A saliva gland test may be enough to diagnose Parkinson's disease, a new study suggests.

The study, which will be presented at the American Academy of Neurology's 65th Annual Meeting in San Diego in March, found that testing a portion of a saliva gland might be a way to determine whether a person has Parkinson's.

"There is currently no diagnostic test for Parkinson's disease," study author Dr. Charles Adler, with the Mayo Clinic Arizona and a Fellow of the American Academy of Neurology, said in a statement.

"We have previously shown in autopsies of Parkinson's patients that the abnormal proteins associated with Parkinson's are consistently found in the submandibular salivary glands, under the lower jaw, and this is the first study demonstrating the value of testing a portion of the saliva gland to diagnose a living person for Parkinson's disease," Adler said.

"Making a diagnosis in living patients is a big step forward in our effort to understand and better treat patients," he added.

Adler and his team studied 15 people with an average age of 68 who had Parkinson's disease for an average of 12 years. Researchers said that the patients had responded to Parkinson's medication and did not have known salivary gland disorders.

Researchers took biopsies from two different salivary glands in each of the participants. The two glands examined in the study included the gland just beneath the lower jaw and the minor salivary gland in the lower lip.

Researchers then stained the biopsied tissue samples and looked to see whether there was any evidence of the abnormal Parkinson's protein.

Researchers noted that there was not enough sample tissue in four of the initial lower jaw biopsies to complete the tests. However, the abnormal Parkinson's protein was detected in nine of the 11, or 82 percent, of the patients with enough tissue to study.

"While still under analysis, the rate of positive findings in the biopsies of the lower lip glands appears to be much lower than for the lower jaw gland," Adler said.

Researchers said that the latest findings provide the first "direct evidence" to support the use of lower jaw gland biopsies as a diagnostic test for patients with Parkinson's disease.

"This finding may be of great use when needing tissue proof of Parkinson's disease, especially when considering performing invasive procedures such as deep brain stimulation surgery or gene therapy," he concluded.