Exercise regularly. Eat well. Sleep enough. Do not smoke. Control your blood pressure.
These are important strategies for protecting health as we age.
But they can create the impression that how we age depends almost entirely on the choices we make ourselves.
Research on brain aging suggests that the picture is more complex.
A large study involving 18,701 people from 34 countries found that the physical and social conditions surrounding people were strongly associated with how their brains appeared to age.
Lifestyle Matters — But It Is Not the Whole Story
Many established risk factors for poor brain health are related to individual behavior and health.
Physical inactivity, smoking, high blood pressure, diabetes and poor sleep can all matter.
But nobody ages in isolation.
Throughout life, we are also exposed to the environment around us.
These exposures may include physical conditions as well as broader social, economic and political circumstances.
Together, this collection of exposures is known as the exposome.
Why Look at Many Exposures Together?
One of the most important findings from the international study was not about one particular environmental factor.
It was about their combined effect.
Researchers examined 73 physical and social factors.
When they considered multiple exposures together, they explained substantially more variation in brain aging than when individual exposures were considered separately.
This makes biological sense.
A person does not experience one risk factor at a time.
Different influences can accumulate and interact over decades.
The Physical and Social Environment May Affect the Brain Differently
The researchers also found that different types of environment were associated with different aspects of brain aging.
The physical environment was more strongly associated with changes in brain structure.
The social environment was more strongly associated with differences in how brain regions communicate with each other.
This suggests that the environment surrounding us may be connected to brain aging through several different pathways.
Does Environment Matter More Than Lifestyle?
That is not what the study shows.
It would be a mistake to interpret these findings as a reason to pay less attention to exercise, nutrition, sleep or cardiovascular health.
These remain important components of prevention.
Instead, the research adds another layer.
Individual lifestyle and the wider environment may both contribute to the conditions in which aging occurs.
They should not be viewed as competing explanations.
Can We Control How Our Brain Ages?
We can influence some factors more easily than others.
We can choose to exercise. We can improve our diet. We can stop smoking and treat high blood pressure.
Changing air quality, socioeconomic conditions or wider social circumstances may be much more difficult for an individual.
This distinction matters because longevity should not be reduced to personal responsibility alone.
Some influences on health exist beyond individual control.
What Does This Mean for Longevity Medicine?
The goal of longevity medicine is not simply to identify one intervention that slows aging.
It is to understand the different factors that influence long-term health and function.
That includes biology, disease risk, lifestyle and potentially the physical and social environment.
The 34-country study does not prove that changing environmental conditions will slow brain aging. It was observational, so it identifies associations rather than direct cause and effect.
But it provides strong evidence that the wider environment deserves a place in how we think about healthy aging.
The future of prevention may therefore require both approaches: helping individuals reduce their personal risk while also understanding the environments in which those risks develop.
