Atrial fibrillation diagnosed in midlife is linked to a 21% increased risk of dementia at any age and a 36% higher risk of early-onset dementia, according to new [research](https://www.eurekalert.org/news-releases/1078453?) presented at a European cardiology conference.
Those findings matter most for adults aged 45 to 65 years and less so for those aged more than 70 years.
In this large Spanish study, researchers followed more than 2.5 million people for 13 years. They found that among younger to middle-aged patients (aged 45 to 50), those with AFib were more than three times more likely to develop dementia than those without it. For people aged more than 70 years, however, the researchers found no connection between AFib and dementia.
The study tracked individuals who were at least 45 years old in 2007 and had no prior diagnosis of [dementia](https://www.mcknights.com/news/studies-tie-socioeconomic-factors-to-dementia-diagnosis-timing-overall-cognitive-health/). At the start, about 3.25% of participants (almost 80,000 people) already had received diagnoses of AFib.
The link between AFib and dementia remained even after removing patients with a history of stroke from the analysis. When the researchers excluded stroke cases, AFib still was associated with a 23% increased risk of dementia in those in whom AFib had been diagnosed before age 70 and a 52% increased risk of early-onset dementia (diagnosed before 65).
“Atrial fibrillation seems to have a greater impact in younger patients, where it could be one of the main factors contributing to cognitive decline,” the researchers explained. They believe several mechanisms might be involved, including tiny undetected strokes, changes in blood flow to the brain, and inflammation.“The study demonstrates a significant and strong association in younger patients between two pathologies — atrial fibrillation and dementia — that are among the major health challenges of the 21st century,” concluded the study team, led by Julián Rodríguez García, MD, PhD, of the Electrophysiology and Arrhythmia Department at Bellvitge University Hospital in Barcelona. “We should now investigate whether early detection strategies and aggressive management of atrial fibrillation in younger patients can help reduce the risk of dementia and change the natural course of the disease.”