The pathobiology of vascular dementia

The emerging role of nitric oxide in the synaptic dysfunction of vascular dementia

With an increase in global aging, the number of people affected by cerebrovascular diseases is also increasing, and the incidence of vascular dementia-closely related to cerebrovascular risk-is increasing at an epidemic rate. However, few therapeutic options exist that can markedly improve the cognitive impairment and prognosis of vascular dementia patients. Similarly in Alzheimer's disease and other neurological disorders, synaptic dysfunction is recognized as the main reason for cognitive decline. Nitric oxide is one of the ubiquitous gaseous cellular messengers involved in multiple physiological and pathological processes of the central nervous system. Recently, nitric oxide has been implicated in regulating synaptic plasticity and plays an important role in the pathogenesis of vascular dementia. This review introduces in detail the emerging role of nitric oxide in physiological and pathological states of vascular dementia and summarizes the diverse effects of nitric oxide on different aspects of synaptic dysfunction, neuroinflammation, oxidative stress, and blood-brain barrier dysfunction that underlie the progress of vascular dementia. Additionally, we propose that targeting the nitric oxide-sGC-cGMP pathway using certain specific approaches may provide a novel therapeutic strategy for vascular dementia.

Danggui-Shaoyao San alleviates cognitive impairment via enhancing HIF-1α/EPO axis in vascular dementia rats

ETHNOPHARMACOLOGICAL RELEVANCE

Invigorating blood circulation to remove blood stasis is a primary strategy in TCM for treating vascular dementia (VaD). Danggui-Shaoyao San (DSS), as a traditional prescription for neuroprotective activity, has been proved to be effective in VaD treatment. However, its precise molecular mechanisms remain incompletely understood.

AIM OF THE STUDY

The specific mechanism underlying the therapeutic effects of DSS on VaD was explored by employing network pharmacology as well as in vivo and in viro experiment validation.

MATERIALS AND METHODS

We downloaded components of DSS from the BATMAN-TCM database for target prediction. The intersection between the components of DSS and targets, PPI network, as well as GO and KEGG enrichment analysis were then performed. Subsequently, the potential mechanism of DSS predicted by network pharmacology was assessed and validated through VaD rat model induced by 2VO operation and CoCl2-treated PC12 cells. Briefly, the DSS extract were first quantified by HPLC. Secondly, the effect of DSS on VaD was studied using MWM test, HE staining and TUNEL assay. Finally, the molecular mechanism of DSS against VaD was validated by Western blot and RT-QPCR experiments.

RESULTS

Through network analysis, 137 active ingredients were obtained from DSS, and 67 potential targets associated with DSS and VaD were identified. GO and KEGG analysis indicated that the action of DSS on VaD primarily involves hypoxic terms and HIF-1 pathway. In vivo validation, cognitive impairment and neuron mortality were markedly ameliorated by DSS. Additionally, DSS significantly reduced the expression of proteins related to synaptic plasticity and neuron apoptosis including PSD-95, SYP, Caspase-3 and BCL-2. Mechanistically, we confirmed DSS positively modulated the expression of HIF-1α and its downstream proteins including EPO, p-EPOR, STAT5, EPOR, and AKT1 in the hippocampus of VaD rats as well as CoCl2-induced PC12 cells. HIF-1 inhibitor YC-1 significantly diminished the protection of DSS on CoCl2-induced PC12 cell damage, with decreased HIF-1α, EPO, EPOR expression.

CONCLUSION

Our results initially demonstrated DSS could exert neuroprotective effects in VaD. The pharmacological mechanism of DSS may be related to its positive regulation on HIF-1α/EPO pathway.

Modulation of gut microbiome in the treatment of neurodegenerative diseases: A systematic review

BACKGROUND AND AIMS

Microbiota plays an essential role in maintaining body health, through positive influences on metabolic, defensive, and trophic processes and on intercellular communication. Imbalance in intestinal flora, with the proliferation of harmful bacterial species (dysbiosis) is consistently reported in chronic illnesses, including neurodegenerative diseases (ND). Correcting dysbiosis can have a beneficial impact on the symptoms and evolution of ND. This review examines the effects of microbiota modulation through administration of probiotics, prebiotics, symbiotics, or prebiotics' metabolites (postbiotics) in patients with ND like multiple sclerosis (MS), Alzheimer's disease (AD), Parkinson's disease (PD) and amyotrophic lateral sclerosis (ALS).

METHODS

PubMed, Web of Science, Medline databases and ClinicalTrials.gov registry searches were performed using pre-/pro-/postbiotics and ND-related terms. Further references were obtained by checking relevant articles.

RESULTS

Although few compared to animal studies, the human studies generally show positive effects on disease-specific symptoms, overall health, metabolic parameters, on oxidative stress and immunological markers. Therapy with probiotics in various forms (mixtures of bacterial strains, fecal microbiota transplant, diets rich in fermented foods) exert favorable effects on patients' mental health, cognition, and quality of life, targeting pathogenetic ND mechanisms and inducing reparatory mechanisms at the cellular level. More encouraging results have been observed in prebiotic/postbiotic therapy in some ND.

CONCLUSIONS

The effects of probiotic-related interventions depend on the patients' ND stage and pre-existing allopathic medication. Further studies on larger cohorts and long term comprehensive neuropsychiatric, metabolic, biochemical testing, and neuroimaging monitoring are necessary to optimize therapeutic protocols in ND.

tPA supplementation preserves neurovascular and cognitive function in Tg2576 mice

INTRODUCTION

Amyloid beta (Aβ) impairs the cerebral blood flow (CBF) increase induced by neural activity (functional hyperemia). Tissue plasminogen activator (tPA) is required for functional hyperemia, and in mouse models of Aβ accumulation tPA deficiency contributes to neurovascular and cognitive impairment. However, it remains unknown if tPA supplementation can rescue Aβ-induced neurovascular and cognitive dysfunction.

METHODS

Tg2576 mice and wild-type littermates received intranasal tPA (0.8 mg/kg/day) or vehicle 5 days a week starting at 11 to 12 months of age and were assessed 3 months later.

RESULTS

Treatment of Tg2576 mice with tPA restored resting CBF, prevented the attenuation in functional hyperemia, and improved nesting behavior. These effects were associated with reduced cerebral atrophy and cerebral amyloid angiopathy, but not parenchymal amyloid.

DISCUSSION

These findings highlight the key role of tPA deficiency in the neurovascular and cognitive dysfunction associated with amyloid pathology, and suggest potential therapeutic strategies involving tPA reconstitution.

HIGHLIGHTS

Amyloid beta (Aβ) induces neurovascular dysfunction and impairs the increase of cerebral blood flow induced by neural activity (functional hyperemia). Tissue plasminogen activator (tPA) deficiency contributes to the neurovascular and cognitive dysfunction caused by Aβ. In mice with florid amyloid pathology intranasal administration of tPA rescues the neurovascular and cognitive dysfunction and reduces brain atrophy and cerebral amyloid angiopathy. tPA deficiency plays a crucial role in neurovascular and cognitive dysfunction induced by Aβ and tPA reconstitution may be of therapeutic value.

Neuroprotective effects of Gypenosides: A review on preclinical studies in neuropsychiatric disorders

Gynostemma pentaphyllum (Thunb.) Makino is a perennial creeping herb belonging to the Cucurbitaceae family that has a long history of usage in traditional oriental medicine. Gypenosides are the primary bioactive compounds in Gynostemma pentaphyllum. Because of the medicinal value of gypenosides, functional food and supplements containing gypenosides have been promoted and consumed with popularity, especially among Asian communities. This review presented the progress made in the research of pharmacological properties of gypenosides on diseases of the nervous system and their possible mechanism of action. To date, preclinical studies have demonstrated the therapeutic effects of gypenosides in alleviating neuropsychiatric disorders like depression, Parkinson's disease, Alzheimer's disease, secondary dementia, stroke, optic neuritis, etc. Pharmacological studies have discovered that gypenosides can modulate various major signaling pathways like NF-κB, Nrf2, AKT, ERK1/2, contributing to the neuroprotective properties. However, there is a dearth of clinical research on gypenosides, with current investigations on the compounds being mainly conducted in vitro and on animals. Future studies focusing on isolating and purifying novel gypenosides and investigations on exploring the potential molecular mechanism underlying their biological activities are warranted, which may serve as a foundation for further clinical trials for the betterment of human health.

Pin1-catalyzed conformational regulation after phosphorylation: A distinct checkpoint in cell signaling and drug discovery

Protein phosphorylation is one of the most common mechanisms regulating cellular signaling pathways, and many kinases and phosphatases are proven drug targets. Upon phosphorylation, protein functions can be further regulated by the distinct isomerase Pin1 through cis-trans isomerization. Numerous protein targets and many important roles have now been elucidated for Pin1. However, no tools are available to detect or target cis and trans conformation events in cells. The development of Pin1 inhibitors and stereo- and phospho-specific antibodies has revealed that cis and trans conformations have distinct and often opposing cellular functions. Aberrant conformational changes due to the dysregulation of Pin1 can drive pathogenesis but can be effectively targeted in age-related diseases, including cancers and neurodegenerative disorders. Here, we review advances in understanding the roles of Pin1 signaling in health and disease and highlight conformational regulation as a distinct signal transduction checkpoint in disease development and treatment.

Post-stroke cognitive impairment and brain hemorrhage are augmented in hypertensive mice

Hypertension is a major risk factor for both stroke and cognitive impairment, but it is unclear whether it may specifically affect post-stroke cognitive impairment. We assessed the effect of hypertension and/or stroke on brain injury, cognitive outcome, and the brain transcriptomic profile. C57BL/6J mice (n = 117; 3-5 mo.) received s.c. infusion of either saline or angiotensin II followed by sham surgery or photothrombotic stroke targeting the prefrontal cortex seven days later. Cognitive function was assessed with the Barnes maze and RNA sequencing was used to quantify transcriptomic changes in the brain. Angiotensin II treatment produced spontaneous hemorrhaging after stroke. In the Barnes maze, hypertensive mice that received stroke surgery had an increased escape latency compared to other groups (day 3: hypertensive + stroke = 166.6 ± 6.0 s vs. hypertensive + sham = 122.8 ± 13.8 s vs. normotensive + stroke = 139.9 ± 10.1 s vs. normotensive + sham = 101.9 ± 16.7 s), consistent with impaired cognition. RNA sequencing revealed >1500 differentially expressed genes related to neuroinflammation in hypertensive + stroke vs. normotensive + stroke, which included genes associated with apoptosis, microRNAs, autophagy, anti-cognitive biomarkers and Wnt signaling. Overall, we show that the combination of hypertension and stroke resulted in greater learning impairment and brain injury.

Complex relationships of socioeconomic status with vascular and Alzheimer's pathways on cognition

INTRODUCTION

AD and CVD, which frequently co-occur, are leading causes of age-related cognitive decline. We assessed how demographic factors, socioeconomic status (SES) as indicated by education and occupation, vascular risk factors, and a range of biomarkers associated with both CVD (including white matter hyperintensities [WMH], diffusion MRI abnormalities, infarctions, and microbleeds) and AD (comprising amyloid-PET and tau-PET) collectively influence cognitive function.

METHODS

In this cross-sectional population study, structural equation models were utilized to understand these associations in 449 participants (mean age (SD) = 74.5 (8.4) years; 56% male; 7.5% cognitively impaired).

RESULTS

(1) Higher SES had a protective effect on cognition with mediation through the vascular pathway. (2) The effect of amyloid directly on cognition and through tau was 11-fold larger than the indirect effect of amyloid on cognition through WMH. (3) There is a significant effect of vascular risk on tau deposition.

DISCUSSION

The utilized biomarkers captured the impact of CVD and AD on cognition. The overall effect of vascular risk and SES on these biomarkers are complex and need further investigation.

The Role of Zinc in the Development of Vascular Dementia and Parkinson's Disease and the Potential of Carnosine as Their Therapeutic Agent

Synaptic zinc ions (Zn2+) play an important role in the development of vascular dementia (VD) and Parkinson's disease (PD). In this article, we reviewed the current comprehension of the Zn2+-induced neurotoxicity that leads to the pathogenesis of these neuronal diseases. Zn2+-induced neurotoxicity was investigated by using immortalised hypothalamic neurons (GT1-7 cells). This cell line is useful for the development of a rapid and convenient screening system for investigating Zn2+-induced neurotoxicity. GT1-7 cells were also used to search for substances that prevent Zn2+-induced neurotoxicity. Among the tested substances was a protective substance in the extract of Japanese eel (Anguilla japonica), and we determined its structure to be like carnosine (β-alanylhistidine). Carnosine may be a therapeutic drug for VD and PD. Furthermore, we reviewed the molecular mechanisms that involve the role of carnosine as an endogenous protector and its protective effect against Zn2+-induced cytotoxicity and discussed the prospects for the future therapeutic applications of this dipeptide for neurodegenerative diseases and dementia.

Mapping vascular network architecture in primate brain using ferumoxytol-weighted laminar MRI

Mapping the vascular organization of the brain is of great importance across various domains of basic neuroimaging research, diagnostic radiology, and neurology. However, the intricate task of precisely mapping vasculature across brain regions and cortical layers presents formidable challenges, resulting in a limited understanding of neurometabolic factors influencing the brain's microvasculature. Addressing this gap, our study investigates whole-brain vascular volume using ferumoxytol-weighted laminar-resolution multi-echo gradient-echo imaging in macaque monkeys. We validate the results with published data for vascular densities and compare them with cytoarchitecture, neuron and synaptic densities. The ferumoxytol-induced change in transverse relaxation rate (ΔR2*), an indirect proxy measure of cerebral blood volume (CBV), was mapped onto twelve equivolumetric laminar cortical surfaces. Our findings reveal that CBV varies 3-fold across the brain, with the highest vascular volume observed in the inferior colliculus and lowest in the corpus callosum. In the cerebral cortex, CBV is notably high in early primary sensory areas and low in association areas responsible for higher cognitive functions. Classification of CBV into distinct groups unveils extensive replication of translaminar vascular network motifs, suggesting distinct computational energy supply requirements in areas with varying cytoarchitecture types. Regionally, baseline R2* and CBV exhibit positive correlations with neuron density and negative correlations with receptor densities. Adjusting image resolution based on the critical sampling frequency of penetrating cortical vessels, allows us to delineate approximately 30% of the arterial-venous vessels. Collectively, these results mark significant methodological and conceptual advancements, contributing to the refinement of cerebrovascular MRI. Furthermore, our study establishes a linkage between neurometabolic factors and the vascular network architecture in the primate brain.

Molecular cross-talk between long COVID-19 and Alzheimer's disease

The long COVID (coronavirus disease), a multisystemic condition following severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection, is one of the widespread problems. Some of its symptoms affect the nervous system and resemble symptoms of Alzheimer's disease (AD)-a neurodegenerative condition caused by the accumulation of amyloid beta and hyperphosphorylation of tau proteins. Multiple studies have found dependence between these two conditions. Patients with Alzheimer's disease have a greater risk of SARS-CoV-2 infection due to increased levels of angiotensin-converting enzyme 2 (ACE2), and the infection itself promotes amyloid beta generation which enhances the risk of AD. Also, the molecular pathways are alike-misregulations in folate-mediated one-carbon metabolism, a deficit of Cq10, and disease-associated microglia. Medical imaging in both of these diseases shows a decrease in the volume of gray matter, global brain size reduction, and hypometabolism in the parahippocampal gyrus, thalamus, and cingulate cortex. In some studies, a similar approach to applied medication can be seen, including the use of amino adamantanes and phenolic compounds of rosemary. The significance of these connections and their possible application in medical practice still needs further study but there is a possibility that they will help to better understand long COVID.

Cognitive dysfunction in diabetes-related foot complications: A cohort study

Objective

Mild-moderate cognitive impairment has been identified in general diabetes, and early evidence indicates cognitive reductions may be more pronounced in those with diabetes-related foot complications (DRFC). Cognitive difficulties may impede treatment engagement and self-management. This requires further explication to optimise patient care and outcomes. The current study aimed to characterise cognitive function in people with DRFC using comprehensive cognitive measures.

Method

This cross-sectional cohort study recruited 80 adult participants (M age  = 63.38, SD = 11.40, range = 30 - 89) from the Royal Melbourne Hospital Diabetic Foot Unit in Victoria, Australia, all with DRFC. Each completed a comprehensive cognitive battery (memory, attention, executive functions) and scores were calculated using age-matched population norms, where available.

Results

On the majority of tasks, DRFC participants performed significantly worse than age-matched norms, with the largest decrements seen in inhibition control, verbal memory, verbal abstract reasoning and working memory. Small to moderate reductions were also seen in visual learning, verbal fluency, processing speed and premorbid functioning. Demographic (lower education, male gender) and clinical factors (higher HbA1c, macrovascular and microvascular disease, longer diabetes duration) were associated with poorer cognitive functioning.

Conclusions

Marked reductions in cognitive functioning were found in individuals with DRFC, predominantly in the domains of verbal memory and executive functioning. Lower education, male gender and indicators of diabetes severity, such as vascular disease, are associated with heightened risk for poorer cognitive functioning. As DRFCs are a serious complication with devastating outcomes if not successfully managed, cognitive barriers to self-management must be addressed to optimise treatment.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-023-01381-4.

Modeling oxygen transport in the brain: An efficient coarse-grid approach to capture perivascular gradients in the parenchyma

Recent progresses in intravital imaging have enabled highly-resolved measurements of periarteriolar oxygen gradients (POGs) within the brain parenchyma. POGs are increasingly used as proxies to estimate the local baseline oxygen consumption, which is a hallmark of cell activity. However, the oxygen profile around a given arteriole arises from an interplay between oxygen consumption and delivery, not only by this arteriole but also by distant capillaries. Integrating such interactions across scales while accounting for the complex architecture of the microvascular network remains a challenge from a modelling perspective. This limits our ability to interpret the experimental oxygen maps and constitutes a key bottleneck toward the inverse determination of metabolic rates of oxygen. We revisit the problem of parenchymal oxygen transport and metabolism and introduce a simple, conservative, accurate and scalable direct numerical method going beyond canonical Krogh-type models and their associated geometrical simplifications. We focus on a two-dimensional formulation, and introduce the concepts needed to combine an operator-splitting and a Green's function approach. Oxygen concentration is decomposed into a slowly-varying contribution, discretized by Finite Volumes over a coarse cartesian grid, and a rapidly-varying contribution, approximated analytically in grid-cells surrounding each vessel. Starting with simple test cases, we thoroughly analyze the resulting errors by comparison with highly-resolved simulations of the original transport problem, showing considerable improvement of the computational-cost/accuracy balance compared to previous work. We then demonstrate the model ability to flexibly generate synthetic data reproducing the spatial dynamics of oxygen in the brain parenchyma, with sub-grid resolution. Based on these synthetic data, we show that capillaries distant from the arteriole cannot be overlooked when interpreting POGs, thus reconciling recent measurements of POGs across cortical layers with the fundamental idea that variations of vascular density within the depth of the cortex may reveal underlying differences in neuronal organization and metabolic load.

Peripheral vascular dysfunction and the aging brain

Aging is the greatest non-modifiable risk factor for most diseases, including cardiovascular diseases (CVD), which remain the leading cause of mortality worldwide. Robust evidence indicates that CVD are a strong determinant for reduced brain health and all-cause dementia with advancing age. CVD are also closely linked with peripheral and cerebral vascular dysfunction, common contributors to the development and progression of all types of dementia, that are largely driven by excessive levels of oxidative stress (e.g., reactive oxygen species [ROS]). Emerging evidence suggests that several fundamental aging mechanisms (e.g., "hallmarks" of aging), including chronic low-grade inflammation, mitochondrial dysfunction, cellular senescence and deregulated nutrient sensing contribute to excessive ROS production and are common to both peripheral and cerebral vascular dysfunction. Therefore, targeting these mechanisms to reduce ROS-related oxidative stress and improve peripheral and/or cerebral vascular function may be a promising strategy to reduce dementia risk with aging. Investigating how certain lifestyle strategies (e.g., aerobic exercise and diet modulation) and/or select pharmacological agents (natural and synthetic) intersect with aging "hallmarks" to promote peripheral and/or cerebral vascular health represent a viable option for reducing dementia risk with aging. Therefore, the primary purpose of this review is to explore mechanistic links among peripheral vascular dysfunction, cerebral vascular dysfunction, and reduced brain health with aging. Such insight and assessments of non-invasive measures of peripheral and cerebral vascular health with aging might provide a new approach for assessing dementia risk in older adults.

Effects of schisandrin B on hypoxia-related cognitive function and protein expression in vascular dementia rats

Vascular dementia (VD) a heterogenous group of brain disorders in which cognitive impairment is attributable to vascular risk factors and cerebrovascular disease. A common phenomenon in VD is a dysfunctional cerebral regulatory mechanism associated with insufficient cerebral blood flow, ischemia and hypoxia. Under hypoxic conditions oxygen supply to the brain results in neuronal death leading to neurodegenerative diseases including Alzheimer's (AD) and VD. In conditions of hypoxia and low oxygen perfusion, expression of hypoxia-inducible factor 1 alpha (HIF-1α) increases under conditions of low oxygen and low perfusion associated with upregulation of expression of hypoxia-upregulated mitochondrial movement regulator (HUMMR), which promotes anterograde mitochondrial transport by binding with trafficking protein kinesin 2 (TRAK2). Schisandrin B (Sch B) an active component derived from Chinese herb Wuweizi prevented β-amyloid protein induced morphological alterations and cell death using a SH-SY5Y neuronal cells considered an AD model. It was thus of interest to determine whether Sch B might also alleviate VD using a rat bilateral common carotid artery occlusion (BCAO) dementia model. The aim of this study was to examine the effects of Sch B in BCAO on cognitive functions such as Morris water maze test and underlying mechanisms involving expression of HIF-1α, TRAK2, and HUMMR levels. The results showed that Sch B improved learning and memory function of rats with VD and exerted a protective effect on the hippocampus by inhibition of protein expression of HIF-1α, TRAK2, and HUMMR factors. Evidence indicates that Sch B may be considered as an alternative in VD treatment.

Increased Expression of VCAM1 on Brain Endothelial Cells Drives Blood-Brain Barrier Impairment Following Chronic Cerebral Hypoperfusion

Chronic cerebral hypoperfusion (CCH)-triggered blood-brain barrier (BBB) dysfunction is a core pathological change occurring in vascular dementia (VD). Despite the recent advances in the exploration of the structural basis of BBB impairment and the routes of entry of harmful compounds after a BBB leakage, the molecular mechanisms inducing BBB impairment remain largely unknown in terms of VD. Here, we employed a CCH-induced VD model and discovered increased vascular cell adhesion molecule 1 (VCAM1) expression on the brain endothelial cells (ECs). The expression of VCAM1 was directly correlated with the severity of BBB impairment. Moreover, the VCAM1 expression was associated with different regional white matter lesions. Furthermore, a compound that could block VCAM1 activation, K-7174, was also found to alleviate BBB leakage and protect the white matter integrity, whereas pharmacological manipulation of the BBB leakage did not affect the VCAM1 expression. Thus, our results demonstrated that VCAM1 is an important regulator that leads to BBB dysfunction following CCH. Blocking VCAM1-mediated BBB impairment may thus offer a new strategy to treat CCH-related neurodegenerative diseases.

2-(4-Methylthiazol-5-yl) Ethyl Nitrate Hydrochloride Ameliorates Cognitive Impairment via Modulation of Oxidative Stress and Nuclear Factor Kappa B (NF-κB) Signaling Pathway in Chronic Cerebral Hypoperfusion-Associated Spontaneously Hypertensive Rats

Hypertension reduces the bioavailability of vascular nitric oxide (NO) and contributes to the onset of vascular dementia (VaD). A loss of NO bioavailability increases inflammation and oxidative stress. 2-(4-Methylthiazol-5-yl) ethyl nitrate hydrochloride (W1302) is a novel nitric oxide donor (NOD) which is undergoing phase I clinical trials in China for the treatment of VaD. In this study, we investigated the protective effects of W1302 in VaD rats induced by the permanent occlusion of a bilateral common carotid arteries model related to spontaneous hypertension (SHR-2VO), and we further explored the underlying mechanisms. Nimodipine was used as a positive control. Our results showed that W1302 treatment for 4 weeks (10 mg/Kg/day) exhibited stronger improvement in the spatial learning and memory deficits in SHR-2VO rats compared with nimodipine with slightly lower systolic blood pressure (SBP). Meanwhile, W1302 treatment significantly increased NO and cGMP production, restored mitochondrial membrane potential and attenuated oxidative stress as evidenced by increasing ATP production and reducing malondialdehyde (MDA) levels in the brain. Furthermore, W1302 treatment markedly inhibited the iNOS activity and decreased TNF-α expression via inhibiting the nuclear factor kappa B (NF-κB) signaling pathway. Nimodipine treatment also restored these aberrant changes, but its ATP production was weaker than that of W1302, and there was no significant effect on NO release. Taken together, W1302 exhibited beneficial effects on complications in VaD with hypertension, which is involved in suppressing oxidative damage, and the inflammatory reaction might be mediated by an increase in NO release. Therefore, W1302 has therapeutic potential for the treatment of VaD caused by chronic cerebral hypoperfusion-associated spontaneous hypertension.

BDNF Signaling in Vascular Dementia and Its Effects on Cerebrovascular Dysfunction, Synaptic Plasticity, and Cholinergic System Abnormality

Vascular dementia (VaD) is the second most common type of dementia and is characterized by memory impairment, blood-brain barrier disruption, neuronal cell loss, glia activation, impaired synaptic plasticity, and cholinergic system abnormalities. To effectively prevent and treat VaD a good understanding of the mechanisms underlying its neuropathology is needed. Brain-derived neurotrophic factor (BDNF) is an important neurotrophic factor with multiple functions in the systemic circulation and the central nervous system and is known to regulate neuronal cell survival, synaptic formation, glia activation, and cognitive decline. Recent studies indicate that when compared with normal subjects, patients with VaD have low serum BDNF levels and that BDNF deficiency in the serum and cerebrospinal fluid is an important indicator of VaD. Here, we review current knowledge on the role of BDNF signaling in the pathology of VaD, such as cerebrovascular dysfunction, synaptic dysfunction, and cholinergic system impairment.

Circulating cytokines and vascular dementia: A bi-directional Mendelian randomization study

Inflammatory responses are associated with the development of vascular dementia (VaD). Circulating cytokines modulate the inflammatory response and are important for the immune system. To further elucidate the role of the immune system in VaD, we used Mendelian randomization (MR) to comprehensively and bi-directionally assess the role of circulating cytokines in VaD. Using state-of-the-art genome-wide association studies, we primarily assessed whether different genetic levels of 41 circulating cytokines affect the risk of developing VaD and, in turn, whether the genetic risk of VaD affects these circulating cytokines. We used inverse variance weighting (IVW) and several other MR methods to assess the bidirectional causality between circulating cytokines and VaD, and performed sensitivity analyses. Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) was inversely associated with VaD risk [odds ratio (OR): 0.74, 95 % confidence interval (CI): 0.60-0.92, P = 0.007, 0.007]. VaD was associated with seven circulating cytokines: macrophage inflammatory protein 1b (MIP-1 beta) [OR: 1.05, 95 % CI: 1.01-1.08, P = 0.009], Interleukin-12p70 (IL-12) [OR: 1.04, 95 % CI: 1.00-1.08, P = 0.047], Interleukin-17 (IL-17) [OR: 1.04, 95 % CI: 1.00-1.07, P = 0.038], Interleukin-7 (IL-7) [OR: 1.07, 95 % CI: 1.02-1.12, P = 0.009], Interferon gamma (IFN-γ) [OR: 1.03, 95 % CI: 1.00-1.07, P = 0.046], Granulocyte-colony stimulating factor (GCSF) [OR: 1.06, 95 % CI: 1.02-1.09, P = 0.001], Fibroblast growth factor (FGF) [P = 0.001], and Fibroblast growth factor (FGF) [P = 0.001]. Fibroblast growth factor basic (FGF-Basic) [OR: 1.04, 95 % CI: 1.01-1.08, P = 0.02] were positively correlated. Circulating cytokines are associated with VaD, and further studies are needed to determine whether they are effective targets for intervention to prevent or treat VaD.

Comorbidities in patients with vascular dementia and Alzheimer's disease with Neuropsychiatric symptoms

INTRODUCTION

This study aimed to examine baseline risk factors in Alzheimer's Disease (AD) and Vascular dementia (VaD) patients with neuropsychiatry symptoms (NPS), and determine whether specific risk factors differ by subtypes of dementia for AD and VaD patients with NPS.

METHODS

A retrospective data analysis was conducted to evaluate similarities and differences in the risk factors for AD and VaD with NPS. The analysis included 2949 patients with VaD and 6341 patients with clinical confirmation of AD and VaD with or without NPS collected between February 2016 and August 2021. The multivariate logistic regression analysis was used to determine the risk factors associated with AD and VaD with NPS, by predicting the increasing odds (odds ratios (ORs) of an association of a specific baseline risk factor with AD or VaD with NPS. The validity of the regression models was tested using a Hosmer-Lemeshow test, while the Receiver Operating Curve (ROC) was used to test the sensitivity of the models.

RESULTS

In the adjusted analysis TSH (OR = 1.781, 95 % CI, p = 0.0025) and CHF (OR = 1.620, 95 %, p = 0.016) were associated with VaD with NPS, while a history of emergency department(ED) admission (OR = 0.277, 95 % CI, p = 0.003) likely to be associated with VaD patients without NPS. For AD patients, a history of CVA (OR = 1.395, 95 % CI, p = 0.032) and cancer (OR = 1.485, 95 % CI, p = 0.013) were associated with AD patients with NPS.

DISCUSSION

The findings of this study indicate that an abnormal thyroid gland and CHF were linked to VaD patients with behavioral disturbances, while CVA and cancer were linked to AD patients with behavioral disturbances. These findings suggest the need to develop management strategies for the care of patients with AD and VaD with NPS.

Genetic Complexities of Cerebral Small Vessel Disease, Blood Pressure, and Dementia

Importance

Vascular disease is a treatable contributor to dementia risk, but the role of specific markers remains unclear, making prevention strategies uncertain.

Objective

To investigate the causal association between white matter hyperintensity (WMH) burden, clinical stroke, blood pressure (BP), and dementia risk, while accounting for potential epidemiologic biases.

Design, Setting, and Participants

This study first examined the association of genetically determined WMH burden, stroke, and BP levels with Alzheimer disease (AD) in a 2-sample mendelian randomization (2SMR) framework. Second, using population-based studies (1979-2018) with prospective dementia surveillance, the genetic association of WMH, stroke, and BP with incident all-cause dementia was examined. Data analysis was performed from July 26, 2020, through July 24, 2022.

Exposures

Genetically determined WMH burden and BP levels, as well as genetic liability to stroke derived from genome-wide association studies (GWASs) in European ancestry populations.

Main Outcomes and Measures

The association of genetic instruments for WMH, stroke, and BP with dementia was studied using GWASs of AD (defined clinically and additionally meta-analyzed including both clinically diagnosed AD and AD defined based on parental history [AD-meta]) for 2SMR and incident all-cause dementia for longitudinal analyses.

Results

In 2SMR (summary statistics-based) analyses using AD GWASs with up to 75 024 AD cases (mean [SD] age at AD onset, 75.5 [4.4] years; 56.9% women), larger WMH burden showed evidence for a causal association with increased risk of AD (odds ratio [OR], 1.43; 95% CI, 1.10-1.86; P = .007, per unit increase in WMH risk alleles) and AD-meta (OR, 1.19; 95% CI, 1.06-1.34; P = .008), after accounting for pulse pressure for the former. Blood pressure traits showed evidence for a protective association with AD, with evidence for confounding by shared genetic instruments. In the longitudinal (individual-level data) analyses involving 10 699 incident all-cause dementia cases (mean [SD] age at dementia diagnosis, 74.4 [9.1] years; 55.4% women), no significant association was observed between larger WMH burden and incident all-cause dementia (hazard ratio [HR], 1.02; 95% CI, 1.00-1.04; P = .07). Although all exposures were associated with mortality, with the strongest association observed for systolic BP (HR, 1.04; 95% CI, 1.03-1.06; P = 1.9 × 10-14), there was no evidence for selective survival bias during follow-up using illness-death models. In secondary analyses using polygenic scores, the association of genetic liability to stroke, but not genetically determined WMH, with dementia outcomes was attenuated after adjusting for interim stroke.

Conclusions

These findings suggest that WMH is a primary vascular factor associated with dementia risk, emphasizing its significance in preventive strategies for dementia. Future studies are warranted to examine whether this finding can be generalized to non-European populations.

Integrated Analysis of Chromatin and Transcriptomic Profiling Identifies PU.1 as a Core Regulatory Factor in Microglial Activation Induced by Chronic Cerebral Hypoperfusion

In addition to causing white matter lesions, chronic cerebral hypoperfusion (CCH) can also cause damage to gray matter, but the underlying molecular mechanisms remain largely unknown. In order to obtain a better understanding of the relationship between gene expression and transcriptional regulation alterations, novel upstream regulators could be identified using integration analysis of the transcriptome and epigenetic approaches. Here, a bilateral common carotid artery stenosis (BCAS) model was established for inducing CCH in mice. The spatial cognitive function of mice was evaluated, and changes in cortical microglia morphology were observed. RNA-sequencing (RNA-seq) and the assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) were performed on isolated mouse cortical brain tissue. Then, a systematic joint analysis of BCAS hypoperfusion-induced cortex-specific RNA-seq and ATAC-seq was conducted in order to assess the extent of the correlation between the two, and PU.1 was found to be greatly enriched through motif analysis and transcription factor annotation. Also, the core regulatory factor PU.1 induced by BCAS hypoperfusion was shown to be colocalized with microglia. Based on the above analysis, PU.1 plays a key regulatory role in microglial activation induced by CCH. And the transcriptome and epigenomic data presented in this study can help identify potential targets for future research exploring chronic hypoperfusion-induced brain injury.

The Early Postoperative Course of Cognitive Function and Preoperative Cerebrovascular Reserve

BACKGROUND

 Patients with severe steno-occlusive disease of a main cerebral artery without causative lesions on magnetic resonance imaging (MRI) often develop cognitive impairment. However, the effects of revascularization surgery and the source of the cognitive impairment remain unclear. Therefore, we investigated the early postoperative course of cognitive function and its association with cerebral blood flow (CBF), cerebrovascular reserve (CVR), white matter disease (WMD), lacunar infarction, and cerebrovascular risk factors.

METHODS

 Cognitive function was examined using neurobehavioral cognitive status examination (COGNISTAT) in 52 patients with steno-occlusive disease of a main cerebral artery before and at 6 months after superficial temporal artery-middle cerebral artery (STA-MCA) anastomosis. We examined how cognition changed before and at 1, 3, and 6 months after STA-MCA anastomosis in 27 of 52 patients. CVR and CBF were calculated from 123I-N-isopropyl-p-iodoamphetamine single photon emission computed tomography, in addition to other cerebrovascular risk factors in 34 of 52 patients. Cerebral infarction and WMD (periventricular hyperintensity [PVH] and deep subcortical white matter hyperintensity) were also evaluated preoperatively by MRI.

RESULTS

 COGNISTAT scores improved at 1 month after STA-MCA anastomosis in patients with severe steno-occlusive disease of a main cerebral artery. Multiple stepwise regression analysis revealed that CVR (regression coefficient = -2.237, p = 0.0020) and PVH (regression coefficient = 2.364, p = 0.0029) were the best predictors of postoperative improvement in COGNISTAT scores (R 2 = 0.415; p = 0.0017).

CONCLUSION

 Cognitive function improves in relation to preoperative CVR and PVH early after STA-MCA anastomosis in patients with steno-occlusive disease of a main cerebral artery.

Deciphering mitochondrial dysfunction: Pathophysiological mechanisms in vascular cognitive impairment

Vascular cognitive impairment (VCI) encompasses a range of cognitive deficits arising from vascular pathology. The pathophysiological mechanisms underlying VCI remain incompletely understood; however, chronic cerebral hypoperfusion (CCH) is widely acknowledged as a principal pathological contributor. Mitochondria, crucial for cellular energy production and intracellular signaling, can lead to numerous neurological impairments when dysfunctional. Recent evidence indicates that mitochondrial dysfunction-marked by oxidative stress, disturbed calcium homeostasis, compromised mitophagy, and anomalies in mitochondrial dynamics-plays a pivotal role in VCI pathogenesis. This review offers a detailed examination of the latest insights into mitochondrial dysfunction within the VCI context, focusing on both the origins and consequences of compromised mitochondrial health. It aims to lay a robust scientific groundwork for guiding the development and refinement of mitochondrial-targeted interventions for VCI.

Detection of common pathogenesis of rheumatoid arthritis and atherosclerosis via microarray data analysis

Despite extensive research reveal rheumatoid arthritis (RA) is related to atherosclerosis (AS), common pathogenesis between these two diseases still needs to be explored. In current study, we explored the common pathogenesis between rheumatoid arthritis (RA) and atherosclerosis (AS) by identifying 297 Differentially Expressed Genes (DEGs) associated with both diseases. Through KEGG and GO functional analysis, we highlighted the correlation of these DEGs with crucial biological processes such as the vesicle transport, immune system process, signaling receptor binding, chemokine signaling and many others. Employing Protein-Protein Interaction (PPI) network analysis, we elucidated the associations between DEGs, revealing three gene modules enriched in immune system process, vesicle, signaling receptor binding, Pertussis, and among others. Additionally, through CytoHubba analysis, we pinpointed 11 hub genes integral to intergrin-mediated signaling pathway, plasma membrane, phosphotyrosine binding, chemokine signaling pathway and so on. Further investigation via the TRRUST database identified two key Transcription Factors (TFs), SPI1 and RELA, closely linked with these hub genes, shedding light on their regulatory roles. Finally, leveraging the collective insights from hub genes and TFs, we proposed 10 potential drug candidates targeting the molecular mechanisms underlying RA and AS pathogenesis. Further investigation on xCell revealed that 14 types of cells were all different in both AS and RA. This study underscores the shared pathogenic mechanisms, pivotal genes, and potential therapeutic interventions bridging RA and AS, offering valuable insights for future research and clinical management strategies.

Dementia Development during Long-Term Follow-Up after Surgical Aortic Valve Replacement with a Biological Prosthesis in a Geriatric Population

Surgical aortic valve replacement (SAVR) with a biological heart valve prosthesis (BHV) is often used as a treatment in elderly patients with symptomatic aortic valve disease. This age group is also at risk for the development of dementia in the years following SAVR. The research question is "what are the predictors for the development of dementia?". In 1500 patients undergoing SAVR with or without an associated procedure, preoperative (demographic, cardiac and non-cardiac comorbid conditions), perioperative (associated procedures, cross-clamp and cardiopulmonary bypass time) and postoperative 30-day adverse events (bleeding, thromboembolism, heart failure, conduction defects, arrhythmias, delirium, renal and pulmonary complications) were investigated for their effect on the occurrence of dementia by univariate analyses. Significant factors were entered in a multivariate analysis. The sum of the individual follow-up of the patients was 10,182 patient-years, with a mean follow-up of 6.8 years. Data for the development of dementia could be obtained in 1233 of the 1406 patients who left the hospital alive. Dementia during long-term follow-up developed in 216/1233 (17.2%) of the patients at 70 ± 37 months. Development of dementia reduced the mean survival from 123 (119-128) to 109 (102-116) months (p < 0.001). Postoperative delirium was the dominant predictor (OR = 3.55 with a 95%CI of 2.41-4.93; p < 0.00), followed by age > 80 years (2.38; 1.78-3.18; p < 0.001); preoperative atrial fibrillation (1.47; 1.07-2.01; p = 0.018); cardiopulmonary bypass time > 120 min (1.34; 1.02-1.78; p = 0.039) and postoperative thromboembolism (1.94; 1.02-3.70; p = 0.044). Postoperative delirium, as a marker for poor condition, and an age of 80 or more were the dominant predictors.

Long-range inhibitory neurons mediate cortical neurovascular coupling

To meet the high energy demands of brain function, cerebral blood flow (CBF) parallels changes in neuronal activity by a mechanism known as neurovascular coupling (NVC). However, which neurons play a role in mediating NVC is not well understood. Here, we identify in mice and humans a specific population of cortical GABAergic neurons that co-express neuronal nitric oxide synthase and tachykinin receptor 1 (Tacr1). Through whole-tissue clearing, we demonstrate that Tacr1 neurons extend local and long-range projections across functionally connected cortical areas. We show that whisker stimulation elicited Tacr1 neuron activity in the barrel cortex through feedforward excitatory pathways. Additionally, through optogenetic experiments, we demonstrate that Tacr1 neurons are instrumental in mediating CBF through the relaxation of mural cells in a similar fashion to whisker stimulation. Finally, by electron microscopy, we observe that Tacr1 processes contact astrocytic endfeet. These findings suggest that Tacr1 neurons integrate cortical activity to mediate NVC.

Ion transporter cascade, reactive astrogliosis and cerebrovascular diseases

Cerebrovascular diseases and their sequalae, such as ischemic stroke, chronic cerebral hypoperfusion, and vascular dementia are significant contributors to adult disability and cognitive impairment in the modern world. Astrocytes are an integral part of the neurovascular unit in the CNS and play a pivotal role in CNS homeostasis, including ionic and pH balance, neurotransmission, cerebral blood flow, and metabolism. Astrocytes respond to cerebral insults, inflammation, and diseases through unique molecular, morphological, and functional changes, collectively known as reactive astrogliosis. The function of reactive astrocytes has been a subject of debate. Initially, astrocytes were thought to primarily play a supportive role in maintaining the structure and function of the nervous system. However, recent studies suggest that reactive astrocytes may have both beneficial and detrimental effects. For example, in chronic cerebral hypoperfusion, reactive astrocytes can cause oligodendrocyte death and demyelination. In this review, we will summarize the (1) roles of ion transporter cascade in reactive astrogliosis, (2) role of reactive astrocytes in vascular dementia and related dementias, and (3) potential therapeutic approaches for dementing disorders targeting reactive astrocytes. Understanding the relationship between ion transporter cascade, reactive astrogliosis, and cerebrovascular diseases may reveal mechanisms and targets for the development of therapies for brain diseases associated with reactive astrogliosis.

Fruit and Vegetable Intake and Risk of Disabling Dementia: Japan Public Health Center Disabling Dementia Study

BACKGROUND

Fruits and vegetables contain abundant amounts of antioxidant vitamins such as vitamin C, α-carotene, and β-carotene. Few prospective observational studies have investigated the effects of fruit and vegetable intake on the risk of dementia, and the results are inconsistent.

OBJECTIVES

Our aim was to examine associations between fruit and vegetable intake and the risk of disabling dementia.

METHODS

We conducted a follow-up survey within the Japan Public Health Center-based Prospective Study involving 42,643 individuals aged 50-79 y at baseline (2000-2003). Dietary fruit and vegetable intakes and related antioxidant vitamin intakes (i.e., α-carotene, β-carotene, and vitamin C) were determined using a food frequency questionnaire. The diagnosis of disabling dementia was made based on the daily living disability status related to dementia under the Japanese long-term care insurance program from 2006 to 2016. Hazard ratios and 95% confidence intervals for disabling dementia were estimated using area-stratified Cox proportional hazard models adjusted for potential confounding factors.

RESULTS

A total of 4994 cases of disabling dementia were recorded. We observed an inverse association between total fruit and vegetable intake and the risk of dementia among males and females: the multivariate hazard ratios (95% confidence intervals) for the highest compared with lowest quartiles of intake were 0.87 (0.76, 0.99) (P- trend = 0.05) among males and 0.85 (0.76, 0.94) (P- trend = 0.006) among females. Among antioxidant vitamins, vitamin C intake was inversely associated with the risk of dementia among males and females: the multivariate hazard ratios (95% confidence intervals) for the highest compared with lowest quartiles of intake were 0.71 (0.61, 0.84) (P- trend < 0.0001) among males, and 0.76 (0.67, 0.86) (P- trend < 0.0001) among females.

CONCLUSIONS

Fruit and vegetable intake and dietary intake of vitamin C may contribute to reducing the risk of disabling dementia among males and females.

The role of the Pin1-cis P-tau axis in the development and treatment of vascular contribution to cognitive impairment and dementia and preeclampsia

Tauopathies are neurodegenerative diseases characterized by deposits of abnormal Tau protein in the brain. Conventional tauopathies are often defined by a limited number of Tau epitopes, notably neurofibrillary tangles, but emerging evidence suggests structural heterogeneity among tauopathies. The prolyl isomerase Pin1 isomerizes cis P-tau to inhibit the development of oligomers, tangles and neurodegeneration in multiple neurodegenerative diseases such as Alzheimer's disease, traumatic brain injury, vascular contribution to cognitive impairment and dementia (VCID) and preeclampsia (PE). Thus, cis P-tau has emerged as an early etiological driver, blood marker and therapeutic target for multiple neurodegenerative diseases, with clinical trials ongoing. The discovery of cis P-tau and other tau pathologies in VCID and PE calls attention for simplistic classification of tauopathy in neurodegenerative diseases. These recent advances have revealed the exciting novel role of the Pin1-cis P-tau axis in the development and treatment of vascular contribution to cognitive impairment and dementia and preeclampsia.

Effect of the duration of hypertension on white matter structure and its link with cognition

The relation between hypertension (HTN) and cognition has been reported inclusive results, which may be affected by disease duration. Our study aimed to examine the influence of HTN duration on cognition and its underlying white matter (WM) changes including macrostructural WM hyperintensities (WMH) and microstructural WM integrity. A total of 1218 patients aged ≥55 years with neuropsychological assessment and a subgroup of 233 people with imaging data were recruited and divided into 3 groups (short duration: <5 years, medium duration: 5-20 years, long duration: >20 years). We found that greater HTN duration was preferentially related to worse executive function (EF), processing speed (PS), and more severe WMH, which became more significant during long duration stage. The reductions in WM integrity were evident at the early stage especially in long-range association fibers and then scattered through the whole brain. Increasing WMH and decreasing integrity of specific tracts consistently undermined EF. Furthermore, free water imaging method greatly enhanced the sensitivity in detecting HTN-related WM alterations. These findings supported that the neurological damaging effects of HTN is cumulative and neuroimaging markers of WM at macro- and microstructural level underlie the progressive effect of HTN on cognition.

Developmental priming of early cerebrovascular ageing: Implications across a lifetime

INTRODUCTION

Neurological conditions such as Alzheimer's disease and stroke represent a substantial health burden to the world's ageing population. Cerebrovascular dysfunction is a key contributor to these conditions, affecting an individual's risk profile, age of onset, and severity of neurological disease. Recent data shows that early-life events, such as maternal health during pregnancy, birth weight and exposure to environmental toxins can 'prime' the vascular system for later changes. With age, blood vessels can become less flexible and more prone to damage. This can lead to reduced blood flow to the brain, which is associated with cognitive decline and an increased risk of stroke and other cerebrovascular diseases. These in turn increase the risk of vascular dementia and Alzheimer's disease.

OBJECTIVES

We aim to explore how early life factors influence cerebrovascular health, ageing and disease.

METHODS

We have reviewed recently published literature from epidemiological studies, clinical cases and basic research which explore mechanisms that contribute to cerebrovascular and blood-brain barrier dysfunction, with a particularly focus on those that assess contribution of early-life events or vascular priming to subsequent injury.

RESULTS

Perinatal events have been linked to acute cerebrovascular dysfunction and long-term structural reorganisation. Systemic disease throughout the lifetime that produce inflammatory or oxidative stress may further sensitise the cerebrovasculature to disease and contribute to neurodegeneration.

CONCLUSIONS

By identifying these early-life determinants and understanding their mechanisms, scientists aim to develop strategies for preventing or mitigating cerebrovascular ageing-related issues.

Exercise Improves Cerebral Blood Flow and Functional Outcomes in an Experimental Mouse Model of Vascular Cognitive Impairment and Dementia (VCID)

Vascular cognitive impairment and dementia (VCID) are a growing threat to public health without any known treatment. The bilateral common carotid artery stenosis (BCAS) mouse model is valid for VCID. Previously, we have reported that remote ischemic postconditioning (RIPostC) during chronic cerebral hypoperfusion (CCH) induced by BCAS increases cerebral blood flow (CBF), improves cognitive function, and reduces white matter damage. We hypothesized that physical exercise (EXR) would augment CBF during CCH and prevent cognitive impairment in the BCAS model. BCAS was performed in C57/B6 mice of both sexes to establish CCH. One week after the BCAS surgery, mice were randomized to treadmill exercise once daily or no EXR for four weeks. CBF was monitored with an LSCI pre-, post, and 4 weeks post-BCAS. Cognitive testing was performed for post-BCAS after exercise training, and brain tissue was harvested for histopathology and biochemical test. BCAS led to chronic hypoperfusion resulting in impaired cognitive function and other functional outcomes. Histological examination revealed that BCAS caused changes in neuronal morphology and cell death in the cortex and hippocampus. Immunoblotting showed that BCAS was associated with a significant downregulate of AMPK and pAMPK and NOS3 and pNOS3. BCAS also decreased red blood cell (RBC) deformability. EXR therapy increased and sustained improved CBF and cognitive function, muscular strength, reduced cell death, and loss of white matter. EXR is effective in the BCAS model, improving CBF and cognitive function, reducing white matter damage, improving RBC deformability, and increasing RBC NOS3 and AMPK. The mechanisms by which EXR improves CBF and attenuates tissue damage need further investigation.

Proteomics of mouse brain endothelium uncovers dysregulation of vesicular transport pathways during aging

Age-related decline in brain endothelial cell (BEC) function contributes critically to neurological disease. Comprehensive atlases of the BEC transcriptome have become available, but results from proteomic profiling are lacking. To gain insights into endothelial pathways affected by aging, we developed a magnetic-activated cell sorting-based mouse BEC enrichment protocol compatible with proteomics and resolved the profiles of protein abundance changes during aging. Unsupervised cluster analysis revealed a segregation of age-related protein dynamics with biological functions, including a downregulation of vesicle-mediated transport. We found a dysregulation of key regulators of endocytosis and receptor recycling (most prominently Arf6), macropinocytosis and lysosomal degradation. In gene deletion and overexpression experiments, Arf6 affected endocytosis pathways in endothelial cells. Our approach uncovered changes not picked up by transcriptomic studies, such as accumulation of vesicle cargo and receptor ligands, including Apoe. Proteomic analysis of BECs from Apoe-deficient mice revealed a signature of accelerated aging. Our findings provide a resource for analysing BEC function during aging.

Soluble Biomarkers of Cerebrovascular Pathologies

Vascular contributions to cognitive impairment and dementia (VCID) is an all-encompassing term that describes cognitive impairment due to cerebrovascular origins. With the advancement of imaging and pathological studies, we now understand that VCID is often comorbid with Alzheimer disease. While researchers in the Alzheimer disease field have been working for years to establish and test blood-based biomarkers for Alzheimer disease diagnosis, prognosis, clinical therapy discovery, and early detection, blood-based biomarkers for VCID are in their infancy and also face challenges. VCID is heterogeneous, comprising many different pathological entities (ischemic, or hemorrhagic), and spatial and temporal differences (acute or chronic). This review highlights pathways that are aiding the search for sensitive and specific blood-based cerebrovascular dysfunction markers, describes promising candidates, and explains ongoing initiatives to discover blood-based VCID biomarkers.

Longitudinal changes in diffusion tensor imaging in hemodialysis patients

INTRODUCTION

Hemodialysis patients have increased white matter and gray matter pathology in the brain relative to controls based on MRI. Diffusion tensor imaging is useful in detecting differences between hemodialysis and controls but has not identified the expected longitudinal decline in hemodialysis patients. In this study we implemented specialized post-processing techniques to reduce noise to detect longitudinal changes in diffusion tensor imaging parameters and evaluated for any association with changes in cognition.

METHODS

We collected anatomical and diffusion MRIs as well as cognitive testing from in-center hemodialysis patients at baseline and 1 year later. Gray matter thickness, white matter volume, and white matter diffusion tensor imaging parameters were measured to identify longitudinal changes. We analyzed the diffusion tensor imaging parameters by averaging the whole white matter and using a pothole analysis. Eighteen hemodialysis patients were included in the longitudinal analysis and 15 controls were used for the pothole analysis. We used the NIH Toolbox Cognition Battery to assess cognitive performance over the same time frame.

FINDINGS

Over the course of a year on hemodialysis, we found a decrease in white matter fractional anisotropy across the entire white matter (p < 0.01), and an increase in the number of white matter fractional anisotropy voxels below pothole threshold (p = 0.03). We did not find any relationship between changes in whole brain structural parameters and cognitive performance.

DISCUSSION

By employing noise reducing techniques, we were able to detect longitudinal changes in diffusion tensor imaging parameters in hemodialysis patients. The fractional anisotropy declines over the year indicate significant decreases in white matter health. However, we did not find that declines in fractional anisotropy was associated with declines in cognitive performance.

White matter hyperintensity patterns: associations with comorbidities, amyloid, and cognition

BACKGROUND

White matter hyperintensities (WMHs) are often measured globally, but spatial patterns of WMHs could underlie different risk factors and neuropathological and clinical correlates. We investigated the spatial heterogeneity of WMHs and their association with comorbidities, Alzheimer's disease (AD) risk factors, and cognition.

METHODS

In this cross-sectional study, we studied 171 cognitively unimpaired (CU; median age: 65 years, range: 50 to 89) and 51 mildly cognitively impaired (MCI; median age: 72, range: 53 to 89) individuals with available amyloid (18F-flutementamol) PET and FLAIR-weighted images. Comorbidities were assessed using the Cumulative Illness Rating Scale (CIRS). Each participant's white matter was segmented into 38 parcels, and WMH volume was calculated in each parcel. Correlated principal component analysis was applied to the parceled WMH data to determine patterns of WMH covariation. Adjusted and unadjusted linear regression models were used to investigate associations of component scores with comorbidities and AD-related factors. Using multiple linear regression, we tested whether WMH component scores predicted cognitive performance.

RESULTS

Principal component analysis identified four WMH components that broadly describe FLAIR signal hyperintensities in posterior, periventricular, and deep white matter regions, as well as basal ganglia and thalamic structures. In CU individuals, hypertension was associated with all patterns except the periventricular component. MCI individuals showed more diverse associations. The posterior and deep components were associated with renal disorders, the periventricular component was associated with increased amyloid, and the subcortical gray matter structures was associated with sleep disorders, endocrine/metabolic disorders, and increased amyloid. In the combined sample (CU + MCI), the main effects of WMH components were not associated with cognition but predicted poorer episodic memory performance in the presence of increased amyloid. No interaction between hypertension and the number of comorbidities on component scores was observed.

CONCLUSION

Our study underscores the significance of understanding the regional distribution patterns of WMHs and the valuable insights that risk factors can offer regarding their underlying causes. Moreover, patterns of hyperintensities in periventricular regions and deep gray matter structures may have more pronounced cognitive implications, especially when amyloid pathology is also present.

The Role of NRF2 in Cerebrovascular Protection: Implications for Vascular Cognitive Impairment and Dementia (VCID)

Vascular cognitive impairment and dementia (VCID) represents a broad spectrum of cognitive decline secondary to cerebral vascular aging and injury. It is the second most common type of dementia, and the prevalence continues to increase. Nuclear factor erythroid 2-related factor 2 (NRF2) is enriched in the cerebral vasculature and has diverse roles in metabolic balance, mitochondrial stabilization, redox balance, and anti-inflammation. In this review, we first briefly introduce cerebrovascular aging in VCID and the NRF2 pathway. We then extensively discuss the effects of NRF2 activation in cerebrovascular components such as endothelial cells, vascular smooth muscle cells, pericytes, and perivascular macrophages. Finally, we summarize the clinical potential of NRF2 activators in VCID.

Oxygen imaging of hypoxic pockets in the mouse cerebral cortex

Consciousness is lost within seconds upon cessation of cerebral blood flow. The brain cannot store oxygen, and interruption of oxidative phosphorylation is fatal within minutes. Yet only rudimentary knowledge exists regarding cortical partial oxygen tension (Po2) dynamics under physiological conditions. Here we introduce Green enhanced Nano-lantern (GeNL), a genetically encoded bioluminescent oxygen indicator for Po2 imaging. In awake behaving mice, we uncover the existence of spontaneous, spatially defined "hypoxic pockets" and demonstrate their linkage to the abrogation of local capillary flow. Exercise reduced the burden of hypoxic pockets by 52% compared with rest. The study provides insight into cortical oxygen dynamics in awake behaving animals and concurrently establishes a tool to delineate the importance of oxygen tension in physiological processes and neurological diseases.

Experimental Ischemic Stroke Induces Secondary Bihemispheric White Matter Degeneration and Long-Term Cognitive Impairment

Clinical studies have identified widespread white matter degeneration in ischemic stroke patients. However, contemporary research in stroke has predominately focused on the infarct and periinfarct penumbra regions. The involvement of white matter degeneration after ischemic stroke and its contribution to post-stroke cognitive impairment and dementia (PSCID) has remained less explored in experimental models. In this study, we examined the progression of locomotor and cognitive function up to 4 months after inducing ischemic stroke by middle cerebral artery occlusion in young adult rats. Despite evident ongoing locomotor recovery, long-term cognitive and affective impairments persisted after ischemic stroke, as indicated by Morris water maze, elevated plus maze, and open field performance. At 4 months after stroke, multimodal MRI was conducted to assess white matter degeneration. T2-weighted MRI (T2WI) unveiled bilateral cerebroventricular enlargement after ischemic stroke. Fluid Attenuated Inversion Recovery MRI (FLAIR) revealed white matter hyperintensities in the corpus callosum and fornix across bilateral hemispheres. A positive association between the volume of white matter hyperintensities and total cerebroventricular volume was noted in stroke rats. Further evidence of bilateral white matter degeneration was indicated by the reduction of fractional anisotropy and quantitative anisotropy at bilateral corpus callosum in diffusion-weighted MRI (DWI) analysis. Additionally, microglia and astrocyte activation were identified in the bilateral corpus callosum after stroke. Our study suggests that experimental ischemic stroke induced by MCAO in young rat replicate long-term cognitive impairment and bihemispheric white matter degeneration observed in ischemic stroke patients. This model provides an invaluable tool for unraveling the mechanisms underlying post-stroke secondary white matter degeneration and its contribution to PSCID.

Hypertension: Causes and Consequences of Circadian Rhythms in Blood Pressure

Hypertension is extremely common, affecting approximately 1 in every 2 adults globally. Chronic hypertension is the leading modifiable risk factor for cardiovascular disease and premature mortality worldwide. Despite considerable efforts to define mechanisms that underlie hypertension, a potentially major component of the disease, the role of circadian biology has been relatively overlooked in both preclinical models and humans. Although the presence of daily and circadian patterns has been observed from the level of the genome to the whole organism, the functional and structural impact of biological rhythms, including mechanisms such as circadian misalignment, remains relatively poorly defined. Here, we review the impact of daily rhythms and circadian systems in regulating blood pressure and the onset, progression, and consequences of hypertension. There is an emphasis on the impact of circadian biology in relation to vascular disease and end-organ effects that, individually or in combination, contribute to complex phenotypes such as cognitive decline and the loss of cardiac and brain health. Despite effective treatment options for some individuals, control of blood pressure remains inadequate in a substantial portion of the hypertensive population. Greater insight into circadian biology may form a foundation for novel and more widely effective molecular therapies or interventions to help in the prevention, treatment, and management of hypertension and its related pathophysiology.

Specific knockout of macrophage SHP2 promotes macrophage M2 polarization and alleviates renal ischemia-reperfusion injury

To investigate the effect of specific knockout of SHP2 in mononuclear macrophages on renal ischemia-reperfusion injury and its molecular mechanism. The structural, functional, and pathological changes in the mouse kidney were detected by ultrasound testing. The relative fluorescence intensity of α-SMA, Col1, Col3, and Vim was measured by immunofluorescence staining, and ELISA was performed to detect the concentrations of blood urea nitrogen (BUN), creatinine (Crea), and uric acid (UA). The relative protein expressions of relevant proteins in the mouse kidney tissue were detected by western blotting. Specific knockout of SHP2 could improve both renal function and structure, reduce the relative fluorescence intensity of α-SMA, Col1, Col3 and Vim, lower the concentrations of BUN, Crea, and UA and the expressions of TNF-α, IFNγ, p-NFκB, and p-MyD88, and increase the expressions of p-MerTK, p-FAK, p-PI3K, and p-IκB. The above results illustrate that specific knockdown of macrophage SHP2 promotes macrophage M2 polarization and alleviates renal ischemia-reperfusion injury. The above results illustrate that specific knockdown of macrophage SHP2 promotes macrophage M2 polarization and attenuatesll renal ischemia-reperfusion injury. Specific knockout of macrophage SHP2 promotes macrophage M2 polarization and alleviates renal ischemia-reperfusion injury.

Pulsatility analysis of the circle of Willis

Purpose

To evaluate the phenomenological significance of cerebral blood pulsatility imaging in aging research.

Methods

N = 38 subjects from 20 to 72 years of age (24 females) were imaged with ultrafast MRI with a sampling rate of 100 ms and simultaneous acquisition of pulse oximetry data. Of these, 28 subjects had acceptable MRI and pulse data, with 16 subjects between 20 and 28 years of age, and 12 subjects between 61 and 72 years of age. Pulse amplitude in the circle of Willis was assessed with the recently developed method of analytic phase projection to extract blood volume waveforms.

Results

Arteries in the circle of Willis showed pulsatility in the MRI for both the young and old age groups. Pulse amplitude in the circle of Willis significantly increased with age (p = 0.01) but was independent of gender, heart rate, and head motion during MRI.

Discussion and conclusion

Increased pulse wave amplitude in the circle of Willis in the elderly suggests a phenomenological significance of cerebral blood pulsatility imaging in aging research. The physiologic origin of increased pulse amplitude (increased pulse pressure vs. change in arterial morphology vs. re-shaping of pulse waveforms caused by the heart, and possible interaction with cerebrospinal fluid pulsatility) requires further investigation.

Association evaluations of oral anticoagulants with dementia risk based on genomic and real-world data

BACKGROUND

Several observational studies have suggested that oral anticoagulants (OACs) might reduce the risk of dementia in the elderly, but the evidence is inconclusive. And the consistency of this relationship across different OAC classes and dementia subtypes is still uncertain.

METHODS

To comprehensively evaluate this association, we applied Mendelian randomization (MR) combined with pharmacovigilance analysis. MR was used to assess the associations between genetic proxies for three target genes of OACs (VKORC1, F2, and F10) and dementia, including Alzheimer's disease (AD) and vascular dementia (VaD). This genetic analysis was supplemented with real-world pharmacovigilance data, employing disproportionality analysis for more reliable causal inference.

RESULTS

Increased expression of the VKORC1 gene was strongly associated with increased risk of dementia, especially for AD (OR = 1.28, 95% CI = 1.14-1.43; p value < 0.001). Based on pharmacovigilance data, vitamin K antagonists (VKAs, inhibitors targeting VKORC1) exhibited a protective effect against dementia risk (ROR = 0.43, 95% CI = 0.28-0.67). Additional sensitivity analyses, including different MR models and cohorts, supported these results. Conversely, no strong causal associations of genetically proxied F2 and F10 target genes with dementia and its subtypes were found.

CONCLUSIONS

This study reveals that the inhibition of genetically proxied VKORC1 expression or VKAs exposure is associated with a reduced risk of Alzheimer's dementia. However, there is little evidence to support similar associations with direct oral anticoagulants (F2 inhibitors and F10 inhibitors). Further research is warranted to clinically validate our findings.

SPAK inhibitor ZT-1a attenuates reactive astrogliosis and oligodendrocyte degeneration in a mouse model of vascular dementia

BACKGROUND

Astrogliosis and white matter lesions (WML) are key characteristics of vascular contributions to cognitive impairment and dementia (VCID). However, the molecular mechanisms underlying VCID remain poorly understood. Stimulation of Na-K-Cl cotransport 1 (NKCC1) and its upstream kinases WNK (with no lysine) and SPAK (the STE20/SPS1-related proline/alanine-rich kinase) play a role in astrocytic intracellular Na+ overload, hypertrophy, and swelling. Therefore, in this study, we assessed the effect of SPAK inhibitor ZT-1a on pathogenesis and cognitive function in a mouse model of VCID induced by bilateral carotid artery stenosis (BCAS).

METHODS

Following sham or BCAS surgery, mice were randomly assigned to receive either vehicle (DMSO) or SPAK inhibitor ZT-1a treatment regimen (days 14-35 post-surgery). Mice were then evaluated for cognitive functions by Morris water maze, WML by ex vivo MRI-DTI analysis, and astrogliosis/demyelination by immunofluorescence and immunoblotting.

RESULTS

Compared to sham control mice, BCAS-Veh mice exhibited chronic cerebral hypoperfusion and memory impairments, accompanied by significant MRI DTI-detected WML and oligodendrocyte (OL) death. Increased activation of WNK-SPAK-NKCC1-signaling proteins was detected in white matter tissues and in C3d+ GFAP+ cytotoxic astrocytes but not in S100A10+ GFAP+ homeostatic astrocytes in BCAS-Veh mice. In contrast, ZT-1a-treated BCAS mice displayed reduced expression and phosphorylation of NKCC1, decreased astrogliosis, OL death, and WML, along with improved memory functions.

CONCLUSION

BCAS-induced upregulation of WNK-SPAK-NKCC1 signaling contributes to white matter-reactive astrogliosis, OL death, and memory impairment. Pharmacological inhibition of the SPAK activity has therapeutic potential for alleviating pathogenesis and memory impairment in VCID.

Impact of arterial stiffness on cerebrovascular function: a review of evidence from humans and preclincal models

With advancing age, the cerebral vasculature becomes dysfunctional, and this dysfunction is associated with cognitive decline. However, the initiating cause of these age-related cerebrovascular impairments remains incompletely understood. A characteristic feature of the aging vasculature is the increase in stiffness of the large elastic arteries. This increase in arterial stiffness is associated with elevated pulse pressure and blood flow pulsatility in the cerebral vasculature. Evidence from both humans and rodents supports that increases in large elastic artery stiffness are associated with cerebrovascular impairments. These impacts on cerebrovascular function are wide-ranging and include reductions in global and regional cerebral blood flow, cerebral small vessel disease, endothelial cell dysfunction, and impaired perivascular clearance. Furthermore, recent findings suggest that the relationship between arterial stiffness and cerebrovascular function may be influenced by genetics, specifically APOE and NOTCH genotypes. Given the strength of the evidence that age-related increases in arterial stiffness have deleterious impacts on the brain, interventions that target arterial stiffness are needed. The purpose of this review is to summarize the evidence from human and rodent studies, supporting the role of increased arterial stiffness in age-related cerebrovascular impairments.

The role of gut microbiota in cerebrovascular disease and related dementia

In recent years, increasing evidence suggests that commensal microbiota may play an important role not only in health but also in disease including cerebrovascular disease. Gut microbes impact physiology, at least in part, by metabolizing dietary factors and host-derived substrates and then generating active compounds including toxins. The purpose of this current review is to highlight the complex interplay between microbiota, their metabolites. and essential functions for human health, ranging from regulation of the metabolism and the immune system to modulation of brain development and function. We discuss the role of gut dysbiosis in cerebrovascular disease, specifically in acute and chronic stroke phases, and the possible implication of intestinal microbiota in post-stroke cognitive impairment and dementia, and we identify potential therapeutic opportunities of targeting microbiota in this context. LINKED ARTICLES: This article is part of a themed issue From Alzheimer's Disease to Vascular Dementia: Different Roads Leading to Cognitive Decline. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v181.6/issuetoc.

Xinshubao tablet rescues cognitive dysfunction in a mouse model of vascular dementia: Involvement of neurogenesis and neuroinflammation

Vascular dementia (VaD) represents a severe cognitive dysfunction syndrome closed linked to cardiovascular function. In the present study, we assessed the potential of Xinshubao tablet (XSB), a traditional Chinese prescription widely used for cardiovascular diseases, to mitigate neuropathological damage in a mouse model of VaD and elucidated the underlying mechanisms. Our findings revealed that oral administration of XSB rescued the cardiac dysfunction resulting from bilateral common carotid artery stenosis (BCAS), improved the cerebral blood flow (CBF) and cognitive function, reduced white matter injury, inhibited excessive microglial and astrocytic activation, stimulated hippocampal neurogenesis, and reduced neural apoptosis in the brains of BCAS mice. Mechanistically, RNA-seq analysis indicated that XSB treatment was significantly associated with neuroinflammation, vasculature development, and synaptic transmission, which were further confirmed by q-PCR assays. Western blot results revealed that XSB treatment hindered the nuclear translocation of nuclear factor-κB (NF-κB), thereby suppressing the NF-κB signaling pathway. These results collectively demonstrated that XSB could ameliorate cognitive dysfunction caused by BCAS through regulating CBF, reducing white matter lesions, suppressing glial activation, promoting neurogenesis, and mitigating neuroinflammation. Notably, the NF-κB signaling pathway emerged as a pivotal player in this mechanism.

The crosstalk between epilepsy and dementia: A systematic review and meta-analysis

BACKGROUND

Epilepsy and dementia are bidirectional. The purpose of this review was to investigate the epidemiological characteristics of and to identify the risk factors for epilepsy in patients with dementia and dementia in patients with epilepsy.

METHODS

We retrieved the PubMed, Embase, Cochrane and Web of Science databases through January 2023. Two individuals screened the articles, extracted the data, and used a random effects model to pool the estimates and 95% confidence intervals (CIs).

RESULTS

From 3475 citations, 25 articles were included. The prevalence of seizures/epilepsy was 4% among dementia patients and 3% among Alzheimer's disease (AD) patients. For vascular dementia, Lewy body dementia, and frontotemporal dementia, the pooled period prevalence of seizures/epilepsy was 6%, 3%, and 2%, respectively. Baseline early-onset AD was associated with the highest risk of 5-year epilepsy (pooled hazard ratios: 4.06; 95% CI: 3.25-5.08). Dementia patients had a 2.29-fold greater risk of seizures/epilepsy than non-dementia patients (95% CI: 1.37-3.83). Moreover, for baseline epilepsy, the pooled prevalence of dementia was 17% (95% CI: 10-25%), and that of AD was 15% (95% CI: 9-21%). The pooled results suggested that epilepsy is associated with a greater risk of dementia (risk ratio: 2.83, 95% CI: 1.64-4.88).

CONCLUSIONS

There are still gaps in epidemiology regarding the correlation between dementia types and epilepsy, vascular risk factors, and the impact of antiseizure medication or cognitive improvement drugs on epilepsy and AD comorbidity.

Effects of folic acid supplementation on cognitive impairment: A meta-analysis of randomized controlled trials

OBJECTIVE

With the increasing number of patients with cognitive impairment, nonpharmacological ways to delay cognitive impairment have attracted people's attention, such as lifestyle changes and nutritional supplementation. Folic acid supplementation appears to be a promising treatment option. However, it remains controversial whether folic acid supplementation is effective in delaying adult's cognitive impairment. Therefore, we conducted a meta-analysis to analyze the effects of folic acid supplementation on different cognitive impairments.

METHODS

We systematically searched PubMed, Web of Science, EMbase, Cochrane Central Register of Controlled Trials, China National Knowledge Infrastructure (CNKI), WanFang and VIP databases for randomized controlled trials on January 22, 2024. The included population comprised those diagnosed with cognitive impairment. We included trials that compared folic acid treatment with placebo, other dosing regimens, or other intervention controls. Conducting quality evaluation of included studies according to the Cochrane Risk of Bias tool. Statistical analyses were performed using Review Manager software.

RESULTS

Twenty-two trials, including 3604 participants, met inclusion criteria. Compared with controls, the cognitive function of Alzheimer's disease (AD) patients showed improvement with folic acid supplementation: supplementation with < 3 mg (standardized mean differences (SMD) = 0.15, 95% confidence interval (CI) -0.10 to 0.41), and supplementing with ≥ 3 mg folic acid could improve cognitive function in AD patients (SMD = 1.03, 95% CI 0.18 to 1.88). Additionally, it reduced homocysteine (HCY) levels (mean differences (MD) = -4.74, 95% CI -8.08 to -1.39). In mild cognitive impairment (MCI) patients, cognitive function improved with folic acid supplementation: supplementation with > 400 μg (SMD = 0.38, 95% CI 0.13 to 0.63), and supplementation with ≤ 400 μg (SMD = 1.10, 95% CI 0.88 to 1.31). It also reduced HCY levels at intervention ≤ 6 months (MD = -3.93, 95% CI -5.05 to -2.82) and intervention > 6 months (MD = -4.38, 95% CI -5.15 to -3.61). However, supplementing with folic acid did not improve cognitive function in vascular cognitive impairment (VCI) patients, with folic acid supplements < 3 mg (SMD = -0.07, 95% CI -0.23 to -0.08), folic acid supplements ≥ 3 mg (SMD = 0.46, 95% CI -0.57 to 1.49), however, it reduced HCY levels at intervention > 6 months (MD = -5.91, 95% CI -7.13 to -4.69) and intervention ≤ 6 months (MD = -11.15, 95% CI -12.35 to -9.95).

CONCLUSIONS

Supplement folic acid is beneficial to the cognitive profile of patients with MCI, supplementation with ≥ 3 mg folic acid can improve cognitive function in AD patients.