Lauren A. Dalvin, M.D.

People with either Parkinson’s disease or melanoma are four times as likely to receive a diagnosis of the other disease, according to a recent Mayo Clinic study.

The association likely is not due to a Parkinson’s drug, levodopa, that often is cited as a reason for the relationship, according to the researchers. Researchers in this study said their results make that unlikely. They found that the majority of melanomas were diagnosed before the diagnosis or treatment of Parkinson’s disease.

“It is more likely that there are common environmental, genetic or immunologic abnormalities underlying both conditions in these patients, but future research is necessary to confirm and better characterize the underlying cause of this relationship,” the authors wrote.

Future research, they suggested, should focus instead on identifying common genes, immune responses and environmental exposures that could cause the relationship.

“If we can pinpoint the cause of the association between Parkinson’s disease and melanoma, we will be better able to counsel patients and families about their risk of developing one disease in the setting of the other,” said Lauren Dalvin, M.D., first author of the study and a Mayo Foundation Scholar in Ocular Oncology.

The study used records from the Rochester Epidemiology Project to obtain data on people with Parkinson’s disease and people with melanoma. It was published in Mayo Clinic Proceedings.