Parkinson's test (a-Synuclein seed amplification assay)

A new Parkinson's test can identify people with Parkinson's disease during the early stages or even before symptoms begin. The test is called an alpha-synuclein seed amplification assay.

Parkinson's testing reveals if there are clumps of alpha-synuclein in spinal fluid. Alpha-synuclein, also known as a-synuclein, is a protein found in Lewy bodies. Lewy bodies are substances within brain cells that are microscopic markers of Parkinson's disease.

Research has found that checking samples of spinal fluid for the proteins can identify people with Parkinson's disease. The test also detects people at risk of Parkinson's disease but who don't yet have symptoms. Removing spinal fluid for testing requires a lumbar puncture, also known as a spinal tap.

The Parkinson's test is used by researchers during clinical trials. It's not available in a health care professional's office, but there's hope that it will be used for the diagnosis of Parkinson's disease in the future. Experts also hope the test could one day be done using blood samples rather than spinal fluid.

Until now, there was no one test that could diagnose Parkinson's disease. That's still true when you see your health care professional. Health care professionals can't diagnose Parkinson's disease until you have symptoms, which include shaking and slowed movement.

But in the research setting, an a-synuclein seed amplification assay has been found to detect Parkinson's disease in the early stages and even before symptoms begin.

In the largest study of the test so far, researchers examined the spinal fluid of more than 1,000 people to look for clumps of the protein a-synuclein. The protein clumps are a hallmark sign of Parkinson's disease. Most of the time, the test accurately identified people with Parkinson's disease. The test also detected people at risk of Parkinson's disease but who didn't yet have symptoms.

Other research also has shown that a-synuclein assays can distinguish between people with Parkinson's disease and people without the disease. But larger studies are still needed.

Having a substance that can be measured to detect Parkinson's disease, known as a Parkinson's biomarker, is an important step forward. If biomarker testing for Parkinson's becomes more widely available, it would allow people to be diagnosed and start treatment early. It also would give experts more information on the subtypes of Parkinson's disease. And it would speed up clinical trials, including trials looking into new treatments.

Testing for Parkinson's disease involves getting a lumbar puncture, also called a spinal tap. During a lumbar puncture, a needle is inserted into the space between two lumbar bones, also known as vertebrae, in your lower back. Then a sample of spinal fluid is collected to be tested for a-synuclein clumps.

A lumbar puncture is generally a safe procedure, but it can carry some risks. After a lumbar puncture, you may experience:

• Headache. You may have a headache if spinal fluid leaks into nearby tissues as a result of the procedure. The headache may begin several hours or up to two days after the lumbar puncture. You also may experience nausea, vomiting and dizziness. You might notice that the headache gets worse when sitting or standing and that it gets better when you lie down. Headaches may last a few hours or up to a week or longer.
• Back pain. You may feel tenderness or pain in your lower back. It may radiate down the back of your legs.
• Bleeding. There may be bleeding at the site of the lumbar puncture. Rarely, bleeding may occur in the spinal canal.

Before a lumbar puncture, your health care professional takes your medical history and may order blood tests to check for bleeding or clotting conditions. Let your health care professional know if you have any bleeding conditions or if you take a blood thinner. Blood thinning medicines include warfarin (Jantoven), clopidogrel (Plavix), edoxaban (Savaysa), rivaroxaban (Xarelto) and apixaban (Eliquis).

Also tell your health care professional if you have an allergy to any medicines such as local anesthetics.

Follow your health care professional's instructions about food, drink and medicines before the procedure. You may need to stop taking certain medicines in the hours or days leading up to a lumbar puncture.

You'll likely go to an outpatient medical center or a hospital for the lumbar puncture. You may be given a hospital gown to wear during the procedure.

During the test

You either lie on your side with your knees pulled up to your chest or you sit on a stable surface and lean forward. In these positions, the spaces between your vertebrae widen. This makes it easier to insert the needle for removing spinal fluid. A health care professional washes your back with antiseptic soap or iodine to sterilize the area. A surgical drape covers the area.

You're given an injection of a local anesthetic to numb your lower back. You'll likely feel a pinch when the anesthetic is injected. A thin, hollow needle is inserted between the two lower vertebrae to the spinal canal. You may feel pressure in your back as the needle is inserted.

Once the needle is in place, you may be asked to change your position. Then a small amount of spinal fluid is withdrawn through the needle for testing. After the needle is removed, a health care professional applies pressure to the area to prevent bleeding. The area is covered with a bandage. The procedure takes about 45 minutes.

After the test

After the lumbar puncture, you may be asked to lie on your back or side for a few hours. This may help you avoid developing a headache. It's a good idea to rest for the remainder of the day. If you have questions, ask your health care professional about when you can return to usual activities.

If you develop a headache or back pain, your health care professional may recommend taking a pain reliever available without a prescription, such as acetaminophen (Tylenol, others). If your headache is very bad, contact your health care professional.

The sample of your spinal fluid is sent to a lab for analysis. In the lab, a special material is applied to the fluid sample. If a-synuclein clumps are present, the material lights up.