Default Mode Network Disruption in Stroke-Free Patients with Atrial Fibrillation

Abstract

Background: Atrial fibrillation (AF) is a widely accepted risk for causing stroke. However, recent studies show AF as a risk factor for dementia, even without causing stroke. The mechanisms by which dementia develops in stroke-free patients with AF are still poorly understood and the association of AF with abnormal function of brain networks activities, such as the default mode network (DMN), has not been previously studied. We aimed to determine whether, in the absence of stroke and dementia, patients with AF have abnormal resting-state brain networks compared to controls without AF. Methods: Twenty-one stroke-free patients with AF and 21 age- and sex-matched controls without AF underwent brain functional magnetic resonance imaging acquired at a 3.0 Tesla scanner. During the exam, the subjects were instructed to lie still with eyes closed. At first-level analysis, connectivity of the DMN was obtained for all subjects. Second-level analysis compared the DMN connectivity between AF patients and controls with a general linear model (two-sample t test, p < 0.05, False Discovery Rate corrected, minimum of 50 contiguous voxels). Results: Patients with AF compared with controls showed decreased connectivity in regions of the DMN including the frontal lobe (left medial frontal gyrus, left superior frontal gyrus and anterior cingulate), left angular gyrus, and bilateral precuneus. Conclusions: Stroke-free patients with AF have evidence of abnormal DMN connectivity. This study adds evidence to the occurrence of cerebral dysfunction in patients with AF.

Brain Imaging Changes and Related Risk Factors of Cognitive Impairment in Patients With Heart Failure

“…Junejo et al ( 139 ) demonstrated by using specific experiments that patients with AF exhibited impaired neurovascular coupling responses to visual stimulation, while the automatic regulation function of the brain was weakened. Silva et al ( 140 ) demonstrated that the patients with AF exhibited decreased connectivity in regions of the default mode network (DMN) including the frontal lobe (left superior frontal gyrus and left medial frontal gyrus), bilateral precuneus, and left angular gyrus.…”

From Biological Rhythms to the Default Mode Network: What Lies beneath the Tip of the Iceberg of Mind?

“…Increased DMN integrity and activation in the anterior module is associated with depressive rumination and anxiety [65] [66]. Other somatic illnesses that result in altered DMN function include obesity [67], sleep apnea [68], respiratory disorders [69], gastrointestinal disorders [70], cardiac/vascular disorders [71], and others [72]. In our perspective, the abnormal DMN state of these disorders can be explained by the altered non-neural processes of the body which then influence the brain.…”

Disruption of Resting-State Functional Connectivity in Acute Ischemic Stroke: Comparisons Between Right and Left Hemispheric Insults

“…The Neurovascular Protocol includes volumetric/structural acquisitions in T1, T2, FLAIR, SWI, DWI, ADC, and Magnetic Resonance Angiography (MRA) with "time of ight" (TOF). The parameters were: threedimensional T1 weighted turbo eld echo images (WI) (180 slices, 1 mm 3 isotropic voxels, acquired on the sagittal plane, 1mm thickness, ip angle = 8 o , TR = 7.1ms, echo time (TE) 3.2 milliseconds, matrix = 240 × 240, eld of view (FOV) = 240 × 240); T2 weighted image (1.5 mm 3 isotropic voxels, 180 axial slices, no gap, TR = 1.8ms, TE = 340ms, FOV = 230 × 230mm 2 ); uid-attenuated inversion recovery (FLAIR) image (voxel size = 1.2 × 1.2 × 0.6mm 3 , FOV = 250 × 250 mm 2 , TE = 276ms, TR = 4.8ms, TI = 1.650ms) 42 .…”