain ageing, a critical consideration for policy makers.”