Thanks olsen.
The Abstract of the Danish study referred to in your link is here
Exploring the Association Between Rosacea and Parkinson Disease: A Danish Nationwide Cohort Study. - PubMed - NCBI.
It looks impressive to me - there were more than 5 million subjects in the study. It is interesting that tetracycline therapy for rosacea appeared to lead to a small reduction in the risk of Parkinson's disease.