Skin test for Parkinson's shows high accuracy in early trial

Diagnosis of Parkinson’s disease isn’t a straightforward undertaking, with physicians leaning on a combination of symptoms, clinical signs and examinations to reach their verdict. We are seeing some exciting research advances that could help reveal the condition in its earlier stages, perhaps even decades before symptoms appear, and scientists have now produced another by demonstrating how a skin biopsy can be used to identify the disease with a high degree of accuracy.

“The clinical diagnostic accuracy for early-stage Parkinson’s disease has been quite poor, only around 50-70 percent,” says Dr. Thomas Beach, a co-investigator of the study at Iowa State University. “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. Improving clinical diagnostic accuracy is, in my view, the very first thing we need to do in order to find new useful treatments for Parkinson’s disease.

Beach and his team hope to improve this diagnostic accuracy by focusing on misfolding alpha-synuclein proteins. These are seen as one of the primary triggers of Parkinson’s disease, as they clump together and are believed to drive the progressive death of the brain’s dopamine-secreting neurons, which causes the motor symptoms characteristic of the condition.

These misfolded proteins may gather in other areas of the body too, such as the gut and even our tears, and Beach and his colleagues have found through previous research that they can also accumulate in body tissues, including the skin. This raises the prospect of detecting the biomarker through skin biopsies, and indeed a number of projects are underway exploring this possibility via different mechanisms.

The new study involved 50 skin samples, half taken from patients with Parkinson’s and the other half from subjects with no neurologic disease at all. The team used a chemical assay that had been optimized specifically to detect misfolded proteins, and was able to correctly diagnose Parkinson’s disease in 24 out of 25 patients, while protein clumping was detected in just one of the controls.

“These results indicate tremendously high sensitivity and specificity which is critical for a diagnostic test,” says Dr. Charles Adler, from the Mayo Clinic, co-investigator of the study.

While the study is small, the results bode well for the pursuit of new diagnostic techniques that can pick up Parkinson’s in its early stages. This could mean new treatments that enable physicians to slow the onset of severe symptoms, or perhaps one day stop them all together.

“Since there’s no easy and reliable test available for the early diagnosis of Parkinson’s disease at present, we think there will be a lot interest in the potential use of skin samples for diagnosis,” says Iowa State’s Anumantha Kanthasamy, who led the study.

The research was published in the journal Movement Disorders.

Source: Iowa State University