Years ago, the only way to know for sure if someone had Alzheimer’s disease was to examine their brain after they died. Now, doctors and researchers can use blood tests, along with other diagnostic tools, to diagnose Alzheimer’s while someone is still living. Getting an early diagnosis can help healthcare providers offer new treatments and lifestyle suggestions that will support brain function and quality of life as long as possible.

Here are seven facts about blood tests for Alzheimer’s. If you’re interested in finding testing for yourself or someone you love, schedule an appointment with your primary care provider. Depending on what they find, they may refer you to a neurologist or other healthcare professional.

1. Blood Tests Look for Proteins

When doctors and researchers examine a person’s brain with a microscope to confirm an Alzheimer’s diagnosis after death, they look for plaques and tangles. Plaques are sticky buildups of beta-amyloid proteins that collect between nerve cells. Tangles are strands of tau proteins that clump together and twist around each other. Plaques and tangles disrupt cell communication and cause brain cells to die. The more amyloid plaques and tau tangles someone has, the worse their Alzheimer’s symptoms.

Alzheimer’s blood tests can detect signs of plaques and tangles while someone is still alive. With a small blood sample, doctors use these tests to look for biomarkers that indicate whether beta-amyloid and tau proteins are present in the blood. This information can help provide an accurate diagnosis. It can also help doctors monitor disease progression.

2. Blood Tests Are Only One Tool

Although blood tests can help lead to an Alzheimer’s diagnosis, they are just one of several diagnostic tests and tools healthcare professionals use. Blood tests should not be used alone.

Other biomarker tests used to detect Alzheimer’s include a type of brain imaging called positron emission tomography, also known as a PET scan, and cerebrospinal fluid (CSF) testing. CSF testing requires a small sample of spinal fluid taken through a spinal tap or lumbar puncture.

Alzheimer’s diagnosis may also include CT or MRI scans, physical and neurological exams, and cognitive testing.

Everyone’s journey to a diagnosis will be slightly different. Your neurologist or other specialist should explain which tests you need and why. While new blood tests are improving the diagnostic process for Alzheimer’s, they are still just one of several tools that provide unique information to complete the broader picture.

3. Blood Tests Are Used When Someone Is Showing Symptoms

Alzheimer’s blood tests are generally used when someone is showing cognitive symptoms, like memory problems or trouble performing daily tasks. These are signs that someone may be in the early stages of Alzheimer’s or dementia. It may also mean they are having another medical issue, like medication side effects or a sleep disorder. When used as part of a comprehensive exam, blood tests can help healthcare providers understand if you have Alzheimer’s or another condition that might cause cognitive impairment.

4. Blood Tests Can’t Predict the Future

If you have a family history of Alzheimer’s, you might find it tempting to take a blood test to find out if you’re at risk of developing the disease. However, doctors recommend against taking a test without symptoms because there is currently no Alzheimer’s treatment strategy for those who test positive but don’t show signs of cognitive decline. Also, testing positive for blood biomarkers doesn’t guarantee you will develop Alzheimer’s. It just means your risk is higher. Testing positive before showing symptoms could cause unnecessary stress and anxiety. In some cases, it could also affect your insurance.

5. Blood Tests Are Accurate

In a study done at Lund University in Sweden, researchers found that blood tests may outperform primary care providers and specialists in detecting Alzheimer’s.

Researchers found that the blood test they used in the study was about 90 percent accurate at identifying Alzheimer’s. In comparison, memory clinic specialists were 73 percent accurate, and primary care providers were correct in 63 percent of cases.

Several companies are developing Alzheimer’s blood tests. Accuracy may vary by test. The Alzheimer’s Association recommends more research and standardization to ensure reliable results before these tests are routinely used in clinical practice. The National Institute on Aging recommends additional testing in more diverse populations.

6. Blood Test Accessibility and Prices Vary

Healthcare providers in the United States can order Alzheimer’s blood tests when they suspect a person may have Alzheimer’s or another type of dementia. These tests should only be used by specialists and as part of a comprehensive evaluation. If you’re interested in getting a blood test for yourself or a loved one, talk to a healthcare professional.

If your doctor requests a test, you will likely pay for it out of pocket. Be sure to ask for an estimate up front, as prices can vary by hundreds of dollars. Some manufacturers offer patient assistance programs. Researchers expect some of these tests will be FDA-approved and covered by insurance in the next few years.

7. Blood Tests Are the Future

Alzheimer’s research has led to advances in diagnosis and treatment. In May 2025, the FDA cleared the first blood test that can be used to diagnose Alzheimer’s. It has also granted “breakthrough device” designation (a status that speeds up FDA review) to several others, which could accelerate the approval process. Making it easier to get diagnosed could lead to earlier detection and better outcomes.

This information continues to evolve. Schedule an appointment with your healthcare provider for questions and updates.

Talk With Others Who Understand

On myALZteam, the social network for people with Alzheimer’s and their loved ones, more than 86,000 members come together to ask questions, give advice, and share their stories with others who understand life with Alzheimer’s disease.

Have you or a loved one had a blood test for Alzheimer’s? What did you learn? Share your experience in the comments below or on your Activities page.