Unpacking the Exposome: How Our Environment Shapes Brain Ageing Across the Globe—and What It Means for the Middle East

As the world grapples with rapidly ageing populations, particularly in low- and middle-income countries, understanding what drives healthy, or unhealthy, ageing has never been more urgent. Recent global research is revealing that ageing is not just about biology or genetics. It is also powerfully shaped by what we are exposed to throughout life: our air, food, stress, relationships, and broader socioeconomic environments. This emerging field of “exposomics” offers a powerful lens to understand how these factors shape brain health and cognitive ageing. In a major new study spanning 40 countries, Egypt and South Africa were the only African nations represented, underscoring both the promise and the gaps in how this science can inform public health across Africa and the Middle East.

Ageing is a complex and ever-changing process, just like human life itself. To truly understand it, we need to move beyond looking for a single cause and instead consider the many different factors that influence how we age. This is where exposomics comes in.

What Is the Exposome and Why Does It Matter?

Exposomics is the study of everything a person is exposed to throughout their life that might affect their health, from the air we breathe and the food we eat, to our lifestyle, stress levels, and even internal processes like inflammation. All of these exposures, both external and internal, are referred to as the exposome. Exposomics examines how these combined influences impact our health over time.

Since these exposures vary by age, location, lifestyle, and life experiences, it’s essential to study ageing across the entire lifespan, a concept known as the life course approach. This helps provide a more comprehensive understanding of how and why we age the way we do.

This approach was central to a recent paper published in Nature Medicine, which compared ageing-related exposures in 40 countries. The study focused on identifying the supports that promote healthy ageing, particularly from the perspective of brain health, which helps us better understand what drives the brain ageing process across different environments and populations.

The Brain Clock: Measuring Cognitive Ageing

It is now accepted that cognitive functions can decline normally with the ageing process; however, the percentage of this decline can vary. The stage of cognitive functions in the brain can be illustrated as a clock, hence the name ‘brain clock’. The point is that sometimes your brain clock could be faster than the normal pace. To understand what can cause an expedited brain clock, or in other words, poorer cognitive function compared to what is expected for one’s age, is a core question for understanding modifiable risk factors for brain diseases and protective factors promoting brain health.

For many years, it was widely believed that biology plays a major role in determining health and disease. This understanding has shaped our healthcare approaches, which aim to identify risk genes, hormones, and biomarkers for specific diseases. While our biology is definitely a strong determinant of health status, including brain health and ageing outcomes, it is not the main player. As our knowledge grew, we learned that exposures could also influence our health status. An additional layer of complexity is the introduction of internal body responses to external exposure, which was originally named the gene–environment interaction but later, due to the introduction of several new actors, was renamed the exposome. 

Nowadays, exposome stands for the totality of exposures across life and its interaction with internal body responses/vulnerability. The one challenge is to define “exposures” as physical environmental exposure, in term of pollutants e.g. pesticides or heavy metals, is the first target for many studies following the conventional model of research.

However, with the inclusion of more disciplines in researching ageing, our definition of exposome began to change, again, following the complex nature of human life. Thus, the term “exposure” extended to encompass other dimensions. The social exposome is a comprehensive examination of social factors and their effects. This plays a major role in shaping health, in general, and brain wellbeing specifically. Economic exposome is another layer to be added to the paradigm of exposure, with the impact it has on equity and equality and their reflection on health and wellbeing. The psychological exposome is another component related to the development of stress and psychological traumas that shape one’s wellbeing.

What Global Research Tells Us About Brain Ageing

One major lesson learned now is that the definition of “exposure” or “environment” extends beyond the conventional view of physical pollutants to encompass everything and every experience that a human being will be exposed to throughout life. This complex model of exposome and its relation to brain health was applied in this work. The challenge was, and will always be, having harmonised data sets that allow for comparability across cohorts and populations. One success of the current research was the ability to connect different cohorts with minimal comparable datasets. The data collected, focusing on brain performance in terms of cognitive functions tools, was correlated with diverse external exposures ranging from air pollution to social unrest, inequity, and even political problems. 

The results showed that social factors can affect brain health, and an expedited brain clock (resulting in poor cognitive function with age) was observed more frequently in populations from Africa compared to those in Europe. Although these results may be predictable, the study was the first to provide scientific evidence of how different external factors can accelerate the brain ageing process, leading to less healthy ageing outcomes.

Africa’s Ageing Alarm: What Egypt’s Data Reveals

The inclusion of Egypt in this landmark study offers rare and crucial insight into how the exposome affects brain ageing in the Middle East and North Africa (MENA) region. Egypt, with its dynamic and complex social, political, and environmental landscape, presents a vital case study for understanding how factors such as air pollution, socioeconomic inequality, and social stressors can interact to influence brain health. Findings that populations in Africa showed faster “brain clocks” and greater cognitive decline compared to their European counterparts raise urgent questions for the region. These insights are particularly important as Middle Eastern populations face their own demographic shifts, with rising life expectancy and growing elderly populations, but often without parallel investments in healthy ageing research and policy infrastructure.

The Role of MENARAH: Building a Healthier Future for Ageing in MENA

The MENARAH (Middle East and North Africa Research on Ageing and Health) Network plays a pivotal role in advancing this field by connecting researchers, policymakers, and practitioners across the region to build a shared evidence base on ageing. In a context where ageing-related data is scarce and often fragmented, MENARAH’s mission becomes even more critical. By promoting interdisciplinary collaboration and region-specific research, MENARAH can help fill the current knowledge gaps—ensuring that future exposomics research more fully represents the diversity of the MENA region. This will ultimately support better health policy, improved equity in ageing outcomes, and more dignified ageing experiences for populations across the Middle East and North Africa.