Background and Purpose: Cerebral small vessel disease, as a potential mechanism underlying the association between atrial fibrillation (AF) and dementia, remains poorly investigated. In this cohort study, we sought to examine the association between AF and cerebral small vessel disease markers among older adults.

Methods: Data on 336 participants (age >= 60 years, mean 70.2 years; 60.2% women) free of dementia, disability, and cerebral infarcts were derived from the population-based Swedish National Study on Aging and Care in Kungsholmen. Structural brain magnetic resonance imaging examinations were performed at baseline (2001-2004) and follow-ups (2004-2007 and 2007-2010). Magnetic resonance imaging markers of cerebral small vessel disease included perivascular spaces, lacunes, and volumes of white matter hyperintensities, lateral ventricles, and total brain tissue. AF was assessed at baseline and follow-ups through clinical examinations, electrocardiogram, and medical records. Data were analyzed using linear mixed-effects models.

Results: At baseline, 18 persons (5.4%) were identified to have prevalent AF and 17 (5.6%) developed incident AF over the 6-year follow-up. After multivariable adjustment, AF was significantly associated with a faster annual increase in white matter hyperintensities volume (beta coefficient=0.45 [95% CI, 0.04-0.86]) and lateral ventricular volume (0.58 [0.13-1.02]). There was no significant association of AF with annual changes in perivascular spaces number (beta coefficient=0.53 [95% CI, -0.27 to 1.34]) or lacune number (-0.01 [-0.07 to 0.05]).

Conclusions: Independent of cerebral infarcts, AF is associated with accelerated progression of white matter lesions and ventricular enlargement among older adults.