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). However, levels of oligomeric alpha-synuclein were increased in people with Parkinsons, with an average of 1.45 nanogrammes per milligramme of tear protein (ng/mg) compared to 0.27 ng/mg in people without the disease.
Parkinson's is a progressive degenerative disease of the central nervous system. Early symptoms may be mild and go unnoticed. Total levels of alpha-synuclein were decreased in people with Parkinsons, with an average of 423 picogrammes of that protein per milligram (pg/mg) compared to 704 pg/mg in people without Parkinsons.
New research from the American Academy of Neurology meeting found differences in the levels of a protein in the tears of people with and without the disease.
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.
Led by Dr. Mark Lew, the researchers chose to study tears due to the fact that they contain proteins which are produced by the tear gland in response to nerve signals.
"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 in a news release from the American Academy of Neurology. And because the disease process can begin years or even decades before the symptoms occur, a biological marker like this will be useful for early diagnosis or even for treating the disease, "Liu added".
However, that's still far in the future.
However, this method is in its first ... steps, and before that more research will have to be done to more people. The findings should be considered preliminary until peer-reviewed for publication in a medical journal.