White matter lesions, cognition, and recurrent hemorrhage in lobar intracerebral hemorrhage

Neuropathological Correlates of White Matter Hyperintensities in Cerebral Amyloid Angiopathy

BACKGROUND

White matter hyperintensities (WMHs) are frequently observed on magnetic resonance imaging (MRI) in patients with cerebral amyloid angiopathy (CAA). The neuropathological substrates that underlie WMHs in CAA are unclear, and it remains largely unexplored whether the different WMH distribution patterns associated with CAA (posterior confluent and subcortical multispot) reflect alternative pathophysiological mechanisms.

METHODS AND RESULTS

We performed a combined in vivo MRI-ex vivo MRI-neuropathological study in patients with definite CAA. Formalin-fixed hemispheres from 19 patients with CAA, most of whom also had in vivo MRI available, underwent 3T MRI, followed by standard neuropathological examination of the hemispheres and targeted neuropathological assessment of WMH patterns. Ex vivo WMH volume was independently associated with CAA severity (P=0.046) but not with arteriolosclerosis (P=0.743). In targeted neuropathological examination, compared with normal-appearing white matter, posterior confluent WMHs were associated with activated microglia (P=0.043) and clasmatodendrosis (P=0.031), a form of astrocytic injury. Trends were found for an association with white matter rarefaction (P=0.074) and arteriolosclerosis (P=0.094). An exploratory descriptive analysis suggested that the histopathological correlates of WMH multispots were similar to those underlying posterior confluent WMHs.

CONCLUSIONS

This study confirmed that vascular amyloid β severity in the cortex is significantly associated with WMH volume in patients with definite CAA. The histopathological substrates of both posterior confluent and WMH multispots were comparable, suggesting overlapping pathophysiological mechanisms, although these exploratory observations require confirmation in larger studies.

Factors associated with cognitive impairment before intracerebral haemorrhage: community-based neuropathological study

Little is known about whether clinical, radiological or neuropathological features are associated with cognitive impairment before intracerebral haemorrhage. We conducted a community-based cohort study of 125 adults with intracerebral haemorrhage (lobar n = 71, non-lobar n = 54) with consent to brain autopsy. We compared small vessel disease biomarkers on diagnostic CT head and neuropathological findings including neurofibrillary tangles and amyloid plaques in adults without cognitive impairment versus cognitive impairment without dementia versus dementia before intracerebral haemorrhage, stratified by lobar and non-lobar intracerebral haemorrhage. In non-lobar intracerebral haemorrhage, severe cortical atrophy was less common in those without cognitive impairment (8/36, 22%) and cognitive impairment without dementia (0/9, 0%) versus dementia (5/9, 56%); P = 0.008. Irrespective of intracerebral haemorrhage location, adults without cognitive impairment had milder neurofibrillary tangle pathology measured by median Braak stage (lobar intracerebral haemorrhage: no cognitive impairment 2 [interquartile range, 2-3] versus cognitive impairment without dementia 4 [2-6] versus dementia 5.5 [4-6]; P = 0.004; non-lobar intracerebral haemorrhage: no cognitive impairment 2 [1-2] versus cognitive impairment without dementia 2 [1-2] versus dementia 5 [3-6]; P < 0.001). Irrespective of intracerebral haemorrhage location, adults without cognitive impairment had milder amyloid plaque pathology measured by median Thal stage (lobar intracerebral haemorrhage: no cognitive impairment 2 [1-2] versus cognitive impairment without dementia 2 [2-3] versus dementia 2.5 [2-3.5]; P = 0.033; non-lobar intracerebral haemorrhage: no cognitive impairment 1 [0-1] versus cognitive impairment without dementia 0 [0-2] versus dementia 3 [2-3]; P = 0.002). Our findings suggest that irrespective of intracerebral haemorrhage location, adults with cognitive impairment before an intracerebral haemorrhage have more Alzheimer's disease neuropathologic change.

P2Y6 Receptor Activation Aggravates NLRP3-dependent Microglial Pyroptosis via Downregulation of the PI3K/AKT Pathway in a Mouse Model of Intracerebral Hemorrhage

Pro-inflammatory signals generated after intracerebral hemorrhage (ICH) trigger a form of regulated cell death known as pyroptosis in microglia. White matter injury (WMI) refers to the condition where the white matter area of the brain suffers from mechanical, ischemic, metabolic, or inflammatory damage. Although the p2Y purinoceptor 6 (P2Y6R) plays a significant role in the control of inflammatory reactions in central nervous system diseases, its roles in the development of microglial pyroptosis and WMI following ICH remain unclear. In this study, we sought to clarify the role of P2Y6R in microglial pyroptosis and WMI by using an experimental mouse model of ICH. Type IV collagenase was injected into male C57BL/6 mice to induce ICH. Mice were then treated with MRS2578 and LY294002 to inhibit P2Y6R and phosphatidylinositol 3-kinase (PI3K), respectively. Bio-conductivity analysis was performed to examine PI3K/AKT pathway involvement in microglial pyroptosis. Quantitative Real-Time PCR, immunofluorescence staining, and western blot were conducted to examine microglial pyroptosis and WMI following ICH. A modified Garcia test, corner turning test, and forelimb placement test were used to assess neurobehavior. Hematoxylin-eosin staining (HE) was performed to detect cells damage around hematoma. Increases in the expression of P2Y6R, NLRP3, ASC, Caspase-1, and GSDMD were observed after ICH. P2Y6R was only expressed on microglia. MRS2578, a specific inhibitor of P2Y6R, attenuated short-term neurobehavioral deficits, brain edema and hematoma volume while improving both microglial pyroptosis and WMI. These changes were accompanied by decreases in pyroptosis-related proteins and pro-inflammatory cytokines both in vivo and vitro. Bioinformatic analysis revealed an association between the PI3K/AKT pathway and P2Y6R-mediated microglial pyroptosis. The effects of MRS2578 were partially reversed by treatment with LY294002, a specific PI3K inhibitor. P2Y6R inhibition alleviates microglial pyroptosis and WMI and ameliorates neurological deficits through the PI3K/AKT pathway after ICH. Consequently, targeting P2Y6R might be a promising approach for ICH treatment.

A new score for predicting intracranial hemorrhage in patients using antiplatelet drugs

Antiplatelet drugs in patients increase the risk of intracranial hemorrhage (ICH), which can seriously affect patients' quality of life and even endanger their lives. Currently, there is no specific score for predicting the risk of ICH caused by antiplatelet drugs. We aimed to identify factors associated with ICH in patients on antiplatelet drugs and to construct and validate a predictive model that would provide a validated tool for the clinic. Data were obtained from the patient medical records inpatient system. Prediction models were built by logistic regression, the area under the curve (AUC), and column line plots. Internal validation, analytical identification and calibration of the model using AUC, calibration curves and Hosmer-Lemeshow test. The registration number of this study is ChiCTR2000031909, and the ethical review number is 2020KY087. This single-center retrospective study enrolled 753 patients treated with antiplatelet drugs, including 527 in the development cohort. Multifactorial analysis showed that male, headache or vomiting, hypertension, cerebrovascular disease, CT-defined white matter hypodensity, abnormal GCS, fibrinogen and D-dimer were independent risk factors for ICH, and lipid-lowering drugs was a protective factor. The model was constructed using these nine factors with an AUC value of 0.949. In the validation cohort, the model showed good discriminatory power with an AUC value of 0.943 and good calibration (Hosmer-Lemeshow test P value of 0.818). Based on 9 factors, we derived and validated a predictive model for ICH with antiplatelet drugs in patients. The model has good predictive value and may be an effective tool to reduce the occurrence of ICH.

Iron/ROS/Itga3 mediated accelerated depletion of hippocampal neural stem cell pool contributes to cognitive impairment after hemorrhagic stroke

Hemorrhagic stroke, specifically intracerebral hemorrhage (ICH), has been implicated in the development of persistent cognitive impairment, significantly compromising the quality of life for affected individuals. Nevertheless, the precise underlying mechanism remains elusive. Here, we report for the first time that the accumulation of iron within the hippocampus, distal to the site of ICH in the striatum, is causally linked to the observed cognitive impairment with both clinical patient data and animal model. Both susceptibility-weighted imaging (SWI) and quantitative susceptibility mapping (QSM) demonstrated significant iron accumulation in the hippocampus of ICH patients, which is far from the actual hematoma. Logistical regression analysis and multiple linear regression analysis identified iron level as an independent risk factor with a negative correlation with post-ICH cognitive impairment. Using a mouse model of ICH, we demonstrated that iron accumulation triggers an excessive activation of neural stem cells (NSCs). This overactivation subsequently leads to the depletion of the NSC pool, diminished neurogenesis, and the onset of progressive cognitive dysfunction. Mechanistically, iron accumulation elevated the levels of reactive oxygen species (ROS), which downregulated the expression of Itga3. Notably, pharmacological chelation of iron accumulation or scavenger of aberrant ROS levels, as well as conditionally overexpressed Itga3 in NSCs, remarkably attenuated the exhaustion of NSC pool, abnormal neurogenesis and cognitive decline in the mouse model of ICH. Together, these results provide molecular insights into ICH-induced cognitive impairment, shedding light on the value of maintaining NSC pool in preventing cognitive dysfunction in patients with hemorrhagic stroke or related conditions.

Brain MRI microbleeds and risk of intracranial hemorrhage in atrial fibrillation patients: A Swedish case-control study

OBJECTIVES

Our goal was to quantify the independent association of brain microbleeds with future intracranial hemorrhage (ICrH). Microbleed findings on brain magnetic resonance imaging (MRI) may identify distinctive risk factors for ICrH which could inform the anticoagulant therapy decision for atrial fibrillation (AF) patients. Our study design includes patients with MRIs for numerous reasons, not limited to evaluation of stroke.

MATERIALS AND METHODS

The source population was all patients with AF from a nationwide Swedish health care register. Case patients had an ICrH between 2006 and 2013 and ≥1 brain MRI for an unrelated condition before the ICrH. Each case was matched to four controls who had a brain MRI without a subsequent ICrH. The MRIs were re-reviewed by neuroradiologists. Associations between MRI findings and subsequent ICrH were assessed using logistic regression, adjusting for comorbidities and antithrombotic medications.

RESULTS

A total of 78 cases and 312 matched controls were identified; 29 cases and 79 controls had MRI sequences suitable for analysis of microbleeds. Patients with ≥10 microbleeds had a markedly increased risk of ICrH (adjusted odds ratio 14.56; 95 % confidence interval: 2.86-74.16, p < 0.001). All patients with ≥10 microbleeds had microbleeds in the lobar region and ≥10 lobar microbleeds was associated with intracerebral hemorrhages, univariable OR 8.54 (2.01-36.33), p = 0.004.

CONCLUSIONS

Leveraging a nationwide database with brain imaging obtained prior to ICrH, we identified a strong association between ≥10 microbleeds on brain MRI and subsequent ICrH among AF patients. Lobar brain regions were involved whenever there were ≥10 microbleeds. Brain MRIs may help optimize the anticoagulation decision in selected AF patients.

Association of Long-Term Blood Pressure Variability with Cerebral Amyloid Angiopathy-related Brain Injury and Cognitive Decline

Introduction

Long-term systolic blood pressure variability (BPV) has been proposed as a novel risk factor for dementia, but the underlying mechanisms are largely unknown. We aimed to investigate the association between long-term blood pressure variability (BPV), brain injury, and cognitive decline in patients with mild cognitive symptoms and cerebral amyloid angiopathy (CAA), a well-characterized small-vessel disease that causes cognitive decline in older adults.

Methods

Using a prospective memory clinic cohort, we enrolled 102 participants, of whom 52 with probable CAA. All underwent a 3-tesla research MRI at baseline and annual neuropsychological evaluation over 2 years, for which standardized z-scores for four cognitive domains were calculated. BPV was assessed using a coefficient of variation derived from serial outpatient BP measurements (median 12) over five years. We measured the peak width of skeletonized mean diffusivity (PSMD) as a marker of white matter integrity, and other neuroimaging markers of CAA, including lacunes and cortical cerebral microinfarcts. Using regression models, we evaluated the association of BPV with microstructural brain injury and whether CAA modified this association. We also examined the association of BPV with subsequent cognitive decline.

Results

Systolic BPV was dose-dependently associated with PSMD (estimate=0.22, 95% CI: 0.06, 0.39, p=0.010), independent of age, sex, mean BP, common vascular risk factors, brain atrophy, and CAA severity. The presence of probable CAA strengthened the association between BPV and PSMD (estimate=9.33, 95% CI: 1.32, 17.34, p for interaction = 0.023). Higher BPV correlated with greater ischemic injury (lobar lacunes and cortical cerebral microinfarcts) and a decline in global cognition and processing speed (estimate=-0.30, 95% CI: -0.55, -0.04, p=0.022).

Discussion

Long-term BPV has a dose-dependent association with alterations in white matter integrity, lobar lacunes, and cortical cerebral microinfarcts, and predicts cognitive decline. Controlling BPV is a potential strategic approach to prevent cognitive decline, especially in early-stage CAA.

Genetic analyses identify brain imaging-derived phenotypes associated with the risk of intracerebral hemorrhage

Previous observational studies have reported associations between brain imaging-derived phenotypes (IDPs) and intracerebral hemorrhage (ICH), but the causality between them remains uncertain. We aimed to investigate the potential causal relationship between IDPs and ICH by a two-sample Mendelian randomization (MR) study. We selected genetic instruments for 363 IDPs from a genome-wide association study (GWASs) based on the UK Biobank (n = 33,224). Summary-level data on ICH was derived from a European-descent GWAS with 1,545 cases and 1,481 controls. Inverse variance weighted MR method was applied in the main analysis to investigate the associations between IDPs and ICH. Reverse MR analyses were performed for significant IDPs to examine the reverse causation for the identified associations. Among the 363 IDPs, isotropic or free water volume fraction (ISOVF) in the anterior limb of the left internal capsule was identified to be associated with the risk of ICH (OR per 1-SD increase, 4.62 [95% CI, 2.18-9.81], P = 6.63 × 10-5). In addition, the reverse MR analysis indicated that ICH had no effect on ISOVF in the anterior limb of the left internal capsule (beta, 0.010 [95% CI, -0.010-0.030], P = 0.33). MR-Egger regression analysis showed no directional pleiotropy for the association between ISOVF and ICH, and sensitivity analyses with different MR models further confirmed these findings. ISOVF in the anterior limb of the left internal capsule might be a potential causal mediator of ICH, which may provide predictive guidance for the prevention of ICH. Further studies are warranted to replicate our findings and clarify the underlying mechanisms.

Domain-specific neuropsychological investigation of CAA with and without intracerebral haemorrhage

BACKGROUND

Cerebral amyloid angiopathy (CAA) is associated with cognitive impairment, but the contributions of lobar intracerebral haemorrhage (ICH), underlying diffuse vasculopathy, and neurodegeneration, remain uncertain. We investigated the domain-specific neuropsychological profile of CAA with and without ICH, and their associations with structural neuroimaging features.

METHODS

Data were collected from patients with possible or probable CAA attending a specialist outpatient clinic. Patients completed standardised neuropsychological assessment covering seven domains. MRI scans were scored for markers of cerebral small vessel disease and neurodegeneration. Patients were grouped into those with and without a macro-haemorrhage (CAA-ICH and CAA-non-ICH).

RESULTS

We included 77 participants (mean age 72, 65% male). 26/32 (81%) CAA-non-ICH patients and 41/45 (91%) CAA-ICH patients were impaired in at least one cognitive domain. Verbal IQ and non-verbal IQ were the most frequently impaired, followed by executive functions and processing speed. We found no significant differences in the frequency of impairment across domains between the two groups. Medial temporal atrophy was the imaging feature most consistently associated with cognitive impairment (both overall and in individual domains) in both univariable and multivariable analyses.

DISCUSSION

Cognitive impairment is common in CAA, even in the absence of ICH, suggesting a key role for diffuse processes related to small vessel disease and/or neurodegeneration. Our findings indicate that neurodegeneration, possibly due to co-existing Alzheimer's disease pathology, may be the most important contributor. The observation that general intelligence is the most frequently affected domain suggests that CAA has a generalised rather than focal cognitive impact.

Anti-Amyloid Therapy, AD, and ARIA: Untangling the Role of CAA

Anti-amyloid therapies (AATs), such as anti-amyloid monoclonal antibodies, are emerging treatments for people with early Alzheimer's disease (AD). AATs target amyloid β plaques in the brain. Amyloid-related imaging abnormalities (ARIA), abnormal signals seen on magnetic resonance imaging (MRI) of the brain in patients with AD, may occur spontaneously but occur more frequently as side effects of AATs. Cerebral amyloid angiopathy (CAA) is a major risk factor for ARIA. Amyloid β plays a key role in the pathogenesis of AD and of CAA. Amyloid β accumulation in the brain parenchyma as plaques is a pathological hallmark of AD, whereas amyloid β accumulation in cerebral vessels leads to CAA. A better understanding of the pathophysiology of ARIA is necessary for early detection of those at highest risk. This could lead to improved risk stratification and the ultimate reduction of symptomatic ARIA. Histopathological confirmation of CAA by brain biopsy or autopsy is the gold standard but is not clinically feasible. MRI is an available in vivo tool for detecting CAA. Cerebrospinal fluid amyloid β level testing and amyloid PET imaging are available but do not offer specificity for CAA vs amyloid plaques in AD. Thus, developing and testing biomarkers as reliable and sensitive screening tools for the presence and severity of CAA is a priority to minimize ARIA complications.

Pathophysiology and probable etiology of cerebral small vessel disease in vascular dementia and Alzheimer's disease

Vascular cognitive impairment and dementia (VCID) is commonly caused by vascular injuries in cerebral large and small vessels and is a key driver of age-related cognitive decline. Severe VCID includes post-stroke dementia, subcortical ischemic vascular dementia, multi-infarct dementia, and mixed dementia. While VCID is acknowledged as the second most common form of dementia after Alzheimer's disease (AD) accounting for 20% of dementia cases, VCID and AD frequently coexist. In VCID, cerebral small vessel disease (cSVD) often affects arterioles, capillaries, and venules, where arteriolosclerosis and cerebral amyloid angiopathy (CAA) are major pathologies. White matter hyperintensities, recent small subcortical infarcts, lacunes of presumed vascular origin, enlarged perivascular space, microbleeds, and brain atrophy are neuroimaging hallmarks of cSVD. The current primary approach to cSVD treatment is to control vascular risk factors such as hypertension, dyslipidemia, diabetes, and smoking. However, causal therapeutic strategies have not been established partly due to the heterogeneous pathogenesis of cSVD. In this review, we summarize the pathophysiology of cSVD and discuss the probable etiological pathways by focusing on hypoperfusion/hypoxia, blood-brain barriers (BBB) dysregulation, brain fluid drainage disturbances, and vascular inflammation to define potential diagnostic and therapeutic targets for cSVD.

Mediators of cognitive impairment in cerebral amyloid angiopathy

BACKGROUND

Cerebral amyloid angiopathy (CAA) is associated with cognitive decline. CAA has diverse impacts on brain structure and function; however, the brain lesions that mediate the association of CAA with cognition are not understood well.

AIMS

To determine the degree to which CAA neuroimaging biomarkers mediate the association of CAA with cognitive dysfunction.

METHODS

We analyzed cross-sectional data of patients with probable CAA and controls without cognitive impairment from the Functional Assessment of Vascular Reactivity study. Neuropsychological tests were grouped into domains of memory, executive function, and processing speed. Candidate CAA neuroimaging biomarkers were pre-specified based on prior literature, consisting of white matter hyperintensity volume, peak width of skeletonized mean diffusivity (PSMD) on diffusion tensor magnetic resonance imaging (MRI), cerebrovascular reactivity (CVR), cortical thickness, and cortical thickness in a meta-region of interest typically affected by Alzheimer's disease (AD). Cognitive scores and neuroimaging markers were standardized and reported in relation to values in controls. Mediation analysis was used to estimate the total effect of CAA on cognition and the proportion of the total effect that was mediated by neuroimaging biomarkers, controlling for age, sex, and education.

RESULTS

There were 131 participants (67 CAA and 64 controls). Mean age was 72.1 ± 7.7 years, and 54.2% were women. As expected, compared to controls, CAA was associated with lower cognition. In mediation analyses, CAA had direct unmediated effects of 48%, 46%, and 52% on all three cognitive domains. The association of CAA with memory was partially mediated by CVR and PSMD, accounting for 18% and 36% of the total effect of CAA. The association of CAA with executive function was partially mediated by PSMD and mean cortical thickness in the AD meta-region of interest (ROI), accounting for 33% and 31% of the total effect of CAA. The association of CAA with processing speed was partially mediated by CVR and PSMD, accounting for 8% and 34% of the total effect of CAA. Among CAA participants, the presence of cortical superficial siderosis was associated with lower processing speed.

CONCLUSION

Altered white matter diffusivity (i.e. PSMD), CVR, and atrophy, taken together, account for about half the effect of CAA on cognition.

Secondary White Matter Injury Mediated by Neuroinflammation after Intracerebral Hemorrhage and Promising Therapeutic Strategies of Targeting the NLRP3 Inflammasome

Intracerebral hemorrhage (ICH) is a neurological disease with high mortality and disability. Recent studies showed that white matter injury (WMI) plays an important role in motor dysfunction after ICH. WMI includes WMI proximal to the lesion and WMI distal to the lesion, such as corticospinal tract injury located at the cervical enlargement of the spinal cord after ICH. Previous studies have tended to focus only on gray matter (GM) injury after ICH, and fewer studies have paid attention to WMI, which may be one of the reasons for the poor outcome of previous drug treatments. Microglia and astrocyte-mediated neuroinflammation are significant mechanisms responsible for secondary WMI following ICH. The NOD-like receptor family, pyrin domain-containing 3 (NLRP3) inflammasome activation, has been shown to exacerbate neuroinflammation and brain injury after ICH. Moreover, NLRP3 inflammasome is activated in microglia and astrocytes and exerts a vital role in microglia and astrocytes-mediated neuroinflammation. We speculate that NLRP3 inflammasome activation is closely related to the polarization of microglia and astrocytes and that NLRP3 inflammasome activation may exacerbate WMI by polarizing microglia and astrocytes to the pro-inflammatory phenotype after ICH, while NLRP3 inflammasome inhibition may attenuate WMI by polarizing microglia and astrocytes to the anti-inflammatory phenotype following ICH. Therefore, NLRP3 inflammasome may act as leveraged regulatory fulcrums for microglia and astrocytes polarization to modulate WMI and WM repair after ICH. This review summarized the possible mechanisms by which neuroinflammation mediated by NLRP3 inflammasome exacerbates secondary WMI after ICH and discussed the potential therapeutic targets.

Oxymatrine ameliorates white matter injury by modulating gut microbiota after intracerebral hemorrhage in mice

INTRODUCTION

White matter injury (WMI) significantly affects neurobehavioral recovery in intracerebral hemorrhage (ICH) patients. Gut dysbiosis plays an important role in the pathogenesis of neurological disorders. Oxymatrine (OMT) has therapeutic effects on inflammation-mediated diseases. Whether OMT exerts therapeutic effects on WMI after ICH and the role of gut microbiota involved in this process is largely unknown.

METHODS

Neurological deficits, WMI, gut microbial composition, intestinal barrier function, and systemic inflammation were investigated after ICH. Fecal microbiota transplantation (FMT) was performed to elucidate the role of gut microbiota in the pathogenesis of ICH.

RESULTS

OMT promoted long-term neurological function recovery and ameliorated WMI in the peri-hematoma region and distal corticospinal tract (CST) region after ICH. ICH induced significant and persistent gut dysbiosis, which was obviously regulated by OMT. In addition, OMT alleviated intestinal barrier dysfunction and systemic inflammation. Correlation analysis revealed that gut microbiota alteration was significantly correlated with inflammation, intestinal barrier permeability, and neurological deficits after ICH. Moreover, OMT-induced gut microbiota alteration could confer protection against neurological deficits and intestinal barrier disruption.

CONCLUSIONS

Our study demonstrates that OMT ameliorates ICH-induced WMI and neurological deficits by modulating gut microbiota.

Peak width of skeletonized mean diffusivity in cerebral amyloid angiopathy: Spatial signature, cognitive, and neuroimaging associations

Background

Peak width of skeletonized mean diffusivity (PSMD) is a promising diffusion tensor imaging (DTI) marker that shows consistent and strong cognitive associations in the context of different cerebral small vessel diseases (cSVD).

Purpose

Investigate whether PSMD (1) is higher in patients with Cerebral Amyloid Angiopathy (CAA) than those with arteriolosclerosis; (2) can capture the anteroposterior distribution of CAA-related abnormalities; (3) shows similar neuroimaging and cognitive associations in comparison to other classical DTI markers, such as average mean diffusivity (MD) and fractional anisotropy (FA).

Materials and methods

We analyzed cross-sectional neuroimaging and neuropsychological data from 90 non-demented memory-clinic subjects from a single center. Based on MRI findings, we classified them into probable-CAA (those that fulfilled the modified Boston criteria), subjects with MRI markers of cSVD not attributable to CAA (presumed arteriolosclerosis; cSVD), and subjects without evidence of cSVD on MRI (non-cSVD). We compared total and lobe-specific (frontal and occipital) DTI metrics values across the groups. We used linear regression models to investigate how PSMD, MD, and FA correlate with conventional neuroimaging markers of cSVD and cognitive scores in CAA.

Results

PSMD was comparable in probable-CAA (median 4.06 × 10^–4 mm²/s) and cSVD (4.07 × 10^–4 mm²/s) patients, but higher than in non-cSVD (3.30 × 10^–4 mm²/s; p < 0.001) subjects. Occipital-frontal PSMD gradients were higher in probable-CAA patients, and we observed a significant interaction between diagnosis and region on PSMD values [F(2, 87) = 3.887, p = 0.024]. PSMD was mainly associated with white matter hyperintensity volume, whereas MD and FA were also associated with other markers, especially with the burden of perivascular spaces. PSMD correlated with worse executive function (β = −0.581, p < 0.001) and processing speed (β = −0.463, p = 0.003), explaining more variance than other MRI markers. MD and FA were not associated with performance in any cognitive domain.

Conclusion

PSMD is a promising biomarker of cognitive impairment in CAA that outperforms other conventional and DTI-based neuroimaging markers. Although global PSMD is similarly increased in different forms of cSVD, PSMD’s spatial variations could potentially provide insights into the predominant type of underlying microvascular pathology.

Effect of vascular amyloid on white matter disease is mediated by vascular dysfunction in cerebral amyloid angiopathy

We postulated that vascular dysfunction mediates the relationship between amyloid load and white matter hyperintensities (WMH) in cerebral amyloid angiopathy (CAA). Thirty-eight cognitively healthy patients with CAA (mean age 70 ± 7.1) were evaluated. WMH was quantified and expressed as percent of total intracranial volume (pWMH) using structural MRI. Mean global cortical Distribution Volume Ratio representing Pittsburgh Compound B (PiB) uptake (PiB-DVR) was calculated from PET scans. Time-to-peak [TTP] of blood oxygen level-dependent response to visual stimulation was used as an fMRI measure of vascular dysfunction. Higher PiB-DVR correlated with prolonged TTP (r = 0.373, p = 0.021) and higher pWMH (r = 0.337, p = 0.039). Prolonged TTP also correlated with higher pWMH (r = 0.485, p = 0.002). In a multivariate linear regression model, TTP remained independently associated with pWMH (p = 0.006) while PiB-DVR did not (p = 0.225). In a bootstrapping model, TTP had a significant indirect effect (ab = 0.97, 95% CI: 0.137-2.461), supporting that the association between PiB-DVR and pWMH is mediated by TTP response. There was no longer a direct effect independent of the hypothesized pathway. Our study suggests that the effect of vascular amyloid load on white matter disease is mediated by vascular dysfunction in CAA. Amyloid lowering strategies might prevent pathophysiological processes leading to vascular dysfunction, therefore limiting ischemic brain injury.

Antithrombotic dilemmas in stroke medicine: new data, unsolved challenges

Antithrombotic therapy is a key element of secondary prevention in patients who have had an ischaemic stroke or transient ischaemic attack. However, its use in clinical practice is not always straightforward. This review provides an update on certain difficult scenarios in antithrombotic management, with a focus on recent clinical trials and large observational studies. We discuss the approach to patients with an indication for antithrombotic treatment who also have clinical or radiological evidence of previous intracranial bleeding, patients with indications for both anticoagulant and antiplatelet treatment, and patients in whom antithrombotic treatment fails to prevent stroke. We also review the timing of anticoagulation initiation after cardioembolic stroke, and the use of antithrombotics in patients with asymptomatic cerebrovascular disease. Despite a wealth of new evidence, numerous uncertainties remain and we highlight ongoing trials addressing these.

Central nervous system injury meets nanoceria: opportunities and challenges

Central nervous system (CNS) injury, induced by ischemic/hemorrhagic or traumatic damage, is one of the most common causes of death and long-term disability worldwide. Reactive oxygen and nitrogen species (RONS) resulting in oxidative/nitrosative stress play a critical role in the pathological cascade of molecular events after CNS injury. Therefore, by targeting RONS, antioxidant therapies have been intensively explored in previous studies. However, traditional antioxidants have achieved limited success thus far, and the development of new antioxidants to achieve highly effective RONS modulation in CNS injury still remains a great challenge. With the rapid development of nanotechnology, novel nanomaterials provided promising opportunities to address this challenge. Within these, nanoceria has gained much attention due to its regenerative and excellent RONS elimination capability. To promote its practical application, it is important to know what has been done and what has yet to be done. This review aims to present the opportunities and challenges of nanoceria in treating CNS injury. The physicochemical properties of nanoceria and its interaction with RONS are described. The applications of nanoceria for stroke and neurotrauma treatment are summarized. The possible directions for future application of nanoceria in CNS injury treatment are proposed.

Intracerebral Hemorrhage: The Effects of Aging on Brain Injury

Intracerebral hemorrhage (ICH) is a devastating subtype of stroke with high rates of mortality and morbidity. ICH patients often suffer devastating and debilitating neurological impairments, from which the majority of victims are unable to fully recover to functional independence. Unfortunately, there is no established medical therapy for ICH, which is partly attributed to the lack of understanding of the complex pathology of the disorder. Despite advanced age being a major risk factor of ICH, most preclinical studies on ICH employed young animal subjects. Due to this discrepancy, the molecular level changes in the aging brain after ICH are largely unknown, limiting the translation of preclinical studies into potential human treatments. The purpose of this review is to highlight the effects of advanced age on ICH- induced brain injury and recovery and to draw attention to current knowledge gaps, which warrant further investigation.

Cerebral Small Vessel Disease and Prognosis in Intracerebral Hemorrhage: A Systematic Review and Meta-analysis of Cohort Studies

BACKGROUND

To investigate whether cerebral small vessel disease (CSVD) markers and the total CSVD burden are associated with functional outcome, mortality, stroke recurrence, and hematoma expansion in patients with spontaneous intracerebral hemorrhage (ICH).

METHODS

Following a previously registered protocol (PROSPERO protocol: CRD42021287743), we systematically searched PubMed, Web of Science, and EMBASE to identify relevant literature up to November 2021. Cohort studies that examined the association between CSVD markers (white matter hyperintensity [WMH], lacune, enlarged perivascular space [EPVS], cerebral microbleed [CMB], and brain atrophy) or CSVD burden and prognosis in patients with ICH were included. The pooled estimates were calculated using random effects models.

RESULTS

Forty-one studies with 19,752 ICH patients were pooled in the meta-analysis. WMH (OR=1.50, 95% CI=1.32 to 1.70), lacune (OR=1.32, 95% CI=1.18 to 1.49), CMB (OR=2.60, 95% CI=1.13 to 5.97) and brain atrophy (OR=2.22, 95% CI=1.48 to 3.31) were associated with worse functional outcome. CSVD markers concerning increased risk of mortality were WMH (OR=1.57, 95% CI=1.38 to 1.79) and brain atrophy (OR=1.84, 95% CI=1.11 to 3.04), while concerning increased risk of stroke recurrence were WMH (OR=1.62, 95% CI=1.28 to 2.04) and lacune (OR=3.00, 95% CI=1.68 to 5.37). EPVS was not related to prognosis. There was a lack of association between CSVD markers and hematoma expansion. CSVD burden increased the risk of worse functional outcome, mortality, and stroke recurrence by 57%, 150%, and 44%, respectively.

CONCLUSIONS

In patients with spontaneous ICH, WMH, lacune, CMB, brain atrophy, and the total CSVD burden are associated with substantially increased risk of worse functional outcome, mortality, or stroke recurrence.

Cerebral Hemorrhage: Pathophysiology, Treatment, and Future Directions

Intracerebral hemorrhage (ICH) is a devastating form of stroke with high morbidity and mortality. This review article focuses on the epidemiology, cause, mechanisms of injury, current treatment strategies, and future research directions of ICH. Incidence of hemorrhagic stroke has increased worldwide over the past 40 years, with shifts in the cause over time as hypertension management has improved and anticoagulant use has increased. Preclinical and clinical trials have elucidated the underlying ICH cause and mechanisms of injury from ICH including the complex interaction between edema, inflammation, iron-induced injury, and oxidative stress. Several trials have investigated optimal medical and surgical management of ICH without clear improvement in survival and functional outcomes. Ongoing research into novel approaches for ICH management provide hope for reducing the devastating effect of this disease in the future. Areas of promise in ICH therapy include prognostic biomarkers and primary prevention based on disease pathobiology, ultra-early hemostatic therapy, minimally invasive surgery, and perihematomal protection against inflammatory brain injury.

Targeting the multifaceted roles of mitochondria in intracerebral hemorrhage and therapeutic prospects

Intracerebral hemorrhage (ICH) is a severe, life-threatening subtype of stoke that constitutes a crucial health and socioeconomic problem worldwide. However, the current clinical treatment can only reduce the mortality of patients to a certain extent, but cannot ameliorate neurological dysfunction and has a high recurrence rate. Increasing evidence has demonstrated that mitochondrial dysfunction occurs in the early stages of brain injury and participates in all stages of secondary brain injury (SBI) after ICH. As the energy source of cells, various pathobiological processes that lead to SBI closely interact with the mitochondria, such as oxidative stress, calcium overload, and neuronal injury. In this review, we discussed the structure and function of mitochondria and the abnormal morphological changes after ICH. In addition, we discussed recent research on the involvement of mitochondrial dynamics in the pathological process of SBI after ICH and introduced the pathological variations and related molecular mechanisms of mitochondrial dysfunction in the occurrence of brain injury. Finally, we summarized the latest progress in mitochondrion-targeted agents for ICH, which provides a direction for the development of emerging therapeutic strategies targeting the mitochondria after ICH.

Vascular Cognitive Impairment (VCI)

Vascular cognitive impairment (VCI) is predominately caused by vascular risk factors and cerebrovascular disease. VCI includes a broad spectrum of cognitive disorders, from mild cognitive impairment to vascular dementia caused by ischemic or hemorrhagic stroke, and vascular factors alone or in a combination with neurodegeneration including Alzheimer's disease (AD) and AD-related dementia. VCI accounts for at least 20-40% of all dementia diagnosis. Growing evidence indicates that cerebrovascular pathology is the most important contributor to dementia, with additive or synergistic interactions with neurodegenerative pathology. The most common underlying mechanism of VCI is chronic age-related dysregulation of CBF, although other factors such as inflammation and cardiovascular dysfunction play a role. Vascular risk factors are prevalent in VCI and if measured in midlife they predict cognitive impairment and dementia in later life. Particularly, hypertension, high cholesterol, diabetes, and smoking at midlife are each associated with a 20 to 40% increased risk of dementia. Control of these risk factors including multimodality strategies with an inclusion of lifestyle modification is the most promising strategy for treatment and prevention of VCI. In this review, we present recent developments in age-related VCI, its mechanisms, diagnostic criteria, neuroimaging correlates, vascular risk determinants, and current intervention strategies for prevention and treatment of VCI. We have also summarized the most recent and relevant literature in the field of VCI.

Cerebral Amyloid Angiopathy and Blood-Brain Barrier Dysfunction

Cerebral hemorrhage, a devastating subtype of stroke, is often caused by hypertension and cerebral amyloid angiopathy (CAA). Pathological evidence of CAA is detected in approximately half of all individuals over the age of 70 and is associated with cortical microinfarcts and cognitive impairment. The underlying pathophysiology of CAA is characterized by accumulation of pathogenic amyloid β (Aβ) fragments of amyloid precursor protein in the cerebral vasculature. Vascular deposition of Aβ damages the vessel wall, results in blood-brain barrier (BBB) leakiness, vessel occlusion or rupture, and leads to hemorrhages and decreased cerebral blood flow that negatively affects vessel integrity and cognitive function. Currently, the main hypothesis surrounding the mechanism of CAA pathogenesis is that there is an impaired clearance of Aβ peptides, which includes compromised perivascular drainage as well as dysfunction of BBB transport. Also, the immune response in CAA pathogenesis plays an important role. Therefore, the mechanism by which Aβ vascular deposition occurs is crucial for our understanding of CAA pathogenesis and for the development of potential therapeutic options.

[Current findings on the coincidence of cerebral amyloid angiopathy and Alzheimer's disease]

Die zerebrale Amyloidangiopathie (CAA) tritt trotz verschiedener Pathomechanismen häufig koinzident zur Alzheimer-Demenz auf. Sie moduliert kognitive Defizite im Rahmen der Alzheimer-Erkrankung (AD) annehmbar durch additive Effekte, auch wenn die diesbezüglichen Zusammenhänge komplex sind. Die pathophysiologische Gemeinsamkeit beider Erkrankungen besteht in einem gestörten Amyloidmetabolismus, distinkt ist jedoch die pathologische Prozessierung von Amyloidvorläuferproteinen. Die CAA mit ihren verschiedenen Subtypen ist eine pathomechanistisch heterogene Gefäßerkrankung des Gehirns. Vaskuläre und parenchymatöse Amyloidablagerungen kommen gemeinsam, aber auch isoliert und unabhängig voneinander vor. Um den spezifischen Beitrag der CAA zu kognitiven Defiziten im Rahmen der AD zu untersuchen, bedarf es daher geeigneter diagnostischer Methoden, die der Komplexität der histopathologischen bzw. bildmorphologischen Charakteristika der CAA gerecht werden, sowie differenzierender testpsychometrischer Verfahren, anhand derer der Beitrag der CAA zu kognitiven Defiziten deskriptiv erfasst und damit ätiologisch besser zuordenbar wird.

MFG-E8 (LACTADHERIN): a novel marker associated with cerebral amyloid angiopathy

Brain accumulation of amyloid-beta (Aβ) is a crucial feature in Alzheimer´s disease (AD) and cerebral amyloid angiopathy (CAA), although the pathophysiological relationship between these diseases remains unclear. Numerous proteins are associated with Aβ deposited in parenchymal plaques and/or cerebral vessels. We hypothesized that the study of these proteins would increase our understanding of the overlap and biological differences between these two pathologies and may yield new diagnostic tools and specific therapeutic targets. We used a laser capture microdissection approach combined with mass spectrometry in the APP23 transgenic mouse model of cerebral-β-amyloidosis to specifically identify vascular Aβ-associated proteins. We focused on one of the main proteins detected in the Aβ-affected cerebrovasculature: MFG-E8 (milk fat globule-EGF factor 8), also known as lactadherin. We first validated the presence of MFG-E8 in mouse and human brains. Immunofluorescence and immunoblotting studies revealed that MFG-E8 brain levels were higher in APP23 mice than in WT mice. Furthermore, MFG-E8 was strongly detected in Aβ-positive vessels in human postmortem CAA brains, whereas MFG-E8 was not present in parenchymal Aβ deposits. Levels of MFG-E8 were additionally analysed in serum and cerebrospinal fluid (CSF) from patients diagnosed with CAA, patients with AD and control subjects. Whereas no differences were found in MFG-E8 serum levels between groups, MFG-E8 concentration was significantly lower in the CSF of CAA patients compared to controls and AD patients. Finally, in human vascular smooth muscle cells MFG-E8 was protective against the toxic effects of the treatment with the Aβ40 peptide containing the Dutch mutation. In summary, our study shows that MFG-E8 is highly associated with CAA pathology and highlights MFG-E8 as a new CSF biomarker that could potentially be used to differentiate cerebrovascular Aβ pathology from parenchymal Aβ deposition.

White Matter Injury After Intracerebral Hemorrhage

Spontaneous intracerebral hemorrhage (ICH) accounts for 15% of all stroke cases. ICH is a devastating form of stroke associated with high morbidity, mortality, and disability. Preclinical studies have explored the mechanisms of neuronal death and gray matter damage after ICH. However, few studies have examined the development of white matter injury (WMI) following ICH. Research on WMI indicates that its pathophysiological presentation involves axonal damage, demyelination, and mature oligodendrocyte loss. However, the detailed relationship and mechanism between WMI and ICH remain unclear. Studies of other acute brain insults have indicated that WMI is strongly correlated with cognitive deficits, neurological deficits, and depression. The degree of WMI determines the short- and long-term prognosis of patients with ICH. This review demonstrates the structure and functions of the white matter in the healthy brain and discusses the pathophysiological mechanism of WMI following ICH. Our review reveals that the development of WMI after ICH is complex; therefore, comprehensive treatment is essential. Understanding the relationship between WMI and other brain cells may reveal therapeutic targets for the treatment of ICH.

A practical approach to the management of cerebral amyloid angiopathy

Cerebral amyloid angiopathy is a common small vessel disease in the elderly involving vascular amyloid-β deposition. Cerebral amyloid angiopathy is one of the leading causes of intracerebral hemorrhage and a significant contributor to age-related cognitive decline. The awareness of a diagnosis of cerebral amyloid angiopathy is important in clinical practice as it impacts decisions to use lifelong anticoagulation or nonpharmacological alternatives to anticoagulation such as left atrial appendage closure in patients who have concurrent atrial fibrillation, another common condition in older adults. This review summarizes the latest literature regarding the management of patients with sporadic cerebral amyloid angiopathy, including diagnostic criteria, imaging biomarkers for cerebral amyloid angiopathy severity, and management strategies to decrease intracerebral hemorrhage risk. In a minority of patients, the presence of cerebral amyloid angiopathy triggers an autoimmune inflammatory reaction, referred to as cerebral amyloid angiopathy-related inflammation, which is often responsive to immunosuppressive treatment in the acute phase. Diagnosis and management of cerebral amyloid angiopathy-related inflammation will be presented separately. While there are currently no effective therapeutics available to cure or halt the progression of cerebral amyloid angiopathy, we discuss emerging avenues for potential future interventions.

Diffuse white matter loss in a transgenic rat model of cerebral amyloid angiopathy

Diffuse white matter (WM) disease is highly prevalent in elderly with cerebral small vessel disease (cSVD). In humans, cSVD such as cerebral amyloid angiopathy (CAA) often coexists with Alzheimer's disease imposing a significant impediment for characterizing their distinct effects on WM. Here we studied the burden of age-related CAA pathology on WM disease in a novel transgenic rat model of CAA type 1 (rTg-DI). A cohort of rTg-DI and wild-type rats was scanned longitudinally using MRI for characterization of morphometry, cerebral microbleeds (CMB) and WM integrity. In rTg-DI rats, a distinct pattern of WM loss was observed at 9 M and 11 M. MRI also revealed manifestation of small CMB in thalamus at 6 M, which preceded WM loss and progressively enlarged until the moribund disease stage. Histology revealed myelin loss in the corpus callosum and thalamic CMB in all rTg-DI rats, the latter of which manifested in close proximity to occluded and calcified microvessels. The quantitation of CAA load in rTg-DI rats revealed that the most extensive microvascular Aβ deposition occurred in the thalamus. For the first time using in vivo MRI, we show that CAA type 1 pathology alone is associated with a distinct pattern of WM loss.

Mechanism of White Matter Injury and Promising Therapeutic Strategies of MSCs After Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is the most fatal subtype of stroke with high disability and high mortality rates, and there is no effective treatment. The predilection site of ICH is in the area of the basal ganglia and internal capsule (IC), where exist abundant white matter (WM) fiber tracts, such as the corticospinal tract (CST) in the IC. Proximal or distal white matter injury (WMI) caused by intracerebral parenchymal hemorrhage is closely associated with poor prognosis after ICH, especially motor and sensory dysfunction. The pathophysiological mechanisms involved in WMI are quite complex and still far from clear. In recent years, the neuroprotection and repairment capacity of mesenchymal stem cells (MSCs) has been widely investigated after ICH. MSCs exert many unique biological effects, including self-recovery by producing growth factors and cytokines, regenerative repair, immunomodulation, and neuroprotection against oxidative stress, providing a promising cellular therapeutic approach for the treatment of WMI. Taken together, our goal is to discuss the characteristics of WMI following ICH, including the mechanism and potential promising therapeutic targets of MSCs, aiming at providing new clues for future therapeutic strategies.

Current Management and Therapeutic Strategies for Cerebral Amyloid Angiopathy

Cerebral amyloid angiopathy (CAA) is characterized by accumulation of amyloid β (Aβ) in walls of leptomeningeal vessels and cortical capillaries in the brain. The loss of integrity of these vessels caused by cerebrovascular Aβ deposits results in fragile vessels and lobar intracerebral hemorrhages. CAA also manifests with progressive cognitive impairment or transient focal neurological symptoms. Although development of therapeutics for CAA is urgently needed, the pathogenesis of CAA remains to be fully elucidated. In this review, we summarize the epidemiology, pathology, clinical and radiological features, and perspectives for future research directions in CAA therapeutics. Recent advances in mass spectrometric methodology combined with vascular isolation techniques have aided understanding of the cerebrovascular proteome. In this paper, we describe several potential key CAA-associated molecules that have been identified by proteomic analyses (apolipoprotein E, clusterin, SRPX1 (sushi repeat-containing protein X-linked 1), TIMP3 (tissue inhibitor of metalloproteinases 3), and HTRA1 (HtrA serine peptidase 1)), and their pivotal roles in Aβ cytotoxicity, Aβ fibril formation, and vessel wall remodeling. Understanding the interactions between cerebrovascular Aβ deposits and molecules that accumulate with Aβ may lead to discovery of effective CAA therapeutics and to the identification of biomarkers for early diagnosis.

Cerebral amyloid angiopathy and related inflammatory disorders

Inflammatory cerebral amyloid angiopathy is a largely reversible inflammatory vasculopathy that develops in an acute or subacute fashion in reaction to amyloid protein deposition in the central nervous system blood vessels. There are two recognized pathologically characterized variants: cerebral amyloid angiopathy-related inflammation (CAAri) and A beta-related angiitis (ABRA). Both variants produce a clinical picture that resembles primary angiitis of the CNS but is distinguished by a characteristic radiologic appearance. Although originally defined as a clinicopathologic diagnosis, it can now often be diagnosed based on clinicoradiologic criteria, though confirmation with brain and meningeal biopsy is still required in some cases. This disorder typically responds to steroids but addition of other immune suppressants may be needed in some cases to control the disease.

Peak Width of Skeletonized Mean Diffusivity as Neuroimaging Biomarker in Cerebral Amyloid Angiopathy

BACKGROUND AND PURPOSE

Whole-brain network connectivity has been shown to be a useful biomarker of cerebral amyloid angiopathy and related cognitive impairment. We evaluated an automated DTI-based method, peak width of skeletonized mean diffusivity, in cerebral amyloid angiopathy, together with its association with conventional MRI markers and cognitive functions.

MATERIALS AND METHODS

We included 24 subjects (mean age, 74.7 [SD, 6.0] years) with probable cerebral amyloid angiopathy and mild cognitive impairment and 62 patients with MCI not attributable to cerebral amyloid angiopathy (non-cerebral amyloid angiopathy-mild cognitive impairment). We compared peak width of skeletonized mean diffusivity between subjects with cerebral amyloid angiopathy-mild cognitive impairment and non-cerebral amyloid angiopathy-mild cognitive impairment and explored its associations with cognitive functions and conventional markers of cerebral small-vessel disease, using linear regression models.

RESULTS

Subjects with Cerebral amyloid angiopathy-mild cognitive impairment showed increased peak width of skeletonized mean diffusivity in comparison to those with non-cerebral amyloid angiopathy-mild cognitive impairment (P < .001). Peak width of skeletonized mean diffusivity values were correlated with the volume of white matter hyperintensities in both groups. Higher peak width of skeletonized mean diffusivity was associated with worse performance in processing speed among patients with cerebral amyloid angiopathy, after adjusting for other MRI markers of cerebral small vessel disease. The peak width of skeletonized mean diffusivity did not correlate with cognitive functions among those with non-cerebral amyloid angiopathy-mild cognitive impairment.

CONCLUSIONS

Peak width of skeletonized mean diffusivity is altered in cerebral amyloid angiopathy and is associated with performance in processing speed. This DTI-based method may reflect the degree of white matter structural disruption in cerebral amyloid angiopathy and could be a useful biomarker for cognition in this population.

Ceria nanoparticles ameliorate white matter injury after intracerebral hemorrhage: microglia-astrocyte involvement in remyelination

Background

Intracerebral hemorrhage (ICH) can induce excessive accumulation of reactive oxygen species (ROS) that may subsequently cause severe white matter injury. The process of oligodendrocyte progenitor cell (OPC) differentiation is orchestrated by microglia and astrocytes, and ROS also drives the activation of microglia and astrocytes. In light of the potent ROS scavenging capacity of ceria nanoparticles (CeNP), we aimed to investigate whether treatment with CeNP ameliorates white matter injury by modulating ROS-induced microglial polarization and astrocyte alteration.

Methods

ICH was induced in vivo by collagenase VII injection. Mice were administered with PLX3397 for depleting microglia. Primary microglia and astrocytes were used for in vitro experiments. Transmission electron microscopy analysis and immunostaining were performed to verify the positive effects of CeNP in remyelination and OPC differentiation. Flow cytometry, real-time polymerase chain reaction, immunofluorescence and western blotting were used to detect microglia polarization, astrocyte alteration, and the underlying molecular mechanisms.

Results

CeNP treatment strongly inhibited ROS-induced NF-κB p65 translocation in both microglia and astrocytes, and significantly decreased the expression of M1 microglia and A1 astrocyte. Furthermore, we found that CeNP treatment promoted remyelination and OPC differentiation after ICH, and such effects were alleviated after microglial depletion. Interestingly, we also found that the number of mature oligodendrocytes was moderately increased in ICH + CeNP + PLX3397-treated mice compared to the ICH + vehicle + PLX3397 group. Therefore, astrocytes might participate in the pathophysiological process. The subsequent phagocytosis assay indicated that A1 astrocyte highly expressed C3, which could bind with microglia C3aR and hinder microglial engulfment of myelin debris. This result further replenished the feedback mechanism from astrocytes to microglia.

Conclusion

The present study reveals a new mechanism in white matter injury after ICH: ICH induces M1 microglia and A1 astrocyte through ROS-induced NF-κB p65 translocation that hinders OPC maturation. Subsequently, A1 astrocytes inhibit microglial phagocytosis of myelin debris via an astrocytic C3-microglial C3aR axis. Polyethylene glycol-CeNP treatment inhibits this pathological process and ultimately promotes remyelination. Such findings enlighten us that astrocytes and microglia should be regarded as a functional unit in future works.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12974-021-02101-6.

Scopoletin Attenuates Intracerebral Hemorrhage-Induced Brain Injury and Improves Neurological Performance in Rats

BACKGROUND

Among the hypertension-related complications, the onset of intracerebral hemorrhage (ICH) is a destructive stage and is the most disabling type of stroke that has the highest death rate. At present, there is no promising treatment for ICH.

OBJECTIVES

The present investigation was aimed at evaluating the safeguarding effect of scopoletin against ICH-induced brain injury.

METHODS

We used Wistar male rats and divided them into 4 groups. Group 1 served as control, group 2 was induced with ICH, group 3 served as scopoletin-pretreated ICH rats, and group 4 as scopoletin drug control. During the experimental period, neurobehavioral outcome, cerebral edema, and neuroinflammation parameters were evaluated using RT-PCR and other biochemical analyses.

RESULTS

The rats that received scopoletin treatment demonstrated a significant attenuation in neurological deficits, neurodegeneration markers expression (TREM-1, SERPINE-1), and restored cerebral edema compared to ICH animals. On the other hand, an upsurge in inflammatory cytokines, for example, TNF-α, IL-13, IL-1β, and IL-17, was observed in ICH rats and was reduced to the level near normalcy in the scopoletin-treated groups.

CONCLUSION

Our investigations propose that the effectiveness of scopoletin in improving acute neurological function after ICH is promising, and this could be a lead molecule for the development of treatment plans in ICH treatment.

The role of biomarkers and neuroimaging in ischemic/hemorrhagic risk assessment for cardiovascular/cerebrovascular disease prevention

Stroke prevention in patients with atrial fibrillation is arguably one of the fastest developing areas in preventive medicine. The increasing use of direct oral anticoagulants and nonpharmacologic methods such as left atrial appendage closure for stroke prevention in these patients has increased clinicians' options for optimal care. Platelet antiaggregants are also commonly used in other ischemic cardiovascular and or cerebrovascular conditions. Long term use of oral anticoagulants for atrial fibrillation is associated with elevated risks of major bleeds including especially brain hemorrhages, which are known to have extremely poor outcomes. Neuroimaging and other biomarkers have been validated to stratify brain hemorrhage risk among older adults. A thorough understanding of these biomarkers is essential for selection of appropriate anticoagulant or left atrial appendage closure for stroke prevention in patients with atrial fibrillation. This article will address advances in the stratification of ischemic and hemorrhagic stroke risk among patients with atrial fibrillation and other conditions.

Predictors for Late Post-Intracerebral Hemorrhage Dementia in Patients with Probable Cerebral Amyloid Angiopathy

BACKGROUND AND OBJECTIVE

Cerebral amyloid angiopathy (CAA) accounts for the majority of lobar intracerebral hemorrhage (ICH); however, the risk factors for dementia conversion after ICH occurrence in CAA patients are unknown, especially in the long-term period after ICH. Therefore, we aimed to unravel the predictors for late post-ICH dementia (6 months after ICH event) in probable CAA patients.

METHODS

From a large consecutive MRI prospective cohort of spontaneous ICH (2006-2017), we identified probable CAA patients (modified Boston criteria) without dementia 6 months post-ICH. Cognitive outcome during follow-up was determined based on the information from standardized clinical visit notes. We used Cox regression analysis to investigate the association between baseline demographic characteristics, past medical history, MRI biomarkers, and late post-ICH dementia conversion (dementia occurred after 6 months).

RESULTS

Among 97 non-demented lobar ICH patients with probable CAA, 25 patients (25.8%) developed dementia during a median follow-up time of 2.5 years (IQR 1.5-3.8 years). Pre-existing mild cognitive impairment, increased white matter hyperintensities (WMH) burden, the presence of disseminated cortical superficial siderosis (cSS), and higher total small vessel disease score for CAA were all independent predictors for late dementia conversion.

CONCLUSION

In probable CAA patients presenting with lobar ICH, high WMH burden and presence of disseminated cSS are useful neuroimaging biomarkers for dementia risk stratification. These findings have implications for clinical practice and future trial design.

Intra-hematomal White Matter Tracts Act As a Scaffold for Macrophage Infiltration After Intracerebral Hemorrhage

Intracerebral hemorrhage (ICH) is a stroke subtype with high mortality and severe morbidity. Hemorrhages frequently develop within the white matter, but whether white matter fibers within the hematoma survive after ICH has not been well studied. The current study examines whether white matter fibers persist in the hematoma after ICH, fibers that might be impacted by evacuation, and their relationship to macrophage infiltration in a porcine model. Male piglets had 2.5 ml blood with or without CD47 blocking antibody injected into the right frontal lobe. Brains were harvested from 3 days to 2 months after ICH for brain histology. White matter fibers were detected within the hematoma 3 and 7 days after hemorrhage by brain histology and myelin basic protein immunohistochemistry. White matter still remained in the hematoma cavity at 2 months after ICH. Macrophage scavenger receptor-1 positive macrophages/microglia and heme oxygenase-1 positive cells infiltrated into the hematoma along the intra-hematomal white matter fibers at 3 and 7 days after ICH. Treatment with CD47 blocking antibody enhanced the infiltration of these cells. In conclusion, white matter fibers exist within the hematoma after ICH and macrophages/microglia may use such fibers as a scaffold to infiltrate into the hematoma and aid in hematoma clearance.

Cerebral Amyloid Angiopathy: A Clinico-Radiological Study from South India

Introduction

Cerebral amyloid angiopathy (CAA) is a major cause of intracerebral hemorrhage (ICH) and cognitive decline in the elderly. Since it is rarely reported from the developing world, we looked into the clinical profile and neuroimaging associations of CAA.

Materials and Methods

Ours was a retrospective case series of subjects diagnosed with probable/possible CAA between January 2006 and December 2015 as per Boston criteria. Clinical profile and neuroimaging were reviewed for markers of CAA. Details of any recurrent clinical events and functional status were collected from follow-up records.

Results

We had 28 subjects in the series with men outnumbering women, and the mean age was 70.17 ± 8.85 years (55-87 years). At the initial presentation, ICH was most frequent-10/28 (35.7%) patients, followed by transient neurological events (TNE = 25%) and cognitive disturbances (21.4%). Less than half of the patients received a diagnosis of CAA at the initial presentation itself. In total, 68% of our patients had cognitive dysfunction at admission. In our series, 12 had seizures and 9 had a history of TNE. The majority of our patients had vascular risk factors also. Leukoaraiosis showed an association with cognitive dysfunction (P = 0.044). Superficial siderosis and subarachnoid hemorrhage (SAH) showed a positive association with seizures and TNE, respectively. However, ICH showed no association with risk factors or imaging markers of CAA.

Conclusions

CAA patients, with a high prevalence of vascular risk factors mostly presented with ICH. The presence of SAH and superficial siderosis on MRI was associated with presentation as TNE and seizures, respectively.

Prospectively Collected Cardiovascular Biomarkers and White Matter Hyperintensity Volume in Ischemic Stroke Patients

BACKGROUND

Few prospective cohort studies collect detailed information on stroke characteristics among individuals who experience ischemic stroke, including white matter hyperintensity volume, and thus cannot explore how prospectively collected biomarkers prior to the stroke influence white matter hyperintensity volume. We explored the association between a large panel of prospectively collected lipid and inflammatory biomarkers and white matter hyperintensity volume among participants in the Women's Health Study with incident ischemic stroke.

METHODS

Among Women's Health Study participants with first ischemic stroke who had baseline serum biomarkers and available magnetic resonance imaging, we measured white matter hyperintensity volume using a validated semi-automated method. Linear regression was used to explore the associations between biomarkers and log-transformed white matter hyperintensity volume.

RESULTS

After multivariate adjustment, a 1% increment in HbA1c% was associated with an increase in white matter hyperintensity volume (P value = .05). Evidence of a nonlinear association between high density lipoprotein cholesterol levels and ApoA1 levels with white matter hyperintensity volume was noted (P values for nonlinearity = .01 and .001, respectively). No other biomarkers were significantly associated with white matter hyperintensity volume.

CONCLUSIONS

Chronic hyperglycemia as evidenced by HbA1c levels measured years prior to stroke is associated with white matter hyperintensity volume at the time of stroke. Additional research is needed to explain why low levels of high density lipoprotein cholesterol levels and ApoA1 may be associated with similar white matter hyperintensity volume as high levels.

Spleen associated immune-response mediates brain-heart interaction after intracerebral hemorrhage

BACKGROUND AND PURPOSE

Intracerebral hemorrhage (ICH) patients frequently encounter cardiovascular complications which may contribute to increased mortality and poor long term outcome. ICH induces systemic oxidative stress and activates peripheral immune responses which are involved in the pathological cascade leading to cardiac dysfunction and heart failure after ICH. We have previously reported that ICH induces progressive cardiac dysfunction in mice without primary cardiac diseases. In this study, we have investigated the role of immune response in mediating cardiac dysfunction post ICH in mice.

METHODS

Adult male C57BL/6 J mice were randomly assigned to the following groups (n = 8/group): 1) sham control; 2) ICH; 3) splenectomy with ICH (ICH + Spx); 4) splenectomy alone (Spx). Echocardiography was performed at 7 and 28 days after ICH. A battery of neurological and cognitive tests were performed. Flow cytometry, western blot and immunostaining were used to test mechanisms of ICH induced cardiac dysfunction.

RESULTS

Compared to sham control mice, Spx alone does not induce acute (7 day) or chronic (28 day) cardiac dysfunction. ICH induces significant neurological and cognitive deficits, as well as acute and chronic cardiac dysfunction compared to sham control mice. Mice subjected to ICH + Spx exhibit significantly improved neurological and cognitive function compared to ICH mice. Mice with ICH + Spx also exhibit significantly improved acute and chronic cardiac function compared to ICH mice indicated by increased left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS), decreased cardiac fibrosis, decreased cardiomyocyte hypertrophy, decreased cardiac infiltration of immune cells and decreased expression of inflammatory factor and oxidative stress in the heart.

CONCLUSIONS

Our study demonstrates that splenectomy attenuates ICH-induced neurological and cognitive impairment as well as ICH-induced cardiac dysfunction in mice. Inflammatory cell infiltration into heart and immune responses mediated by the spleen may contribute to ICH-induce acute and chronic cardiac dysfunction and pathological cardiac remodeling.

Hypertensive Arteriopathy and Cerebral Amyloid Angiopathy in Patients with Cognitive Decline and Mixed Cerebral Microbleeds

BACKGROUND

Hypertensive arteriopathy (HA) and cerebral amyloid angiopathy (CAA) may contribute to the development of mixed cerebral microbleeds (CMBs). Recently, the total small vessel disease (SVD) scores for HA and CAA were proposed, which are determined by a combination of MRI markers to reflect overall severity of these microangiopathies.

OBJECTIVE

We investigated whether or not total HA-SVD and CAA-SVD scores could be used to predict overlap of HA and CAA in patients with mixed CMBs.

METHODS

Fifty-three subjects with mixed CMBs were retrospectively analyzed. MRI markers (CMBs, lacunes, perivascular space, white matter hyperintensity [WMH] and cortical superficial siderosis [cSS]) were assessed. The HA-SVD score and CAA-SVD score were obtained for each subject. Anterior or posterior WMH was also assessed using the age-related white matter changes scale.

RESULTS

The two scores were positively correlated (ρ= 0.449, p < 0.001). The prevalence of lobar dominant CMB distribution (p < 0.001) and lacunes in the centrum semiovale (p < 0.001) and the severity of WMH in the parieto-occipital lobes (p = 0.004) were significantly higher in the high CAA-SVD score group. cSS was found in four patients with high CAA-SVD score who showed lobar-dominant CMB distribution and severe posterior WMH.

CONCLUSION

Mixed CMBs are mainly due to HA. Assessing both two scores may predict the overlap of HA and CAA in individuals with mixed CMBs. Patients with a high CAA-SVD score may have some degree of advanced CAA, especially when lobar predominant CMBs, severe posterior WMH, lobar lacunes, or cSS are observed.

Cognitive impairment before and after intracerebral haemorrhage: a systematic review

INTRODUCTION

There is increasing interest in understanding cognitive dysfunction before and after Intracerebral haemorrhage (ICH), given the higher prevalence of dementia reported (ranging from 5 to 44%) for this stroke type. Much of the evidence to date examining cognitive impairment associated with cerebrovascular disease has tended to focus more on ischaemic stroke. The aim of this review was to identify and quantify studies that focused on cognitive dysfunction pre and post ICH.

METHODS

We conducted a systematic search using databases PubMed, Science Direct, Scopus and PsycINFO to identify studies that exclusively assessed cognitive function pre and post ICH. Studies were included in the review if used a measure of global cognition and/or a neuropsychological battery to assess cognitive function. Nineteen studies were deemed relevant for inclusion, where n = 8 studies examined cognitive impairment pre ICH and n = 11 post ICH.

RESULTS

Prevalence of cognitive impairment ranged between 9-29% for pre ICH and 14-88% for post ICH. Predictive factors identified for pre and post ICH were previous stroke, ICH volume and location and markers of cerebral amyloid angiopathy (CAA). Most common cognitive domains affected post ICH were information processing speed, executive function, memory, language and visuo-spatial abilities. Most common cognitive assessments tools were the Informant Questionnaire for Cognitive Decline in the Elderly (IQCODE) for pre-existing cognitive impairment and the Mini-Mental State Examination for global cognition post ICH and the Trail Making Test where neuropsychological tests were used.

CONCLUSION

Cognitive impairment and dementia affected almost one-third of patients, whether assessed pre or post ICH.

Clinical Significance of Magnetic Resonance Imaging Markers of Vascular Brain Injury: A Systematic Review and Meta-analysis

Importance

Covert vascular brain injury (VBI) is highly prevalent in community-dwelling older persons, but its clinical and therapeutic implications are debated.

Objective

To better understand the clinical significance of VBI to optimize prevention strategies for the most common age-related neurological diseases, stroke and dementia.

Data Source

We searched for articles in PubMed between 1966 and December 22, 2017, studying the association of 4 magnetic resonance imaging (MRI) markers of covert VBI (white matter hyperintensities [WMHs] of presumed vascular origin, MRI-defined covert brain infarcts [BIs], cerebral microbleeds [CMBs], and perivascular spaces [PVSs]) with incident stroke, dementia, or death.

Study Selection

Data were taken from prospective, longitudinal cohort studies including 50 or more adults.

Data Extraction and Synthesis

We performed inverse variance-weighted meta-analyses with random effects and z score-based meta-analyses for WMH burden. The significance threshold was P < .003 (17 independent tests). We complied with the Meta-analyses of Observational Studies in Epidemiology guidelines.

Main Outcomes and Measures

Stroke (hemorrhagic and ischemic), dementia (all and Alzheimer disease), and death.

Results

Of 2846 articles identified, 94 studies were eligible, with up to 14 529 participants for WMH, 16 012 participants for BI, 15 693 participants for CMB, and 4587 participants for PVS. Extensive WMH burden was associated with higher risk of incident stroke (hazard ratio [HR], 2.45; 95% CI, 1.93-3.12; P < .001), ischemic stroke (HR, 2.39; 95% CI, 1.65-3.47; P < .001), intracerebral hemorrhage (HR, 3.17; 95% CI, 1.54-6.52; P = .002), dementia (HR, 1.84; 95% CI, 1.40-2.43; P < .001), Alzheimer disease (HR, 1.50; 95% CI, 1.22-1.84; P < .001), and death (HR, 2.00; 95% CI, 1.69-2.36; P < .001). Presence of MRI-defined BIs was associated with higher risk of incident stroke (HR, 2.38; 95% CI, 1.87-3.04; P < .001), ischemic stroke (HR, 2.18; 95% CI, 1.67-2.85; P < .001), intracerebral hemorrhage (HR, 3.81; 95% CI, 1.75-8.27; P < .001), and death (HR, 1.64; 95% CI, 1.40-1.91; P < .001). Presence of CMBs was associated with increased risk of stroke (HR, 1.98; 95% CI, 1.55-2.53; P < .001), ischemic stroke (HR, 1.92; 95% CI, 1.40-2.63; P < .001), intracerebral hemorrhage (HR, 3.82; 95% CI, 2.15-6.80; P < .001), and death (HR, 1.53; 95% CI, 1.31-1.80; P < .001). Data on PVS were limited and insufficient to conduct meta-analyses but suggested an association of high PVS burden with increased risk of stroke, dementia, and death; this requires confirmation.

Conclusions and Relevance

We report evidence that MRI markers of VBI have major clinical significance. This research prompts careful evaluation of the benefit-risk ratio for available prevention strategies in individuals with covert VBI.

White matter repair and treatment strategy after intracerebral hemorrhage

The predilection site of intracerebral hemorrhage (ICH) is in the basal ganglia, which is rich in white matter (WM) fiber bundles, such as cerebrospinal tract in the internal capsule. ICH induced damage to this area can easily lead to severe neurological dysfunction and affects the prognosis and quality of life of patients. At present, the pathophysiological mechanisms of white matter injury (WMI) after ICH have attracted researchers' attention, but studies on the repair and recovery mechanisms and therapy strategies remain rare. In this review, we mainly summarized the WM recovery and treatment strategies after ICH by updating the WMI-related content by reviewing the latest researches and proposing the bottleneck of the current research.

[Cerebral amyloid angiopathy revealed or hypertension-related cerebral small vessel diseases: A clinical challenge]

Cerebral amyloid angiopathy (CAA) is a entity characterized by degenerative Amyloïd deposits in the walls of the meningeal and cortical vessels. It is considered as the second cause of primitives cerebral hemorrhage in elderly. The differential diagnosis between AAC and hypertension-related cerebral small vessel diseases is difficult and represent a true challenge for the clinician. We report two cases of cerebral small vessel diseases revealed by malignant hypertension.

Prospectively collected lifestyle and health information as risk factors for white matter hyperintensity volume in stroke patients

Most studies of white matter hyperintensity volume (WMHV) in stroke patients lack reliable information on antecedent exposure to vascular risk factors. By leveraging prospective cohort data, we explored associations between lifestyle and health factors assessed 1 year prior to stroke and WMHV in individuals who experienced an ischemic stroke. This analysis was nested within two large prospective studies of initially healthy individuals. Information on lifestyle factors and health conditions was collected prior to the stroke event through annual or biannual questionnaires. For individuals who experienced their first confirmed ischemic stroke and had available magnetic resonance imaging, we measured WMHV using a validated semiautomated method. Linear regression was used to explore associations between lifestyle factors and health conditions and log-transformed WMHV. We measured WMHV in 345 participants with a first ischemic stroke event (mean age = 74.4 years; 24.9% male). After multivariate adjustment, history of diabetes was associated with decreased WMHV (p value = 0.06) while history of transient ischemic attack (p value = 0.09) and hypertension (p value = 0.07) were associated with increased WMHV. Most lifestyle factors and health conditions measured 1 year prior to stroke were not associated with WMHV measured at the time of ischemic stroke. Future studies could examine whether long term exposure to these factors impacts diffuse microvascular ischemic brain injury among stroke patients.

Advances in cerebral amyloid angiopathy imaging

Cerebral amyloid angiopathy (CAA) is a cerebral small vessel disease caused by β -amyloid (Aβ) deposition at the leptomeningeal vessel walls. It is a common cause of spontaneous intracerebral hemorrhage and a frequent comorbidity in Alzheimer’s disease. The high recurrent hemorrhage rate in CAA makes it very important to recognize this disease to avoid potential harmful medication. Imaging studies play an important role in diagnosis and research of CAA. Conventional computed tomography and magnetic resonance imaging (MRI) methods reveal anatomical alterations, and remains as the most reliable tool in identifying CAA according to modified Boston criteria. The vascular injuries of CAA result in both hemorrhagic and ischemic manifestations and related structural changes on MRI, including cerebral microbleeds, cortical superficial siderosis, white matter hyperintensity, MRI-visible perivascular spaces, and cortical microinfarcts. As imaging techniques advance, not only does the resolution of conventional imaging improve, but novel skills in functional and molecular imaging studies also enable in vivo analysis of vessel physiological changes and underlying pathology. These modern tools help in early detection of CAA and may potentially serve as sensitive outcome markers in future clinical trials. In this article, we reviewed past studies of CAA focusing on utilization of various conventional and novel imaging techniques in both research and clinical aspects.