A common skin condition may increase the risk of Parkinson's disease. New research has linked rosacea, a prevalent skin condition that causes redness and swollen red bumps on facial skin, to greater risks of new-onset Parkinson's disease in the Danish population.

The latest study, conducted at the University of Copenhagen, involved 5.4 million individuals in the Danish population. The data included 22,387 people diagnosed with Parkinson's disease and 68,053 diagnosed with rosacea.

After analyzing Parkinson's disease and rosacea rates, researchers found that there were 3.45 cases of the neurodegenerative disorder per 10,000 people and 7.62 cases of the skin condition per 10,000 people. Study results also revealed that Parkinson's disease occurred about 2.4 years earlier in patients living with rosacea.

Interestingly, patients who took the antibiotic tetracycline, which is commonly prescribed to treat rosacea, had a slightly lower risk of developing Parkinson's disease. Researchers noted that this finding held true even among individuals who don't have the skin condition.

"Rosacea constitutes an independent risk factor for Parkinson disease. This association could be due to shared pathogenic mechanisms involving elevated matrix metalloproteinase activity. The clinical consequences of this association require further study," lead researcher Alexander Egeberg, of the University of Copenhagen, and his team wrote in the study.

Researchers believe levels of a particular protein-digesting enzyme may help explain the link behind rosacea and Parkinson's disease. Previous studies have linked rosacea and neurodegenerative disorders like Parkinson's disease to higher levels of matrix metalloproteinase, an enzyme used by the body to break down proteins. They believe that the enzyme, which targets tissue activity, contributes to the loss of brain cells.

"In sum, Egeberg et al show, for what appears to be the first time, that there is a significantly increased risk of Parkinson's disease in patients with rosacea. The authors provide some tentative pathophysiologic mechanisms that could link the increased incidence of Parkinson's disease among individuals with rosacea and the reduction of Parkinson's disease incidence with tetracycline, namely, through the action, involvement or mediation of matrix metalloproteinases," Thomas S. Wingo of Emory University wrote in an accompanying editorial.

"Although this link may very well be true, what is needed at this time is for another cohort to replicate the findings of Egeberg et al, as they suggest. In addition, their intriguing finding that increased tetracycline use is associated with a small but appreciable reduction in the risk of Parkinson's disease should be further explored," added Wingo.

The findings are published in the journal JAMA Neurology.