Patients with Parkinson’s disease are about four times more likely to develop melanoma, and conversely, patients with melanoma have a four-fold higher risk of developing Parkinson’s, according to a study published in the July issue of the Mayo Clinic Proceedings.

The new study included 974 patients with Parkinson’s disease and compared them to 2,922 individuals without the movement disorder. The study also included 1,544 with melanoma. All of the study volunteers came from one county in Minnesota.

The researchers found that, compared with controls, patients with Parkinson’s disease had a 3.8-fold increased likelihood of having preexisting melanoma, while patients with melanoma had a 4.2-fold increased risk of developing Parkinson’s disease. The investigators said that since there is such a strong connection between these diseases, doctors treating patients for either disease should watch for signs of the other. They also recommend that doctors counsel patients about their risk of the other condition.

“Future research should focus on identifying common genes, immune responses, and environmental exposures that may link these two diseases,” first author Lauren Dalvin, M.D., of the Mayo Clinic in Rochester, Minn., said in a Mayo news release. “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.”

Here is the link to the abstract of the original article: