The progressive nervous system condition Parkinson’s disease affects an estimated 10 million Americans each year. Characterized by muscle rigidity and tremors, Parkinson’s disease has no known cure. Now a new study is linking Parkinson’s to another painful condition: temporomandibular joint disorder.
Temporomandibular joint disorder, or TMJD, is a condition of the temporomandibular joints of the jaw. It affects an estimated 10 million Americans. Much like Parkinson’s disease, TMJ disorder can cause muscle stiffness, but it’s localized in the jaw, neck, back and shoulders.
Dr. Alexandra George practices dentistry in Wexford, Pennsylvania, where she treats patients with temporomandibular joint disorder. She says that, although the conditions are different, the symptoms of temporomandibular joint disorder have their similarities to Parkinson’s disease.
“Parkinson’s and TMJ disorder both cause muscle stiffness, but their origins are very different,” says George.
But now, thanks to a new study, researchers have revealed a new connection between the two conditions. Published in the journal PLoS One, the research out of Taiwan shows that persons with Parkinson’s disease may have an elevated risk of developing TMJ disorder.
The 13-year study examined data from National Health Insurance (NHI) recipients in Taiwan, taken from the NHI database. It followed 6,185 patients with Parkinson’s disease and 18,555 patients who did not have Parkinson’s disease. Over 50 percent of the data was extrapolated from male subjects, as men are one and a half times more likely to suffer from Parkinson’s disease, though interestingly women are more likely to suffer from temporomandibular joint disorder.
According to George, the data revealed that 32 cases of TMJ disorder appeared in the Parkinson’s disease group and 50 in the larger population – meaning those with Parkinson’s were at far higher odds of developing TMJ disorder than those in the control group.
So, what is the connection between the two conditions? George says researchers aren’t sure.
“It could be that the stiffness of the muscles experienced by Parkinson’s disease patients is being carried in the jaw as well and is triggering the temporomandibular joint disorder,” she says.
In total, the Parkinson’s disease group was over four times more likely to develop temporomandibular joint disorder than those who did not have Parkinson’s disease in the study. It also found that the longer the Parkinson’s disease patient lived, the higher their likelihood of developing temporomandibular joint disorder.