“Baleáme con tres rosas que duelan a cuenta del hambre que no te entendí, chiquilín"

"[Shoot me thrice with roses that sting serving as a reminder of a hunger I could not fathom, Kiddo]"

(Chiquilin de Bachin, Tango vals, Piazzolla & Ferrer, 1969)

Beyond neuroeconomics: The macroeconomics of brain health

The intersection of neuroscience and economics has traditionally been explored through neuroeconomics, focusing on understanding human decision-making. Neuroeconomics uses tools like functional magnetic resonance imaging (fMRI) and electrophysiology (EEG) to examine how individuals weigh risks, evaluate social rewards, and make choices under uncertainty. Everyday examples include decisions about saving for retirement or choosing healthier diets. These studies have highlighted the complex interplay of emotion and reasoning in economic behaviors.

However, the economy goes far beyond individual human choices and microeconomy, creating long-standing restrictions on our brain's ability to flourish. Similarly, brain health goes far beyond purely cognitive correlates, providing a critical reserve for overall health. A new transdisciplinary framework connecting the brain, body, and environment seems crucial to understanding brain health's embedded and situated nature. 

The social exposome and macroeconomy

Economists, especially health economists, have long studied structural inequalities to understand how socioeconomic disparities impact progress, resilience, and overall health. More recently, combining aggregate-level measures of society (e.g., at the country, state, or city level) with brain health outcomes has revealed unique insights. In brief, the social exposome—the cumulative social exposures individuals face throughout their lives—seems to play a critical role in shaping brain health. Here, we synthesize three recent studies from our group that advance this topic. Structural inequalities, such as unequal income distribution at an aggregate level (measured by the Gini coefficient), affect access to education, healthcare, and nutritious food, all of which are critical for brain health. Over time, these disparities become biologically embedded, influencing brain structure, function, and aging.

In the first study, we analyzed EEG data from over 1,300 participants across nations with varying levels of inequality. Higher societal inequality was linked to reduced neural complexity and increased random neural activity, particularly in temporo-posterior brain regions. These changes were measured with advanced metrics of brain health and showed more significant impact than individual factors such as sex, cognition, or education. In another study, we examined over 2,100 individuals across the Americas. Greater inequality correlated with reduced brain volume and connectivity, especially in regions vulnerable to aging and dementia. The effects were more pronounced in Latin American populations, highlighting significant regional disparities. Socioeconomic inequality also impacted the brain burden of dementia (e.g., Alzheimer's disease and frontotemporal lobe degeneration). The impact of structural inequality persisted even after controlling for individual factors such as education, age, and gender. These two studies expand upon our recent analysis of brain-age gaps in 5,306 participants from 15 countries using deep learning applied to fMRI and EEG data. Latin America and the Caribbean participants exhibited more significant brain-age gaps linked to socioeconomic inequality and other exposome metrics. Brain aging was more pronounced in females, individuals with Alzheimer's disease, and those from the Global South, underscoring the impact of diversity on brain health.

These results illustrate in a very concrete way how simple metrics of aggregate-level socioeconomic inequality can be linked to brain health outcomes, evidencing the profound impact of societal macro-level factors on individual brain health.

The future of transdisciplinary precision brain health

The studies summarized above represent some of the first steps in linking macroeconomics with brain health outcomes. We believe it is time to develop a more interconnected, syndemic and synergic understanding of brain health and disease. Multiple exposomes interact in real life and across the lifespan. However, our science still does not adequately assess these dynamics and their cumulative impacts. This knowledge is critical to understanding brain health in real-world settings and moving beyond our frameworks' current limitations toward a new level of precision.

A key agenda involves linking different levels of exposomes with diverse brain health outcomes. For instance, physical (e.g., air pollution, heatwaves, limited green spaces), social (e.g., structural inequality, gender disparities, education quality, income), and sociopolitical exposomes (e.g., threats to democracy, radicalization, infodemics) need to be systematically incorporated into computational models across different global settings. Similarly, brain health metrics must be assessed across multiple levels, including whole-body health, brain age gaps, genetic predispositions, and inflammation markers, among other measurements.

Such a framework requires more significant efforts in data collection and sharing, as well as geolocalization and transdisciplinary dialogues. While we are far from fully developing such an approach at present, moving in this direction will ensure a more situated, embedded, and precise understanding of brain health. 

In the future, policymakers may use these precision medicine approaches to inform interventions, such as improving access to education, ensuring healthcare equity, strengthening social safety nets, and enhancing environmental quality to mitigate the effects of inequality. Structural socioeconomic inequality is more than just an economic issue; it is a critical determinant of brain health that interacts with multiple macrosocial and individual-level factors. By merging macroeconomics, neuroscience, and social science, we can illuminate how macrosocial factors shape our brain health and capital and propose actionable strategies for building a healthier, more equitable society.

The poster figure was created using GPT4 under the author's supervision.