In what scientists are hailing as a “big step forward” in Parkinson's disease research, neurologists have discovered distinct proteins in the saliva of people afflicted by the disorder — a finding that opens the door to the first simple test to diagnose the ailment early and fast-track crucial initial treatment of the debilitating illness.
The discovery, made by researchers with the Mayo Clinic in Arizona and Banner Sun Health Research Institute, suggests testing a portion of a person's saliva gland may be a way to diagnose the disease. The study is to be presented at the American Academy of Neurology's annual meeting in San Diego in March.
"There is currently no diagnostic test for Parkinson's disease," says researcher Charles Adler, M.D., a Mayo Clinic neurologist. "We have previously shown in autopsies of Parkinson's patients that the abnormal proteins associated with Parkinson's are consistently found in the submandibular saliva glands, found under the lower jaw.
“This is the first study demonstrating the value of testing a portion of the saliva gland to diagnose a living person with Parkinson's disease. Making a diagnosis in living patients is a big step forward in our effort to understand and better treat patients."
Currently, Parkinson’s is diagnosed only after the appearance of symptoms — often the characteristic shaking patients suffer — by which time the disease has usually progressed significantly and is less response to therapy. The new study could change that reality for those afflicted by the disease, which strikes up to 10 million people worldwide.
The study involved 15 people, with an average age of 68, who had Parkinson's disease for an average of 12 years, were being treated with medication, and did not have known saliva gland disorders. Biopsies were taken of two different saliva glands.
The results showed abnormal saliva proteins were detected in nine of the 11 patients who had enough tissue to examine. While still being analyzed, the rate of positive findings in the biopsies of the lower lip glands appears much lower than for the lower jaw gland.
"This procedure will provide a much more accurate diagnosis of Parkinson's disease than what is now available," said study co-author Thomas Beach, M.D., with Banner Sun Health Research Institute.
"One of the greatest potential impacts of this finding is on clinical trials, as at the present time some patients entered into Parkinson's clinical trials do not necessarily have Parkinson's disease and this is a big impediment to testing new therapies."
Parkinson's disease is a progressive disorder of the nervous system that develops gradually, sometimes starting with a barely noticeable tremor in just one finger or hand. The disorder also commonly causes stiffness and slowing of movement. Although Parkinson's disease can't be cured, medications may markedly improve symptoms.
This study was funded by the Michael J. Fox Foundation for Parkinson's Research.