AFib and Risk for Dementia: Early Onset May Impair Cognitive Function

Adults with atrial fibrillation (AFib) who are diagnosed before age 65 have an elevated risk of developing dementia, according to study findings published in JAMA.

Epidemiological evidence has suggested a link between AFib and dementia. Researchers have also noted risk factors they have in common, such as obesity and diabetes; and have proposed causal mechanisms that might link AFib to dementia. However, it has not been directly studied whether age of AFib onset is associated with the risk of developing dementia.

For the current study, the researchers looked at data from the UK Biobank, collected between 2006 and 2010. They studied 433,746 participants (55% women) to test the association between AFib and incident dementia, without regard to age of AFib onset. Following, the researchers analyzed data for 30,600 participants who reported AFib and the age of onset. After categorizing those participants by age at onset (younger than 65, 65–74, and 75 and older), they tested this risk association within each age group, for all-cause, Alzheimer disease (AD) and vascular dementia.

The researchers repeated this analysis using propensity score matching to compare these age groups in a 1:2 ratio with 61,200 participants without AFib. All analyses excluded participants who reported dementia or stroke history at baseline, or who developed dementia before AFib onset.

Over a median 12.6 years of follow-up, a total of 5898 participants developed dementia (2546 with AD and 1211 with vascular dementia), and 1031 had AFib.

Participants with AFib were more likely to develop all-cause (adjusted hazard ratio [aHR], 1.42; 95% CI, 1.32–1.52; P <.001) and vascular (aHR, 2.06; 95% CI, 1.80–2.36; P <.001) dementia, but not AD. These participants tended to be older, White, men, and relatively less educated than the group without AFib; and were more likely to have diabetes and hypertension, and require statin medication.

The researchers then adjusted for these and other health-related variables.

When using propensity score matching, multivariate Cox regression analysis showed that compared with participants with AFib onset between ages 65 and 74, those with AFib onset before age 65 were more likely to develop all-cause dementia (aHR, 1.82; 95% CI, 1.54–2.15; P <.001).

In turn, compared with participants with AFib onset after age 75, those in the intermediate-age group had a higher risk for all-cause dementia (aHR, 1.47; 95% CI, 1.31–1.65; P <.001). These trends were replicated for both AD and vascular dementia.

The researchers’ findings highlighted that AFib was associated with an elevated risk for subsequent vascular, but not AD. From this, they suggested that AFib may more strongly influence the neuropathology of vascular dementia.

Study limitations included the its mostly White population, differences in baseline characteristics between groups, and that fact that information on any AFib treatment received was not considered.

“The quantitative manifestation of the association between AF [AFib] onset age and incident dementia highlights the importance of monitoring cognitive function among AF patients, especially those younger than 65 years at diagnosis,” the researchers concluded.