Cognitive impairment and intracranial atherosclerotic stenosis in general population

Risk prediction for elderly cognitive impairment by radiomic and morphological quantification analysis based on a cerebral MRA imaging cohort

OBJECTIVE

To establish morphological and radiomic models for early prediction of cognitive impairment associated with cerebrovascular disease (CI-CVD) in an elderly cohort based on cerebral magnetic resonance angiography (MRA).

METHODS

One-hundred four patients with CI-CVD and 107 control subjects were retrospectively recruited from the 14-year elderly MRA cohort, and 63 subjects were enrolled for external validation. Automated quantitative analysis was applied to analyse the morphological features, including the stenosis score, length, relative length, twisted angle, and maximum deviation of cerebral arteries. Clinical and morphological risk factors were screened using univariate logistic regression. Radiomic features were extracted via least absolute shrinkage and selection operator (LASSO) regression. The predictive models of CI-CVD were established in the training set and verified in the external testing set.

RESULTS

A history of stroke was demonstrated to be a clinical risk factor (OR 2.796, 1.359-5.751). Stenosis ≥ 50% in the right middle cerebral artery (RMCA) and left posterior cerebral artery (LPCA), maximum deviation of the left internal carotid artery (LICA), and twisted angles of the right internal carotid artery (RICA) and LICA were identified as morphological risk factors, with ORs of 4.522 (1.237-16.523), 2.851 (1.438-5.652), 1.373 (1.136-1.661), 0.981 (0.966-0.997) and 0.976 (0.958-0.994), respectively. Overall, 33 radiomic features were screened as risk factors. The clinical-morphological-radiomic model demonstrated optimal performance, with an AUC of 0.883 (0.838-0.928) in the training set and 0.843 (0.743-0.943) in the external testing set.

CONCLUSION

Radiomics features combined with morphological indicators of cerebral arteries were effective indicators for early signs of CI-CVD in elderly individuals.

KEY POINTS

Question The relationship between morphological features of cerebral arteries and cognitive impairment associated with cerebrovascular disease (CI-CVD) deserves to be explored. Findings The multipredictor model combining with stroke history, vascular morphological indicators and radiomic features of cerebral arteries demonstrated optimal performance for the early warning of CI-CVD. Clinical relevance Stenosis percentage and tortuosity score of the cerebral arteries are important risk factors for cognitive impairment. The radiomic features combined with morphological quantification analysis based on cerebral MRA provide higher predictive performance of CI-CVD.

Intracranial atherosclerotic disease and neurodegeneration: a narrative review and plausible mechanisms

INTRODUCTION

Intracranial atherosclerotic disease (ICAD) of the large cerebral arteries, a leading cause of stroke worldwide, is increasingly implicated in cognitive impairment and neurodegeneration among the general population; however, the underlying pathophysiologic mechanisms in this relationship remain unknown.

METHODS

In this narrative review, we aim to provide an overview of the epidemiology and pathophysiology of ICAD, the evidence that relates ICAD to neurodegeneration, putative mechanisms, and future research directions. We synthesized available evidence on PubMed up to August 2024.

RESULTS AND CONCLUSIONS

ICAD, a common cause of stroke, is characterized as a chronic, inflammatory, fibroproliferative disease of the cerebral large arteries. Numerous lines of evidence have related ICAD to clinical, neuroimaging, and pathology-based markers of cognitive impairment and Alzheimer's disease; however, little data exists on plausible pathophysiological links. Based on ongoing and adjacent work, we hypothesize hypoperfusion, arterial stiffness, and inflammation to play a role, but further research is needed. Conventional classification of ICAD often infers from symptomatic coronary artery disease and relies on degree of luminal stenosis, but unique anatomic features of the intracranial circulation may be relevant and a more comprehensive description that includes arterial wall features and plaque morphology may be needed to fully understand its relationship with cognitive impairment and neurodegeneration.

Nomogram for predicting asymptomatic intracranial atherosclerotic stenosis in a neurologically healthy population

Asymptomatic intracranial atherosclerotic stenosis (aICAS) is a major risk factor for cerebrovascular events. The study aims to construct and validate a nomogram for predicting the risk of aICAS. Participants who underwent health examinations at our center from September 2019 to August 2023 were retrospectively enrolled. The participants were randomly divided into a training set and a testing set in a 7:3 ratio. Firstly, in the training set, least absolute shrinkage and selection operator (LASSO) regression and multivariate logistic regression were performed to select variables that were used to establish a nomogram. Then, the receiver operating curves (ROC) and calibration curves were plotted to assess the model's discriminative ability and performance. A total of 2563 neurologically healthy participants were enrolled. According to LASSO-Logistic regression analysis, age, fasting blood glucose (FBG), systolic blood pressure (SBP), hypertension, and carotid atherosclerosis (CAS) were significantly associated with aICAS in the multivariable model (adjusted P < 0.005). The area under the ROC of the training and testing sets was, respectively, 0.78 (95% CI: 0.73-0.82) and 0.65 (95% CI: 0.56-0.73). The calibration curves showed good homogeneity between the predicted and actual values. The nomogram, consisting of age, FBG, SBP, hypertension, and CAS, can accurately predict aICAS risk in a neurologically healthy population.

Intracranial Atherosclerotic Disease and Incident Dementia: The ARIC Study (Atherosclerosis Risk in Communities)

BACKGROUND

Studies of the neurovascular contribution to dementia have largely focused on cerebral small vessel disease (CSVD), but the role of intracranial atherosclerotic disease (ICAD) remains unknown in the general population. The objective of this study was to determine the risk of incident dementia from ICAD after adjusting for CSVD and cardiovascular risk factors in a US community-based cohort.

METHODS

We acquired brain magnetic resonance imaging examinations from 2011 through 2013 in 1980 Black and White participants in the ARIC study (Atherosclerosis Risk in Communities), a prospective cohort conducted in 4 US communities. Magnetic resonance imaging examinations included high-resolution vessel wall magnetic resonance imaging and magnetic resonance angiography to identify ICAD. Of these participants, 1590 without dementia, without missing covariates, and with adequate magnetic resonance image quality were followed through 2019 for incident dementia. Associations between ICAD and incident dementia were assessed using Cox proportional hazard ratios adjusted for CSVD (characterized by white matter hyperintensities, lacunar infarctions, and microhemorrhages), APOE4 genotype (apolipoprotein E gene ε4), and cardiovascular risk factors.

RESULTS

The mean age (SD) of study participants was 77.4 (5.2) years. ICAD was detected in 34.6% of participants. After a median follow-up of 5.6 years, 286 participants developed dementia. Compared with participants without ICAD, the fully adjusted hazard ratios (95% CIs) for incident dementia in participants with any ICAD, with ICAD only causing stenosis ≤50%, and with ICAD causing stenosis >50% in ≥1 vessel were 1.57 (1.17-2.11), 1.41 (1.02-1.95), and 1.94 (1.32-2.84), respectively. ICAD was associated with dementia even among participants with low white matter hyperintensities burden, a marker of CSVD.

CONCLUSIONS

ICAD was associated with an increased risk of incident dementia, independent of CSVD, APOE4 genotype, and cardiovascular risk factors. The increased risk of dementia was evident even among participants with low CSVD burden, a group less likely to be affected by vascular dementia, and in participants with ICAD causing only low-grade stenosis. Our results suggest that ICAD may partially mediate the effect that cardiovascular risk factors have on the brain leading to dementia. Both ICAD and CSVD must be considered to understand the vascular contributions to cognitive decline.

Effects of intracranial artery stenosis of anterior circulation on cognition-A CT perfusion-based study

BACKGROUND

Intracranial atherosclerotic stenosis (ICAS) is one of the most important independent risk factors for stroke that is closely related to the occurrence of cognitive impairment. The relationship between ICAS and vascular cognitive impairment (VCI) remains unclear. Cerebral hemodynamic changes are one of the main causes of cognitive impairment. Computed tomographic perfusion (CTP) imaging can quantitatively analyze cerebral blood perfusion and quantify cerebral hemodynamic changes. Previous research on the relationship between hypoperfusion induced by ICAS and cognitive impairment, as well as its underlying mechanisms, remains relatively insufficient. This study is dedicated to elucidating the characteristics and potential mechanisms of cognitive impairment in ICAS patients with abnormal perfusion, utilizing CTP imaging as our primary investigative tool.

METHODS

This study recruited 82 patients who suffer from non-disabling ischemic stroke (IS group) and 28 healthy controls. All participants underwent comprehensive neuropsychological assessments both collectively and individually, in addition to CTP imaging. Within the patient group, we further categorized individuals into two subgroups: the ischemic penumbra group (IP, N = 28) and the benign oligemia group (BO, N = 54), based on CTP parameters-Tmax. The correlations between cognitive function and abnormal perfusion were explored.

RESULTS

The cognitive function, including the overall cognitive, memory, attention, executive functions, and language, was significantly impaired in the IS group compared with that in the control group. Further, there are statistical differences in the stroop color-word test-dot (Stroop-D) and Montreal Cognitive Assessment (MoCA) sub-items (memory + language) between the BO and IP groups. In the BO group, the score of Stroop-D is lower, and the MoCA sub-items are higher than the IP group. There is no correlation between CTP parameters and cognitive function.

CONCLUSION

Cognitive function is significantly impaired in patients with ICAS, which is related to cerebral perfusion. Executive, memory, and language function were better preserved in ICAS patients without IP. Hence, this study posits that managing hypoperfusion induced by ICAS may play a pivotal role in the development of VCI.

Small-Vessel Disease and Intracranial Large Artery Disease in Brain MRI Predict Dementia and Acute Coronary Syndrome, Respectively: A Prospective, Observational Study in the Population at High Vascular Risk

BACKGROUND

We aimed to clarify the predictive value of cerebral small-vessel disease and intracranial large artery disease (LAD) observed in magnetic resonance imaging of the brain and magnetic resonance angiography on future vascular events and cognitive impairment.

METHODS AND RESULTS

Data were derived from a Japanese cohort with evidence of cerebral vessel disease on magnetic resonance imaging. This study included 862 participants who underwent magnetic resonance angiography after excluding patients with a modified Rankin Scale score >1 and Mini-Mental State Examination score <24. We evaluated small-vessel disease such as white matter hyperintensities and lacunes in magnetic resonance imaging and LAD with magnetic resonance angiography. Outcomes were incident stroke, dementia, acute coronary syndrome, and all-cause death. Over a median follow-up period of 4.5 years, 54 incident stroke, 39 cases of dementia, and 27 cases of acute coronary syndrome were documented. Both small-vessel disease (white matter hyperintensities and lacunes) and LAD were associated with stroke; however, only white matter hyperintensities were related to dementia. In contrast, only LAD was associated with acute coronary syndrome. Among the 357 patients with no prior history of stroke, coronary or peripheral artery disease, or atrial fibrillation, white matter hyperintensities emerged as the sole predictor of future stroke and dementia, while LAD was the sole predictor of acute coronary syndrome.

CONCLUSIONS

Among cerebral vessels, small-vessel disease could underlie the cognitive impairment while LAD was associated with coronary artery disease as atherosclerotic vessel disease.

FFCM-MRF: An accurate and generalizable cerebrovascular segmentation pipeline for humans and rhesus monkeys based on TOF-MRA

PURPOSE

Cerebrovascular segmentation and quantification of vascular morphological features in humans and rhesus monkeys are essential for prevention, diagnosis, and treatment of brain diseases. However, current automated whole-brain vessel segmentation methods are often not generalizable to independent datasets, limiting their usefulness in real-world environments with their heterogeneity in participants, scanners, and species.

MATERIALS AND METHODS

In this study, we proposed an automated, accurate and generalizable segmentation method for magnetic resonance angiography images called FFCM-MRF. This method integrated fast fuzzy c-means clustering and Markov random field optimization by vessel shape priors and spatial constraints. We used a total of 123 human and 44 macaque MRA images scanned at 1.5 T, 3 T, and 7 T MRI from 9 datasets to develop and validate the method.

RESULTS

FFCM-MRF achieved average Dice similarity coefficients ranging from 69.16 % to 89.63 % across multiple independent datasets, with improvements ranging from 3.24 % to 7.3 % compared to state-of-the-art methods. Quantitative analysis showed that FFCM-MRF can accurately segment major arteries in the Circle of Willis at the base of the brain and small distal pial arteries while effectively reducing noise. Test-retest analysis showed that the model yielded high vascular volume and diameter reliability.

CONCLUSIONS

Our results have demonstrated that FFCM-MRF is highly accurate and reliable and largely independent of variations in field strength, scanner platforms, acquisition parameters, and species. The macaque MRA data and user-friendly open-source toolbox are freely available at OpenNeuro and GitHub to facilitate studies of imaging biomarkers for cerebrovascular and neurodegenerative diseases.

Intracranial Atherosclerosis Disease Associated With Cognitive Impairment and Dementia: Systematic Review and Meta-Analysis

BACKGROUND

Intracranial atherosclerosis disease (ICAD) alters cerebrovascular hemodynamics and brain structural integrity. Multiple studies have evaluated the link between ICAD and cognitive impairment, with mixed results. This study aims to systematically review and summarize the current evidence on this link.

METHODS AND RESULTS

PubMed, EMBASE, PsycInfo, and Web of Science were searched from 2000 to 2023 without language restriction. Cross-sectional and prospective cohort studies as well as postmortem studies were included. Studies containing data on the link between ICAD, defined as at least 50% stenosis in 1 intracranial vessel, and cognitive impairment and dementia were screened by 2 independent reviewers. A total of 22 (17 observational and 5 postmortem) unique studies, comprising 11 184 individuals (average age range, 59.8-87.6 years; 45.7% women; 36.5% Asian race), were included in the systematic review. Seven of 10 cross-sectional studies and 5 of 7 prospective studies showed a significant association between ICAD and cognitive impairment. In the pooled analysis, ICAD was associated with greater cognitive impairment (measure of association, 1.87 [95% CI, 1.49-2.35]). Meta-regression analyses did not show a significant impact of age, sex, and race. All postmortem studies showed that patients with Alzheimer disease and vascular dementia had a higher burden of ICAD compared with controls.

CONCLUSIONS

This study shows that ICAD is associated with cognitive impairment and dementia across age, sex, and race groups. Our findings may underscore the need to develop individualized dementia preventive care plans in patients with ICAD.

Intracranial Atherosclerotic Stenosis Is Associated with Cognitive Impairment in Patients with Nondisabling Ischemic Stroke: A pCASL-Based Study

Background: Intracranial atherosclerotic stenosis (ICAS) is a key risk factor for vascular cognitive impairment. Cerebral blood flow (CBF) and the spatial coefficient of variation (sCoV) of CBF images (based on pseudocontinuous arterial spin labeling) are used to explore abnormal cerebral perfusion. We aimed to probe the mechanisms underlying cognitive impairment in patients with nondisabling anterior circulation macrovascular disease. Methods: This study included 47 patients with ICAS or occlusion and 40 controls. All participants underwent global and individual neuropsychology assessments and magnetic resonance imaging scan. The correlations between cognitive function and abnormal perfusion were explored. Results: The CBF in the ipsilateral middle cerebral artery (MCA) territory of the lesion side decreased significantly, while it increased on the contralateral side. CBF value had a significant correlation with the memory function in the right cerebral artery lesion group. The sCoV in both gray matter (GM) and the ipsilateral MCA territory of the lesion increased significantly. The sCoV value based on the GM territory or MCA territory was significantly correlated with global cognitive function, memory function, and executive function in patients with ICAS. Conclusions: The cognitive function of patients with severe ICAS or occlusion in anterior circulation was significantly impaired. sCoV could be a better indicator of cognitive impairment than CBF. Interventions to relieve vascular stenosis or occlusion and delay cognitive impairment or improve cognitive function should be actively considered.

Association between intracranial vessel calcifications, structural brain damage, and cognitive impairment after minor strokes: a prospective study

Background

Vascular calcifications are a hallmark of atherosclerosis, and in the coronary arteries are routinely used as a prognostic marker. Calcifications of intracranial vessels (ICC) are frequently observed on non-contrast CT (NCCT) and their effect on post-stroke cognitive impairment (PSCI) remains unclear. Our aim was to explore the association of ICC with prospective long-term cognitive function and advanced MRI-measures in a large prospective cohort of cognitively intact mild stroke survivors.

Methods

Data from the Tel-Aviv brain acute stroke cohort (TABASCO) study [ClinicalTrials.gov #NCT01926691] were analyzed. This prospective cohort study (n = 575) aimed to identify predictors of PSCI, in cognitively intact mild stroke survivors. A quantitative assessment of the intracranial calcium content - The ICC score (ICCS) was calculated semi-automatically on NCCT using a validated calcium quantification application. Participants underwent a 3 T-MRI and prospective comprehensive cognitive clinical and laboratory assessments at enrollment, 6, 12, and 24-months.

Results

Data were available for 531 participants (67.4 years, 59.5% males). The incidence of PSCI at two-years doubled in the high ICCS group (26% vs. 13.7%, p < 0.001). The high ICCS group had significantly greater small-vessel-disease (SVD) tissue changes and reduced microstructural-integrity assessed by Diffusion-Tensor-Imaging (DTI) maps (p < 0.05 for all). In multivariate analysis, a higher ICCS was independently associated with brain atrophy manifested by lower normalized white and gray matter, hippocampal and thalamic volumes (β = -0.178, β = -0.2, β = -0.137, β = -0.157; p < 0.05) and independently predicted PSCI (OR 1.83, 95%CI 1.01-3.35).

Conclusion

Our findings suggest that the ICCS, which is a simple and readily available imaging marker on NCCT, is associated with brain atrophy, microstructural damage, the extent of SVD, and may predict PSCI. This finding has implications for identifying individuals at risk for PSCI and implementing targeted interventions to mitigate this risk.

Longitudinal real world correlation study of blood pressure and novel features of cerebral magnetic resonance angiography by artificial intelligence analysis on elderly cognitive impairment

Objective

This study aims to investigate novel clinical risk factors for cognitive impairment (CI) in elderly.

Methods

A total of 3221 patients (259 patients with CI and 2,962 subjects without CI) were recruited into this nested case-control study who underwent cerebral magnetic resonance angiography (MRA) from 2007 to 2021. All of the clinical data with MRA imaging were recorded followed by standardization processing blindly. The maximum stenosis score of the posterior circulatory artery, including the basilar artery, and bilateral posterior cerebral artery (PCA), was calculated by the cerebral MRA automatic quantitative analysis method. Logistic regression (LR) analysis was used to evaluate the relationship between risk factors and CI. Four machine learning approaches, including LR, decision tree (DT), random forest (RF), and support vector machine (SVM), employing 5-fold cross-validation were used to establish CI predictive models.

Results

After matching with age and gender, 208 CI patients and 208 control subjects were finalized the follow-up (3.46 ± 3.19 years) with mean age at 84.47 ± 6.50 years old. Pulse pressure (PP) in first tertile (<58 mmHg) (OR 0.588, 95% confidence interval (CI): 0.362-0.955) was associated with a decreased risk for CI, and ≥50% stenosis of the left PCA (OR 2.854, 95% CI: 1.387-5.872) was associated with an increased risk for CI after adjusting for body mass index, myocardial infarction, and stroke history. Based on the means of various blood pressure (BP) parameters, the performance of the LR, DT, RF and SVM models accurately predicted CI (AUC 0.740, 0.786, 0.762, and 0.753, respectively) after adding the stenosis score of posterior circulatory artery.

Conclusion

Elderly with low pulse differential pressure may have lower risk for cognitive impairment. The hybrid model combined with the stenosis score of posterior circulatory artery, clinical indicators, and the means of various BP parameters can effectively predict the risk of CI in elderly individuals.

Intracranial artery stenosis is associated with cortical thinning in stroke-free individuals of two longitudinal cohorts

BACKGROUND

We examined the association between asymptomatic intracranial artery stenosis (aICAS) and cortical thickness using brain magnetic resonance morphometry in two cohorts.

METHODS

This cross-sectional study included stroke-free participants from the Northern Manhattan Study (NOMAS) and the National Alzheimer's Coordinating Center (NACC). We represented the predictor aICAS in NOMAS as a continuous global stenosis score reflecting an overall burden of stenosis (possible range 0-44) assessed by magnetic resonance angiography and in NACC as a dichotomous autopsy-determined Circle of Willis (CoW) atherosclerosis (none-mild vs moderate-severe). The primary outcome of interest was total cortical thickness. We analyzed each dataset separately using multivariable linear regression.

RESULTS

The analysis included 1209 NOMAS (46% had any stenosis, 5% had ≥70% stenosis of at least one vessel; stenosis score range 0-11) and 392 NACC (36% moderate-severe CoW atherosclerosis) participants. We found an inverse relationship between stenosis score and total cortical thickness (β-estimate [95% confidence interval (CI)]: -2.98 [-5.85, -0.11]) in adjusted models. We replicated these results in NACC (β-estimate [95% CI]: -0.06 [-0.11, -0.003]). Post-hoc, we segregated stenosis scores by location and only posterior circulation stenosis score was associated with total cortical thickness (anterior β-estimate [95% CI]: -0.90 [-5.16, 3.36], posterior β-estimate [95% CI]: -7.25 [-14.30, -0.20]).

CONCLUSION

We found both radiographically and neuropathologically determined aICAS to be associated with global cortical thinning. Interestingly, posterior circulation stenoses appeared to drive this association with global cortical thinning, raising the possibility of pathophysiologic mechanisms for cortical thinning other than impaired hemodynamics.

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.

eICAB: A novel deep learning pipeline for Circle of Willis multiclass segmentation and analysis

BACKGROUND

The accurate segmentation, labeling and quantification of cerebral blood vessels on MR imaging is important for basic and clinical research, yet results are not generalizable, and often require user intervention. New methods are needed to automate this process.

PURPOSE

To automatically segment, label and quantify Circle of Willis (CW) arteries on Magnetic Resonance Angiography images using deep convolutional neural networks.

MATERIALS AND METHODS

MRA images were pooled from three public and private databases. A total of 116 subjects (mean age 56 years ± 21 [standard deviation]; 72 women) were used to make up the training set (N=101) and the testing set (N=15). In each image, fourteen arterial segments making up or surrounding the CW were manually annotated and validated by a clinical expert. Convolutional neural network (CNN) models were trained on a training set to be finally combined in an ensemble to develop eICAB. Model performances were evaluated using (1) quantitative analysis (dice score on test set) and (2) qualitative analysis (external datasets, N=121). The reliability was assessed using multiple MRAs of healthy participants (ICC of vessel diameters and volumes on test-retest).

RESULTS

Qualitative analysis showed that eICAB correctly predicted the large, medium and small arteries in 99±0.4%, 97±1% and 88±7% of all images, respectively. For quantitative assessment, the average dice score coefficients for the large (ICAs, BA), medium (ACAs, MCAs, PCAs-P2), and small (AComm, PComm, PCAs-P1) vessels were 0.76±0.07, 0.76±0.08 and 0.41±0.27, respectively. These results were similar and, in some cases, statistically better (p<0.05) than inter-expert annotation variability and robust to image SNR. Finally, test-retest analysis showed that the model yielded high diameter and volume reliability (ICC=0.99).

CONCLUSION

We have developed a quick and reliable open-source CNN-based method capable of accurately segmenting and labeling the CW in MRA images. This method is largely independent of image quality. In the future, we foresee this approach as a critical step towards fully automated analysis of MRA databases in basic and clinical research.

The Associations Between Intracranial Stenosis, Brain Amyloid-beta, and Cognition in a Memory Clinic Sample

BACKGROUND

Intracranial stenosis (ICS) and brain amyloid-beta (Aβ) have been associated with cognition and dementia. We aimed to investigate the association between ICS and brain Aβ and their independent and joint associations with cognition.

METHODS

We conducted a cross-sectional study of 185 patients recruited from a memory clinic. ICS was measured on 3-dimensional time-of-flight magnetic resonance angiography and defined as stenosis ≥50%. Brain Aβ was measured with [ 11 C] Pittsburgh compound B-positron emission tomography imaging. Cognition was assessed with a locally validated neuropsychological battery.

RESULTS

A total of 17 (9.2%) patients had ICS, and the mean standardized uptake value ratio was 1.4 (±0.4 SD). ICS was not significantly associated with brain Aβ deposition. ICS was significantly associated with worse global cognition (β: -1.26, 95% CI: -2.25; -0.28, P =0.013), executive function (β: -1.04, 95% CI: -1.86; -0.22, P =0.015) and visuospatial function (β: -1.29, 95% CI: -2.30; -0.27, P =0.015). Moreover, in ICS patients without dementia (n=8), the presence of Aβ was associated with worse performance on visuomotor speed.

CONCLUSIONS

ICS was significantly associated with worse cognition and showed interaction with brain Aβ such that patients with both pathologies performed worse on visuomotor speed specifically in those without dementia. Further studies may clarify if ICS and brain Aβ deposition indeed have a synergistic association with cognition.

The impact of smoking status on cognition and brain morphology in schizophrenia spectrum disorders

BACKGROUND

Cigarette smoking is associated with worse cognition and decreased cortical volume and thickness in healthy cohorts. Chronic cigarette smoking is prevalent in schizophrenia spectrum disorders (SSD), but the effects of smoking status on the brain and cognition in SSD are not clear. This study aimed to understand whether cognitive performance and brain morphology differed between smoking and non-smoking individuals with SSD compared to healthy controls.

METHODS

Data were obtained from the Australian Schizophrenia Research Bank. Cognitive functioning was measured in 299 controls and 455 SSD patients. Cortical volume, thickness and surface area data were analysed from T1-weighted structural scans obtained in a subset of the sample (n = 82 controls, n = 201 SSD). Associations between smoking status (cigarette smoker/non-smoker), cognition and brain morphology were tested using analyses of covariance, including diagnosis as a moderator.

RESULTS

No smoking by diagnosis interactions were evident, and no significant differences were revealed between smokers and non-smokers across any of the variables measured, with the exception of a significantly thinner left posterior cingulate in smokers compared to non-smokers. Several main effects of smoking in the cognitive, volume and thickness analyses were initially significant but did not survive false discovery rate (FDR) correction.

CONCLUSIONS

Despite the general absence of significant FDR-corrected findings, trend-level effects suggest the possibility that subtle smoking-related effects exist but were not uncovered due to low statistical power. An investigation of this topic is encouraged to confirm and expand on our findings.

Diagnostic yield of TOF-MRA for detecting incidental vascular lesions in patients with cognitive impairment: An observational cohort study

Objectives

The role of three-dimensional (3D) TOF-MRA in patients with cognitive impairment is not well established. We evaluated the diagnostic yield of 3D TOF-MRA for detecting incidental extra- or intracranial artery stenosis and intracranial aneurysm in this patient group.

Methods

This retrospective study included patients with cognitive impairment undergoing our brain MRI protocol from January 2013 to February 2020. The diagnostic yield of TOF-MRA for detecting incidental vascular lesions was calculated. Patients with positive TOF-MRA results were reviewed to find whether additional treatment was performed. Logistic regression analysis was conducted to identify the clinical risk factors for positive TOF-MRA findings.

Results

In total, 1,753 patients (mean age, 70.2 ± 10.6 years; 1,044 women) were included; 199 intracranial aneurysms were detected among 162 patients (9.2%, 162/1,753). A 3D TOF-MRA revealed significant artery stenoses (>50% stenosis) in 162 patients (9.2%, 162/1,753). The overall diagnostic yield of TOF-MRA was 16.8% (294/1,753). Among them, 92 patients (31.3%, 92/294) underwent either medical therapy, endovascular intervention, or surgery. In total, eighty-one patients with stenosis were prescribed with either antiplatelet medications or lipid-lowering agent. In total, fifteen patients (aneurysm: 11 patients, stenosis: 4 patients) were further treated with endovascular intervention or surgery. Thus, the “number needed to scan” was 19 for identifying one patient requiring treatment. Multivariate logistic regression analysis showed that being female (odds ratio [OR] 2.05) and old age (OR 1.04) were the independent risk factors for intracranial aneurysm; being male (OR 1.52), old age (OR 1.06), hypertension (OR 1.78), and ischemic heart disease history (OR 2.65) were the independent risk factors for significant artery stenosis.

Conclusions

Our study demonstrated the potential benefit of 3D TOF-MRA, given that it showed high diagnostic yield for detecting vascular lesions in patients with cognitive impairment and the considerable number of these lesions required further treatment. A 3D TOF-MRA may be included in the routine MR protocol for the work-up of this patient population, especially in older patients and patients with vascular risk factors.

Homocysteine Associated With Low Cognitive Function Independent of Asymptomatic Intracranial and Carotid Arteries Stenoses in Chinese Elderly Patients: An Outpatient-Based Cross-Sectional Study

INTRODUCTION

A high homocysteine (Hcy) concentration is correlated with cognitive impairment; however, the exact underlying mechanism is still not fully elucidated. The present study aimed to investigate whether asymptomatic intracranial and carotid arteries stenoses are involved in Hcy-related low cognitive function.

METHODS

This was a cross-sectional study in outpatient clinics. Residents aged ≥60 years, who came to the Stroke and Rehabilitation Clinic of Shandong Provincial Third Hospital in Jinan, Shandong Province from December 2019 to May 2020 to seek consultation due to abnormal transcranial Doppler reports (eg., increased cerebral blood flow velocity) were eligible. Information including demographics, medical history, lifestyle habits were collected. Fasting blood was used to detect total serum homocysteine level (tHcy). Cerebrovascular magnetic resonance angiography and neck vascular ultrasound examination were used to confirm the diagnosis of intracranial and carotid artery stenoses. The Mini-Mental State Examination was used to assess the cognitive function of each participant. Logistic regression was used to evaluate the relationship between tHcy levels and cognitive function.

RESULTS

This study included 236 participants (mean age: 64.0 (SD, 7.5) years, female: 58.1%). Multivariable analyses adjusted for several potential confounders, including creatinine and cardiovascular risk factors, showed that tHcy was associated with carotid artery stenosis (CAS). After adjusting for CAS, ICAS and several potential confounders, the association between tHcy level and low cognitive function remained significant (odds ratio: 1.09, 95% confidence interval: (1.03, 1.16), P = 0.032) .

CONCLUSION

Increased serum tHcy level was associated with low cognitive function independent of asymptomatic intracranial and carotid arteries stenoses.

Resolving inflammatory links between myocardial infarction and vascular dementia

Myocardial infarction is associated with increased risk for vascular dementia. In both myocardial infarction and vascular dementia, there is evidence that elevated inflammatory biomarkers are associated with worsened clinical outcomes. Myocardial infarction leads to a systemic inflammatory response, which may contribute to recruitment or activation of myeloid cells, including monocytes, microglia, and perivascular macrophages, within the central nervous system. However, our understanding of the causative roles for these cells linking cardiac injury to the development and progression of dementia is incomplete. Herein, we provide an overview of inflammatory cellular and molecular links between myocardial infarction and vascular dementia and discuss strategies to resolve inflammation after myocardial infarction to limit neurovascular injury.

The association between carotid intima-media thickness and cognitive performance is affected by intracranial artery stenosis in Chinese elderly people: An outpatient-based study

BACKGROUND AND AIMS

The association between carotid intima-media thickness (cIMT) and cognitive function remains controversial, and whether this relationship is affected by intracranial artery stenosis (ICAS) remains unclear. We investigated these questions among elderly participants who sought health consultations in an outpatient clinic.

METHODS

We conducted a cross-sectional study based on participants from an outpatient clinic, enrolling residents over 60 years of age seeking outpatient services because of abnormal transcranial Doppler reports at Shandong Provincial Third Hospital in Jinan, Shandong province. We performed physical examinations, blood tests, cIMT measurement using carotid ultrasonography, ICAS measurement using brain magnetic resonance angiography scanning, and global cognitive function assessment using the Montreal Cognitive Assessment (MoCA)in the outpatient clinic from May 2020 to December 2020. We subsequently performed a regression analysis to explore the relationship between cIMT and cognitive function and a stratified analysis to explore whether the relationship was different between the ICAS and non-ICAS participants.

RESULTS

In total, 167 participants (age: 65.56 ± 10.39 years, female: 53.89%) were included in the present study. The MoCA score was significantly lower in the intimal thickening group (cIMT ≥ 1.0 mm) than in the normal group (mean [SD]: 16.23 [5.16] vs. 19.97 [4.59], P < 0.001). Univariate analysis showed that a greater cIMT was negatively correlated with cognitive function. After adjustment for several potential confounders in the multivariable analyses, the association between cIMT and cognitive function disappeared. When further stratified by ICAS, a negative association between increased cIMT (cIMT ≥ 1.0 mm) and cognitive function was found in those without ICAS (β: -2.80 [-5.13, -0.48], p = 0.021); however, in subjects with ICAS, the relationship between cIMT and cognitive function was insignificant.

CONCLUSION

Greater cIMT was associated with low cognitive function in participants without ICAS who sought consultation due to abnormal transcranial Doppler reports in outpatient clinics.

Neutrophil-to-Lymphocyte Ratio as a Predictive Biomarker for Stroke Severity and Short-Term Prognosis in Acute Ischemic Stroke With Intracranial Atherosclerotic Stenosis

Background: Neutrophil-to-lymphocyte ratio (NLR) is an indicator of poor prognosis in acute ischemic stroke (AIS), but associations between NLR with stroke severity and prognosis of intracranial atherosclerotic stenosis (ICAS)-related ischemic events have not been well-elucidated; therefore, we aimed to evaluate whether admission NLR levels correlate with the early stroke severity and short-term functional prognosis in patients with symptomatic intracranial atherosclerotic stenosis (sICAS). Methods: This retrospective study enrolled 899 consecutive patients with AIS attributed to ICAS at Xiangya Hospital stroke center between May 2016 and September 2020. The initial stroke severity was rated by the admission National Institutes of Health Stroke Scale (NIHSS) scores, and the short-term prognosis was evaluated using the 14-day modified Rankin Scale (mRS) scores after stroke onset. A severe stroke was defined as NIHSS >8; an unfavorable functional outcome was defined as mRS scores of 3-6. Admission NLR was determined based on circulating neutrophil and lymphocyte counts. Results: The median admission NLR of all patients was 2.80 [interquartile range (IQR), 2.00-4.00]. In univariate analysis, admission NLR was significantly elevated in patients with severe stroke and poor short-term prognosis. After multivariate adjustment, admission NLR levels were significantly correlated with severe stroke [odds ratio (OR), 1.132; 95% confidence interval (95% CI), 1.038-1.234; P = 0.005] and unfavorable short-term prognosis (OR, 1.102; 95% CI, 1.017-1.195; P = 0.018) in Model 1. In Model 2, the highest NLR tertile (≥3.533) remained an independent predictor of severe stroke (OR, 2.736; 95% CI, 1.590-4.708; P < 0.001) and unfavorable functional outcome (OR, 2.165; 95% CI, 1.416-3.311; P < 0.001) compared with the lowest NLR tertile (<2.231). The receiver operating characteristic (ROC) curves showed the predictability of NLR regarding the stroke severity [area under the curve (AUC), 0.659; 95% CI, 0.615-0.703; P < 0.001] and short-term prognosis (AUC, 0.613; 95% CI, 0.575-0.650; P < 0.001). The nomograms were constructed to create the predictive models of the severity and short-term outcome of sICAS. Conclusions: Elevated admission NLR levels were independently associated with the initial stroke severity and could be an early predictor of severity and poor short-term prognosis in AIS patients with ICAS, which might help us identify a target group timely for preventive therapies.

Intracranial Atherosclerotic Stenosis is Related to Post-stroke Cognitive Impairment: A Cross-sectional Study of Minor Stroke

BACKGROUND

Intracranial Atherosclerotic Stenosis (ICAS) is an important risk factor for cognitive impairment. However, it is unclear whether patients with ICAS are more likely to develop cognitive impairment after an acute, non-disabling ischemic stroke (minor stroke).

OBJECTIVE

We aimed to investigate the association between ICAS and post-stroke cognitive impairment.

METHODS

In this cross-sectional study, patients with acute, non-disabling ischemic stroke underwent two cognitive tests and imaging evaluation for ICAS, within two weeks after the stroke. To determine the association between ICAS and post-stroke cognitive impairment, we performed a multivariate logistic regression analysis adjusted for several demographic and vascular risk factors.

RESULTS

Of the 164 patients with minor stroke in this study, 98 (59.76%) were diagnosed with poststroke cognitive impairment (Montreal Cognitive Assessment score<26). After adjusting for potential confounders, we found that patients with ICAS were more likely to develop cognitive impairment after an acute, non-disabling ischemic stroke, compared to patients without ICAS (Odds Ratio: 2.13; 95% Confidence Interval: 1.07-4.26), and underperformed in the tests of visuospatial and executive function.

CONCLUSION

In this cross-sectional study of a population that has experienced a minor stroke, our findings demonstrated a positive association between ICAS and post-stroke cognitive impairment.

MRI Markers of Mixed Pathology and Cognitive Impairment in Multiethnic Asians

There is a need to elucidate the combined influence of neurodegeneration and cerebrovascular disease (CeVD) on cognitive impairment, especially in diverse populations. Here, we evaluated 840 multiethnic individuals (mean age = 70.18) across the disease spectrum from the Epidemiology of Dementia in Singapore study. First, we determined whether a validated quantitative MRI score of mixed pathology is associated with clinical diagnosis and whether the score differed between ethnicities (Chinese, Malays, and Indians). We then evaluated whether the score was associated with multidomain cognitive impairment and if additional measures of CeVD were further associated with cognitive impairment. We found that lower quantitative MRI scores were associated with severity of clinical diagnosis and Chinese individuals had the highest quantitative MRI scores, followed by Indians and Malays. Lower quantitative MRI scores were also associated with lower performance in attention, language, visuoconstruction, visuomotor, visual, and verbal memory domains. Lastly, the presence of intracranial stenosis and cortical cerebral microinfarcts, but not cerebral microbleeds, were associated with memory performance beyond quantitative MRI scores. Taken together, our results demonstrate the utility of using multiple MRI markers of neurodegeneration and CeVD for identifying multiethnic Asians with the greatest cognitive impairment due to mixed pathology.

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.

Vascular contributions to cognitive impairment and dementia (VCID): A report from the 2018 National Heart, Lung, and Blood Institute and National Institute of Neurological Disorders and Stroke Workshop

Vascular contributions to cognitive impairment and dementia (VCID) are characterized by the aging neurovascular unit being confronted with and failing to cope with biological insults due to systemic and cerebral vascular disease, proteinopathy including Alzheimer's biology, metabolic disease, or immune response, resulting in cognitive decline. This report summarizes the discussion and recommendations from a working group convened by the National Heart, Lung, and Blood Institute and the National Institute of Neurological Disorders and Stroke to evaluate the state of the field in VCID research, identify research priorities, and foster collaborations. As discussed in this report, advances in understanding the biological mechanisms of VCID across the wide spectrum of pathologies, chronic systemic comorbidities, and other risk factors may lead to potential prevention and new treatment strategies to decrease the burden of dementia. Better understanding of the social determinants of health that affect risks for both vascular disease and VCID could provide insight into strategies to reduce racial and ethnic disparities in VCID.

The Barcelona-Asymptomatic Intracranial Atherosclerosis (AsIA) study: Subclinical cervico-cerebral stenosis and middle cerebral artery pulsatility index as predictors of long-term incident cognitive impairment

BACKGROUND AND AIMS

We aimed to study subclinical non-invasive vascular markers as predictors of incident long-term cognitive impairment in a longitudinal population-based study.

METHODS

The Barcelona-Asymptomatic Intracranial Atherosclerosis (AsIA) study is a population-based study that included a random sample of 933 Caucasian subjects (mean age 66 years, 64% male) with a moderate-high vascular risk and without history of stroke or dementia. Subclinical carotid and intracranial stenosis was assessed at baseline visit by cervical and transcranial color-coded duplex (TCCD) and confirmed by magnetic resonance angiography. Cervico-cerebral stenosis (CCS) was defined as the presence of extra and/or intracranial stenosis >50%. Baseline middle cerebral artery pulsatility index (MCA-PI) was measured bilaterally by TCCD, and mean PI of both sides was considered for analyses. Subjects were followed-up to determine incident long-term cognitive impairment (mild cognitive impairment or dementia).

RESULTS

After a median of 7.16 [6.91-7.75] years of follow-up, 91 subjects (9.7%) developed cognitive impairment, 27 of them mild cognitive impairment, and 64 dementia. Incidence of cognitive impairment was significantly higher among subjects with subclinical CCS (21.4% versus 9% in those without CCS) and among those with mean MCA-PI>1 (13.5% versus 7.4% in those with MCA-PI<1). In multivariate Cox regression analyses, both CCS and MCA-PI>1 were independently associated with incident cognitive impairment with HR of 2.07 [1.11-3.88] and 1.58 [1.02-2.46], respectively.

CONCLUSIONS

Subclinical cervico-cerebral stenosis and higher MCA-PI are non-invasive neurosonological markers of incident long-term cognitive impairment in our population.

Hyperglycemia, duration of diabetes, and intracranial atherosclerotic stenosis by magnetic resonance angiography: The ARIC-NCS study

AIMS

The association of hyperglycemia and duration of diabetes with intracranial atherosclerotic stenosis (ICAS) in the general population is not well documented. We examined whether elevated glucose and longer diabetes duration is independently associated with ICAS in a community-based sample.

METHODS

We cross-sectionally analyzed 1644 participants (age 67-90 years) of the Atherosclerosis Risk in Communities Study who underwent cerebrovascular magnetic resonance angiography in 2011-13. We applied multivariable ordinal logistic regression to evaluate the association of ICAS category ("no stenosis", "stenosis <50%", or "stenosis ≥50%") with glucose or diabetes duration (<10, 10 to 20, and ≥20 years). We also obtained the corresponding odds ratios applying inverse-probability weighting to account for potential selection bias due to attrition.

RESULTS

Compared to non-diabetic participants in the lowest glucose quartile, the weighted odds ratios (95% confidence interval) of higher ICAS category were 1.88 (1.18, 3.00) and 2.01 (1.08, 3.72) for non-diabetic and diabetic participants in the corresponding highest glucose quartile, respectively. We observed significant positive trends of ICAS across diabetes duration categories in unweighted, but not in weighted, analyses.

CONCLUSIONS

Hyperglycemia and longer duration of diabetes were independently associated with ICAS, suggesting the importance of maintaining glycemic control to prevent stroke.

Atrial Fibrillation and Cognitive Impairment: An Associated Burden or Burden by Association?

Growing evidence suggests that atrial fibrillation (AF), in addition to its thromboembolic risk, is a risk factor for cognitive impairment (CI) via several pathways and mechanisms, further contributing to morbidity/mortality. Prior stroke is a contributor to CI, but AF is also associated with CI independently from prior stroke. Silent brain infarctions, microemboli and microbleeds, brain atrophy, cerebral hypoperfusion from widely fluctuating ventricular rates, altered hemostatic function, vascular oxidative stress, and inflammation may all exacerbate CI, particularly in patients with persistent/permanent rather than paroxysmal AF and with increased duration/burden of the arrhythmia. Brain magnetic resonance imaging is an important screening tool in eliciting and monitoring vascular and nonvascular lesions contributing to CI. Evidence is also emerging about the role of genetics in CI development. Anticoagulation and rhythm/rate control strategies may protect against CI preventing or slowing its progression or conversion to dementia, particularly at the early stages when CI may still be a treatable condition. Importantly, AF and CI share many common risk factors. Thus, screening for these 2 conditions and searching for and managing modifiable risk factors and potentially reversible causes for both AF and CI remains an important step toward prevention or amelioration of the impact incurred by these 2 conditions.

The Association Between Coronary Artery Calcification and Subclinical Cerebrovascular Diseases in Men: An Observational Study

Aim: Coronary artery calcification (CAC) is an independent predictor of stroke and dementia, in which subclinical cerebrovascular diseases (SCVDs) play a vital pathogenetic role. However, few studies have described the association between CAC and SCVDs. Therefore, the aim of this study was to assess the clinical relationship between CAC and SCVDs in a healthy Japanese male population.

Methods: In this observational study, 709 men, free of stroke, were sampled from a city in Japan from 2010 to 2014. CAC was scored using the Agatston method. The following SCVDs were assessed using magnetic resonance imaging: intracranial arterial stenosis (ICAS), lacunar infarction, deep and subcortical white matter hyperintensity (DSWMH), periventricular hyperintensity (PVH), and microbleeds. The participants were categorized according to CAC scores as follows: no CAC (0), mild CAC (1–100), and moderate-to-severe CAC (> 100). The adjusted odds ratios of prevalent SCVDs were computed in reference to the no-CAC group using logistic regression.

Results: The mean (standard deviation) age of the participants was 68 (8.4) years. Participants in the moderate-to-severe CAC category showed significantly higher odds of prevalent lacunar infarction, DSWMH, and ICAS in age-adjusted and risk-factor-adjusted models. Microbleeds and PVH, in contrast, did not show any significant associations. The trends for CAC with lacunar infarction, DSWMH, and ICAS were also significant (all P-values for trend ≤ 0.02).

Conclusions: Higher CAC scores were associated with higher odds of lacunar infarction, DSWMH, and ICAS. The presence and degree of CAC may be a useful indicator for SCVDs involving small and large vessels.

Percutaneous Transluminal Angioplasty as Potentially Effective Treatment for Persistent Cognitive Decline due to Intracranial Carotid Artery Stenosis

Objective

We describe a male patient with covert sustained cognitive impairment who underwent endovascular treatment for severe stenosis in the left intracranial internal carotid artery (ICA).

Case Presentation

A 64-year-old man presented with transient dysarthria and dysphagia. Although he was alert, a cognitive evaluation revealed significant dysgraphia and a remarkable reduction in cognitive function. Diffusion-weighted imaging (DWI) revealed scattered high-intensity regions in the watershed area of the left cerebral hemisphere and severe stenosis in the C2 portion of the left ICA. Percutaneous transluminal angioplasty (PTA) was performed; a detailed examination revealed significantly improved cognitive function. One year later, the patient demonstrated further cognitive improvement, without any recurrent stroke.

Conclusions

We consider that patients with severe intracranial stenosis, who have covert cognitive decline without apparent sustained symptoms, might be promising candidates for revascularization. Higher brain function in patients with severe intracranial arterial stenosis should be carefully screened because cognitive decline might not be evident at the time of initial presentation.

The effect of chronic cerebral hypoperfusion on the pathology of Alzheimer's disease: A positron emission tomography study in rats

Cerebrovascular disease is a potential risk factor for Alzheimer's disease (AD). Although acute cerebral hypoperfusion causes neuronal necrosis and infarction, chronic cerebral hypoperfusion induces apoptosis in neurons, but its effects on the cognitive impairment are not clear. The purpose of this study was to evaluate the effects of chronic cerebral hypoperfusion on AD pathology and cerebral glucose metabolism. A model of chronic cerebral hypoperfusion was established by ligating the common carotid arteries bilaterally in adult male rats (CAL group). Sham-operated rats underwent the same procedures without artery ligation (control group). At 12 weeks after ligation, expression levels of amyloid-β (Aβ) and hyperphosphorylated tau (p-tau), as well as the regional cerebral glucose metabolism, were evaluated using Western blots and positron emission tomography with fluorine-18 fluorodeoxyglucose, respectively. The expression levels of Aβ in the frontal cortex and hippocampus and of p-tau in the temporal cortex were significantly higher in the CAL group than those in the control group. The cerebral glucose metabolism of the amygdala, entorhinal cortex, and hippocampus was significantly decreased in the CAL group compared to that in the control. These results suggest that chronic cerebral hypoperfusion can induce AD pathology and may play a significant role in AD development.

Progression in Vascular Cognitive Impairment: Pathogenesis, Neuroimaging Evaluation, and Treatment

Vascular cognitive impairment (VCI) defines an entire spectrum of neurologic disorders from mild cognitive impairment to dementia caused by cerebral vascular disease. The pathogenesis of VCI includes ischemic factors (e.g., large vessel occlusion and small vessel dysfunction); hemorrhagic factors (e.g., intracerebral hemorrhage and subarachnoid hemorrhage); and other factors (combined with Alzheimer's disease). Clinical evaluations of VCI mainly refer to neuropsychological testing and imaging assessments, including structural and functional neuroimaging, with different advantages. At present, the main treatment for VCI focuses on neurological protection, cerebral blood flow reconstruction, and neurological rehabilitation, such as pharmacological treatment, revascularization, and cognitive training. In this review, we discuss the pathogenesis, neuroimaging evaluation, and treatment of VCI.