June 24, 2025

A blood test that can help detect early signs of Alzheimer’s disease will soon be available for those who meet certain criteria. This first-of-its-kind, simple test will improve chances for early detection and treatment of Alzheimer’s, which affects about 7 million Americans.

Johns Hopkins neurologist Abhay Moghekar, M.D., is one of the researchers who developed the blood test. “In the last few years,” he explains, “several therapies have been developed to ease Alzheimer’s symptoms and slow progression of the disease. These are very helpful, but our ultimate goal is to prevent Alzheimer’s disease, not treat it once you have it. This blood test is an early step in the path to prevention.”

It was developed based on research completed at Johns Hopkins, Lund University in Sweden and private companies.

Moghekar’s lab contributed important data and validated the test against the results from cerebrospinal fluid biomarkers already approved by the FDA. “They pooled subjects from three studies to come up with this test,” he says. “We contributed many of the samples and did the testing of those samples here in our lab.”

Who is eligible for the blood test that helps diagnose Alzheimer’s?

The test was recently approved by the Food and Drug Administration for those who are 55 or older and have been medically assessed as experiencing cognitive decline. A medical assessment includes an evaluation of a patient’s medical history and cognitive tests.

“All of us have forgotten keys or misplaced glasses,” Moghekar says. “But a medical assessment shows if a person has more than normal forgetfulness and if it affects their ability to function.”

How do you get the Alzheimer’s blood test?

For those who meet the qualifications, primary care physicians or specialists can order the blood test. As with other blood tests, the patient goes to a lab for the test. Most labs will draw blood and send it to a centralized lab that has the equipment and necessary kits to perform the measurements.

Is the Alzheimer’s blood test covered by insurance?

While the test is FDA approved, insurance coverage is a work in progress and may be approved in the near future.

What does the blood test show?

The test itself does not diagnose Alzheimer’s disease. It measures two proteins in the blood and calculates a ratio of these proteins to determine if amyloid plaque is present in the brain. Amyloid is a misfolded protein that is an early sign of Alzheimer’s disease.

When the blood is sent to a lab for testing, a range is provided that doctors can then interpret. Patients with scores over the high-end cutoff have more than a 90% likelihood of having Alzheimer’s disease, while patients below the low range almost certainly do not have it.

About 20% of those receiving the blood test will fall in the intermediate category, Moghekar says. They will require additional testing from neurologists or gerontologists before a definitive diagnosis can be reached.

What happens if the blood test indicates Alzheimer’s disease?

Results of the blood test alone do not mean a person has Alzheimer’s. Doctors must consider the blood test results along with other information, including medical history, family history, cognitive testing and medications that may influence the results. They may recommend that a person with high-end results see a neurologist, geriatrician or geriatric psychiatrist to determine if the new Alzheimer’s disease medications are appropriate.  

How reliable is the blood test at predicting Alzheimer’s?

According to the FDA, the new blood test can reliably predict the presence or absence of amyloid plaque associated with Alzheimer’s disease at the time of the test in patients who are cognitively impaired.

What is the benefit of having the blood test for Alzheimer’s?

An earlier diagnosis can lead to earlier treatment of Alzheimer’s. It can also help set a person’s mind at ease if the blood test shows that they don’t have early signs of the disease. And because it’s a simple blood test, it is relatively easy for qualifying patients to receive.

Before the new blood test was developed, amyloid buildup could be detected through PET scans of a patient’s brain, or by analyzing cerebrospinal fluid for signs of amyloid protein. Both techniques may be stressful for patients, expensive and require specialized equipment not available at every doctor’s office, explains Moghekar. There is a genetic test that can determine whether a person is at high risk of developing Alzheimer’s disease, but not whether they actually have it.

NIH Investments Contribute to Alzheimer’s Breakthroughs

Moghekar says funding from the National Institutes of Health (NIH) has made advances in Alzheimer’s detection and care possible. “The last decade or so has seen a big boost from NIH’s National Institute on Aging,” he says. “That’s helped the field, and that’s why we’re seeing all these breakthroughs.” Funding cuts, he says, would “risk losing that momentum.”

The Future of Alzheimer’s Diagnoses

Moghekar, who has conducted Alzheimer’s research for more than 20 years, believes this blood test is just the beginning. Other researchers are developing tests that detect tau, the protein tangles that indicate a more advanced stage of the disease. The two tests together could provide earlier, more definitive diagnoses, he says.

Published June 23, 2025.