Effects of carotid artery stenting on cognitive function in patients with mild cognitive impairment and carotid stenosis

Carotid stenosis is known to be an independent risk factor in the transformation process of mild cognitive impairment (MCI) to dementia and is treated by carotid artery stenting (CAS); however, the effects of CAS on cognitive function are unclear. In this study, 240 patients were prospectively assigned to a CAS or control group according to patient preference and underwent detailed neuropsychological examinations (NPEs) before and 6 months after treatment. Cerebral perfusion was assessed with computed tomography perfusion (CTP). Among the 240 patients included in the study, 208 patients completed NPEs at baseline and 6 months after therapy. The patients in the two groups did not differ with regard to baseline characteristics, educational level, vascular risk factors (VRFs) and NPEs prior to therapy. Significant improvements in the Mini-Mental State Examination (MMSE; before, 24.6 +/- 1.7 vs. after, 24.8 +/- 1.9; P=0.016), Montreal Cognitive Assessment (MOCA; before, 23.7 +/- 1.7 vs. after, 24.1 +/- 2.0; P=0.006), Fuld Object Memory Evaluation (FOME; before, 13.8 +/- 2.2 vs. after, 14.0 +/- 2.3; P=0.031) and Wechsler Adult Intelligence Scale-digital span (WAIS-DS; before, 6.7 +/- 2.1 vs. after, 6.9 +/- 2.3; P=0.040) were observed in the CAS group; however, improvements were not observed in the control group. Of the 84 patients in the CAS group who received CTP follow-up, 72 (86%) presented improvements in ipsilateral brain perfusion 6 months after the procedure; however, no improvement was observed in the control group. Close correlations were identified between the change in perfusion and the change in MMSE (r=0.575) and MOCA (r=0.574). CAS improves global cognitive function in patients with carotid stenosis and MCI and the improvement of cognition is closely related to the improvement of cerebral perfusion.