Changes of White Matter Integrity and Structural Network Topology in Carotid Stenosis Patients with Vascular Cognitive Impairment

Abstract

Abstract Background Patients with carotid artery stenosis (CAS) may have varying degrees of cognitive decline. Some patients have severe cognitive impairment fulfilling the diagnostic criteria for vascular cognitive impairment (VCI), and the underlying mechanisms of this phenomenon remain uncertain. We aim to investigate the reasons in terms of microstructural changes of white matter and alterations in structural network topology in CAS patients with VCI. Methods We included 38 unilateral CAS patients, 28 of whom were diagnosed with VCI. Each patient underwent magnetic resonance imaging scans and cognitive assessment. The microstructural integrity of white matter assessed by diffusion tensor imaging and structural network topology was jointly investigated. Correlation analyses were also performed between the structural metrics and general cognitive function. Results Decreased fractional anisotropy of white matter fibers including bilateral anterior thalamic radiations, bilateral inferior fronto-occipital fasciculi, forceps major and forceps minor (P < 0.05, Bonferroni corrected) were observed in patients with VCI. Both groups showed small-world topology. The global efficiency and local efficiency of VCI group were decreased, while the small worldness and the characteristic path length increased compared with that of the non-VCI group (P < 0.05). The integrity of forceps minor, left anterior thalamic radiations and bilateral inferior fronto-occipital fasciculi were associated with general cognition (P < 0.05). Conclusions Damage to white matter fibers in the frontal lobe and changes in the topological properties of structural networks were the underlying mechanisms of cognitive function deterioration in patients with CAS. The integrity of Fmin, left ATR, and bilateral IFOF may serve as early markers of VCI for CAS patients.