Researchers at Trinity College Dublin have engaged in a groundbreaking collaborative effort with global partners to investigate whether societal inequality impacts brain health. Their findings are detailed in a research paper published in Nature Aging today, Friday, December 27th. The study was conducted by an international team from the Multipartner Consortium to expand dementia research in Latin America (ReDLat), the Latin American Brain Health Institute (BrainLat), the Global Brain Health Institute (GBHI) at Trinity College Dublin, and other centres worldwide. It establishes a clear correlation between structural inequalities, such as socioeconomic disparities measured by the country-level GINI index, and alterations in brain structure and connectivity typical of ageing and dementia.
The research particularly highlights how societal inequities are biologically embedded, mainly affecting underrepresented groups in Latin America and the United States. The study presents several critical findings:
Firstly, the researchers observed that greater levels of inequality correlate with diminished brain volume and disrupted connectivity, particularly affecting the temporal-posterior and cerebellar regions crucial for memory and cognitive functions. These impacts were notably more severe in Latin America, underscoring the particular susceptibility of these populations to broad socioeconomic stressors.
Secondly, the study disclosed that Latinos suffering from Alzheimer’s disease endure the most drastic effects. This suggests that the environmental pressures associated with structural inequality might intensify neurodegeneration in ageing populations. In contrast, the milder impacts noticed in cases of frontotemporal lobar degeneration suggest a more substantial genetic influence in this condition. It is important to note that reduced brain volume and connectivity, standard in dementia patients, are linked with the progression and severity of the disease.
Furthermore, the research established that these associations persisted even after accounting for individual factors such as education, age, sex, and cognitive ability. This underscores the independent influence of macro-level factors on brain health, demonstrating that living in an environment of widespread inequality impacts brain health irrespective of one’s specific socioeconomic status. Thus, the research reveals the extensive effects of societal disparities on brain function.
Dr Agustina Legaz, PhD from the ReDLat consortium and the study’s first author, emphasised the critical need to incorporate both individual social determinants of health and broader exposome factors, like social and physical variables, into global brain health research. She highlighted that these findings pave the way for future studies exploring the biological mechanisms linking aggregate inequality to ageing and neurodegeneration.
Dr Agustín Ibáñez, a professor in global brain health at Trinity College and director of BrainLat, also the corresponding author, remarked on the significant role of structural inequality in shaping brain health. He pointed out that with dementia rates rising, particularly in low- and middle-income countries, the study’s findings stress the need for targeted interventions to address the root causes of brain health disparities, which are specific to each region.
The study advocates for a multi-level approach to achieving brain health equity, which involves exploring the biological embedding of other macro-level exposome factors beyond socioeconomic inequality. These could include democratic governance, air pollution, migration, climate change, and access to green spaces. By identifying and addressing these region-specific modulators, targeted interventions could be developed to slow down brain ageing and reduce the burden of dementia in disadvantaged communities.
More information: Agustina Legaz et al, Structural inequality linked to brain volume and network dynamics in aging and dementia across the Americas, Nature Aging. DOI: 10.1038/s43587-024-00781-2
Journal information: Nature Aging Provided by Trinity College Dublin
