A developed by neuroscientists at the University of Pittsburgh can detect signs of Alzheimer鈥檚 disease in a blood sample more accurately than previous tests, by spotting an elusive sign of the disease.
The test works by detecting a novel biomarker of Alzheimer's called brain-derived tau, according to a study by the team published in the medical journal Brain on Monday.
is a protein that supports neurons, or nerve cells, in the brain. The abnormal accumulation of tau, especially in tangles of the protein, is a hallmark of Alzheimer's disease. While tau is associated mostly with brain cells, cells outside the brain can produce a variation the study calls "big tau."
By figuring out how to detect brain-derived tau in blood, the team has created a method for diagnosing Alzheimer's that is more accessible than existing methods.
鈥淎t present, diagnosing Alzheimer鈥檚 disease requires neuroimaging,鈥� senior author Thomas Karikari said in a issued on Monday. 鈥淭hose tests are expensive and take a long time to schedule, and a lot of patients, even in the U.S., don鈥檛 have access to MRI and PET scanners."
The current framework for detecting Alzheimer's, set by the U.S. National Institute on Aging and the Alzheimer's Association, is called the amyloid, tau and neurodegeneration (ATN) method.
This method requires scientists to detect three components, or biomarkers, of Alzheimer鈥檚 disease 鈥� amyloid plaques, tau tangles and neurodegeneration 鈥� in the brain. It can be achieved either through imaging or by analyzing cerebrospinal fluid samples, but Karikari said these methods are costly and require a lot of resources.
So Karikari's team set out to develop a simple, minimally-invasive and cost-effective blood test that could detect the same biomarkers.
鈥淭he most important utility of blood biomarkers is to make people鈥檚 lives better and to improve clinical confidence and risk prediction in Alzheimer鈥檚 disease diagnosis,鈥� Karikari said.
Up until now, blood diagnostic methods have been able to detect two out of three of the biomarkers needed to diagnose Alzheimer's 鈥� amyloid and a version of tau. However, they've struggled to detect the third component 鈥� neurodegeneration markers specific to Alzheimer鈥檚. So the team developed a technique to distinguish brain-derived tau in blood from free-floating big tau using a special antibody that selectively binds to brain-derived tau.
Karikari and his team hope this new, more accessible blood diagnostic technique can improve clinical trial design and expand trial enrolment to include patients from populations that have historically been overlooked by such trials. To that end, they are planning to conduct large-scale clinical blood screening for brain-derived tau in a wide range of participants from diverse racial and ethnic backgrounds, memory clinics and the community.
鈥淭here is a huge need for diversity in clinical research, not just by skin colour but also by socioeconomic background,鈥� Karikari said.
鈥淭o develop better drugs, trials need to enrol people from varied backgrounds and not just those who live close to academic medical centres. A blood test is cheaper, safer and easier to administer, and it can improve clinical confidence in diagnosing Alzheimer鈥檚 and selecting participants for clinical trial and disease monitoring.鈥�
Correction:
This story has been updated to state that 鈥渂ig tau鈥� is produced outside of the brain.
