Periventricular venous collagenosis: association with leukoaraiosis

Advancements in investigating the role of cerebral small vein loss in Alzheimer's disease-related pathological changes

Alzheimer's disease (AD) is the prevailing type of dementia in the elderly, yet a comprehensive comprehension of its precise underlying mechanisms remains elusive. The investigation of the involvement of cerebral small veins in the advancement of AD has yet to be sufficiently explored in previous studies, primarily due to constraints associated with pathological staining techniques. However, recent research has provided valuable insights into multiple pathophysiological occurrences concerning cerebral small veins in AD, which may manifest sequentially, concurrently, or in a self-perpetuating manner. These events are presumed to be among the initial processes in the disease's progression. The impact of cerebral small vein loss on amyloid beta (Aβ) clearance through the glial lymphatic system is noteworthy. There exists a potential interdependence between collagen deposition and Aβ deposition in cerebral small veins. The compromised functionality of cerebral small veins can result in decreased cerebral perfusion pressure, potentially leading to cerebral tissue ischemia and edema. Additionally, the reduction of cerebral small veins may facilitate the infiltration of inflammatory factors into the brain parenchyma, thereby eliciting neuroinflammatory responses. Susceptibility-weighted imaging (SWI) is a valuable modality for the efficient assessment of cerebral small veins, precisely the deep medullary vein (DMV), and holds promise for the identification of precise and reliable imaging biomarkers for AD. This review presents a comprehensive overview of the current advancements and obstacles to the impairment of cerebral small veins in AD. Additionally, we emphasize future research avenues and the importance of conducting further investigations in this domain.

Association of ADAMTS13 activity with cerebral deep medullary vein: A community-based cross-sectional study

Objectives

This study aims to investigate whether circulating ADAMTS13 activity can offer insights into the mechanism of pathophysiological changes in deep medullary veins (DMVs).

Methods

This study was conducted on a community cohort of elderly individuals in Shanghai. Plasma von Willebrand factor (VWF) levels and ADAMTS13 activity were measured. A validated DMV score described the overall burden of DMV on the brain. Through ordinal regression models, we investigated the correlation between VWF levels, ADAMTS13 activity, and increasing severity of DMV score while adjusting for demographics and cardiovascular risk factors.

Results

The study enrolled 262 subjects according to the inclusion criteria. The mean VWF level (1.35 ± 0.25) was higher in the DMV group than in the group without DMV (1.25 ± 0.30) (p = 0.025), and ADAMTS13 activity (83.76 ± 7.96) was relatively lower. After adjusting for age, sex, alcohol consumption, smoking, hypertension, and diabetes, reduced ADAMTS13 activity [β = -7.78; 95 % CI (-10.21, -5.35) p < 0.01] was associated with DMV. Moreover, correlation analysis indicated that ADAMTS13 activity was negatively correlated with the DMV score (Kendall's tau-b = -0.53, p < 0.001).

Discussion

In summary, there was an inverse correlation observed between ADAMTS13 activity and the DMV score, which may provide some clinical clues for exploring the potential pathogenesis of DMV.

Discontinuity of deep medullary veins in SWI is associated with deep white matter hyperintensity volume and cognitive impairment in cerebral small vessel disease

BACKGROUND

Discontinuation of the deep medullary veins (DMVs) may be an early imaging marker for identifying cognitive impairment caused by cerebral small vessel disease (CSVD). However, this method lacks mechanistic exploration. We aimed to investigate whether the DMV score is related to CSVD imaging markers and cognitive impairment in patients with CSVD.

METHODS

This retrospective study included patients with CSVD who completed DMV score and cognition (e.g., MMSE, MoCA) assessments, and underwent MRI scanning (T2-FLAIR for white matter hyperintensities (WMH) volume, T1-weighted MRI for brain parenchymal fractions (BPF) analysis, and SWI for assessment of DMV score). The CSVD imaging markers were quantitatively assessed using the AccuBrain® system. We assessed the diagnostic value of neuroimaging biomarkers for detecting CSVD-related cognitive impairment. In addition, we explored the relationship between the DMV score, CSVD imaging markers, and cognition using mediation analysis.

RESULTS

Ninety-four patients with CSVD were divided into a cognitive impairment group (n = 39) and a non-cognitive impairment group (n = 55). Higher DMV scores, larger WMH volumes, and smaller BPF were observed in the cognitive impairment group than those in the non-cognitive impairment group. Receiver operating characteristics (ROC) analysis revealed that the discovery value of the integration of patient age, BPF, whole WMH volume, and DMV score for cognitive impairment was 0.742, with a sensitivity and specificity of 79.5 % and 61.5 %, respectively. Mediation analysis showed mediation by WMH and BPF in the relationship between DMV score and cognitive impairment (all P < 0.05).

LIMITATIONS

This study did not evaluate the DMV score in subregions according to DMV anatomy.

CONCLUSIONS

The DMV score is significantly associated with cognitive impairment in patients with CSVD, and this association is mediated through WMH and BPF.

Deep medullary vein damage correlates with small vessel disease in small vessel occlusion acute ischemic stroke

OBJECTIVES

We aim to investigate whether cerebral small vessel disease (cSVD) imaging markers correlate with deep medullary vein (DMV) damage in small vessel occlusion acute ischemic stroke (SVO-AIS) patients.

METHODS

The DMV was divided into six segments according to the regional anatomy. The total DMV score (0-18) was calculated based on segmental continuity and visibility. The damage of DMV was grouped according to the quartiles of the total DMV score. Neuroimaging biomarkers of cSVD including white matter hyperintensity (WMH), cerebral microbleed (CMB), perivascular space (PVS), and lacune were identified. The cSVD score were further analyzed.

RESULTS

We included 229 SVO-AIS patients, the mean age was 63.7 ± 23.1 years, the median NIHSS score was 3 (IQR, 2-6). In the severe DMV burden group (the 4th quartile), the NIHSS score grade (6 (3-9)) was significantly higher than other groups (p < 0.01). The grade scores for basal ganglia PVS (BG-PVS) were positively correlated with the degree of DMV (R = 0.67, p < 0.01), rather than centrum semivole PVS (CS-PVS) (R = 0.17, p = 0.1). In multivariate analysis, high CMB burden (adjusted odds ratio [aOR], 25.38; 95% confidence interval [CI], 1.87-345.23) was associated with severe DMV scores. In addition, BG-PVS was related to severe DMV burden in a dose-dependent manner: when BG-PVS score was 3 and 4, the aORs of severe DMV burden were 18.5 and 12.19, respectively.

CONCLUSION

The DMV impairment was associated with the severity of cSVD, which suggests that DMV burden may be used for risk stratification in SVO-AIS patients.

CLINICAL RELEVANCE STATEMENT

The DMV damage score, based on the association between small vessel disease and the deep medullary veins impairment, is a potential new imaging biomarker for the prognosis of small vessel occlusion acute ischemic stroke, with clinical management implications.

KEY POINTS

• The damage to the deep medullary vein may be one mechanism of cerebral small vessel disease. • Severe burden of the basal ganglia perivascular space and cerebral microbleed is closely associated with significant impairment to the deep medullary vein. • The deep medullary vein damage score may reflect a risk of added vascular damage in small vessel occlusion acute ischemic stroke patients.

BOLD cardiorespiratory pulsatility in the brain: from noise to signal of interest

Functional magnetic resonance imaging (fMRI) based on the Blood Oxygen Level Dependent (BOLD) contrast has been extensively used to map brain activity and connectivity in health and disease. Standard fMRI preprocessing includes different steps to remove confounds unrelated to neuronal activity. First, this narrative review explores how signal fluctuations due to cardiac and respiratory activity, usually considered as "physiological noise" and regressed out from fMRI time series. However, these signal components bear useful information about some mechanisms of brain functioning (e.g., glymphatic clearance) or cerebrovascular compliance in response to arterial pressure waves. Aging and chronic diseases can cause stiffening of the aorta and other main arteries, with a reduced dampening effect resulting in greater transmission of pressure impulses to the brain. Importantly, the continuous hammering of cardiac pulsations can produce local alterations of the mechanical properties of the small cerebral vessels, with a progressive deterioration that ultimately affects neuronal functionality. Second, the review emphasizes how fMRI can study the brain patterns most affected by cardiac pulsations in health and disease with high spatiotemporal resolution, offering the opportunity to identify much more specific risk markers than systemic factors based on measurements of the vascular compliance of large arteries or other global risk factors. In this regard, modern fast fMRI acquisition techniques allow a better characterization of these pulsatile signal components due to reduced aliasing effects, turning what has been traditionally considered as noise in a signal of interest that can be used to develop novel non-invasive biomarkers in different clinical contexts.

Multiple Hypointense Vessels are Associated with Cognitive Impairment in Patients with Single Subcortical Infarction

We aimed to explore the relationship between multiple hypointense vessels and cognitive function in patients with single subcortical infarction (SSI) and the role of SSI with different etiological mechanisms in the above relationship. Multiple hypointense vessels were measured by the number of deep medullary veins (DMVs), DMVs score, and cortical veins (CVs) score. The Montreal Cognitive Assessment (MoCA), the Shape Trail Test (STT), and the Stroop Color and Word Test (SCWT) were assessed to evaluate cognitive function. SSI was dichotomized as branch atheromatous disease (BAD) and cerebral small vessel disease (CSVD)-related SSI by whole-brain vessel-wall magnetic resonance imaging. We included a total of 103 acute SSI patients. After adjustments were made for related risk factors of cognitive function, the SSI patients with higher DMVs score were more likely to have longer STT-B (P = 0.001) and smaller STT-B-1 min (P = 0.014), and the SSI patients with higher CVs score were more likely to have shorter STT-A (P = 0.049). In subgroup analysis, we found that the negative relationship between DMVs scores and cognitive function and the positive relationship between CVs scores and cognitive function were significantly stronger in BAD patients. We provided valuable insights into the associations between DMVs, CVs, and multi-domain cognitive impairment in SSI patients, which underscored the necessity to further study the dynamic alterations of venules and their specific influence on post-stroke cognitive impairment.

Cerebral venous congestion alters brain metabolite profiles, impairing cognitive function

Vascular cognitive impairment (VCI) represents the second most common cause of dementia after Alzheimer's disease, and pathological changes in cerebral vascular structure and function are pivotal causes of VCI. Cognitive impairment caused by arterial ischemia has been extensively studied the whole time; the influence of cerebral venous congestion on cognitive impairment draws doctors' attention in recent clinical practice, but the underlying neuropathophysiological alterations are not completely understood. This study elucidated the specific pathogenetic role of cerebral venous congestion in cognitive-behavioral deterioration and possible electrophysiological mechanisms. Using cerebral venous congestion rat models, we found these rats exhibited decreased long-term potentiation (LTP) in the hippocampal dentate gyrus and impaired spatial learning and memory. Based on untargeted metabolomics, N-acetyl-L-cysteine (NAC) deficiency was detected in cerebral venous congestion rats; supplementation with NAC appeared to ameliorate synaptic deficits, rescue impaired LTP, and mitigate cognitive impairment. In a cohort of cerebral venous congestion patients, NAC levels were decreased; NAC concentration was negatively correlated with subjective cognitive decline (SCD) score but positively correlated with mini-mental state examination (MMSE) score. These findings provide a new perspective on cognitive impairment and support further exploration of NAC as a therapeutic target for the prevention and treatment of VCI.

The Venular Side of Cerebral Amyloid Angiopathy: Proof of Concept of a Neglected Issue

Small vessel diseases (SVD) is an umbrella term including several entities affecting small arteries, arterioles, capillaries, and venules in the brain. One of the most relevant and prevalent SVDs is cerebral amyloid angiopathy (CAA), whose pathological hallmark is the deposition of amyloid fragments in the walls of small cortical and leptomeningeal vessels. CAA frequently coexists with Alzheimer's Disease (AD), and both are associated with cerebrovascular events, cognitive impairment, and dementia. CAA and AD share pathophysiological, histopathological and neuroimaging issues. The venular involvement in both diseases has been neglected, although both animal models and human histopathological studies found a deposition of amyloid beta in cortical venules. This review aimed to summarize the available information about venular involvement in CAA, starting from the biological level with the putative pathomechanisms of cerebral damage, passing through the definition of the peculiar angioarchitecture of the human cortex with the functional organization and consequences of cortical arteriolar and venular occlusion, and ending to the hypothesized links between cortical venular involvement and the main neuroimaging markers of the disease.

Extracellular Vesicles Play a Central Role in Cerebral Venous Disease-Associated Brain Atrophy

Cerebral venous abnormalities, distinct from traditional arterial diseases, have been linked to brain atrophy in a previous community-based cohort study, specifically in relation to the reduction of deep medullary veins (r-DMVs). To better understand the properties and biological functions of serum extracellular vesicles (EVs) in cerebral venous disease-associated brain atrophy, EVs are extracted from the serum of both participants with r-DMV and normal controls and analyzed their proteomic profiles using Tandem Mass Tag label quantitation analysis. Phenotypic experiments showed that EVs from individuals with r-DMVs are able to disrupt the normal functions of neurons, endothelial cells, and smooth muscle cells, and induce A1 reactive astrocytes. Additionally, this study provided a comprehensive characterization of the proteomic profile of DMV EVs and found that the collagen hydroxyproline is upregulated, while complement C3 is downregulated in the r-DMV group, suggesting that r-DMV may not be a simple pathological phenomenon and highlighting the potential involvement of EVs in the progression of brain atrophy in r-DMVs which has implications for the development of future therapeutic strategies.

Arteriolosclerosis differs from venular collagenosis in relation to cerebrovascular parenchymal damages: an autopsy-based study

BACKGROUND AND PURPOSE

Cerebrovascular parenchymal damage is prevalent in ageing brains; however, its vascular aetiology has not been fully elucidated. In addition to the underlying role of sclerotic arterioles, the correlation between collagenised venules has not been clarified. Here, we aimed to investigate the associations between microvascular injuries, including arteriolosclerosis and venular collagenosis, and related parenchymal damages in ageing brains, to investigate the underlying correlations.

METHODS

We evaluated arteriolosclerosis and venular collagenosis in 7 regions from 27 autopsy cases with no history of stroke or brain tumour. The correlations between the ratio of arteriolosclerosis, venular collagenosis and the severity of cerebrovascular parenchymal damage, including lacunes, microinfarcts, myelin loss, and parenchymal and perivascular haemosiderin deposits, were assessed.

RESULTS

Arteriolosclerosis and venular collagenosis became more evident with age. Arteriolosclerosis was associated with lacunes (p=0.004) and brain parenchymal haemosiderin deposits in the superior frontal cortex (p=0.024) but not with leukoaraiosis severity. Venular collagenosis was not associated with the number of lacunes or haemosiderin, while white matter generally became paler with severe venular collagenosis in the periventricular (β=-0.430, p=0.028) and deep white matter (β=-0.437, p=0.025).

CONCLUSION

Our findings imply an important role for venular lesions in relation to microvessel-related parenchymal damage which is different from that for arteriolosclerosis. Different underlying mechanisms of both cerebral arterioles and venules require further investigation.

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.

Examining temporal features of BOLD-based cerebrovascular reactivity in clinical populations

Background

Conventional cerebrovascular reactivity (CVR) estimation has demonstrated that many brain diseases and/or conditions are associated with altered CVR. Despite the clinical potential of CVR, characterization of temporal features of a CVR challenge remains uncommon. This work is motivated by the need to develop CVR parameters that characterize individual temporal features of a CVR challenge.

Methods

Data were collected from 54 adults and recruited based on these criteria: (1) Alzheimer's disease diagnosis or subcortical Vascular Cognitive Impairment, (2) sleep apnea, and (3) subjective cognitive impairment concerns. We investigated signal changes in blood oxygenation level dependent (BOLD) contrast images with respect to hypercapnic and normocapnic CVR transition periods during a gas manipulation paradigm. We developed a model-free, non-parametric CVR metric after considering a range of responses through simulations to characterize BOLD signal changes that occur when transitioning from normocapnia to hypercapnia. The non-parametric CVR measure was used to examine regional differences across the insula, hippocampus, thalamus, and centrum semiovale. We also examined the BOLD signal transition from hypercapnia back to normocapnia.

Results

We found a linear association between isolated temporal features of successive CO₂ challenges. Our study concluded that the transition rate from hypercapnia to normocapnia was significantly associated with the second CVR response across all regions of interest (p < 0.001), and this association was highest in the hippocampus (R² = 0.57, p < 0.0125).

Conclusion

This study demonstrates that it is feasible to examine individual responses associated with normocapnic and hypercapnic transition periods of a BOLD-based CVR experiment. Studying these features can provide insight on between-subject differences in CVR.

Associations of deep medullary veins with vascular risk factors, laboratory indicators, and cerebral small vessel disease: A population-based study

OBJECTIVE

Deep medullary veins (DMVs) were not considered a typical marker of cerebral small vessel disease (CSVD) due to limited understanding of their involvement in pathology of CSVD. This study aimsto investigate potential vascular risk factors for DMVs and their associations with CSVD.

METHODS

In total, 1909 community-dwelling participants were included in this analysis. Demographic, clinical, laboratory, and imaging data were collected. DMV scores (0-18) werecalculated as the sum of bilateral frontal, parietal, and occipital regional scores using a semiquantitative visual scale (0-3). The presence, total burden, and imaging markers of CSVD were assessed. Linear regression analyses were conducted to explore potential vascular factors for DMV scores. Binary and ordinal logistic regression analyses were performed to investigate the associations of DMV scores with CSVD and its markers.

RESULTS

Mean age was 61.8 (SD 6.5) years, and 1027 (53.8%) of participants were men. The median DMV scores were14 (IQR 12-16). DMV scores wererelated to age, male sex, body mass index, diastolic blood pressure, hypercholesterolaemia, atrial fibrillation, current drinking, total cholesterol, triglycerides, low-density lipoprotein, hemoglobin A1c, leukocytes, lymphocytes, hemoglobin, and platelets (p < .05). DMV scores wereassociated with the presence and total burden of CSVD (Rothwell's scale), modified white matter hyperintensity burden, and enlarged perivascular spaces in centrum semiovale (p < .05). However, these associations between DMV scores and CSVD disappeared after adjusting for potential confounders.

CONCLUSION

Several conventional vascular factors were associated with DMVs. The relationship between DMVs and CSVD was vulnerable, suggesting decreased visible and discontinuous DMVs may differ mechanistically from traditional markers of CSVD.

Effect of dynamic cerebral autoregulation on the association between deep medullary vein changes and cerebral small vessel disease

Changes in the deep medullary vein (DMV) are reported to be associated with cerebral small vessel disease (CSVD). While the mechanisms of this association are unclear, dynamic cerebral autoregulation (dCA) has been speculated to participate in this association. Thus, we aimed to verify the association between DMV changes and total CSVD burden and further investigate the effect of dCA function on this correlation. In this prospective study, 95 Asian patients aged ≥18 years were included in the final assessment. DMV scores and total CSVD burden were determined using magnetic resonance imaging sequences. Transfer function analysis was performed to analyze dCA function. Generalized linear regressions were used to assess the relationship between DMV changes and total CSVD burden as well as between DMV changes and dCA function. An interaction model was utilized to assess the effect of dCA function on the association between DMV changes and total CSVD burden. Generalized linear models showed a significant positive association between DMV changes and total CSVD burden (p = 0.039) and a significant negative association between DMV changes and dCA function (p = 0.018). The interaction model demonstrated a significant positive interaction of dCA impairment on the association between DMV changes and the total CSVD burden (p = 0.02). Thus, we came to the conclusion that changes in DMV were correlated independently with both CSVD and dCA impairment and furthermore, impaired dCA function play an interaction effect on the association between DMV changes and the total CSVD burden. Our results can help improve the understanding of the complex pathogenesis and progression of CSVD, thereby facilitating early intervention and treatment development.

Dietary nitrate biochemistry and physiology. An update on clinical benefits and mechanisms of action

It is now more than 35 years since endothelium derived relaxing factor was identified as nitric oxide (NO). The last few decades have seen an explosion around nitric oxide biochemistry, physiology and clinical translation. The science reveals that all chronic disease is associated with decreased blood flow to the affected organ which results in increased inflammation, oxidative stress and immune dysfunction. This is true for cardiovascular disease, neurological disease, kidney, lung, liver disorders and every other major disorder. Since nitric oxide controls and regulates blood flow, oxygen and nutrient delivery to every cell, tissue and organ in the body and also mitigates inflammation, oxidative stress and immune dysfunction, a focus on restoring nitric oxide production is an obvious therapeutic strategy for a number of poorly managed chronic diseases. Since dietary nitrate is a major contributor to endogenous nitric oxide production, it should be considered as a means of therapy and restoration of nitric oxide. This review will update on the current state of the science and effects of inorganic nitrate administered through the diet on several chronic conditions and reveal how much is needed. It is clear now that antiseptic mouthwash and use of antacids disrupt nitrate metabolism to nitric oxide leading to clinical symptoms of nitric oxide deficiency. Based on the science, nitrate should be considered an indispensable nutrient that should be accounted for in dietary guidelines.

Whether jugular venous reflux relates to more serious ischemic white matter lesions?

OBJECTIVE

To evaluate whether jugular venous reflux (JVR) relates to more serious ischemic white matter lesions (WMLs).

PATIENTS AND METHODS

Fifty cases were enrolled and divided into absent to mild ischemic WMLs group and moderate to severe ischemic WMLs group. Then the univariate and multivariate analyses were conducted to evaluate the relationship between JVR and moderate to severe ischemic WMLs, and a receiver operating characteristic (ROC) curve was used to evaluate the predictive value of JVR for moderate to severe ischemic WMLs.

RESULTS

There were 28 patients in the absent to mild ischemic WMLs group and 22 patients in the moderate to severe ischemic WMLs group. There was no significant difference between the two groups in gender, blood lipid indexes, proportions of diabetes, and abnormal deep cerebral veins (all p > 0.05). However, compared with the absent to mild ischemic WMLs group, the moderate to severe ischemic WMLs group was older and had a higher proportion of hypertension and JVR (p = 0.005; p < 0.001; p < 0.001, respectively). Multivariate logistic regression analysis showed that JVR was an independent risk factor for moderate to severe ischemic WMLs (OR = 17.679, 95 % CI: 3.056-102.286, p = 0.001). Furthermore, the area under curve of JVR combined with hypertension was 0.912 (p < 0.001), and the specificity of predicting moderate to severe ischemic WMLs was 92.9 %.

CONCLUSION

Our study suggested that JVR might relate to more severe ischemic WMLs.

Spontaneous Echo Contrast in the Left Atrium and Aortic-Arch Atheroma, Detected by Transesophageal Echocardiography, Was Negatively Correlated with Cognitive Function

BACKGROUND

The relationship between transesophageal echocardiography findings and cognitive function.

OBJECTIVE

This study aimed to establish an association between transesophageal echocardiography findings and cognitive function in stroke survivors.

METHODS

A single-center study was conducted between April 1, 2017 and March 31, 2022. All subjects that were included had a past history of ischemic stroke and were admitted after >21 days from onset. The participants underwent cognitive function tests including a Mini-Mental State Examination, Revised Hasegawa Dementia Scale, Frontal Assessment Battery, and transesophageal echocardiography.

RESULTS

The results of 126 participants were analyzed. The cognitive function of participants with a spontaneous echo contrast (+) in the left atrium including appendage or of those with an aorta-arch plaque with a maximum thickness ≥4 mm significantly worse while neither the patent foramen ovale nor the branch extending plaque influenced cognitive function (The median cognitive scores of the spontaneous echo contrast (-) versus (+) were 26 versus 22, p < 0.01**, 26 versus 21, p < 0.001***, and 14 versus 11, p < 0.01**. Those of the aortic-arch plaque max thickness (<4 mm) versus (≥4 mm) were 26 versus 25, p < 0.05*, 27 versus 24, p < 0.05*, and 15 versus 13, p < 0.05*).

CONCLUSION

Our findings show that spontaneous echo contrast in the left atrium and aortic-arch atheroma detected by transesophageal echocardiography, were negatively associated with cognitive function.

Deep medullary veins: a promising neuroimaging marker for mild cognitive impairment in outpatients

BACKGROUND AND PURPOSE

Mild cognitive impairment is an age-dependent pre-dementia state caused by varied reasons. Early detection of MCI helps handle dementia. Vascular factors are vital for the occurrence of MCI. This study investigates the correlation between deep medullary veins and multi-dimensional cognitive outcomes.

MATERIALS AND METHODS

A total of 73 participants with MCI and 32 controls were enrolled. Minimum Mental State Examination and Montreal Cognitive Assessment were used to examine the global cognitive function, and different cognitive domains were measured by specific neuropsychological tests. MRI was used to assess the visibility of the DMV and other neuroimage markers.

RESULTS

DMV score was statistically significantly higher in the MCI group compared with the control group (P = 0.009) and independently related to MCI (P = 0.007). Linear regression analysis verified that DMV score was linearly related to global cognition, memory, attention, and executive function after adjusting for cerebrovascular risk factors.

CONCLUSION

DMV score was independently related to the onset of MCI, and correlates with overall cognition, memory, attention, and executive function in outpatients.

Venous Collagenosis as Pathogenesis of White Matter Hyperintensity

OBJECTIVE

Periventricular white matter hyperintensities (pvWMHs) are commonly observed on MRI in older individuals and are associated with cognitive and motor decline. The etiology of pvWMH remains unknown. Venous collagenosis has been implicated, which may also interfere with perivascular fluid flow leading to dilation of perivascular spaces (PVS). Here, we examine relationships between in vivo pvWMH volume and ex vivo morphological quantification of collagenosis and the PVS in veins and arteries.

METHODS

Brain tissue from 25 Oregon Alzheimer's Disease Research Center subjects was selected to cover the full range of WMH burden. Tissue from white matter abutting the ventricle was stained with Masson's trichrome and smooth muscle actin. An automated hue based algorithm identified and segmented vessel into collagenized vessel walls, lumen, and PVS. Multiple linear regressions with pvWMH volume as the dependent variable and either collagen thickness or PVS width were performed with covariates of vessel diameter, age at death, sex, and interval between MRI and death.

RESULTS

PVS width and collagen thickness were significantly correlated in both arteries (r = 0.21, p = 0.001) and veins (r = 0.23, p = 0.001). Increased venous collagen (p = 0.017) was a significant predictor of higher pvWMH burden while arterial collagen was not (p = 0.128). Neither PVS width in arteries (p = 0.937) nor veins (p = 0.133) predicted pvWMH burden.

INTERPRETATION

These findings are consistent with a model in which venous collagenosis mediates the relationship between vascular risk factors and pvWMH. This study confirms the importance of changes to the venous system in contributing to MRI white matter lesions commonly observed with advanced age. ANN NEUROL 2022;92:992-1000.

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.

Brain Deep Medullary Veins on 7T MRI in Dutch-Type Hereditary Cerebral Amyloid Angiopathy

Background: Deep medullary vein (DMV) changes occur in cerebral small vessel diseases (SVD) and in Alzheimer’s disease. Cerebral amyloid angiopathy (CAA) is a common SVD that has a high co-morbidity with Alzheimer’s disease. So far, DMVs have not been evaluated in CAA. Objective: To evaluate DMVs in Dutch-type hereditary CAA (D-CAA) mutation carriers and controls, in relation to MRI markers associated with D-CAA. Methods: Quantitative DMV parameters length, tortuosity, inhomogeneity, and density were quantified on 7 Tesla 3D susceptibility weighted MRI in pre-symptomatic D-CAA mutation carriers (n = 8), symptomatic D-CAA mutation carriers (n = 8), and controls (n = 25). Hemorrhagic MRI markers (cerebral microbleeds, intracerebral hemorrhages, cortical superficial siderosis, convexity subarachnoid hemorrhage), non-hemorrhagic MRI markers (white matter hyperintensities, enlarged perivascular spaces, lacunar infarcts, cortical microinfarcts), cortical grey matter perfusion, and diffusion tensor imaging parameters were assessed in D-CAA mutation carriers. Univariate general linear analysis was used to determine associations between DMV parameters and MRI markers. Results: Quantitative DMV parameters length, tortuosity, inhomogeneity, and density did not differ between pre-symptomatic D-CAA mutation carriers, symptomatic D-CAA mutation carriers, and controls. No associations were found between DMV parameters and MRI markers associated with D-CAA. Conclusion: This study indicates that vascular amyloid-β deposition does not affect DMV parameters. In patients with CAA, DMVs do not seem to play a role in the pathogenesis of MRI markers associated with CAA.

Reduced white matter venous density on MRI is associated with neurodegeneration and cognitive impairment in the elderly

High-resolution susceptibility weighted imaging (SWI) provides unique contrast to small venous vasculature. The conspicuity of these mesoscopic veins, such as deep medullary veins in white matter, is subject to change from SWI venography when venous oxygenation in these veins is altered due to oxygenated blood susceptibility changes. The changes of visualization in small veins shows potential to depict regional changes of oxygen utilization and/or vascular density changes in the aging brain. The goal of this study was to use WM venous density to quantify small vein visibility in WM and investigate its relationship with neurodegenerative features, white matter hyperintensities (WMHs), and cognitive/functional status in elderly subjects (N = 137). WM venous density was significantly associated with neurodegeneration characterized by brain atrophy (β = 0.046± 0.01, p < 0.001), but no significant association was found between WM venous density and WMHs lesion load (p = 0.3963). Further analysis of clinical features revealed a negative trend of WM venous density with the sum-of-boxes of Clinical Dementia Rating and a significant association with category fluency (1-min animal naming). These results suggest that WM venous density on SWI can be used as a sensitive marker to characterize cerebral oxygen metabolism and different stages of cognitive and functional status in neurodegenerative diseases.

Pathogenesis and research progress in leukoaraiosis

Leukoaraiosis is a common imaging marker of cerebral small vessel disease. In recent years, with the continuous advances in brain imaging technology, the detection rate of leukoaraiosis is higher and its clinical subtypes are gradually gaining attention. Although leukoaraiosis has long been considered an incidental finding with no therapeutic necessity, there is now growing evidence linking it to, among other things, cognitive impairment and a high risk of death after stroke. Due to different research methods, some of the findings are inconsistent and even contradictory. Therefore, a comprehensive and in-depth study of risk factors for leukoaraiosis is of great clinical significance. In this review, we summarize the literature on leukoaraiosis in recent years with the aim of elucidating the disease in terms of various aspects (including pathogenesis, imaging features, and clinical features, etc.).

Different mechanisms in periventricular and deep white matter hyperintensities in old subjects

Objective

Although multiple pieces of evidence have suggested that there are different mechanisms in periventricular white matter hyperintensities (PWMHs) and deep white matter hyperintensities (DWMHs), the exact mechanism remains uncertain.

Methods

We reviewed clinical and imaging data of old participants from a local She Ethnic group. We assessed the cerebral blood flow of white matter (WM-CBF) on arterial spin-labeling, deep medullary veins (DMVs) visual score on susceptibility-weighted imaging, and index for diffusion tensor image analysis along the perivascular space (ALPS index), indicating glymphatic function on diffusion tensor imaging. Furthermore, we investigated their relationships with volumes of PWMHs and DWMHs.

Results

A total of 152 subjects were included, with an average age of 63 ± 8 years old. We found that higher age and history of hypertension were independently related to higher volumes of both PWMHs and DWMHs (all p &lt; 0.05). Lower ALPS index was independently associated with higher PWMHs volumes (β = 0.305, p &lt; 0.001), and this relationship was accounted for by the indirect pathway via DMVs score (β = 0.176, p = 0.017). Both lower ALPS index and WM-CBF were independent risk factors for higher DWMHs volumes (β = −0.146, p = 0.041; β = −0.147, p = 0.036).

Conclusions

Our study indicated that there were different mechanisms in PWMHs and DWMHs. PWMHs were mainly attributed to the damage of veins due to the dysfunction of the glymphatic pathway, while DWMHs could be affected by both ischemia-hypoperfusion and dysfunction of the glymphatic pathway.

Advances in knowledge

The relationship between glymphatic dysfunction and PWMHs might be accounted for by the indirect pathway via venous abnormalities, a glymphatic dysfunction, and lower CBF in white matter were independent risk factors for DWMHs.

[Morphological characteristics of the brain nervous tissue during aging]

OBJECTIVE

Identification of morphological manifestations and evaluation of morphometric parameters of the nervous tissue in various structures of the human brain during aging.

MATERIAL AND METHODS

Autopsy material was obtained from patients whose causes of death were not associated with neurological diseases. Three age groups were studied: young (35-45 years old) (n=10); eldery (75-89 years old) (n=20); centenarians (over 90 years old) (n=10). Quantitative analysis of large neurons in the compact part of the substantia nigra, basal ganglia, layer V of the cortex, and the pyramidal layer of the hippocampus was carried out. In addition, the brain mass, the thickness of the cortex of the precentral gyrus were measured, the glial index was calculated, and the morphological signs of age-related involution of the brain tissue and intracerebral vessels were assessed.

RESULTS

In senile and centenarians, compared with young people, there was a progressive reduction in large neurons of layer V of the cortex, basal ganglia, the pyramidal layer of the hippocampus and substantia nigra, a decrease in brain mass and thickness of the cortex of the precentral gyrus, as well as an increase in the glial index. Changes in blood vessels characteristic of aging are described. Also, during aging, signs characteristic of neurodegeneration were found.

CONCLUSION

The results of the study confirm that such brain structures as the cortex of the precentral gyrus, the hippocampus, the basal ganglia, and the substantia nigra lose large neurons with age, followed by the development of gliosis. The identified morphological changes characteristic of aging are phenomenologically similar to a certain set of morphological changes in neurodegenerative diseases of late age.

Nonalcoholic Fatty Liver Disease and Altered Neuropsychological Functions in Patients with Subcortical Vascular Dementia

NAFLD is the most common cause of abnormality in liver function tests. NAFLD is considered a potential cardiovascular risk factor and is linked to cardiovascular risk factors such as obesity, hypertension, type 2 diabetes, and dyslipidemia. Few previous studies have investigated whether NAFLD could be independently associated with cognitive impairment. The current study aims to find a possible role of NAFLD in the development of subcortical vascular dementia (sVaD). We considered NAFLD as a possible independent vascular risk factor or, considering its metabolic role, associated with other commonly accepted sVaD risk factors, i.e., lack of folate, vitamin B12, and vitamin D-OH25, and increased levels of homocysteine. We studied 319 patients diagnosed with sVaD. All patients underwent an abdominal ultrasound examination to classify steatosis into four levels (1-none up to 4-severe). sVaD patients were divided into two groups according to the presence or absence of NAFLD. Our results demonstrated a strong correlation between NAFLD and sVaD. Patients with the two comorbidities had worse neuropsychological outcomes and a worse metabolic profile. We also found a robust relationship between NAFLD and severe vitamin B12, folate, vitamin D hypovitaminosis, and higher hyperhomocysteinemia levels. This way, it is evident that NAFLD contributes to a more severe metabolic pathway. However, the strong relationship with the three parameters (B12, folate and vitamin D, and homocysteinemia) suggests that NAFLD can contribute to a proinflammatory condition.

Age related increase in internal jugular vein size parallels temporal development of periventricular white matter hyperintensities

INTRODUCTION

Age-related white matter hyperintensities are associated with cognitive impairment and dementia. Venous insufficiency has recently been proposed as a potential mechanism for the development of periventricular white matter hyperintensities based on the neuroanatomic distribution. The current study assesses age related changes of the internal jugular veins and its association with white matter hyperintensities.

METHODS

A retrospective study was performed assessing patients with CT angiography and MRI within a 4-week window. The size of the internal jugular veins, straight sinus, vein of Galen and internal cerebral veins were measured on the CT angiography. A normalized neck venous ratio was developed. Burden of white matter hyperintensities were quantified on MRI using periventricular/deep Fazekas scores. Association was assessed using correlation analysis and multrivariate linear modelling, and differences between groups were assessed using t-test, ANOVA or Kruskal-Wallis test, using p<.05 for significance.

RESULTS

One hundred eighty-two patients were included with a mean age of 65.2 +/- 16.8 (51.6% females). Age was correlated with the normalized neck venous ratio (r_s =0.25, p<.001), and, with both, the periventricular Fazekas (r_s =0.63, p<.001) and the deep Fazekas (r_s =0.57, p<.001) grades. The periventricular Fazekas score was positively correlated with the normalized neck venous ratio (r_s =0.21, p=.003), but not significant on multivariate analysis accounting for age.

CONCLUSION

The internal jugular veins demonstrate age related increase in size, paralleling the progression of periventricular white matter hyperintensities. Age remains the strongest predictor of white matter hyperintensities. Further work is needed to evaluate any causal role of venous changes on white matter hyperintensities. This article is protected by copyright. All rights reserved.

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.

Deep medullary veins are associated with widespread brain structural abnormalities

Our aim is to investigate the association of cerebral deep medullary veins (DMVs) with white matter microstructural integrity and regional brain atrophy in MRI. In a community-based cohort of 979 participants (mean age 55.4 years), DMVs were identified on susceptibility-weighted imaging. Brain structural measurements including gray matter and hippocampus volumes, as well as diffusion tensor metrics, were evaluated. The mean (SD)number of DMVs was 19.0 (1.7). A fewer number of DMVs was related to lower fractional anisotropy and higher mean diffusivity in multiple voxels on the white matter skeleton (threshold-free cluster enhancement corrected p < 0.05, adjusted for age and sex). Also, fewer DMVs were significantly related to a lower gray matter fraction and a hippocampal fraction (0.10 and 0.11 per DMV, respectively; SE, 0.03 for both; p < 0.001 for both). A significant correlation between DMVs' reduction and cortical atrophy was observed in the bilateral occipital lobes, temporal lobes, hippocampus, and frontal lobes (p < 0.001, adjusted for age, sex, and total intracranial volume). Our results provided evidence that cerebral small venules disease play a role in brain parenchymal lesions and neurodegenerative processes.

Abnormalities of Retinal Structure and Microvasculature are Associated with Cerebral White Matter Hyperintensities

PURPOSE

While retinal microvasculature represents cerebral small vessels, the retinal nerve fiber layer is the extended white matter of the brain. We aimed to investigate the correlation between changes in retina and white matter hyperintensities (WMH).

METHODS

64 candidates with WMH received the optical coherence tomography angiography (OCTA) examination. WMH were divided into mild or moderate/severe groups according to the Fazekas score. After imaging superficial capillary plexus (SCP) and deep capillary plexus (DCP), we revealed the microvascular density parameters (vascular perfusion density (VPD), vascular length density (VLD), and fovea avascular zone area (FAZ-A)) and morphological parameters (vessel diameter index (VDI), fractal dimension (FD), and vessel tortuosity (VT)). The software algorithm measured the thickness of the peripapillary retina nerve fiber layer (PRNFL).

RESULTS

32 were classified as having mild WMH and 32 were moderate/severe. The Median (interquartile range) ages of the two groups were 58 (54-64) and 61 (57-67) years, respectively. A decrease of FD, VPD and VLD in either SCP or DCP appeared with an increased risk of moderate/severe WMH. Although changes of capillary plexus were not associated with PWMH, decreased FD, VPD, VLD and FAZ-A in either SCP or DCP was associated with an increased risk of moderate/severe DWMH. Participants with moderate/severe WMH demonstrated reduced PRNFL thickness, particularly in the DWMH, compared with mild WMH.

CONCLUSIONS

Abnormalities of retinal microvascular density, morphological parameters, and PRNFL thickness are correlated with the incidence of moderate/severe WMH, particularly the DWMH, suggesting that arteriosclerosis and hypoperfusion are the causes of DWMH.

Small Vessel Disease: Ancient Description, Novel Biomarkers

Small vessel disease (SVD) is one of the most frequent pathological conditions which lead to dementia. Biochemical and neuroimaging might help correctly identify the clinical diagnosis of this relevant brain disease. The microvascular alterations which underlie SVD have common origins, similar cognitive outcomes, and common vascular risk factors. Nevertheless, the arteriolosclerosis process, which underlines SVD development, is based on different mechanisms, not all completely understood, which start from a chronic hypoperfusion state and pass through a chronic brain inflammatory condition, inducing a significant endothelium activation and a consequent tissue remodeling action. In a recent review, we focused on the pathophysiology of SVD, which is complex, involving genetic conditions and different co-morbidities (i.e., diabetes, chronic hypoxia condition, and obesity). Currently, many points still remain unclear and discordant. In this paper, we wanted to focus on new biomarkers, which can be the expression of the endothelial dysfunction, or of the oxidative damage, which could be employed as markers of disease progression or for future targets of therapies. Therefore, we described the altered response to the endothelium-derived nitric oxide-vasodilators (ENOV), prostacyclin, C-reactive proteins, and endothelium-derived hyperpolarizing factors (EDHF). At the same time, due to the concomitant endothelial activation and chronic neuroinflammatory status, we described hypoxia-endothelial-related markers, such as HIF 1 alpha, VEGFR2, and neuroglobin, and MMPs. We also described blood–brain barrier disruption biomarkers and imaging techniques, which can also describe perivascular spaces enlargement and dysfunction. More studies should be necessary, in order to implement these results and give them a clinical benefit.

Inflammatory biomarkers and cerebral small vessel disease: a community-based cohort study

Background and purpose

Although inflammation has been proposed to be a candidate risk factor for cerebral small vessel disease (CSVD), previous findings remain largely inconclusive and vary according to disease status and study designs. The present study aimed to investigate possible associations between inflammatory biomarkers and MRI markers of CSVD.

Methods

A group of 15 serum inflammatory biomarkers representing a variety of those putatively involved in the inflammatory cascade was grouped and assessed in a cross-sectional study involving 960 stroke-free subjects. The biomarker panel was grouped as follows: systemic inflammation (high-sensitivity C reactive protein (hsCRP), interleukin 6 and tumour necrosis factor α), endothelial-related inflammation (E-selectin, P-selectin, intercellular adhesion molecule 1, vascular cell adhesion molecule 1 (VCAM-1), CD40 ligand, lipoprotein-associated phospholipase A2, chitinase-3-like-1 protein and total homocysteine (tHCY)) and media-related inflammation (matrix metalloproteinases 2, 3 and 9, and osteopontin). The association(s) between different inflammatory groups and white matter hyperintensity (WMH), lacunes, cerebral microbleeds (CMBs), enlarged perivascular space (PVS) and the number of deep medullary veins (DMVs) were investigated.

Results

High levels of serum endothelial-related inflammatory biomarkers were associated with both increased WMH volume (R²=0.435, p=0.015) and the presence of lacunes (R²=0.254, p=0.027). Backward stepwise elimination of individual inflammatory biomarkers for endothelial-related biomarkers revealed that VCAM-1 was significant for WMH (β=0.063, p=0.005) and tHCY was significant for lacunes (β=0.069, p<0.001). There was no association between any group of inflammatory biomarkers and CMBs or PVS. Systemic inflammatory biomarkers were associated with fewer DMVs (R²=0.032, p=0.006), and backward stepwise elimination of individual systemic-related inflammatory biomarkers revealed that hsCRP (β=−0.162, p=0.007) was significant.

Conclusion

WMH and lacunes were associated with endothelial-related inflammatory biomarkers, and fewer DMVs were associated with systemic inflammation, thus suggesting different underlying inflammatory processes and mechanisms.

Cerebral Vascular Dysfunctions Detected in Human Small Vessel Disease and Implications for Preclinical Studies

Cerebral small vessel disease (SVD) is highly prevalent and a common cause of ischemic and hemorrhagic stroke and dementia, yet the pathophysiology is poorly understood. Its clinical expression is highly varied, and prognostic implications are frequently overlooked in clinics; thus, treatment is currently confined to vascular risk factor management. Traditionally, SVD is considered the small vessel equivalent of large artery stroke (occlusion, rupture), but data emerging from human neuroimaging and genetic studies refute this, instead showing microvessel endothelial dysfunction impacting on cell-cell interactions and leading to brain damage. These dysfunctions reflect defects that appear to be inherited and secondary to environmental exposures, including vascular risk factors. Interrogation in preclinical models shows consistent and converging molecular and cellular interactions across the endothelial-glial-neural unit that increasingly explain the human macroscopic observations and identify common patterns of pathology despite different triggers. Importantly, these insights may offer new targets for therapeutic intervention focused on restoring endothelial-glial physiology.

The pericyte: A critical cell in the pathogenesis of CADASIL

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CADASIL is the most common hereditary small vessel disease presenting with strokes and subcortical vascular dementia caused by mutations in the NOTCH3 gene.

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CADASIL is a vasculopathy primarily involving vascular smooth-muscle cells.

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Arteriolar and capillary pericyte damage or deficiency is a key feature in disease pathogenesis.

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Pericyte-mediated cerebral venous insufficiency may explain white matter lesions and increased perivascular spaces.

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Central role of the pericyte offers novel approaches to the treatment of CADASIL.

Cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) is a hereditary small vessel disease presenting with migraine, mood and cognitive disorders, focal neurological deficits, recurrent ischemic attacks, lacunar infarcts and brain white matter changes. As they age, CADASIL patients invariably develop cognitive impairment and subcortical dementia. CADASIL is caused by missense mutations in the NOTCH3 gene resulting in a profound cerebral vasculopathy affecting primarily arterial vascular smooth muscle cells, which target the microcirculation and perfusion. Based on a thorough review of morphological lesions in arteries, veins, and capillaries in CADASIL, we surmise that arteriolar and capillary pericyte damage or deficiency appears a key feature in the pathogenesis of the disease. This may affect critical pericyte-endothelial interactions causing stroke injury and vasomotor disturbances. Changes in microvascular permeability due to perhaps localized blood-brain barrier alterations and pericyte secretory dysfunction likely contribute to delayed neuronal as well as glial cell death. Moreover, pericyte-mediated cerebral venous insufficiency may explain white matter lesions and the dilatation of Virchow-Robin perivascular spaces typical of CADASIL. The postulated central role of the pericyte offers some novel approaches to the study and treatment of CADASIL and enable elucidation of other forms of cerebral small vessel diseases and subcortical vascular dementia.

Pathogeneses and Imaging Features of Cerebral White Matter Lesions of Vascular Origins

White matter lesion (WML), also known as white matter hyperintensities or leukoaraiosis, was first termed in 1986 to describe the hyperintense signals on T2-weighted imaging (T2WI) and fluid-attenuated inversion recovery (FLAIR) maps. Over the past decades, a growing body of pathophysiological findings regarding WMLs have been discovered and discussed. Currently, the generally accepted WML pathogeneses mainly include hypoxia-ischemia, endothelial dysfunction, blood-brain barrier disruption, and infiltration of inflammatory mediators or cytokines. However, none of them can explain the whole dynamics of WML formation. Herein, we primarily focus on the pathogeneses and neuroimaging features of vascular WMLs. To achieve this goal, we searched papers with any type published in PubMed from 1950 to 2020 and cross-referenced the keywords including “leukoencephalopathy”, “leukoaraiosis”, “white matter hyperintensity”, “white matter lesion”, “pathogenesis”, “pathology”, “pathophysiology”, and “neuroimaging”. Moreover, references of the selected articles were browsed and searched for additional pertinent articles. We believe this work will supply the robust references for clinicians to further understand the different WML patterns of varying vascular etiologies and thus make customized treatment.

Bilateral Distance Partition of Periventricular and Deep White Matter Hyperintensities: Performance of the Method in the Aging Brain

RATIONALE AND OBJECTIVES

Periventricular and deep white matter hyperintensities (WMHs) in the elderly have been reported with distinctive roles in the progression of cognitive decline and dementia. However, the definition of these two subregions of WMHs is arbitrary and varies across studies. Here, we evaluate three partition methods for WMH subregions, including two widely used conventional methods (CV & D10) and one novel method based on bilateral distance (BD).

MATERIALS AND METHODS

The three partition methods were assessed on the MRI scans of 60 subjects, with 20 normal control, 20 mild cognitive impairment, and 20 Alzheimer's disease (AD). Resulting WMH subregional volumes were (1) compared among different partition methods and subject groups, and (2) tested for clinical associations with cognition and dementia. Inter-rater, intrarater, and interscan reproducibility of WMHs volumes were tested on 12 randomly selected subjects from the 60.

RESULTS

For all three partition methods, increased periventricular WMHs were found for AD subjects over normal control. For BD and D10, but not CV method, increased Periventricular WMHs were found for AD subjects over mild cognitive impairment. Significant correlations were found between PVWMHs and Mini-Mental State Examination, Montreal Cognitive Assessment, and Clinical Dementia Rating scores. Furthermore, PVWMHs under BD partition showed higher correlations than D10 and CV. High intrarater and interscan reproducibility (ICCA = 0.998 and 0.992 correspondingly) and substantial inter-rater reproducibility (ICCA = 0.886) were detected.

CONCLUSION

Different WMH partition methods showed comparable diagnostic abilities. The proposed BD method showed advantages in quantifying PVWMH over conventional CV and D10 methods, in terms of higher consistency, larger contrast, and higher diagnosis accuracy. Furthermore, the PVWMH under BD partition showed stronger clinical correlations than conventional methods.

The Nitrate-Nitrite-Nitric Oxide Pathway on Healthy Ageing: A Review of Pre-clinical and Clinical Data on the Impact of Dietary Nitrate in the Elderly

We are living longer. Are we living healthier? As we age, cellular and molecular damage reshape our physiological responses towards environmental and endogenous stimuli. The free radical theory of ageing has been proposed long before ageing has been considered a “scientific discipline” and, since then, has been discussed and upgraded as a major contributor to aberrant ageing. Assuming that ageing results merely from the accumulation of oxidative modifications of biomolecules is not only a simplistic and reductive view of such a complex and dynamic process, but also free radicals and related oxidants are now considered pivotal signalling molecules. The fine modulation of critical signalling pathways by redox compounds demands a novel approach to tackle the role of free radicals in ageing. Nitric oxide (^⋅NO) is a paradigmatic example given its biological functions in cardiovascular, neurologic and immune systems. In addition to the canonical ^⋅NO synthesis by a family of enzymes, nitrate from green leafy vegetables, is reduced to nitrite in the oral cavity which is further reduced to ^⋅NO in the stomach. Boosting this nitrate-nitrite-NO pathway has been shown to improve gastrointestinal, cardiovascular, metabolic and cognitive performance both in humans and in animal models of disease. In the elderly, nitrate-derived ^⋅NO has been shown improve several physiological functions that typically decline during ageing. In this paper, the role of nitrate and derived nitrogen oxides will be discussed while reviewing pre-clinical and clinical data on the cardiovascular, neuronal, musculoskeletal and metabolic effects of nitrate during healthy ageing.

The aging venous system: from varicosities to vascular cognitive impairment

Aging-induced pathological alterations of the circulatory system play a critical role in morbidity and mortality of older adults. While the importance of cellular and molecular mechanisms of arterial aging for increased cardiovascular risk in older adults is increasingly appreciated, aging processes of veins are much less studied and understood than those of arteries. In this review, age-related cellular and morphological alterations in the venous system are presented. Similarities and dissimilarities between arterial and venous aging are highlighted, and shared molecular mechanisms of arterial and venous aging are considered. The pathogenesis of venous diseases affecting older adults, including varicose veins, chronic venous insufficiency, and deep vein thrombosis, is discussed, and the potential contribution of venous pathologies to the onset of vascular cognitive impairment and neurodegenerative diseases is emphasized. It is our hope that a greater appreciation of the cellular and molecular processes of vascular aging will stimulate further investigation into strategies aimed at preventing or retarding age-related venous pathologies.

Internal Jugular Vein Velocity and Spontaneous Echo Contrast Correlate with Alzheimer's Disease and Cognitive Function

BACKGROUND

Many issues persist in the today's Alzheimer's disease (AD) screening and the breakthrough method is desired.

OBJECTIVE

We aim to validate the association between venous reflux and AD, and to develop a new method for AD screening.

METHODS

We examined spontaneous echo contrast, area, diameter, retrograde velocity, and anterograde velocity of the bilateral cervical internal jugular vein (IJV) using carotid ultrasonography.

RESULTS

A total of 112 patients participated in this study, with 26 diagnosed as AD. The proportion of both or either IJV spontaneous echo contrast (+) occupied 25 of total 26 AD patients, which showed 96.2%of sensitivity and 98.5%negative predictive value. The IJV velocities also showed significant correlation with AD diagnosis, although the IJV area or diameter did not.

CONCLUSION

Our results indicate that the validation of the spontaneous echo contrast or velocities of the IJV are convenient AD diagnosis screening methods and that the venous reflux disturbance correlates with AD development.

Immunoreactivity and a new staining method of monocarboxylate transporter 1 located in endothelial cells of cerebral vessels of human brain in distinguishing cerebral venules from arterioles

Distinguishing brain venules from arterioles with arteriolosclerosis is less reliable using traditional staining methods. We aimed to immunohistochemically assess the monocarboxylate transporter 1 (MCT1), a specific marker of venous endothelium found in rodent studies, in different caliber vessels in human brains. Both largeand small-caliber cerebral vessels were dissected from four autopsy donors. Immunoreactivity for MCT1 was examined in all autopsied human brain tissues, and then each vessel was identified by neuropathologists using hematoxylin and eosin stain, the Verhoeff's Van Gieson stain, immunohistochemical stain with antibodies for α-smooth muscle actin and MCT1 in sequence. A total of 61 cerebral vessels, including 29 arteries and 32 veins were assessed. Immunoreactivity for MCT1 was observed in the endothelial cells of various caliber veins as well as the capillaries, whereas that was immunenegative in the endothelium of arteries. The different labeling patterns for MCT1 could aid in distinguishing various caliber veins from arteries, whereas assessment using the vessel shape, the internal elastic lamina, and the pattern of smooth muscle fibers failed to make the distinction between small-caliber veins and sclerotic arterioles. In conclusion, MCT1 immunohistochemical staining is a sensitive and reliable method to distinguish cerebral veins from arteries.

Microvessel stenosis, enlarged perivascular spaces, and fibrinogen deposition are associated with ischemic periventricular white matter hyperintensities

Periventricular white matter hyperintensities (pvWMH) are neuroimaging abnormalities surrounding the lateral ventricles that are apparent on magnetic resonance imaging (MRI). They are associated with age, neurodegenerative disease, and cerebrovascular risk factors. While pvWMH ultimately represent a loss of white matter structural integrity, the pathological causes are heterogeneous in nature, and currently, cannot be distinguished using neuroimaging alone. pvWMH could occur because of a combination of small vessel disease (SVD), ependymal loss, blood–brain barrier dysfunction, and microgliosis. In this study we aimed to characterize microvascular stenosis, fibrinogen extravasation, and microgliosis within pvWMH with and without imaging evidence of periventricular infarction. Using postmortem neuroimaging of human brains (n = 20), we identified pvWMH with and without periventricular infarcts (PVI). We performed histological analysis of microvessel stenosis, perivascular spaces, microgliosis, and immunohistochemistry against fibrinogen as a measure of serum protein extravasation. Herein, we report distinctions between pvWMH with and without periventricular infarcts based on associations with microvessel stenosis, enlarged perivascular spaces, and fibrinogen IHC. Microvessel stenosis was significantly associated with PVI and with cellular deposition of fibrinogen in the white matter. The presence of fibrinogen was associated with PVI and increased number of microglia. These findings suggest that neuroimaging‐based detection of infarction within pvWMH may help distinguish more severe lesions, associated with underlying microvascular disease and BBB dysfunction, from milder pvWMH that are a highly frequent finding on MRI.

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.

Age-related changes in cerebrovascular health and their effects on neural function and cognition: A comprehensive review

The process of aging includes changes in cellular biology that affect local interactions between cells and their environments and eventually propagate to systemic levels. In the brain, where neurons critically depend on an efficient and dynamic supply of oxygen and glucose, age-related changes in the complex interaction between the brain parenchyma and the cerebrovasculature have effects on health and functioning that negatively impact cognition and play a role in pathology. Thus, cerebrovascular health is considered one of the main mechanisms by which a healthy lifestyle, such as habitual cardiorespiratory exercise and a healthful diet, could lead to improved cognitive outcomes with aging. This review aims at detailing how the physiology of the cerebral vascular system changes with age and how these changes lead to differential trajectories of cognitive maintenance or decline. This provides a framework for generating specific mechanistic hypotheses about the efficacy of proposed interventions and lifestyle covariates that contribute to enhanced cognitive well-being. Finally, we discuss the methodological implications of age-related changes in the cerebral vasculature for human cognitive neuroscience research and propose directions for future experiments aimed at investigating age-related changes in the relationship between physiology and cognitive mechanisms.

Increased extracellular fluid is associated with white matter fiber degeneration in CADASIL: in vivo evidence from diffusion magnetic resonance imaging

Background

White matter hyperintensities (WMHs) are one of the hallmarks of cerebral small vessel disease (CSVD), but the pathological mechanisms underlying WMHs remain unclear. Recent studies suggest that extracellular fluid (ECF) is increased in brain regions with WMHs. It has been hypothesized that ECF accumulation may have detrimental effects on white matter microstructure. To test this hypothesis, we used cerebral autosomal-dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL) as a unique CSVD model to investigate the relationships between ECF and fiber microstructural changes in WMHs.

Methods

Thirty-eight CADASIL patients underwent 3.0 T MRI with multi-model sequences. Parameters of free water (FW) and apparent fiber density (AFD) obtained from diffusion-weighted imaging (b = 0 and 1000 s/mm²) were respectively used to quantify the ECF and fiber density. WMHs were split into four subregions with four levels of FW using quartiles (FWq1 to FWq4) for each participant. We analyzed the relationships between FW and AFD in each subregion of WMHs. Additionally, we tested whether FW of WMHs were associated with other accompanied CSVD imaging markers including lacunes and microbleeds.

Results

We found an inverse correlation between FW and AFD in WMHs. Subregions of WMHs with high-level of FW (FWq3 and FWq4) were accompanied with decreased AFD and with changes in FW-corrected diffusion tensor imaging parameters. Furthermore, FW was also independently associated with lacunes and microbleeds.

Conclusions

Our study demonstrated that increased ECF was associated with WM degeneration and the occurrence of lacunes and microbleeds, providing important new insights into the role of ECF in CADASIL pathology. Improving ECF drainage might become a therapeutic strategy in future.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12987-021-00264-1.

The association between transthoracic echocardiogram parameters and white matter hyperintensities

OBJECTIVE

Identify abnormal cardiac chamber size and hemodynamic parameters on transthoracic echocardiogram (TTE) as predictors of advancing cerebral small vessel disease (CSVD) on brain magnetic resonance imaging (MRI).

MATERIALS AND METHODS

A retrospective chart review of adults with a brain MRI and a 2-dimensional TTE was performed. WMH measured by the Fazekas score served as the primary outcome. We fit multivariate ordinal logistic regression models to the Fazekas score with the individual predictors of the TTE measurements and adjusted for potential confounders.

RESULTS

132 individuals were included. Cardiac functional markers were not significant, including tricuspid annular plane systolic excursion (p = 0.818), right ventricular ejection fraction (p = 0.818) and left ventricular ejection fraction (p = 0.673). Cardiac structural markers included right atrial area (p = 0.247), right ventricular internal diameter (RVID, p = 0.020) and left atrial area (LAA, p = 0.041). RVID and LAA were identified as being predictors, although the direction of the association suggested that normal values resulted in more WMH. Analysis of isolated DWM or PVWM Fazekas scores were not associated with cardiac structure or function.

CONCLUSIONS

In our study, we found that normal LAA and RVID values were associated with an increased degree of WMH on MRI. This finding may represent earlier identification of WMH prior to TTE cardiac changes. Future studies are needed for more robust quantitative comparison as well as evaluation prospectively of the association between cardiac chamber sizes and development of WMH.

An Overview of Venous Abnormalities Related to the Development of Lesions in Multiple Sclerosis

The etiology of multiple sclerosis (MS) is currently understood to be autoimmune. However, there is a long history and growing evidence for disrupted vasculature and flow within the disease pathology. A broad review of the literature related to vascular effects in MS revealed a suggestive role for abnormal flow in the medullary vein system. Evidence for venous involvement in multiple sclerosis dates back to the early pathological work by Charcot and Bourneville, in the mid-nineteenth century. Pioneering work by Adams in the 1980s demonstrated vasculitis within the walls of veins and venules proximal to active MS lesions. And more recently, magnetic resonance imaging (MRI) has been used to show manifestations of the central vein as a precursor to the development of new MS lesions, and high-resolution MRI using Ferumoxytol has been used to reveal the microvasculature that has previously only been demonstrated in cadaver brains. Both approaches may shed new light into the structural changes occurring in MS lesions. The material covered in this review shows that multiple pathophysiological events may occur sequentially, in parallel, or in a vicious circle which include: endothelial damage, venous collagenosis and fibrin deposition, loss of vessel compliance, venous hypertension, perfusion reduction followed by ischemia, medullary vein dilation and local vascular remodeling. We come to the conclusion that a potential source of MS lesions is due to locally disrupted flow which in turn leads to remodeling of the medullary veins followed by endothelial damage with the subsequent escape of glial cells, cytokines, etc. These ultimately lead to the cascade of inflammatory and demyelinating events which ensue in the course of the disease.

Brain deep medullary veins on 3-T MRI in a population-based cohort

Our aim is to investigate whether vascular risk factors are associated with cerebral deep medullary veins (DMVs) and whether DMVs are associated with MRI markers of cerebral small vessel disease (CSVD) or risk of stroke. In a community-based cohort of 1056 participants (mean age 55.7 years), DMVs were identified on susceptibility-weighted imaging (SWI) and counted in periventricular regions. Neuroimaging markers including lacunes, whiter matter hyperintensity (WMH), microbleeds, enlarged perivascular space, and brain atrophy were evaluated. The number of DMVs decreased with age (p = 0.007). After adjusting for age and sex, the number of DMVs was not associated with traditional vascular risk factors. Fewer DMVs was associated with increase of WMH and lacunes, but the association vanished after adjustment for vascular risk factors. However, fewer DMVs were independently associated with brain atrophy (p < 0.001). DMVs were not associated with three-year risk of stroke. Our results suggest that DMV is significantly different from other MRI markers of CSVD regarding risk factors, association with other CSVD markers, and risk of stroke. Nonetheless, the significant association between DMV and brain atrophy suggested the potential role of venules in age-related neurodegenerative process, which deserves further investigation.

Homocysteine in Neurology: A Possible Contributing Factor to Small Vessel Disease

Homocysteine (Hcy) is a sulfur-containing amino acid generated during methionine metabolism, accumulation of which may be caused by genetic defects or the deficit of vitamin B12 and folate. A serum level greater than 15 micro-mols/L is defined as hyperhomocysteinemia (HHcy). Hcy has many roles, the most important being the active participation in the transmethylation reactions, fundamental for the brain. Many studies focused on the role of homocysteine accumulation in vascular or degenerative neurological diseases, but the results are still undefined. More is known in cardiovascular disease. HHcy is a determinant for the development and progression of inflammation, atherosclerotic plaque formation, endothelium, arteriolar damage, smooth muscle cell proliferation, and altered-oxidative stress response. Conversely, few studies focused on the relationship between HHcy and small vessel disease (SVD), despite the evidence that mice with HHcy showed a significant end-feet disruption of astrocytes with a diffuse SVD. A severe reduction of vascular aquaporin-4-water channels, lower levels of high-functioning potassium channels, and higher metalloproteinases are also observed. HHcy modulates the N-homocysteinylation process, promoting a pro-coagulative state and damage of the cellular protein integrity. This altered process could be directly involved in the altered endothelium activation, typical of SVD and protein quality, inhibiting the ubiquitin-proteasome system control. HHcy also promotes a constant enhancement of microglia activation, inducing the sustained pro-inflammatory status observed in SVD. This review article addresses the possible role of HHcy in small-vessel disease and understands its pathogenic impact.