Neuropathology of White Matter Lesions, Blood-Brain Barrier Dysfunction, and Dementia

The canine blood-brain barrier in health and disease: focus on brain protection

This review examines the role of the canine blood-brain barrier (BBB) in health and disease, focusing on the impact of the multidrug resistance (MDR) transporter P-glycoprotein (P-gp) encoded by the ABCB1/MDR1 gene. The BBB is critical in maintaining central nervous system homeostasis and brain protection against xenobiotics and environmental drugs that may be circulating in the blood stream. We revise key anatomical, histological and functional aspects of the canine BBB and examine the role of the ABCB1/MDR1 gene mutation in specific dog breeds that exhibit reduced P-gp activity and disrupted drug brain pharmacokinetics. The review also covers factors that may disrupt the canine BBB, including the actions of aging, canine cognitive dysfunction, epilepsy, inflammation, infection, traumatic brain injury, among others. We highlight the critical importance of this barrier in maintaining central nervous system homeostasis and protecting against xenobiotics and conclude that a number of neurological-related diseases may increase vulnerability of the BBB in the canine species and discuss its profound impacts on canine health.

Protective effects of berbamine against arginase-1 deficiency-induced injury in human brain microvascular endothelial cells

Endothelial cell dysfunction plays a crucial role in the early development of cerebral small vessel disease (CSVD). Arginase-1 (ARG1) is expressed in endothelial cells, and its deficiency may exacerbate cerebrovascular damage by increasing reactive oxygen species (ROS) production, thereby inducing endothelial cell apoptosis. Berbamine (BBM) has shown potential in neuroprotection and cardiovascular disease prevention. This study aimed to investigate the impact of ARG1 deficiency on human brain microvascular endothelial cells and the protective effects of BBM against ARG1 deficiency-induced damage. Human brain microvascular endothelial cells (HCMEC/D3) were cultured in vitro, and ARG1 knockdown or overexpression was achieved using plasmid transfection techniques. We examined the effects of ARG1 expression levels on HCMEC/D3 cell viability, migration, apoptosis, adhesion, and angiogenesis through cellular experiments. Additionally, we explored how ARG1 expression levels influenced arginine (Arg), nitric oxide (NO), and ROS levels in HCMEC/D3 cells. The results demonstrated that ARG1 deficiency inhibited HCMEC/D3 cell viability, migration, adhesion, and angiogenesis, while promoting apoptosis and elevating Arg, NO, and ROS levels in HCMEC/D3 cells. Next, the effect of different BBM concentrations on HCMEC/D3 cell viability was assessed using the CCK-8 assay, revealing that BBM at a concentration of 5 µM had no significant impact on cell viability. Subsequently, after successfully knocking down ARG1 in HCMEC/D3 cells, the cells were treated with BBM. The results showed that BBM effectively mitigated the negative effects of ARG1 deficiency on HCMEC/D3 cell viability, migration, apoptosis, adhesion, and angiogenesis, while also reducing Arg, NO, inducible nitric oxide synthase (iNOS), and ROS levels in HCMEC/D3 cells. In conclusion, this study suggests that ARG1 deficiency may damage HCMEC/D3 cells by increasing Arg levels, leading to elevated NO and ROS levels. BBM may provide protection to ARG1-deficient HCMEC/D3 cells by reducing Arg, NO, iNOS, and ROS levels. These findings deepen our understanding of the pathogenesis of CSVD and provide a theoretical basis for the clinical application of BBM.

White matter hyperintensity genetic risk factor TRIM47 regulates autophagy in brain endothelial cells

White matter hyperintensity (WMH) is strongly correlated with age-related dementia and hypertension, but its pathogenesis remains obscure. Genome-wide association studies identified TRIM47 at the 17q25 locus as a top genetic risk factor for WMH formation. TRIM family is a class of E3 ubiquitin ligase with pivotal functions in autophagy, which is critical for brain endothelial cell (ECs) remodeling during hypertension. We hypothesize that TRIM47 regulates autophagy and its loss-of-function disturbs cerebrovasculature. Based on transcriptomics and immunohistochemistry, TRIM47 is found highly expressed by brain ECs in human and mouse, and its transcription is upregulated by artificially induced autophagy while downregulated in hypertension-like conditions. Using in silico simulation, immunocytochemistry and super-resolution microscopy, we predicted a highly conserved binding site between TRIM47 and the LIR (LC3-interacting region) motif of LC3B. Importantly, pharmacological autophagy induction increased Trim47 expression on mouse ECs (b.End3) culture, while silencing Trim47 significantly increased autophagy with ULK1 phosphorylation induction, transcription, and vacuole formation. Together, we demonstrate that TRIM47 is an endogenous inhibitor of autophagy in brain ECs, and such TRIM47-mediated regulation connects genetic and physiological risk factors for WMH formation but warrants further investigation.

Cerebrovascular disease is associated with Alzheimer's plasma biomarker concentrations in adults with Down syndrome

By age 40 years, over 90% of adults with Down syndrome have Alzheimer's disease pathology and most progress to dementia. Despite having few systemic vascular risk factors, individuals with Down syndrome have elevated cerebrovascular disease markers that track with the clinical progression of Alzheimer's disease, suggesting a role of cerebrovascular disease that is hypothesized to be mediated by inflammatory factors. This study examined the pathways through which small vessel cerebrovascular disease contributes to Alzheimer's disease-related pathophysiology and neurodegeneration in adults with Down syndrome. One hundred eighty-five participants from the Alzheimer's Biomarkers Consortium-Down Syndrome [mean (SD) age = 45.2 (9.3) years] with available MRI and plasma biomarker data were included in this study. White matter hyperintensity (WMH) volumes were derived from T2-weighted fluid-attenuated inversion recovery MRI scans, and plasma biomarker concentrations of amyloid beta 42/40, phosphorylated tau 217, astrocytosis (glial fibrillary acidic protein) and neurodegeneration (neurofilament light chain) were measured with ultrasensitive immunoassays. We examined the bivariate relationships of WMH, amyloid beta 42/40, phosphorylated tau 217 and glial fibrillary acidic protein with age-residualized neurofilament light chain across Alzheimer's disease diagnostic groups. A series of mediation and path analyses examined statistical pathways linking WMH and Alzheimer's disease pathophysiology to promote neurodegeneration in the total sample and groups stratified by clinical diagnosis. There was a direct and indirect bidirectional effect through the glial fibrillary acidic protein of WMH on phosphorylated tau 217 concentration, which was associated with neurofilament light chain concentration in the entire sample. Amongst cognitively stable participants, WMH was directly and indirectly, through glial fibrillary acidic protein, associated with phosphorylated tau 217 concentration, and in those with mild cognitive impairment, there was a direct effect of WMH on phosphorylated tau 217 and neurofilament light chain concentrations. There were no associations of WMH with biomarker concentrations among those diagnosed with dementia. The findings from this cross-sectional study suggest that among individuals with Down syndrome, cerebrovascular disease promotes neurodegeneration by increasing astrocytosis and tau pathophysiology in the presymptomatic phases of Alzheimer's disease, but future studies will need to confirm these associations with longitudinal data. This work joins an emerging literature that implicates cerebrovascular disease and its interface with neuroinflammation as a core pathological feature of Alzheimer's disease in adults with Down syndrome.

ω-3 PUFA for Secondary Prevention of White Matter Lesions and Neuronal Integrity Breakdown in Older Adults: A Randomized Clinical Trial

Importance

Older adults with lower intake and tissue levels of long-chain ω-3 polyunsaturated fatty acids (PUFAs) eicosapentaenoic acid (EPA; 20:5) and docosahexaenoic acid (DHA; 22:6) have more brain white matter lesions (WMLs), an association suggesting that small-vessel ischemic disease, a major contributor to the development of dementia, including Alzheimer disease, may be preventable through ω-3 treatment.

Objective

To determine whether ω-3 treatment reduces WML accumulation in older adults without dementia harboring WMLs and with suboptimal ω-3 status.

Design, Setting, and Participants

This quadruple-blinded, placebo-controlled, randomized clinical trial with treatment stratification by apolipoprotein E ε4 allele (APOE*E4) carrier status used linear mixed-effects models to estimate mean annual change between groups. The study was conducted at Oregon Health & Science University, a major academic medical center in the Pacific Northwest, from May 2014 to final participant visit in September 2019. Data analysis concluded in July 2022. Participants were adults without dementia aged 75 years and older with WMLs greater than or equal to 5 cm3 and plasma ω-3 PUFA less than 5.5 weight percentage of total.

Intervention

Three-year treatment with 1.65 g of ω-3 PUFA (975 mg of EPA and 650 mg of DHA) vs a soybean oil placebo matched for taste, smell, and appearance.

Main Outcomes and Measures

The primary outcome was annual WML progression measured using magnetic resonance imaging. Secondary outcomes included diffusion tensor imaging of fractional anisotropy (DTI-FA), representing neuronal integrity breakdown.

Results

A total of 102 participants (62 women [60.8%]; mean age, 81 years [range, 75-96 years]) were equally randomized, 51 per treatment group. Although the ω-3 group had less annual WML accumulation than the placebo group, the difference was not statistically significant (1.19 cm3 [95% CI, 0.64-1.74 cm3] vs 1.34 cm3 [95% CI, 0.80-1.88 cm3]; P = .30). Similarly, the ω-3 group had less annual DTI-FA decline than the placebo group, but the difference was not statistically significant (-0.0014 mm2/s [95% CI, -0.0027 to 0.0002 mm2/s] vs -0.0027 mm2/s [95% CI, -0.0041 to -0.0014 mm2/s]; P = .07). Among APOE*E4 carriers, the annual DTI-FA decline was significantly lower in the group treated with ω-3 than the placebo group (-0.0016 mm2/s [95% CI, -0.0032 to 0.0020 mm2/s] vs -0.0047 mm2/s [95% CI, -0.0067 to -0.0025 mm2/s]; P = .04). Adverse events were similar between treatment groups.

Conclusions and Relevance

In this 3-year randomized clinical trial, ω-3 treatment was safe and well-tolerated but failed to reach significant reductions in WML accumulation or neuronal integrity breakdown among all participants, which may be attributable to sample size limitations. However, neuronal integrity breakdown was reduced by ω-3 treatment in APOE*E4 carriers, suggesting that this treatment may be beneficial for this specific group.

Trial Registration

ClinicalTrials.gov Identifier: NCT01953705.

Aldosterone is Associated With New-onset Cerebrovascular Events in Patients With Hypertension and White Matter Lesions: A Cohort Study

OBJECTIVE

White matter lesions (WMLs) increase the risk of stroke, stroke recurrence, and death. Higher plasma aldosterone concentration (PAC) increases the risk of stroke, acute myocardial infarction, and hypertension. The objective is to evaluate the relationship between PAC and cerebrovascular events in patients with hypertension and WMLs.

METHODS

We conducted a retrospective cohort study that included 1041 participants hospitalized. The outcome was new-onset cerebrovascular events including intracerebral hemorrhage and stroke. A Cox regression model was used to evaluate the relationship between baseline PAC and the risk of cerebrovascular events.

RESULTS

The mean age of participants was 60.9 ± 10.2 years and 565 (53.4%) were males. The median follow-up duration was 42 months (interquartile range: 25-67), and 92 patients experienced new-onset cerebrovascular events. In a multivariate-adjusted model, with PAC as a continuous variable, higher PAC increased the risk of cerebrovascular events; patient risk increased per 1 (hazard ratio [HR: 1.03], 95% confidence interval [CI]: 1.01-1.06, P < .01), per 5 (HR: 1.17, 95% CI: 1.06-1.31, P < .01), and per 10 ng/dL (HR: 1.41, 95%: 1.14-1.75, P < .01) increase in PAC. When PAC was expressed as a categorical variable (quartile: Q1-Q4), patients in Q4 (HR: 2.12, 95% CI: 1.18-3.79, P < .05) exhibited an increased risk of cerebrovascular events compared to Q1. Restrictive spline regression showed a linear association between PAC and the risk of new-onset cerebrovascular events after adjusting for all possible variables.

CONCLUSIONS

Our study identified a linear association between PAC and the risk of new-onset cerebrovascular events in patients with hypertension and WMLs.

Blood-Brain Barrier Permeability Is Associated With Cognitive Functioning in Normal Aging and Neurodegenerative Diseases

BACKGROUND

The purpose of this study was to investigate the relationship between blood-brain barrier (BBB) permeability and cognitive functioning in healthy older adults and individuals with neurodegenerative diseases.

METHODS AND RESULTS

A total of 124 participants with Alzheimer disease, cerebrovascular disease, or a mix Alzheimer's and cerebrovascular diseases and 55 controlparticipants underwent magnetic resonance imaging and neuropsychological testing. BBB permeability was measured with dynamic contrast-enhanced magnetic resonance imaging and white matter injury was measured using a quantitative diffusion-tensor imaging marker of white matter injury. Structural equation modeling was used to examine the relationships between BBB permeability, vascular risk burden, white matter injury, and cognitive functioning. Vascular risk burden predicted BBB permeability (r=0.24, P<0.05) and white matter injury (r=0.38, P<0.001). BBB permeability predicted increased white matter injury (r=0.34, P<0.001) and increased white matter injury predicted lower cognitive functioning (r=-0.51, P<0.001).

CONCLUSIONS

The study provides empirical support for a vascular contribution to white matter injury and cognitive impairment, directly or indirectly via BBB permeability. This highlights the importance of targeting modifiable vascular risk factors to help mitigate future cognitive decline.

Relationship Between Coronary Artery Revascularization and Postoperative Delirium: Progress and Perspectives

Brain dysfunction resulting from damage to the heart-brain link leads to a decline in cognitive function. This, in turn, gives rise to the clinical symptom of perioperative delirium in patients undergoing coronary artery revascularization. Those affected are provided symptomatic treatment, but many do not recover fully. Thus, medium- and long-term mortality and adverse event rates remain relatively high in patients with perioperative delirium. Despite the relatively high incidence of perioperative delirium in patients undergoing coronary artery revascularization, it has not been systematically investigated. Inflammation, vascular damage, neuronal damage, and embolism are all involved in the injury process. Here, we discuss the incidence rate, pathological mechanisms, and prognosis of delirium after coronary artery revascularization. We also discuss in detail the risk factors for delirium after coronary artery revascularization, such as anxiety, depression, mode of operation, and drug use. We hope that prevention, early diagnosis, assessment, and potential treatment can be achieved by cardiologists to improve patient prognosis.

White matter hyperintensity genetic risk factor TRIM47 regulates autophagy in brain endothelial cells

White matter hyperintensity (WMH) is strongly correlated with age-related dementia and hypertension, but its pathogenesis remains obscure. GWAS identified TRIM47 at 17q25 locus as a top genetic risk factor for WMH formation. TRIM family is a class of E3 ubiquitin ligase with pivotal functions in autophagy, which is critical for brain endothelial cell (ECs) remodeling during hypertension. We hypothesize that TRIM47 regulates autophagy and its loss-of-function disturbs cerebrovasculature. Based on transcriptomics and immunohistochemistry, TRIM47 is found selectively expressed by brain ECs in human and mouse, and its transcription is upregulated by artificially-induced autophagy while downregulated in hypertension-like conditions. Using in silico simulation, immunocytochemistry and super-resolution microscopy, we identified the highly conserved binding site between TRIM47 and the LIR (LC3-interacting region) motif of LC3B. Importantly, pharmacological autophagy induction increased Trim47 expression on mouse ECs (b.End3) culture, while silencing Trim47 significantly increased autophagy with ULK1 phosphorylation induction, transcription and vacuole formation. Together, we confirm that TRIM47 is an endogenous inhibitor of autophagy in brain ECs, and such TRIM47-mediated regulation connects genetic and physiological risk factors for WMH formation but warrants further investigation.

SUMMARY STATEMENT

TRIM47, top genetic risk factor for white matter hyperintensity formation, is a negative regulator of autophagy in brain endothelial cells and implicates a novel cellular mechanism for age-related cerebrovascular changes.

Cerebral Small Vessel Disease, Hypertension, and Vascular Contributions to Cognitive Impairment and Dementia

Hypertension-associated cerebral small vessel disease is a common finding in older people. Strongly associated with age and hypertension, small vessel disease is found at autopsy in over 50% of people aged ≥65 years, with a spectrum of clinical manifestations. It is the main cause of lacunar stroke and a major source of vascular contributions to cognitive impairment and dementia. The brain areas affected are subcortical and periventricular white matter and deep gray nuclei. Neuropathological sequelae are diffuse white matter lesions (seen as white matter hyperintensities on T2-weighted magnetic resonance imaging), small ischemic foci (lacunes or microinfarcts), and less commonly, subcortical microhemorrhages. The most common form of cerebral small vessel disease is concentric, fibrotic thickening of small penetrating arteries (up to 300 microns outer diameter) termed arteriolosclerosis. Less common forms are small artery atheroma and lipohyalinosis (the lesions described by C. Miller Fisher adjacent to lacunes). Other microvascular lesions that are not reviewed here include cerebral amyloid angiopathy and venous collagenosis. Here, we review the epidemiology, neuropathology, clinical management, genetics, preclinical models, and pathogenesis of hypertensive small vessel disease. Knowledge gaps include initiating factors, molecular pathogenesis, relationships between arterial pathology and tissue damage, possible reversibility, pharmacological targets, and molecular biomarkers. Progress is anticipated from multicell transcriptomic and proteomic profiling, novel experimental models and further target-finding and interventional clinical studies.

Cerebrovascular disease drives Alzheimer plasma biomarker concentrations in adults with Down syndrome

Importance

By age 40 years over 90% of adults with Down syndrome (DS) have Alzheimer's disease (AD) pathology and most progress to dementia. Despite having few systemic vascular risk factors, individuals with DS have elevated cerebrovascular disease (CVD) markers that track with the clinical progression of AD, suggesting a role for CVD that is hypothesized to be mediated by inflammatory factors.

Objective

To examine the pathways through which small vessel CVD contributes to AD-related pathophysiology and neurodegeneration in adults with DS.

Design

Cross sectional analysis of neuroimaging, plasma, and clinical data.

Setting

Participants were enrolled in Alzheimer's Biomarker Consortium - Down Syndrome (ABC-DS), a multisite study of AD in adults with DS.

Participants

One hundred eighty-five participants (mean [SD] age=45.2 [9.3] years) with available MRI and plasma biomarker data were included. White matter hyperintensity (WMH) volumes were derived from T2-weighted FLAIR MRI scans and plasma biomarker concentrations of amyloid beta (Aβ42/Aβ40), phosphorylated tau (p-tau217), astrocytosis (glial fibrillary acidic protein, GFAP), and neurodegeneration (neurofilament light chain, NfL) were measured with ultrasensitive immunoassays.

Main Outcomes and Measures

We examined the bivariate relationships of WMH, Aβ42/Aβ40, p-tau217, and GFAP with age-residualized NfL across AD diagnostic groups. A series of mediation and path analyses examined causal pathways linking WMH and AD pathophysiology to promote neurodegeneration in the total sample and groups stratified by clinical diagnosis.

Results

There was a direct and indirect bidirectional effect through GFAP of WMH on p-tau217 concentration, which was associated with NfL concentration in the entire sample. Among cognitively stable participants, WMH was directly and indirectly, through GFAP, associated with p-tau217 concentration, and in those with MCI, there was a direct effect of WMH on p-tau217 and NfL concentrations. There were no associations of WMH with biomarker concentrations among those diagnosed with dementia.

Conclusions and Relevance

The findings suggest that among individuals with DS, CVD promotes neurodegeneration by increasing astrocytosis and tau pathophysiology in the presymptomatic phases of AD. This work joins an emerging literature that implicates CVD and its interface with neuroinflammation as a core pathological feature of AD in adults with DS.

Diffusion tensor free water MRI predicts progression of FLAIR white matter hyperintensities after ischemic stroke

Background

The progression of FLAIR white matter hyperintensities (WMHs) on MRI heralds vascular-mediated cognitive decline. Even before FLAIR WMH progression, adjacent normal appearing white matter (NAWM) already demonstrates microstructural deterioration on diffusion tensor imaging (DTI). We hypothesized that elevated DTI free water (FW) would precede FLAIR WMH progression, implicating interstitial fluid accumulation as a key pathological step in the progression of cerebral small vessel disease.

Methods

Participants at least 3 months after an ischemic stroke or TIA with WMH on MRI underwent serial brain MRIs every 3 months over the subsequent year. For each participant, the WMHs were automatically segmented, serial MRIs were aligned, and a region of WMH penumbra tissue at risk was defined by dilating lesions at any time point and subtracting baseline lesions. Penumbra voxels were classified as either stable or progressing to WMH if they were segmented as new lesions and demonstrated increasing FLAIR intensity over time. Aligned DTI images included FW and FW-corrected fractional anisotropy (FATissue) and mean diffusivity (MDTissue). Logistic regression and area under the receiver-operator characteristic curve (AUC) were used to test whether baseline DTI predicted voxel-wise classification of stable penumbra or progression to WMH while covarying for clinical risk factors.

Results

In the included participants (n = 26, mean age 71 ± 9 years, 31% female), we detected a median annual voxel-wise WMH growth of 2.9 ± 2.6 ml. Each baseline DTI metric was associated with lesion progression in the penumbra, but FW had the greatest AUC of 0.732 (0.730 - 0.733) for predicting voxel-wise WMH progression pooled across participants.

Discussion

Baseline increased interstitial fluid, estimated as FW on DTI, predicted the progression of NAWM to WMH over the following year. These results implicate the presence of FW in the pathogenesis of cerebral small vessel disease progression.

Blood-brain barrier leakage hotspots collocating with brain lesions due to sporadic and monogenic small vessel disease

Blood-brain barrier (BBB) is known to be impaired in cerebral small vessel disease (SVD), and is measurable by dynamic-contrast enhancement (DCE)-MRI. In a cohort of 69 patients (42 sporadic, 27 monogenic SVD), who underwent 3T MRI, including DCE and cerebrovascular reactivity (CVR) sequences, we assessed the relationship of BBB-leakage hotspots to SVD lesions (lacunes, white matter hyperintensities (WMH), and microbleeds). We defined as hotspots the regions with permeability surface area product highest decile on DCE-derived maps within the white matter. We assessed factors associated with the presence and number of hotspots corresponding to SVD lesions in multivariable regression models adjusted for age, WMH volume, number of lacunes, and SVD type. We identified hotspots at lacune edges in 29/46 (63%) patients with lacunes, within WMH in 26/60 (43%) and at the WMH edges in 34/60 (57%) patients with WMH, and microbleed edges in 4/11 (36%) patients with microbleeds. In adjusted analysis, lower WMH-CVR was associated with presence and number of hotspots at lacune edges, and higher WMH volume with hotspots within WMH and at WMH edges, independently of the SVD type. In conclusion, SVD lesions frequently collocate with high BBB-leakage in patients with sporadic and monogenic forms of SVD.

Predicting cerebral white matter lesions based on the platelet-to-white blood cell ratio in hypertensive patients

Hypertension is a common chronic disease affecting many people. White matter lesions (WMLs) are one of the imaging features of cerebrovascular disease. Predicting the possibility of developing syncretic WMLs in patients with hypertension may contribute to the early identification of serious clinical conditions. This study aims to build a model to identify patients who suffered from moderate-to-severe WMLs by using recognized WMLs risk factors including age and history of diabetes and a new factor named platelet-to-white blood cell ratio (PWR). A total of 237 patients were included in this study. The Affiliated ZhongDa Hospital of Southeast University Research Ethics Committee approved this study (Ethics No. 2019ZDSYLL189-P01). We developed a nomogram to predict the risk of syncretic WMLs in patients with hypertension using the above factors. Higher total scores on the nomogram indicated a higher risk of syncretic WMLs. This means older age, smaller PWR, and patients suffering from diabetes contributed to a greater chance for the patient to suffer from syncretic WMLs. We used a decision analysis curve(DCA) to determine the net benefit of the prediction model. The DCA we constructed showed that using our model to decide whether patients suffered from syncretic WMLs or not was better than assuming they all suffered from syncretic WMLs or all WMLs-free. As a result, the area under the curve of our model was 0.787. By integrating PWR, history of diabetes, and age, we could estimate integrated WMLs in hypertensive patients. This study provides a potential tool to identify cerebrovascular disease in patients with hypertension.

Bibliometric analysis of research topics on blood-brain barrier breakdown and cognitive function over the last two decades (2000-2021)

Introduction

Blood-brain barrier (BBB) breakdown is closely associated with cognitive dysfunction. This study aimed to categorize and summarize research topics on the correlation between BBB breakdown and its effects on cognitive function.

Methods

Bibliometric analysis methods were used to quantitatively and qualitatively assess research progress and predict future research hotspots. Relevant publications from the Web of the Science Core Collection were extracted on November 5, 2022 and analyzed to predict trends and hotspots in the field.

Results

We identified 5518 articles published from 2000 to 2021 about the BBB and cognition. The number of manuscripts on this topic increased steadily during this time period, especially after 2013. We found that the number of articles published in China increased gradually and is in second place behind the United States of America (USA). In the research field of BBB breakdown and cognitive function, the USA is still far ahead. Keyword burst detection suggested that cognitive impairment, neurodegeneration disease and neuroinflammation are emerging research hotspots.

Discussion

The mechanisms of BBB integrity breakdown and its effects on the deterioration of cognitive function are complex, and clinical treatment of the affected diseases has been a hot topic in the field over the past 22 years. Looking forward, this body of research is aimed at improving or maintaining patients' cognitive abilities, by finding preventive measures and to provide a basis for finding new treatments of cognitive disorders.

The Effects of SARS-CoV-2 Infection on the Cognitive Functioning of Patients with Pre-Existing Dementia

Background

Cognitive postscripts of COVID-19, codenamed as 'cognitive COVID' or 'brain fog,' characterized by multidomain cognitive impairments, are now being reckoned as the most devastating sequelae of COVID-19. However, the impact on the already demented brain has not been studied.

Objective

We aimed to assess the cognitive functioning and neuroimaging following SARS-CoV-2 infection in patients with pre-existing dementia.

Methods

Fourteen COVID-19 survivors with pre-existing dementia (four with Alzheimer's disease, five with vascular dementia, three with Parkinson's disease dementia, and two with the behavioral variant of frontotemporal dementia) were recruited. All these patients had detailed cognitive and neuroimaging evaluations within three months before suffering from COVID-19 and one year later.

Results

Of the 14 patients, ten required hospitalization. All developed or increased white matter hyperintensities that mimicked multiple sclerosis and small vessel disease. There was a significant increase in fatigue (p = 0.001) and depression (p = 0.016) scores following COVID-19. The mean Frontal Assessment Battery (p < 0.001) and Addenbrooke's Cognitive Examination (p = 0.001) scores also significantly worsened.

Conclusion

The rapid progression of dementia, the addition of further impairments/deterioration of cognitive abilities, and the increase or new appearance of white matter lesion burden suggest that previously compromised brains have little defense to withstand a new insult (i.e., 'second hit' like infection/dysregulated immune response, and inflammation). 'Brain fog' is an ambiguous terminology without specific attribution to the spectrum of post-COVID-19 cognitive sequelae. We propose a new codename, i.e. 'FADE-IN MEMORY' (i.e., Fatigue, decreased Fluency, Attention deficit, Depression, Executive dysfunction, slowed INformation processing speed, and subcortical MEMORY impairment).

The predictive value of fibrinogen in the occurrence of mild cognitive impairment events in patients with diabetic peripheral neuropathy

BACKGROUND

Research suggests that fibrinogen (Fib) is related to mild cognitive impairment (MCI) and diabetic peripheral neuropathy (DPN) and the risk of MCI in patients with DPN is greatly increased, although no studies have evaluated the predictive value of Fib for the risk of MCI in patients with DPN.

METHODS

This prospective observational clinical study enrolled 207 type 2 diabetes mellitus (T2DM) patients, who were divided into diabetes with no neuropathy (102 cases) and diabetes with neuropathy (105 cases) groups. Meanwhile, 90 healthy unrelated subjects were recruited as controls. The incidence of MCI in the DPN patients was followed up for 2 years. Divide patients in the DPN group into subgroups according to whether MCI occur, use multivariate logistic regression to analyze independent factors of MCIs in DPN patients within 2 years, and use ROC curve to analyze the predictive value of Fib for MCI in DPN patients.

RESULTS

Fib levels were significantly higher in diabetic subjects with neuropathy compared with those without (P < 0.001). In further subgroup analysis of DPN patients who were divided according to the occurrence of MCI, baseline data of the MCI subgroup showed Fib levels were higher than that in the non-MCI group while education levels declined (P < 0.001). The education level and increased Fib levels were independent factors for the occurrence of MCI within 2 years after the onset of DPN (OR = 0.769, 95% CI: 0.605 ~ 0.968, P = 0.037; OR = 2.674, 95% CI: 1.094 ~ 3.168, P = 0.002). The ROC curve indicated that the predictive value of Fib was (AUC = 0.764, 95% CI: 0.671 ~ 0.842, P < 0.001).

CONCLUSIONS

Fib may function as a predictor for assessing the risk of MCI in DPN patients.

Vascular dementia: A microglia's perspective

Vascular dementia (VaD) is a second most common form of age-related dementia. It is characterized by cognitive impairment associated with vascular pathology, symptoms mainly caused by cerebral damage due to inadequate blood flow to the brain. The pathogenesis of VaD is complex, and a growing body of literature emphasizes on the involvement of microglia in disease development and progression. Here, we review the current knowledge on the role of microglia in regulating neuroinflammation under the pathogenesis of VaD. The commonly used animal and cell models for understanding the disease pathogenesis were summarized. The mechanisms by which microglia contribute to VaD are multifactorial, and we specifically focus on some of the predominant functions of microglia, including chemotaxis, secretory property, phagocytosis, and its crosstalk with other neurovascular unit cells. Finally, potential therapeutic strategies targeting microglia-modulated neuroinflammation are discussed.

3D finite-element brain modeling of lateral ventricular wall loading to rationalize periventricular white matter hyperintensity locations

Aging-related periventricular white matter hyperintensities (pvWMHs) are a common observation in medical images of the aging brain. The underlying tissue damage is part of the complex pathophysiology associated with age-related microstructural changes and cognitive decline. PvWMH formation is linked to blood-brain barrier dysfunction from cerebral small vessel disease as well as the accumulation of cerebrospinal fluid in periventricular tissue due to progressive denudation of the ventricular wall. In need of a unifying theory for pvWMH etiology, image-based finite-element modeling is used to demonstrate that ventricular expansion from age-related cerebral atrophy and hemodynamic loading leads to maximum mechanical loading of the ventricular wall in the same locations that show pvWMHs. Ventricular inflation, induced via pressurization of the ventricular wall, creates significant ventricular wall stretch and stress on the ependymal cells lining the wall, that are linked to cerebrospinal fluid leaking from the lateral ventricles into periventricular white matter tissue. Eight anatomically accurate 3D brain models of cognitively healthy subjects with a wide range of ventricular shapes are created. For all models, our simulations show that mechanomarkers of mechanical wall loading are consistently highest in pvWMHs locations (p < 0.05). Maximum principal strain, the ependymal cell thinning ratio, and wall curvature are on average 14%, 8%, and 24% higher in pvWMH regions compared to the remaining ventricular wall, respectively. Computational modeling provides a powerful framework to systematically study pvWMH formation and growth with the goal to develop pharmacological interventions in the future.

Dose-response association between plasma homocysteine and white matter lesions in patients with hypertension: a case-control study

White matter lesions (WMLs) are common MRI changes that are indicative of cerebral small vessel disease (CSVD). Elevated plasma homocysteine (Hcy) levels are related to an increased risk of vascular disease. We aimed to analyze the relationship between Hcy levels and WMLs in patients with hypertension. A total of 1961 patients with WMLs and 15,463 patients without WMLs were matched at a 1:1 ratio by age and sex. Hyperhomocysteinemia (HHcy) was defined as an abnormally high level (>15 µmol/l) of Hcy in a plasma sample. In total, 1888 (WML group) and 1888 (No-WMLs group) patients were enrolled, with 51.6% of the sample being male and a mean age of 63 years. Multivariate logistic regression analysis showed a significant association between a higher level of plasma Hcy and a higher prevalence of WMLs (OR 1.03 95% CI, 1.02-1.04) when the Hcy level was used as a continuous variable. Patients with Hcy levels of 15-20 µmol/l (OR 1.54, 95% CI 1.31-1.81) and >20 µmol/l (OR 1.51, 95% CI 1.26-1.82) also had a significantly higher risk of WMLs than patients with Hcy levels <15 µmol/l. Multivariable-adjusted spline regression models showed that the risk of WMLs started to increase only in patients with Hcy levels above 13.85 µmol/l (P < 0.001). In subgroup analyses of WMLs, there was no significant interaction between the Hcy group and subgroup heterogeneity for the prevalence of WMLs (P > 0.05). Our study found a dose-response association between plasma homocysteine levels, especially a Hcy level >13.85 µmol/l, and the prevalence of WMLs, implying that lowering Hcy levels might be a target for prevention.

Primary headaches increase the risk of dementias: An 8-year nationwide cohort study

Background

Headache, a highly prevalent neurological disorder, has consistently been linked with an elevated risk of dementia. However, most studies are focused on the relationship with migraine in limited age groups. Therefore, the objective of this research was to look at the link between various type of headaches and dementias based on longitudinal population-based data.

Methods and results

Participants diagnosed with headache from 2002 to 2005 were selected and major covariates were collected. The diagnoses of Alzheimer’s disease, vascular dementia, and other dementias were observed from 2006 until 2013. The adjusted hazard ratios (aHRs) and 95% confidence intervals (CIs) of dementias according to headache type were calculated by Cox proportional hazards regression. A number of 470,652 participants were observed for a mean of 7.6 years (standard deviation: 1.2), for approximately 3.6 million person-years. Both tension type headache (TTH) and migraine elevated the risk of all-cause dementias (TTH, aHR 1.18, 95% CI 1.13–2.24; migraine, aHR 1.18, 95% CI 1.13–2.24). Headaches had a greater influence in females and non-smokers as a risk factor of dementias. Patients with migraine who consumed alcohol had a higher risk of dementia, however this was not true with TTH patients. Among participants without comorbidities, TTH patients were more susceptible to dementia than migraine patients. Headache patients had a higher proportion of females regardless of headache type and approximately 1.5 times more individuals had three or more comorbidities compared to those without headache.

Conclusions

Headache could be an independent predictor for subsequent dementia risk. Future studies should focus on clarifying pathogenic pathways and possible dementia-related preventive measures in headache populations.

Cerebral small vessel disease: Pathological mechanisms and potential therapeutic targets

Cerebral small vessel disease (CSVD) represents a diverse cluster of cerebrovascular diseases primarily affecting small arteries, capillaries, arterioles and venules. The diagnosis of CSVD relies on the identification of small subcortical infarcts, lacunes, white matter hyperintensities, perivascular spaces, and microbleeds using neuroimaging. CSVD is observed in 25% of strokes worldwide and is the most common pathology of cognitive decline and dementia in the elderly. Still, due to the poor understanding of pathophysiology in CSVD, there is not an effective preventative or therapeutic approach for CSVD. The most widely accepted approach to CSVD treatment is to mitigate vascular risk factors and adopt a healthier lifestyle. Thus, a deeper understanding of pathogenesis may foster more specific therapies. Here, we review the underlying mechanisms of pathological characteristics in CSVD development, with a focus on endothelial dysfunction, blood-brain barrier impairment and white matter change. We also describe inflammation in CSVD, whose role in contributing to CSVD pathology is gaining interest. Finally, we update the current treatments and preventative measures of CSVD, as well as discuss potential targets and novel strategies for CSVD treatment.

[Association of sudden sensorineural hearing loss and its prognosis with the brain white matter hyperintensity]

Objective:To explore the relationship between white matter hyperintensity（WMH） and sudden sensorineural hearing loss（SSHL） and evaluate the influence of WMH on the prognosis of SSHL. Methods:Fifty hospitalized unilateral SSHL patients and 50 age and gender matched routine physical examination individuals without SSHL history from June 2019 to June 2020 were included for a case-control study. All included subjects underwent 3.0 Tesla cranial magnetic resonance examination, and the Fazekas scale was applied to evaluate periventricular white matter hyperintense（PVWMH） and deep white matter hyperintense（DWMH）. Fazekas score and distribution proportions of Fazekas score was compared between SSHL and control. Ordered logistic regression was used to study the relationship between prognosis of SSHL and WMH. Results:The Fazekas score of WMH in SSHL group was significantly higher than that of control group（PVWMH: P=0.004, DWMH: P=0.010）; There was a significant difference in the distribution proportions of Fazekas scores between SSHL and control（PVWMH: P=0.036, DWMH: P=0.047）; The results of ordered logistic regression showed that patients without WMH（Fazekas=0） is an independent predictor of good prognosis in SSHL（P=0.025, OR=12.779）. Conclusion:The prevalence of WMH in SSHL patients was higher than that of control. SSHL patients without WMH has a better prognosis than those with WMH.

Vascular pathology and pathogenesis of cognitive impairment and dementia in older adults

It is well recognized that brains of older people often harbor cerebrovascular disease pathology including vessel disease and vascular-related tissue injuries and that this is associated with vascular cognitive impairment and contributes to dementia. Here we review vascular pathologies, cognitive impairment, and dementia. We highlight the importance of mixed co-morbid AD/non-AD neurodegenerative and vascular pathology that has been collected in multiple clinical pathologic studies, especially in community-based studies. We also provide an update of vascular pathologies from the Rush Memory and Aging Project and Religious Orders Study cohorts with special emphasis on the differences across age in persons with and without dementia. Finally, we discuss neuropathological perspectives on the interpretation of clinical-pathological studies and emerging data in community-based studies.

c-Abl-induced Olig2 phosphorylation regulates the proliferation of oligodendrocyte precursor cells

Oligodendrocytes (OLs), the myelinating cells in the central nervous system (CNS), are differentiated from OL progenitor cells (OPCs). The proliferation of existing OPCs is indispensable for myelination during CNS development and remyelination in response to demyelination stimulation. The transcription factor Olig2 is required for the specification of OLs and is expressed in the OL lineage. However, the post-translational modification of Olig2 in the proliferation of OPCs is poorly understood. Herein, we identified that c-Abl directly phosphorylates Olig2 mainly at the Tyr137 site, and that Olig2 phosphorylation is essential for OPC proliferation. The expression levels of c-Abl gradually decreased with brain development; moreover, c-Abl was highly expressed in OPCs. OL-specific c-Abl knockout at the developmental stage led to an insufficient proliferation of OPCs, a decreased expression of myelin-related genes, and myelination retardation. Accordingly, a c-Abl-specific kinase inhibitor suppressed OPC proliferation in vitro. Furthermore, we observed that OL-specific c-Abl knockout reduced OPC proliferation and remyelination in a cuprizone model of demyelination. In addition, we found that nilotinib, a clinically used c-Abl inhibitor, decreased the expression of myelin basic protein (Mbp) and motor coordination in mice, indicating a neurological side effect of a long-term administration of the c-Abl inhibitor. Thus, we identified the important role of c-Abl in OLs during developmental myelination and remyelination in a disease model.

Vascular cognitive impairment and dementia: An early career researcher perspective

The field of vascular contributions to cognitive impairment and dementia (VCID) is evolving rapidly. Research in VCID encompasses topics aiming to understand, prevent, and treat the detrimental effects of vascular disease burden in the human brain. In this perspective piece, early career researchers (ECRs) in the field provide an overview of VCID, discuss past and present efforts, and highlight priorities for future research. We emphasize the following critical points as the field progresses: (a) consolidate existing neuroimaging and fluid biomarkers, and establish their utility for pharmacological and non-pharmacological interventions; (b) develop new biomarkers, and new non-clinical models that better recapitulate vascular pathologies; (c) amplify access to emerging biomarker and imaging techniques; (d) validate findings from previous investigations in diverse populations, including those at higher risk of cognitive impairment (e.g., Black, Hispanic, and Indigenous populations); and (e) conduct randomized controlled trials within diverse populations with well-characterized vascular pathologies emphasizing clinically meaningful outcomes.

Plasma aldosterone concentration is associated with white matter lesions in patients with primary aldosteronism

PURPOSE

Primary aldosteronism (PA) is the most frequent form of secondary hypertension. Hypertension is a risk factor for cognitive decline and dementia. White matter lesions (WMLs) are linked to vascular risk factors, which increase the risk of dementia. We aimed to analyze the association of PA-related parameters and WMLs in patients with PA.

METHODS

We conducted a retrospective analysis of all patients with PA in the Hypertension Center of the People's Hospital of Xinjiang Uygur Autonomous Region from January 1, 2011 to April 1, 2021. We analyzed the relationship between plasma aldosterone concentration (PAC), plasma renin activity (PRA), aldosterone-renin ratio (ARR), serum potassium, and WMLs.

RESULTS

We enrolled 138 patients with WMLs and matched these to controls without WMLs at a 1:4 ratio. Among the analytic sample (N = 711) with ages ranging from 30 to 64 years, 69% were male. In the logistic regression analysis, PAC, PRA and serum potassium were treated as continuous variables. The results showed that PAC (OR 1.04, 95% CI 1.01, 1.06, P = 0.008) was positively associated with the risk of WMLs, and serum potassium (OR 0.26, 95% CI 0.16, 0.44, P < 0.001) was inversely associated with the risk of WMLs. PRA (OR 0.86, 95% CI 0.68, 1.08, P = 0.384) was not associated with the risk of WMLs after adjusting for confounders. The results of restricted cubic splines showed the dose-response association between increasing PAC, ARR, decreasing serum potassium, and the risk of WMLs. We also divided PAC, ARR and serum potassium into two groups according to the result of restricted cubic splines. After adjusting for confounders, patients who were in Q2 (≥23.12 ng/dl) of PAC (OR 2.07, 95% CI 1.36, 3.15), Q2 (≥56.81 (ng/dl per ng/ml*h) of ARR (OR 1.82, 95% CI 1.22, 2.72) and Q2 (≤3.58 mmol/l) of serum potassium (OR 2.99, 95% CI 1.95, 4.50) had a significantly higher risk of WMLs than their counterparts. In stratified analyses, there was no evidence of subgroup heterogeneity regarding the change in the risk of WMLs (P > 0.05 for interaction for all).

CONCLUSION

Our results suggested that the PAC and serum potassium were related to the risk of WMLs in patients with PA. In particular, PAC ≥23.12 ng/dl significantly increased the risk of WMLs in patients with PA.

Vasculocentric Axonal NfH in Small Vessel Disease

Cerebral small vessel disease (SVD) causes lacunar stroke and vascular cognitive impairment in older people. The pathogenic pathways from vessel pathology to parenchymal damage in SVD are unknown. Neurofilaments are axonal structural proteins. Neurofilament-light (NfL) is an emerging biomarker for neurological disease. Here, we examined the high molecular weight form neurofilament-heavy (NfH) and quantified a characteristic pattern of peri-arterial (vasculocentric) NfH labeling. Subcortical frontal and parietal white matter from young adult controls, aged controls, and older people with SVD or severe Alzheimer disease (n = 52) was immunohistochemically labeled for hyperphosphorylated NfH (pNfH). The extent of pNfH immunolabeling and the degree of vasculocentric axonal pNfH were quantified. Axonal pNfH immunolabeling was sparse in young adults but a common finding in older persons (controls, SVD, or AD). Axonal pNfH was often markedly concentrated around small penetrating arteries. This vasculocentric feature was more common in older people with SVD than in those with severe AD (p = 0.004). We conclude that axonal pNfH is a feature of subcortical white matter in aged brains. Vasculocentric axonal pNfH is a novel parenchymal lesion that is co-located with SVD arteriopathy and could be a consequence of vessel pathology.

Neuropathology of Vascular Brain Health: Insights From Ex Vivo Magnetic Resonance Imaging-Histopathology Studies in Cerebral Small Vessel Disease

Sporadic cerebral small vessel disease (SVD) is a major contributor to vascular cognitive impairment and dementia in the aging human brain. On neuropathology, sporadic SVD is characterized by abnormalities to the small vessels of the brain predominantly in the form of cerebral amyloid angiopathy and arteriolosclerosis. These pathologies frequently coexist with Alzheimer disease changes, such as plaques and tangles, in a single brain. Conversely, during life, magnetic resonance imaging (MRI) only captures the larger manifestations of SVD in the form of parenchymal brain abnormalities. There appears to be a major knowledge gap regarding the underlying neuropathology of individual MRI-detectable SVD abnormalities. Ex vivo MRI in postmortem human brain tissue is a powerful tool to bridge this gap. This review summarizes current insights into the histopathologic correlations of MRI manifestations of SVD, their underlying cause, presumed pathophysiology, and associated secondary tissue injury. Moreover, we discuss the advantages and limitations of ex vivo MRI-guided histopathologic investigations and make recommendations for future studies.

The Potential Impact of Neuroimaging and Translational Research on the Clinical Management of Lacunar Stroke

Lacunar infarcts represent one of the most frequent subtypes of ischemic strokes and may represent the first recognizable manifestation of a progressive disease of the small perforating arteries, capillaries, and venules of the brain, defined as cerebral small vessel disease. The pathophysiological mechanisms leading to a perforating artery occlusion are multiple and still not completely defined, due to spatial resolution issues in neuroimaging, sparsity of pathological studies, and lack of valid experimental models. Recent advances in the endovascular treatment of large vessel occlusion may have diverted attention from the management of patients with small vessel occlusions, often excluded from clinical trials of acute therapy and secondary prevention. However, patients with a lacunar stroke benefit from early diagnosis, reperfusion therapy, and secondary prevention measures. In addition, there are new developments in the knowledge of this entity that suggest potential benefits of thrombolysis in an extended time window in selected patients, as well as novel therapeutic approaches targeting different pathophysiological mechanisms involved in small vessel disease. This review offers a comprehensive update in lacunar stroke pathophysiology and clinical perspective for managing lacunar strokes, in light of the latest insights from imaging and translational studies.

Adiponectin Levels Are Associated with White Matter Lesions (WMLs) and Cognitive Impairment

METHOD

In the present study, 126 patients, 90 cases in the WML group and 36 cases in the control group, were analyzed to explore the relationship between adiponectin and WMLs. All patients underwent an MRI scan to assess whether white matter lesions happened. And the serum levels of adiponectin were detected by ELISA.

RESULTS

In this study, according to Fazekas criteria, WMLs were divided into different severity groups. With the increase of WML score, the level of adiponectin decreased, and linear correlation analysis shows that adiponectin is negatively correlated with the severity of white matter lesions (p < 0.001). And adiponectin level was significantly positively correlated with MoCA score (p < 0.05). Moreover, adiponectin in the WMLs combined with the cognitive impairment group was significantly reduced (p < 0.01).

CONCLUSION

The level of adiponectin is independently associated with WMLs and cognitive function, which suggests that adiponectin may be a protective factor for WMLs and cognitive function.

Innate Immune Anti-Inflammatory Response in Human Spontaneous Intracerebral Hemorrhage

Background and Purpose

Spontaneous intracerebral hemorrhage (sICH) is a common form of hemorrhagic stroke, with high mortality and morbidity. Pathophysiological mechanisms in sICH are poorly understood and treatments limited. Neuroinflammation driven by microglial-macrophage activation contributes to brain damage post-sICH. We aim to test the hypothesis that an anti-inflammatory (repair) process occurs in parallel with neuroinflammation in clinical sICH.

Methods

We performed quantitative analysis of immunohistochemical markers for microglia and macrophages (Iba1, CD68, TMEM119, CD163, and CD206) in brain tissue biospecimens 1 to 12 days post-sICH and matched control cases. In a parallel, prospective group of patients, we assayed circulating inflammatory markers (CRP [C-reactive protein], total white cell, and monocyte count) over 1 to 12 days following sICH.

Results

In 27 supratentorial sICH cases (n=27, median [interquartile range] age: 59 [52–80.5], 14F/13M) all microglia-macrophage markers increased post-sICH, relative to control brains. Anti-inflammatory markers (CD163 and CD206) were elevated alongside proinflammatory markers (CD68 and TMEM119). CD163 increased progressively post-sICH (15.0-fold increase at 7–12 days, P<0.001). CD206 increased at 3 to 5 days (5.2-fold, P<0.001) then returned to control levels at 7 to 12 days. The parenchymal immune response combined brain-derived microglia (TMEM119 positive) and invading monocyte-derived macrophages (CD206 positive). In a prospective sICH patient cohort (n=26, age 74 [66–79], National Institutes of Health Stroke Scale on admission: 8 [4–17]; 14F/12M) blood CRP concentration and monocyte density (but not white blood cell) increased post-sICH. CRP increased from 0 to 2 to 3 to 5 days (8.3-fold, P=0.020) then declined at 7 to 12 days. Monocytes increased from 0 to 2 to 3 to 5 days (1.8-fold, P<0.001) then declined at 7 to 12 days.

Conclusions

An anti-inflammatory pathway, enlisting native microglia and blood monocytes, occurs alongside neuroinflammation post-sICH. This novel pathway offers therapeutic targets and a window of opportunity (3–5 days post-sICH) for delivery of therapeutics via invading monocytes.

Cardiovascular co-morbidities, inflammation and cerebral small vessel disease

Cerebral small vessel disease (cSVD) is the most common cause of vascular cognitive impairment and affects all levels of the brain's vasculature. Features include diverse structural and functional changes affecting small arteries and capillaries that lead to a decline in cerebral perfusion. Due to an aging population, incidence of cerebral small vessel disease (cSVD) is continually rising. Despite its prevalence and its ability to cause multiple debilitating illnesses, such as stroke and dementia, there are currently no therapeutic strategies for the treatment of cSVD. In the healthy brain, interactions between neuronal, vascular and inflammatory cells are required for normal functioning. When these interactions are disturbed, chronic pathological inflammation can ensue. The interplay between cSVD and inflammation has attracted much recent interest and this review discusses chronic cardiovascular diseases, particularly hypertension, and explores how the associated inflammation may impact on the structure and function of the small arteries of the brain in cSVD. Molecular approaches in animal studies are linked to clinical outcomes in patients and novel hypotheses regarding inflammation and cSVD are proposed that will hopefully stimulate further discussion and study in this important area.

Leukoaraiosis is associated with clinical symptom severity, poor neurological function prognosis and stroke recurrence in mild intracerebral hemorrhage: a prospective multi-center cohort study

Leukoaraiosis (LA) results from ischemic injury in small cerebral vessels, which may be attributable to decreased vascular density, reduced cerebrovascular angiogenesis, decreased cerebral blood flow, or microcirculatory dysfunction in the brain. In this study, we enrolled 357 patients with mild intracerebral hemorrhage (ICH) from five hospitals in China and analyzed the relationships between LA and clinical symptom severity at admission, neurological function prognosis at 3 months, and 1-year stroke recurrence. Patients were divided into groups based on Fazekas scale scores: no LA (n = 83), mild LA (n = 64), moderate LA (n = 98) and severe LA (n = 112). More severe LA, larger hematoma volume, and higher blood glucose level at admission were associated with more severe neurological deficit. More severe LA, older age and larger hematoma volume were associated with worse neurological function prognosis at 3 months. In addition, moderate-to-severe LA, admission glucose and symptom-free cerebral infarction were associated with 1-year stroke recurrence. These findings suggest that LA severity may be a potential marker of individual ICH vulnerability, which can be characterized by poor tolerance to intracerebral attack or poor recovery ability after ICH. Evaluating LA severity in patients with mild ICH may help neurologists to optimize treatment protocols. This study was approved by the Ethics Committee of Ruijin Hospital Affiliated to Shanghai Jiao Tong University (approval No. 12) on March 10, 2011.

Value of Magnetic Resonance Diffusion Tensor Imaging Combined with Quantitative Electroencephalogram in Diagnosis of Neurocognitive Impairment in Patients with White Matter Demyelination

This paper aimed to explore the clinical value of combined adoption of magnetic resonance diffusion tensor imaging (DTI) and quantitative electroencephalogram (QEEG) in assessing microstructure changes and mild neurocognitive dysfunction in patients with white matter demyelination. 128 cases of white matter demyelination admitted to the hospital from October 2018 to October 2019 were rolled into the research group, and 100 healthy patients physically examined during the same period were rolled into the control (ctrl) group. QEEG and magnetic resonance DTI examinations were performed for all patients. The wave power of δ, θ, α, and β and the ratio of α/θ and (δ + θ)/(α + β) were recorded. The FA values of white matter fibers in different brain areas were measured, and the Montreal Cognitive Assessment (MoCA) and Addenbrooke Cognitive Evaluation rating (ACE-R) were adopted to assess the neurocognitive function of patients. It was found that the dominant frequency of each brain area in the research group was 8-9 Hz slow α wave. In contrast with the ctrl, the α wave and α/θ values in the research group were lower, while θ wave and δ + θ/α + β values were higher (P < 0.05); the scores of ACE-R and MoCA were lower (P < 0.01); the fractional anisotropy (FA) values of the right frontal lobe white matter (0.335 ± 0.068), the left temporal lobe white matter (0.391 ± 0.032), and the corpus callosum knee white matter (0.658 ± 0.053) were lower (P < 0.05). The FA values of these three areas were positively correlated with attention and calculation, memory, and memory of MoCA scale, respectively (P < 0.05). The FA value of the right frontal white matter was positively correlated with the attention and calculation score of the ACE-R scale (P < 0.05). In conclusion, magnetic resonance DTI combined with QEEG could reflect the microstructural changes of white matter, which may be associated with mild neurocognitive impairment. The primary objective of the study was to explore the clinical value of combined adoption of magnetic resonance DTI and QEEG in assessing microstructure changes and mild neurocognitive dysfunction in patients with white matter demyelination, expected to provide a theoretical basis for the treatment of white matter demyelination.

Leukoaraiosis and acute ischemic stroke

Ischaemic stroke is characterized by high morbidity, high disability rate, high mortality and high recurrence rate, which can have a grave impact on the quality of life of the patients and consequently becomes an economic burden on their families and society. With the developments in imaging technology in recent years, patients with acute cerebral infarction are predominantly more likely to be diagnosed with leukoaraiosis (LA). LA is a common degenerative disease of the nervous system, which is related to cognitive decline, depression, abnormal gait, ischaemic stroke and atherosclerosis. The aetiology of LA is not clear and there is no gold standard for imaging assessment. Related studies have shown that LA has an adverse effect on the prognosis of cerebral infarction, but some experts have contrary beliefs. Hence, we undertook the present review of the literature on the mechanism and the effect of LA on the prognosis of patients with acute ischaemic stroke.

Emerging role of white matter lesions in cerebrovascular disease

White matter lesions have been implicated in the setting of stroke, dementia, intracerebral haemorrhage, several other cerebrovascular conditions, migraine, various neuroimmunological diseases like multiple sclerosis, disorders of metabolism, mitochondrial diseases and others. While much is understood vis a vis neuroimmunological conditions, our knowledge of the pathophysiology of these lesions, and their role in, and implications to, management of cerebrovascular diseases or stroke, especially in the elderly, are limited. Several clinical assessment tools are available for delineating white matter lesions in clinical practice. However, their incorporation into clinical decision-making and specifically prognosis and management of patients is suboptimal for use in standards of care. This article sought to provide an overview of the current knowledge and recent advances on pathophysiology, as well as clinical and radiological assessment, of white matter lesions with a focus on its development, progression and clinical implications in cerebrovascular diseases. Key indications for clinical practice and recommendations on future areas of research are also discussed. Finally, a conceptual proposal on putative mechanisms underlying pathogenesis of white matter lesions in cerebrovascular disease has been presented. Understanding of pathophysiology of white matter lesions and how they mediate outcomes is important to develop therapeutic strategies.

Blood-brain barrier leakage at baseline and cognitive decline in cerebral small vessel disease: a 2-year follow-up study

Blood–brain barrier (BBB) dysfunction is one of the pathophysiological mechanisms in cerebral small vessel disease (SVD). Previously, it was shown that BBB leakage volume is larger in patients with SVD compared with controls. In this study, we investigated the link between BBB leakage and cognitive decline over 2 years in patients with cSVD. At baseline, 51 patients with clinically overt cSVD (lacunar stroke or mild vascular cognitive impairment) received a dynamic contrast-enhanced MRI scan to quantify BBB permeability in the normal-appearing white matter (NAWM), white matter hyperintensities (WMH), cortical grey matter (CGM), and deep grey matter (DGM). Cognitive function in the domain executive function, information processing speed, and memory was measured in all patients at baseline and after 2 years. The association between baseline BBB leakage and cognitive decline over 2 years was determined with multivariable linear regression analysis, corrected for age, sex, educational level, baseline WMH volume, and baseline brain volume. Regression analyses showed that higher baseline leakage volume and rate in the NAWM and CGM were significantly associated with increased overall cognitive decline. Furthermore, higher baseline leakage volume in the NAWM and CGM, and higher baseline leakage rate in the CGM were significantly associated with increased decline in executive function. This longitudinal study showed that higher BBB leakage at baseline is associated with stronger cognitive decline, specifically in executive function, over 2 years of follow-up in patients with cSVD. These results emphasize the key role of BBB disruption in the pathophysiology and clinical progression of cSVD.

NXP031 Improves Cognitive Impairment in a Chronic Cerebral Hypoperfusion-Induced Vascular Dementia Rat Model through Nrf2 Signaling

Vascular dementia (VaD) is a progressive cognitive impairment caused by a reduced blood supply to the brain. Chronic cerebral hypoperfusion (CCH) is one cause of VaD; it induces oxidative stress, neuroinflammation, and blood-brain barrier (BBB) disruption, damaging several brain regions. Vitamin C plays a vital role in preventing oxidative stress-related diseases induced by reactive oxygen species, but it is easily oxidized and loses its antioxidant activity. To overcome this weakness, we have developed a vitamin C/DNA aptamer complex (NXP031) that increases vitamin C's antioxidant efficacy. Aptamers are short single-stranded nucleic acid polymers (DNA or RNA) that can interact with their corresponding target with high affinity. We established an animal model of VaD by permanent bilateral common carotid artery occlusion (BCCAO) in 12 week old Wistar rats. Twelve weeks after BCCAO, we injected NXP031 into the rats intraperitoneally for two weeks at moderate (200 mg/4 mg/kg) and high concentrations (200 mg/20 mg/kg). NXP031 administration alleviates cognitive impairment, microglial activity, and oxidative stress after CCH. NXP031 increased the expression of basal lamina (laminin), endothelial cell (RECA-1, PECAM-1), and pericyte (PDGFRβ); these markers maintain the BBB integrity. We found that NXP031 administration activated the Nrf2-ARE pathway and increased the expression of SOD-1 and GSTO1/2. These results suggest that this new aptamer complex, NXP031, could be a therapeutic intervention in CCH-induced VaD.

Amylin Dyshomeostasis Hypothesis: Small Vessel-Type Ischemic Stroke in the Setting of Type-2 Diabetes

Recent histological analyses of human brains show that small vessel-type injuries in the setting of type-2 diabetes colocalize with deposits of amylin, an amyloid-forming hormone secreted by the pancreas. Amylin inclusions are also identified in circulating red blood cells in people with type-2 diabetes and stroke or cardiovascular disease. In laboratory models of type-2 diabetes, accumulation of aggregated amylin in blood and the cerebral microvasculature induces brain microhemorrhages and reduces cerebral blood flow leading to white matter ischemia and neurological deficits. At the cellular level, aggregated amylin causes cell membrane lipid peroxidation injury, downregulation of tight junction proteins, and activation of proinflammatory signaling pathways which, in turn, induces macrophage activation and macrophage infiltration in vascular areas positive for amylin deposition. We review each step of this cascade based on experimental and clinical evidence and propose the hypothesis that systemic amylin dyshomeostasis may underlie the disparity between glycemic control and stroke risk and may be a therapeutic target to reduce the risk of small vessel ischemic stroke in patients with type-2 diabetes.

Fibrinogen is an Independent Risk Factor for White Matter Hyperintensities in CADASIL but not in Sporadic Cerebral Small Vessel Disease Patients

The relationship between fibrinogen and white matter hyperintensities (WMHs) are inconsistent. Whether there are different relationships between WMHs and fibrinogen in disparate subtypes of cerebral small vessel disease (CSVD) remains unknown. Here, we investigated the roles of plasma fibrinogen in sporadic CSVD (sCSVD) and Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL) patients. We performed a cross-sectional study that included 74 CSVD patients (19 CADASIL and 55 sporadic) and 74 age- and gender-matched healthy controls (HCs). Plasma fibrinogen was determined, and the severity of WMHs in CSVD patients was rated according to Fazekas scales. Univariate analysis and ordinal logistic regression were performed to evaluate the relationship between fibrinogen and the severity of WMHs in CSVD. Both CADASIL and sCSVD patients showed significantly higher plasma fibrinogen levels than HCs. No significant difference in the plasma fibrinogen level was observed between CADASIL and sCSVD. Univariate analysis and ordinal logistic regression indicated that fibrinogen is an independent risk factor for the severity of WMHs in CADASIL patients (odds ratio [OR] =1.064; 95% Confidence interval (CI, 1.004-1.127); p =0.037). However, age (odds ratio [OR] =1.093; 95% CI (1.033-1.156); P = 0.002), but not fibrinogen (odds ratio [OR] =1.004; 95% CI (0.997-1.011); P=0.262), is an independent risk factor for the severity of WMHs in sCSVD patients. Our results suggest that high levels of plasma fibrinogen are associated with the severity of WMHs in CADASIL but not in sCSVD patients, indicating that the role of fibrinogen may be different in disparate subtypes of CSVD. A better understanding of fibrinogen may yield insights into the pathogenesis of CSVD.

Correlations in post-mortem imaging-histopathology studies of sporadic human cerebral small vessel disease: A systematic review

AIMS

Sporadic human cerebral small vessel disease (SVD) commonly causes stroke and dementia but its pathogenesis is poorly understood. There are recognised neuroimaging and histopathological features. However, relatively few studies have examined the relationship between the radiological and pathological correlates of SVD; better correlation would promote greater insight into the underlying biological changes.

METHODS

We performed a systematic review to collate and appraise the information derived from studies that correlated histological with neuroimaging-defined SVD lesions. We searched for studies describing post-mortem imaging and histological tissue examination in adults, extracted data from published studies, categorised the information and compiled this narrative.

RESULTS

We identified 38 relevant studies, including at least 1146 subjects, 342 of these with SVD: 29 studies focussed on neuroradiological white matter lesions (WML), six on microinfarcts and three on dilated perivascular spaces (PVS) and lacunes. The histopathology terminology was diverse with few robust definitions. Reporting and methodology varied widely between studies, precluding formal meta-analysis. PVS and 'oedema' were frequent findings in WML, being described in at least 94 and 18 radiological WML, respectively, in addition to myelin pallor. Histopathological changes extended beyond the radiological lesion margins in at least 33 radiological WML. At least 43 radiological lesions not seen pathologically and at least 178 histological lesions were not identified on imaging.

CONCLUSIONS

Histopathological assessment of human SVD is hindered by inconsistent methodological approaches and unstandardised definitions. The data from this systematic review will help to develop standardised definitions to promote consistency in human SVD research.

Non-Invasive Evaluation of Cerebral Microvasculature Using Pre-Clinical MRI: Principles, Advantages and Limitations

Alterations to the cerebral microcirculation have been recognized to play a crucial role in the development of neurodegenerative disorders. However, the exact role of the microvascular alterations in the pathophysiological mechanisms often remains poorly understood. The early detection of changes in microcirculation and cerebral blood flow (CBF) can be used to get a better understanding of underlying disease mechanisms. This could be an important step towards the development of new treatment approaches. Animal models allow for the study of the disease mechanism at several stages of development, before the onset of clinical symptoms, and the verification with invasive imaging techniques. Specifically, pre-clinical magnetic resonance imaging (MRI) is an important tool for the development and validation of MRI sequences under clinically relevant conditions. This article reviews MRI strategies providing indirect non-invasive measurements of microvascular changes in the rodent brain that can be used for early detection and characterization of neurodegenerative disorders. The perfusion MRI techniques: Dynamic Contrast Enhanced (DCE), Dynamic Susceptibility Contrast Enhanced (DSC) and Arterial Spin Labeling (ASL), will be discussed, followed by less established imaging strategies used to analyze the cerebral microcirculation: Intravoxel Incoherent Motion (IVIM), Vascular Space Occupancy (VASO), Steady-State Susceptibility Contrast (SSC), Vessel size imaging, SAGE-based DSC, Phase Contrast Flow (PC) Quantitative Susceptibility Mapping (QSM) and quantitative Blood-Oxygenation-Level-Dependent (qBOLD). We will emphasize the advantages and limitations of each strategy, in particular on applications for high-field MRI in the rodent's brain.

Plasma lipids are associated with white matter microstructural changes and axonal degeneration

Dislipidemia is a risk factor for cognitive impairment. We studied the association between interindividual variability of plasma lipids and white matter (WM) microstructure, using diffusion tensor imaging (DTI) in 273 healthy adults. Special focus was placed on 7 regions of interest (ROI) which are structural components of cognitive neurocircuitry. We also investigated the effect of plasma lipids on cerebrospinal fluid (CSF) neurofilament light chain (NfL), an axonal degeneration marker. Low density lipoprotein (LDL) and triglyceride (TG) levels showed a negative association with axial diffusivity (AxD) in multiple regions. High density lipoproteins (HDL) showed a positive correlation. The association was independent of Apolipoprotein E (APOE) genotype, blood pressure or use of statins. LDL moderated the relation between NfL and AxD in the body of the corpus callosum (p = 0.041), right cingulum gyrus (p = 0.041), right fornix/stria terminalis (p = 0.025) and right superior longitudinal fasciculus (p = 0.020) and TG in the right inferior longitudinal fasciculus (p = 0.004) and left fornix/stria terminalis (p = 0.001). We conclude that plasma lipids are associated to WM microstructural changes and axonal degeneration and might represent a risk factor in the transition from healthy aging to disease.

Baseline Blood-Brain Barrier Leakage and Longitudinal Microstructural Tissue Damage in the Periphery of White Matter Hyperintensities

OBJECTIVE

To investigate the 2-year change in parenchymal diffusivity, a quantitative marker of microstructural tissue condition, and the relationship with baseline blood-brain barrier (BBB) permeability, in tissue at risk, i.e., the perilesional zone surrounding white matter hyperintensities (WMH) in patients with cerebral small vessel disease (cSVD).

METHODS

Patients with sporadic cSVD (lacunar stroke or mild vascular cognitive impairment) underwent 3T MRI at baseline, including dynamic contrast-enhanced MRI to quantify BBB permeability (i.e., leakage volume and rate) and intravoxel incoherent motion imaging (IVIM), a diffusion technique that provides parenchymal diffusivity D. After 2 years, IVIM was repeated. We assessed the relation between BBB leakage measures at baseline and change in parenchymal diffusivity (∆D) over 2 years in the perilesional zones (divided in 2-mm contours) surrounding WMH.

RESULTS

We analyzed 43 patients (age 68 ± 12 years, 58% male). In the perilesional zones, ∆D increased 0.10% (confidence interval [CI] 0.07-0.013%) (p < 0.01) per 2 mm closer to the WMH. Furthermore, ∆D over 2 years showed a positive correlation with both baseline BBB leakage volume (r = 0.29 [CI 0.06-0.52], p = 0.013) and leakage rate (r = 0.24 [CI 0.02-0.47], p = 0.034).

CONCLUSION

BBB leakage at baseline is related to the 2-year change in parenchymal diffusivity in the perilesional zone of WMH. These results support the hypothesis that BBB impairment might play an early role in subsequent microstructural white matter degeneration as part of the pathophysiology of cSVD.

The Impact of Disease Comorbidities in Alzheimer's Disease

A wide range of comorbid diseases is associated with Alzheimer's disease (AD), the most common neurodegenerative disease worldwide. Evidence from clinical and molecular studies suggest that chronic diseases, including diabetes, cardiovascular disease, depression, and inflammatory bowel disease, may be associated with an increased risk of AD in different populations. Disruption in several shared biological pathways has been proposed as the underlying mechanism for the association between AD and these comorbidities. Notably, inflammation is a common dysregulated pathway shared by most of the comorbidities associated with AD. Some drugs commonly prescribed to patients with diabetes and cardiovascular disease have shown promising results in AD patients. Systems-based biology studies have identified common genetic factors and dysregulated pathways that may explain the relationship of comorbid disorders in AD. Nonetheless, the precise mechanisms for the occurrence of disease comorbidities in AD are not entirely understood. Here, we discuss the impact of the most common comorbidities in the clinical management of AD patients.

Positive Association Between Plasma Aldosterone Concentration and White Matter Lesions in Patients With Hypertension

BACKGROUND AND OBJECTIVE

White matter lesions (WMLs) are imaging changes in MRI of cerebral small vessel disease associated with vascular risk factors, increasing the risk of dementia, depression, and stroke. Aldosterone (ALD) or activation of mineralocorticoid receptor (MR) causes cerebrovascular injury in a mouse model. We aimed to analyze the relationship between ALD and WMLs in a population with hypertension.

METHODS

We conducted a retrospective review of all patients screened for causes of secondary hypertension. We enrolled 547 patients with WMLs and matched these to controls without WMLs at a 1:1 ratio. White matter lesion load was assessed by using a modified Scheltens' scale.

RESULTS

Among the analytic sample (N = 1,094) with ages ranging from 30 to 64 years, 62.2% were male. We divided plasma ALD concentration (PAC), plasma renin activity (PRA), and ALD-renin ratio (ARR) into the third tertile (Q3), second tertile (Q2), and first tertile (Q1). We also analyzed them simultaneously as continuous variables. Multivariate logistic regression analysis showed that participants in Q3 (>17.26 ng/dl) of PAC (OR 1.59, 95% CI 1.15, 2.19), Q3 (<0.80 ng/dl) of PRA (OR 2.50, 95% CI 1.81, 3.44), and Q3 (>18.59 ng/dl per ng/ml*h) of ARR (OR 2.90, 95% CI 2.10, 4.01) had a significantly higher risk of WMLs than those in Q1 (<12.48) of PAC, Q1 (>2.19) of PRA, and Q1 (<6.96) of ARR. In linear regression analysis, we separately analyzed the correlation between the modified Scheltens' scale score and log(PAC) (β = 2.36; 95% CI 1.30, 3.41; p < 0.001), log(PRA) (β = -1.76; 95% CI -2.09, -1.43; p < 0.001), and log(ARR) (β = 1.86; 95% CI 1.55, 2.17; p < 0.001), which were all significantly correlated with white matter lesion load, after adjusting for confounding factors. Simple mediation analyses showed that systolic blood pressure (SBP) or diastolic blood pressure (DBP) mediated -3.83% or -2.66% of the association between PAC and white matter lesion load, respectively. In stratified analyses, there was no evidence of subgroup heterogeneity concerning the change in the risk of WMLs (p > 0.05 for interaction for all).

CONCLUSION

Higher PAC, especially in PAC >17.26 ng/dl, increased the risk of WMLs. PAC was positively associated with white matter lesion load independent of SBP or DBP.