The pathogenesis of rosacea is unclear, but increased matrix metalloproteinase target tissue activity appears to play an important role. Parkinson disease and other neurodegenerative disorders also display increased matrix metalloproteinase activity that contribute to neuronal loss.
A study has investigated the risk of incident ( new-onset ) Parkinson disease in patients with rosacea.
A nationwide cohort study of the Danish population was conducted using individual-level linkage of administrative registers. All Danish citizens 18 years or older from January 1, 1997, to December 31, 2011 ( N = 5 472 745 ), were included.
The main outcome was a diagnosis of Parkinson disease.
A total of 5 404 692 individuals were included in the reference population; of these, 22 387 individuals ( 9812 [ 43.8% ] women; mean age at diagnosis, 75.9 years ) received a diagnosis of Parkinson disease during the study period and 68 053 individuals ( 45 712 [ 67.2% ] women; mean age, 42.2 years ) were registered as having rosacea.
The incidence rates ( IRs ) of Parkinson disease per 10 000 person-years were 3.54 ( 95% CI, 3.49-3.59 ) in the reference population and 7.62 ( 95% CI, 6.78-8.57 ) in patients with rosacea.
The adjusted incidence rate ratio ( IRR ) of Parkinson disease was 1.71 ( 95%, CI 1.52-1.92 ) in patients with rosacea compared with the reference population.
There was a 2-fold increased risk of Parkinson disease in patients classified as having ocular rosacea ( adjusted IRR, 2.03 [ 95% CI, 1.67-2.48 ] ), and tetracycline therapy appeared to reduce the risk of Parkinson disease ( adjusted IRR, 0.98 [ 95% CI, 0.97-0.99 ] ).
In conclusion, 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. ( Xagena )
Egeberg A et al, JAMA Neurol 2016;73: 529-534