Could having an irregular heart rhythm affect a person's risk of developing dementia?

In a large study of diverse adults in California, individuals with newly diagnosed atrial fibrillation, or an irregular heart rhythm, had a modestly elevated risk of developing dementia. The Journal of the American Heart Association study found that this risk was higher in younger adults and those without chronic kidney disease, but did not substantially vary across sex, race, or ethnicity.

In the study of nearly 200,000 adults, incidence rates for dementia over a median follow-up of 3.3 years were 2.79 versus 2.04 per 100 person-years in individuals with versus without atrial fibrillation, respectively. (This means that over one year, there would be an average of 2.79 dementia diagnoses among 100 people with atrial fibrillation and 2.04 diagnoses among 100 people without atrial fibrillation. This translates to 279 per 10,000 and 204 per 10,000.)

After adjustments, atrial fibrillation was associated with a 13% higher risk of dementia. Adults aged <65 years had a 65% higher risk compared with older adults, those without chronic kidney disease had a 14% higher risk than those with chronic kidney disease.

"These data highlight a possible link between atrial fibrillation and risk of subsequent dementia in certain populations. Further studies are needed to understand the mechanisms to explain this association, which may inform the use of treatments for atrial fibrillation," said corresponding author Nisha Bansal, MD, MAS, of the University of Washington School of Medicine.