Social inequality and weak democratic institutions are linked to faster ageing, as are other environmental features such as high levels of air pollution, finds a study spanning four continents¹. Education was one of the top factors that protected against faster ageing.

The study also showed that ageing is accelerated by less-surprising factors such as high blood pressure and heart disease. But the link to social and political influences could help to explain why rates of ageing vary from country to country, the authors say.

How quickly are you ageing? What molecular ‘clocks’ can tell you about your health

“It’s a very important study”, says Claudia Kimie Suemoto, a geriatrician at the University of São Paulo in Brazil who was not involved in the work. “It gives us the global perspective of how these dependent factors shape ageing in different regions of the world.”

Political polarization and uncertainty mean that “we are living in a world of despair”, and that ages people, says lead author Agustín Ibañez, who directs the Latin American Brain Health Institute in Santiago. “We don’t think about the health impacts that this is going to have in the long run.”

The study was published today in Nature Medicine.

Age gaps

The study included 161,981 participants from 40 countries: 7 in Latin America, 27 in Europe, 4 in Asia and 2 in Africa. Just the process of harmonizing these data sets — such as checking that variables were measured in similar ways in different countries — took about 3 years, says Ibañez.

The researchers examined previous research to identify possible factors that hasten or slow ageing and that could be compared across countries. They fed data of these factors into a machine-learning model that predicts a person’s chronological age. That allowed them to calculate each person’s ‘biobehavioural age gap’: the difference between their true chronological age and their age as predicted by the model.

For example, if you are 50 years old but the model predicts that you are 60 years old, you have a biobehavioural age gap of 10 years.

Schooling protects

The top medical risk factors for faster ageing were high blood pressure, hearing impairment and heart disease. Other risk factors included unhealthy weight, alcohol consumption, sleep problems, diabetes and impaired vision.

The factors that provide the best protection against speedy ageing were education, ability to perform activities of daily living and sound cognitive abilities. Other protective factors included physical activity, good memory and the ability to walk well.

Air pollution and brain damage: what the science says

Egypt and South Africa had the fastest ageing, whereas European countries showed the slowest ageing, and nations in Asia and Latin America were in the middle.