January 01, 2025
We celebrate getting older on the same day each year, but parts of our bodies can actually age at different speeds. A new study points to some of the lifestyle choices that influence the rate of aging in our brains.
Led by researchers from the Karolinska Institute and the University of Gothenburg in Sweden, an international team looked at various biological signals to estimate brain age in 70-year-olds with no cognitive impairment.
What stood out from their analysis of 739 people was the importance of vascular (blood vessel) health when it comes to keeping brains looking young. Habits such as regular physical activity, sticking to a healthy diet, cutting out smoking, and managing glucose levels can improve vascular health.
"A take-home from the study is that factors that adversely affect the blood vessels can also be related to older-looking brains, which shows how important it is to keep your blood vessels healthy to protect your brain," says neurobiologist Anna Marseglia, from the Karolinska Institute.
Older-looking brains were linked to physical inactivity, having diabetes, and having had a stroke, as well as higher levels of inflammation and higher levels of blood glucose – indicating a mix of interconnected factors having an impact.
There were some variations between men and women – with glucose levels making more of a difference to brain age in men, for example – which is something the researchers are keen to follow up on in the future.
The team used a deep learning AI model to assess brain age from magnetic resonance imaging (MRI) scans, having previously trained it on more than 18,000 scans of people without any cognitive issues.
Information from blood samples was then cross-referenced with the assessed brain ages, together with data collected by the researchers on various lifestyle factors, medical conditions, and cognitive tests.
"The algorithm is both accurate and robust, yet easy to use," says clinical geriatrician Eric Westman, from the Karolinska Institute.
"It's a research tool that still needs further evaluation, but our aim is for it also to be of clinical use in the future, such as in dementia investigations."
That link to dementia is an important one: older brains tend to be more at risk of developing dementia conditions such as Alzheimer's disease, and the findings suggest ways of protecting against that cognitive decline.
Previous research has tied brain age to numerous factors – including blood sugar levels, as found in this study, and living in poverty – and many of them we can do something about, either on an individual or societal level. Ultimately, researchers are looking for ways we can stop dementia from developing in the first place.
"Despite the recent introduction of new Alzheimer's drugs, they will not work for everyone with dementia, so we want to study what can boost the brain's resilience against pathological aging processes," says Marseglia.
As women and men appear to have different factors that relate to brain aging, the team now plans to investigate how we develop resilience with a closer look at biological determinants (such as hormones) and sociocultural factors.
"Next year, we'll launch a study to understand how social health – including social engagement, connectedness, and support – in middle and older age, along with sleep and stress, influence brain resilience, with a focus on women's health factors," Marseglia says.
The research has been published in Alzheimer's & Dementia: The Journal of the Alzheimer's Association.
