Researchers from Trinity College Dublin have collaborated with international partners to investigate whether social inequality affects our brains. Their research paper was published in Nature aging Today, [Friday, December 27th] by an international team of researchers from the Multipartner Consortium to Expand Dementia Research in Latin America (ReDLat), the Latin American Brain Health Institute (BrainLat), the GIobal Brain Health Institute (GBHI) at Trinity College Dublin and other centers across the whole world. The study reveals a direct link between structural inequality – such as socio-economic differences measured by a country-level index (GINI) – and changes in brain structure and connectivity associated with aging and dementia.
The study also sheds light on how social inequality becomes biologically embedded, especially in underrepresented populations in Latin America and the United States.
Key findings
1. Researchers found that higher levels of disparity are associated with reduced brain volume and disrupted connectivity, especially in the temporo-posterior and cerebellar areas that are essential for memory and cognitive function. These effects were more pronounced in Latin America, underscoring the unique vulnerability of the Latin American population to macro-level socio-economic stressors.
2. The findings also showed that Latinos with Alzheimer’s disease experience the most severe outcomes, suggesting that environmental demands related to structural inequality may worsen neurodegeneration in an aging population. In contrast, the milder effects observed in frontotemporal lobar degeneration support the hypothesis of a more significant genetic influence in this condition. Decreased brain volume and connectivity are commonly observed in patients with dementia and are associated with disease progression and severity.
3. Strikingly, the associations persisted even after individual factors such as education, age, gender and cognitive ability were taken into account, underscoring the independent role of macro-level factors in shaping brain health. Living in a context of total inequality impacts brain health regardless of your specific socioeconomic level, demonstrating the far-reaching effects of societal disparities on the brain.
First author Agustina Legaz, PhD from the ReDLat consortium, said:
“Our findings highlight the urgency of integrating not only individual social determinants of health into global brain health research, but also macro-level exposome factors such as social and physical variables. These findings pave the way for future studies examining the biological mechanisms linking aggregate inequality. to aging and neurodegeneration.”
Dr. Agustín Ibáñez, PhD, professor of global brain health at Trinity College, and director of BrainLat and corresponding author, added:
“This research highlights the critical role of structural inequality in shaping brain health. Given that dementia rates are rising particularly in low- and middle-income countries, our findings highlight the need for targeted interventions to address the root causes of brain health disparities, which appear to exist specific to each region.”
The study advocates a multi-level approach to brain health equity, examining the biological embeddedness of other macro-level exposome factors beyond socioeconomic inequality. These can include variables such as democratic governance, air pollution, migration, climate change and access to green spaces. Identifying and targeting these region-specific modulators could lead to targeted interventions that combat accelerated brain aging and reduce the dementia burden in underserved communities.
Source:
Magazine reference:
Legaz, A., et al. (2024). Structural inequality linked to brain volume and network dynamics in aging and dementia across America. Nature aging. doi.org/10.1038/s43587-024-00781-2.