Diagnosing Alzheimer’s Disease
A definitive diagnosis of Alzheimer’s was once only possible at autopsy, but the development of biological markers – biomarkers – allow the disease to be diagnosed in the living. The markers can be picked out on positron emission tomography (PET) brain scans and through detection in fluid from lumbar puncture (spinal tap) procedures. However, these tests are time consuming and expensive and only help diagnose Alzheimer’s at an advanced stage. New biomarkers are urgently needed to catch Alzheimer’s at its early stages so clinicians can intervene early. Scientists at North Carolina Central University have just found one that could fit the bill.Identifies Patients With Mild Cognitive Impairment
To find a worthy biomarker some scientists have turned to subtle chemical changes in a protein called tau. These changes can make tau more likely to clump and form tangles. This process interferes with the transmission of nerve impulses and leads to the loss of brain cells. Cognitive decline, memory loss and behavior changes follow in due course. Two such modifications are called p-tau181 and p-tau217, which we told you about last year. These biomarkers effectively differentiate people with Alzheimer’s disease from people with other brain diseases—and that’s huge. But still, other biomarkers are needed to spot early changes in cognitive function and give doctors and patients their best chance to slow the disease. The North Carolina researchers looked for additional p-tau biomarkers using brain samples from people who died of both Alzheimer’s and other conditions. The researchers found several of interest, some of which could differentiate Alzheimer’s from the other health problems. But the biomarker that stood out was p-tau198. This biomarker not only replicated what p-tau181 and p-tau217 could do, but more importantly both p-tau198 and p-tau217 could also differentiate brain tissue of patients with mild cognitive impairment (MCI) from older subjects without MCI, a condition that precedes and gives rise to a higher risk of Alzheimer’s.Low-Cost Blood Test in The Pipeline
Professor Bin Xu, who led the team, said Alzheimer's "is a slowly progressive disease, which gives us a long window of opportunities to apply medical intervention if we can detect [Alzheimer's-related] changes early. "Currently, there are no well-established, minimally invasive tests available for early Alzheimer’s diagnosis. Our test, once validated in blood, will have the advantages of low cost and minimal invasiveness.” The brain markers p-tau198 and p-tau217, he continued, “could help clinicians intervene early, as new treatments become available, before significant neurological damage occurs. “We believe our discovery approach may work for finding new protein biomarkers in other aging-related neurodegenerative diseases, such as Parkinson's disease and Lou Gehrig's disease. “Our discovery came from postmortem brain analysis,” Dr. Xu added. “We plan to extend to premortem living patients by sampling their blood, cerebral spinal fluid [or both]. This work is in progress.”