The Motivations for Using Tears to Confirm Parkinson Disease Diagnosis: Mark Lew, MD

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The director of the Division of Movement Disorders at the USC Keck School of Medicine commented on the potential of reflex tears as a critical biomarker of Parkinson disease. [WATCH TIME: 6 minutes]

WATCH TIME: 6 minutes

"It made sense to try and look at the proteinaceous constituents of tear fluid. Additionally, tear fluid is easy to collect. It’s noninvasive, inexpensive. It’s not like when you do a lumbar puncture, which is a much more involved ordeal, there’s risk of contamination with blood, saliva is dirty, issues with blood and collection. It’s much safer and less expensive to do."

In an analysis presented at the 2022 American Academy of Neurology (AAN) Annual Meeting, April 2-7, in Seattle, Washington, investigators assessed whether the protein composition of reflex tears differs in patients with Parkinson disease (PD) stratified by disease duration. The study collected reflex tears of 77 men and women in early (disease duration, 0-4 years), 43 intermediate (5-8 years), and 50 late (greater than 9 years) stages of PD and 67 healthy controls. All told, oligomeric α-synuclein levels found in tear fluid did not discriminate between various stages of PD based on disease duration compared with HC.

Values measured by enzyme-linked immunosorbent assay, or ELISA, showed a 5.4-fold increase in oligomeric α-synuclein in those with early-stage PD (4.28 [±0.75] ng/mg tear protein; P <.001), a 4.0-fold increase for intermediate PD (3.23 [±0.54] ng/mg tear protein; P <.001) and a 3.1-fold increase for late-stage PD (2.44 [±0.40] ng/mg tear protein; P <.001). Led by Mark Lew, MD, the study expanded on previous findings which first identified these elevated protein levels in both basal tears and reflex tears.

In an interview with NeurologyLive^®, Lew, director of the Division of Movement Disorders at the USC Keck School of Medicine, echoed the thoughts of other movement disorder experts, noting the dire need for biomarkers of PD that can formalize diagnosis and show medication response. He also provided background on the previous that led to this new analysis, how tears are collected, and the advantages they bring over traditional biomarkers.

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