A study published in the Annals of Neurology has uncovered an increased risk of dementia in patients with rosacea.
Importantly, the risk was highest in older patients and in patients where rosacea was diagnosed by a hospital dermatologist.
The study included 5,591,718 Danish citizens aged older than 18 years 82,439 patients with rosacea. Individuals were followed until December 31, 2012, migration, a diagnosis of dementia, or death from any cause, whichever came first.
A total of 99,040 individuals developed dementia, of which 29,193 were diagnosed with Alzheimer's disease.
After adjustments for potential confounding factors, patients with rosacea had a 7% increased risk of dementia and a 25% increased risk of Alzheimer's disease compared with individuals without rosacea.
Stratified by sex, women had a 28% increased risk of Alzheimer's disease and men had a 16% increased risk if they had rosacea.
When results were stratified by age at study entry, the risk of Alzheimer's disease was only significantly increased in individuals aged 60 years and older (20% increased risk).
When analyses were limited to patients with a hospital dermatologist diagnosis of rosacea only, the increased risks of dementia and Alzheimer's disease were 42% and 92%, respectively.
"A subtype of patients have prominent neurological symptoms such as burning and stinging pain in the skin, migraines, and neuropsychiatric symptoms, suggesting a link between rosacea and neurological diseases," said Alexander Egeberg, MD, University of Copenhagen, Copenhagen, Denmark.
"Indeed, emerging evidence suggests that rosacea may be linked with neurological disorders including Parkinson's disease and now also Alzheimer's disease," he said. "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."
The results may provide new insights into the link between the skin and neurodegenerative disorders. Further research is warranted to examine whether treating rosacea may also modify patients' risk of developing dementia.