Blood test has a 90 percent accuracy rate in determining whether memory loss is due to Alzheimer’s: Study

(The Hill) - A blood test can determine whether memory loss is caused by Alzheimer’s disease with more than 90 percent accuracy, according to a new study published Sunday.

A group of researchers at Lund University in Sweden found that a cutting-edge blood test can significantly outperform diagnoses from both primary care and specialist doctors.

The study, published in the Journal of the American Medical Association, found that a p-tau217 blood test can determine whether memory loss is caused by Alzheimer’s about 91 percent of the time, compared to 73 percent accuracy for specialists and 61 percent for primary care doctors.

While there are gold-standard methods for detecting Alzheimer’s disease available, the current methods are expensive, hard to access and often have long waits. Researchers hope this new method could streamline Alzheimer’s diagnoses and accelerate treatment.

“Importantly, even in places with limited access to these new therapies, an accurate, biomarker-verified Alzheimer disease diagnosis can have a positive effect on clinical care and prognostication,” the study reads.

The p-tau217 test measures the levels of a specific blood peptide that is known as a marker of neurological damage due to Alzheimer’s. By determining the specific levels for tests, doctors could use it to see if cognitive decline is due to Alzheimer’s or another form of dementia.

Tau protein tangles track the buildup of amyloid in the brain, a key sign of Alzheimer's. It can be present decades before serious memory loss kicks in, and is the target of the latest medications fighting the disease. 

Researchers tested about 1,200 people with an average age of 74 who were undergoing evaluations for potential Alzheimer’s, comparing the results of the blood test to doctor diagnoses and full-accuracy spinal tap tests.

Despite the high accuracy of the blood tests, the tests are not surefire, though researchers hope the method can reduce strain on specialist care and make access easier for those who need it.

A similar January study of p-tau217 blood tests found even better diagnosis accuracy of 96 percent.

According to the Mayo Clinic, brain imaging, such as MRI scans, CT scans or PET imaging, are often used to help diagnose Alzheimer’s disease in patients. The Mayo Clinic noted that laboratory blood tests can sometimes be used to detect amyloid and tau levels, but that the tests “aren’t widely available and coverage may be limited.”

The Centers for Disease Control and Prevention (CDC) says Alzheimer’s is the most common form of dementia. The agency defines it as a “progressive disease beginning with mild memory loss and possibly leading to loss of the ability to carry on a conversation and respond to the environment.”

In 2020, the CDC said up to 5.8 million Americans were living with Alzheimer’s.