Tears May Be Used as Biological Marker to Detect Parkinson’s Disease

Tears May Be Used as Biological Marker to Detect Parkinson’s Disease

Tears may be used to diagnose Parkinson’s disease, according to preliminary findings of a study that will be presented at the 2018 American Academy of Neurology’s (AAN) Annual Meeting in Los Angeles, California, April 21-27.

“We believe our research is the first to show that tears may be a reliable, inexpensive and noninvasive biological marker of Parkinson’s,” Mark Lew, MD, the study’s author from the Keck School of Medicine of University of Southern California, said in a press release.

Parkinson’s disease is mainly characterized by selective loss of neurons that produce dopamine in a brain area called substantia nigra. Patients with Parkinson’s typically exhibit Lewy bodies – protein clumps mainly composed of aggregated alpha-synuclein – in the brain, leading to nerve damage and disease progression.

Besides pathological changes in the brain, the disease also affects nerve function in the periphery. As the secretory cells of the tear gland are stimulated by nerves, researchers hypothesized that nerve changes in Parkinson’s could result in altered protein levels in tears.

The scientists collected tear samples from 55 Parkinson’s patients and 27 healthy controls who were the same age and gender.

The tears were analyzed for the levels of four proteins. The results revealed that levels of normal, non-clumped alpha-synuclein were lower in Parkinson’s patients than in controls. However, levels of unhealthy, aggregated alpha-synuclein were increased in tears of Parkinson’s patients  (1.45 nanograms per milligram of tear proteins versus 0.27 nanograms, respectively).

Researchers hypothesize that the secretory cells in the tear gland could themselves produce these different forms of alpha-synuclein, which would be secreted directly into tears.

“Knowing that something as simple as tears could help neurologists differentiate between people who have Parkinson’s disease and those who don’t in a noninvasive manner is exciting,” Lew said.

“And because the Parkinson’s disease process can begin years or decades before symptoms appear, a biological marker like this could be useful in diagnosing, or even treating, the disease earlier,” he added.

Nonetheless, larger studies need to be done to evaluate whether these changes in alpha-synuclein levels can be detected in tears from Parkinson’s patients before symptoms start.


  1. Suzi Smith says:

    In the past 2 yrs my 68 yr old husband Dean has had 3 cornea transplants + cataract removal + does not drive, 2 pacemakers put in last one with a 3rd lead + now Afib , gone deaf but now has hearing aids, a horrible foot fungus + yes Parkinson’s. I have known for a long time there was something like that going on! But his GP said no + not until he had a reaction to the anesthetic after an eye surgery did his wonderful Opthamoligist tell him he had Parkinson’s + was to go straight to his new Internist + Neurologist who then confirmed it. He is now on carbidopa / levodopa which helps tremors + falling issues. He goes to the YMCA class for Parkinson’s (Big Thank you to JJ and YMCA). He also works 20 hrs a week. I can’t help but think this disease has been with him for some time. However at the support groups I have gone to no one has all the problems Dean has. Any information you have that would help us would be greatly appreciated . Thank you, Dean + Suzi Smith

    • Hi Dean and Suzi, I understand exactly how you feel as my husband, Arthur, in the past 11 years has had two open-heart surgeries, prostate operations, gall bladder operation and recently declined an electrophysiology procedure for atrial fibrillation as he’d already gone through two attempts to fix his at.fib about the time he was diagnosed with heart failure. He was recently diagnosed with Parkinson’s disease but we’re pretty sure he had symptoms for many years previous, just as you thought. Arthur has levodopa/benserazide 100mg/25mg which was given to him as a lower dose didn’t help. He takes this three times daily but I feel he’ll need an extra dose soon as it wears off after 3 hrs. He has very slow gait, freezing and dragging of his feet quite a lot and now cannot life feet over shower edge himself. He’s 79 yrs. of age. He thinks he’s past going to a support group for exercises but I may go to meet others and see what they do, plus socialize. This may or may not help you. Barb Kelly

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