Carotid interventions improve cognitive function in patients with severe atherosclerotic carotid disease
Wei Zhou1, Yazan Ashouri1, Devin P. Murphy3, Ying-Hui Chou2, Chiu-Hsieh Hsu4, Theodore Trouard3
1Surgery, University of Arizona, Tucson, Arizona, United States, 2Psychology, University of Arizona, Tucson, Arizona, United States, 3Biomedical Engineer, University of Arizona, Tucson, Arizona, United States, 4Public Health, University of Arizona, Tucson, Arizona, United States
Objectives: Carotid occlusive disease is reported to impact cognitive function. Reduced cerebral blood flow is considered a culprit in carotid disease-related cognitive impairment. However, the association is not consistent and the cognitive effects of carotid interventions is largely debatable. We sought to understand the effects of carotid interventions on cognitive functions and the relationship between baseline cerebral blood flow (CBF) and cognitive functions in a well-defined cohort of patients with severe extracranial carotid disease.
Methods: 180 patients undergoing carotid interventions were prospectively recruited from two academic institutions. All patients received cognitive testing and brain MRI preop. For cognitive testing, raw scores were normalized against age, education, and standard scores as appropriate. The domain-specific normalized scores were derived using principal component analysis. Episodic memory measured by Ray Auditory Verbal Learning Test (RAVLT) was the primary outcome measure. Pseudo-continuous arterial spin labelling MRI sequence were used to derive baseline CBF. Univariate and multiple linear regression models were fitted to evaluate predictors of each cognitive domain.
Results: Most subjects were males (96%) with a mean age of 70 years. 51% of the cohort were symptomatic. Most subjects were smokers (78%) and hypertensive (86%). Diabetes was prevalent (39%). 140 subjects were included in our analysis. After normalizing against age-matched Mayo’s older Americans normative studies and group means, RAVLT Z scores for sum of the trials were generated. The average preop Z score was lower (Z=-0.79, SD 1.3, CI: -1 to -0.53) ) than age-adjusted norm, suggesting impaired baseline episodic memory. We observed a significant improvement in memory scores post-carotid interventions at 1 month and 6 months compared to the preop baseline. The score return to, but slightly higher than the baseline at 12 months. We also observed improvement in Mini-Mental State Exam postop.
Our regression model analyses showed that baseline CBF (p=0.035), prior stroke (p<0.01), and diabetes (p<0.01) were independently associated with performance on the Trail Making test, an executive function measure. Baseline CBF was also associated with test scores on the Stroop test, another executive function measure, in a simple linear regression (P=0.013), and the trend persisted, albeit nonsignificant, (P=0.056) in the multiple linear regression model. Other significant variables independently associated with a Stroop test were age, renal insufficiency, and prior stroke.
Conclusion: This prospective study underscored that carotid interventions improved memory function in patients with severe carotid occlusive disease and an independent association between baseline CBF and executive function. Inconsistency in the literature on the cognitive impacts of carotid interventions may be due to diverse cognitive measures and patient-related co-morbidities.
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