Asymptomatic Carotid Disease and Cognitive Impairment: What Is the Evidence?

Abstract

The development of cognitive dysfunction and dementia is a complex, multifactorial process. One of the contributors to various types of cognitive dysfunction is carotid atherosclerosis which can frequently be seen in asymptomatic individuals. There are a number of different manifestations of asymptomatic carotid atherosclerosis including arterial stiffness, carotid intima-media thickening, flow-limiting stenosis, and complex, atherosclerotic plaque. Each of these forms of atherosclerosis may contribute to cerebral parenchymal damage, contributing to cognitive dysfunction. In this review article, we will discuss each of these forms of carotid atherosclerosis, present the potential mechanistic underpinnings behind an association, and then review the scientific evidence supporting potential associations to cognitive dysfunction and dementia.

Association between Extracranial Carotid Artery Plaque and Cognitive Dysfunction: A Systematic Review and Meta-Analysis

“…vascular risk factors, specifically carotid artery atherosclerosis, may play an important role in the development of cognitive decline and dementia [3][4][5]. There is evidence of an association between various expressions of carotid atherosclerosis and cognitive dysfunction including increased carotid intima media thickness, carotid stiffness, and carotid stenosis [6,7]. Another specific expression of carotid atherosclerosis is the presence of carotid plaque, which usually indicates more advanced atherosclerosis than carotid intima thickness or increased carotid stiffness.…”

“…An association between carotid plaque and cognition could potentially be mediated by thromboembolic infarcts leading to cerebral parenchymal damage, which in turn leads to cognitive impairment. Other forms of carotid atherosclerosis may also mediate the association with cognition via other potential mechanisms including cerebral hypoperfusion from flow-limitation, decreased amyloid-β clearance from arterial stiffening, altered flow dynamics leading to blood-brain barrier permeability issues, or shared inflammatory pathways [7].…”

Editorial for “Altered Callosal Morphology and Connectivity in Asymptomatic Carotid Stenosis”

“…3 On the contrary, little is known about the impact of asymptomatic carotid stenosis (ACS) on cerebral hemodynamics and brain parenchymal status, although there is evidence that patients with asymptomatic carotid stenosis are at increased risk of developing a progressive decline in their cognitive function. 4,5 In this issue of JMRI, the manuscript "Altered callosal morphology and connectivity in asymptomatic carotid stenosis" 6 aimed to study the correlation between the morphology and connectivity of the corpus callosum (CC) with cognitive decline and silent lesion burden in ACS. In a cohort of 33 patients with unilateral severe (≥70%), albeit asymptomatic, carotid artery stenosis, a structural MRI and multidomain cognitive data were obtained.…”

“…Furthermore, a combined assessment of CC morphology and connectivity with hemodynamic investigation at brain tissue level correlated with cognitive status appraisal in future studies could add important evidence to the potential link between asymptomatic carotid artery stenosis and cognitive impairment and may reverse the current formal guidance not to perform routine screening for extracranial plaque in asymptomatic individuals. 4…”

“…In patients with symptomatic high‐grade extracranial ICA stenosis, the predominant mechanism is considered thromboembolic 3 ; however, it has been suggested that marginal flow and impaired cerebrovascular reserve may enhance the thromboembolic risk due to impaired clearance of emboli 3 . On the contrary, little is known about the impact of asymptomatic carotid stenosis (ACS) on cerebral hemodynamics and brain parenchymal status, although there is evidence that patients with asymptomatic carotid stenosis are at increased risk of developing a progressive decline in their cognitive function 4,5 …”