Newly-diagnosed atrial fibrillation (AF), or an irregular heart rhythm, gave individuals a modestly elevated risk of developing dementia in a large California-based study of diverse adults.
Risk was higher in younger adults and those without chronic kidney disease, but did not substantially vary across sex, race, or ethnicity. The authors point out that determining whether AF increases the risk of dementia could affect treatment decisions.
In this study, AF 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.
The team’s report was published in the Journal of the American Heart Association. The lead author is Nisha Bansal, MD, MAS, of the University of Washington, Seattle.
“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 Bansal.
AF is the most common, clinically relevant arrhythmia in adults and associated with ischemic stroke and premature death. Its incidence has increased three-fold over the last 50 years, and it was estimated that worldwide prevalence was around 46.3 million in 2016.
This condition is associated with a number of factors. One question that has arisen is whether it is linked to higher risk of dementia. But there is conflicting data on this, particularly in diverse populations.
As these authors note in their paper: “A link between AF and subsequent dementia has been observed in some but not all prospective studies.”
For example, research (HeartRhythm, 2010), using the Intermountain Heart Collaborative Study database, looked at 37 ,025 patients. In this study, AF was associated with all dementia types. A European study of 6,514 community‐based people, (JMA Neurology, 2015), found that prevalent and incident AF was significantly associated with dementia. However, in the Women’s Health Initiative Memory Study (JAHA, 2013), no association between AF and dementia was observed.
“Differences in study populations and methodology may explain these inconsistent findings, such as smaller sample size, shorter follow‐up periods, residual confounding, and inclusion of only specific subpopulations (eg, older or European people),” this team writes.
They attempted to clarify this association through a study of all adults from two health care delivery systems between 2010 and 2017 and performed a 1:1 match of incident AF: no AF by age at index date, sex, estimated glomerular filtration rate category, and study site. Whether the patients developed dementia was determined through previously validated diagnosis codes.
Among approximately 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.
In effect, 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 rate translates to 279 per 10,000 and 204 per 10,000.
The authors note that these data have several possible implications: “While the association of incident AF with dementia was modest overall, it was stronger in healthier and younger individuals and was observed even with a shorter follow‐up time compared with previous studies.”
