A new genetic test which calculates the age that a person is likely to develop Alzheimer’s disease, has been developed by scientists.
The technique involves checking for mutations in 26 genes which were found in tens of thousands of dementia patients and which can be used to calculate an individual ‘hazard score.’
Previous genetic testing for Alzheimer’s has largely relied on looking for defects in the APOE gene, which is known to raise the risk of disease 15 fold.
Preventing the development of dementia symptoms is the holy grail of Alzheimer’s research but to succeed we first need accurate methods to predict who is most likely to develop the condition.Dr James Pickett, Head of Research, Alzheimer’s Society,
But even in people without the APOE mutation those with the highest scores could expect to develop Alzheimer’s disease by 84 years old, 10 years earlier than those who tested low on the scale.
"From a clinical perspective, the provides a novel way not just to assess an individual’s lifetime risk of developing Alzheimer’s disease, but also to predict the age of disease onset," said senior author Dr Anders Dale, of the University of California San Diego School of Medicine.
"Equally important, testing of Alzheimer’s genetic risk can better inform prevention and therapeutic trials and be useful in determining which individuals are most likely to respond to therapy."
Around 500,000 people in Britain are living with Alzheimer’s disease and there is currently no treatment for the condition.
Experts believe that when drugs are eventually found, they will need to be given early before the disease has progressed as there is little chance that the brain damage can be reversed and memories brought back once they have gone.
So developing a test that can give an individual’s risk of dementia will help doctors target the right patients, who could also be encouraged to improve their lifestyles to cut their chance of developing disease.
The test, which could use DNA from blood or saliva, was developed using genetic information from more than 70,000 patients with Alzheimer’s disease.
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Dr Rosa Sancho, Head of Research at Alzheimer’s Research UK, said: “Being able to detect who is at an increased risk of developing Alzheimer’s could revolutionise the way we evaluate potential new drugs.
“While these genetic risk scores hold promise as valuable research tools, they will need to be thoroughly evaluated, tested and refined before they could ever be used to help doctors diagnose or treat the disease.
“This study does not suggest that having a high polygenic hazard score means you will definitely develop Alzheimer’s, nor does a low score mean you are immune from the disease. Genetics is only part of the story.”
Dr James Pickett, Head of Research, Alzheimer’s Society, added: "Preventing the development of dementia symptoms is the holy grail of Alzheimer’s research but to succeed we first need accurate methods to predict who is most likely to develop the condition.
"This study’s approach was fairly successful at predicting the likelihood of someone developing dementia over the coming year, but needs to be tested further in mixed, non US populations.
"This genetic risk score could help identify people to take part in research studies, but is not opening a door to genetic testing for dementia risk in the clinic.
"For anyone concerned about dementia the first step is to visit your GP. If you’re looking for ways to reduce your risk, remember what’s good for your heart is good for your head, and it may be possible to lower your risk by staying active, eating well, and learning new skills.”
The research was published in the journal PLOS Medicine.