Author: Sean Krivitsky, Class of 2026

Parkinson’s disease is a severe neurodegenerative disorder most commonly occurring in late adulthood. It is primarily characterized by motor dysfunctions such as uncontrollable tremors and stiffness. Since there is no conclusive test for diagnosis of the disorder, neurologists rely on a comprehensive evaluation system, combining symptoms and physical assessments to gauge the likelihood that an individual has Parkinson’s.

A characteristic feature of Parkinson’s disease is diminished levels of dopamine in the brain. This led Dr. Joana Pereira of the Department of Clinical Neuroscience at the Karolinska Institutet to uncover a novel biomarker whose viability is strongly supported by this phenomenon. Specifically, the research group found DOPA decarboxylase (DDC), an enzyme that catalyzes reactions involving a dopamine precursor called L-DOPA, to be a strong biomarker candidate for various atypical Parkinson’s disorders as well as Lewy body dementia (LBD), a related disorder. They did this by collecting cerebrospinal fluid (CSF) samples from several patient controls as well as patients with various neurodegenerative disorders including Parkinson’s and LBD. These samples were then subjected to downstream analyses involving DDC.

This study found that, upon mutation of DDC, levels of several key neurotransmitters in the brain become deficient, supporting its role in the facilitation of brain function. Additionally, when analyzing patients with Parkinsonian disorders–disorders characterized by a dopamine deficiency–the researchers found that DDC levels were upregulated. This suggests a mechanism by which DDC levels increase to accommodate abnormally low levels of dopamine, thus making it a strong candidate as a biomarker for Parkinson’s disease and related disorders. Furthermore, this study integrated the use of an accepted biomarker for LBD with their proposed biomarker to suggest a future course of action in the clinical diagnosis of Parkinson’s and other related disorders. Through their analyses, they devised a method by which medical professionals could combine the use of these biomarkers in a manner that has far higher specificity and accuracy in diagnosing atypical Parkinsonian disorders than current methods.

Ultimately, this groundbreaking study reveals DDC as a promising robust biomarker of Parkinson’s disease that offers significant improvement over the limited tests currently available for diagnosis. It has the potential to not only differentiate Parkinsonian disorders from other disorders with which they are commonly confused during diagnosis, but also provide early predictions of later Parkinson’s onset.

Figure 1. Graphic portraying a man displaying symptoms characteristic of Parkinson’s disease.

Works Cited

[1] Pereira, J. B., Kumar, A., Hall, S., Palmqvist, S., Stomrud, E., Bali, D., Parchi, P., Mattsson-Carlgren, N., Janelidze, S., & Hansson, O. (2023). DOPA decarboxylase is an emerging biomarker for Parkinsonian disorders including Preclinical Lewy Body Disease. Nature Aging, 3(10), 1201–1209. https://doi.org/10.1038/s43587-023-00478-y 

[2] Image retrieved from: https://commons.wikimedia.org/wiki/File:Paralysis_agitans_(1907,_after_St._Leger).png