Testing for Parkinson’s: Could a simple skin test help diagnose Parkinson’s sooner?

For people experiencing symptoms of Parkinson’s disease—like tremors, loss of balance or slow movement—getting to a diagnosis can be challenging. Early symptoms are often subtle and can be confused with other, more benign conditions such as an essential tremor.

Fortunately, advancements like skin testing are making it easier to diagnose the condition earlier, improving the care and quality of life for people with Parkinson’s disease. Here’s what to know about the skin biopsy test for diagnosing Parkinson’s.

Latest research on testing for Parkinson’s

A study published in the Journal of the American Medical Association (JAMA) in March 2024 is the latest in a string of papers validating evidence for the use of skin biopsies, or skin tests, for the detection of Parkinson’s disease and related disorders. This study is the largest to date, with 428 participants across 30 sites.

The results, in line with previous studies, showed a very high degree of reliability (92.7%) in detecting a certain marker for Parkinson’s disease.

This research is an exciting step forward for Parkinson’s care because it means we can confidently use this skin test to make earlier and more accurate diagnoses for people with potential Parkinson’s symptoms.

The biopsy test allows us to diagnose Parkinson’s in people who may have very mild symptoms and may not fully meet the formal criteria for Parkinson’s. Early detection helps people understand the cause of their symptoms, which can often be distressing and otherwise go without a clear diagnosis for many more months or even years.

While there are no treatments yet available to slow or reverse Parkinson’s, early diagnosis can empower people to make appropriate lifestyle changes to better manage their condition and start treatments earlier that may improve their quality of life.

Accelerating Parkinson’s disease diagnosis

Traditionally, Parkinson’s disease has been diagnosed based on a physical examination and your medical history. This remains true for the vast majority of Parkinson’s diagnoses, as the condition has had clearly established clinical criteria for decades.

But sometimes, the symptoms are vague or ambiguous, making a diagnosis more challenging. In those cases, there are testing options available that help us get closer to pinpointing the cause of a person’s symptoms, but they have limitations.

A diagnostic scan using nuclear medicine (known as DaTscan) has been available since 2011 to aid in the diagnosis of Parkinson’s. This scan helps evaluate dopamine transmission in the brain. Dopamine is a neurotransmitter associated with movement, mood and motivation, and a dopamine tracer is a substance used to measure its levels in the brain. If there is a deficiency in dopamine tracer uptake, it is suggestive of Parkinson’s or a related condition (a group of conditions collectively known as neurodegenerative parkinsonian syndromes).

But there are some key limitations in the use of DaTscan, including medication interference, allergies, physical requirements to lie flat and the inability to differentiate between Parkinson’s and other neurodegenerative parkinsonian syndromes.

The new skin biopsy test (known commercially as the SynOne test) uses a microscope to look at the nerve layer just beneath the skin, searching for a marker (a a biological substance or characteristic) called phosphorylated alpha-synuclein.

One key difference between DaTscan and SynOne testing is that SynOne does have the ability to differentiate between two major groups of parkinsonian disorders. The SynOne test specifically allows us to detect whether a person has one of the disorders known as synucleinopathies, which includes Parkinson’s disease, dementia with Lewy bodies (DLB) and multiple system atrophy (MSA). It doesn’t test positive for the other group of disorders in the broader group, which are called tauopathies, such as progressive supranuclear palsy (PSP) and corticobasal degeneration (CBD).

This means we can more accurately diagnose the cause of any symptoms, bringing you clarity and confidence in your treatment plan.

How the skin test for Parkinson’s disease works

So, how does it work? The skin biopsy test involves a very simple office procedure. We’ll take three small (3 mm) punch biopsies of your skin from pre-selected areas of the body: the back of the neck, the side of the lower thigh and the side of the outer ankle.

These biopsies are done under local anesthesia and require no stitches and minimal after-care. The results are usually available within a few weeks after the samples are sent to the lab for analysis. The procedure typically takes around 20 minutes and involves minimal discomfort. If you are on blood thinners, you may have to hold your medication for a short time.

Like any test, there is a small chance of a false negative (although there is virtually no chance of a false positive). This test is extremely accurate, detecting 92.7% of Parkinson’s cases.

Also, while this test is a bit more specific—helping us differentiate between the two big groups of parkinsonian syndromes—it still does not tell us if a person has Parkinson’s versus another synucleinopathy.

Your doctor can discuss the testing options with you to help determine the best step for you. This skin biopsy test may be a good option for people who:

• Experience Parkinson’s-like symptoms who may not fully meet the clinical criteria
• Do not respond to medications as expected after meeting the other criteria
• Have symptoms that resemble Parkinson’s but are taking certain medications known to cause similar symptoms and need clarification to rule out drug-induced parkinsonism

This test is available at select movement disorder centers and neurology clinics nationwide and is becoming more widely available. Our movement disorder center at Baylor Scott & White has been one of the earliest sites in the region to offer this test, as we have been routinely using it since April 2022.

The future of Parkinson’s research and treatment

Researchers continue to explore ways to better diagnose and treat Parkinson’s disease and similar disorders. One of the big challenges with finding a cure for Parkinson’s disease is that once the symptoms start, it progresses quickly and it’s usually too late for any treatment to reverse the condition.

The hope for advancements like this skin test that can diagnose Parkinson’s earlier, when symptoms are still minor, is the opportunity to test potential new medications and treatments that may help slow—and one day cure—Parkinson’s disease.

If you or a loved one is experiencing symptoms of Parkinson’s disease, you’re not alone. Find a neurologist near you and get answers today.