Blood Test Estimates How Quickly People Age and Could Predict Alzheimer’s Risk
Scientists have developed a blood test which estimates how quickly a person is ageing. They believe it could be used to identify those who are most at risk of developing Alzheimer’s disease.
The test works out a person’s ‘biological age’ by measuring the vitality of certain genes, and this may be younger or older than the person’s actual chronological age. Those who are older biologically than they are in years are considered to be more likely to develop Alzheimer’s.
Researchers from King’s College London, the Karolinska Institute in Sweden and Duke University in the US looked at levels of RNA – a close cousin of DNA – in the blood of healthy 65-year-olds. By analysing thousands of blood, brain and muscle samples, they worked out the optimum RNA make-up, or ‘signature’, for a 65-year-old.
They found that by identifying how 150 genes differed from this ideal signature they could work out how slowly or quickly a person’s body was ageing. They then produced an ageing score based on these markers, where a high score indicated healthy ageing and a low score meant a person was biologically older than they were in years.
The test was then was used to assess the biological ages of 700 apparently healthy 70-year-old volunteers. Their biological ages differed by more than 20 years, ranging from under 60 to over 80. Those with lower biological ages had better cognitive ability and kidney function, while those with higher biological ages were more likely to have Alzheimer’s disease. Interestingly, the results were shown to be independent of a person’s lifestyle, meaning that common diseases such as heart disease and diabetes would not skew the scores.
An important finding was that the analysed gene activity was the same in the brain and the blood for people with Alzheimer’s disease, giving scientists a way of quickly and easily diagnosing what is happening in the brain just by looking at a blood sample.
“Our discovery provides the first robust molecular ‘signature’ of biological age in humans and should be able to transform the way that age is used to make medical decisions,” says study leader Professor James Timmons of King’s College London. “This includes identifying those more likely to be at risk of Alzheimer’s, as catching those at early risk is key to evaluating potential treatments.”
He adds that identifying those most at risk means that middle-aged people with no dementia symptoms could be put on clinical trials for preventative treatments.
Dr Eric Karran of Alzheimer’s Research UK says: “One of the biggest questions in human biology is how we age, and how this process impacts our wider health and risk for conditions like Alzheimer’s. This study suggests a way to measure a person’s ‘biological age’, and could reveal insights into the ageing process and why some people are more susceptible to age-related health conditions.”