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Can analysing tears help diagnose Parkinson’s early?

Original article: Exenatide once weekly versus placebo in Parkinson’s disease: A randomized, double-blind, placebo-controlled trial, The Lancet: August 3, 2017. 

Media portrayal:
Scientific interpretation:

Can analysing tears help diagnose Parkinson’s early?

The takeaway

Early findings suggest that a-synuclein, the protein which causes neuronal damage in Parkinson’s, can be detected in tears. In a recent study, it was found to be elevated in a group of people with Parkinson’s compared to age-matched counterparts.

Why is it important?

These early findings on the composition of tears open up the possibility that they could be used as an inexpensive and non-invasive biological marker for Parkinson’s.



  • Novelty 70% 70%
  • Proximity 30% 30%
  • Deliverability 40% 40%

Impact Opinion

“This is an exciting preliminary report. It will be important, however, to wait for the peer-reviewed publication before drawing any major conclusions.”


a-Synuclein is a protein with several possible functions, one of which is to regulate communication between nerve cells. In Parkinson’s, clumps of abnormal a-synuclein (known as oligomers) actually cause damage, and can be found in nerve cells both in the brain but also in other parts of the body, such as the gut and nose.

Tear glands receive signals from the brain through neurons. These researchers reasoned that higher levels of a-synuclein oligomers might be produced by the tear glands themselves or as a result of stimulation by nerves carrying this substance.

The details

Tear samples from 55 people with Parkinson’s and 27 age and gender-matched individuals were analysed. Although a-synuclein itself was lower, the harmful, oligomeric type which is known to cause neuronal damage was more than 5 times higher in people with Parkinson’s.

These results were announced ahead of the study’s publication; this article will be updated as soon as the full study is published and available.

Next steps

This is a small study and more work will be required to replicate these interesting findings in a larger group of people. Currently, this study relates to people with an existing diagnosis of Parkinson’s. The next step is to roll this work out in a large cohort of people, in an attempt to capture changes at the earliest stages, before symptoms actually appear.

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