Testing tears may be a reliable, inexpensive and non-invasive way to diagnose Parkinson's disease early, a study has found.
Researchers investigated tears because they contain various proteins produced by the secretory cells of the tear gland, which is stimulated by nerves to secrete these proteins into tears.
First off, what is Parkinson's disease?
Parkinson's disease affects the way you move. It happens when there is a problem with certain nerve cells in the brain.
Normally, these nerve cells make an important chemical called dopamine. Dopamine sends signals to the part of your brain that controls movement.
When you have Parkinson, these nerve cells break down. Then you no longer have enough dopamine, and you have trouble moving the way you want to.
Tears were analyzed for the levels of four proteins
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 of the same age and gender.
Interestingly, researchers found differences in the levels of a particular protein, alpha-synuclein, in the tears of people with Parkinson's.
What do the researchers have to say?
"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 Mark Lew from the University of Southern California in Los Angeles.
"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," he said.