The test searches for a protein linked to Alzheimer’s disease (Image: Getty)
A blood test that detects a protein linked to Alzheimer’s disease may predict brain decline a decade before symptoms appear. A study found that healthy older adults with high levels of the protein had a 78% risk of developing cognitive impairment over 10 years. The test could help pave the way for earlier treatment to prevent dementia, according to experts.
Maria Carrillo, chief science officer and medical affairs lead at the Alzheimer’s Association, said: “This is the future of Alzheimer’s care, targeting the earliest stages of the disease, including in its silent stage before memory issues arise. This is when treatments may have the greatest benefit — perhaps even keeping people from ever experiencing dementia symptoms.”
Dr Carrillo said: “Identifying people at risk earlier could fundamentally change how we diagnose, treat and prevent dementia, with far-reaching health, happiness and cost implications for patients, families, healthcare systems and society.”
The US study collected data from almost 2,700 healthy adults with an average age of 70. Patients provided blood samples and were tracked over time, completing memory, thinking and daily functioning tests.
The study found that people with very high levels of p-tau217 — more than twice the average measurement — had a 78% risk of progressing to cognitive impairment within 10 years and a 38% risk within five years.
People with moderately elevated levels had a lower but still significant risk of 15% over five years and 45% over 10 years. The blood tests provided predictive information beyond that gathered from brain scans and genetic testing.
Tangles of tau protein in the brain are a known hallmark of Alzheimer’s disease. Study leader Professor Rachel Buckley, an expert in neurology at Mass General Brigham and Harvard Medical School in Boston, said: “Our findings provide some of the clearest evidence yet that elevated p-tau217 levels may help detect dementia risk years earlier — even in adults with no noticeable memory or thinking problems.
“Once verified, these blood tests could be used to recruit patients for clinical trials of treatments to prevent cognitive decline and dementia.
“In the future, when treatments are approved for use early in the disease process, these tests could help guide monitoring, treatment decisions and counselling for patients and families.”
The researchers noted that p-tau217 alone could not fully predict an individual’s risk and longer-term studies will be needed.
The test could one day help patients access treatment before dementia develops (Image: Getty)
The findings will be presented on Wednesday at the world’s largest annual gathering of dementia scientists — the Alzheimer’s Association International Conference — in London.
A blood test for p-tau217 is also being evaluated in the UK. Researchers at University College London began recruiting patients last August.
Dr Richard Oakley, associate director of research and innovation at Alzheimer’s Society, said blood tests were “the most promising development in dementia diagnosis research”.
He added: “In the future, this tool could support clinicians to identify people at risk and support them to take steps to reduce their risk or even access preclinical treatments as they become available.
“Through the Blood Biomarker Challenge, Alzheimer’s Society — alongside Alzheimer’s Research UK — is helping bring blood tests into the NHS for people who are already experiencing symptoms.
“To keep pace with the tide of innovation in diagnosis and treatment, we also need to see investment in preparing systems for these innovations so that services have the people and tools they need.”
Dr Sara Rodrigues, senior research manager at Alzheimer’s Research UK, said: “At present, blood tests identify changes in pathology associated with Alzheimer’s disease, but they haven’t been validated to predict whether a person will go on to develop the condition.
“It is important to note that in the study nearly a quarter of people with low levels of p-tau217 still went on to experience declines in memory and thinking. This suggests further research is needed to understand how to interpret these results.”
