Central nervous system complications associated with SARS-CoV-2 infection: integrative concepts of pathophysiology and case reports

Seven-tesla magnetic resonance imaging of the nervus terminalis, olfactory tracts, and olfactory bulbs in COVID-19 patients with anosmia and hypogeusia

Introduction

Linking olfactory epithelium to the central nervous system are cranial nerve 1, the olfactory nerve, and cranial nerve "0," and the nervus terminalis (NT). Since there is minimal expression of angiotensin-converting enzyme-2 (ACE-2) in the olfactory nerve, it is unclear how SARS-CoV-2 causes anosmia (loss of smell) and hypogeusia (reduction of taste). In animal models, NT expresses ACE-2 receptors, suggesting a possible SARS-CoV-2 viral entry site in humans. The purpose of this study was to determine whether ultra-high-field 7 T magnetic resonance imaging (MRI) could visualize the NT, olfactory bulbs (OB), and olfactory tract (OT) in healthy controls and COVID-19 anosmia or hypogeusia and to qualitatively assess for volume loss and T2 alterations.

Methods

In this study, 7 T MRI was used to evaluate the brain and olfactory regions in 45 COVID-19 patients and 29 healthy controls. Neuroimaging was qualitatively assessed by four board-certified neuroradiologists who were blinded to outcome assignments: for the presence or absence of NT; for OB, OT, and brain volume loss; and altered T2 signal, white matter T2 hyperintensities, microhemorrhages, enlarged perivascular spaces, and brainstem involvement.

Results

NT was identifiable in all COVID-19 patients and controls. T2 hyperintensity in the NT, OB, and OT in COVID-19 patients with anosmia or hypogeusia was statistically significant compared to controls and COVID-19 patients without anosmia or hypogeusia.

Discussion

On 7 T MRI, NT was radiographically identifiable, adjacent to OB and OT. In COVID-19 anosmia and hypogeusia, T2 hyperintensity of NT, OB, and OT was statistically significant compared to COVID-19 patients without anosmia or hypogeusia and controls. The NT may be a potential entry site for SARs-CoV-2 and may play a role in the pathophysiology of COVID-19 anosmia.

Efficacy of Donepezil for Fatigue and Psychological Symptoms in Post-COVID-19 Condition: Study Protocol for a Multicenter Randomized, Placebo-controlled, Double-blind Trial

BACKGROUND

Approximately 30% of coronavirus disease 2019 COVID-19 patients develop fatigue and psychological symptoms. We previously demonstrated the efficacy of donepezil, an acetylcholinesterase inhibitor that is widely used to treat dementia, in basic research.

METHODS

This is a multicenter, double-blind, randomized, controlled, phase II clinical trial in which 120 patients with COVID-19 will be randomized in a 1:1 ratio to a donepezil or placebo group. Inclusion criteria are as follows: (1) Adult. (2) With COVID-19 infection who had an upper respiratory tract infection, fever, or cough in the acute phase. (3) With a global binary fatigue score ≥4 on the Chalder Fatigue Scale assessment (4) Within 52 weeks of the onset of COVID-19. (5) Patients who provide consent themselves. In the donepezil group, a low dose (3 mg/day) is administered for the first week and is increased to 5 mg/day for 2 weeks. The control group receives placebo for 3 weeks. The primary endpoint is a change in and the absolute value of the Chalder Fatigue Scale score after 3 weeks of treatment. Secondary endpoints are a change in and the absolute value of the Chalder Fatigue Scale score after 8 weeks of treatment, the other mental scores after 3 and 8 weeks of treatment, a symptom survey, adverse events, and medication compliance rate.

RESULTS

This study protocol is ongoing and the results will be analyzed in April 2024.

CONCLUSIONS

The off-label use of donepezil at the default dose for dementia has potential for the treatment of post-COVID-19 condition.

Risk of COVID-19 infection and seizure exacerbation among patients with epilepsy during the peak of Omicron wave

OBJECTIVES

Existing data regarding the risk of COVID-19 infection and its effects on seizure control in patients with epilepsy (PWE) are inconclusive. Our research aims to investigate the PWE who are susceptible to COVID-19 and what factors contribute to seizure exacerbation.

METHODS

From Dec 28, 2022 to Feb 19, 2023, a cross-sectional questionnaire survey among adult PWE was conducted. The demographics, epilepsy-related information, COVID-19-related variables, and seizure outcomes after COVID-19 infection were collected. Multivariate logistic analyses were performed to determine the risk factors associated with COVID-19 infection and exacerbated seizures.

RESULTS

Of 1557 PWE, 829 (53.2%) were infected with COVID-19 and 136 (16.4%) developed seizure exacerbation after COVID-19 infection. Overweight/obesity (OR 1.372, 95% CI 1.075-1.753, p = 0.011), immunocompromised (OR 3.301, 95% CI 1.093-9.974, p = 0.031), active epilepsy (OR 1.700, 95% CI 1.378-2.097, p < 0.001), and antiseizure medication (ASM) polytherapy (OR 1.314, 95% CI 1.065-1.621, p = 0.011) were associated with COVID-19 infection. Active epilepsy (OR 4.696, 95% CI 2.568-8.586, p < 0.001) and fever-associated seizures (OR 4.298, 95%CI 2.659-6.946, p < 0.001) were associated with seizure exacerbation.

SIGNIFICANCE

PWE with overweight/obesity, immunocompromised, active epilepsy, and ASM polytherapy were at higher risk of COVID-19 infection. Once infected with COVID-19, seizures were exacerbated in PWE with active epilepsy and fever-associated seizures.

PLAIN LANGUAGE SUMMARY

Patients with epilepsy (PWE) do not appear to be more susceptible to COVID-19 infection than general population. Once infected with COVID-19, 16.4% of PWE had seizure exacerbation. The PWE who have experienced seizures within the past 12 months before infection tend to contract COVID-19 more often, and are more likely to experience seizure exacerbations following COVID-19 infection.

Clinical and diagnostic features of long-COVID patients presenting with neurologic symptoms in Chicago

Long COVID, a condition characterized by persistent symptoms after COVID-19 infection, is increasingly being recognized worldwide. Neurologic symptoms are frequently reported in survivors of COVID-19, making it crucial to better understand this phenomenon both on a societal scale and for the quality of life of these patients. Between January 1, 2020, and July 31, 2022, Illinois (IL) had a standardized cumulative death rate that ranked it 24th out of the 51 states in the United States (US). However, the US had one of the highest per capita COVID-19 death rates among large, high-income countries. [Bollyky T. et al. 2023] As a result of the increased number of COVID-19 infections, there was a rise in the number of patients experiencing Long COVID. At our neuro-infectious disease clinic in Chicago (IL), we observed an increasing number of patients presenting with cognitive and other neurologic symptoms after contracting COVID-19. Initially, we needed to provide these individuals with a better understanding of their condition and expected outcomes. We were thus motivated to further evaluate this group of patients for any patterns in presentation, neurologic findings, and diagnostic testing that would help us better understand this phenomenon. We aim to contribute to the growing body of research on Long COVID, including its presentation, diagnostic testing results, and outcomes to enlighten the long COVID syndrome. We hypothesize that the neurological symptoms resulting from long COVID persist for over 12 months. We conducted a retrospective analysis of clinical data from 44 patients with long-COVID. Cognitive symptoms were the most common presenting concern. Abnormalities in Montreal Cognitive Assessment, electroencephalogram, serum autoantibody testing, and cerebrospinal fluid were found in minority subsets of our cohort. At 12 months, most patients continue to experience neurologic symptoms, though more than half reported moderate or marked improvement compared to initial presentation. Although most of the patients in this study did not show a consistent occurrence of symptoms suggesting a cohesive underlying etiology, our clinical data demonstrated some features of Long COVID patients in Chicago (IL) that could lead to new research avenues, helping us better understand this syndrome that affects patients worldwide.

Exploring Symptom Overlaps: Post-COVID-19 Neurological Syndrome and Post-Concussion Syndrome in Athletes

The COVID-19 pandemic has introduced new challenges in managing neurological conditions, particularly among athletes. This paper explores the intersection of post-COVID-19 neurological syndrome (PCNS/PASC) and post-concussion syndrome (PCS), focusing on their implications in sports medicine. Our analysis covers the symptomatology, pathophysiology, and management strategies for PCNS/PASC and PPCS, with special attention paid to the unique challenges faced by athletes recovering from these conditions, including the risk of symptom exacerbation and prolonged recovery. Key findings reveal that both PCNS/PASC and PPCS present with overlapping symptoms such as cognitive difficulties, exercise intolerance, and mental health issues, but differ in specific manifestations like anosmia and ageusia, unique to COVID-19. Pathophysiological analysis reveals similarities in blood-brain barrier disruption (BBB) but differences in the extent of immune activation. Management strategies emphasize a gradual increase in physical activity, close symptom monitoring, and psychological support, with a tailored approach for athletes. Specific interventions include progressive aerobic exercises, resistance training, and cognitive rehabilitation. Furthermore, our study highlights the importance of integrating neurology, psychiatry, physical therapy, and sports medicine to develop comprehensive care strategies. Our findings underscore the dual challenge of COVID-19 and concussion in athletes, necessitating a nuanced, interdisciplinary approach to effective management. Future research should focus on the long-term neurological effects of both conditions and optimizing treatment protocols to improve patient outcomes. This comprehensive understanding is crucial for advancing the management of athletes affected by these overlapping conditions and ensuring their safe return to sports.

Long COVID in Brain Health Research: A Call to Action

The COVID-19 pandemic has brought attention to the long-term consequences of the virus, particularly the persistent symptoms that characterize long COVID. This syndrome, which can last for months after the initial infection, includes a range of neurological and neuropsychiatric manifestations that have significant implications for brain health and dementia research. This review explores the current understanding of long COVID's cognitive, neurological, and psychiatric symptoms and their potential impact on brain stimulation and neuroimaging studies. It argues that researchers must adapt their study designs and screening processes to account for the confounding effects of long COVID and ensure the accuracy and reliability of their findings. To advance the understanding of this condition and its long-term effects on brain health, the review proposes a series of strategies, including the development of standardized screening tools, the investigation of underlying mechanisms, and the identification of risk factors and protective factors. It also emphasizes the importance of collaborative research efforts and international data sharing platforms in accelerating the pace of discovery and developing targeted interventions for individuals with long COVID. As the prevalence of this condition continues to grow, it is imperative that the neuroscience community comes together to address this challenge and support those affected by long COVID.

Interplay of Demographic Influences, Clinical Manifestations, and Longitudinal Profile of Laboratory Parameters in the Progression of SARS-CoV-2 Infection: Insights from the Saudi Population

Understanding the factors driving SARS-CoV-2 infection progression and severity is complex due to the dynamic nature of human physiology. Therefore, we aimed to explore the severity risk indicators of SARS-CoV-2 through demographic data, clinical manifestations, and the profile of laboratory parameters. The study included 175 patients either hospitalized at King Abdulaziz Medical City-Riyadh or placed in quarantine at designated hotels in Riyadh, Saudi Arabia, from June 2020 to April 2021. Hospitalized patients were followed up through the first week of admission. Demographic data, clinical presentations, and laboratory results were retrieved from electronic patient records. Our results revealed that older age (OR: 1.1, CI: [1.1-1.12]; p < 0.0001), male gender (OR: 2.26, CI: [1.0-5.1]; p = 0.047), and blood urea nitrogen level (OR: 2.56, CI: [1.07-6.12]; p = 0.034) were potential predictors of severity level. In conclusion, the study showed that apart from laboratory parameters, age and gender could potentially predict the severity of SARS-CoV-2 infection in the early stages. To our knowledge, this study is the first in Saudi Arabia to explore the longitudinal profile of laboratory parameters among risk factors, shedding light on SARS-CoV-2 infection progression parameters.

Proteomic and metabolomic analysis of the serum of patients with tick-borne encephalitis

Tick-borne encephalitis virus (TBEV) is a common virus in Europe and Asia, causing around 10,000 to 10,500 infections annually. It affects the central nervous system and poses threats to public health. However, the exact molecular mechanisms of TBE pathogenesis are not yet fully understood due to the complex interactions between the virus and its host. In this study, a comprehensive analysis was conducted to characterize the serum metabolome and proteome of adult patients infected with TBEV, in comparison to a control group of healthy individuals. Liquid chromatography tandem mass spectrometry (LC-MS) was employed to monitor metabolic and proteomic alternations throughout the progression of the disease, significant physiological changes associated with different stages of the disease were identified. A total of 44 proteins and 115 metabolites exhibited significantly alternations in the sera of patients diagnosed with TBE. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses of these metabolites and proteins revealed differential enrichment of genes associated with the extracellular matrix, complement binding, hemostasis, lipid metabolism, and amino acid metabolism between TBE patients and healthy controls. We gained valuable understanding of the specific metabolites implicated in the host's responses to TBE, establishing a basis for further research on TBE disease. SIGNIFICANCE: The current investigation revealed a comprehensive and systematic differences on TBE using LC-MS platform from human serum samples of TBE patients and healthy individuals providing the immune response to the invasion of TBE.

Mast cells in the autonomic nervous system and potential role in disorders with dysautonomia and neuroinflammation

Mast cells (MC) are ubiquitous in the body, and they are critical for not only in allergic diseases but also in immunity and inflammation, including having potential involvement in the pathophysiology of dysautonomias and neuroinflammatory disorders. MC are located perivascularly close to nerve endings and sites such as the carotid bodies, heart, hypothalamus, the pineal gland, and the adrenal gland that would allow them not only to regulate but also to be affected by the autonomic nervous system (ANS). MC are stimulated not only by allergens but also many other triggers including some from the ANS that can affect MC release of neurosensitizing, proinflammatory, and vasoactive mediators. Hence, MC may be able to regulate homeostatic functions that seem to be dysfunctional in many conditions, such as postural orthostatic tachycardia syndrome, autism spectrum disorder, myalgic encephalomyelitis/chronic fatigue syndrome, and Long-COVID syndrome. The evidence indicates that there is a possible association between these conditions and diseases associated with MC activation. There is no effective treatment for any form of these conditions other than minimizing symptoms. Given the many ways MC could be activated and the numerous mediators released, it would be important to develop ways to inhibit stimulation of MC and the release of ANS-relevant mediators.

The Influence of Microglia on Neuroplasticity and Long-Term Cognitive Sequelae in Long COVID: Impacts on Brain Development and Beyond

Microglial cells, the immune cells of the central nervous system, are key elements regulating brain development and brain health. These cells are fully responsive to stressors, microenvironmental alterations and are actively involved in the construction of neural circuits in children and the ability to undergo full experience-dependent plasticity in adults. Since neuroinflammation is a known key element in the pathogenesis of COVID-19, one might expect the dysregulation of microglial function to severely impact both functional and structural plasticity, leading to the cognitive sequelae that appear in the pathogenesis of Long COVID. Therefore, understanding this complex scenario is mandatory for establishing the possible molecular mechanisms related to these symptoms. In the present review, we will discuss Long COVID and its association with reduced levels of BDNF, altered crosstalk between circulating immune cells and microglia, increased levels of inflammasomes, cytokines and chemokines, as well as the alterations in signaling pathways that impact neural synaptic remodeling and plasticity, such as fractalkines, the complement system, the expression of SIRPα and CD47 molecules and altered matrix remodeling. Together, these complex mechanisms may help us understand consequences of Long COVID for brain development and its association with altered brain plasticity, impacting learning disabilities, neurodevelopmental disorders, as well as cognitive decline in adults.

Plant-derived compounds as potential leads for new drug development targeting COVID-19

COVID-19, which was first identified in 2019 in Wuhan, China, is a respiratory illness caused by a virus called severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Although some patients infected with COVID-19 can remain asymptomatic, most experience a range of symptoms that can be mild to severe. Common symptoms include fever, cough, shortness of breath, fatigue, loss of taste or smell and muscle aches. In severe cases, complications can arise including pneumonia, acute respiratory distress syndrome, organ failure and even death, particularly in older adults or individuals with underlying health conditions. Treatments for COVID-19 include remdesivir, which has been authorised for emergency use in some countries, and dexamethasone, a corticosteroid used to reduce inflammation in severe cases. Biological drugs including monoclonal antibodies, such as casirivimab and imdevimab, have also been authorised for emergency use in certain situations. While these treatments have improved the outcome for many patients, there is still an urgent need for new treatments. Medicinal plants have long served as a valuable source of new drug leads and may serve as a valuable resource in the development of COVID-19 treatments due to their broad-spectrum antiviral activity. To date, various medicinal plant extracts have been studied for their cellular and molecular interactions, with some demonstrating anti-SARS-CoV-2 activity in vitro. This review explores the evaluation and potential therapeutic applications of these plants against SARS-CoV-2. This review summarises the latest evidence on the activity of different plant extracts and their isolated bioactive compounds against SARS-CoV-2, with a focus on the application of plant-derived compounds in animal models and in human studies.

Role of the SARS-CoV-2 Virus in Brain Cells

COVID-19, caused by the SARS-CoV-2 virus, can have neurological effects, including cognitive symptoms like brain fog and memory problems. Research on the neurological effects of COVID-19 is ongoing, and factors such as inflammation, disrupted blood flow, and damage to blood vessels may contribute to cognitive symptoms. Notably, some authors and existing evidence suggest that the SARS-CoV-2 virus can enter the central nervous system through different routes, including the olfactory nerve and the bloodstream. COVID-19 infection has been associated with neurological symptoms such as altered consciousness, headaches, dizziness, and mental disorders. The exact mechanisms and impact on memory formation and brain shrinkage are still being studied. This review will focus on pathways such as the olfactory nerve and blood-brain barrier disruption, and it will then highlight the interactions of the virus with different cell types in the brain, namely neurons, astrocytes, oligodendrocytes, and microglia.

COVID-19 and the brain: understanding the pathogenesis and consequences of neurological damage

SARS-CoV-2 has been known remarkably since December 2019 as a strain of pathogenic coronavirus. Starting from the earlier stages of the COVID-19 pandemic until now, we have witnessed many cases of neurological damage caused by SARS-CoV-2. There are many studies and research conducted on COVID-19-positive-patients that have found brain-related abnormalities with clear neurological symptoms, ranging from simple headaches to life-threatening strokes. For treating neurological damage, knowing the actual pathway or mechanism of causing brain damage via SARS-CoV-2 is very important. For this reason, we have tried to explain the possible pathways of brain damage due to SARS-CoV-2 with mechanisms and illustrations. The SARS-CoV-2 virus enters the human body by binding to specific ACE2 receptors in the targeted cells, which are present in the glial cells and CNS neurons of the human brain. It is found that direct and indirect infections with SARS-CoV-2 in the brain result in endothelial cell death, which alters the BBB tight junctions. These probable alterations can be the reason for the excessive transmission and pathogenicity of SARS-CoV-2 in the human brain. In this precise review, we have tried to demonstrate the neurological symptoms in the case of COVID-19-positive-patients and the possible mechanisms of neurological damage, along with the treatment options for brain-related abnormalities. Knowing the transmission mechanism of SARS-CoV-2 in the human brain can assist us in generating novel treatments associated with neuroinflammation in other brain diseases.

Identification of Factors Associated with Mortality in the Elderly Population with SARS-CoV-2 Infection: Results from a Longitudinal Observational Study from Romania

The progression of SARS-CoV-2 infection has been linked to a hospitalization rate of 20%. The susceptibility of SARS-CoV-2 infection increases with age, resulting in severe and atypical clinical forms of the disease. The severity of SARS-CoV-2 infection in the elderly population can be attributed to several factors, including the overexpression of angiotensin-converting enzyme 2 (ACE2) receptors, immunosenescence, and alterations in the intestinal microbiota that facilitate the cytokine storm. In light of these observations, we conducted a retrospective analysis based on prospectively collected data between 23 December 2021 and 30 April 2022 (the fourth wave of SARS-CoV-2 infection). We analyzed patients aged over 60 years who were hospitalized in a county hospital in Romania. The primary objective of our study was to assess the risk factors for an unfavorable outcome, while the secondary objective was to assess the clinical and baseline characteristics of the enrolled patients. We included 287 cases with a complete electronic medical record from this available cohort of patients. We aimed to retrospectively evaluate a group of 127 patients that progressed, unfortunately, toward an unfavorable outcome versus 160 patients with a favorable outcome. We used the Combined Ordinal Scale of Severity that combines the WHO ordinal scale and the degrees of inflammation to assess the severity of the patients at the time of the initial assessment. The age group between 70 and 79 years had the highest percentage, accounting for 48.0%-61 patients, of the deceased patients. We noted statistically significant differences between groups related to other cardiovascular diseases, nutritional status, hematological diseases, other neurological/mental or digestive disorders, and other comorbidities. Regarding the nutritional status of the patients, there was a statistically significant unfavorable outcome for all the age groups and the patients with a BMI > 30 kg/m2, p = 0.004. The presence of these factors was associated with an unfavorable outcome. Our results indicate that with the presence of cough, there was a statistically significant favorable outcome in the age group over 80 years, p ≤ 0.049. In terms of the presence of dyspnea in all groups of patients, it was associated with an unfavorable outcome, p ≤ 0.001. In our study, we analyzed laboratory test results to assess the level of inflammation across various WHO categories, focusing on the outcome groups determined by the average values of specific biomarkers. Our findings show that, with the exception of IL-6, all other biomarkers tend to rise progressively with the severity of the disease. Moreover, these biomarkers are significantly higher in patients experiencing adverse outcomes. The differences among severity categories and the outcome group are highly significant (p-values < 0.001). CART algorithm revealed a specific cut-off point for the WHO ordinal scale of 4 to stand out as an important reference value for patients at a high risk of developing critical forms of COVID-19. The high death rate can be attributed to proinflammatory status, hormonal changes, nutritional and vitamin D deficiencies, comorbidities, and atypical clinical pictures.

Regulation of Inflammation by IRAK-M Pathway Can Be Associated with nAchRalpha7 Activation and COVID-19

In spite of the vaccine development and its importance, the SARS-CoV-2 pandemic is still impacting the world. It is known that the COVID-19 severity is related to the cytokine storm phenomenon, being inflammation a common disease feature. The nicotinic cholinergic system has been widely associated with COVID-19 since it plays a protective role in inflammation via nicotinic receptor alpha 7 (nAchRalpha7). In addition, SARS-CoV-2 spike protein (Spro) subunits can interact with nAchRalpha7. Moreover, Spro causes toll-like receptor (TLR) activation, leading to pro- and anti-inflammatory pathways. The increase and maturation of the IL-1 receptor-associated kinase (IRAK) family are mediated by activation of membrane receptors, such as TLRs. IRAK-M, a member of this family, is responsible for negatively regulating the activity of other active IRAKs. In addition, IRAK-M can regulate microglia phenotype by specific protein expression. Furthermore, there exists an antagonist influence of SARS-CoV-2 Spro and the cholinergic system action on the IRAK-M pathway and microglia phenotype. We discuss the overexpression and suppression of IRAK-M in inflammatory cell response to inflammation in SARS-CoV-2 infection when the cholinergic system is constantly activated via nAchRalpha7.

Cerebrospinal fluid metabolomic and proteomic characterization of neurologic post-acute sequelae of SARS-CoV-2 infection

The mechanism by which SARS-CoV-2 causes neurological post-acute sequelae of SARS-CoV-2 (neuro-PASC) remains unclear. Herein, we conducted proteomic and metabolomic analyses of cerebrospinal fluid (CSF) samples from 21 neuro-PASC patients, 45 healthy volunteers, and 26 inflammatory neurological diseases patients. Our data showed 69 differentially expressed metabolites and six differentially expressed proteins between neuro-PASC patients and healthy individuals. Elevated sphinganine and ST1A1, sphingolipid metabolism disorder, and attenuated inflammatory responses may contribute to the occurrence of neuro-PASC, whereas decreased levels of 7,8-dihydropterin and activation of steroid hormone biosynthesis may play a role in the repair process. Additionally, a biomarker cohort consisting of sphinganine, 7,8-dihydroneopterin, and ST1A1 was preliminarily demonstrated to have high value in diagnosing neuro-PASC. In summary, our study represents the first attempt to integrate the diagnostic benefits of CSF with the methodological advantages of multi-omics, thereby offering valuable insights into the pathogenesis of neuro-PASC and facilitating the work of neuroscientists in disclosing different neurological dimensions associated with COVID-19.

Impact of COVID-19 on Anxiety and Depression - Biopsychosocial Factors

Anxiety and depression are prevalent mental disorders around the world. The etiology of both diseases is multifactorial, involving biological and psychological issues. The COVID-19 pandemic settled in 2020 and culminated in several changes in the routine of individuals around the world, affecting mental health. People infected with COVID-19 are at greater risk of developing anxiety and depression, and individuals previously affected by these disorders have worsened the condition. In addition, individuals diagnosed with anxiety or depression before being affected by COVID-19 developed the severe illness at higher rates than individuals without mental disorders. This harmful cycle involves several mechanisms, including systemic hyper-inflammation and neuroinflammation. Furthermore, the context of the pandemic and some previous psychosocial factors can aggravate or trigger anxiety and depression. Disorders are also risks for a more severe picture of COVID-19. This review discusses research on a scientific basis, which brings evidence on biopsychosocial factors from COVID-19 and the context of the pandemic involved in anxiety and depression disorders.

Relationship between COVID-19 and Neurological Disorder

Abstract:

The COVID-19 pandemic has resulted in a socially isolating way of life, and dementia patients are among those who are most affected. Lockdown procedures and the inability to monitor illnesses have led to a rapid decline in cognitive function in these individuals, with neuropsychiatric symptoms, such as agitation, delirium, and impaired motor performance being prevalent. However, the use of antipsychotics in treating these symptoms can increase the risk of death during COVID-19. Effective pain therapy can be used as an alternative to reduce or avoid the use of antipsychotics, given the consistent relationship between agitation and pain in dementia patients. The importance of properly assessing and managing pain in dementia patients is highlighted. Additionally, the article discusses how COVID-19 can affect brain health through inflammation, blood clotting, and blood vessel damage, leading to potential long-term effects on cognitive function. Healthcare professionals must be aware of the increased risk of neuropsychiatric symptoms in dementia patients during the pandemic and prioritize pain management as a viable alternative to antipsychotics. Proper care and attention are necessary to prevent cognitive decline and potential long-term effects on brain health in these vulnerable individuals.

Risk factors of Omicron variant associated acute encephalitis/encephalopathy in children

BACKGROUND

Outbreak of Omicron BA.2 in Taiwan led to an increased number of acute encephalitis/encephalopathy cases in children and several fatal cases drew public attention. In pre-Omicron period, pediatric cases of COVID-19-associated acute encephalitis have been reported and during Omicron epidemic, febrile convulsions, encephalitis were mentioned more frequently. The outcome of patients with neurological complications was worse. However, few studies investigated the risk factors, pathophysiology and prognosis of COVID-19-associated encephalitis/encephalopathy. Here, we describe the presentation of pediatric cases of COVID-19-associated acute encephalitis/encephalopathy and explore the associated risk factors.

METHODS

Pediatric patients with confirmed SARS-CoV-2 infections were prospectively enrolled at admission at Chang Gung Memorial Hospital between April and August 2022. Patients were categorized into groups of acute encephalitis/encephalopathy, febrile convulsions or mild disease. Demographic descriptions, clinical manifestations and laboratory data were collected.

RESULTS

Of 288 acute COVID-19 patients, there were 38 (13.2%) acute encephalitis/encephalopathy, 40 (13.9%) febrile convulsions, and 210 (72.9%) mild disease. Among acute encephalitis/encephalopathy group, the mean age was 68.3 ± 45.0 months. The common neurological symptoms were lethargy (65.8%), seizures (52.6%), and impaired consciousness (34.2%). Over 3 years old (adjusted odds ratio [aOR]: 7.57, p < 0.001), absolute neutrophil count ≥3150/μL (aOR: 5.46, p = 0.008), and procalcitonin ≥0.5 ng/mL (aOR: 4.32, p = 0.021) were independent factors for acute encephalitis/encephalopathy.

CONCLUSIONS

Most cases of COVID-19-associated acute encephalitis/encephalopathy showed no evidence of direct viral invasion but associations with older age, increased peripheral neutrophil, and serum procalcitonin. These findings may imply the neutrophil-mediated systemic inflammatory response plays an important role on central nerve system, leading to cerebral dysfunction.

Nanofibrous Membrane Promotes and Sustains Vascular Endothelial Barrier Function

The vascular endothelium serves as a physical barrier between the circulating blood and surrounding tissue and acts as a critical regulator of various physiological processes. In vitro models involving vasculature rely on the maintenance of the endothelial barrier function. In this study, we fabricated 2D aligned nanofibrous membranes with distinct pore sizes via electrospinning and investigated the effect of membrane pore size on endothelial barrier function. Our results demonstrated that the use of the nanofibrous membranes promoted the formation of a tight vascular endothelium and sustained barrier function for over one month in comparison with conventional transwell setups. Moreover, the examination of the nucleocytoplasmic localization of yes-associated protein (YAP) in the endothelial cells indicated that nanofibrous membrane promoted YAP expression and its nuclear localization, critical to endothelial barrier function. Furthermore, the comparison of permeability between random and aligned nanofibrous membranes underscored the importance of pore size in preserving barrier function. Our findings offer a valuable strategy for creating more physiologically relevant in vitro vascular models and contribute to the understanding of endothelial barrier formation and maintenance mechanisms.

Effects of COVID-19 on cognition and brain health

COVID-19 is associated with a range of neurological, cognitive, and mental health symptoms both acutely and chronically that can persist for many months after infection in people with long-COVID syndrome. Investigations of cognitive function and neuroimaging have begun to elucidate the nature of some of these symptoms. They reveal that, although cognitive deficits may be related to brain imaging abnormalities in some people, symptoms can also occur in the absence of objective cognitive deficits or neuroimaging changes. Furthermore, cognitive impairment may be detected even in asymptomatic individuals. We consider the evidence regarding symptoms, cognitive deficits, and neuroimaging, as well as their possible underlying mechanisms.

Recombinant SARS-CoV-2 Spike Protein and Its Receptor Binding Domain Stimulate Release of Different Pro-Inflammatory Mediators via Activation of Distinct Receptors on Human Microglia Cells

SARS-CoV-2 infects cells via its spike (S) protein binding to its surface receptor angiotensin converting enzyme 2 (ACE2) on target cells and results in acute symptoms involving especially the lungs known as COVID-19. However, increasing evidence indicates that SARS-CoV-2 infection produces neuroinflammation associated with neurological, neuropsychiatric, and cognitive symptoms persists well past the resolution of the infection, known as post-COVID-19 sequalae or long-COVID. The neuroimmune mechanism(s) involved in long-COVID have not been adequately characterized. In this study, we show that recombinant SARS-CoV-2 full-length S protein stimulates release of pro-inflammatory IL-1b, CXCL8, IL-6, and MMP-9 from cultured human microglia via TLR4 receptor activation. Instead, recombinant receptor-binding domain (RBD) stimulates release of TNF-α, IL-18, and S100B via ACE2 signaling. These results provide evidence that SARS-CoV-2 spike protein contributes to neuroinflammation through different mechanisms that may be involved in CNS pathologies associated with long-COVID.

Serum of COVID-19 patients changes neuroinflammation and mitochondrial homeostasis markers in hippocampus of aged rats

Patients affected by COVID-19 present mostly with respiratory symptoms but acute neurological symptoms are also commonly observed. Furthermore, a considerable number of individuals develop persistent and often remitting symptoms months after infection, characterizing the condition called long-COVID. Since the pathophysiology of acute and persistent neurological manifestations is not fully established, we evaluated the expression of different genes in hippocampal slices of aged rats exposed to the serum of a post-COVID (sPC) individual and to the serum of patients infected by SARS-CoV-2 [Zeta (sZeta) and Gamma (sGamma) variants]. The expression of proteins related to inflammatory process, redox homeostasis, mitochondrial quality control and glial reactivity was determined. Our data show that the exposure to sPC, sZeta and sGamma differentially altered the mRNA levels of most inflammatory proteins and reduced those of antioxidant response markers in rat hippocampus. Furthermore, a decrease in the expression of mitochondrial biogenesis genes was induced by all serum samples, whereas a reduction in mitochondrial dynamics was only caused by sPC. Regarding the glial reactivity, S100B expression was modified by sPC and sZeta. These findings demonstrate that changes in the inflammatory response and a reduction of mitochondrial biogenesis and dynamics may contribute to the neurological damage observed in COVID-19 patients.

Clinical Potential of Immunotherapies in Subarachnoid Hemorrhage Treatment: Mechanistic Dissection of Innate and Adaptive Immune Responses

Subarachnoid hemorrhage (SAH), classified as a medical emergency, is a devastating and severe subtype of stroke. SAH induces an immune response, which further triggers brain injury; however, the underlying mechanisms need to be further elucidated. The current research is predominantly focused on the production of specific subtypes of immune cells, especially innate immune cells, post-SAH onset. Increasing evidence suggests the critical role of immune responses in SAH pathophysiology; however, studies on the role and clinical significance of adaptive immunity post-SAH are limited. In this present study, we briefly review the mechanistic dissection of innate and adaptive immune responses post-SAH. Additionally, we summarized the experimental studies and clinical trials of immunotherapies for SAH treatment, which may form the basis for the development of improved therapeutic approaches for the clinical management of SAH in the future.

Central nervous system complications in SARS-CoV-2-infected patients

OBJECTIVE

To investigate the clinical manifestations, treatment and prognosis of COVID-19-associated central nervous system (CNS) complications.

METHODS

In this single-centre observation study, we recruited patients with COVID-19-associated CNS complications at the neurology inpatient department of the Eighth Affiliated Hospital, Sun Yat-Sen University (Futian, Shenzhen) from Dec 2022 to Feb 2023. Patients were analysed for demographics, clinical manifestations, cerebrospinal fluid properties, electroencephalographic features, neuroimaging characteristics, and treatment outcome. All patients were followed-up at 1 and 2 months after discharge until Apr 2023.

RESULTS

Of the 12 patients with COVID-19-associated CNS complications, the CNS symptoms occur between 0 days and 4 weeks after SARS-CoV-2 infection. The most common CNS symptoms were memory deficits (4/12, 33%), Unresponsiveness (4/12, 33%), mental and behavioural disorders (4/12, 33%). Seven of 12 cases can be categorized as probable SARS-CoV-2 encephalitis, and 5 cases can be described as brainstem encephalitis, acute disseminated encephalomyelitis, optic neuritis, multiple sclerosis or tremor probably associated with SARS-CoV-2 infection. Six patients received antiviral therapy, and 11 patients received glucocorticoid therapy, of which 3 patients received human immunoglobulin synchronously. Nine patients recovered well, two patients had residual neurological dysfunction, and one patient passed away from complications associated with tumor.

CONCLUSION

In this observational study, we found that the inflammatory or immune-related complications were relatively common manifestations of COVID-19-associated CNS complications, including different phenotypes of encephalitis and CNS inflammatory demyelinating diseases. Most patients recovered well, but a few patients had significant neurological dysfunctions remaining.

Modelling and analysis of the complement system signalling pathways: roles of C3, C5a and pro-inflammatory cytokines in SARS-CoV-2 infection

The complement system is an essential part of innate immunity. It is activated by invading pathogens causing inflammation, opsonization, and lysis via complement anaphylatoxins, complement opsonin's and membrane attack complex (MAC), respectively. However, in SARS-CoV-2 infection overactivation of complement system is causing cytokine storm leading to multiple organs damage. In this study, the René Thomas kinetic logic approach was used for the development of biological regulatory network (BRN) to model SARS-CoV-2 mediated complement system signalling pathways. Betweenness centrality analysis in cytoscape was adopted for the selection of the most biologically plausible states in state graph. Among the model results, in strongly connected components (SCCs) pro-inflammatory cytokines (PICyts) oscillatory behaviour between recurrent generation and downregulation was found as the main feature of SARS-CoV-2 infection. Diversion of trajectories from the SCCs leading toward hyper-inflammatory response was found in agreement with in vivo studies that overactive innate immunity response caused PICyts storm during SARS-CoV-2 infection. The complex of negative regulators FI, CR1 and DAF in the inhibition of complement peptide (C5a) and PICyts was found desirable to increase immune responses. In modelling role of MAC and PICyts in lowering of SARS-CoV-2 titre was found coherent with experimental studies. Intervention in upregulation of C5a and PICyts by C3 was found helpful in back-and-forth variation of signalling pattern linked with the levels of PICyts. Moreover, intervention in upregulation of PICyts by C5a was found productive in downregulation of all activating factors in the normal SCCs. However, the computational model predictions require experimental studies to be validated by exploring the activation role of C3 and C5a which could change levels of PICyts at various phases of SARS-CoV-2 infection.

Brain Renin-Angiotensin System: From Physiology to Pathology in Neuronal Complications Induced by SARS-CoV-2

Angiotensin-converting enzyme 2 (ACE2), a key enzyme in the renin-angiotensin system (RAS), is expressed in various tissues and organs, including the central nervous system (CNS). The spike protein of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for coronavirus disease-2019 (COVID-19), binds to ACE2, which raises concerns about the potential for viral infection in the CNS. There are numerous reports suggesting a link between SARS-CoV-2 infection and neurological manifestations. This study aimed to present an updated review of the role of brain RAS components, especially ACE2, in neurological complications induced by SARS-CoV-2 infection. Several routes of SARS-CoV-2 entry into the brain have been proposed. Because an anosmia condition appeared broadly in COVID-19 patients, the olfactory nerve route was suggested as an early pathway for SARS-CoV-2 entry into the brain. In addition, a hematogenous route via disintegrations in the blood-brain barrier following an increase in systemic cytokine and chemokine levels and retrograde axonal transport, especially via the vagus nerve innervating lungs, have been described. Common nonspecific neurological symptoms in COVID-19 patients are myalgia, headache, anosmia, and dysgeusia. However, more severe outcomes include cerebrovascular diseases, cognitive impairment, anxiety, encephalopathy, and stroke. Alterations in brain RAS components such as angiotensin II (Ang II) and ACE2 mediate neurological manifestations of SARS-CoV-2 infection, at least in part. Downregulation of ACE2 due to SARS-CoV-2 infection, followed by an increase in Ang II levels, leads to hyperinflammation and oxidative stress, which in turn accelerates neurodegeneration in the brain. Furthermore, ACE2 downregulation in the hypothalamus induces stress and anxiety responses by increasing corticotropin-releasing hormone. SARS-CoV-2 infection may also dysregulate the CNS neurotransmission, leading to neurological complications observed in severe cases of COVID-19. It can be concluded that the neurological manifestations of COVID-19 may be partially associated with changes in brain RAS components.

SARS-CoV-2 drives NLRP3 inflammasome activation in human microglia through spike protein

Coronavirus disease-2019 (COVID-19) is primarily a respiratory disease, however, an increasing number of reports indicate that SARS-CoV-2 infection can also cause severe neurological manifestations, including precipitating cases of probable Parkinson's disease. As microglial NLRP3 inflammasome activation is a major driver of neurodegeneration, here we interrogated whether SARS-CoV-2 can promote microglial NLRP3 inflammasome activation. Using SARS-CoV-2 infection of transgenic mice expressing human angiotensin-converting enzyme 2 (hACE2) as a COVID-19 pre-clinical model, we established the presence of virus in the brain together with microglial activation and NLRP3 inflammasome upregulation in comparison to uninfected mice. Next, utilising a model of human monocyte-derived microglia, we identified that SARS-CoV-2 isolates can bind and enter human microglia in the absence of viral replication. This interaction of virus and microglia directly induced robust inflammasome activation, even in the absence of another priming signal. Mechanistically, we demonstrated that purified SARS-CoV-2 spike glycoprotein activated the NLRP3 inflammasome in LPS-primed microglia, in a ACE2-dependent manner. Spike protein also could prime the inflammasome in microglia through NF-κB signalling, allowing for activation through either ATP, nigericin or α-synuclein. Notably, SARS-CoV-2 and spike protein-mediated microglial inflammasome activation was significantly enhanced in the presence of α-synuclein fibrils and was entirely ablated by NLRP3-inhibition. Finally, we demonstrate SARS-CoV-2 infected hACE2 mice treated orally post-infection with the NLRP3 inhibitory drug MCC950, have significantly reduced microglial inflammasome activation, and increased survival in comparison with untreated SARS-CoV-2 infected mice. These results support a possible mechanism of microglial innate immune activation by SARS-CoV-2, which could explain the increased vulnerability to developing neurological symptoms akin to Parkinson's disease in COVID-19 infected individuals, and a potential therapeutic avenue for intervention.

Correlation of covid-19 and Guillain-Barré syndrome: A Mechanistic Perspective

Aims

Coronaviruses, SARS-CoV-2 particles are spherical and have proteins called spikes that stick out on the surface. COVID-19 most commonly affects the respiratory system, but various clinical manifestations on coronavirus have revealed their potential neurotropism. The neuroinvasive affinity of Coronavirus infections has been reported nearly for all the β Coronavirus infections, including MERS-CoV, SARS-CoV, HCoV-OC43 and HEV. Coronavirus invasion occurs through hypoxia injury, immune injury, ACE2, and direct infection. The pathophysiology of SARS-CoV-2 and other human Coronaviruses reveals the possible mechanisms of neurodegeneration.

Methods

A systematic literature review carried out from various search engines like Scopus, PubMed, Medline, and Elsevier for investigating the therapeutic perspective of association between Covid-19 and Guillain-Barré syndrome.

Results

SARS-CoV-2 uses angiotensin-converting enzyme 2 as its entry receptor and enters the central nervous system through a Blood-brain barrier constituted of inflammatory mediators, direct infection of the endothelial cells, or endothelial injury. Guillain-Barré syndrome is an autoimmune disease that injures and attacks the nerves in the peripheral nervous system. Studies suggest that the virus can infect peripheral neurons to cause direct damage through various mechanisms, including direct damage by cytokine-related injury, ACE2 receptors, and the sequelae of hypoxia.

Conclusion

we have discussed the possible mechanisms between neuroinvasion of SARs-cov2 and Guillain-barre syndrome.

Is Guillain-Barre syndrome following chickenpox a parainfectious disease? A case report and literature review

BACKGROUND

Polyradiculoneuropathy following infection with varicella zoster virus (VZV) is rare and most of the time, happens in the context of reactivation of latent VZV. We report a case of acute polyradiculoneuropathy following primary infection with VZV marked by atypical clinical features raising the hypothesis of a para-infectious disease.

CASE PRESENTATION

We describe a 43-years-old male who developed ataxia, dysphagia, dysphonia, and oculomotor disorders (vertical binocular diplopia and bilateral ptosis) followed by quadriplegia with areflexia which occurred 4 days later. The patient had a history of varicella that occurred 10 days before the onset of these symptoms. Nerve conduction study revealed features consistent with an acute motor-sensory axonal neuropathy (AMSAN). Anti-ganglioside antibodies were negative. Based on clinical presentation and ancillary examination, we retain the Miller Fisher/Guillain-Barré overlap syndrome diagnosis. The patient was treated with high doses of methylprednisolone but the evolution of the disease was nevertheless marked by a complete recovery six weeks after onset of symptoms.

CONCLUSION

GBS following varicella is a rare but severe disease occurring most often in adults and marked by greater involvement of the cranial nerves. Its clinical features suggest that it is a para-infectious disease. Antiviral therapy has no effect on the course of the disease but its administration within the first 24 h after the onset of chickenpox in adults can prevent its occurrence.

The viral hypothesis in Alzheimer's disease: SARS-CoV-2 on the cusp

Increasing evidence highlights that infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has long-term effects on cognitive function, which may cause neurodegenerative diseases like Alzheimer's disease (AD) in the future. We performed an analysis of a possible link between SARS-CoV-2 infection and AD risk and proposed several hypotheses for its possible mechanism, including systemic inflammation, neuroinflammation, vascular endothelial injury, direct viral infection, and abnormal amyloid precursor protein metabolism. The purpose of this review is to highlight the impact of infection with SASR-CoV-2 on the future risk of AD, to provide recommendations on medical strategies during the pandemic, and to propose strategies to address the risk of AD induced by SASR-CoV-2. We call for the establishment of a follow-up system for survivors to help researchers better understand the occurrence, natural history, and optimal management of SARS-CoV-2-related AD and prepare for the future.

Neurological manifestations associated with SARS-CoV-2 infection: an updated review

SARS-CoV-2 is a single-stranded RNA virus that belongs to the group of seven coronaviruses that affect humans, and its infection causes the COVID-19 disease. The association between the COVID-19 condition and risk factors of neurological manifestations is unclear to date. This review aims to update the main neurological manifestations associated with SARS-CoV-2 disease. First, we present the hypothesis of the neuroinvasion mechanisms of SARS-CoV-2. Then, we discuss the possible symptoms related to patients with COVID-19 infection in the central and peripheral nervous systems, followed by the perspectives of diagnosis and treatment of possible neurological manifesta-tions. The hypothesis of the neuroinvasion mechanism includes direct routes, as the virus crosses the blood-brain barrier or the ACE2 receptor pathway role, and indirect pathways, such as malfunctions of the immune system and vascular system dysregulation. Various studies report COVID-19 consequences, such as neuroanatomic alterations and cognitive impairment, besides peripheral condi-tions, such as anosmia, ageusia, and Guillain Barré Syndrome. However, the het-erogeneity of the studies about neurologic damage in patients after COVID-19 infection precludes any generalization of current findings. Finally, new studies are necessary to understand the adequate diagnosis, therapeutic method of early treatment, and risk group of patients for neurological manifestations of COVID-19 post-infection.

Encephalitis Associated With SARS-CoV-2 Infection in a Child With Chiari Malformation Type I

BACKGROUND/AIM

There is increasing evidence that patients infected with SARS-CoV-2 develop neurological manifestations such as encephalitis. The purpose of this article was to present a case of viral encephalitis associated with SARS-CoV-2 in a 14-year-old child with Chiari malformation type I.

CASE REPORT

The patient manifested frontal headache, nausea, vomiting, skin pallor, right side Babinski sign and was diagnosed with Chiari malformation type I. He was admitted with generalized seizures and suspected encephalitis. Brain inflammation and viral RNA in the cerebrospinal fluid suggested SARS-CoV-2 encephalitis. These findings indicate that the SARS-CoV-2 test in CSF of patients with neurological manifestations, confusion, and fever during the COVID-19 pandemic should be carried out even when there is no evidence of respiratory infection. To our knowledge, this presentation of encephalitis associated with COVID-19 has not yet been reported in a patient with a congenital syndrome such as Chiari malformation type I.

CONCLUSION

Further clinical data are needed to determine the complications of encephalitis due to SARS-CoV-2 in patients with Chiari malformation type I to standardize diagnosis and treatment.

Olfactory impairment in COVID-19: Two methods for the assessment of olfactory function

Background

Olfactory impairment is a major symptom of COVID-19. Is it necessary for COVID-19 patients to perform the detection of olfactory function, even how to select the olfactory psychophysical assessment tool.

Methods

Patients infected with SARS-CoV-2 Delta variant were firstly taken into three categories (mild, moderate, and severe) according to the clinical classification. The Odor Stick Identification Test for the Japanese (OSIT-J) and the Simple Olfactory Test were used to assess olfactory function. Moreover, these patients were divided into three groups based on the results of the olfactory degree (euosmia, hyposmia, and dysosmia), too. The statistical analysis of the correlations between olfaction and clinical characteristics of patients were performed.

Results

Our study demonstrated that the elderly men of Han were more susceptible to infected SARS-CoV-2, the clinical symptoms of the COVID-19 patients showed a clear correspondence with the disease type and the degree of olfactory disturbance. Whether or not to vaccinate and whether to complete the whole course of vaccination was closely related to the patient's condition. OSIT-J Test and Simple Test were consistent in our work, indicating that olfactory grading would worsen with the aggravation of symptoms. Furthermore, the OSIT-J method maybe better than Simple Olfactory Test.

Conclusion

The vaccination has an important protective effect on the general population, and vaccination should be vigorously promoted. Moreover, it is necessary for COVID-19 patients to perform the detection of olfactory function, and the easier, faster and less expensive method for determination of olfactory function should be utilized to COVID-19 patients as the vital physical examination.

Imaging and neuropathological findings in patients with Post COVID-19 Neurological Syndrome-A review

Post COVID-19 syndrome is determined as signs and symptoms that appear during or after an infection consistent with SARS-CoV-2 disease, persist for more than 12 weeks and are not explained by an alternative diagnosis. This review presents the neuropathological findings and imaging findings in Post COVID-19 Neurological Syndrome: the focal point is on the manifestations of involvement evident on brain and spine imaging.

SARS-CoV-2 Possible Etiology of Cerebral Venous Thrombosis in a Teenager: Case Report and Review of Literature

Cerebral venous thrombosis in pediatric patient has a varied etiology. The authors present the case of a teenager who, since the debut of SARS-CoV-2 infection, has accused intermittent right side hemicrania, which has become persistent in association with nausea and vomiting since the 5th day of quarantine. She was hospitalized in the 9th day since the debut. Neuroimaging revealed extended venous cerebral thrombosis affecting the right sigmoid sinus, the transverse sinus bilaterally, the confluence of the transverse sinuses and the right internal jugular vein. The evolution was favorable under anticoagulant and symptomatic treatment. Laboratory tests excluded other etiological causes for the cerebral venous thrombosis, thus the authors consider that cerebral thrombosis is a possible complication of SARS-CoV-2 infection in teenagers.

COVID-19 as a Risk Factor for Alzheimer's Disease

Severe acute respiratory disease coronavirus 2 (SARS-CoV-2) is responsible for the coronavirus disease 2019 (COVID-19) pandemic. Although a primarily respiratory disease, recent reports indicate that it also affects the central nervous system (CNS). Over 25% of COVID-19 patients report neurological symptoms such as memory loss, anosmia, hyposmia, confusion, and headaches. The neurological outcomes may be a result of viral entry into the CNS and/or resulting neuroinflammation, both of which underlie an elevated risk for Alzheimer's disease (AD). Herein, we ask: Is COVID-19 a risk factor for AD? To answer, we identify the literature and review mechanisms by which COVID-19-mediated neuroinflammation can contribute to the development of AD, evaluate the effects of acute versus chronic phases of infection, and lastly, discuss potential therapeutics to address the rising rates of COVID-19 neurological sequelae.

Genetic Predisposition to Neurological Complications in Patients with COVID-19

Several studies have identified rare and common genetic variants associated with severe COVID-19, but no study has reported genetic determinants as predisposition factors for neurological complications. In this report, we identified rare/unique structural variants (SVs) implicated in neurological functions in two individuals with neurological manifestations of COVID-19. This report highlights the possible genetic link to the neurological symptoms with COVID-19 and calls for a collective effort to study these cohorts for a possible genetic linkage.

Case report: Bilateral globus pallidus lesions and delayed progressive leukoencephalopathy in COVID-19: Effects of hypoxia alone or combination of hypoxia and inflammation?

Background

The globus pallidus is a highly mitochondria-rich metabolic structure that is particularly sensitive to metabolic disturbances and hypoxia. Symmetric lesions of globus pallidus and delayed diffuse leukoencephalopathy were documented in toxic-metabolic disorders, hypoxia, a neurodegenerative disorder, and mitochondrial encephalopathies. Similar changes are also reported in individuals with active COVID-19 infections with associated hypoxia or critical illness.

Case information

We describe a patient with post-COVID-19 infection who presented with rapid cognitive and neurological decline associated with similar neuroimaging structural changes but without toxic-metabolic changes or hypoxia. Despite multiple non-inflammatory cerebrospinal fluid studies, mechanisms involving post-COVID-19 inflammation and immune dysregulation are suspected, given the unexplained continued decline in the neurological status, lack of concurrent hypoxia or antecedent respiratory difficulties, and after a reasonable exclusion of alternative etiologies. Hypermetabolism of both anteromedial temporal structures and diffuse hypometabolism predominantly in the frontal region on PET scan provided indirect support for possible inflammatory mechanisms after reasonable exclusion of alternative etiologies, such as direct CNS infection, among others. The patient's neurological impairment improved substantially after treatment with pulse steroids, plasmapheresis, and rituximab.

Conclusion

To the best of our knowledge, this is the first report of post-COVID-19 with bilateral symmetric contrast-enhancing necrotic lesions of globus pallidus with delayed diffuse supratentorial leukoencephalopathy with microhemorrhages without concurrent hypoxia or reported preceding symptoms suggestive of hypoxia. We suspect that these inflammatory mechanisms might be triggered by prior COVID-19 exposure/infection. Furthermore, the role of the cross-talk between inflammation and clinically mild or silent hypoxia linked to prior COVID-19 infection cannot be excluded. Awareness of these post-COVID-19 neurological sequelae and their potential pathophysiology among those with no known antecedent significant hypoxia are important for early recognition and treatment.

Spatial Mapping of Genes Implicated in SARS-CoV-2 Neuroinvasion to Dorsolateral Prefrontal Cortex Gray Matter

Introduction

SARS-CoV-2 is the newest beta coronavirus family member to demonstrate neuroinvasive capability in severe cases of infection. Despite much research activity in the SARS-CoV-2/COVID-19 space, the gene-level biology of this phenomenon remains poorly understood. In the present analysis, we leveraged spatial transcriptomics methodologies to examine relevant gene heterogeneity in tissue retrieved from the human prefrontal cortex.

Methods

Expression profiles of genes with established relations to the SARS-CoV-2 neuroinvasion process were spatially resolved in dorsolateral prefrontal cortex tissue (N = 4). Spotplots were generated with mapping to six (6) previously defined gray matter layers.

Results

Docking gene BSG, processing gene CTSB, and viral defense gene LY6E demonstrated similar spatial enrichment. Docking gene ACE2 and transmembrane series proteases involved in spike protein processing were lowly expressed across DLPFC samples. Numerous other findings were obtained.

Conclusion

Efforts to spatially represent expression levels of key SARS-CoV-2 brain infiltration genes remain paltry to date. Understanding the sobering history of beta coronavirus neuroinvasion represents a weak point in viral research. Here we provide the first efforts to characterize a motley of such genes in the dorsolateral prefrontal cortex.

Co-ultramicronized palmitoylethanolamide/luteolin normalizes GABAB-ergic activity and cortical plasticity in long COVID-19 syndrome

OBJECTIVE

Transcranial magnetic stimulation (TMS) studies showed that patients with cognitive dysfunction and fatigue after COVID-19 exhibit impaired cortical GABA_B-ergic activity, as revealed by reduced long-interval intracortical inhibition (LICI). Aim of this study was to test the effects of co-ultramicronized palmitoylethanolamide/luteolin (PEA-LUT), an endocannabinoid-like mediator able to enhance GABA-ergic transmission and to reduce neuroinflammation, on LICI.

METHODS

Thirty-nine patients (26 females, mean age 49.9 ± 11.4 years, mean time from infection 296.7 ± 112.3 days) suffering from persistent cognitive difficulties and fatigue after mild COVID-19 were randomly assigned to receive either PEA-LUT 700 mg + 70 mg or PLACEBO, administered orally bid for eight weeks. The day before (PRE) and at the end of the treatment (POST), they underwent TMS protocols to assess LICI. We further evaluate short-latency afferent inhibition (SAI) and long-term potentiation (LTP)-like cortical plasticity.

RESULTS

Patients treated with PEA-LUT but not with PLACEBO showed a significant increase of LICI and LTP-like cortical plasticity. SAI remained unaffected.

CONCLUSIONS

Eight weeks of treatment with PEA-LUT restore GABA_B activity and cortical plasticity in long Covid patients.

SIGNIFICANCE

This study confirms altered physiology of the motor cortex in long COVID-19 syndrome and indicates PEA-LUT as a candidate for the treatment of this post-viral condition.

C-Reactive Protein (CRP): A Potent Inflammation Biomarker in Psychiatric Disorders

An increasing number of studies have investigated the role of inflammation in psychiatric disorders, by demonstrating how an altered/dysfunctional immunological and inflammatory system may underpin a psychiatric condition. Particularly, several studies specifically investigated the role of a neuroinflammatory biomarker, named C-reactive protein (CRP), in psychiatric disorders. Overall, even though scientific literature so far published still does not appear definitive, CRP is more likely reported to be elevated in several psychiatric disorders, including schizophrenia, mood disorders, anxiety disorders and post-traumatic stress disorder. Moreover, a low-grade inflammation (CRP >3 mg/L) has been more likely observed in a subgroup of patients affected with a more severe psychopathological symptomatology, more treatment resistance and worst clinical mental illness course, strengthening the hypothesis of the need for a different clinical and prognostic characterization based on this concomitant neuroinflammatory predisposition. However, even though further research studies are needed to confirm this preliminary evidence, CRP may represent a potential clinical routine biomarker which could be integrated in the clinical routine practice to better characterize clinical picture and course as well as address clinicians towards a personalized treatment.

Neurological Signs of Postcovid Syndrome

The challenge of postcovid syndrome (PCS) is of great interest due to its wide distribution and variety of clinical signs. The main neurological signs of PCS are discussed. Data on the presumptive mechanisms forming PCS are presented. The potential for using the drug Mexidol to treat patients with PCS is addressed.

First-episode psychotic disorders in the wake of the COVID-19 pandemic: a descriptive review of casereports

OBJECTIVE

Since the onset of COVID-19 pandemic, many case reports and case series dealt with new-onset psychotic disorders in patients either infected with SARS-CoV-2 or thematically linked to the pandemic, but without an infection. Our aim was to provide a comprehensive collection of these reports to illustrate the nature of these psychoses.

METHODS

We conducted a literature search in MEDLINE, Embase, PsycINFO, using search terms regarding first-episode psychotic disorders in the context of corona.

RESULTS

96 case reports or case series covering 146 patients (62 without and 84 with SARS-CoV-2 infection) were found. Compared to patients without infection, patients with infection showed significantly more often visual hallucinations (28.6% vs 8.1%), confusion (36.9% vs 11.3%), an acute onset of illness (88.5% vs 59.6%) and less often depression (13.1% vs 35.5%) and a delusional content related to the pandemic (29.5% vs 78.3%). Both groups had an equally favourable outcome with a duration of psychosis ≤2 weeks in half and full remission in two-thirds of patients. In patients with infection, signs of inflammation were reported in 78.3% and increased CRP in 58.6%. While reports on patients with infection are continuously published, no report about patients without infection was found after July 2020.

CONCLUSION

Cases without infection were considered reactive and originated all from the first wave of the corona pandemic. In cases with infection, inflammation was considered as the main pathogenetic factor but was not found in all patients. Diagnosis was impeded by the overlap of psychosis with delirium.

COVID-19 related acute necrotizing encephalopathy with extremely high interleukin-6 and RANBP2 mutation in a patient with recently immunized inactivated virus vaccine and no pulmonary involvement

Background

We report the first case of COVID-19 associated acute necrotizing encephalopathy (ANE) without pulmonary disease in a patient with an extremely high interleukin-6 (IL-6) level and Ran Binding Protein 2 (RANBP2) mutation.

Case presentation

A 29-year-old woman recently immunized with inactivated viral vaccine—BBIBP32-CorV (Sinopharm) presented with alteration of consciousness. Her body temperature was 37° Celsius, blood pressure 42/31 mmHg, heart rate 130 bpm, respiratory rate 20 per minute, and oxygen saturation 98%. Respiratory examination was unremarkable. Neurological examination revealed stupor but preserved brainstem reflexes. Non-contrast computerized tomography of the brain showed symmetrical hypodense lesions involving bilateral thalami and cerebellar hemispheres characteristic of ANE. No pulmonary infiltration was found on chest radiograph. SARS-CoV-2 was detected by PCR; whole genome sequencing later confirmed the Delta variant. RANBP2 gene analysis revealed heterozygous Thr585Met mutation. Serum IL-6 was 7390 pg/mL. Urine examination showed pyelonephritis. Her clinical course was complicated by seizure, septic shock, acute kidney injury, and acute hepatic failure. She later developed coma and passed away in 6 days.

Conclusions

ANE is caused by cytokine storm leading to necrosis and hemorrhage of the brain. IL-6 was deemed as a prognostic factor and a potential treatment target of ANE in previous studies. RANBP2 missense mutation strongly predisposes this condition by affecting mitochondrial function, viral entry, cytokine signaling, immune response, and blood–brain barrier maintenance. Also, inactivated vaccine has been reported to precipitate massive production of cytokines by antibody dependent enhancement (ADE). The true incidence of COVID-19 associated ANE is not known as were the predictors of its development. We proposed these potential two factors (RANBP2 mutation and ADE) that could participate in the pathogenesis of ANE in COVID-19 apart from SARS-CoV2 infection by itself. Further study is needed to confirm this hypothesis, specifically in the post-vaccination period. Role of RANBP2 mutation and its application in COVID-19 and ANE should be further elaborated.

Pathophysiology and mechanism of long COVID: a comprehensive review

BACKGROUND

After almost 2 years of fighting against SARS-CoV-2 pandemic, the number of patients enduring persistent symptoms long after acute infection is a matter of concern. This set of symptoms was referred to as "long COVID", and it was defined more recently as "Post COVID-19 condition" by the World health Organization (WHO). Although studies have revealed that long COVID can manifest whatever the severity of inaugural illness, the underlying pathophysiology is still enigmatic.

AIM

To conduct a comprehensive review to address the putative pathophysiology underlying the persisting symptoms of long COVID.

METHOD

We searched 11 bibliographic databases (Cochrane Library, JBI EBP Database, Medline, Embase, PsycInfo, CINHAL, Ovid Nursing Database, Journals@Ovid, SciLit, EuropePMC, and CoronaCentral). We selected studies that put forward hypotheses on the pathophysiology, as well as those that encompassed long COVID patients in their research investigation.

RESULTS

A total of 98 articles were included in the systematic review, 54 of which exclusively addressed hypotheses on pathophysiology, while 44 involved COVID patients. Studies that included patients displayed heterogeneity with respect to the severity of initial illness, timing of analysis, or presence of a control group. Although long COVID likely results from long-term organ damage due to acute-phase infection, specific mechanisms following the initial illness could contribute to the later symptoms possibly affecting many organs. As such, autonomic nervous system damage could account for many symptoms without clear evidence of organ damage. Immune dysregulation, auto-immunity, endothelial dysfunction, occult viral persistence, as well as coagulation activation are the main underlying pathophysiological mechanisms so far.

CONCLUSION

Evidence on why persistent symptoms occur is still limited, and available studies are heterogeneous. Apart from long-term organ damage, many hints suggest that specific mechanisms following acute illness could be involved in long COVID symptoms. KEY MESSAGESLong-COVID is a multisystem disease that develops regardless of the initial disease severity. Its clinical spectrum comprises a wide range of symptoms.The mechanisms underlying its pathophysiology are still unclear. Although organ damage from the acute infection phase likely accounts for symptoms, specific long-lasting inflammatory mechanisms have been proposed, as well.Existing studies involving Long-COVID patients are highly heterogeneous, as they include patients with various COVID-19 severity levels and different time frame analysis, as well.

SARS-CoV-2-Induced Amyloidgenesis: Not One, but Three Hypotheses for Cerebral COVID-19 Outcomes

The main neuropathological feature of Alzheimer's disease (AD) is extracellular amyloid deposition in senile plaques, resulting from an imbalance between the production and clearance of amyloid beta peptides. Amyloid deposition is also found around cerebral blood vessels, termed cerebral amyloid angiopathy (CAA), in 90% of AD cases. Although the relationship between these two amyloid disorders is obvious, this does not make CAA a characteristic of AD, as 40% of the non-demented population presents this derangement. AD is predominantly sporadic; therefore, many factors contribute to its genesis. Herein, the starting point for discussion is the COVID-19 pandemic that we are experiencing and how SARS-CoV-2 may be able to, both directly and indirectly, contribute to CAA, with consequences for the outcome and extent of the disease. We highlight the role of astrocytes and endothelial cells in the process of amyloidgenesis, as well as the role of other amyloidgenic proteins, such as fibrinogen and serum amyloid A protein, in addition to the neuronal amyloid precursor protein. We discuss three independent hypotheses that complement each other to explain the cerebrovascular amyloidgenesis that may underlie long-term COVID-19 and new cases of dementia.

Post acute CoViD-19 syndrome (PACS) - Long CoViD

Patients sero-positive for the Systemic Acute Respiratory Syndrome Corona virus2 (SARS-CoV2) virus develop the Corona Virus Disease 2019 (CoViD-19). CoViD-19 may be asymptomatic in some individuals, proffer mild symptoms in other patients, and can be a serious and even lethal disease in a sub-group of the population. The variables that determine the severity of CoViD-19 have not been fully characterized. What is clear is that the patients who survive CoViD-19 return to a state of sero-negativity for SARS-CoV2 generally within 3-5 weeks. However, several cases of repeated infection have been reported, and a large proportion of CoViD-19-recovered patients manifest multi-system and multi-organ symptomatic pathologies several weeks-to-months after resuming sero-negativity for SARS-CoV2. This new pathological condition, originally termed Long Covid, is now recognized as the Post Acute CoViD-19 Syndrome (PACS). The original principal clusters of signs and symptoms of PACS: likelihood of relapse and reinfection, physical fatigue and cognitive slowdown, may actually be broadened to include immune deregulation, cardiovascular disease and coagulation abnormalities. The development and evaluation of new and improved clinical interventions for PACS are critical and timely.

Neuro-Immune Interactions in Severe COVID-19 Infection

SARS-CoV-2 is a new coronavirus that has affected the world since 2019. Interstitial pneumonia is the most common clinical presentation, but additional symptoms have been reported, including neurological manifestations. Severe forms of infection, especially in elderly patients, present as an excessive inflammatory response called "cytokine storm", which can lead to acute respiratory distress syndrome (ARDS), multiorgan failure and death. Little is known about the relationship between symptoms and clinical outcomes or the characteristics of virus-host interactions. The aim of this narrative review is to highlight possible links between neurological involvement and respiratory damage mediated by pathological inflammatory pathways in SARS-CoV-2 infection. We will focus on neuro-immune interactions and age-related immunity decline and discuss some pathological mechanisms that contribute to negative outcomes in COVID-19 patients. Furthermore, we will describe available therapeutic strategies and their effects on COVID-19 neurological symptoms.

Attenuation of relapsing fever neuroborreliosis in mice by IL-17A blockade

Spirochetes of the genus Borrelia can spread to various organs including the central nervous system. The neurological disease manifestations in these bacterial infections are commonly referred as neuroborreliosis. Currently, long-term antibiotic treatment is the only the United States Food and Drug Administration-approved option for those suffering from neuroborreliosis. Using Borrelia hermsii infection in mice, we have previously established a relapsing fever neuroborreliosis model. In this model, we found that the induction of interleukin (IL)-17A signaling plays a major role in the pathogenesis of relapsing fever neuroborreliosis. We show that anti-IL-17A antibody treatment can ameliorate the pathology. Our data suggest that IL-17A blockade may be a therapeutic strategy for controlling relapsing fever neuroborreliosis.

Relapsing fever due to Borrelia hermsii is characterized by recurrent bacteremia episodes. However, infection of B. hermsii, if not treated early, can spread to various organs including the central nervous system (CNS). CNS disease manifestations are commonly referred to as relapsing fever neuroborreliosis (RFNB). In the mouse model of B. hermsii infection, we have previously shown that the development of RFNB requires innate immune cells as well as T cells. Here, we found that prior to the onset of RFNB, an increase in the systemic proinflammatory cytokine response followed by sustained levels of IP-10 concurrent with the CNS disease phase. RNA sequencing analysis of the spinal cord tissue during the disease phase revealed an association of the interleukin (IL)-17 signaling pathway in RFNB. To test a possible role for IL-17 in RFNB, we compared B. hermsii infection in wild-type and IL-17A^−/− mice. Although the onset of bacteremia and protective anti-B. hermsii antibody responses occurred similarly, the blood-brain barrier permeability, proinflammatory cytokine levels, immune cell infiltration in the spinal cord, and RFNB manifestations were significantly diminished in IL-17A^−/− mice compared to wild-type mice. Treatment of B. hermsii-infected wild-type mice with anti-IL-17A antibody ameliorated the severity of spinal cord inflammation, microglial cell activation, and RFNB. These data suggest that the IL-17 signaling pathway plays a major role in the pathogenesis of RFNB, and IL-17A blockade may be a therapeutic modality for controlling neuroborreliosis.