Shedding a tear may help diagnose Parkinson's disease

February 22, 2018, American Academy of Neurology
Immunohistochemistry for alpha-synuclein showing positive staining (brown) of an intraneural Lewy-body in the Substantia nigra in Parkinson's disease. Credit: Wikipedia

Tears may hold clues to whether someone has Parkinson's disease, according to a preliminary study released today that will be presented at the American Academy of Neurology's 70th Annual Meeting in Los Angeles, April 21 to 27, 2018.

"We believe our research is the first to show that tears may be a reliable, inexpensive and noninvasive biological marker of Parkinson's disease," said study author Mark Lew, MD, of the Keck School of Medicine of the University of Southern California in Los Angeles and a Fellow of the American Academy of Neurology.

Lew says the research team investigated tears because they contain various proteins produced by the of the tear gland, which is stimulated by nerves to secrete these proteins into tears. Because Parkinson's can affect outside of the brain, the research team hypothesized that any change in nerve function may be seen in the in tears.

For the study, tear samples from 55 people with Parkinson's were compared to tear samples from 27 people who did not have Parkinson's but who were the same age and gender. Tears were analyzed for the levels of four proteins.

Researchers found differences in the levels of a particular protein, alpha-synuclein, in the tears of people with Parkinson's compared to controls. Additionally, levels of another form of alpha-synuclein, oligomeric alpha-synuclein, which is alpha-synuclein that has formed aggregates that are implicated in nerve damage in Parkinson's, were also significantly different compared to controls. It is also possible that the tear gland secretory cells themselves produce these different forms of alpha-synuclein that can be directly secreted into tears.

Total levels of alpha-synuclein were decreased in people with Parkinson's, with an average of 423 picograms of that protein per milligram (pg/mg) compared to 704 pg/mg in people without Parkinson's. But levels of oligomeric alpha-synuclein were increased in people with Parkinson's, with an average of 1.45 nanograms per milligram of tear protein (ng/mg) compared to 0.27 ng/mg in people without the disease. A picogram is 1,000 times smaller than a nanogram.

"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," said Lew. "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."

More research now needs to be done in larger groups of to investigate whether these protein changes can be detected in in the earliest stages of the disease, before symptoms start.

Explore further: Calcium may play a role in the development of Parkinson's disease

Related Stories

Calcium may play a role in the development of Parkinson's disease

February 19, 2018
Researchers have found that excess levels of calcium in brain cells may lead to the formation of toxic clusters that are the hallmark of Parkinson's disease.

Protein levels in spinal fluid correlate to posture and gait difficulty in Parkinson's

February 21, 2018
Levels of a protein found in the brain called alpha-synuclein (α-syn) are significantly lower than normal in cerebrospinal fluid collected in Parkinson's disease patients suffering from postural instability and gait difficulty, ...

Drug discovery: Alzheimer's and Parkinson's spurred by same enzyme

July 3, 2017
Alzheimer's disease and Parkinson's disease are not the same. They affect different regions of the brain and have distinct genetic and environmental risk factors.

Tug of war between Parkinson's protein and growth factor

September 18, 2017
Alpha-synuclein, a sticky and sometimes toxic protein involved in Parkinson's disease (PD), blocks signals from an important brain growth factor, Emory researchers have discovered.

A new insight into Parkinson's disease protein

July 28, 2017
Abnormal clumps of certain proteins in the brain are a prominent feature of Parkinson's and other neurodegenerative diseases, but the role those same proteins might play in the normal brain has been unknown.

Re­search­ers cor­rect Par­kin­son's mo­tor symp­toms in mice

December 15, 2016
A research group led by University of Helsinki Docent Timo Myöhänen has succeeded in correcting the motor symptoms associated with Parkinson's disease in mice. These results are promising in terms of treatment, since Parkinson's ...

Recommended for you

Early synaptic dysfunction found in Parkinson's Disease

May 24, 2018
Northwestern Medicine scientists identified a cellular mechanism that leads to neurodegeneration in patients with Parkinson's disease, according to a study published in Proceedings of the National Academy of Sciences.

Study uncovers cause of pesticide exposure, Parkinson's link

May 23, 2018
A new University of Guelph study has discovered why exposure to pesticides increases some people's risk of developing Parkinson's disease.

Link between tuberculosis and Parkinson's disease discovered

May 22, 2018
The mechanism our immune cells use to clear bacterial infections like tuberculosis (TB) might also be implicated in Parkinson's disease, according to a new collaborative study led by scientists from the Francis Crick Institute ...

Link between IBD and Parkinson's might allow doctors to slow down condition

May 21, 2018
Doctors may be able to modify or slow down the progress of the neurological condition Parkinson's disease in the future by spotting signs of it in patients with inflammatory bowel disease (IBD), suggest a study published ...

Untangling brain neuron dysfunction in Parkinson's disease and dementia with Lewy bodies

May 10, 2018
A decay of brain function is a hallmark of Parkinson's disease and dementia with Lewy bodies, or DLB. Specifically, cognitive dysfunction defines DLB, and nearly eight of every 10 Parkinson's patients develop dementia.

Diverse Parkinson's-related disorders may stem from different strains of same protein

May 9, 2018
Different Parkinson's-related brain disorders, called synucleionpathies, are characterized by misfolded proteins embedded in cells. Researchers in the Perelman School of Medicine at the University of Pennsylvania found that ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

DementechUK
not rated yet Feb 23, 2018
This is, most definitely, an intriguing study. We look forward to seeing this progress!

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.