Chronic cerebral hypoperfusion: An undefined, relevant entity

Deep learning-based magnetic resonance imaging analysis for chronic cerebral hypoperfusion risk

BACKGROUND

Chronic cerebral hypoperfusion (CCH) is a frequently encountered clinical condition that poses a diagnostic challenge due to its nonspecific symptoms.

PURPOSE

To enhance the diagnosis of CCH and non-CCH through Magnetic Resonance Imaging (MRI), offering support in clinical decision-making and recommendations to ultimately elevate diagnostic accuracy and optimize patient treatment outcomes.

METHODS

In the retrospective research, we collected 204 routine brain magnetic resonance imaging (MRI) from March 1 to September 10 2022, as training and testing cohorts. And a validation cohort with 108 samples was collected from November 14 2022 to August 4 2023. MRI sequences were processed to obtain T1-weighted (T1WI) and T2-weighted (T2WI) sequence images for each patient. We propose CCH-Network (CCHNet), an end-to-end deep learning model, integrating convolution and Transformer modules to capture local and global structural information. Our novel adversarial training method improves feature knowledge capture, enhancing both generalization ability and efficiency in predicting CCH risk. We assessed the classification performance of the proposed model CCHNet by comparing it with existing state-of-the-art deep learning algorithms, including ResNet34, DenseNet121, VGG16, Convnext, ViT, Coat, and TransFG. To better validate model performance, we compared the results of the proposed model with eight neurologists to evaluate their consistency.

RESULTS

CCHNet achieved an AUC of 91.6% (95% CI: 86.8-99.1), with an accuracy (ACC) of 85.0% (95% CI: 75.6-95.2). It demonstrated a sensitivity (SE) of 80.0% (95% CI: 71.6-95.6) and a specificity (SP) of 90.0% (95% CI: 82.3-97.8) in the testing cohort. In the validation cohort, the model demonstrated an AUC of 86.0% (95% CI: 80.3-93.0), an ACC of 84.2% (95% CI: 70.2-93.6), a SE of 83.3% (95% CI: 68.3-95.5), and a SP of 84.7% (95% CI: 70.3-96.8).

CONCLUSIONS

The model improved the diagnostic performance of MRI with high SE and SP, providing a promising method for the diagnosis of CCH.

Cerebral hypoperfusion exacerbates traumatic brain injury in male but not female mice

Mild-moderate traumatic brain injuries (TBIs) are prevalent, and while many individuals recover, there is evidence that a significant number experience long-term health impacts, including increased vulnerability to neurodegenerative diseases. These effects are influenced by other risk factors, such as cardiovascular disease. Our study tested the hypothesis that a pre-injury reduction in cerebral blood flow (CBF), mimicking cardiovascular disease, worsens TBI recovery. We induced bilateral carotid artery stenosis (BCAS) and a mild-moderate closed-head TBI in male and female mice, either alone or in combination, and analyzed CBF, spatial learning, memory, axonal damage, and gene expression. Findings showed that BCAS and TBI independently caused a ~10% decrease in CBF. Mice subjected to both BCAS and TBI experienced more significant CBF reductions, notably affecting spatial learning and memory, particularly in males. Additionally, male mice showed increased axonal damage with both BCAS and TBI compared to either condition alone. Females exhibited spatial memory deficits due to BCAS, but these were not worsened by subsequent TBI. Gene expression analysis in male mice highlighted that TBI and BCAS individually altered neuronal and glial profiles. However, the combination of BCAS and TBI resulted in markedly different transcriptional patterns. Our results suggest that mild cerebrovascular impairments, serving as a stand-in for preexisting cardiovascular conditions, can significantly worsen TBI outcomes in males. This highlights the potential for mild comorbidities to modify TBI outcomes and increase the risk of secondary diseases.

Peripheral blood diagnostic markers of chronic cerebral hypoperfusion

OBJECTIVE

To investigate the efficacy of ischemia-modified albumin (IMA), lipoprotein-associated phospholipase A2 (Lp-PLA2), brain-derived neurotrophic factor (BDNF), and visinin-like protein-1 (VILIP-1) in diagnosing chronic cerebral hypoperfusion (CCH).

METHODS

This retrospective study included 84 patients with suspected chronic cerebral ischemia admitted to Sichuan Provincial People's Hospital between February 2021 and April 2022. Arterial spin labeling (ASL) imaging and biological examinations were performed. According to the ASL perfusion imaging patterns, the patients were divided into a CCH group (n = 55) and a non-CCH group (n = 29). Serum markers of the two groups were compared, and correlation analysis was conducted between ischemic marker levels and cerebral blood flow (CBF) in the ischemic region, as measured by ASL. Receiver operating characteristic (ROC) curve analysis was used to evaluate the efficacy of each marker for diagnosing chronic cerebral ischemia. The Delong test was used to compare AUC size between groups.

RESULTS

Compared to the non-CCH group, the CCH group exhibited higher IMA levels and lower BDNF concentrations (P < 0.05). However, VILIP-1 and Lp-PLA2 concentrations were not significantly different between the two groups (P > 0.05). Moreover, IMA and BDNF levels were not correlated with CBF in the hypoperfused area. ROC curve analysis demonstrated that the cut-off values of 24.2915 U/mL and 6.714 ng/L for IMA and BDNF achieved a sensitivity of 83.6% and 41.8% and a specificity of 62.1% and 93.1%, respectively. Lastly, the areas under the curve for IMA and BDNF were 0.738 (95% confidence interval [CI], 0.627-0.848) and 0.631 (95% CI, 0.512-0.751), respectively.

CONCLUSION

IMA and BDNF may have clinical value in the diagnosis of CCH.

Hexahydrocurcumin Attenuates Neuronal Injury and Modulates Synaptic Plasticity in Chronic Cerebral Hypoperfusion in Rats

Dementia is the most common age-related problem due predominantly to Alzheimer's disease (AD) and vascular dementia (VaD). It has been shown that these contributors are associated with a high amount of oxidative stress that leads to changes in neurological function and cognitive impairment. The aim of study was to explore the mechanism by which hexahydrocurcumin (HHC) attenuates oxidative stress, amyloidogenesis, phosphorylated Tau (pTau) expression, neuron synaptic function, and cognitive impairment and also the potential mechanisms involved in induced permanent occlusion of bilateral common carotid arteries occlusion (BCCAO) or 2-vessel occlusion (2VO) in rats. After surgery, rats were treated with HHC (40 mg/kg) or piracetam (600 mg/kg) by oral gavage daily for 4 weeks. The results showed that HHC or piracetam attenuated oxidative stress by promoting nuclear factor erythroid 2-related factor 2 (Nrf2) activity, and alleviated expression of synaptic proteins (pre- and post-synaptic proteins) mediated by the Wingless/Integrated (Wnt)/β-catenin signaling pathway. Moreover, HHC or piracetam also improved synaptic plasticity via the brain-derived neurotrophic factor (BDNF)/Tyrosine receptor kinase B (TrkB)/cAMP responsive element binding protein (CREB) signaling pathway. In addition, HHC reduced amyloid beta (Aβ) production and pTau expression and improved memory impairment as evidenced by the Morris water maze. In conclusion, HHC exerted remarkable improvement in cognitive function in the 2VO rats possibly via the attenuation of oxidative stress, improvement in synaptic function, attenuation of amyloidogenesis, pTau, and neuronal injury, thereby improving cognitive performance.

Predicting postoperative delirium after percutaneous transluminal angioplasty and stenting in patients with intracranial atherosclerotic stenosis

OBJECTIVE

Known as a major surgical complication, postoperative delirium (POD) has not been well studied in patients with intracranial atherosclerotic stenosis (ICAS). This study aimed to investigate the correlation between perioperative clinical characteristics and the occurrence of POD.

METHODS

Patients' demographic characteristics and perioperative testing data were collected. Binary logistic regression was conducted for assessing related risk factors. A nomogram was developed to predict the occurrence of POD after percutaneous transluminal angioplasty and stenting (PTAS) in patients with ICAS.

RESULTS

The occurrence of POD in this study was 30.67%. Among all the clinical and laboratory characteristics in patients, age (OR = 1.234, 95%CI = 1.004-1.517, p = 0.046), gender (OR = 5.676, 95%CI = 1.028-31.334, p = 0.046), preoperative MMSE scores (OR = 2.298, 95%CI = 1.005-5.259, p = 0.049), the degree of stenosis (OR = 6.294, 95%CI = 1.043-37.974, p = 0.045), operating time (OR = 1.088, 95%CI = 1.023-1.157, p = 0.006), and HbA1c levels (OR = 2.226, 95%CI = 1.199-4.130, p = 0.011) were the independent risk factors.

CONCLUSION

Male patients with advanced-age, lower preoperative MMSE scores, severe stenosis, longer operating time, and higher HbA1c levels are closely related to POD after PTAS. Fully perioperative assessments may play an important role in predicting the occurrence of POD.

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.

Alleviating CB2-Dependent ER Stress and Mitochondrial Dysfunction Improves Chronic Cerebral Hypoperfusion-Induced Cognitive Impairment

Augmentation of endoplasmic reticulum (ER) stress may trigger excessive oxidative stress, which induces mitochondrial dysfunction. The fatty acid amide hydrolase inhibitor, URB597, shows anti-oxidation characteristics in multiple neurological disorders. The present study aimed to determine whether inhibition of ER stress was involved in the protective effects of URB597 against chronic cerebral hypoperfusion (CCH)-induced cognitive impairment. Hippocampal HT-22 cells were exposed to oxygen-glucose deprivation. The cell viability, apoptosis, ER stress, mitochondrial ATP, and oxidative stress levels were assessed following treatment with URB597, benzenebutyric acid (4-PBA), and thapsigargin (TG). Furthermore, the effects of URB597 on ER stress and related pathways were investigated in the CCH animal model, including Morris water maze testing of cognition, western blotting analysis of ER stress signaling, and transmission electron microscopy of mitochondrial and ER ultrastructure changes. The results suggested that cerebral ischemia caused ER stress with upregulation of ER stress signaling-related proteins, mitochondrial dysfunction, neuronal apoptosis, ultrastructural injuries of mitochondria-associated ER membranes, and cognitive decline. Co-immunoprecipitation experiments confirmed the interaction between CB2 and β-Arrestin1. Inhibiting ER stress by URB597 improved these changes by activating CB2/β-Arrestin1 signaling, which was reversed by the CB2 antagonist, AM630. Together, the results identified a novel mechanism of URB597, involving CCH-induced cognitive impairment alleviation of CB2-dependent ER stress and mitochondrial dysfunction. Furthermore, this study identified CB2 as a potential target for therapy of ischemic cerebrovascular diseases.

Effect of 40 Hz light flicker on cognitive impairment and transcriptome of hippocampus in right unilateral common carotid artery occlusion mice

Vascular cognitive impairment caused by chronic cerebral hypoperfusion (CCH) seriously affects the quality of life of elderly patients. However, there is no effective treatment to control this disease. This study investigated the potential neuroprotective effect of the 40 Hz light flicker in a mouse model of CCH. CCH was induced in male C57 mice by right unilateral common carotid artery occlusion (rUCCAO), leading to chronic brain injury. The mice underwent 40 Hz light flicker stimulation for 30 days after surgery. The results showed that 40 Hz light flicker treatment ameliorated memory deficits after rUCCAO and alleviated the damage to neurons in the frontal lobe and hippocampus. Light flicker administration at 40 Hz decreased IL-1β and TNF-α levels in the frontal lobe and hippocampus, but immunohistochemistry showed that it did not induce angiogenesis in mice with rUCCAO. Gene expression profiling revealed that the induction of genes was mainly enriched in inflammatory-related pathways. Our findings demonstrate that 40 Hz light flicker can suppress cognitive impairment caused by rUCCAO and that this effect may be involved in the attenuation of neuroinflammation.

Arterial spin labeling perfusion in acute Wernicke encephalopathy: a case series discussion

Wernicke's encephalopathy (WE) is a life-threatening neurologic disorder resulting from thiamine (vitamin B1) deficiency that can be secondary to chronic alcohol abuse, gastrointestinal surgery, systemic infectious and non-infectious diseases, and chemotherapy. WE is classically characterized on MRI by reduced diffusion and T2 prolongation along the mammillothalamic tracts, periaqueductal gray and tectal plate. We present two patients with acute WE who had baseline arterial spin labeling (ASL) perfusion at the time of presentation, demonstrating increase in cerebral blood flow (CBF) within the classically involved brain regions and concurrent global cerebral cortical hypoperfusion. Both patients were successfully treated with intravenous thiamine infusion. Post-treatment MRI demonstrated improvement of reduced diffusion and normalization of CBF within the involved structures. Prior histopathological studies have documented prominent undulation and luminal dilatation of arteries and arterioles in acute WE lesions, likely explaining the increased perfusion shown by imaging. The root of this pathophysiologic process may trace back to thiamine's biochemical role in maintaining osmotic gradients and glucose metabolism, that if failed can lead to arterial hyper-perfusion. Our findings show that ASL-CBF can highlight the underlying pathophysiology in patients with acute WE by demonstrating increased CBF in involved central structures. This luxury perfusion may be a compensatory or protective mechanism by which increased metabolic demand is met in the acute setting and which, if treated timely, will show normalization of CBF on ASL imaging.

VEGF-A ameliorates ischemia hippocampal neural injury via regulating autophagy and Akt/CREB signaling in a rat model of chronic cerebral hypoperfusion

OBJECTIVE

Chronic cerebral hypoperfusion (CCH) can cause a series of pathophysiological processes, including neuronal autophagy and apoptosis. VEGF-A has been reported to affect angiogenesis and neurogenesis in many CNS diseases. However, its effects on neuronal autophagy and apoptosis, as well as the underlying mechanisms in CCH remain unclear.

METHODS

To address these issues, the CCH model was established by permanent bilateral common carotid artery occlusion (2VO). Rats were sacrificed at different stages of CCH. Hippocampal morphological and ultrastructural changes were detected using HE staining and electron microscopy. The immunoreactivities of microtubule-associated protein 1 light chain 3 (LC3) and phospho-cAMP response element binding protein (p-CREB) were examined by immunofluorescence staining. The neuronal apoptosis was detected via TUNEL staining. The levels of LC3-II, Beclin-1, Akt, p-Akt, CREB, p-CREB, Caspase-3, and Bad were accessed by Western blotting. Furthermore, mouse hippocampal HT22 neurons received the oxygen and glucose deprivation (OGD) treatment, VEGF-A treatment, and GSK690693 (an Akt inhibitor) treatment, respectively.

RESULTS

LC3-II protein started to increase at 3 days of CCH, peaked at 4 weeks of CCH, then decreased. CCH increased the levels of LC3-II, Caspase-3, and Bad, and decreased the levels of p-Akt, CREB, and p-CREB, which were reversed by VEGF-A treatment. VEGF-A also improved CCH-induced neuronal ultrastructural injuries and apoptosis in the hippocampus in vitro. In HT22, the anti-apoptosis and pro-phosphorylation of VEGF-A were reversed by GSK690693.

CONCLUSION

Present results provide a novel neuroprotective effect of VEGF-A in CCH that is related to the inhibition of neuronal autophagy and activation of the Akt/CREB signaling, suggesting a potential therapeutic strategy for ischemic brain damage.

Stronger influence of systemic than local hemodynamic-vascular factors on resting-state BOLD functional connectivity

Correlated fluctuations in the blood oxygenation level dependent (BOLD) signal of resting-state functional MRI (i.e., BOLD-functional connectivity, BOLD-FC) reflect a spectrum of neuronal and non-neuronal processes. In particular, there are multiple hemodynamic-vascular influences on BOLD-FC on both systemic (e.g., perfusion delay) and local levels (e.g., neurovascular coupling). While the influence of individual factors has been studied extensively, combined and comparative studies of systemic and local hemodynamic-vascular factors on BOLD-FC are scarce, notably in humans. We employed a multi-modal MRI approach to investigate and compare distinct hemodynamic-vascular processes and their impact on homotopic BOLD-FC in healthy controls and patients with unilateral asymptomatic internal carotid artery stenosis (ICAS). Asymptomatic ICAS is a cerebrovascular disorder, in which neuronal functioning is largely preserved but hemodynamic-vascular processes are impaired, mostly on the side of stenosis. Investigated indicators for local hemodynamic-vascular processes comprise capillary transit time heterogeneity (CTH) and cerebral blood volume (CBV) from dynamic susceptibility contrast (DSC) MRI, and cerebral blood flow (CBF) from pseudo-continuous arterial spin labeling (pCASL). Indicators for systemic processes are time-to-peak (TTP) from DSC MRI and BOLD lags from functional MRI. For each of these parameters, their influence on BOLD-FC was estimated by a comprehensive linear mixed model. Equally across groups, we found that individual mean BOLD-FC, local (CTH, CBV, and CBF) and systemic (TTP and BOLD lag) hemodynamic-vascular factors together explain 40.7% of BOLD-FC variance, with 20% of BOLD-FC variance explained by hemodynamic-vascular factors, with an about two-times larger contribution of systemic versus local factors. We conclude that regional differences in blood supply, i.e., systemic perfusion delays, exert a stronger influence on BOLD-FC than impairments in local neurovascular coupling.

Research progress of mitophagy in chronic cerebral ischemia

Chronic cerebral ischemia (CCI), a condition that can result in headaches, dizziness, cognitive decline, and stroke, is caused by a sustained decrease in cerebral blood flow. Statistics show that 70% of patients with CCI are aged > 80 years and approximately 30% are 45-50 years. The incidence of CCI tends to be lower, and treatment for CCI is urgent. Studies have confirmed that CCI can activate the corresponding mechanisms that lead to mitochondrial dysfunction, which, in turn, can induce mitophagy to maintain mitochondrial homeostasis. Simultaneously, mitochondrial dysfunction can aggravate the insufficient energy supply to cells and various diseases caused by CCI. Regulation of mitophagy has become a promising therapeutic target for the treatment of CCI. This article reviews the latest progress in the important role of mitophagy in CCI and discusses the induction pathways of mitophagy in CCI, including ATP synthesis disorder, oxidative stress injury, induction of reactive oxygen species, and Ca2+ homeostasis disorder, as well as the role of drugs in CCI by regulating mitophagy.

Cognitive impairment in post-acute sequelae of COVID-19 and short duration myalgic encephalomyelitis patients is mediated by orthostatic hemodynamic changes

Introduction

Cognitive impairment is experienced by people with myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and post-acute sequelae of COVID-19 (PASC). Patients report difficulty remembering, concentrating, and making decisions. Our objective was to determine whether orthostatic hemodynamic changes were causally linked to cognitive impairment in these diseases.

Methods

This prospective, observational cohort study enrolled PASC, ME/CFS, and healthy controls. All participants underwent clinical evaluation and assessment that included brief cognitive testing before and after an orthostatic challenge. Cognitive testing measured cognitive efficiency which is defined as the speed and accuracy of subject's total correct responses per minute. General linear mixed models were used to analyze hemodynamics and cognitive efficiency during the orthostatic challenge. Additionally, mediation analysis was used to determine if hemodynamic instability induced during the orthostatic challenge mediated the relationship between disease status and cognitive impairment.

Results

Of the 276 participants enrolled, 256 were included in this study (34 PASC, 71 < 4 year duration ME/CFS, 69 > 10 year ME/CFS duration, and 82 healthy controls). Compared to healthy controls, the disease cohorts had significantly lower cognitive efficiency scores immediately following the orthostatic challenge. Cognitive efficiency remained low for the >10 year ME/CFS 2 and 7 days after orthostatic challenge. Narrow pulse pressure less than 25% of systolic pressure occurred at 4 and 5 min into the orthostatic challenge for the PASC and ME/CFS cohorts, respectively. Abnormally narrow pulse pressure was associated with slowed information processing in PASC patients compared to healthy controls (-1.5, p = 0.04). Furthermore, increased heart rate during the orthostatic challenge was associated with a decreased procedural reaction time in PASC and < 4 year ME/CFS patients who were 40 to 65 years of age.

Discussion

For PASC patients, both their disease state and hemodynamic changes during orthostatic challenge were associated with slower reaction time and decreased response accuracy during cognitive testing. Reduced cognitive efficiency in <4 year ME/CFS patients was associated with higher heart rate in response to orthostatic stress. Hemodynamic changes did not correlate with cognitive impairment for >10 year ME/CFS patients, but cognitive impairment remained. These findings underscore the need for early diagnosis to mitigate direct hemodynamic and other physiological effects on symptoms of cognitive impairment.

Chronic cerebral hypoperfusion: a critical feature in unravelling the etiology of vascular cognitive impairment

Vascular cognitive impairment (VCI) describes a wide spectrum of cognitive deficits related to cerebrovascular diseases. Although the loss of blood flow to cortical regions critically involved in cognitive processes must feature as the main driver of VCI, the underlying mechanisms and interactions with related disease processes remain to be fully elucidated. Recent clinical studies of cerebral blood flow measurements have supported the role of chronic cerebral hypoperfusion (CCH) as a major driver of the vascular pathology and clinical manifestations of VCI. Here we review the pathophysiological mechanisms as well as neuropathological changes of CCH. Potential interventional strategies for VCI are also reviewed. A deeper understanding of how CCH can lead to accumulation of VCI-associated pathology could potentially pave the way for early detection and development of disease-modifying therapies, thus allowing preventive interventions instead of symptomatic treatments.

Cortex-specific transcriptome profiling reveals upregulation of interferon-regulated genes after deeper cerebral hypoperfusion in mice

Background: Chronic cerebral hypoperfusion (CCH) is commonly accompanied by brain injury and glial activation. In addition to white matter lesions, the intensity of CCH greatly affects the degree of gray matter damage. However, little is understood about the underlying molecular mechanisms related to cortical lesions and glial activation following hypoperfusion. Efforts to investigate the relationship between neuropathological alternations and gene expression changes support a role for identifying novel molecular pathways by transcriptomic mechanisms.

Methods: Chronic cerebral ischemic injury model was induced by the bilateral carotid artery stenosis (BCAS) using 0.16/0.18 mm microcoils. Cerebral blood flow (CBF) was evaluated using laser speckle contrast imaging (LSCI) system. Spatial learning and memory were assessed by Morris water maze test. Histological changes were evaluated by Hematoxylin staining. Microglial activation and neuronal loss were further examined by immunofluorescence staining. Cortex-specific gene expression profiling analysis was performed in sham and BCAS mice, and then validated by quantitative RT-PCR and immunohistochemistry (IHC).

Results: In our study, compared with the sham group, the right hemisphere CBF of BCAS mice decreased to 69% and the cognitive function became impaired at 4 weeks postoperation. Besides, the BCAS mice displayed profound gray matter damage, including atrophy and thinning of the cortex, accompanied by neuronal loss and increased activated microglia. Gene set enrichment analysis (GSEA) revealed that hypoperfusion-induced upregulated genes were significantly enriched in the pathways of interferon (IFN)-regulated signaling along with neuroinflammation signaling. Ingenuity pathway analysis (IPA) predicted the importance of type I IFN signaling in regulating the CCH gene network. The obtained RNA-seq data were validated by qRT-PCR in cerebral cortex, showing consistency with the RNA-seq results. Also, IHC staining revealed elevated expression of IFN-inducible protein in cerebral cortex following BCAS-hypoperfusion.

Conclusion: Overall, the activation of IFN-mediated signaling enhanced our understanding of the neuroimmune responses induced by CCH. The upregulation of IFN-regulated genes (IRGs) might exert a critical impact on the progression of cerebral hypoperfusion. Our improved understanding of cortex-specific transcriptional profiles will be helpful to explore potential targets for CCH.

CCL21/CCR7 axis regulates demyelination and vascular cognitive impairment in a mouse model for chronic cerebral hypoperfusion

OBJECTIVES

White matter lesions (WML) are usually accompanied by cognitive decline, which consist of axonal loss and demyelination. CC chemokine ligand 21 (CCL21) and its receptor C-C chemokine receptor 7 (CCR7) belong to the chemokine family, which are involved in many diseases. However, their function in the central nervous system (CNS) is still unexplored. This study aimed to explore the role of CCL21/CCR7 axis in the pathological process of chronic ischemia-induced WML.

METHODS

Bilateral common carotid artery stenosis (BCAS) was employed in C57BL/6 mice as the in vivo WML model. Microarray analysis was performed to detect the overall molecular changes induced in the endothelial cells by BCAS. Q-PCR, Western blotting, and immunofluorescence staining were performed to evaluate expression levels of the related molecules. The mice were injected with LV-CCL21-GFP virus in the corpus callosum to overexpress CCL21. WML degree was determined via MRI, and cognitive ability was assessed by Y-maze and novel object recognition tests. Myelin sheath integrity was evaluated via immunofluorescence staining.

RESULTS

CCL21 was significantly downregulated in endothelial cells after BCAS and CCL21 overexpression alleviated BCAS-induced cognitive deficits and demyelination. Furthermore, CCR7 was found to be mainly expressed in oligodendrocytes (OLs) after exposed to hypoxia and CCR7 silencing blocked the protective effects induced by CCL21 overexpression. Conclusions CCL21/CCR7 axis may play a key role in demyelination induced by BCAS. This might provide a novel therapeutic target for WML.

VCAM1 Drives Vascular Inflammation Leading to Continuous Cortical Neuronal Loss Following Chronic Cerebral Hypoperfusion

BACKGROUND

Chronic cerebral hypoperfusion (CCH) is associated with neuronal loss and blood-brain barrier (BBB) impairment in vascular dementia (VaD). However, the relationship and the molecular mechanisms between BBB dysfunction and neuronal loss remain elusive.

OBJECTIVE

We explored the reasons for neuron loss following CCH.

METHODS

Using permanent bilateral common carotid artery occlusion (2VO) rat model, we observed the pathological changes of cortical neurons and BBB in the sham group as well as rats 3d, 7d, 14d and 28d post 2VO. In order to further explore the factors influencing neuron loss following CCH with regard to cortical blood vessels, we extracted cortical brain microvessels at five time points for transcriptome sequencing. Finally, integrin receptor a4β1 (VLA-4) inhibitor was injected into the tail vein, and cortical neuron loss was detected again.

RESULTS

We found that cortical neuron loss following CCH is a continuous process, but damage to the BBB is acute and transient. Results of cortical microvessel transcriptome analysis showed that biological processes related to vascular inflammation mainly occurred in the chronic phase. Meanwhile, cell adhesion molecules, cytokine-cytokine receptor interaction were significantly changed at this phase. Among them, the adhesion molecule VCAM1 plays an important role. Using VLA-4 inhibitor to block VCAM1-VLA-4 interaction, cortical neuron damage was ameliorated at 14d post 2VO.

CONCLUSION

Injury of the BBB may not be the main reason for persistent loss of cortical neurons following CCH. The continuous inflammatory response within blood vessels maybe an important factor in the continuous loss of cortical neurons following CCH.

The impact of cerebral vasomotor reactivity on cerebrovascular diseases and cognitive impairment

The regulation of cerebral blood flow (CBF) is a complex and tightly controlled function ensuring delivery of oxygen and nutrients and removal of metabolic wastes from brain tissue. Cerebral vasoreactivity (CVR) refers to the ability of the nervous system to regulate CBF according to metabolic demands or changes in the microenvironment. This can be assessed through a variety of nuclear medicine and imaging techniques and protocols. Several studies have investigated the association of CVR with physiological and pathological conditions, with particular reference to the relationship with cognitive impairment and cerebrovascular disorders (CVD). A better understanding of the interaction between CVR and cognitive dysfunction in chronic and particularly acute CVD could help improving treatment and rehabilitation strategies in these patients. In this paper, we reviewed current knowledge on CVR alterations in the context of acute and chronic CVD and cognitive dysfunction. Alterations in CVR and hemodynamics have been described in patients with both neurodegenerative and vascular cognitive impairment, and the severity of these alterations seems to correlate with CVR derailment. Furthermore, an increased risk of cognitive impairment progression has been associated with alterations in CVR parameters and hemodynamics. Few studies have investigated these associations in acute cerebrovascular disorders and the results are inconsistent; thus, further research on this topic is encouraged.

Neuroprotective Effects of Theobromine in permanent bilateral common carotid artery occlusion rat model of cerebral hypoperfusion

Cerebral hypoperfusion (CH) is a common underlying mechanism of dementia disorders linked to aberrations in the neurovascular unit. Hemodynamic disturbances adversely affect cellular energy homeostasis that triggers a sequence of events leading to irrevocable damage to the brain and neurobehavioral discrepancies. Theobromine is a common ingredient of many natural foods consumed by a large population worldwide. Theobromine has shown health benefits in several studies, attributed to regulation of calcium homeostasis, phosphodiesterase, neurotransmission, and neurotrophins. The current study evaluated the neuroprotective potential of theobromine against CH in the permanent bilateral common carotid artery occlusion (BCCAO) prototype. Wistar rats were distributed in Sham-operated (S), S + T100, CH, CH + T50, and CH + T100 groups. Animals received permanent BCCAO or Sham treatment on day 1. Theobromine (50, 100 mg/kg) was given orally in animals subjected to BCCAO for 14 days daily. CH caused neurological deficits (12-point scale), motor dysfunction, and memory impairment in rats. Treatment with theobromine significantly attenuated neurological deficits and improved sensorimotor functions and memory in rats with CH. In biochemistry investigation of the entire brain, findings disclosed reduction in brain oxidative stress, inflammatory intermediaries (tumor necrosis factor-α, interleukin-1β and - 6, nuclear factor-κB), markers of cell demise (lactate dehydrogenase, caspase-3), acetylcholinesterase activity, and improvement in γ-aminobutyric acid quantity in rats that were given theobromine for 14 days daily after CH. Histopathological analysis substantiated attenuation of neurodegenerative changes by theobromine. The findings of this study indicated that theobromine could improve neurological scores, sensorimotor abilities, and memory in CH prototype.

Blood–Brain Barrier Dysfunction and the Potential Mechanisms in Chronic Cerebral Hypoperfusion Induced Cognitive Impairment

Chronic cerebral hypoperfusion (CCH) is a major cause of vascular cognitive impairment and dementia (VCID). Although the underlying mechanisms have not been fully elucidated, the emerging data suggest that blood–brain barrier (BBB) dysfunction is one of the pivotal pathological changes in CCH. BBB dysfunction appears early in CCH, contributing to the deterioration of white matter and the development of cognitive impairment. In this review, we summarize the latest experimental and clinical evidence implicating BBB disruption as a major cause of VCID. We discuss the mechanisms of BBB dysfunction in CCH, focusing on the cell interactions within the BBB, as well as the potential role of APOE genotype. In summary, we provide novel insights into the pathophysiological mechanisms underlying BBB dysfunction and the potential clinical benefits of therapeutic interventions targeting BBB in CCH.

Serum glial fibrillary acidic protein indicates memory impairment in patients with chronic heart failure

Aims

Cognitive dysfunction occurs frequently in patients with heart failure (HF), but early detection remains challenging. Serum glial fibrillary acidic protein (GFAP) is an emerging biomarker of cognitive decline in disorders of primary neurodegeneration such as Alzheimer's disease. We evaluated the utility of serum GFAP as a biomarker for cognitive dysfunction and structural brain damage in patients with stable chronic HF.

Methods and results

Using bead‐based single molecule immunoassays, we quantified serum levels of GFAP in patients with HF participating in the prospective Cognition.Matters‐HF study. Participants were extensively phenotyped, including cognitive testing of five separate domains and magnetic resonance imaging (MRI) of the brain. Univariable and multivariable models, also accounting for multiple testing, were run. One hundred and forty‐six chronic HF patients with a mean age of 63.8 ± 10.8 years were included (15.1% women). Serum GFAP levels (median 246 pg/mL, quartiles 165, 384 pg/mL; range 66 to 1512 pg/mL) did not differ between sexes. In the multivariable adjusted model, independent predictors of GFAP levels were age (T = 5.5; P < 0.001), smoking (T = 3.2; P = 0.002), estimated glomerular filtration rate (T = −4.7; P < 0.001), alanine aminotransferase (T = −2.1; P = 0.036), and the left atrial end‐systolic volume index (T = 3.4; P = 0.004). NT‐proBNP but not serum GFAP explained global cerebral atrophy beyond ageing. However, serum GFAP levels were associated with the cognitive domain visual/verbal memory (T = −3.0; P = 0.003) along with focal hippocampal atrophy (T = 2.3; P = 0.025).

Conclusions

Serum GFAP levels are affected by age, smoking, and surrogates of the severity of HF. The association of GFAP with memory dysfunction suggests that astroglial pathologies, which evade detection by conventional MRI, may contribute to memory loss beyond ageing in patients with chronic HF.

A Pilot Study of Radiomic Based on Routine CT Reflecting Difference of Cerebral Hemispheric Perfusion

Background

To explore the effectiveness of radiomics features based on routine CT to reflect the difference of cerebral hemispheric perfusion.

Methods

We retrospectively recruited 52 patients with severe stenosis or occlusion in the unilateral middle cerebral artery (MCA), and brain CT perfusion showed an MCA area with deficit perfusion. Radiomics features were extracted from the stenosis side and contralateral of the MCA area based on precontrast CT. Two different region of interest drawing methods were applied. Then the patients were randomly grouped into training and testing sets by the ratio of 8:2. In the training set, ANOVA and the Elastic Net Regression with fivefold cross-validation were conducted to filter and choose the optimized features. Moreover, different machine learning models were built. In the testing set, the area under the receiver operating characteristic (AUC) curve, calibration, and clinical utility were applied to evaluate the predictive performance of the models.

Results

The logistic regression (LR) for the triangle-contour method and artificial neural network (ANN) for the semiautomatic-contour method were chosen as radiomics models for their good prediction efficacy in the training phase (AUC = 0.869, 0.873) and the validation phase (AUC = 0.793, 0.799). The radiomics algorithms of the triangle-contour and semiautomatic-contour method were implemented in the whole training set (AUC = 0.870, 0.867) and were evaluated in the testing set (AUC = 0.760, 0.802). According to the optimal cutoff value, these two methods can classify the vascular stenosis side class and normal side class.

Conclusion

Radiomic predictive feature based on precontrast CT image could reflect the difference of cerebral hemispheric perfusion to some extent.

The role of inflammasomes in vascular cognitive impairment

There is an increasing prevalence of Vascular Cognitive Impairment (VCI) worldwide, and several studies have suggested that Chronic Cerebral Hypoperfusion (CCH) plays a critical role in disease onset and progression. However, there is a limited understanding of the underlying pathophysiology of VCI, especially in relation to CCH. Neuroinflammation is a significant contributor in the progression of VCI as increased systemic levels of the proinflammatory cytokine interleukin-1β (IL-1β) has been extensively reported in VCI patients. Recently it has been established that CCH can activate the inflammasome signaling pathways, involving NLRP3 and AIM2 inflammasomes that critically regulate IL-1β production. Given that neuroinflammation is an early event in VCI, it is important that we understand its molecular and cellular mechanisms to enable development of disease-modifying treatments to reduce the structural brain damage and cognitive deficits that are observed clinically in the elderly. Hence, this review aims to provide a comprehensive insight into the molecular and cellular mechanisms involved in the pathogenesis of CCH-induced inflammasome signaling in VCI.

Orthostatic Challenge Causes Distinctive Symptomatic, Hemodynamic and Cognitive Responses in Long COVID and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Background

Some patients with acute COVID-19 are left with persistent, debilitating fatigue, cognitive impairment ("brain fog"), orthostatic intolerance (OI) and other symptoms ("Long COVID"). Many of the symptoms are like those of other post-infectious fatigue syndromes and may meet criteria for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Common diagnostic laboratory tests are often unrevealing.

Methods

We evaluated whether a simple, standardized, office-based test of OI, the 10-min NASA Lean Test (NLT), would aggravate symptoms and produce objective hemodynamic and cognitive abnormalities, the latter being evaluated by a simple smart phone-based app.

Participants

People with Long COVID (N = 42), ME/CFS (N = 26) and healthy control subjects (N = 20) were studied just before, during, immediately after, 2 and 7 days following completion of the NLT.

Results

The NLT provoked a worsening of symptoms in the two patient groups but not in healthy control subjects, and the severity of all symptoms was similar and significantly worse in the two patient groups than in the control subjects (p < 0.001). In the two patient groups, particularly those with Long COVID, the NLT provoked a marked and progressive narrowing in the pulse pressure. All three cognitive measures of reaction time worsened in the two patient groups immediately following the NLT, compared to the healthy control subjects, particularly in the Procedural Reaction Time (p < 0.01).

Conclusions

A test of orthostatic stress easily performed in an office setting reveals different symptomatic, hemodynamic and cognitive abnormalities in people with Long COVID and ME/CFS, compared to healthy control subjects. Thus, an orthostatic challenge easily performed in an office setting, and the use of a smart phone app to assess cognition, can provide objective confirmation of the orthostatic intolerance and brain fog reported by patients with Long COVID and ME/CFS.

Pharmacological Actions of Myricetin in the Nervous System: A Comprehensive Review of Preclinical Studies in Animals and Cell Models

Myricetin is a natural flavonoid extracted from a variety of plants, such as medicinal herbs, vegetables, berries, and tea leaves. A growing body of evidence has reported that myricetin supplementation display therapeutic activities in a lot of nervous system disorders, such as cerebral ischemia, Alzheimer’s disease, Parkinson’s disease, epilepsy, and glioblastoma. Myricetin supplementation can also protect against pathological changes and behavioral impairment induced by multiple sclerosis and chronic stress. On the basis of these pharmacological actions, myricetin could be developed as a potential drug for the prevention and/or treatment of nervous system disorders. Mechanistic studies have shown that inhibition of oxidative stress, cellular apoptosis, and neuroinflammatory response are common mechanisms for the neuroprotective actions of myricetin. Other mechanisms, including the activation of the nuclear factor E2-related factor 2 (Nrf2), extracellular signal-regulated kinase 1/2 (ERK1/2), protein kinase B (Akt), cyclic adenosine monophosphate-response element binding protein (CREB), and brain-derived neurotrophic factor (BDNF) signaling, inhibition of intracellular Ca²⁺ increase, inhibition of c-Jun N-terminal kinase (JNK)-p38 activation, and suppression of mutant protein aggregation, may also mediate the neuroprotective effects of myricetin. Furthermore, myricetin treatment has been shown to promote the activation of the inhibitory neurons in the hypothalamic paraventricular nucleus, which subsequently produces anti-epilepsy effects. In this review, we make a comprehensive understanding about the pharmacological effects of myricetin in the nervous system, aiming to push the development of myricetin as a novel drug for the treatment of nervous system disorders.

Xi-Xian-Tong-Shuan capsule alleviates vascular cognitive impairment in chronic cerebral hypoperfusion rats by promoting white matter repair, reducing neuronal loss, and inhibiting the expression of pro-inflammatory factors

BACKGROUND

While the number of cases of vascular cognitive impairment caused by chronic cerebral hypoperfusion (CCH) has been increasing every year, there are currently no clinically effective treatment methods. At present, Xi-Xian-Tong-Shuan capsule is predominantly used in patients with acute cerebral ischemia; however, its protective effect on CCH has rarely been reported.

OBJECTIVE

To explore the underlying mechanisms by which Xi-Xian-Tong-Shuan capsule alleviates cognitive impairment caused by CCH.

METHODS

A model of CCH was established in specific-pathogen-free (SPF)-grade male Sprague-Dawley (SD) rats using bilateral common carotid artery occlusion (BCCAO). Xi-Xian-Tong-Shuan capsules were intragastrically administered for 42 days after the BCCAO surgery. We then assessed for changes in cognitive function, expression levels of pro-inflammatory factors, and coagulation function as well as for the presence of white matter lesions and neuronal loss. One-way ANOVA and Tukey's test were used to analyze the experimental data.

RESULTS

The rats showed significant cognitive dysfunction after the BCCAO surgery along with white matter lesions, a loss of neurons, and elevated levels of inflammatory factors, all of which were significantly reversed after intervention with Xi-Xian-Tong-Shuan capsules.

CONCLUSION

Xi-Xian-Tong-Shuan capsules can ameliorate vascular cognitive impairment in CCH rats by preventing damage of white matter, reducing neuronal loss, and inhibiting the expression of pro-inflammatory factors. Our study provides a new reference for the clinical treatment of chronic cerebral ischemia with Xi-Xian-Tong-Shuan capsules.

Delirium and Clusters of Older Patients Affected by Multimorbidity in Acute Hospitals

OBJECTIVES

Delirium is commonly seen in older adults with multimorbidity, during a hospitalization, resulting from the interplay between predisposing factors such as advanced age, frailty, and dementia, and a series of precipitating factors. The association between delirium and specific multimorbidity is largely unexplored so far although of potential key relevance for targeted interventions. The aim of the study was to check for a potential association of multimorbidity with delirium in a large cohort of older patients hospitalized for an acute medical or surgical condition.

DESIGN

This is a cross-sectional study nested in the 2017 Delirium Day project.

SETTING AND PARTICIPANTS

The study includes 1829 hospitalized patients (age: 81.8, SD: 5.5). Of them, 419 (22.9%) had delirium.

METHODS

Sociodemographic and medical history were collected. The 4AT was used to assess the presence of delirium. The Charlson Comorbidity index was used to assess multimorbidity.

RESULTS

The results identified neurosensorial multimorbidity as the most prevalent, including patients with dementia, cerebrovascular diseases, and sensory impairments. In light of the highest co-occurrence of 3 neurosensorial chronic conditions, we could hypothesize that a baseline altered brain functional and neural connectivity might determine the vulnerability signature for incipient overall system disruption in presence of acute insults.

CONCLUSIONS AND IMPLICATIONS

Eventually, our findings moved a step forward in supporting the key importance of routine screening for sensory impairments and cognitive status of older patients for the highest risk of in-hospital delirium. In fact, preventive interventions could be particularly relevant and effective in preventing delirium in such vulnerable populations and might help refining this early diagnosis.

The cellular basis of increased PET hypoxia tracer uptake in focal cerebral ischemia with comparison between [18F]FMISO and [64Cu]CuATSM

PET hypoxia imaging can assess tissue viability in acute ischemic stroke (AIS). [18F]FMISO is an established tracer but requires substantial accumulation time, limiting its use in hyperacute AIS. [64Cu]CuATSM requires less accumulation time and has shown promise as a hypoxia tracer. We compared these tracers in a M2-occlusion model (M2CAO) with preserved collateral blood flow. Rats underwent M2CAO and [18F]FMISO (n = 12) or [64Cu]CuATSM (n = 6) examinations. [64Cu]CuATSM animals were also examined with MRI. Pimonidazole was used as a surrogate for [18F]FMISO in an immunofluorescence analysis employed to profile levels of hypoxia in neurons (NeuN) and astrocytes (GFAP). There was increased [18F]FMISO uptake in the M2CAO cortex. No increase in [64Cu]CuATSM activity was found. The pimonidazole intensity of neurons and astrocytes was increased in hypoxic regions. The pimonidazole intensity ratio was higher in neurons than in astrocytes. In the majority of animals, immunofluorescence revealed a loss of astrocytes within the core of regions with increased pimonidazole uptake. We conclude that [18F]FMISO is superior to [64Cu]CuATSM in detecting hypoxia in AIS, consistent with an earlier study. [18F]FMISO may provide efficient diagnostic imaging beyond the hyperacute phase. Results do not provide encouragement for the use of [64Cu]CuATSM in experimental AIS.

Are cortical microvascular raspberries caused by cerebral hypoperfusion? An exploratory pathological study

•

An exploratory study on the ‘raspberry’, a type of cortical microvascular formation.

•

Hypothesis: raspberries form by angiogenesis induced by cerebral hypoperfusion.

•

Are raspberries associated with clinical or pathological markers of hypoperfusion?

•

Data: histopathological raspberry quantification, medical records, autopsy reports.

•

Raspberries were associated with atherosclerosis of the basal cerebral arteries.

Introduction

This retrospective study investigated a cortical microvascular formation, termed a ‘raspberry’ due to its appearance under a bright-field microscope. We examined whether there is support for the hypothesis that raspberry formation is an angiogenic process induced by cerebral hypoperfusion.

Materials and Methods

Raspberries were manually quantified in haematoxylin and eosin-stained cortical sections from the anterior frontal lobe of deceased individuals who had undergone a diagnostic neuropathological examination at the Department of Pathology, Lund, Sweden, during April 2019–January 2021. Subjects represented consecutively received cases during this 22-month period. The raspberry density was compared between subjects according to variables collected from medical records and autopsy reports: age, sex, hypertension, diabetes mellitus, atrial fibrillation, orthostatic hypotension, chronic heart failure, acute circulatory failure, aortic atherosclerosis, atherosclerosis of the basal cerebral arteries (referred to as ‘cerebral atherosclerosis’), cerebral small vessel disease, cerebral amyloid angiopathy, cerebral infarction, and ischaemic white matter disease.

Results

62 subjects were included. The mean age was 71.9 years (range 46–97 years). 21 subjects (33.9%) were female. Independent-samples t-test showed a higher raspberry density in subjects with cerebral atherosclerosis (p = 0.029; 95% CI 0.7, 11.6 raspberries/cm²). The higher raspberry density in subjects with cerebral atherosclerosis remained in multiple linear regression (p = 0.003; 95% CI 2.3, 11.1 raspberries/cm²).

Conclusion

This exploratory study indicates that cortical raspberries could be associated with cerebral atherosclerosis. The remaining results were inconclusive but motivate further examination of variables such as acute circulatory failure.

An Overview on the Differential Interplay Among Neurons-Astrocytes-Microglia in CA1 and CA3 Hippocampus in Hypoxia/Ischemia

Neurons have been long regarded as the basic functional cells of the brain, whereas astrocytes and microglia have been regarded only as elements of support. However, proper intercommunication among neurons-astrocytes-microglia is of fundamental importance for the functional organization of the brain. Perturbation in the regulation of brain energy metabolism not only in neurons but also in astrocytes and microglia may be one of the pathophysiological mechanisms of neurodegeneration, especially in hypoxia/ischemia. Glial activation has long been considered detrimental for survival of neurons, but recently it appears that glial responses to an insult are not equal but vary in different brain areas. In this review, we first take into consideration the modifications of the vascular unit of the glymphatic system and glial metabolism in hypoxic conditions. Using the method of triple-labeling fluorescent immunohistochemistry coupled with confocal microscopy (TIC), we recently studied the interplay among neurons, astrocytes, and microglia in chronic brain hypoperfusion. We evaluated the quantitative and morpho-functional alterations of the neuron-astrocyte-microglia triads comparing the hippocampal CA1 area, more vulnerable to ischemia, to the CA3 area, less vulnerable. In these contiguous and interconnected areas, in the same experimental hypoxic conditions, astrocytes and microglia show differential, finely regulated, region-specific reactivities. In both areas, astrocytes and microglia form triad clusters with apoptotic, degenerating neurons. In the neuron-astrocyte-microglia triads, the cell body of a damaged neuron is infiltrated and bisected by branches of astrocyte that create a microscar around it while a microglial cell phagocytoses the damaged neuron. These coordinated actions are consistent with the scavenging and protective activities of microglia. In hypoxia, the neuron-astrocyte-microglia triads are more numerous in CA3 than in CA1, further indicating their protective effects. These data, taken from contiguous and interconnected hippocampal areas, demonstrate that glial response to the same hypoxic insult is not equal but varies significantly. Understanding the differences of glial reactivity is of great interest to explain the differential susceptibility of hippocampal areas to hypoxia/ischemia. Further studies may evidence the differential reactivity of glia in different brain areas, explaining the higher or lower sensitivity of these areas to different insults and whether glia may represent a target for future therapeutic interventions.

Small Vessel Disease-Related Dementia: An Invalid Neurovascular Coupling?

The arteriosclerosis-dependent alteration of brain perfusion is one of the major determinants in small vessel disease, since small vessels have a pivotal role in the brain's autoregulation. Nevertheless, as far as we know, endothelium distress can potentiate the flow dysregulation and lead to subcortical vascular dementia that is related to small vessel disease (SVD), also being defined as subcortical vascular dementia (sVAD), as well as microglia activation, chronic hypoxia and hypoperfusion, vessel-tone dysregulation, altered astrocytes, and pericytes functioning blood-brain barrier disruption. The molecular basis of this pathology remains controversial. The apparent consequence (or a first event, too) is the macroscopic alteration of the neurovascular coupling. Here, we examined the possible mechanisms that lead a healthy aging process towards subcortical dementia. We remarked that SVD and white matter abnormalities related to age could be accelerated and potentiated by different vascular risk factors. Vascular function changes can be heavily influenced by genetic and epigenetic factors, which are, to the best of our knowledge, mostly unknown. Metabolic demands, active neurovascular coupling, correct glymphatic process, and adequate oxidative and inflammatory responses could be bulwarks in defense of the correct aging process; their impairments lead to a potentially catastrophic and non-reversible condition.