Researchers have taken a major step toward creating a blood test that can predict dementia risk more than a decade before a patient is officially diagnosed with the disease.
Hopes for the test rose after scientists discovered biological markers for the condition in blood samples taken from more than 50,000 healthy volunteers enrolled in the UK Biobank project.
Analysis of blood has identified patterns in four proteins that predict the development of dementia in general, especially Alzheimer's disease and vascular dementia in older people.
When combined with more traditional risk factors such as age, gender, education, and genetic susceptibility, researchers say this protein profile can detect dementia almost 15 years before it becomes clinically confirmed, with an estimated 90% accuracy. Dementia can now be predicted.
More than 55 million people worldwide have dementia, and this number is expected to reach 78 million by 2030. Approximately 70% of all dementias are caused by Alzheimer's disease, of which 20% is vascular dementia caused by blood vessel damage. .
“We hope to develop this as a screening kit for use in the NHS,” said Professor Jianfeng Feng, who holds posts at the University of Warwick and Fudan University in China.
A series of recent studies have demonstrated the potential of blood tests to flag patients most likely to develop dementia. With this information, doctors can quickly decide which patients should undergo further evaluation, including a complete diagnostic test for Alzheimer's disease.
Early identification of the disease is crucial if patients are to benefit from two new Alzheimer's drugs, lecanemab and donanemab, which are under review by the UK medicines regulator. If approved, the National Institute for Health and Care Excellence will consider the costs and benefits before deciding whether to make it available to the NHS.
The U.S. drug regulator, the Food and Drug Administration, has approved lecanemab and a ruling on donanemab is expected soon. European regulators are still reviewing both drugs.
Since lecanemab, a synthetic antibody therapy developed by US Biogen and Japan's Eisai, made headlines in 2022 for slowing the progression of Alzheimer's disease, doctors and medical charities have warned that health services should offer such a drug. He warned me that I wasn't ready.
Patients receiving lecanemab or donanemab have early-stage Alzheimer's disease and will require a lumbar puncture or PET scan to confirm the presence of amyloid protein in the brain. Toxic amyloid clumps are one of the hallmarks of Alzheimer's disease. However, Alzheimer's Research UK estimates that only 2% of eligible patients undergo such tests.
Research is underway to develop and deploy simple blood tests to diagnose Alzheimer's disease, but even if rapid diagnosis is possible, challenges remain. The new drug must be injected into patients every two weeks, and patients will need regular MRI scans to check for brain swelling or bleeding, as potentially fatal side effects can occur.
In the latest study, blood samples from 52,645 UK adults without dementia were collected between 2006 and 2010, frozen and analyzed 10 to 15 years later. More than 1,400 participants developed dementia.
Researchers used artificial intelligence to examine the association between about 1,500 blood proteins and the onset of dementia years later. Writing in Nature Aging, they explain how four proteins, Gfap, Nefl, Gdf15, and Ltbp2, are present at abnormal levels among people who develop all-cause dementia, Alzheimer's disease, or vascular dementia. It explains what was done.
Elevated protein levels were a warning sign of disease. Inflammation in the brain can cause cells called astrocytes to overproduce Gfap, a known biomarker for Alzheimer's disease. People with elevated Gfap were more than twice as likely to develop dementia than those with lower levels.
Another blood protein, Nefl, is associated with nerve fiber damage, while Gdf15 may be higher than normal after cerebrovascular damage. Scientists found that elevated levels of Gfap and Ltbp2 are more specific to dementia than other brain diseases, and changes occur at least 10 years before a dementia diagnosis.
Researchers are in talks with companies to develop the test, but said costs would need to come down to make it possible to achieve the test, which currently costs several hundred pounds.
Dr Shena Scales, Head of Research at Alzheimer's Research UK, said: 'This new study shows that by looking at the levels of a specific protein in the blood of healthy people, we can detect dementia before symptoms develop. “This adds to the body of evidence that it can be predicted accurately.”
Further research is needed to understand how well such tests work in more diverse populations. Scales added: “Even if a test shows promise in a study like this, it still needs regulatory approval before it can be used in a medical setting.
“Blood tests show great potential, but so far none have been validated for use in the UK. We are proud to be working with the Alzheimer's Society, NIHR and the generosity of People's Postcode Lottery participants. With generous funding, we are funding research to provide the evidence the NHS needs to move forward with blood tests to diagnose Alzheimer's disease.”