INDIANA – New blood tests could help doctors diagnose Alzheimer’s disease faster and more accurately, researchers reported Sunday – but some appear to work far better than others.
A combined blood test for cognitive decline has a 90% accuracy rate in determining whether memory loss is due to Alzheimer’s disease, a new study found.
One part of the blood test—plasma phosphorylated tau 217, or p-tau217 for short—is one of several blood biomarkers scientists are evaluating for use in the diagnosis of mild cognitive impairment and early-stage Alzheimer’s disease.
The test measures tau protein 217, an excellent indicator of amyloid pathology, said study coauthor Dr. Sebastian Palmqvist, an associate professor and senior consultant neurologist at Lund University in Sweden.
Research found a similar p-tau217 test is up to 96% accurate in identifying elevated levels of beta-amyloid and up to 97% accurate in identifying tau.
Increases in p tau-217 concentrations in the blood are profound in Alzheimer’s disease, which is more than eight times higher compared with elderly without the disease, Plamqvist added.
The peptide p-tau217 is unique in that it can be detected only when amyloid plaques are present in the brain.
The U.S. Food and Drug Administration has not formally approved any of the tests, and there is little insurance coverage.
Don’t expect blood tests for Alzheimer’s to routinely pop up in your primary doctor’s office anytime soon, however. More research is needed to verify the positive results in studies, guidelines for physician use must be established and distributed, and physicians must be educated about any possible nuances. Even specialists can struggle to tell if Alzheimer’s or something else is to blame for a patient’s symptoms.
The tests aren’t yet for people who don’t have symptoms but worry about Alzheimer’s in the family.
New drugs, Leqembi and Kisunla, can modestly slow worsening symptoms by removing gunky amyloid from the brain. But they only work in the earliest stages of Alzheimer’s, and proving patients qualify in time can be difficult. Measuring amyloid in spinal fluid is invasive. A special PET scan to spot plaques is costly; getting an appointment can take months.
In the meantime, research has shown that many actions people can take to prevent or slow cognitive decline include regular exercise, eating a Mediterranean-style diet, and treating vascular risk factors like high blood pressure, high cholesterol, and diabetes.
More than 6 million people in the United States and millions more around the world have Alzheimer’s, the most common form of dementia.
