The place where we live and the politics of the society we live in substantially affect how fast our brains age, according to a Trinity College Dublin scientist.
It follows a study of 161,000 people across 40 countries, co-led by Agustin Ibanez, who is a professor in global brain health at TCD.
“Exposure to toxic air, political instability and, inequality of course affect society, but also shape our health,” Professor Ibanez said of the international study reported today in Nature Medicine.
This is the first major study to reveal that as well as physical effects such as pollution, the politics of where were live – social inequality and weak democratic institutions – speed up brain ageing.
“We need to stop thinking of brain health as a purely individual responsibility,” Prof Ibanez said.
“In our study, we measured the bio-behavioural age gap (BBAG) which represents the difference between a person’s chronological age and the age predicted from a broad range of health, cognitive, social and functional factors.
“A positive BBAG means someone is biologically older than expected, suggesting accelerated ageing. A negative BBAG means they’re ageing more slowly than expected, possibly showing resilience.
“So, yes, some people can have a brain age much younger than their chronological age, while others may have brains that appear older than their years.”
The idea that simply eating well, sleeping right, exercising and being socially active in the community are enough, on their own, to maintain healthy brain ageing, is no longer scientifically valid.
The findings come as democracy is in retreat in many countries, air pollution is reaching crisis levels, and wealth gaps are widening.
The researchers introduced a new way of scientifically measuring exposure to factors that age our brains, and called it the exposome.
The study scientists in Latin America, Africa, Europe, Asia and North America, used AI and epidemiology – the science of how often diseases occur – to determine the local exposome using environmental, social and political factors.
“The results show that where you live, your exposome, can age you several years faster, increasing the risk for cognitive and functional decline,” Prof Ibanez said.
The study found that exposure to social factors like economic inequality, gender inequality, migration, lack of political representation, restricted voting rights and unfair elections negatively impacted brain ageing.
Urban areas like Dublin have episodic spikes
The population in Ireland benefits from several factors that can protect individuals from accelerated brain ageing, according to Prof Ibanez.
These include high education levels, good access to healthcare, relatively stable democratic institutions and lower levels of extreme air pollution compared to other regions.
However, he said there were challenges Ireland needed to address. “While air pollution levels are moderate overall, urban areas like Dublin have episodic spikes, which could have localised impacts,” he said.
“Also, socioeconomic disparities do exist within the country, particularly affecting access to health services.”
The scientists want governments worldwide to protect brain health by reducing air pollution, improving access to education, tackling social inequalities and strengthening democratic institutions.
“If public health authorities act on these insights, we could see healthier ageing, lower dementia rates, reduced healthcare costs and improved societal productivity and well-being,” Prof Ibanez said.
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