Reduced neuropsychological test performance in asymptomatic carotid stenosis: The Tromso Study

Asymptomatic Carotid Artery Stenosis, Cognitive Function, and the Impact of Carotid Revascularization: A Narrative Review

BACKGROUND

The association between asymptomatic carotid artery stenosis and impaired cognition, and the cognitive changes after revascularization remain active areas of interest in the field of carotid disease. This narrative review focuses on the association between carotid artery atherosclerosis and impaired cognitive function, proposed mechanisms, and the effects of carotid revascularization on cognition.

METHODS

A critical review of the literature to identify studies evaluating carotid artery stenosis, cognition, and carotid revascularization was performed using PubMed to query the MEDLINE database through March 2023.

RESULTS

Many studies demonstrate a link between carotid disease and cognitive impairment but direct evidence is lacking. Revascularization may offer cognitive benefits but the effect is likely subtle and affected by the choice of revascularization procedure.

CONCLUSIONS

Integrating cognitive outcomes into ongoing randomized controlled trials such as the nested CREST-H arm of the CREST-2 trial hold promise for offering new insight into the role of carotid artery stenosis and carotid revascularization on cognition.

Neurofibrillary tangles predict dementia in patients with carotid stenosis

OBJECTIVE

There is growing appreciation that extracranial carotid atherosclerotic disease (ECAD) is associated with increased dementia risk. Despite this, clinical management of ECAD does not involve evaluation for cognitive outcomes or risk stratification for dementia. One impediment to studying and improving clinical care for this cohort (roughly 10% of adults aged >60 years) is that factors to identify patients with ECAD at risk for dementia are not known.

METHODS

Our prospective clinicopathologic study, the Arizona Study of Aging and Neurodegenerative Disorders study, evaluated clinical and histopathologic factors for dementia in subjects with ECAD. The primary outcome (dementia) was defined as a composite of Alzheimer's disease and/or vascular dementia based on a clinical/neuropathologic diagnosis. Of 1234 subjects, those with dementia other than Alzheimer's disease and/or vascular dementia were excluded; there remained 111 subjects with ECAD to be evaluated. Logistic regression analysis was performed to examine the association of key risk factors for dementia including age, sex, cardiovascular risk factors, apolipoprotein E4 (APOE4) genetic status, and dementia biomarkers. A precision recall curve was also generated to evaluate the diagnostic accuracy of dementia prediction models.

RESULTS

Individuals with dementia compared with those without had significantly increased levels of stroke, APOE4 genotype, and dementia biomarkers, neurofibrillary tangles (NFTs), and amyloid plaques. Models of multiple combined risk factors were little or no better than NFTs alone, which showed a 96.9% positive predictive value at an NFT threshold of 10.

CONCLUSIONS

Although we hypothesized that a combination of clinical and histopathologic biomarkers would result in the strongest predictive model for dementia, we found that NFTs alone had the highest association and positive predictive value for dementia risk in patients with ECAD. As blood-based assays for NFT quantification become more clinically reliable and available, these data support the possibility that NFT quantification may help identify patients with ECAD at increased risk for dementia.

Temporal changes and implications of diffusion tensor imaging metrics and cerebral white matter volume in patients undergoing carotid endarterectomy - a prospective study

AIMS

To test utility of diffusion MRI-derived indices in carotid endarterectomy (CEA), change of diffusion tensor imaging (DTI) metrics, cerebral white matter (WM) volumes were evaluated and predictors of overall mortality determined.

METHODS

Prospectively enrolled participants had preoperative, immediate and late postoperative DTI after CEA. WM volumes, DTI metrics (fractional anisotropy, FA; axial, radial, mean diffusivities; AD, RD, MD, respectively) were calculated for the index/contralateral hemispheres at all time points. Temporal changes, predictors of log2-transformed WM volumes, DTI values were analyzed using linear mixed model. Uni- and multivariable Cox proportional hazards models were used to identify predictors of mortality.

RESULTS

60 subjects (57% male, 69.5 ± 7.2years) were included. Significantly increased AD and MD was observed in both hemispheres comparing the preoperative and immediate postoperative DTI metrics (index AD: β = 0.02 [95%CI:0.01,0.02], p < 0.001; index MD: β = 0.02 [95%CI:0.01,0.03], p < 0.001; contralateral AD: β = 0.01 [95%CI:0.01,0.02], p = 0.001; contralateral MD: β = 0.02 [95%CI:0.01,0.03], p = 0.003). The index MD decreased (β = 0.01 [95%CI:0.01,0.001], p = 0.04), bilateral WM volumes (index WM: β = 0.04 [95%CI:0.02,0.07], p < 0.001; contralateral WM: β = 0.05 [95%CI:0.03,0.07], p < 0.001) decreased significantly between the immediate and late postoperative scans. Postoperative contralateral FA correlated significantly with lower mortality (HR = 0.001 [95%CI:0.001,0.19], p = 0.02); postoperative contralateral RD (HR = 3.74 × 104 [95%CI:1.62,8.60 × 108], p = 0.04) and MD (HR = 1.19 × 105 [95%CI:1.03,1.37 × 1010], p = 0.049) were significant predictors of mortality.

CONCLUSION

The increase of various DTI metrics from pre-to-postoperative may be indicative of microstructural deterioration following CEA. Temporal changes between the immediate and late postoperative scans suggest, however, reversal of detrimental WM changes and clearance of presumed subclinical WM edema. Our results also imply, that preserved cerebral properties are protective after CEA.

Cognitive impairment in asymptomatic carotid artery stenosis is associated with abnormal segments in the Circle of Willis

OBJECTIVE

Our group has previously demonstrated that patients with asymptomatic carotid artery stenosis (ACAS) demonstrate cognitive impairment. One proposed mechanism for cognitive impairment in patients with ACAS is cerebral hypoperfusion due to flow-restriction. We tested whether the combination of a high-grade carotid stenosis and inadequate cross-collateralization in the Circle of Willis (CoW) resulted in worsened cognitive impairment.

METHODS

Twenty-four patients with high-grade (≥70% diameter-reducing) ACAS underwent carotid duplex ultrasound, cognitive assessment, and 3D time-of-flight magnetic resonance angiography. The cognitive battery consisted of nine neuropsychological tests assessing four cognitive domains: learning and recall, attention and working memory, motor and processing speed, and executive function. Raw cognitive scores were converted into standardized T-scores. A structured interpretation of the magnetic resonance angiography images was performed with each segment of the CoW categorized as being either normal or abnormal. Abnormal segments of the CoW were defined as segments characterized as narrowed or occluded due to congenital aplasia or hypoplasia, or acquired atherosclerotic stenosis or occlusion. Linear regression was used to estimate the association between the number of abnormal segments in the CoW, and individual cognitive domain scores. Significance was set to P < .05.

RESULTS

The mean age of the patients was 66.1 ± 9.6 years, and 79.2% (n = 19) were male. A significant negative association was found between the number of abnormal segments in the CoW and cognitive scores in the learning and recall (β = -6.5; P = .01), and attention and working memory (β = -7.0; P = .02) domains. There was a trend suggesting a negative association in the motor and processing speed (β = -2.4; P = .35) and executive function (β = -4.5; P = .06) domains that did not reach significance.

CONCLUSIONS

In patients with high-grade ACAS, the concomitant presence of increasing occlusive disease in the CoW correlates with worse cognitive function. This association was significant in the learning and recall and attention and working memory domains. Although motor and processing speed and executive function also declined numerically with increasing abnormal segments in the CoW, the relationship was not significant. Since flow restriction at a carotid stenosis compounded by inadequate collateral compensation across a diseased CoW worsens cerebral perfusion, our findings support the hypothesis that cerebral hypoperfusion underlies the observed cognitive impairment in patients with ACAS.

An analysis of the recommendations of the 2022 Society for Vascular Surgery clinical practice guidelines for patients with asymptomatic carotid stenosis

OBJECTIVE

Patients with asymptomatic carotid artery stenosis currently account for the majority of carotid interventions performed in the United States; therefore, the following article will review the 2022 Society for Vascular Surgery (SVS) clinical practice guidelines perspective in treating patient with asymptomatic carotid stenosis.

METHODS

A systemic review and meta-analysis were conducted by the evidence practice center of the Mayo Clinic using a specified population, intervention, comparison, outcome (PICO) framework.

RESULTS

Based on published randomized trials and related supporting evidence, the following were noted: the SVS recommends that patients with asymptomatic ≥70% stenosis can be considered for carotid endarterectomy (CEA), transcarotid artery revascularization (TCAR), or transfemoral carotid artery stenting (TFCAS) for the reduction of long-term risk of stroke, provided the patient has a life expectancy of 3 to 5 years with risk of perioperative stroke and death not exceeding 3%. The type of carotid intervention should be based on the presence or absence of high-risk criteria for each specified intervention. Data from CREST, ACT, and the Vascular Quality Initiative suggest that certain properly selected asymptomatic patients can be treated with carotid stenting with equivalent outcome to CEA in the hands of experienced interventionalists. The institutions and operator performing carotid stenting must exhibit expertise sufficient to meet the established American Heart Association guidelines for treatment of patient with asymptomatic carotid stenosis (ie, combined stroke/death rate of less than 3%).

CONCLUSIONS

SVS recommends that low surgical risk patients with asymptomatic carotid stenosis of ≥70% to be treated with CEA with best medical therapy over medical therapy alone for the long-term prevention of stroke/death (GRADE 1B). Carotid intervention should also be based on the presence or absence of high-risk criteria for each specified intervention (ie, CEA, TCAR, and TFCAS).

Cognitive effects of carotid revascularization in octogenarians

BACKGROUND

Cognitive impairment is the epitome of cerebrovascular diseases, causing a significant economic burden on our health care system. Growing evidence has indicated the benefits of carotid interventions in patients with severe carotid atherosclerosis. However, the neurocognitive outcome of carotid revascularization in octogenarians is not clearly understood. We aim to evaluate postintervention cognitive changes in seniors older than 80 years.

METHODS

We prospectively recruited 170 patients undergoing carotid interventions. Neurocognitive testing was performed preoperatively and at 1, 6, and 12 months postoperatively. Episodic memory was assessed with Rey's Auditory Verbal Learning Test. Other executive functions and language measures were also evaluated at individual time points. Raw test scores were converted to z-scores or scaled scores adjusted for age and education. The sample was divided into 2 groups based on age: octogenarian (≥80 years) and nonoctogenarian (<80 years old). Postoperative cognitive scores were compared to baseline within each subcohort.

RESULTS

A total of 23 subjects (13%) were octogenarians, and 147 (87%) were younger than 80 years. Younger patients demonstrated significant cognitive improvements up to 12 months postop compared to the baseline. However, octogenarians exhibited a lack of improvement in verbal memory, measures of executive function, and language at all 3 postintervention time points.

CONCLUSION

Carotid interventions improve cognitive functions in younger patients with carotid occlusive atherosclerosis. However, no cognitive benefits were seen in male seniors older than 80 years. Further investigations are warranted to better understand the postinterventional cognitive changes in octogenarians.

The association of diffusion tensor MRI measures of normal appearing white matter and cognition

Objective

Median and peak height of fractional anisotropy (FA) and mean diffusivity (MD) are diffusion tensor imaging (DTI) markers used to quantify white matter microstructure changes. We examine the association of DTI histogram-derived measures in global normal appearing white matter (NAWM) and cognitive decline in patients with normal cognition and cognitive impairment no dementia from a memory clinic in Singapore.

Methods

A total of 252 patients (mean age: 71.1 ± 7.6 years, 53.2% women) were included. All patients underwent clinical assessments, a brain MRI scan at baseline, and neuropsychological assessments annually for 2 years. DTI scans were processed to obtain MD and FA histogram-derived measures. The National Institute of Neurological Disorders and Stroke and the Canadian Stroke Network harmonization neuropsychological battery were used to assess cognitive function. Linear regression models with generalised estimating equation (GEE) and logistic regression models were used to examine the association between DTI histogram measures and cognitive decline.

Results

When compared to baseline, MD and FA measures at Year 2 were associated with an accelerated worsening in global cognition (all p for interaction <0.001; Year 0 vs 2, MD median: -0.29 (95%CI: -0.49, -0.09) vs -0.45 (95%CI: -0.65,-0.25); MD peak height: 0.22 (95%CI: 0.07, 0.37) vs 0.37 (95%CI: 0.21, 0.53); FA median: 0.11 (95%CI: -0.05, 0.26) vs 0.22 (95%CI: 0.07, 0.37); FA peak height: -0.14 (95%CI: -0.28, 0.00) vs -0.24 (95%CI: -0.38, -0.10);). Similar findings were observed for executive function and visuomotor speed while only MD measures predicted worsening in memory domain.

Interpretation

This study shows that DTI histogram measures are associated with accelerated cognitive decline suggesting the utility of DTI as a pre-clinical marker in predicting the worsening of cognition in clinical trials.

Ambient RNAs removal of cortex-specific snRNA-seq reveals Apoe+ microglia/macrophage after deeper cerebral hypoperfusion in mice

BACKGROUND

Ambient RNAs contamination in single-nuclei RNA sequencing (snRNA-seq) is a challenging problem, but the consequences of ambient RNAs contamination of damaged and/or diseased tissues are poorly understood. Cognitive impairments and white/gray matter injuries are characteristic of deeper cerebral hypoperfusion mouse models induced by bilateral carotid artery stenosis (BCAS), but the molecular mechanisms still need to be further explored. More importantly, the BCAS mice can also offer an excellent model to examine the signatures of ambient RNAs contamination in damaged tissues when performing snRNA-seq.

METHODS

After the sham and BCAS mice were established, cortex-specific single-nuclei libraries were constructed. Single-nuclei transcriptomes were described informatically by the R package Seurat, and ambient RNA markers of were identified in each library. Then, after removing ambient RNAs in each sample using the in silico approaches, the combination of CellBender and subcluster cleaning, single-nuclei transcriptomes were reconstructed. Next, the comparison of ambient RNA contamination was performed using irGSEA analysis before and after the in silico approaches. Finally, further bioinformatic analyses were performed.

RESULTS

The ambient RNAs are more predominant in the BCAS group than the sham group. The contamination mainly originated from damaged neuronal nuclei, but could be reduced largely using the in silico approaches. The integrative analysis of cortex-specific snRNA-seq data and the published bulk transcriptome revealed that microglia and other immune cells were the primary effectors. In the sequential microglia/immune subgroups analysis, the subgroup of Apoe⁺ MG/Mac (microglia/macrophages) was identified. Interestingly, this subgroup mainly participated in the pathways of lipid metabolism, associated with the phagocytosis of cell debris.

CONCLUSIONS

Taken together, our current study unravels the features of ambient RNAs in snRNA-seq datasets under diseased conditions, and the in silico approaches can effectively eliminate the incorrected cell annotation and following misleading analysis. In the future, snRNA-seq data analysis should be carefully revisited, and ambient RNAs removal needs to be taken into consideration, especially for those diseased tissues. To our best knowledge, our study also offers the first cortex-specific snRNA-seq data of deeper cerebral hypoperfusion, which provides with novel therapeutic targets.

Carotid disease, cognition, and aging: time to redefine asymptomatic disease?

There is an increasing appreciation of the vascular contributions in the development of age-related cognitive impairment and dementia1,2. Identifying risk and maintaining cognitive health for successful aging is ever relevant in our aging population. Carotid disease, a well-established risk factor for stroke and often a harbinger of other vascular disease states, is also emerging as another vascular risk factor for age-related cognitive decline. When combined with vascular risk factors, the incidence of age-related carotid disease can be as high as 70%3,4. Historically, carotid disease has been dichotomized into two large groups in trial design, outcome measurements, and treatment decisions: symptomatic and asymptomatic carotid artery stenosis. The dichotomous distinction between asymptomatic and symptomatic carotid stenosis based on existing definitions may be limiting the care we are able to provide for patients classified as "asymptomatic" from their carotid disease. Medically, we now know that these patients should be treated with the same intensive medical therapy as those with "symptomatic" carotid disease. Emerging data also shows that hypoperfusion from asymptomatic disease may lead to significant cognitive impairment in the aging population, and it is plausible that most "age-related" cognitive changes may be reflective of vascular impairment and neurovascular dysfunction. While over the past 30 years medical, surgical, and radiological advances have pushed the field of neurovascular disease to significantly reduce the number of ischemic strokes, we are far from any meaningful interventions to prevent vascular cognitive impairment. In addition to including cognitive outcome measures, future studies of carotid disease will also benefit from including advanced neuroimaging modalities not currently utilized in standard clinical imaging protocols, such as perfusion imaging and/or functional connectivity mapping, which may provide novel data to better assess for hypoxic-ischemic changes and neurovascular dysfunction across diffuse cognitive networks. While current recommendations advise against widespread population screening for asymptomatic carotid stenosis, emerging evidence linking carotid stenosis to cognitive impairment prompts us to re-consider our approach for older patients with vascular risk factors who are at risk for cognitive decline.

Study of cognitive function in patients with severe asymptomatic carotid artery stenosis by a computerized neuropsychological assessment device

Background

Carotid stenosis can lead to stroke and cognitive impairment. Moreover, the cognitive function was assessed mostly by paper and pencil cognitive tests. This study aimed to evaluate the impact of severe asymptomatic carotid artery stenosis (SACAS) on cognitive function by a computerized neuropsychological assessment device (CNAD). The diagnostic value of screening SACAS of the CNAD was analyzed.

Methods

There were 48 patients with ≥70% asymptomatic carotid stenosis and 52 controls without carotid stenosis. Duplex ultrasound defined the degree of stenosis. The differences of cognitive function were analyzed between patients and controls. The relationship of scores of cognitive tests and age were analyzed in the linear regression equation. The diagnostic value of CNAD was evaluated by the receiver operating characteristic (ROC) curve.

Results

Stenosis and control subjects had no statistically significant differences in baseline characteristics. Stenosis patients had worse scores for Stroop color-word test (p = 0.002), one back test (p = 0.013), and identification test (p = 0.006) corresponding to attention and executive ability. The analysis of linear regression equation indicated that cognitive scores of stenosis patients declined faster with age, especially for digit span test, Stroop color-word test, one back test and identification test. In analysis of ROC curve, the Stroop color-word test (p = 0.002), one back test (p = 0.013), and identification test (p = 0.006), and comprehensive index of the three tests (p = 0.001) had the diagnostic value.

Conclusion

The CNAD has evaluation value and screening value for patients with cognitive impairment and SACAS. But it is necessary to update the CNAD and conduct a study with a bigger sample.

Nomogram to Predict Cognitive Impairment in Patients with Asymptomatic Middle Cerebral Artery Stenosis

Purpose

This study aims to investigate the characteristics and influencing factors of cognitive impairment in patients with asymptomatic middle cerebral artery stenosis (aMCAS) and to construct a nomogram to predict the risk of cognitive impairment in patients with aMCAS.

Patients and Methods

We collected 54 patients with aMCAS and 35 healthy controls to investigate the impaired cognitive domains and pathogenesis in patients with aMCAS. All patients underwent a cranial MRI, CT perfusion, transcranial Doppler ultrasound, blood tests, and a comprehensive neuropsychological evaluation. According to the MoCA score, patients were divided into cognitively normal and cognitively impaired groups. To construct the nomogram, we conducted univariate and multivariate logistic regression analyses to identify factors that affect cognitive function. And the performance of nomogram was evaluated by ROC curves, calibration curves, decision curve analysis (DCA), and clinical impact curve (CIC).

Results

In 54 patients with aMCAS, 24 patients presented with cognitive normal, and 30 patients presented with cognitive impairment. The results of multivariate logistic regression suggested that perfusion decompensation, middle cerebral artery mean flow velocity, and LDL-cholesterol levels were independent influencing factors of cognitive impairment. In the following step, a nomogram was constructed. The AUC of the nomogram is 0.862. Calibrating curves show good agreement between nomogram predictions and actual observations, while DCA and CIC show great clinical usefulness.

Conclusion

Patients with aMCAS have cognitive impairment in multiple cognitive domains, and impaired executive function was observed during the perfusion compensation period. Furthermore, a nomogram was constructed and validated to predict the risk of cognitive impairment in patients with aMCAS, which can help clinicians to identify at an early stage and improve the management of patients.

Abnormalities of hippocampus and frontal lobes in heart failure patients and animal models with cognitive impairment or depression: A systematic review

AIMS

This systematic review aimed to study the hippocampal and frontal changes of heart failure (HF) patients and HF animal models with cognitive impairment or depression.

METHODS

A systematic review of the literature was conducted independently by reviewers using PubMed, Web of Science, Embase, and the Cochrane Library databases.

RESULTS AND CONCLUSIONS

30 studies were included, involving 17 pieces of clinical research on HF patients and 13 studies of HF animal models. In HF patients, the hippocampal injuries were shown in the reduction of volume, CBF, glucose metabolism, and gray matter, which were mainly observed in the right hippocampus. The frontal damages were only in reduced gray matter and have no difference between the right and left sides. The included HF animal model studies were generalized and demonstrated the changes in inflammation and apoptosis, synaptic reduction, and neurotransmitter disorders in the hippocampus and frontal lobes. The results of HF animal model studies complemented the clinical observations by providing potential mechanistic explanations of the changes in the hippocampus and frontal lobes.

Neuropsychological tests and prediction of dementia in association with the degree of carotid stenosis

This study constitutes a cross sectional analysis of the association between cognitive impairment defined by neuropsychological tests and carotid stenosis. The main objective was to compare the results of the Mini-Mental State Examination (MMSE) and Addenbrooke's Cognitive Examination-Revised (ACE-R) with regard to the degree of carotid stenosis. The sample comprised 744 patients who underwent a carotid duplex ultrasound and cognitive function testing (by ACE-R and MMSE). A multivariable analysis of potential confounding factors was completed. The significance of the different number of positive (MMSE ≤ 27, ACE-R ≤ 88) and negative (MMSE ≥ 28, ACE-R ≥ 89) results of the neuropsychological tests was analysed with regard to the degree of carotid stenosis (50-99%). Neuropsychological test results were also compared between carotid stenosis of 50-69%, 70-89%, and 90-99%. For both the MMSE and ACE-R, a difference was observed between positive and negative test results when higher degrees of stenosis were present. However, for the ACE-R only, more severe stenosis (80-89%, 90-99%) was predominantly associated with positive test results (p-value < 0.017). The same dependence for ACE-R (although not statistically significant) was observed in the group of patients without an ischemic stroke (confounding factor). In the case of the MMSE and more severe stenosis, negative results predominated, regardless of the confounding factor. There were no statistically significant differences in test results between carotid stenosis of 50-69%, 70-89%, and 90-99%. The results suggest that for assessing the early risk of cognitive impairment in patients with carotid atherosclerosis, the ACE-R appears more suitable than the MMSE.

Effects of carotid artery stenting on cognitive impairment in patients with severe symptomatic carotid artery stenosis

The effect of carotid artery stenting and medication on improvement of cognitive function in patients with severe symptomatic carotid artery stenosis is unknown. To investigate the effect of stenting compared with medication alone for severe carotid atherosclerotic stenosis on cognitive impairment. Patients with carotid stenosis and cognitive impairment were prospectively randomly divided into 2 groups of stenting or medication alone. Cognitive function was evaluated with the Montreal cognitive assessment (MoCA), Mini-Mental State Examination, and Barthel Index of Activities of Daily Living (BI). Continuous data in normal distribution were tested with the t-test but with the Mann-Whitney U test if not in normal distribution. Categorical data were presented as frequency and percentages and tested with the Fisher exact test. A P value < .05 was regarded as statistical significant. Carotid artery stenting was successfully performed in all patients (100%) in the stenting group. Compared with before treatment, the Mini-Mental State Examination, MoCA and BI scores at 6 months in the medication alone group and at 1, 3, and 6 months in the stenting group were significantly (P < .005) improved. The stenting group had significantly (P < .05) better scores than the medication alone group at the same time. At 6-month follow-up, the visuospatial/executive functions (3.69 ± 1.42 vs 2.42 ± 1.23), attention (5.24 ± 1.52 vs 3.63 ± 1.47), and language (2.64 ± 0.71 vs 1.96 ± 0.69) were significantly (P < .05) improved in the stenting group compared with the medication alone group. Carotid artery stenting may significantly improve cognitive impairment and neurological function compared with medication alone in patients with severe carotid atherosclerotic stenosis concurrent with cognitive impairment.

Association of subclinical atherosclerosis and cognitive decline: a community-based cross-sectional study

BACKGROUND AND AIMS

Growing burden of dementia was considered as a global public health priority as its epidemic scale rises with the world's population increases in age. In the absence of effective treatment, early identification of decline in cognitive function and risk factors that lead to the onset of dementia is a critical issue. Subclinical atherosclerosis may be a potential risk factor for cognitive impairment and progression to dementia. Research is needed to identify which subclinical atherosclerosis risk factors can better predict cognitive decline.

METHODS

A total of 1554 participants (mean age 59.81±6.93 years) were enrolled from Beijing Research on Ageing and Vessel and underwent baseline evaluation. Carotid intima-media thickness, carotid plaque and brachial ankle pulse wave velocity (ba-PWV) were selected as subclinical atherosclerosis markers. Cognitive function assessment was conducted by standardised tasks to assess the associations with subclinical atherosclerosis markers.

RESULTS

Significant associations (p<0.001) were shown in the unadjusted models between all three subclinical atherosclerosis markers and cognitive function assessments. After adjusting for covariates, in the assessment of the association between carotid atherosclerosis and cognitive function, plaque numbers showed significant associations in Montreal Cognitive Assessment (MoCA) (β=-0.15, p=0.006) and verbal memory scores (β=-0.13, p=0.013). While in the assessment of the association between arterial stiffness and cognitive function, ba-PWV showed significant associations in MoCA (β=-0.09, p=0.009) and semantic fluency scores (β=-0.13, p=0.036).

CONCLUSIONS

Positive associations shown between subclinical atherosclerosis and cognitive function. Subclinical atherosclerosis markers of plaque numbers were significantly associated with global cognitive functioning in MoCA, memory and semantic fluency, while ba-PWV was significantly associated with global cognitive functioning in MoCA and semantic fluency.

Intrinsic functional brain connectivity is resilient to chronic hypoperfusion caused by unilateral carotid artery stenosis

•

Unilateral internal carotid artery stenosis leads to chronic cerebral hypoperfusion.

•

rsfMRI functional connectivity is well-compensated in asymptomatic ICA stenosis.

•

Functional network properties remain stable before and after revascularization.

Introduction

Chronic cerebral hypoperfusion caused by asymptomatic high-grade stenosis of the internal carotid artery (ICA) has been associated with impaired cognitive function. Only few studies exist on underlying changes of functional connectivity (FC).

Methods

20 patients with unilateral high-grade ICA stenosis without MRI lesions and 25 aged-match controls underwent resting-state functional MRI (rsfMRI) and neuropsychological assessment. Patients were examined within ten days before and 6–10 weeks after surgical or interventional revascularization of carotid stenosis. We examined mean resting-state FC ipsi- and contralateral to stenosis and network topology using graph-theoretical measures.

Results

At baseline, intrahemispheric FC was similar for patients and healthy controls. After revascularization mean FC increased moderately without an effect on network topology. Patients performed worse in TMT B and Stroop test, while performance in global screening tests for dementia (Mini Mental Status Examination, DemTect) were comparable. Test results did not improve after revascularization.

Conclusion

In our study population, we find no effect of chronic hypoperfusion on FC and global cognitive function, although we observe minor impairments in processing speed and mental flexibility. The subtle increase of FC after revascularization could indicate excessive upregulation after restoration of perfusion. However, it might as well be a coincidental finding due to the limited sample size.

Association between carotid revascularization for asymptomatic stenosis and cognitive functions

Summary: Asymptomatic carotid stenosis (ACS) can cause cognitive dysfunction, related to cerebral hypoperfusion and microemboli. These mechanisms could be treated by carotid revascularization, but the impact of carotid angioplasty stenting (CAS) or carotid endarterectomy (CEA) on cognitive functions remains unclear. The aim of this systematic review was to realize a report on the actual state of results about asymptomatic carotid stenosis revascularization and cognitive function. We performed a systematic literature review to analyze all studies assessing the impact of asymptomatic carotid stenosis revascularizations on cognitive functions. We reviewed all publications published in Medline database and Cochrane between January 2010 and January 2020 including subjects with a cognitive evaluation and receiving carotid revascularization for asymptomatic stenosis. We identified 567 records for review, and finally we included in the systematic review 20 studies about ACS revascularization and cognitive functions. Only observational studies analyzed the impact of CEA and CAS on cognitive functions. Thus, too heterogeneous data associated to the lack of randomized controlled trials with an evaluation of optimal medical treatment did not enable to affirm the interest of the revascularization management of ACS in cognitive domain. There was a lack of standardization and finally studies were too heterogeneous to conclude on the impact of carotid revascularization on cognitive functions. There is an urgent need to harmonize research in this domain in order to prevent and treat cognitive dysfunction related to ACS, especially in our society with an aging population.

Association of Carotid Intima Media Thickening with Future Brain Region Specific Amyloid-β Burden

BACKGROUND

Carotid atherosclerosis is associated with cognitive impairment and dementia, though there is limited evidence of a direct link between carotid disease and amyloid-β (Aβ) burden.

OBJECTIVE

We studied the association of baseline and progressive carotid intima media thickness (CIMT) with Aβ on 11C-Pittsburgh Compound B (PiB) to determine if those with carotid atherosclerosis would have higher Aβ burden.

METHODS

We studied 47 participants from the Framingham Offspring cohort with carotid ultrasounds measuring CIMT at their 6th clinic examination (aged 49.5±5.7 years) and an average of 9.6 years later, and PiB imaging measuring Aβ on average 22.1 years post baseline. We used multivariate linear regression analyses to relate baseline, follow-up, mean, and progression of internal carotid artery (ICA) and common carotid artery (CCA) CIMT to Aβ in brain regions associated with Alzheimer's disease (AD) and related dementias (ADRD), adjusting for age, sex, and other vascular risk factors.

RESULTS

Participants with higher mean ICA IMT had more Aβ in the precuneus (beta±standard error [β±SE]: 0.466±0.171 mm, p = 0.01) and the frontal, lateral, and retrosplenial regions (β±SE: 0.392±0.164 mm, p = 0.022) after adjusting for age, sex, vascular risk factors, and medication use. We did not find an association between any CCA IMT measures and Aβ or progression of ICA or CCA IMT and Aβ.

CONCLUSION

Carotid atherosclerosis, as measured by ICA IMT, is associated with increased Aβ burden later in life. These findings support a link between vascular disease and AD/ADRD pathophysiology.

Degree of cognitive impairment in patients with carotid stenosis in relation to cerebral ischemic lesions

Background/Aim. Carotid stenosis is a risk factor for cognitive impairment. The aim of the study was to evaluate the degree of cognitive impairment in patients with asymp-tomatic and symptomatic carotid stenosis and correlate it with the presence, location, and extent of cerebral ischemic lesions. Methods. A prospective analysis of 180 patients aged 50?70 years, divided into three groups (asymptomatic carotid stenosis, symptomatic carotid stenosis, and controls) was made. We assessed demographic characteristics, vascu-lar risk factors, ultrasound examination of the carotid arter-ies, computerized tomography (CT), magnetic resonance imaging (MRI) of the brain, and neuropsychological testing. Results. The brain CT findings on admission showed is-chemic lesions in the left hemisphere in 13.3% of patients in the asymptomatic group and in 41% of those in the symp-tomatic group. In the right hemisphere, lesions were regis-tered in 10% of the asymptomatic patients and in 46.7% of the symptomatic patients. The difference between groups was statistically significant. The lesion volumes measured on CT and MRI scans were significantly different (p < 0.001) between groups with asymptomatic and symptomatic carot-id stenosis. The degree of cognitive impairment, measured by the Addenbrooke's Cognitive Examination Revised (ACE-R), was significantly different between the groups (p < 0.05), with the most severe deficit in the symptomatic group. Conclusion. Our study has shown that cognitive impairment was more severe in patients with symptomatic carotid stenosis, compared to the patients with asymptomat-ic carotid stenosis.

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

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.

Carotid revascularization and cognitive impairment: the neglected role of cerebral small vessel disease

Carotid atherosclerosis is a pathological process that leads to narrowing of the vessel lumen and a consequent risk of stroke. Revascularization procedures such as carotid endarterectomy (CEA) and carotid stenting aim to reduce occurrence of stroke in selected patients. Due to the proven benefit and low intraoperative risk, CEA is currently the preferred choice in candidates for carotid revascularization. However, the risk of cognitive impairment subsequent to CEA has not been fully elucidated and is unclear whether certain conditions, such as frailty, may increase this risk. There is consistent evidence that shows that frail patients have higher risk of cognitive impairment after surgical procedure. Moreover, brain pre-existing conditions may play a role in cognitive impairment after CEA. Cerebral small vessel disease (SVD) is a pathology that involves microcirculation and is detectable with computed tomography or magnetic resonance. SVD shares common vascular risk factors with carotid atherosclerosis, is a major contributor to vascular cognitive impairment and vascular dementia, and has been proposed as a marker of brain frailty. In this review, we discuss the current evidence about the link between carotid revascularization and cognitive impairment and advance the hypothesis that SVD may play a relevant role in development of cognitive impairment after carotid revascularization.

Comprehensive Evaluation of Cerebral Hemodynamics and Oxygen Metabolism in Revascularization of Asymptomatic High-Grade Carotid Stenosis

Introduction

Revascularization procedures in carotid artery stenosis have shown a positive effect in the restoration of cerebral oxygen metabolism as assessed by T2’ (T2 prime) imaging as well as capillary homeostasis by measurement of capillary transit time heterogeneity (CTH); however, data in patients with asymptomatic carotid stenosis without manifest brain lesions are scarce.

Patients and Methods

The effect of revascularization on the hemodynamic profile and capillary homeostasis was evaluated in 13 patients with asymptomatic high-grade carotid stenosis without ischemic brain lesions using dynamic susceptibility contrast perfusion imaging and oxygenation-sensitive T2’ mapping before and 6–8 weeks after revascularization by endarterectomy or stenting. The cognitive performance at both timepoints was further assessed.

Results

Perfusion impairment at baseline was accompanied by an increased CTH (p = 0.008) in areas with a time to peak delay ≥ 2 s in the affected hemisphere compared to contralateral regions. Carotid intervention improved the overall moderate hemodynamic impairment at baseline by leading to an increase in normalized cerebral blood flow (p = 0.017) and a decrease in mean transit time (p = 0.027), oxygen extraction capacity (OEC) (p = 0.033) and CTH (p = 0.048). The T2’ values remained unchanged.

Conclusion

This study presents novel evidence of a state of altered microvascular function in patients with high-grade carotid artery stenosis in the absence of ischemic brain lesions, which shows sustained normalization after revascularization procedures.

Supplementary Information

The online version of this article (10.1007/s00062-021-01077-3) contains supplementary material, which is available to authorized users.

Carotid Compliance and Parahippocampal and Hippocampal Volume over a 20-Year Period

INTRODUCTION

We evaluated the association between carotid compliance, a measure of arterial stiffness, to parahippocampal volume (PHV) and hippocampal volume (HV) over 20 years later in the Atherosclerosis Risk in the Community study.

METHODS

We included participants with common carotid compliance measurements at visit 1 (1987-1989) and volumetric brain MRI at visit 5 (2011-2013). The primary outcomes are pooled bilateral PHV and HV. We performed linear regression models adjusting for age, sex, vascular risk factors, and total brain volume.

RESULTS

Of the 614 participants, higher compliance was correlated with higher PHV (R = 0.218[0.144-0.291], p < 0.001) and HV (R = 0.181 [0.105-0.255, p < 0.001]). The association was linear and significant after adjusting for confounders. At follow-up MRI, 30 patients with dementia had lower PHV and HV than patients without dementia (p < 0.001 and p < 0.001, respectively).

CONCLUSION

Carotid compliance is associated with higher PHV and HV when measured 20 years later, further supporting the link between arterial stiffness and cognitive decline.

Impact of carotid stenosis on cerebral hemodynamic failure and cognitive impairment progression: a narrative review

Carotid atherosclerosis has a relevant impact on cerebral blood flow regulation. There is accruing evidence that hemodynamic impairment related to the presence of a significant carotid lumen narrowing may predispose to the development of cerebral dysfunctions, including a reduction in cognitive abilities. In the last years an increasing number of findings showed that carotid stenosis did contribute to cognitive impairment not only in relation to the occurrence of cerebral ischemic lesions, but also as an independent risk factor. The principal mechanisms involved are chronic hypoperfusion, microembolization and cerebrovascular reactivity impairment. Moreover, more recent studies showed alterations of regional functional connectivity. In this narrative review, we analyzed the relationships between carotid stenosis, cerebral hemodynamic derangement and cognitive impairment onset and progression, and underlined that cognitive impairment is the final result of the complex interaction between different elements, including also collateral circulation, cerebral hemodynamic status, brain connectivity and pro-inflammatory state. Further, therapeutic approaches, with a specific focus on vascular risk factors correction and on the effectiveness of surgical or endovascular interventions were discussed. We particularly focused our attention on the concept of “asymptomatic carotid stenosis”, and how could a cognitive impairment improve after an intervention, and how this could change the indications to surgical approach. Larger studies and randomized controlled trials are urgently required to better define time, characteristics and effectiveness of both medical and surgical/endovascular approaches.

Disrupted Topological Organization of Functional Networks in Asymptomatic Carotid Plaque Without Significant Carotid Stenosis: A Resting-State fMRI Study

Purpose: Previous studies have found that there are significant changes in functional network properties for patients with moderate to severe carotid artery stenosis. Our study aimed to explore the topology properties of brain functional network in asymptomatic patients with carotid plaque without significant stenosis.

Methods: A total of 61 asymptomatic patients with carotid plaque (mean age 61.79 ± 7.35 years) and 25 healthy control subjects (HC; 58.12 ± 6.79 years) were recruited. General data collection, carotid ultrasound examination and resting state functional magnetic resonance imaging were performed on all subjects. Graph-theory was applied to examine the differences in the brain functional network topological properties between two groups.

Results: In the plaque group, E_loc(P = 0.03), γ (P = 0.01), and σ (P = 0.01) were significantly higher than in the HC group. The degree centrality of left middle frontal gyrus and the nodal efficiency of left middle frontal gyrus and right inferior parietal angular gyrus were significantly higher in the plaque group than in HC. The degree centrality and betweenness centrality of right middle temporal gyrus, as well as the nodal efficiency of right middle temporal gyrus, were significantly lower in the plaque group than in HC.

Conclusions: The brain functional networks of patients with carotid plaques differ from those of healthy controls. Asymptomatic patients with carotid plaques exhibit increased local and global connectivity, which may reflect subtle reorganizations in response to early brain damage.

Imaging retinal microvascular manifestations of carotid artery disease in older adults: from diagnosis of ocular complications to understanding microvascular contributions to cognitive impairment

Carotid artery stenosis (CAS) is a consequence of systemic atherosclerotic disease affecting the aging populations of the Western world. CAS is frequently associated with cognitive impairment. However, the mechanisms contributing to the development of vascular cognitive impairment (VCI) associated with CAS are multifaceted and not fully understood. In addition to embolization and decreased blood flow due to the atherosclerotic lesion in the carotid artery, microcirculatory dysfunction in the cerebral circulation also plays a critical role in CAS-related VCI. To better understand the microvascular contributions to cognitive decline associated with CAS and evaluate microvascular protective effects of therapeutic interventions, it is essential to examine the structural and functional changes of the microvessels in the central nervous system (CNS). However, there are some limitations of in vivo brain vascular imaging modalities. The retinal microvasculature provides a unique opportunity to study pathogenesis of cerebral small vessel disease and VCI, because the cerebral circulation and the retinal circulation share similar anatomy, physiology and embryology. Similar microvascular pathologies may manifest in the brain and the retina, thus ocular examination can be used as a noninvasive screening tool to investigate pathological changes in the CNS associated with CAS. In this review, ocular signs of CAS and the retinal manifestations of CAS-associated microvascular dysfunction are discussed. The advantages and limitation of methods that are capable of imaging the ocular circulation (including funduscopy, fluorescein angiography, Doppler sonography, optical coherence tomography [OCT] and optical coherence tomography angiography [OCTA]) are discussed. The potential use of dynamic retinal vessel analysis (DVA), which allows for direct visualization of neurovascular coupling responses in the CNS, for understanding microvascular contributions to cognitive decline in CAS patients is also considered.

Subclinical Carotid Artery Atherosclerosis and Cognitive Function: A Mini-Review

Carotid artery atherosclerosis, the result of a multitude of vascular risk factors, is a promising marker for use in risk stratification. Recent evidence suggests that carotid artery atherosclerosis affects cognitive function and is an independent risk factor for the development of cognitive impairment. Both atherosclerosis and cognitive impairment develop over a prolonged period (years), and due to the aging population, markers to identify persons at risk are needed. Carotid artery atherosclerosis can easily be visualized using non-invasive ultrasound, potentially enabling early and intensified risk factor management to preserve cognitive function or delay further decline. However, the burden of atherosclerosis and temporal exposure required to pose a risk of cognitive impairment is unclear. This mini-review aims to explore the available evidence on the association between carotid atherosclerosis and cognition, and furthermore identify the remaining gaps in knowledge.

Measurement of Cortical Atrophy and Its Correlation to Memory Impairment in Patients With Asymptomatic Carotid Artery Stenosis Based on VBM-DARTEL

Objective

Severe carotid artery stenosis (CAS) can lead to atrophy of gray matter (GM) and memory impairment; however, the underlying mechanism is unknown. Thus, we aimed to identify memory impairment and GM atrophy and explore the possible correlation between them in patients with asymptomatic severe CAS.

Methods

Twenty-four patients with asymptomatic severe CAS and 10 healthy controls completed the mini-mental state examination (MMSE) and clinical memory scale (CMS) and underwent 7T magnetic resonance imaging (MRI) scan. Field intensity inhomogeneities were corrected. Images were processed using VBM8, and GM images were flipped. First, 11 flipped and 10 non-flipped images of patients with unilateral CAS and 5 flipped and 5 non-flipped images of controls were pre-processed using DARTEL algorithm and analyzed using an analysis of variance (ANOVA). Second, flipped and non-flipped images of unilateral patients were similarly pre-processed and analyzed using the paired t-test. Third, pre-processed non-flipped GM images and CMS scores of 24 patients were analyzed by multiple regression analysis. Nuisance variables were corrected accordingly.

Results

Basic information was well matched between patients and controls. MMSE scores of patients were in the normal range; however, memory function was significantly reduced (all P < 0.05). GM volumes of patients were significantly reduced in the anterior circulation regions. The stenosis-side hemispheres showed greater atrophy. GM volumes of the left pars opercularis, pars triangularis, and middle frontal gyrus were strongly positively correlated with the total scores of CMS (all r > 0.7, P = 0.001). Additionally, the left middle frontal gyrus was strongly positively correlated with associative memory (r = 0.853, P = 0.001). The left pars opercularis was moderately positively correlated with semantic memory (r = 0.695, P = 0.001).

Conclusion

Patients with asymptomatic CAS suffer from memory impairment. Bilateral anterior circulation regions showed extensive atrophy. The hemisphere with stenosis showed severer atrophy. Memory impairment in patients may be related to atrophy of the left frontal gyrus and atrophy of different regions may result in different memory impairments.

Editor's Choice - Asymptomatic Carotid Stenosis and Cognitive Impairment: A Systematic Review

OBJECTIVE

The aim was to evaluate the relationship between asymptomatic carotid stenosis (ACS) of any severity and cognitive impairment and to determine whether there is evidence supporting an aetiological role for ACS in the pathophysiology of cognitive impairment.

DATA SOURCES

PubMed/Medline, Embase, Scopus, and the Cochrane library.

REVIEW METHODS

This was a systematic review (35 cross sectional or longitudinal studies) RESULTS: Study heterogeneity confounded data interpretation, largely because of no standardisation regarding cognitive testing. In the 30 cross sectional and six longitudinal studies (one included both), 33/35 (94%) reported an association between any degree of ACS and one or more tests of impaired cognitive function (20 reported one to three tests with poorer cognition; 11 reported four to six tests with poorer cognition, while three studies reported seven or more tests with poorer cognition). There was no evidence that ACS caused cognitive impairment via silent cortical infarction, or via involvement in the pathophysiology of lacunar infarction or white matter hyperintensities. However, nine of 10 studies evaluating cerebral vascular reserve (CVR) reported that ACS patients with impaired CVR were significantly more likely to have cognitive impairment and that impaired CVR was associated with worsening cognition over time. Patients with severe ACS but normal CVR had cognitive scores similar to controls.

CONCLUSION

Notwithstanding significant heterogeneity within the constituent studies, which compromised overall interpretation, 94% of studies reported an association between ACS and one or more tests of cognitive impairment. However, "significant association" does not automatically imply an aetiological relationship. At present, there is no clear evidence that ACS causes cognitive impairment via silent cortical infarction (but very few studies have addressed this question) and no evidence of ACS involvement in the pathophysiology of white matter hyperintensities or lacunar infarction. There is, however, better evidence that patients with severe ACS and impaired CVR are more likely to have cognitive impairment and to suffer further cognitive decline with time.

The effect of intracranial stenosis on cognitive decline in a memory clinic cohort

BACKGROUND AND PURPOSE

Intracranial stenosis (ICS) is a risk factor for cognitive impairment and dementia in cross-sectional studies. However, data examining the effect of ICS on cognitive decline are limited. We investigated the effect of ICS on cognition over a period of 3 years in a memory clinic cohort.

METHODS

Patients were recruited from the National University Hospital in Singapore. Data were collected using a standardised questionnaire, physical examination, and 3-T magnetic resonance imaging (MRI) at baseline. ICS was defined as arterial narrowing that exceeded 50% of the luminal diameter in any intracranial vessel. Cognition was measured at baseline and annually for 3 years using the Mini-Mental State Examination, the Montreal Cognitive Assessment, and a detailed neuropsychological test battery. The association between ICS and cognitive decline was analysed using generalised estimating equations.

RESULTS

A total of 364 patients were included in the analysis. The mean (±SD) age was 71.9 (±8.0) years, and 164 (45.1%) patients were male. A total of 66 (18.1%) patients had ICS. ICS was associated with worse executive function (β = -0.37, 95% confidence interval = -0.68 to -0.05, p = 0.022) and modified the effect of follow-up time on memory (p = 0.005) and visuomotor speed (p = 0.047). These results remained significant after controlling for demographics, overall diagnosis, cardiovascular risk factors, and MRI markers of cerebrovascular disease.

CONCLUSIONS

Intracranial stenosis was independently associated with worse executive function across all time points, and cognitive decline in memory and visuomotor speed over 3 years of follow-up. This suggests that ICS may be a useful indicator of vascular brain damage leading to cognitive decline and may warrant consideration of antiatherosclerotic treatment in clinical trials.

The Effects of Intracranial Stenosis on Cerebral Perfusion and Cognitive Performance

Background: Intracranial stenosis (ICS) may contribute to cognitive dysfunction by decreased cerebral blood flow (CBF) which can be measured quantitatively by arterial spin labelling (ASL). Interpretation of CBF measurements with ASL, however, becomes difficult in patients with vascular disease due to prolonged arterial transit time (ATT). Recently, spatial coefficient of variation (sCoV) of ASL signal has been proposed that approximates ATT and utilized as a proxy marker for assessment of hemodynamic status of cerebral circulation. Objective: We investigate the association of ICS with CBF and sCoV parameters and its eventual effects on cognition in a memory clinic population. Methods: We included 381 patients (mean age = 72.3±7.9 years, women = 53.7%) who underwent 3T MRI and detailed neuropsychological assessment. ICS was defined as≥50% stenosis in any intracranial vessel on 3D Time-of-Flight MR Angiography. Gray matter sCoV and CBF were obtained from 2D EPI pseudo-continuous ASL images. Results: ICS was present in 58 (15.2%) patients. Patients with ICS had higher gray matter sCoV and lower CBF. The association with sCoV remained statistically significant after correction for cardiovascular risk factors. Moreover, ICS was associated with worse performance on visuoconstruction, which attenuated with higher sCoV. Mediation analysis showed that there was an indirect effect of ICS on visuoconstruction via sCoV. Conclusion: These findings suggest that compromised CBF as detected by higher sCoV is related to cognitive impairment among individuals diagnosed with ICS. We also showed that sCoV partially mediates the link between ICS and cognition. Therefore, sCoV may provide valuable hemodynamic information in patients with vascular disease.

Carotid Revascularization Improves Cognition in Patients With Asymptomatic Carotid Artery Stenosis and Cognitive Decline. Greater Improvement in Younger Patients With More Disordered Neuropsychological Performance

OBJECTIVES

There has been a growing interest in whether carotid revascularization may reverse cognitive decline. In this study the aim was to assess cognitive changes after carotid artery endarterectomy and stenting, using neuropsychological assessment with MoCA and CANTAB test.

MATERIALS AND METHODS

Seventy patients with asymptomatic carotid artery stenosis, qualified for CEA (study group A) and CAS (study group B) have been prospectively assessed. 20 patients with lower extremity artery disease (control group C) and 15 patients qualified for inguinal hernia surgery (control group D) have served as a control group. Patients have been evaluated 1 day before surgery and 6 months after, using MoCA and CANTAB test. Logistic regression models were built to determine variables affecting cognitive performance.

RESULTS

After the procedure in the study group A the cognitive evaluation showed improvement in 5 cognitive domains tested in MoCA: visuospatial/executive (p=.0496), naming (p=.0831), language (p=.0009), abstraction (p=.0126) and delayed recall (p=.0016). In CANTAB there were improvement in PAL (p=.0290) and SWM (p=.0105). In study group B positive cognitive changes were seen in visuospatial/executive (p=.0827) and delayed recall (p=.0041) tested with MoCA and in PAL (PALFAMS28 p=.0315, PALNPR28 p=.0090, PALTEA28 p=.0058) and SWM (p=.0882) tested with CANTAB. Using a regression model, the only strong predictors of cognitive improvement on the follow-up visit were younger age and lower MoCA score on the first visit.

CONCLUSIONS

Carotid revascularization, both open and endovascular, lead to cognitive improvement in patients with severe carotid stenosis and cognitive decline. This effect seems to be stronger in younger patients with worst cognitive performance before surgery.

Asymptomatic carotid artery stenosis is associated with cerebral hypoperfusion

OBJECTIVE

We have shown that almost 50% of patients with asymptomatic carotid stenosis (ACS) will demonstrate cognitive impairment. Recent evidence has suggested that cerebral hypoperfusion is an important cause of cognitive impairment. Carotid stenosis can restrict blood flow to the brain, with consequent cerebral hypoperfusion. In contrast, cross-hemispheric collateral compensation through the Circle of Willis, and cerebrovascular vasodilation can also mitigate the effects of flow restriction. It is, therefore, critical to develop a clinically relevant measure of net brain perfusion in patients with ACS that could help in risk stratification and in determining the appropriate treatment. To determine whether ACS results in cerebral hypoperfusion, we developed a novel approach to quantify interhemispheric cerebral perfusion differences, measured as the time to peak (TTP) and mean transit time (MTT) delays using perfusion-weighted magnetic resonance imaging (PWI) of the whole brain. To evaluate the utility of using clinical duplex ultrasonography (DUS) to infer brain perfusion, we also assessed the relationship between the PWI findings and ultrasound-based peak systolic velocity (PSV).

METHODS

Structural and PWI of the brain and magnetic resonance angiography of the carotid arteries were performed in 20 patients with ≥70% ACS. DUS provided the PSV, and magnetic resonance angiography provided plaque geometric measures at the stenosis. Volumetric perfusion maps of the entire brain from PWI were analyzed to obtain the mean interhemispheric differences for the TTP and MTT delays. In addition, the proportion of brain volume that demonstrated a delay in TTP and MTT was also measured. These proportions were measured for increasing severity of perfusion delays (0.5, 1.0, and 2.0 seconds). Finally, perfusion asymmetries on PWI were correlated with the PSV and stenosis features on DUS using Pearson's correlation coefficients.

RESULTS

Of the 20 patients, 18 had unilateral stenosis (8 right and 10 left) and 2 had bilateral stenoses. The interhemispheric (left-right) TTP delays measured for the whole brain volume identified impaired perfusion in the hemisphere ipsilateral to the stenosis in 16 of the 18 patients. More than 45% of the patients had had ischemia in at least one half of their brain volume, with a TTP delay >0.5 second. The TTP and MTT delays showed strong correlations with PSV. In contrast, the correlations with the percentage of stenosis were weaker. The correlations for the PSV were strongest with the perfusion deficits (TTP and MTT delays) measured for the whole brain using our proposed algorithm (r = 0.80 and r = 0.74, respectively) rather than when measured on a single magnetic resonance angiography slice as performed in current clinical protocols (r = 0.31 and r = 0.58, respectively).

CONCLUSIONS

Interhemispheric TTP and MTT delay measured for the whole brain using PWI has provided a new tool for assessing cerebral perfusion deficits in patients with ACS. Carotid stenosis was associated with a detectable reduction in ipsilateral brain perfusion compared with the opposite hemisphere in >80% of patients. The PSV measured at the carotid stenosis using ultrasonography correlated with TTP and MTT delays and might serve as a clinically useful surrogate to brain hypoperfusion in these patients.

Carotid Atherosclerosis and Cognitive Function in a General Population Aged 63-65 Years: Data from the Akershus Cardiac Examination (ACE) 1950 Study

BACKGROUND

Studies on the relationship between carotid atherosclerosis and cognitive function in subjects from the general population are few and results have been inconsistent.

OBJECTIVE

We aimed to investigate the association between carotid atherosclerotic burden and cognitive function in a cross-sectional analysis of a population-based cohort aged 63-65 years.

METHODS

All habitants born in 1950 from Akershus County, Norway were invited to participate. A linear regression model was used to assess the association between carotid atherosclerosis and cognitive function. We used carotid plaque score as a measure of carotid atherosclerotic burden and the Montreal Cognitive Assessment (MoCA) for global cognitive function.

RESULTS

We analyzed 3,413 individuals aged 63-65 with mean MoCA score 25.3±2.9 and 87% visible carotid plaques. We found a negative correlation between carotid plaque score and MoCA score (r = -0.14, p < 0.001), but this association was lost in multivariable analysis. In contrast, diameter or area of the thickest plaque was independently associated with MoCA score. Lower educational level, male sex, current smoking, and diabetes were also associated with lower MoCA score in multivariable analysis.

CONCLUSION

Carotid atherosclerotic burden was, unlike other measures of advanced carotid atherosclerosis, not independently associated with global cognitive function.

Is it possible to prevent cerebral embolization by improving the design and technology of carotid stent implantation?

INTRODUCTION

The prevention of atherosclerotic plaque fragmentation during carotid artery stenting is a fundamental problem in decreasing the risk of disability of patients. The goal of this review is to clarify whether the stent design can have a decisive impact on the rate of intraoperative and postoperative complications.

AREAS COVERED

Different designs of the carotid stents are briefed and the advantages and disadvantages of different stent designs are discussed as well as the results of their clinical use. Various solutions are presented to reduce cerebral embolism during carotid artery stenting.

EXPERT OPINION

There is no conclusive evidence for the benefits of closed cell and hybrid stents. The stent design cannot completely resolve the problem of cerebral embolism. Most of the events of cerebral microembolism occur at the stages of stent delivery rather than protrusion of an atherosclerotic plaque in the long-term follow-up. Most likely, minimization of the risks for periprocedural and postprocedural strokes requires not only the new solutions in stent design as well as the corresponding delivery systems and brain embolic protection systems, but also the new strategies of preprocedural drug stabilization of the atherosclerotic plaque in the carotid artery. Abbreviations: CAS, carotid artery stenting; CE, carotid endarterectomy; DW-MRI, diffusion-weighted magnetic resonance imaging; ECA, external carotid artery; ICA, internal carotid artery; IVUS, intravascular ultrasound examination; OCT, optical coherence tomography.

Normalization of reduced functional connectivity after revascularization of asymptomatic carotid stenosis

Internal carotid artery stenosis is a risk factor for ischemic stroke. Even in the absence of visible structural brain changes, patients with asymptomatic stenosis are prone to cognitive impairment. On a neuronal level, it was suggested that stenosis may lead to disturbed functional brain connectivity. If so, carotid revascularization should have an effect on hypothesized brain network disturbances. We studied functional connectivity in a motor network by resting-state electroencephalography in 12 patients with high grade asymptomatic carotid stenosis before and after interventional or surgical revascularization as compared to 23 controls. In patients with stenosis, functional connectivity of neural oscillations was significantly decreased prior and improved returning to normal connectivity after revascularization. In a subgroup of patients, also studied by contrast perfusion magnetic resonance imaging, reduced connectivity was associated with decreased regional brain perfusion reflected by increased mean transit time in the middle cerebral artery borderzone. Cognitive testing revealed only minor differences between patients and controls. In summary, we identified oscillatory connectivity changes in patients with asymptomatic carotid stenosis correlating with regional hypoperfusion, which both normalized after revascularization. Hence, electrophysiological changes might be a reversible precursor preceding macroscopic structural brain damage and behavioral impairment in patients with asymptomatic carotid stenosis.

Micro-structural white matter abnormalities and cognitive impairment in asymptomatic carotid plaque patients: A DTI study using TBSS analysis

BACKGROUND

It has been shown that symptomatic or severe carotid atherosclerosis is closely related to cognitive impairment and brain white matter damage. However, there is still a lack of effective and non-invasive imaging biomarkers to identify early high-risk cerebrovascular diseases. Therefore, the purpose of this study is to explore the integrity of brain white matter and cognitive impairment in patients with asymptomatic carotid plaques by using imaging technology.

METHODS

All subjects were from a project of Stroke Risk Screening and Prevention and were defined as stroke high-risk patients (with three or more stroke risk factors). Tract-based spatial statistics (TBSS) based on diffusion tensor imaging (DTI) was used to analyze the whole brain white matter abnormalities in 61 patients with carotid artery plaque and in 40 healthy controls. At the same time, the general clinical data between the two groups were compared, such as age, gender, smoking, hypertension and cognitive function scores etc. Furthermore, the plaque group was divided into the have-hyperintensities group and the no-hyperintensities group to compare their microstructure of white matter injuries.

RESULTS

The cognitive scores of plaque group were significantly lower than that of control group. We found that when plaque group and control group were compared, no white matter fiber tracts with difference was found in FA, MD, AD and RD. However, the decrease of FA and the increase of RD were found in some white matter regions (P < 0.05) when comparing the have-hyperintensities group and the no-hyperintensities group. These white matter regions included anterior thalamic radiation, corticospinal tract, cingulum (cingulate gyrus), forceps minor, inferior fronto-occipital fasciculus, superior longitudinal fasciculus, uncinate fasciculus. What's more, there were significant differences in blood pressure between the two groups.

CONCLUSION

The cognitive function of patients with early high-risk cerebrovascular diseases (asymptomatic carotid plaques) has a downward trend. TBSS based on DTI can help to find out the actual damage of brain white matter in patients with early carotid plaque, and reflect the early pathological changes from the micro level.

Association Between Asymptomatic Vulnerable Carotid Plaques and Cognitive Impairment in Rural Adults

Background: The prevalence of cognitive impairment is growing and higher in rural areas. The association between carotid plaque and cognitive impairment remains uncertain, and few studies focused on the cognitive function of the rural population. We designed this study to investigate the association between carotid plaque and cognitive impairment in a rural community. Methods: We enrolled 3,336 participants who underwent carotid ultrasound and cognitive function measurements, free of cerebrovascular diseases, and without neurological deficits, from the China National Stroke Screen Survey program. Cognitive function was evaluated by the Montreal Cognitive Assessment (Beijing version). We used multivariable logistic regression to assess the association between asymptomatic carotid plaques and the presence of cognitive impairment. Results: Nine hundred seventy-six participants had cognitive impairment in this study. After adjustment for potential confounding factors, asymptomatic carotid plaques (odds ratio was 1.35; 95% confidence interval, 1.15-1.58), especially vulnerable carotid plaques (odds ratio was 1.54; 95% confidence interval, 1.28-1.85), were associated with cognitive impairment. Conclusion: In this community-based and observational study, asymptomatic vulnerable carotid plaque is an independent and significant risk factor for cognitive impairment in rural residents.

The progression of carotid atherosclerosis and imaging markers of dementia

INTRODUCTION

We studied the association of carotid intima-media thickness (CIMT) with hippocampal volume (HV) in community dwelling individuals, testing the hypothesis that persons with carotid atherosclerosis progression would have lower HV.

METHODS

We studied 1376 Framingham Offspring participants with two carotid ultrasounds and brain magnetic resonance imaging (MRIs). We used multivariable linear regression analyses to relate CIMT progression and HV and total brain volume. Regression models were adjusted for demographics and vascular risk factors, time interval between imaging examinations, and baseline CIMT. We assessed effect modification by hypertension treatment (HRx).

RESULTS

Participants with higher ICA IMT progression had significantly lower HV after adjustment for vascular risk factors and baseline IMT (standardized beta ± standard error: -0.067 ± 0.027, P = .01). We observed weaker association between ICA IMT change and HV among subjects treated for hypertension (β = -0.047, P = .19 vs β = -0.096, P = .026).

DISCUSSION

Cumulative vascular risk factor exposure, reflected by CIMT progression, may increase the risk of neurodegeneration.

Mismatch of cognition and neural networks in asymptomatic middle cerebral artery steno-occlusive disease

BACKGROUND AND PURPOSE

The role of intracranial steno-occlusive disease in cognitive impairment and dementia is unclear and has not been well studied.

METHODS

A total of 32 consecutive patients (13 males, aged 54 ± 12 years) with asymptomatic steno-occlusive middle cerebral artery (MCA) disease, defined as >70% stenosis on maximum intensity projection images or a complete signal loss of MCA trunk on magnetic resonance angiography, and 20 age- and education-matched normal controls (12 males, 60 ± 8 years old) were compared for neuropsychological performance, gray matter volume and neural network analysis.

RESULTS

The patient group did not show a significant decrease in gray matter volume or cognitive tests except for their performance on the grooved pegboard test. However, graph analysis of resting-state functional magnetic resonance imaging showed significant decreases in network strength, global efficiency and the clustering coefficient, as well as a longer characteristic path length (P < 0.05). The diffusive decrease pattern was particularly located in interhemispheric connectivity and there was no compensatory hyperconnectivity in any brain regions.

CONCLUSION

In asymptomatic steno-occlusive MCA disease, cognition and neural network changes are mismatched and have underlying pathophysiological mechanisms that are different from those of neurodegenerative disease.

The stronger one-sided relative hypoperfusion, the more pronounced ipsilateral spatial attentional bias in patients with asymptomatic carotid stenosis

Patients with asymptomatic, high-grade internal carotid artery stenosis often suffer from subtle cognitive impairments with unclear underlying neuro-cognitive mechanisms. Thus, we hypothesized that stenosis-related unilateral cerebral hypoperfusion leads to an ipsilateral attentional bias; 22 patients with asymptomatic, one-sided high-grade carotid stenosis and 24 age-matched healthy controls underwent pseudo-continuous arterial spin labeling to assess brain perfusion in the territory of the carotid arteries. Furthermore, a parametric assessment of attention functions was carried out on the basis of the computational Theory of Visual Attention. Both patients' perfusion and spatial attention were significantly more lateralized than those of healthy controls. Critically, both asymmetry indices were significantly correlated in patients, i.e. the stronger one-sided relative hypoperfusion, the stronger ipsilateral bias of attention. This association was specifically pronounced in parietal cortices and independent of white matter hyperintensities as a surrogate for cerebrovascular brain damage. Results provide evidence for a link between lateralized hypoperfusion and lateralized attentional weighting in asymptomatic, high-grade carotid stenosis. Data suggest that lateralized hypoperfusion with simultaneous spatial attentional bias might serve as a potential therapeutic target in one-sided carotid stenosis.

Frequent Cognitive Impairment in Patients With Disorders Along the Heart-Brain Axis

Background and Purpose—

Patients with cardiovascular disease are at increased risk for cognitive decline. We studied the occurrence and profile of cognitive impairment in 3 patient groups as exemplar conditions of hemodynamic disturbances at different levels of the heart-brain axis, including patients with heart failure (HF), carotid occlusive disease (COD), and patients with cognitive complaints and vascular brain injury on magnetic resonance imaging (possible vascular cognitive impairment [VCI]).

Methods—

In 555 participants (160 HF, 107 COD, 160 possible VCI, 128 reference participants; 68±9 years; 36% F; Mini-Mental State Examination 28±2), we assessed cognitive functioning with a comprehensive test battery. Test scores were transformed into z -scores. Compound z -scores were constructed for: memory, language, attention/psychomotor speed, executive functioning, and global cognitive functioning. We rated cognitive domains as impaired when z -score≤−1.5. Based on the number of impaired domains, patients were classified as cognitively normal, minor, or major cognitive impairment. We used general linear models and χ 2 tests to compare cognitive functioning between patient groups and the reference group.

Results—

Age, sex, and education adjusted global cognitive functioning z-score was lower in patients with COD (β [SE]=−0.46 [0.10], P <0.001) and possible VCI (β [SE]=−0.80 [0.09], P <0.001) compared with reference participants. On all domains, z -scores were lower in patients with COD and possible VCI compared with reference participants. Patients with HF had lower z-scores on attention/speed and language compared with reference participants. Cognitive impairment was observed in 18% of HF, 36% of COD, and 45% possible VCI. There was no difference in profile of impaired cognitive domains between patient groups. Memory and attention-psychomotor speed were most commonly affected, followed by executive functioning and language.

Conclusions—

A substantial part of patients with HF and COD had cognitive impairment, which warrants vigilance for the occurrence of cognitive impairment. These results underline the importance of an integrative approach in medicine in patients presenting with disorders in the heart-brain axis.

Cortical Cerebral Microinfarcts on 3T Magnetic Resonance Imaging in Patients With Carotid Artery Stenosis

Background and Purpose- Carotid artery stenosis is common in the elderly and contributes to cognitive impairment and dementia. Cortical cerebral microinfarcts (CMIs) play an important role in vascular cognitive impairment and dementia. We aimed to investigate the association between CMIs on 3T magnetic resonance imaging and clinical and radiological features, including plaque morphology, and cognitive function in patients with carotid stenosis. Methods- Eighty-nine patients with >30% carotid stenosis on ultrasound were prospectively enrolled, and underwent brain and carotid artery magnetic resonance imaging. CMIs were rated according to predetermined criteria based on 3D-double inversion recovery and fluid-attenuated inversion recovery images. Results- CMIs were identified in 26 patients (29%; median number 0, range 0-9). Poisson regression models adjusted for age and sex revealed that CMIs were associated with intraplaque hemorrhage (rate ratio, 1.95; 95% CI, 1.26-3.18), lacunar infarcts (rate ratio, 1.54; 95% CI, 1.00-2.44), and cortical infarcts (rate ratio, 3.22; 95% CI, 2.20-5.00). These associations were also observed in asymptomatic patients (n=64). Of 81 patients with unilateral carotid stenosis, the prevalence and number of CMIs were significantly higher in the hemisphere ipsilateral to the carotid stenosis than in the contralateral hemisphere ( P=0.005 and P<0.001, respectively). The presence of CMIs was associated with poor cognitive function. Conclusions- Our results indicate that vulnerable carotid plaque increases the risk of CMIs and subsequent cognitive impairment. Carotid atherosclerosis could be a potential therapeutic target for cognitive impairment.

Tamoxifen promotes white matter recovery and cognitive functions in male mice after chronic hypoperfusion

Cerebral white matter lesions (WMLs) induced by chronic cerebral hypoperfusion are one of the major components of stroke pathology and closely associated with cognitive impairment. However, the repair and related pathophysiology of white matter after brain injury remains relatively elusive and underexplored. Successful neuroregeneration is a method for the potential treatment of central nervous system (CNS) disorders. A non-steroidal estrogen receptor modulator, Tamoxifen, is an effective inhibitor of cell-swelling-activated anion channels and can mimic neuroprotective effects of estrogen in experimental ischemic stroke. However, its remains unclear whether Tamoxifen has beneficial effects in the pathological process after WMLs. In the present study, we investigated the efficacy of Tamoxifen on multiple elements of oligovascular niche of the male C57BL/6 mice brain after bilateral carotid artery stenosis (BCAS) - induced WMLs. Tamoxifen was injected intraperitoneally once daily from 1 day after BCAS until 1 day before sacrificed. Following chronic hypoperfusion, BCAS mice presented white matter demyelination, loss of axon-glia integrity, activated inflammatory response, and cognitive impairments. Tamoxifen treatment significantly facilitated functional restoration of working memory impairment in mice after white matter injury, thus indicating a translational potential for this estrogen receptor modulator given its clinical safety and applicability for WMLs, which lack of currently available treatments. Furthermore, Tamoxifen treatment reduced microglia activation and inflammatory response, favored microglial polarization toward to the M2 phenotype, enhanced oligodendrocyte precursor cells proliferation and differentiation, and promoted remyelination after chronic hypoperfusion. Together, our data indicate that Tamoxifen could alleviate white matter injury and play multiple targets protective effects following chronic hypoperfusion, which is a promising candidate for the therapeutic target for ischemic WMLs and other demyelination diseases associated cognitive impairment.

Asymptomatic carotid stenosis and concomitant silent brain infarctions

Objectives

This review aims to clarify (1) the definition of silent brain infarct (SBI), (2) the diagnostic criteria of SBI using magnetic resonance imaging (MRI), (3) the prevalence of patients with asymptomatic carotid stenosis and SBI based on MRI assessment, (4) the association of SBI and asymptomatic carotid stenosis and the risk of stroke compared to patients without SBI, (5) the association between development of dementia/cognitive impairment in people with asymptomatic carotid stenosis and SBI, and (6) the evidence for treating patients with carotid stenosis and SBI.

Methods

A systematic search of PubMed and Scopus including all studies published from 2000 to 2018 and written in English.

Results

No consensus of the definition and diagnostic criteria for SBI was found. The prevalence of SBI in asymptomatic carotid patients is 17–33.3%. SBI is a significant risk factor for future stroke, OR 4.6 (95% CI: 3.0–7.2; p < 0.0001). One substudy showed that immediate CEA is beneficial compared to delayed CEA in these patients, showing a 45% reduction in annual stroke rate from 1.5%/year to 0.7%/year.

Conclusion

This review emphasizes the need to standardize the definition and diagnostic criteria of SBI on MRI. Current evidence suggests an increased risk and a small potential benefit of offering carotid endarterectomy to patient with silent brain infarct. Prospective studies are warranted to elucidate these issues further.

Cortical thickness and cognitive performance in asymptomatic unilateral carotid artery stenosis

Background

We investigated changes of cortical thickness and its association with cognitive performance in patients with high-grade carotid artery stenosis without ischemic brain lesions.

Methods

We studied 25 patients with unilateral carotid artery stenosis ≥50% and 25 age-matched controls. All subjects underwent T1-weighted MRI, and cortical thickness was measured in 33 regions of interest in each hemisphere, as well as in brain regions belonging to the vascular territory of the middle cerebral artery (MCA). General linear mixed models were fitted to the dependent variable cortical thickness. Cognitive assessment comprised the Stroop Test and Trail Making Test B.

Results

In the linear mixed model, presence of carotid stenosis had no effect on cortical thickness. There was a significant interaction of stenosis and region with a trend towards lower cortical thickness in the MCA region on the side of carotid stenosis. Patients with carotid stenosis performed significantly worse on the Stroop test than controls, but there was no correlation with cortical thickness.

Conclusion

In patients with carotid stenosis without ischemic brain lesions, neither a clear pattern of reduced cortical thickness nor an association of cortical thickness with cognitive function was observed. Our data do not support the hypothesized association of cortical thinning and cognitive impairment in carotid stenosis.

Electronic supplementary material

The online version of this article (10.1186/s12872-019-1127-y) contains supplementary material, which is available to authorized users.