Editor’s note: This issue contains reports of interesting new findings on rosacea and other diseases. It’s important to note that these findings only suggest a potential association. To determine any cause and effect relationship, further study is required.

New studies have now shown potential links between rosacea and increased risk of the nervous system disorders Parkinson’s and Alzheimer’s diseases, in addition to a growing number of other medical conditions.^1,2

In the new findings, a research team led by Dr. Alexander Egeberg at the University of Copenhagen analyzed data from the Danish national health registry, which collects the medical history of all Danish citizens. The studies tracked the entire population of Denmark over 18 years of age – more than 5.4 million people. 

After isolating the subset of the population that had been diagnosed with rosacea, the researchers analyzed whether there was an increased likelihood rosacea patients have other medical conditions by comparing the percentage of rosacea patients diagnosed with a particular condition with the percentage of diagnoses of this particular condition in the general population. 

The scientific investigators found that all individuals with rosacea had a 1.71 times greater risk of developing Parkinson’s disease than those without rosacea, and those with ocular rosacea had a 2.03 times greater risk of developing the disorder. In addition, the average onset of Parkinson’s symptoms occurred approximately 2.4 years earlier in rosacea patients than in those without the skin disorder.

The researchers also found that patients with rosacea had a 7 percent increased risk of dementia and a 25 percent increased risk of Alzheimer’s disease in particular, compared to those who didn’t have rosacea. Women with rosacea showed a greater increased risk of Alzheimer’s disease than men with the disorder (28 percent vs. 16 percent). Rosacea patients over 60 years old had a 20 percent greater risk of Alzheimer’s disease, while younger age groups showed no significant increased risk. 

The basis for a connection between rosacea and neurodegenerative disorders like Parkinson’s and Alzheimer’s is unknown, though matrix metalloproteinases (MMPs) and antimicrobial peptides (AMPs) may play a role. These proteins are present in all animals and play a role in the innate immune system and other cellular functions. Increased levels of MMPs and AMPs have been implicated in several inflammatory diseases, and have been studied as a potential cause of inflammation in rosacea.

Recent recognition of the involvement of the nervous system in rosacea, including symptoms such as burning and stinging, painful skin, facial flushing, migraine and other symptoms, also supports these findings, the researchers said. They further noted that a previous study had found increased MMP activity in the tear fluid of patients with ocular rosacea.

The researchers pointed out that although the study suggests a potential connection between these disorders, it does not necessarily mean that a causal relationship exists, and noted that because of the homogeneity of the Danish population, the results may not be extrapolated to other ethnicities.

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