Blood test could predict risk of potentially fatal strokes, study finds

MRI scans have been the only reliable predictor of strokes in the past – Andrew Brookes

A simple blood test could determine the risk of a potentially fatal stroke, according to a new study.

It would allow doctors to understand whether a person may be at higher risk of a stroke or cognitive decline during their lifetime, say scientists.

Their findings show that measuring concentrations of a network of inflammatory molecules in the blood could allow medics to calculate a risk score for susceptibility for cerebral small vessel disease – a common cause of stroke and a contributor to memory issues, especially in the elderly.

Currently, the only way to determine a person’s risk for cerebral vascular diseases has been to use a combination of imaging such as an MRI scan, family history, demographic variables and other risk factor evaluations.

Study lead author Dr Jason Hinman of University of California, Los Angeles, (UCLA) said that, in clinical practice, neurologists may only find a patient is at risk after they have already had a stroke or other medical event that warns of one.

The new study, published in the journal Stroke, found that by measuring the concentrations of the network of inflammatory molecules in the blood of patients doctors may be able to accurately assess a person’s risk for cerebral small vessel disease and future stroke.

Future risk

Dr Hinman said: “The same way one uses cholesterol tests to evaluate one’s future risk for heart attack, we don’t have such a thing to estimate future risk for stroke.

“I believe we can do that by something as simple as a blood test which in theory can enable broader access to the best level of care and not lock it behind advanced imaging studies and specialist evaluations.”

The research team focused on a biologically-connected network of inflammatory molecules known as the interleukin-18, or IL-18, network, which includes proteins and signalling molecules used to fight several infections.

Previous studies have linked individual molecules in the IL-18 network to cerebral small vessel disease and stroke risk.

But Dr Hinman explained that the concentration of the individual molecules can “fluctuate” in response to other ailments such as the flu or autoimmune disorders, making them unreliable predictors of stroke risk at an individual level.

In 2020, University of California researchers including Dr Hinman found that six molecules in the IL-18 network were associated with the presence of vascular brain injuries during MRI scans.

Building on those findings, Dr Hinman sought to determine whether IL-18 network could be used to assess a person’s susceptibility to a stroke or cognitive decline.

The research team used health data from the Framingham Heart Study which has tracked the medical history of thousands of residents in the city of Framingham, Massachusetts, throughout their lives since 1948.

Blood samples taken from participants had been tested for five of the six molecules later identified as being in the IL-18 network.

Mathematical model

By using the blood samples and medical histories of the Framingham participants, Dr Hinman and his team were able to create a mathematical model that generates a risk score based on the concentrations of the IL-18 network molecules.

Of more than 2,200 Framingham residents included in Dr Hinman’s study, those whose risk scores were in the top 25 per cent had an 84 per cent chance of having a stroke during their lifetime.

Overall, elevated risk scores were associated with a 51 per cent increased risk of stroke.

Dr Hinman says that what remains unclear and requires further study is how or if a person’s risk score can be modified or reduced.

He added: “The real challenge is in the primary care space. Are you at risk before you have an event? That’s what we’re all interested in doing is preventing a stroke before it even happens.”

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