Skin biopsy as a potential method towards a test for Parkinson’s

Diagnosing Parkinson’s can still be very difficult. In fact, 1 in 4 people with Parkinson’s are misdiagnosed before they are diagnosed with Parkinson’s.

One reason for this is that we don’t yet have a good way to measure the changes that happen in the body that are associated with Parkinson’s. This makes it tricky to track how the condition might be progressing, as well as confirming a diagnosis. Having a medical test that could measure Parkinson’s could revolutionise how we track, treat, and diagnose the condition.

Lots of research studies are looking at potential tests for Parkinson’s. Many of these tests are set up to look for a protein called alpha-synuclein, which has been linked to Parkinson’s. Read about one promising test that hit the headlines last year.

But so far, the tests that are in development are invasive. These tests require the person to give a sample of fluid from the spine, which would then be studied to look for alpha-synuclein. This invasive procedure is not suitable for everyone. An ideal medical test would be quick and easy to do, with as little discomfort for the person as possible.

What did the researchers do?

The research team studied 428 people between the ages of 40 and 99. Everyone in the study had been diagnosed with either Parkinson’s, dementia with Lewy bodies, multiple system atrophy, or pure autonomic failure.

Dementia with Lewy bodies, multiple system atrophy and pure autonomic failure are all conditions that have similar symptoms to Parkinson’s, and can be misdiagnosed as Parkinson’s. All of these conditions are linked to a build up of alpha-synuclein causing damage to cells in the brain.

Each person in the study was asked to give 3 skin biopsies. Biopsies are small samples of skin, in this case 3mm wide, which are collected using a small, sharp tool. Samples were taken from the neck, knee and ankle, and then exposed to a dye that gives an artificial colour to the phosphorylated alpha-synuclein protein (a form of the protein that’s associated with damage in brain conditions like Parkinson’s). This allowed researchers to see if there was any of the protein in the skin sample. 

What were the results?

Results from the study showed that the test was able to correctly show a diagnosis of Parkinson’s with 93% accuracy overall. For other conditions, the test was even more accurate, with 96% of people with dementia with Lewy bodies, 98% of people with multiple system atrophy, and 100% of people with pure autonomic failure having phosphorylated alpha-synuclein in their sample.

Researchers also compared the amount of phosphorylated alpha-synuclein in samples from people who had been diagnosed more or less than 5 years ago. They found no difference in the amount of the protein, suggesting that the test could be used to spot Parkinson’s from an early stage. Further research looking at this test could help understand whether the test could also be used to distinguish between the 4 conditions.

Dr Katherine Fletcher, Research Communications Lead at Parkinson's UK, said:

"This study is one of many looking to find a simple way to accurately and more objectively identify and measure neurodegenerative conditions such as Parkinson's. Something that is currently lacking.

"This method of taking small samples of skin to be tested looks promising and patient friendly. However, the test still needs refining to further understand its accuracy and sensitivity to detect Parkinson’s and at what stage.

"Research into these types of tests is hugely important not only to improve diagnosis but to help accelerate the search for new and better treatments to transform the lives of those living with Parkinson's."