The chronic inflammatory disorder is marked by certain increased proteins, which are also active in some neurodegenerative disorders, the authors from the University of Copenhagen found.
“Emerging evidence suggests that rosacea may be linked with neurological disorders including Parkinson’s disease and now also Alzheimer’s disease,” said Alexander Egeberg, lead author of the study in the Annals of Neurology.
More than 5.5 million Danish citizens older than 18 were analyzed between 1997 and 2012, according to the paper. More than 82,000 patients had rosacea, and just under 100,000 developed dementia (29,000 of whom had Alzheimer’s), according to the doctors.
When adjusted for various factors, rosacea had a seven percent increased risk of dementia – and a 25 percent increased risk of Alzheimer’s, they found. By gender, women had a 28 percent greater chance of Alzheimer’s, and for men the increase was 16 percent.
When limited to only patients older than 60 with a diagnosis of rosacea, the risk of dementia increased by 42 percent and the incidence of Alzheimer’s increased 92 percent.
“There are certain mechanistic overlaps between rosacea and Alzheimer’s disease that may explain the observed association, albeit the pathogenic links between these conditions are still unclear,” Egeberg said.
The proteins shared between the skin and brain diseases include matrix metalloproteinases and antimicrobial peptides, according to the researchers.
However, the correlation in how they are causative or symptomatic has yet to be determined.
“There are certain mechanistic overlaps between rosacea and Alzheimer’s disease that may explain the observed association, albeit the pathogenic links between these conditions are still unclear,” said Egeberg.
The inflammatory aspects of rosacea are still not well understood - although it is known to be genetic in nature. The causes of Alzheimer's are also not well understood - although some researchers are pointing toward findings that it is an autoimmune condition.