The correlation of asymmetrical functional connectivity with cognition and reperfusion in carotid stenosis patients

Changes in Cognitive Functions after Carotid Endarterectomy and Carotid Stenting: A Decade-Apart Comparison

BACKGROUND

This study investigates changes in cognitive function in patients with severe carotid stenosis who underwent carotid endarterectomy (CEA) and carotid stenting (CAS) over two decades.

METHODS

We compared cognitive function within 30 days after the procedure in 267 patients (first 100 each for CEA and CAS in two periods: 2008-2012 and 2018-2022) in a single institution. Assessments used Adenbrooke's Cognitive Examination-Revised (ACE-R), the Mini-Mental State Examination (MMSE), Speech Fluency Test (SFT), and Clock Drawing Test (CDT), conducted before and 30 ± 2 days after surgery.

RESULTS

Patients (mean age 67.2 years, 70%+ carotid stenosis) exhibited different cognitive changes over periods. In 2008-2012, significant declines in MMSE (CEA, p = 0.049) and CDT (CAS, p = 0.015) were observed among asymptomatic patients. On the contrary, in 2018-2022, improvements were observed in ACE-R and MMSE for symptomatic and asymptomatic patients undergoing CEA and CAS.

CONCLUSION

Over a decade, advances in interventional techniques and patient management have reduced risks of cognitive decline in patients with asymptomatic carotid stenosis and also have improved cognitive functions in both symptomatic and asymptomatic individuals.

Cognitive functions and sense of coherence in patients with carotid artery stenosis-Preliminary report

Background

There is scarcely any data in the available literature on the relationship between sense of coherence (SOC) and cognitive functioning, and no information on the relationship between SOC and cognitive parameters in patients with carotid atherosclerosis.

Aim

The aim of this paper was to determine the relationship of SOC measured prior to carotid artery stenting (CAS) with neurocognitive functioning in patients with carotid atherosclerosis 12 months after CAS.

Methods

A total of 35 patients with carotid atherosclerosis completed the SOC-29 Orientation to Life Questionnaire (SOC-29) and completed a cognitive test battery twice, i.e., before (baseline-T1) and 12 months after stent implantation (follow-up-T2). Selected cognitive functions such as memory, attention, perception, visuospatial and executive functions and non-verbal fluency were assessed.

Results

One year after the procedure, patients with a higher SOC and sense of manageability present better performance in visual memory. Higher SOC and sense of meaningfulness are positively related to the speed of understanding the changing rules of card sorting (WCST).

Conclusion

Higher overall SOC and a component of sense of meaningfulness and manageability may be related to better cognitive functioning 1 year after the procedure.

Neuroimaging anomalies in asymptomatic middle cerebral artery steno-occlusive disease with normal-appearing white matter

Background

Asymptomatic chronic cerebrovascular steno-occlusive disease is common, but the cognitive function and alterations in the brain's structural and functional profiles have not been well studied. This study aimed to reveal whether and how patients with asymptomatic middle cerebral artery (MCA) steno-occlusive disease and normal-appearing white matter differ in brain structural and functional profiles from normal controls and their correlations with cognitive function.

Methods

In all, 26 patients with asymptomatic MCA steno-occlusive disease and 22 healthy controls were compared for neurobehavioral assessments, brain volume, cortical thickness, fiber connectivity density (FiCD) value, and resting-state functional connectivity (FC) using multimodal MRI. We also investigated the associations between abnormal cortical thicknesses, FiCD values, and functional connectivities with the neurobehavioral assessments.

Results

Patients performed worse on memory tasks (Auditory Verbal Learning Test-Huashan version) compared with healthy controls. Patients were divided into two groups: the right group (patients with right MCA steno-occlusive disease) and the left group (patients with left MCA steno-occlusive disease). The left group showed significant cortical thinning in the left superior parietal lobule, while the right group showed significant cortical thinning in the right superior parietal lobule and caudal portion of the right middle frontal gyrus. Increased FiCD values in the superior frontal region of the left hemisphere were observed in the left group. In addition, a set of interhemispheric and intrahemispheric FC showed a significant decrease or increase in both the left and right groups. Many functional connectivity profiles were positively correlated with cognitive scores. No correlation was found between cortical thickness, FiCD values, and cognitive scores.

Conclusion

Even if the patients with MCA steno-occlusive disease were asymptomatic and had normal-appearing white matter, their cognitive function and structural and functional profiles had changed, especially the FC. Alterations in FC may be an important mechanism underlying the neurodegenerative process in patients with asymptomatic MCA steno-occlusive disease before structural changes occur, so FC assessment may promote the detection of network alterations, which may be used as a biomarker of disease progression and therapeutic efficacy evaluation in these patients.

Asymptomatic carotid stenosis is associated with both edge and network reconfigurations identified by single-subject cortical thickness networks

Background and purpose

Patients with asymptomatic carotid stenosis, even without stroke, are at high risk for cognitive impairment, and the neuroanatomical basis remains unclear. Using a novel edge-centric structural connectivity (eSC) analysis from individualized single-subject cortical thickness networks, we aimed to examine eSC and network measures in severe (> 70%) asymptomatic carotid stenosis (SACS).

Methods

Twenty-four SACS patients and 24 demographically- and comorbidities-matched controls were included, and structural MRI and multidomain cognitive data were acquired. Individual eSC was estimated via the Manhattan distances of pairwise cortical thickness histograms.

Results

In the eSC analysis, SACS patients showed longer interhemispheric but shorter intrahemispheric Manhattan distances seeding from left lateral temporal regions; in network analysis the SACS patients had a decreased system segregation paralleling with white matter hyperintensity burden and recall memory. Further network-based statistic analysis identified several eSC and subgraph features centred around the Perisylvian regions that predicted silent lesion load and cognitive tests.

Conclusion

We conclude that SACS exhibits abnormal eSC and a less-optimized trade-off between physical cost and network segregation, providing a reference and perspective for identifying high-risk individuals.

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 dementia^1,2. 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.

Mediating roles of leukoaraiosis and infarcts in the effects of unilateral carotid artery stenosis on cognition

Background and objectives

Leukoaraiosis and infarcts are common in patients with carotid artery stenosis (CAS), and CAS severity, leukoaraiosis and infarcts all have been implicated in cognitive impairments. CAS severity was not only hypothesized to directly impede specific cognitive domains, but also transmit its effects indirectly to cognitive function through ipsilateral infarcts as well as periventricular leukoaraiosis (PVL) and deep white matter leukoaraiosis (DWML). We aimed to delineate the contributions of leukoaraiosis, infarcts and CAS to different specific cognitive domains.

Materials and methods

One hundred and sixty one participants with unilateral CAS (>50%) on the left (n = 85) or right (n = 76) side and 65 volunteers without significant CAS (<50%) were recruited. The PVL, DWML, and infarct severity were visually rated on MRI. A comprehensive cognitive battery was administered and standardized based on age norms. Correlation and mediation analyses were adopted to examine the direct and indirect influence of CAS, leukoaraiosis, and infarct on specific cognitive domains with adjustment for education, hypertension, diabetes mellitus, and hyperlipidemia.

Results

Carotid artery stenosis severity was associated with ipsilateral leukoaraiosis and infarct. Left CAS had direct effects on most cognitive domains, except for visual memory and constructional ability, and transmitted its indirect effects on all cognitive domains through ipsilateral PVL, and on constructional ability and psychomotor through infarcts. Right CAS only had negative direct effects on visual memory, psychomotor, design fluency and color processing speed, and transmitted its indirect effects on visual memory, word and color processing speed through ipsilateral infarcts. The trends of direct and indirect cognitive effects remained similar after covariate adjustment.

Conclusion

Left and right CAS would predominantly lead to verbal and non-verbal cognitive impairment respectively, and such effects could be mediated through CAS-related leukoaraiosis and infarct. Given that cognition is subject to heterogeneous pathologies, the exact relationships between markers of large and small vessel diseases and their composite prognostic effects on cognition requires further investigation.

Brain alterations of regional homogeneity, degree centrality, and functional connectivity in vulnerable carotid plaque patients with neither clinical symptoms nor routine MRI lesions: A resting-state fMRI study

Aims

Based on resting-state functional MRI (fMRI), we preliminarily explored brain alterations in asymptomatic patients with vulnerable carotid plaques, but carotid stenosis was < 50%.

Methods

A total of 58 asymptomatic patients with vulnerable carotid plaques (stenosis <50%) and 38 healthy controls were recruited. Between-group differences in regional homogeneity (ReHo), degree centrality (DC), and functional connectivity (FC) were analyzed. Correlation analysis was performed between the ReHo or DC values in altered brain regions as well as voxel-wise abnormal FC and scores on neuropsychiatric scales, serum interleukin-6 (IL-6), and C-reactive protein (CRP).

Results

Both ReHo and DC values on the left superior occipital gyrus (SOG.L) of the asymptomatic vulnerable carotid plaque group reduced, regardless of plaque location (left, right, or bilateral). Functional connections weakened between the SOG.L and right lingual gyrus (LING.R)/right inferior occipital gyrus (IOG.R), right middle frontal gyrus (MFG.R)/orbital part of superior frontal gyrus (ORBsup.R)/orbital part of middle frontal gyrus (ORBmid.R), left precentral gyrus (PreCG.L)/postcentral gyrus (PoCG.L), left supplementary motor area (SMA.L), right paracentral lobule (PCL.R), left precuneus (PCUN.L), and right postcentral gyrus (PoCG.R)/PCL.R. In ReHo-altered brain regions, ReHo values were positively correlated with Hamilton Rating Scale for Depression (HAMD) scores, and the setting region of abnormal ReHo as seed points, voxel-wise FC between the SOG.L and PreCG.L was negatively correlated with CRP.

Conclusions

Cerebral alterations of neuronal synchronization, activity, and connectivity properties in the asymptomatic vulnerable carotid plaque group were independent of the laterality of vulnerable carotid plaques. Significant relation between ReHo values on the SOG.L and HAMD indicated that even when there were neither clinical symptoms nor lesions on routine MRI, brain function might have changed already at an early stage of carotid atherosclerosis. Inflammation might play a role in linking vulnerable carotid plaques and changes of resting-state functional connectivity.

Cognitive Functions after Carotid Artery Stenting-1-Year Follow-Up Study

Background: The revascularization of carotid arteries minimizes the risk of future cerebral stroke and usually improves cognitive functions. The aim of this study was to assess changes in cognitive function and verify the hypothesis assuming an improvement of selected cognitive functions—psychomotor speed, visuospatial episodic memory, executive function and verbal fluency—in patients after carotid artery stenting during a 12-month follow-up. Methods: 47 persons subject to CAS, including 13 symptomatic persons, were examined before and 12 months after a procedure with a psychological test battery (digit symbol test—DS, Rey–Osterrieth complex figure test—ROCF, Wisconsin Card Sorting Test—WCST, letter verbal fluency—LVF). Sociodemographic data and clinical parameters were acquired from an author questionnaire. Results: The one-year follow-up, after the performed CAS procedure, demonstrated a significant improvement of psychomotor speed, visuospatial episodic memory, and executive function. No changes in the area of verbal fluency or decline in any of cognitive functions under analysis were observed. Conclusions: Carotid artery stenting improves cognitive functioning, both in the area of basic and more complex cognitive functions in persons with carotid atherosclerosis.

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.

Functional MRI evaluation of cognitive effects of carotid stenosis revascularization

INTRODUCTION

Severe internal carotid stenosis, if left untreated, can pose serious risks for ischemic stroke and cognitive impairments. The effects of revascularization on any aspects of cognition, however, are not well understood, as conflicting results are reported, which have mainly been centered on paper-based cognitive analyses. Here, we summarized and evaluated the publications to date of functional MRI (fMRI) studies that examined the mechanisms of functional brain activation and connectivity as a way to reflect cognitive effects of revascularization on patients with carotid stenosis.

METHODS

A PubMed and Google Scholar (covering the relevant literature until November 1, 2021) search yielded eight original studies of the research line, including seven resting-state and one task-based fMRI reports.

RESULTS

Findings demonstrated treatment-related alterations in fMRI signal intensity and symmetry level, regional fMRI activation pattern, and functional brain network connectivity. The functional brain changes were associated largely with improvement in cognitive function assessed using standard cognitive test scores.

CONCLUSIONS

These findings support the contribution of fMRI to the understanding of brain functional activation and connectivity changes revealing cognitive effects of revascularization in the management of severe carotid stenosis. The review also highlighted the importance of reproducibility through enhancing experimental designs and cognitive task applications with future research for potential clinical translation.

Cognitive Sequelae of Silent Ischemic Lesions Following Carotid Artery Stenting: Possible Role of Age-Related Moderation

Background: The occurrence of ischemic lesions is common in patients receiving carotid artery stenting (CAS), and most of them are clinically silent. However, few studies have directly addressed the cognitive sequelae of these procedure-related silent ischemic lesions (SILs).

Objective: In this study, we attempted to investigate the effects of SILs on cognition using a comprehensive battery of neuropsychological tests.

Method: Eighty-five patients with unilateral carotid stenosis and 25 age-matched healthy volunteers participated in this study. Brain MRI was performed within 1 week before and 1 week after CAS to monitor the occurrence of post-CAS SILs. A comprehensive battery tapping reading ability, verbal and non-verbal memory, visuospatial function, manual dexterity, executive function, and processing speed was administered 1 week before and 6 months after CAS. To control for practice effects on repeated cognitive testing, the reliable change index (RCI) derived from the healthy volunteers was used to determine the cognitive changes in patients with carotid stenosis.

Results: Among the 85 patients with carotid stenosis, 21 patients received medical treatment (MED group), and procedure-related SILs were noted in 17 patients (SIL+ group) but not observed in 47 patients (SIL– group) after undergoing CAS. Two-way (group × phase) ANOVA revealed that the volunteer group showed improved scores in most cognitive tests while only limited improvement was noted in the SIL– group. The MED and control groups tended to show improvement in the follow-up cognitive testing than the SIL+ group. However, most of the cognitive changes for each patient group did not exceed the upper or lower limits (z = ±1.0) of the RCI.

Conclusions: Although the occurrence of procedure-related SILs is common in patients undergoing CAS, their impacts on cognitive changes after CAS may be limited. The practice effect should be taken into consideration when interpreting cognitive changes following CAS.

Neurodegeneration and Vascular Burden on Cognition After Midlife: A Plasma and Neuroimaging Biomarker Study

Background and Objectives: Neurodegeneration and vascular burden are the two most common causes of post-stroke cognitive impairment. However, the interrelationship between the plasma beta-amyloid (Aβ) and tau protein, cortical atrophy and brain amyloid accumulation on PET imaging in stroke patients is undetermined. We aimed to explore: (1) the relationships of cortical thickness and amyloid burden on PET with plasma Aβ40, Aβ42, tau protein and their composite scores in stroke patients; and (2) the associations of post-stroke cognitive presentations with these plasma and neuroimaging biomarkers.

Methods: The prospective project recruited first-ever ischemic stroke patients around 3 months after stroke onset. The plasma Aβ40, Aβ42, and total tau protein were measured with the immunomagnetic reduction method. Cortical thickness was evaluated on MRI, and cortical amyloid plaque deposition was evaluated by ¹⁸F-florbetapir PET. Cognition was evaluated with Mini-Mental State Examination (MMSE), Geriatric Depression Scale (GDS), Dementia Rating Scale-2 (DRS-2).

Results: The study recruited 24 stroke patients and 13 normal controls. The plasma tau and tau*Aβ42 levels were correlated with mean cortical thickness after age adjustment. The Aβ42/Aβ40 ratio was correlated with global cortical ¹⁸F-florbetapir uptake value. The DRS-2 and GDS scores were associated with mean cortical thickness and plasma biomarkers, including Aβ42/Aβ40, tau, tau*Aβ42, tau/Aβ42, and tau/Aβ40 levels, in stroke patients.

Conclusion: Plasma Aβ, tau, and their composite scores were associated with cognitive performance 3 months after stroke, and these plasma biomarkers were correlated with corresponding imaging biomarkers of neurodegeneration. Further longitudinal studies with a larger sample size are warranted to replicate the study results.

Changes of Brain Functional Connectivity in End-Stage Renal Disease Patients Receiving Peritoneal Dialysis Without Cognitive Decline

Background: Functional connectivity detected by resting-state functional MRI (R-fMRI) helps to discover the subtle changes in brain activities. Patients with end-stage renal disease (ESRD) on hemodialysis (HD) have impaired brain networks. However, the functional changes of brain networks in patients with ESRD undergoing peritoneal dialysis (PD) have not been fully delineated, especially among those with preserved cognitive function. Therefore, it is worth knowing about the brain functional connectivity in patients with PD by using R-fMRI.

Methods: This case-control study prospectively enrolled 19 patients with ESRD receiving PD and 24 age- and sex- matched controls. All participants without a history of cognitive decline received mini-mental status examination (MMSE) and brain 3-T R-fMRI. Comprehensive R-fMRI analyses included graph analysis for connectivity and seed-based correlation networks. Independent t-tests were used for comparing the graph parameters and connectivity networks between patients with PD and controls.

Results: All subjects were cognitively intact (MMSE > 24). Whole-brain connectivity by graph analysis revealed significant differences between the two groups with decreased global efficiency (E_glob, p < 0.05), increased betweenness centrality (BC) (p < 0.01), and increased characteristic path length (L, p < 0.01) in patients with PD. The functional connections of the default-mode network (DMN), sensorimotor network (SMN), salience network (SN), and hippocampal network (HN) were impaired in patients with PD. Meanwhile, in DMN and SN, elevated connectivity was observed in certain brain regions of patients with PD.

Conclusion: Patients with ESRD receiving PD had specific disruptions in functional connectivity. In graph analysis, E_glob, BC, and L showed significant connectivity changes compared to the controls. DMN and SN had the most prominent alterations among the observed networks, with both decreased and increased connectivity regions. Our study confirmed that significant changes in cerebral connections existed in cognitively intact patients with PD.

Cognitive Functions in Patients after Carotid Artery Revascularization-A Narrative Review

Carotid revascularization may lead to improved cognitive function beyond stroke prevention. This article summarizes the conclusions from available studies on the effects of carotid reperfusion procedures on cognitive function. The papers cited used different neuropsychological tests for cognitive assessment, resulting in different methodologies and the results obtained were not always convergent. However, most studies reported an improvement in neurocognitive abilities after both vascular interventions, but a more precise assessment of the specific benefits is still awaited. Clinical determinants to predict the effects of these treatments on cognitive function are still being sought, but results are not yet satisfactory. In view of these studies, carotid stenosis seems to be an independent risk factor for cognitive deterioration, and the main mechanisms responsible are embolism and cerebral hypoperfusion. The aim of this study is to order the knowledge about the effects of carotid artery stenting (CAS) and endarterectomy (CEA) on neurocognitive functions and to verify the usefulness of using these treatments.

Association between metabolic syndrome and resting-state functional brain connectivity

The objective of this study is to examine whether metabolic syndrome (MetS), the clustering of 3 or more cardiovascular risk factors, disrupts the resting-state functional connectivity (FC) of the large-scale cortical brain networks. Resting-state functional magnetic resonance imaging data were collected from seventy-eight middle-aged and older adults living with and without MetS (27 MetS; 51 non-MetS). FC maps were derived from the time series of intrinsic activity in the large-scale brain networks by correlating the spatially averaged time series with all brain voxels using a whole-brain seed-based FC approach. Participants with MetS showed hyperconnectivity across the core brain regions with evidence of loss of modularity when compared with non-MetS individuals. Furthermore, patterns of higher between-network MetS-related effects were observed across most of the seed regions in both right and left hemispheres. These findings indicate that MetS is associated with altered intrinsic communication across core neural networks and disrupted between-network connections across the brain due to the co-occurring vascular risk factors in MetS.

Long-term cognitive and multimodal imaging outcomes after carotid artery stenting vs intensive medication alone for severe asymptomatic carotid stenosis

BACKGROUND

Severe carotid stenosis is associated with cognitive impairment, which may be attributed to asymptomatic microembolism and/or chronic hypoperfusion. We aim to evaluate the long-term cognitive and brain connectivity outcomes of carotid artery stenting (CAS) for asymptomatic ≥70% stenosis of the extracranial internal carotid artery (ICA).

METHODS

We conducted a non-randomized controlled study to compare intensive medical therapy alone (Med) or in combination with carotid artery stenting for the composite vascular events, neuropsychological, and multimodal magnetic resonance perfusion imaging and diffusion tensor imaging outcomes.

RESULTS

Sixty-nine patients were followed for a mean of 2.3 years (31 Med, 38 CAS) and 11 patients had composite vascular events of all-cause death, ischemic stroke, or myocardial infarction (6 Med vs 5 CAS). Forty-six asymptomatic subjects completed neuropsychological and multimodality imaging follow-ups (23 Med, 23 CAS). Compared to the Med group, the CAS group had a modest improvement of 12-item delayed verbal memory (8.9 ± 2.4 to 9.8 ± 2.7 vs 9.0 ± 2.1 to 8.9 ± 2.3, p = 0.04), but not in global cognition, attention or executive function, which was associated with increased structural connectivity of fractional anisotropy at the ipsilateral deep white matter. Importantly, the memory improvement was correlated with the perfusion increment at the ipsilateral middle cerebral artery territory.

CONCLUSION

For asymptomatic extracranial carotid steno-occlusion, successful carotid revascularization in addition to intensive medical treatment may potentially benefit cognitive reserve and connectivity strength which are partly attributed to restoration of non-critical hypoperfusion.

Investigation of reactive astrogliosis effect on post-stroke cognitive impairment

BACKGROUND

The aim of this study is to investigate the associations between post-stroke cognitive impairment (PSCI) severity and reactive astrogliosis (RA) extent on normalized ¹⁸F-THK-5351 positron-emission tomography (PET) imaging in amyloid-negative patients with first-ever stroke.

METHODS

We prospectively enrolled 63 amyloid-negative patients with first-ever stroke. Neurocognitive evaluation, MRI, ¹⁸F-THK-5351, and ¹⁸F-florbetapir PET were performed around 3 months after stroke. The ¹⁸F-THK-5351 uptake intensity was normalized using a signal distribution template to obtain the Z-SUM scores as the RA extent in the whole brain and cerebral hemisphere ipsilateral to stroke lesion. We evaluated stroke volume, leukoaraiosis, and brain atrophy on MRI. We used a comprehensive neurocognitive battery to obtain composite cognitive scores, and defined PSCI as a general cognitive function score < - 1. We analyzed the influence of Z-SUM scores on PSCI severity after adjusting for demographic, vascular, and neurodegenerative variables.

RESULTS

Twenty-five of 63 stroke patients had PSCI. Patients with PSCI had older age, lower education, and more severe cortical atrophy and total Z-SUM scores. Total Z-SUM scores were significantly associated with general cognitive and executive functions at multiple regression models. Path analyses showed that stroke can exert cognitive influence directly by stroke itself as well as indirectly through RA, including total and ipsilateral Z-SUM scores, in patients with either right or left hemisphere stroke.

CONCLUSION

The patterns and intensity of ¹⁸F-THK-5351 uptake in amyloid-negative patients with first-ever stroke were associated with PSCI manifestations, which suggests that RA presents a modulating effect in PSCI development.

Brain Functional Network in Chronic Asymptomatic Carotid Artery Stenosis and Occlusion: Changes and Compensation

Asymptomatic carotid artery stenosis (CAS) and occlusion (CAO) disrupt cerebral hemodynamics. There are few studies on the brain network changes and compensation associated with the progression from chronic CAS to CAO. In the current study, our goal is to improve the understanding of the specific abnormalities and compensatory phenomena associated with the functional connection in patients with CAS and CAO. In this prospective study, 27 patients with CAO, 29 patients with CAS, and 15 healthy controls matched for age, sex, education, handedness, and risk factors underwent neuropsychological testing and resting-state functional magnetic resonance (rs-fMRI) imaging simultaneously; graph theoretical analysis of brain networks was performed to determine the relationship between changes in brain network connectivity and the progression from internal CAS to CAO. The global properties of the brain network assortativity (p = 0.002), hierarchy (p = 0.002), network efficiency (p = 0.011), and small-worldness (p = 0.009) were significantly more abnormal in the CAS group than in the control and CAO groups. In patients with CAS and CAO, the nodal efficiency of key nodes in multiple brain regions decreased, while the affected hemisphere lost many key functional connections. In this study, we found that patients with CAS showed grade reconstruction, invalid connections, and other phenomena that impaired the efficiency of information transmission in the brain network. A compensatory functional connection in the contralateral cerebral hemisphere of patients with CAS and CAO may be an important mechanism that maintains clinical asymptomatic performance. This study not only reveals the compensation mechanism of cerebral hemisphere ischemia but also validates previous explanations for brain function connectivity, which can help provide interventions in advance and reduce the impairment of higher brain functions. This trial is registered with Clinical Trial Registration-URL http://www.chictr.org.cn and Unique identifier ChiCTR1900023610.