title: Impairments in cognitive function and brain connectivity in severe asymptomatic carotid stenosis.
abstract: OBJECTIVE
  Severe asymptomatic carotid stenosis has been associated with cognitive impairment, but it is unknown whether this association is attributable to effects on brain connectivity. We present cognitive network abnormalities in a group of patients at a presymptomatic stage.
  
  
  METHODS
  Seventeen patients with ≥ 70% asymptomatic stenosis of unilateral internal carotid artery were compared with 26 healthy controls utilizing a comprehensive neuropsychological battery, the dizziness handicap inventory, and multimodality neuroimaging including diffusion tensor imaging and resting-state functional connectivity magnetic resonance imaging. Longitudinally, assessments were completed in a subgroup of 10 patients at 3 months after carotid artery stenting.
  
  
  RESULTS
  Compared with the healthy controls, the patients had worse dizziness scores, poorer memory, complex visuo-spatial performances, and lower whole-brain mean fractional anisotropy. The Scheltens scores of leukoaraiosis/infarction were not different between groups. Their seed-based functional connectivity magnetic resonance imaging showed marked decrements of interhemispheric and intrahemispheric, ipsilaterally to carotid stenosis, functional connectivity in the frontoparietal network. In the default mode network, the intrahemispheric functional connectivity was bilaterally impaired. Importantly, the disrupted mean fractional anisotropy in the patients significantly correlated with the attention and verbal memory functions. After successful carotid artery stenting, small but measurable increments of the mean fractional anisotropy and little functional connectivity in the default mode network ipsilateral-to-carotid artery stenting were noted.
  
  
  CONCLUSIONS
  We identified for the first time distinct patterns of network disruption that correlate with cognitive fragility in patients with asymptomatic carotid stenosis. Brain connectivity may provide early and useful biomarkers for brain ischemia and reperfusion.
authors.affiliation: Institute of Brain Science, School of Medicine, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Hsien-Lin
authors.initials: HL
authors.lastname: Cheng
authors.forename: Chun-Jen
authors.initials: CJ
authors.lastname: Lin
authors.forename: Bing-Wen
authors.initials: BW
authors.lastname: Soong
authors.forename: Pei-Ning
authors.initials: PN
authors.lastname: Wang
authors.forename: Feng-Chi
authors.initials: FC
authors.lastname: Chang
authors.forename: Yu-Te
authors.initials: YT
authors.lastname: Wu
authors.forename: Kun-Hsien
authors.initials: KH
authors.lastname: Chou
authors.forename: Ching-Po
authors.initials: CP
authors.lastname: Lin
authors.forename: Pei-Chi
authors.initials: PC
authors.lastname: Tu
authors.forename: I-Hui
authors.initials: IH
authors.lastname: Lee
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D016880:Anisotropy; D001931:Brain Mapping; D016893:Carotid Stenosis / Q000453:epidemiology / Q000473:pathology / Q000503:physiopathology*; D016022:Case-Control Studies; D003072:Cognition Disorders / Q000453:epidemiology / Q000473:pathology / Q000503:physiopathology*; D015897:Comorbidity; D063132:Connectome; D004244:Dizziness / Q000453:epidemiology; D005260:Female; D059907:Functional Neuroimaging; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008569:Memory Disorders / Q000453:epidemiology; D008875:Middle Aged; D009415:Nerve Net / Q000473:pathology / Q000503:physiopathology*; D009483:Neuropsychological Tests; D012189:Retrospective Studies; D012720:Severity of Illness Index