New Research Reveals Methods to Diagnose Parkinson’s Disease in Its Earliest Stages

By Katy Mena-Berkley
Tuesday, March 30, 2021

Researchers have discovered nontraditional techniques to identify Parkinson’s disease as early as possible, offering hope for patients seeking answers during the early stages of this difficult-to-diagnose neurological condition.

Neurological diseases are notorious for being hard to diagnose; however, Parkinson’s disease is one that is particularly mysterious. Unlike some neurological diseases, such as multiple sclerosis, that can be identified through analysis of cerebrospinal fluid and MRI, Parkinson’s disease has historically been identified exclusively through a physical examination and health history. Definitive diagnoses are made only after a patient has died. The clinical diagnostic accuracy for Parkinson’s disease in its early stages has been low at roughly 50%–70%.

“Early diagnosis of Parkinson’s disease is very difficult,” says Anumantha Kanthasamy, MS, MPhil, PhD, scientist at Iowa State University. “There is no good biomarker, which is a major problem. It is a huge gap in the field.”

Addressing the Issue

In an effort to find accurate answers early, Kanthasamy led a team of researchers to examine whether a skin cell sample could be used to detect the protein alpha-synuclein and possibly help diagnose Parkinson’s disease.

“One of the challenges in brain diseases is you cannot perform biopsies like you do with other diseases,” Kanthasamy says. “We wanted to look at skin tissue samples to see if there were sensory nerves present that we could test. It was a long shot that really worked out well.”

To conduct their research, Kanthasamy and his team performed a blinded study examining 50 samples of skin, part of an assay initially designed to identify mad cow disease. The researchers were using a chemical assay to look for clumping of the alpha-synuclein protein to more accurately diagnose Parkinson’s disease.

The 50 samples the team tested were made available by the Arizona Study of Aging and Neurodegenerative Disorders (AZSAND)/Brain and Body Donation Program, which is based at the Banner Sun Health Research Institute. Half of the skin samples were from individuals with Parkinson’s disease, while the other half were from individuals who did not have any type of neurological disease. With this protein assay, 24 of 25 Parkinson’s disease patients were diagnosed, confirming to the research team that the diagnostic test is both sensitive and accurate. With this accuracy, clinicians are better positioned to make Parkinson’s disease diagnoses early and develop disease-modifying treatment options to slow progression and enhance function and quality of life.

“You might not expect skin to have biomarkers for brain disease. It is amazing for us to see this correlation,” Kanthasamy says. “The results of this research provide an encouraging opportunity to test patients with possible Parkinson’s disease. You can simply get a skin sample like a dermatologist might take — 3 to 5 millimeters — and perform a test that is not difficult to process ... This test would also be much more convenient for patients.”

Visualizing a New Diagnostic Strategy

In addition to the skin cell sample approach to early diagnosis of Parkinson’s disease, another study published in JAMA Ophthalmology examines how Parkinson’s disease may cause changes in the eyes that are detectable by noninvasive retinal imaging parameters from optical coherence tomography angiography and enhanced depth imaging optical coherence tomography.

The cross-sectional study, conducted at the Duke Neurological Disorders Clinic in Durham, North Carolina, looked at the eyes of 69 individuals with Parkinson’s disease and 137 age- and sex-matched participants with no neurological disease. All study participants were age 50 or older.

The Parkinson’s disease participants had reduced perfusion densities and retinal vessel. They also demonstrated greater choroid luminal area and total choroidal area. Compared with the healthy control patients, they showed minimized choroidal vascularity index. The results of the study indicate that this type of noninvasive retinal imaging can potentially identify structural changes related to Parkinson’s disease and could be a valuable biomarker for diagnosis of the condition.