In Parkinson’s disease (PD), there is chronic degeneration of the central nervous system, particularly in the regions involved with controlling the motor system. As a result, patients experience tremors, rigidity, and difficulties with walking and coordination. Around 60,000 Americans are diagnosed with PD every year and over 10 million people around the world are living with the condition. Diagnosing PD, particularly at the early stages, continues to be a challenge and many are at advanced stages of the disease by the time they seek medical help.
“The clinical diagnostic accuracy for early-stage PD has been quite poor, only around 50-70%,” said Thomas Beach, a researcher developing new and improved methodologies for diagnosing PD. “And since clinical trials really need to be done at an early stage to avoid further brain damage, they have been critically hampered because they have been including large percentages of people who may not actually have the disease.”
In a recent study, Beach and the team have made a breakthrough: a simple skin test for PD. This chemical assay was designed to detect alpha-synuclein (a protein biomarker present in the brains and other tissues of PD patients) that serves as a positive indicator of the neurodegenerative condition.
The team validated their innovation using 50 skin samples obtained from the study participants, half of which already had a PD diagnosis. Promisingly, the assay correctly diagnosed 96 percent of the PD patients with levels of sensitivity and specificity critical for a robust and accurate diagnostic test.
The skin-based diagnostic test was based on an existing assay originally created for detecting bovine spongiform encephalopathy (BSE), commonly known as mad cow disease. The team from Iowa State University has spent several years building upon this foundation, adapting and optimizing the assay to detect the presence of misfolded proteins, specifically misfolded alpha-synuclein in the case of PD.
Over time, these misfolded proteins tend to build up and accumulate in brain tissues, resulting in the disruption of neural function. These misfolded proteins don’t just pile up in the brain, however, and can also be found in trace amounts in other anatomical locations, including the skin.
According to the study, earlier detection of PD is a stepping stone towards earlier, more effective clinical intervention as well as improved testing strategies for therapeutics in development.