New research reveals that tears may indicate how susceptible people may be for developing Parkinson's disease, the Newburgh Gazette reports.

Tears were found to contain proteins produced by secretory cells from the tear gland, which is stimulated by nerves to turn these proteins into tears. Tears were pooled from both eyes for analysis of alpha-synuclein, CC chemokine ligand 2 (CCL-2), and DJ-1 (Parkinson's disease protein 7).

"We believe our research is the first to show that tears may be a reliable, low-cost and noninvasive biological marker of Parkinsons disease", said Mark Lew from the University of Southern California in Los Angeles.

Parkinson's disease itself is a degenerative order that affects the central nervous system.

"Our research is the first to show that tears can be a reliable, cheap and non-invasive biomarker for Parkinson's disease", Liu said.

It has been found that in the tears of Parkinson patients the alpha-synuclein protein, the "trademark" of brain disease, is up to five times higher in patients than in healthy ones.

The researched team tends to find out whether there is any change in the protein level found in tears, which can be denoted as an effect on the nervous system that guides the tear gland to work on so. Those without the disease were the same age and gender as those that do have Parkinson's. Scientists are carrying forward their research which can help to detect Parkinson's disease on early stages even before the symptoms start. Tear samples were then analyzed for four specific proteins.

The researchers observed a significant decrease in total alpha-synuclein in tears from PD patients relative to healthy controls (423.12 ± 52.6 versus 703.61 ± 136.4 pg/mg tear protein).

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. Johns Hopkins researchers say they are working with other hospitals to bring the app to more patients.