The abundance of 13 proteins in your blood seems to be a strong indicator of how rapidly your brain is ageing. This suggests that blood tests could one day help people track and even boost their brain health.

Most previous studies that have looked at protein markers of brain ageing in the blood have involved fewer than 1000 people, says Nicholas Seyfried at Emory University in Atlanta, Georgia, who wasn’t involved in the new research.

To get a broader idea of the impact of these proteins, Wei-Shi Liu at Fudan University in China and his colleagues analysed MRI brain scan data from nearly 11,000 adults from the UK Biobank project, whose ages ranged from around 50 to 80 at the time of imaging.

Using data from 70 per cent of the participants, Liu’s team trained an artificial intelligence model to predict how old the participants were based on features of the brain images, such as the size of different brain regions and how distinct parts connected to each other. When the model was applied to the remaining 30 per cent of participants, its predictions were accurate to within 2.7 years of their actual ages.

Next, the researchers used the model to predict the age of a separate group of nearly 4700 people, aged 63 on average, who also had their brains imaged for the UK Biobank. The team calculated the difference between these participants’ actual ages and the ones predicted by AI, called the brain age gap. “The higher the AI-predicted age is relative to their actual age, the faster their brain is ageing,” says Liu.

This group also gave blood samples at around the same time that their brains were imaged. From this, the team pinpointed eight proteins that seemed to strongly increase, and five that became less abundant, with a larger brain age gap.

In an analysis of data from previous studies, the researchers confirmed that the proteins are produced by brain cells and that their levels may influence the risk of dementia and stroke.

This suggests that blood tests for these proteins could indicate how quickly someone’s brain is ageing. “These markers could be the canary in the coal mine to tell you, ‘hey, look, let’s start intervening to slow your brain ageing now while you’ve got enough time’,” says Seyfried.

But for this to be useful, we need to know that these proteins can be altered by lifestyle changes. “You want to be able to say, ‘if you run this much, you lose this much weight, you change your diet, [then] you can modify those levels to bring them back into the normal range’,” says Seyfried.

The research was mostly carried out on white, wealthy people, so further research is needed to see whether the results apply to other populations of more diverse ethnicities and income levels, says Seyfried.

The team now hopes to carry out research in animals to pinpoint how the 13 proteins affect the brain. For instance, the researchers may test whether disrupting levels of these proteins affects cognition or even the development of neurodegenerative conditions, says Liu. “In the next couple decades, this could open up ways to target the proteins to slow ageing and disease.”

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