The rate at which the brain ages can vary markedly among individuals, leading to a disparity between the estimated biological age of the brain and the chronological age, which is the actual number of years a person has lived.
This disparity may be influenced by a range of factors, including physical (e.g., pollution) and social (e.g., socioeconomic or health inequalities) exposomes, particularly in the context of aging and dementia.
In a pioneering study, published in Nature Medicine, researchers have developed innovative metrics for assessing brain aging using advanced brain clocks based on deep learning of brain networks.
This study analyzed a diverse dataset comprising 5,306 participants from 15 countries, including those from the United States, Latin America, Europe, and Asia. By examining functional magnetic resonance imaging (fMRI) and electroencephalography (EEG) data, the researchers were able to quantify brain age gaps in both healthy individuals and those with neurodegenerative conditions, such as mild cognitive impairment, Alzheimer’s disease, and frontotemporal lobe degeneration.
The study found that populations from countries with greater socioeconomic inequalities generally exhibited older brain ages. This pattern was observed in a large, geographically diverse sample, encompassing participants from high-income as well as low- and middle-income countries. The accelerated brain aging was particularly pronounced in regions of the brain most vulnerable to aging, notably those involving frontoposterior networks.
Furthermore, the study identified structural socioeconomic inequality, air pollution, and the burden of communicable and non-communicable diseases as significant predictors of increased brain age gaps, especially in more disadvantaged countries. Participants diagnosed with dementia, particularly Alzheimer’s disease, displayed the most pronounced brain age gaps.
The findings of this study have far-reaching implications for neuroscience and brain health, particularly in understanding the interaction between macro factors (exposome) and the mechanisms underlying brain aging across diverse populations in both healthy aging and dementia.
The study’s approach, which integrates multiple dimensions of diversity into brain health research, offers a novel framework for personalized medicine. Moreover, the study’s results emphasize the importance of accounting for the biological embedding of environmental and social factors in public health policies. By addressing issues such as socioeconomic inequality and environmental pollution, policymakers can help reduce brain age gaps and promote healthier aging across populations.
S Moguilner et al. Brain clocks capture diversity and disparities in aging and dementia across geographically diverse populations. Nature Medicine (2024). https://doi.org/10.1038/s41591-024-03209-x
