Blood Test to Detect Alpha-Synuclein Protein Could Revolutionize Parkinson's Disease Diagnostics

There is a pressing need for an objective and quantifiable biomarker for early diagnosis of this prevalent movement disorder. Research has demonstrated that the pathophysiologically significant protein alpha-synuclein, known to accumulate in the nerve cells of PD patients, can also be found in various body fluids and tissues, such as cerebrospinal fluid or skin. Now, researchers have discovered that a blood test for detecting alpha-synuclein could offer a feasible, less invasive method for diagnosing PD.

Previously, a research team at University Hospital Schleswig-Holstein (UKSH, Kiel, Germany) had demonstrated that alpha-synuclein could be detected in the blood of PD patients by isolating neuronal exosomes, or small vesicles from neuronal cells, in the blood and amplifying the contained alpha-synuclein using a seed amplification assay (SAA). Their latest study, published in the Journal of Parkinson's Disease, sought to validate the efficacy of this blood test in a broader cohort of PD individuals and to investigate how alpha-synuclein levels, as measured by SAA, may vary as the disease progresses.

In this study, researchers analyzed cross-sectional blood samples from PD patients and compared them with those from age- and gender-matched healthy controls using the blood-based SAA. Out of 80 PD patients tested, 79 showed positive results for alpha-synuclein seeding in the blood, whereas none of the healthy controls tested positive. This high sensitivity of the alpha-synuclein blood marker for PD was thus confirmed. Additionally, when analyzing subgroups of PD patients with varying disease durations, those with longer disease durations exhibited lower alpha-synuclein seeding activity. This indicates that alpha-synuclein seeding activity may change throughout the disease's progression. However, it is still uncertain how alpha-synuclein seeding activity naturally evolves over the course of PD.

"There is currently no blood test for PD available in clinical practice. It is of course of great importance that the strong results of our cross-sectional and longitudinal analyses are validated and replicated in different labs. If the decline in seeding activity in blood was confirmed, it may influence further studies and our understanding of disease progression,” said lead investigators Annika Kluge, MD, and Eva Schaeffer, MD, both of the Department of Neurology, University Hospital Schleswig-Holstein. “In the long term, it is hoped that this blood test can be used to improve the diagnostic security and reliability in PD, even at early stages during which clinical diagnosis is difficult. Moreover, the impact on clinical studies needs to be considered, especially regarding the potential of antibody-based targeted treatments for PD."

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