The US sees around 60,000 new diagnoses of Parkinson's each year.
Middle-aged and older adults, and especially women during the menopause, are more likely to develop the condition. People with fair skin are more susceptible.
The causes of rosacea are unclear, but there is evidence that the activity of an enzyme called matrix metalloproteinase, which breaks down proteins, plays a role.
The Centers for Disease Control and Prevention (CDC) state that Parkinson's disease is the second most common neurodegenerative disease after Alzheimer's disease. The Parkinson's Disease Foundation estimate that up to 1 million Americans have the disease, and that there are 60,000 new diagnoses each year.
Early signs of Parkinson's include tremor, rigidity and difficulty walking; eventually, cognitive decline commonly occurs.
Parkinson's mostly affects older people; the risk increases from 1% at age 60 years to 4% at 80 years. It is more common among males than females.
Increased matrix metalloproteinase activity has been linked to both Parkinson's and other neurodegenerative disorders.
Onset of Parkinson's earlier for those with rosacea
Dr. Alexander Egeberg, PhD, of the University of Copenhagen in Denmark, and coauthors have been studying potential links between new-onset Parkinson's and rosacea, using data for over 5.4 million individuals.
There was a diagnosis of Parkinson's in 22,387 individuals, while 68,053 had rosacea. The rates for Parkinson's were 3.54 per 10,000 person-years, compared with 7.62 per 10,000 person-years in patients with rosacea. Patients with rosacea also tended to develop Parkinson's around 2.4 years earlier.
In people taking tetracyclines, a treatment used for rosacea, there seemed to be a slightly lower chance of Parkinson's, whether or not the patient had rosacea.
The authors conclude:
"Rosacea constitutes an independent risk factor for Parkinson disease. This association could be due to shared pathogenic mechanisms involving elevated matrix metalloproteinase activity."
While the findings indicate a potential link between rosacea and Parkinson's, the authors note that more research is needed to establish any underlying causes and other possible risk factors, and studies should include more diverse populations.
In a linked editorial, Dr. Thomas S. Wingo, of Emory University in Atlanta, GA, says this is the first research to suggest a significant association between the risk of Parkinson's and rosacea, and also calls for more research, especially into the potential effect of tetracycline on this risk.
Medical News Today recently reported that a saliva test may help to indicate the risk for Parkinson's before the disease develops.