Early postmortem brain MRI findings in COVID-19 non-survivors

Frailty as a Risk Factor for Depression after COVID-19 Hospital Admission

BACKGROUND

This work aims to establish the relationship between depression and epidemiological or imaging variables, frailty, and cognitive status in patients who suffered hospital admission for COVID-19.

METHODS

A longitudinal observational study investigated 72 patients admitted for COVID-19 to a hospital in Spain. Patients were evaluated at discharge and six months later. Clinical, analytical, and imaging variables were collected. A neurocognitive, nutritional, and frailty (FRAIL scale) assessment of the included patients was carried out. The risk of depression was considered for a result above 5 points on the PHQ-9 scale.

RESULTS

The variables that were significantly related to the risk of depression 6 months after admission for COVID-19 were frailty (p = 0.006 for pre-frail and p = 0.001 for frail), small-vessel vascular disease in imaging tests (p = 0.033), vitamin D level (p = 0.006), and taking antidepressants (p = 0.011). Factors that were negatively associated with the presence of depression 6 months after discharge were a higher score on the CAMCOG cognitive scale (p = 0.041) and older age (p = 0.006).

CONCLUSIONS

Frailty worsened the score on the PHQ-9 depression scale in patients who required hospital admission for SARS-CoV-2 infection. It is important to implement prevention measures both for frailty and depression in these patients.

Cerebral microbleeds in patients with COVID-19: is there an inevitable connection?

The COVID-19 pandemic has underscored the critical interplay between systemic infections and neurological complications, notably cerebral microbleeds. This comprehensive review meticulously aggregates and analyses current evidence on cerebral microbleeds' prevalence, pathophysiological underpinnings and clinical implications within COVID-19 cohorts. Our findings reveal a pronounced correlation between cerebral microbleeds and increased severity of COVID-19, emphasizing the role of direct viral effects, inflammatory responses and coagulation disturbances. The documented association between cerebral microbleeds and elevated risks of morbidity and mortality necessitates enhanced neurological surveillance in managing COVID-19 patients. Although variability in study methodologies presents challenges, the cumulative evidence substantiates cerebral microbleeds as a critical illness manifestation rather than mere coincidence. This review calls for harmonization in research methodologies to refine our understanding and guide targeted interventions. Prioritizing the detection and study of neurological outcomes, such as cerebral microbleeds, is imperative for bolstering pandemic response strategies and mitigating the long-term neurological impact on survivors.

New insights into the pathogenesis of SARS-CoV-2 during and after the COVID-19 pandemic

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the respiratory distress condition known as COVID-19. This disease broadly affects several physiological systems, including the gastrointestinal, renal, and central nervous (CNS) systems, significantly influencing the patient's overall quality of life. Additionally, numerous risk factors have been suggested, including gender, body weight, age, metabolic status, renal health, preexisting cardiomyopathies, and inflammatory conditions. Despite advances in understanding the genome and pathophysiological ramifications of COVID-19, its precise origins remain elusive. SARS-CoV-2 interacts with a receptor-binding domain within angiotensin-converting enzyme 2 (ACE2). This receptor is expressed in various organs of different species, including humans, with different abundance. Although COVID-19 has multiorgan manifestations, the main pathologies occur in the lung, including pulmonary fibrosis, respiratory failure, pulmonary embolism, and secondary bacterial pneumonia. In the post-COVID-19 period, different sequelae may occur, which may have various causes, including the direct action of the virus, alteration of the immune response, and metabolic alterations during infection, among others. Recognizing the serious adverse health effects associated with COVID-19, it becomes imperative to comprehensively elucidate and discuss the existing evidence surrounding this viral infection, including those related to the pathophysiological effects of the disease and the subsequent consequences. This review aims to contribute to a comprehensive understanding of the impact of COVID-19 and its long-term effects on human health.

Hippocampal neurometabolic and structural changes from pre-to post-COVID-19: A case-series study

BACKGROUND

Neurological complications of the COVID-19 infection may be caused in part by local neurochemical and structural abnormalities that could not be detected during routine medical examinations. We examined within subject neurometabolic and structural brain alterations from pre-to post-COVID-19 in the hippocampal region of three elderly individuals (aged 63-68 years) who had a COVID-19 infection with mild symptoms. Patients were participating in an interventional study in which they were closely monitored at the time they were diagnosed with COVID-19. Patients 1 and 2 just completed 18-20 resistance training sessions prior to their diagnosis. Patient 3 was assigned to a non-training condition in the same study.

METHODS

Whole brain magnetic resonance imaging (MRI) images and proton magnetic resonance spectroscopy (1H-MRS) of the left hippocampus were collected before and after infection. Structural and spectroscopic imaging measures post-COVID-19 were contrasted to the pre-COVID-19 measures and were compared with values for Minimal Detectable Change at 95% (MDC95) and 90% (MDC90) confidence from a group of six elderly (aged 60-79 years) without COVID-19 that participated in the same study.

RESULTS

After SARS-COV-2 infection, we observed a reduction of glutamate-glutamine (Glx) in Patients 1 and 2 (≥ 42.0%) and elevation of myo-inositol (mIns) and N-acetyl-aspartate (NAA) in Patient 3 (≥ 36.4%); all > MDC90. MRI findings showed increased (Patients 1 and 2) or unchanged (Patient 3) hippocampal volume.

CONCLUSIONS

Overall, findings from this exploratory study suggest that mild COVID-19 infection could be associated with development of local neuroinflammation and reduced glutamate levels in the hippocampus. Our 1H-MRS findings may have clinical value for explaining chronic neurological and psychological complaints in COVID-19 long-haulers.

Insights Into MRI Neuroimaging Patterns of COVID-19 in Children: A Retrospective Comprehensive Analysis

RATIONALE AND OBJECTIVES

Neurological complications associated with coronavirus disease (COVID-19) have been reported in children; however, data on neuroimaging findings remain limited. This study aimed to comprehensively examine neuroimaging patterns of COVID-19 in children and their relationship with clinical outcomes.

MATERIALS AND METHODS

This retrospective cross-sectional study involved reviewing the medical records and MRI scans of 95 children who developed new neurological symptoms within 2-4 weeks of clinical and laboratory confirmation of COVID-19. Patients were categorized into four groups based on guidelines approved by the Centers for Disease Control and Prevention (CDC). Initial brain/spinal MRI was performed. Images were reviewed by three blinded radiologists, and the findings were analyzed and categorized based on the observed patterns in the brain and spinal cord. Follow-up MRI was performed and analyzed to track lesion progression.

RESULTS

Encephalopathy was the most common neurological symptom (50.5%). The most common initial MRI involvement patterns were non-confluent multifocal hyperintense white matter (WM) lesions (36.8%) and ischemia (18.9%). Most patients who underwent follow-up MRI (n = 56) showed complete resolution (69.9%); however, some patients developed encephalomalacia and myelomalacia (23.2% and 7.1%, respectively). Non-confluent hyperintense WM lesions were associated with good outcomes (45.9%, P = 0.014), whereas ischemia and hemorrhage were associated with poor outcomes (44.1%, P < 0.001).

CONCLUSION

This study revealed diverse neuroimaging patterns in pediatric COVID-19 patients. Non-confluent WM lesions were associated with good outcomes, whereas ischemia and hemorrhage were associated with poorer prognoses. Understanding these patterns is crucial for their early detection, accurate diagnosis, and appropriate management.

A Comprehensive Review of the Global Epidemiology, Clinical Management, Socio-Economic Impacts, and National Responses to Long COVID with Future Research Directions

Background: Long COVID, characterized by a persistent symptom spectrum following SARS-CoV-2 infection, poses significant health, social, and economic challenges. This review aims to consolidate knowledge on its epidemiology, clinical features, and underlying mechanisms to guide global responses; Methods: We conducted a literature review, analyzing peer-reviewed articles and reports to gather comprehensive data on long COVID's epidemiology, symptomatology, and management approaches; Results: Our analysis revealed a wide array of long COVID symptoms and risk factors, with notable demographic variability. The current understanding of its pathophysiology suggests a multifactorial origin yet remains partially understood. Emerging diagnostic criteria and potential therapeutic strategies were identified, highlighting advancements in long COVID management; Conclusions: This review highlights the multifaceted nature of long COVID, revealing a broad spectrum of symptoms, diverse risk factors, and the complex interplay of physiological mechanisms underpinning the condition. Long COVID symptoms and disorders will continue to weigh on healthcare systems in years to come. Addressing long COVID requires a holistic management strategy that integrates clinical care, social support, and policy initiatives. The findings underscore the need for increased international cooperation in research and health planning to address the complex challenges of long COVID. There is a call for continued refinement of diagnostic and treatment modalities, emphasizing a multidisciplinary approach to manage the ongoing and evolving impacts of the condition.

Heatstroke Comorbid with SARS-CoV-2 Infection: A Case Report and Literature Review

Background

Hyperthermia and multiple organ dysfunction syndrome (MODS) are the main characteristics of heatstroke and COVID-19. Differentiating between these illnesses is crucial during a summer COVID-19 pandemic, but cases of heatstroke comorbid with COVID-19 are rarely reported.

Case description

We report the first case of heatstroke comorbid with Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection in a 52-year-old male. After receiving intravenous antibiotics, organ protection measures, and treatment for coagulation disorders, his fever and coma resolved. However, he developed dyspnea and cerebral hemorrhage after several days. This patient experienced a multi-pathogen pulmonary infection and an intractable coagulopathy that ultimately resulted in MODS and death.

Conclusion

The combination of heatstroke and SARS-CoV-2 infection exacerbated inflammation, immune abnormalities, and coagulation disorders. The interaction between inflammation and coagulation disturbances contributed to the underlying mechanism in this case, highlighting the importance of early anti-infection, treatment for coagulopathy, immune regulation, and organ protection as crucial interventions.

COVID-19: Unveiling the Neuropsychiatric Maze-From Acute to Long-Term Manifestations

The SARS-CoV-2 virus has spread rapidly despite implementing strategies to reduce its transmission. The disease caused by this virus has been associated with a diverse range of symptoms, including common neurological manifestations such as dysgeusia, anosmia, and myalgias. Additionally, numerous cases of severe neurological complications associated with this disease have been reported, including encephalitis, stroke, seizures, and Guillain-Barré syndrome, among others. Given the high prevalence of neurological manifestations in this disease, the objective of this review is to analyze the mechanisms by which this virus can affect the nervous system, from its direct invasion to aberrant activation of the immune system and other mechanisms involved in the symptoms, including neuropsychiatric manifestations, to gain a better understanding of the disease and thus facilitate the search for effective therapeutic strategies.

Mechanisms of COVID-19-associated olfactory dysfunction

Olfactory dysfunction is one of the most common symptoms of COVID-19. In the first 2 years of the pandemic, it was frequently reported, although its incidence has significantly decreased with the emergence of the Omicron variant, which has since become the dominant viral strain. Nevertheless, many patients continue to suffer from persistent dysosmia and dysgeusia, making COVID-19-associated olfactory dysfunction an ongoing health concern. The proposed pathogenic mechanisms of COVID-19-associated olfactory dysfunction are complex and likely multifactorial. While evidence suggests that infection of sustentacular cells and associated mucosal inflammation may be the culprit of acute, transient smell loss, alterations in other components of the olfactory system (e.g., olfactory receptor neuron dysfunction, olfactory bulb injury and alterations in the olfactory cortex) may lead to persistent, long-term olfactory dysfunction. This review aims to provide a comprehensive summary of the epidemiology, clinical manifestations and current understanding of the pathogenic mechanisms of COVID-19-associated olfactory dysfunction.

On the merits and potential of advanced neuroimaging techniques in COVID-19: A scoping review

Many Coronavirus Disease 2019 (COVID-19) patients are suffering from long-term neuropsychological sequelae. These patients may benefit from a better understanding of the underlying neuropathophysiological mechanisms and identification of potential biomarkers and treatment targets. Structural clinical neuroimaging techniques have limited ability to visualize subtle cerebral abnormalities and to investigate brain function. This scoping review assesses the merits and potential of advanced neuroimaging techniques in COVID-19 using literature including advanced neuroimaging or postmortem analyses in adult COVID-19 patients published from the start of the pandemic until December 2023. Findings were summarized according to distinct categories of reported cerebral abnormalities revealed by different imaging techniques. Although no unified COVID-19-specific pattern could be subtracted, a broad range of cerebral abnormalities were revealed by advanced neuroimaging (likely attributable to hypoxic, vascular, and inflammatory pathology), even in absence of structural clinical imaging findings. These abnormalities are validated by postmortem examinations. This scoping review emphasizes the added value of advanced neuroimaging compared to structural clinical imaging and highlights implications for brain functioning and long-term consequences in COVID-19.

Topographical Distribution of Neuroanatomical Abnormalities Following COVID-19 Invasion : A Systematic Literature Review

PURPOSE

This systematic review is aimed at synthesising the literature base to date on the frequency and topographical distribution of neuroanatomical changes seen on imaging following COVID-19 invasion with a focus on both the acute and chronic phases of the disease.

METHODS

In this study, 8 databases were systematically searched to identify relevant articles published from December 2019 to March 2022 and supplemented with a manual reference search. Data were extracted from the included studies and narrative synthesis was employed to integrate the findings.

RESULTS

A total of 110 studies met the inclusion criteria and comprised 119,307 participants (including 31,073 acute and 143 long COVID-19 patients manifesting neurological alterations) and controls. Considerable variability in both the localisation and nature of neuroanatomical abnormalities are noted along the continuum with a wide range of neuropathologies relating to the cerebrovascular/neurovascular system, (sub)cortical structures (including deep grey and white matter structures), brainstem, and predominant regional and/or global alterations in the cerebellum with varying degrees of spinal involvement.

CONCLUSION

Structural regional alterations on neuroimaging are frequently demonstrated in both the acute and chronic phases of SARS-CoV‑2 infection, particularly prevalent across subcortical, prefrontal/frontal and cortico-limbic brain areas as well as the cerebrovascular/neurovascular system. These findings contribute to our understanding of the acute and chronic effects of the virus on the nervous system and has the potential to provide information on acute and long-term treatment and neurorehabilitation decisions.

The interference between SARS-COV-2 and Alzheimer's disease: Potential immunological and neurobiological crosstalk from a kinase perspective reveals a delayed pandemic

Coronavirus disease 2019 (COVID-19) has infected over 700 million people, with up to 30% developing neurological manifestations, including dementias. However, there is a lack of understanding of common molecular brain markers causing Alzheimer's disease (AD). COVID-19 has etiological cofactors with AD, making patients with AD a vulnerable population at high risk of experiencing more severe symptoms and worse consequences. Both AD and COVID-19 have upregulated several shared kinases, leading to the repositioning of kinase inhibitors (KIs) for the treatment of both diseases. This review provides an overview of the interactions between the immune system and the nervous system in relation to receptor tyrosine kinases, including epidermal growth factor receptors, vascular growth factor receptors, and non-receptor tyrosine kinases such as Bruton tyrosine kinase, spleen tyrosine kinase, c-ABL, and JAK/STAT. We will discuss the promising results of kinase inhibitors in pre-clinical and clinical studies for both COVID-19 and Alzheimer's disease (AD), as well as the challenges in repositioning KIs for these diseases. Understanding the shared kinases between AD and COVID-19 could help in developing therapeutic approaches for both.

Plasma of COVID-19 Patients Does Not Alter Electrical Resistance of Human Endothelial Blood-Brain Barrier In Vitro

The pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 instigated the most serious global health crisis. Clinical presentation of COVID-19 frequently includes severe neurological and neuropsychiatric symptoms. However, it is presently unknown whether and to which extent pathological impairment of blood-brain barrier (BBB) contributes to the development of neuropathology during COVID-19 progression. In the present study, we used human induced pluripotent stem cells-derived brain endothelial cells (iBECs) to study the effects of blood plasma derived from COVID-19 patients on the BBB integrity in vitro. We also performed a comprehensive analysis of the cytokine and chemokine profiles in the plasma of COVID-19 patients, healthy and recovered individuals. We found significantly increased levels of interferon γ-induced protein 10 kDa, hepatocyte growth factor, and interleukin-18 in the plasma of COVID-19 patients. However, blood plasma from COVID-19 patients did not affect transendothelial electrical resistance in iBEC monolayers. Our results demonstrate that COVID-19-associated blood plasma inflammatory factors do not affect BBB paracellular pathway directly and suggest that pathological remodeling (if any) of BBB during COVID-19 may occur through indirect or yet unknown mechanisms.

Nervous system-related tropism of SARS-CoV-2 and autoimmunity in COVID-19 infection

The effects of SARS-CoV-2 in COVID-19 on the nervous system are incompletely understood. SARS-CoV-2 can infect endothelial cells, neurons, astrocytes, and oligodendrocytes with consequences for the host. There are indications that infection of these CNS-resident cells may result in long-term effects, including emergence of neurodegenerative diseases. Indirect effects of infection with SARS-CoV-2 relate to the induction of autoimmune disease involving molecular mimicry or/and bystander activation of T- and B cells and emergence of autoantibodies against various self-antigens. Data obtained in preclinical models of coronavirus-induced disease gives important clues for the understanding of nervous system-related assault of SARS-CoV-2. The pathophysiology of long-COVID syndrome and post-COVID syndrome in which autoimmunity and immune dysregulation might be the driving forces are still incompletely understood. A better understanding of nervous-system-related immunity in COVID-19 might support the development of therapeutic approaches. In this review, the current understanding of SARS-CoV-2 tropism for the nervous system, the associated immune responses, and diseases are summarized. The data indicates that there is viral tropism of SARS-CoV-2 in the nervous system resulting in various disease conditions. Prevention of SARS-CoV-2 infection by means of vaccination is currently the best strategy for the prevention of subsequent tissue damage involving the nervous system.

Brain MRI findings in severe COVID-19 patients: a meta-analysis

Introduction

Neurocognitive symptoms and dysfunction of various severities have become increasingly recognized as potential consequences of SARS-CoV-2 infection. Although there are numerous observational and subjective survey-reporting studies of neurological symptoms, by contrast, those studies describing imaging abnormalities are fewer in number.

Methods

This study conducted a metanalysis of 32 studies to determine the incidence of the common neurological abnormalities using magnetic resonance imaging (MRI) in patients with COVID-19.

Results

We also present the common clinical findings associated with MRI abnormalities. We report the incidence of any MRI abnormality to be 55% in COVID-19 patients with perfusion abnormalities (53%) and SWI abnormalities (44%) being the most commonly reported injuries. Cognitive impairment, ICU admission and/or mechanical ventilation status, older age, and hospitalization or longer length of hospital stay were the most common clinical findings associated with brain injury in COVID-19 patients.

Discussion

Overall, the presentation of brain injury in this study was diverse with no substantial pattern of injury emerging, yet most injuries appear to be of vascular origin. Moreover, analysis of the association between MRI abnormalities and clinical findings suggests that there are likely many mechanisms, both direct and indirect, by which brain injury occurs in COVID-19 patients.

COVID-19 hospitalization increases the risk of developing glioblastoma: a bidirectional Mendelian-randomization study

Background

As a result of the COVID-19 pandemic, patients with glioblastoma (GBM) are considered a highly vulnerable population. Despite this, the extent of the causative relationship between GBM and COVID-19 infection is uncertain.

Methods

Genetic instruments for SARS-CoV-2 infection (38,984 cases and 1,644,784 control individuals), COVID-19 hospitalization (8,316 cases and 1,549,095 control individuals), and COVID-19 severity (4,792 cases and 1,054,664 control individuals) were obtained from a genome-wide association study (GWAS) from European populations. A total of 6,183 GBM cases and 18,169 controls from GWAS were enrolled in our study. Their associations were evaluated by applying Mendelian randomization (MR) including IVW meta-analysis, MR-Egger regression, and weighted-median analysis. To make the conclusions more robust and reliable, sensitivity analyses were performed.

Results

Our results showed that genetically predicted COVID-19 hospitalization increases the risk of GBM (OR = 1.202, 95% CI = 1.035-1.395, p = 0.016). In addition, no increased risk of SARS-CoV-2 infection, COVID-19 hospitalization and severity were observed in patients with any type of genetically predicted GBM.

Conclusion

Our MR study indicated for the first time that genetically predicted COVID-19 hospitalization was demonstrated as a risk factor for the development of GBM.

Cerebral small vessel disease pathology in COVID-19 patients: A systematic review

Cerebral small vessel disease (CSVD) is the leading cause of vascular cognitive impairment and is associated with COVID-19. However, contributing factors that often accompany CSVD pathology in COVID-19 patients may influence the incidence of cerebrovascular complications. Thus, a mechanism linking COVID-19 and CSVD has yet to be uncovered and differentiated from age-related comorbidities (i.e., hypertension), and medical interventions during acute infection. We aimed to evaluate CSVD in acute and recovered COVID-19 patients and to differentiate COVID-19-related cerebrovascular pathology from the above-mentioned contributing factors by assessing the localization of microbleeds and ischemic lesions/infarctions in the cerebrum, cerebellum, and brainstem. A systematic search was performed in December 2022 on PubMed, Web of Science, and Embase using a pre-established search criterion related to history of, or active COVID-19 with CSVD pathology in adults. From a pool of 161 studies, 59 met eligibility criteria and were included. Microbleeds and ischemic lesions had a strong predilection for the corpus callosum and subcortical/deep white matter in COVID-19 patients, suggesting a distinct CSVD pathology. These findings have important implications for clinical practice and biomedical research as COVID-19 may independently, and through exacerbation of age-related mechanisms, contribute to increased incidence of CSVD.

Post-COVID-19 persistent olfactory, gustatory, and trigeminal chemosensory disorders: Definitions, mechanisms, and potential treatments

The nose and the oral cavities are the main sites for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) entry into the body. Smell and taste deficits are the most common acute viral manifestations. Persistent smell disorders are the most common and bothersome complications after SARS-CoV-2 infection, lasting for months to years. The mechanisms and treatment of persistent post-coronavirus disease 2019 (COVID-19) smell and taste disorders are still challenges. Information sources for the review are PubMed, Centers for Disease Control and Prevention, Ovid Medline, Embase, Scopus, Web of Science, International Prospective Register of Systematic Reviews, Cumulative Index to Nursing and Allied Health Literature, Elton Bryson Stephens Company, Cochrane Effective Practice and Organization of Care, Cooperation in Science and Technology, International Clinical Trials Registry Platform, World Health Organization, Randomized Controlled Trial Number Registry, and MediFind. This review summarizes the up-to-date information about the prevalence, patterns at onset, and prognoses of post-COVID-19 smell and taste disorders, evidence for the neurotropism of SARS-CoV-2 and the overlap between SARS-CoV-1, Middle East respiratory syndrome coronavirus, and SARS-CoV-2 in structure, molecular biology, mode of replication, and host pathogenicity, the suggested cellular and molecular mechanisms for these post-COVID19 chemosensory disorders, and the applied pharmacotherapies and interventions as trials to treat these disorders, and the recommendations for future research to improve understanding of predictors and mechanisms of these disorders. These are crucial for hopeful proper treatment strategies.

The Effects of Extrinsic and Intrinsic Factors on Neurogenesis

In the mammalian brain, neurogenesis is maintained throughout adulthood primarily in two typical niches, the subgranular zone (SGZ) of the dentate gyrus and the subventricular zone (SVZ) of the lateral ventricles and in other nonclassic neurogenic areas (e.g., the amygdala and striatum). During prenatal and early postnatal development, neural stem cells (NSCs) differentiate into neurons and migrate to appropriate areas such as the olfactory bulb where they integrate into existing neural networks; these phenomena constitute the multistep process of neurogenesis. Alterations in any of these processes impair neurogenesis and may even lead to brain dysfunction, including cognitive impairment and neurodegeneration. Here, we first summarize the main properties of mammalian neurogenic niches to describe the cellular and molecular mechanisms of neurogenesis. Accumulating evidence indicates that neurogenesis plays an integral role in neuronal plasticity in the brain and cognition in the postnatal period. Given that neurogenesis can be highly modulated by a number of extrinsic and intrinsic factors, we discuss the impact of extrinsic (e.g., alcohol) and intrinsic (e.g., hormones) modulators on neurogenesis. Additionally, we provide an overview of the contribution of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection to persistent neurological sequelae such as neurodegeneration, neurogenic defects and accelerated neuronal cell death. Together, our review provides a link between extrinsic/intrinsic factors and neurogenesis and explains the possible mechanisms of abnormal neurogenesis underlying neurological disorders.

The Two-Way Route between Delirium Disorder and Dementia: Insights from COVID-19

BACKGROUND

Delirium disorder is a frequent neurological complication of SARS-CoV-2 infection and associated with increased disease severity and mortality. Cognitive impairment is a major risk factor for developing delirium disorder during COVID-19, which, in turn, increases the risk of subsequent neurological complications and cognitive decline.

SUMMARY

The bidirectional connection between delirium disorder and dementia likely resides at multiple levels, and its pathophysiological mechanisms during COVID-19 include endothelial damage, blood-brain barrier dysfunction, and local inflammation, with activation of microglia and astrocytes. Here, we describe the putative pathogenic pathways underlying delirium disorder during COVID-19 and highlight how they cross with the ones leading to neurodegenerative dementia.

KEY MESSAGES

The analysis of the two-sided link can offer useful insights for confronting with long-term neurological consequences of COVID-19 and framing future prevention and early treatment strategies.

Astrocytes and the Psychiatric Sequelae of COVID-19: What We Learned from the Pandemic

COVID-19, initially regarded as specific lung disease, exhibits an extremely broad spectrum of symptoms. Extrapulmonary manifestations of the disease also include important neuropsychiatric symptoms with atypical characteristics. Are these disturbances linked to stress accompanying every systemic infection, or are due to specific neurobiological changes associated with COVID-19? Evidence accumulated so far indicates that the pathophysiology of COVID-19 is characterized by systemic inflammation, hypoxia resulting from respiratory failure, and neuroinflammation (either due to viral neurotropism or in response to cytokine storm), all affecting the brain. It is reasonable to hypothesize that all these events may initiate or worsen psychiatric and cognitive disorders. Damage to the brain triggers a specific type of reactive response mounted by neuroglia cells, in particular by astrocytes which are the homeostatic cell par excellence. Astrocytes undergo complex morphological, biochemical, and functional remodeling aimed at mobilizing the regenerative potential of the central nervous system. If the brain is not directly damaged, resolution of systemic pathology usually results in restoration of the physiological homeostatic status of neuroglial cells. The completeness and dynamics of this process in pathological conditions remain largely unknown. In a subset of patients, glial cells could fail to recover after infection thus promoting the onset and progression of COVID-19-related neuropsychiatric diseases. There is evidence from post-mortem examinations of the brains of COVID-19 patients of alterations in both astrocytes and microglia. In conclusion, COVID-19 activates a huge reactive response of glial cells, that physiologically act as the main controller of the inflammatory, protective and regenerative events. However, in some patients the restoration of glial physiological state does not occur, thus compromising glial function and ultimately resulting in homeostatic failure underlying a set of specific neuropsychiatric symptoms related to COVID-19.

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.

Coronavirus Disease: Subacute to Chronic Neuroimaging Findings

Several neurologic disorders are associated with coronavirus disease 2019 (COVID-19). In this article, clinical syndromes typically occurring in the subacute to chronic phase of illness and their neuroimaging findings are described with discussion of their COVID-19 specific features and prognosis. Proposed pathogenic mechanisms of these neuroimaging findings and challenges in determining etiology are reviewed.

Mechanisms, Effects, and Management of Neurological Complications of Post-Acute Sequelae of COVID-19 (NC-PASC)

With a growing number of patients entering the recovery phase following infection with SARS-CoV-2, understanding the long-term neurological consequences of the disease is important to their care. The neurological complications of post-acute sequelae of SARS-CoV-2 infection (NC-PASC) represent a myriad of symptoms including headaches, brain fog, numbness/tingling, and other neurological symptoms that many people report long after their acute infection has resolved. Emerging reports are being published concerning COVID-19 and its chronic effects, yet limited knowledge of disease mechanisms has challenged therapeutic efforts. To address these issues, we review broadly the literature spanning 2020-2022 concerning the proposed mechanisms underlying NC-PASC, outline the long-term neurological sequelae associated with COVID-19, and discuss potential clinical interventions.

Effects of COVID-19 on Synaptic and Neuronal Degeneration

Neurons are the basic building blocks of the human body's neurological system. Atrophy is defined by the disintegration of the connections between cells that enable them to communicate. Peripheral neuropathy and demyelinating disorders, as well as cerebrovascular illnesses and central nervous system (CNS) inflammatory diseases, have all been linked to brain damage, including Parkinson's disease (PD). It turns out that these diseases have a direct impact on brain atrophy. However, it may take some time after the onset of one of these diseases for this atrophy to be clearly diagnosed. With the emergence of the Coronavirus disease 2019 (COVID-19) pandemic, there were several clinical observations of COVID-19 patients. Among those observations is that the virus can cause any of the diseases that can lead to brain atrophy. Here we shed light on the research that tracked the relationship of these diseases to the COVID-19 virus. The importance of this review is that it is the first to link the relationship between the Coronavirus and diseases that cause brain atrophy. It also indicates the indirect role of the virus in dystrophy.

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.

Posterior reversible encephalopathy syndrome in critical COVID-19 patients: Report of 2 cases

Posterior reversible encephalopathy syndrome is an acute neurological disorder characterized by variable symptoms and radiological images characteristic of vasogenic parietal-occipital edema. It is associated with clinical conditions such as high blood pressure, infection/sepsis, or cytotoxic/immunosuppressive drugs, among others. It is characterized pathophysiologically by endothelial damage with breakdown of blood-brain barrier, cerebral hypoperfusion, and vasogenic edema. The cases are presented on 2 critical COVID-19 patients who were admitted to pneumonia requiring mechanical ventilation and who, after removing sedation, developed acute and reversible neurological symptoms consisting of epilepsy and encephalopathy, associated with hyperintense subcortical lesions on brain magnetic resonance imaging compatible with posterior reversible encephalopathy syndrome. SARS-CoV-2 coronavirus would activate an inflammatory response that would damage brain endothelium. It could be triggered by cytokine release, as well as by direct viral injury, given that endothelium expresses ACE2 receptors. It could explain the possible association between posterior reversible encephalopathy syndrome and COVID-19.

Post-mortem Imaging of Brain/Spine Injuries: The Importance of a Comprehensive Forensic Approach

In forensic investigations, the limitations of the traditional purely autoptic approach can be overcome through post-mortem imaging (virtopsy). Virtospy has several applications to the investigation of brain and spinal injuries, whose analysis can be of forensic interest, especially in cases of suspected malpractice. In this scoping review, we briefly describe the main applications of the two most common post-mortem radiological techniques (computed tomography (CT) and magnetic resonance imaging (MRI)) to the forensic investigation of brain and spinal injuries in cases of medical malpractice or traumatic (accidental/homicidal/suicidal) deaths. Although CT represents the traditional approach to post-mortem imaging, MRI is proving to be a valuable tool to investigate brain and spinal injuries and lesions. These post-mortem radiological techniques can also be used to guide the surgeons in simulated surgical procedures on corpses in the context of training programs, thus helping operators to improve technical and non-technical skills and to reduce the risk of avoidable errors.

Cognitive after-effects and associated correlates among post-illness COVID-19 survivors: a cross-sectional study, Egypt

Background

COVID-19’s after-effects among survivors are of increased concern. The cognitive aftermath of COVID-19 virus infection was underrated. This study aimed to identify and compare the cognitive impairment (CI) and its correlates among COVID-19 survivors and control subjects. A total of 85 adults who survived COVID-19 virus infection and an equal number of control subjects (matched for age, sex, education, and socioeconomic level) were included in this study. They were recruited from Zagazig University Hospitals, Sharkia Province, Egypt. All subjects were interviewed utilizing a semistructured demographic and clinical checklist, the Montreal Cognitive Assessment (MoCA) test, and the Hospital Anxiety Depression Scale (HADS).

Results

More than half of COVID-19 survivors experienced CI (compared to only 8% of control subjects). Individuals who survived COVID-19 virus infection were more likely to have impairments in visuo-executive functions (OR: 0.3, 95% CI 0.2–0.5), attention (OR: 0.4, 95% CI 0.3–0.7), language (OR: 0.2, 95% CI 0.1–0.5), delayed recall (OR: 0.5, 95% CI 0.4–0.6), and total MoCA Scores (OR: 0.1, 95% CI 0.04–0.2). Among COVID-19 survivors, those who experienced CI were likely to be older (OR: 1.1, 95% CI 1.03–1.2), and of low-to-moderate education (OR: 4.9, 95% CI 1.6–15.1).

Conclusions

CI was prevalent among COVID-19 survivors. The visuo-executive functions, attention, language, and delayed recall were the most affected domains. Older age and lower educational level predicted CI in COVID-19 survivors.

Neurological Complications of SARS-CoV-2 Infection and COVID-19 Vaccines: From Molecular Mechanisms to Clinical Manifestations

Coronavirus Disease 2019 (COVID-19) is an infectious disease, caused by the Severe Acute Respiratory Syndrome Coronavirus-2 (SARS-CoV-2), that reached pandemic proportions in 2020. Despite the fact that it was initially characterized by pneumonia and acute respiratory distress syndrome, it is now clear that the nervous system is also compromised in one third of these patients. Indeed, a significant proportion of COVID-19 patients suffer nervous system damage via a plethora of mechanisms including hypoxia, coagulopathy, immune response to the virus, and the direct effect of SARS-CoV-2 on endothelial cells, neurons, astrocytes, pericytes and microglia. Additionally, a low number of previously healthy individuals develop a variety of neurological complications after receiving COVID-19 vaccines and a large proportion of COVID-19 survivors experience longlasting neuropsychiatric symptoms. In conclusion, COVID-19 is also a neurological disease, and the direct and indirect effects of the virus on the nervous system have a significant impact on the morbidity and mortality of these patients. Here we will use the concept of the neurovascular unit, assembled by endothelial cells, basement membrane, perivascular astrocytes, neurons and microglia, to review the effects of SARS-CoV-2 in the nervous system. We will then use this information to review data published to this date on the neurological manifestations of COVID-19, the post- COVID syndrome and COVID-19 vaccines.

Brain fog as a Long-term Sequela of COVID-19

Increasing data indicate that people infected with COVID-19 are at high risk for developing long-term neurological complications, such as "brain fog" or cognitive impairment. However, little is known about the long-term outcomes of COVID-19 survivors. This also applies to the prevalence, risk factors, and pathobiological findings associated with these consequences. Although cognitive complications are anticipated in patients who require a long-lasting hospital stay or intubation, milder cases of COVID-19 with no record of hospitalization have also been shown to experience assessable cognitive challenges. Cognitive impairment can have a devastating impact on daily functioning. Understanding the long-term effect of COVID-19 on cognitive function is vital for applying specific schemes to those who wish to return to their jobs productively.

Post-Acute Sequelae of SARS-CoV-2 Infection: A Descriptive Clinical Study

OBJECTIVE

The investigators aimed to describe the clinical experience of a single center reporting on neuropsychiatric findings among patients experiencing persistent symptoms as part of post-acute sequelae of SARS-CoV-2 (PASC) infection.

METHODS

Data were collected retrospectively (between February 2020 and May 2021) from a cohort (N=100) within a COVID-19 survivors study of patients with persistent symptoms enrolled after a short inpatient stay or who had been outpatients never hospitalized. Patients without confirmatory positive PCR or antibody diagnostic test results were grouped separately as presumptive cases (N=13).

RESULTS

Of the 87 patients with confirmed SARS-CoV-2, 63 (72.4%) were female, and 65 (74.7%) were White. The mean age was 49.2 years (SD=14.9). The most prevalent symptoms after COVID-19 infection were fatigue, "brain fog," headache, anxiety, and sleep issues. Attention and executive function were frequently impaired. The mean Montreal Cognitive Assessment score was 26.0 (SD=2.8). Concentration and attention as well as memory issues were both significantly correlated with the complaint of brain fog.

CONCLUSIONS

These preliminary findings suggest that post-acute sequelae of SARS-CoV-2 vary in frequency and duration with relation to premorbid history and that these conditions affect functional domains and patients' ability to return to work. Longitudinal research with larger cohorts is needed to characterize PASC and to optimize care, especially for vulnerable populations.

Autoimmunity and SARS-CoV-2 infection: Unraveling the link in neurological disorders

According to the World Health Organization, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has already infected more than 400 million people and caused over 5 million deaths globally. The infection is associated with a wide spectrum of clinical manifestations, ranging from no signs of illness to severe pathological complications that go beyond the typical respiratory symptoms. On this note, new-onset neurological and neuropsychiatric syndromes have been increasingly reported in a large fraction of COVID-19 patients, thus potentially representing a significant public health threat. Although the underlying pathophysiological mechanisms remain elusive, a growing body of evidence suggests that SARS-CoV-2 infection may trigger an autoimmune response, which could potentially contribute to the establishment and/or exacerbation of neurological disorders in COVID-19 patients. Shedding light on this aspect is urgently needed for the development of effective therapeutic intervention. This review highlights the current knowledge of the immune responses occurring in Neuro-COVID patients and discusses potential immune-mediated mechanisms by which SARS-CoV-2 infection may trigger neurological complications.

Sequelae of COVID-19 among previously hospitalized patients up to 1 year after discharge: a systematic review and meta-analysis

OBJECTIVE

Although complications and clinical symptoms of COVID-19 have been elucidated, the prevalence of long-term sequelae of COVID-19 is less clear in previously hospitalized COVID-19 patients. This review and meta-analysis present the occurrence of different symptoms up to 1 year of follow-up for previously hospitalized patients.

METHODS

We performed a systematic review from PubMed and Web of Science using keywords such as "COVID-19", "SARS-CoV-2", "sequelae", "long-term effect" and included studies with at least 3-month of follow-up. Meta-analyses using random-effects models were performed to estimate the pooled prevalence for different sequelae. Subgroup analyses were conducted by different follow-up time, regions, age and ICU admission.

RESULTS

72 articles were included in the meta-analyses after screening 11,620 articles, identifying a total of 167 sequelae related to COVID-19 from 88,769 patients. Commonly reported sequelae included fatigue (27.5%, 95% CI 22.4-33.3%, range 1.5-84.9%), somnipathy (20.1%, 95% CI 14.7-26.9%, range 1.2-64.8%), anxiety (18.0%, 95% CI 13.8-23.1%, range 0.6-47.8%), dyspnea (15.5%, 95% CI 11.3-20.9%, range 0.8-58.4%), PTSD (14.6%, 95% CI 11.3-18.7%, range 1.2-32.0%), hypomnesia (13.4%, 95% CI 8.4-20.7%, range 0.6-53.8%), arthralgia (12.9%, 95% CI 8.4-19.2%, range 0.0-47.8%), depression (12.7%, 95% CI 9.3-17.2%, range 0.6-37.5%), alopecia (11.2%, 95% CI 6.9-17.6%, range 0.0-47.0%) over 3-13.2 months of follow-up. The prevalence of most symptoms reduced after > 9 months of follow-up, but fatigue and somnipathy persisted in 26.2% and 15.1%, respectively, of the patients over a year. COVID-19 patients from Asia reported a lower prevalence than those from other regions.

CONCLUSIONS

This review identified a wide spectrum of COVID-19 sequelae in previously hospitalized COVID-19 patients, with some symptoms persisting up to 1 year. Management and rehabilitation strategies targeting these symptoms may improve quality of life of recovered patients.

Gut Microbiota Dynamics in Relation to Long-COVID-19 Syndrome: Role of Probiotics to Combat Psychiatric Complications

Increasing numbers of patients who recover from COVID-19 report lasting symptoms, such as fatigue, muscle weakness, dementia, and insomnia, known collectively as post-acute COVID syndrome or long COVID. These lasting symptoms have been examined in different studies and found to influence multiple organs, sometimes resulting in life-threating conditions. In this review, these symptoms are discussed in connection to the COVID-19 and long-COVID-19 immune changes, highlighting oral and psychiatric health, as this work focuses on the gut microbiota’s link to long-COVID-19 manifestations in the liver, heart, kidney, brain, and spleen. A model of this is presented to show the biological and clinical implications of gut microbiota in SARS-CoV-2 infection and how they could possibly affect the therapeutic aspects of the disease. Probiotics can support the body’s systems in fighting viral infections. This review focuses on current knowledge about the use of probiotics as adjuvant therapies for COVID-19 patients that might help to prevent long-COVID-19 complications.

Exacerbation of Pre-existing Neurological Symptoms With COVID-19 in Patients With Chronic Neurological Diseases: An Updated Systematic Review

The neurotropism of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can potentially explain the worsening of symptoms in patients with a history of neurological conditions such as stroke, Parkinson's disease, Alzheimer's, and epilepsy. Several studies have reported that these pre-existing conditions may worsen with a higher frequency of flare-ups, thus resulting in a more significant risk of patient mortality. In this review, we sought to provide an overview of the relationship between pre-existing neurological disorders and COVID-19, focusing on whether the initial infection directly influenced the severity of symptoms. We systematically searched the electronic database PubMed (MEDLINE) and used specific keywords related to our aims from January 2020 to July 2022. All articles published on COVID-19 with keywords pertaining to pre-existing neurological diseases were retrieved and subsequently analyzed. After independent review, the data from 107 articles were selected and evaluated. After analyzing the data from selected articles reviewing the effect of COVID-19 on neurological conditions, we have documented the relationship between said pre-existing neurological diseases, showing an increased risk of hospitalization, admission length, worsening of symptoms, and even mortality in COVID-19 patients.

Widespread white matter oedema in subacute COVID-19 patients with neurological symptoms

While neuropathological examinations in patients who died from COVID-19 revealed inflammatory changes in cerebral white matter, cerebral MRI frequently fails to detect abnormalities even in the presence of neurological symptoms. Application of multi-compartment diffusion microstructure imaging (DMI), that detects even small volume shifts between the compartments (intra-axonal, extra-axonal and free water/CSF) of a white matter model, is a promising approach to overcome this discrepancy. In this monocentric prospective study, a cohort of 20 COVID-19 inpatients (57.3 ± 17.1 years) with neurological symptoms (e.g. delirium, cranial nerve palsies) and cognitive impairments measured by the Montreal Cognitive Assessment (MoCA test; 22.4 ± 4.9; 70% below the cut-off value <26/30 points) underwent DMI in the subacute stage of the disease (29.3 ± 14.8 days after positive PCR). A comparison of whole-brain white matter DMI parameters with a matched healthy control group (n = 35) revealed a volume shift from the intra- and extra-axonal space into the free water fraction (V-CSF). This widespread COVID-related V-CSF increase affected the entire supratentorial white matter with maxima in frontal and parietal regions. Streamline-wise comparisons between COVID-19 patients and controls further revealed a network of most affected white matter fibres connecting widespread cortical regions in all cerebral lobes. The magnitude of these white matter changes (V-CSF) was associated with cognitive impairment measured by the MoCA test (r = -0.64, P = 0.006) but not with olfactory performance (r = 0.29, P = 0.12). Furthermore, a non-significant trend for an association between V-CSF and interleukin-6 emerged (r = 0.48, P = 0.068), a prominent marker of the COVID-19 related inflammatory response. In 14/20 patients who also received cerebral 18F-FDG PET, V-CSF increase was associated with the expression of the previously defined COVID-19-related metabolic spatial covariance pattern (r = 0.57; P = 0.039). In addition, the frontoparietal-dominant pattern of neocortical glucose hypometabolism matched well to the frontal and parietal focus of V-CSF increase. In summary, DMI in subacute COVID-19 patients revealed widespread volume shifts compatible with vasogenic oedema, affecting various supratentorial white matter tracts. These changes were associated with cognitive impairment and COVID-19 related changes in 18F-FDG PET imaging.

The COVID-19 pandemic and Alzheimer's disease: mutual risks and mechanisms

Coronavirus disease 2019 (COVID-19), which is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a life-threatening disease, especially in elderly individuals and those with comorbidities. The predominant clinical manifestation of COVID-19 is respiratory dysfunction, while neurological presentations are increasingly being recognized. SARS-CoV-2 invades host cells primarily via attachment of the spike protein to the angiotensin-converting enzyme 2 (ACE2) receptor expressed on cell membranes. Patients with Alzheimer's disease (AD) are more susceptible to SARS-CoV-2 infection and prone to severe clinical outcomes. Recent studies have revealed some common risk factors for AD and COVID-19. An understanding of the association between COVID-19 and AD and the potential related mechanisms may lead to the development of novel approaches to treating both diseases. In the present review, we first summarize the mechanisms by which SARS-CoV-2 invades the central nervous system (CNS) and then discuss the associations and potential shared key factors between COVID-19 and AD, with a focus on the ACE2 receptor, apolipoprotein E (APOE) genotype, age, and neuroinflammation.

SARS-CoV-2 Brain Regional Detection, Histopathology, Gene Expression, and Immunomodulatory Changes in Decedents with COVID-19

Brains of 42 COVID-19 decedents and 107 non-COVID-19 controls were studied. RT-PCR screening of 16 regions from 20 COVID-19 autopsies found SARS-CoV-2 E gene viral sequences in 7 regions (2.5% of 320 samples), concentrated in 4/20 subjects (20%). Additional screening of olfactory bulb (OB), amygdala (AMY) and entorhinal area for E, N1, N2, RNA-dependent RNA polymerase, and S gene sequences detected one or more of these in OB in 8/21 subjects (38%). It is uncertain whether these RNA sequences represent viable virus. Significant histopathology was limited to 2/42 cases (4.8%), one with a large acute cerebral infarct and one with hemorrhagic encephalitis. Case-control RNAseq in OB and AMY found more than 5000 and 700 differentially expressed genes, respectively, unrelated to RT-PCR results; these involved immune response, neuronal constituents, and olfactory/taste receptor genes. Olfactory marker protein-1 reduction indicated COVID-19-related loss of OB olfactory mucosa afferents. Iba-1-immunoreactive microglia had reduced area fractions in cerebellar cortex and AMY, and cytokine arrays showed generalized downregulation in AMY and upregulation in blood serum in COVID-19 cases. Although OB is a major brain portal for SARS-CoV-2, COVID-19 brain changes are more likely due to blood-borne immune mediators and trans-synaptic gene expression changes arising from OB deafferentation.

Putative role of mitochondria in SARS-CoV-2 mediated brain dysfunctions: a prospect

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of the COVID-19 pandemic. Though the virus primarily damages the respiratory and cardiovascular systems after binding to the host angiotensin-converting enzyme 2 (ACE2) receptors, it has the potential to affect all major organ systems, including the human nervous system. There are multiple clinical reports of anosmia, dizziness, headache, nausea, ageusia, encephalitis, demyelination, neuropathy, memory loss, and neurological complications in SARS-CoV-2 infected individuals. Though the molecular mechanism of these brain dysfunctions during SARS-CoV-2 infection is elusive, the mitochondria seem to be an integral part of this pathogenesis. Emerging research findings suggest that the dysfunctional mitochondria and associated altered bioenergetics in the infected host cells lead to altered energy metabolism in the brain of Covid-19 patients. The interactome between viral proteins and mitochondrial proteins during Covid-19 pathogenesis also provides evidence for the involvement of mitochondria in SARS-CoV-2-induced brain dysfunctions. The present review discusses the possible role of mitochondria in disturbing the SARS-CoV-2 mediated brain functions, with the potential to use this information to prevent and treat these impairments.

SARS-CoV-2 consequences for mental health: Neuroinflammatory pathways linking COVID-19 to anxiety and depression

The coronavirus disease 2019 (COVID-19) pandemic has been linked to an increased prevalence of mental health disorders, particularly anxiety and depression. Moreover, the COVID-19 pandemic has caused stress in people worldwide due to several factors, including fear of infection; social isolation; difficulty in adapting to new routines; lack of coping methods; high exposure to social media, misinformation, and fake reports; economic impact of the measures implemented to slow the contagion and concerns regarding the disease pathogenesis. COVID-19 patients have elevated levels of pro-inflammatory cytokines, such as interleukin (IL)-1β, IL-6, and tumor necrosis factor-α, and other inflammation-related factors. Furthermore, invasion of the central nervous system by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may potentially contribute to neuroinflammatory alterations in infected individuals. Neuroinflammation, a consequence of psychological stress due to the COVID-19 pandemic, may also play a role in the development of anxiety and depressive symptoms in the general population. Considering that neuroinflammation plays a significant role in the pathophysiology of depression and anxiety, this study investigated the effects of SARS-CoV-2 on mental health and focused on the impact of the COVID-19 pandemic on the neuroinflammatory pathways.

Cognitive Assessment in SARS-CoV-2 Patients: A Systematic Review

Background

Patients with post-infective severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) often show both short- and long-term cognitive deficits within the dysexecutive/inattentive spectrum. However, little is known about which cognitive alterations are commonly found in patients recovered from SARS-CoV-2, and which psychometric tools clinicians should consider when assessing cognition in this population. The present work reviewed published studies to provide a critical narrative of neuropsychological (NPs) deficits commonly observed after SARS-CoV-2 infection and the tests most suited for detecting such cognitive sequelae depending on illness severity.

Methods

This review followed the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines and was pre-registered on Prospective Register of Systematic Reviews (PROSPERO) (CRD42021253079). Observational studies quantitatively assessing cognition in patients with post-infective SARS-CoV-2 were considered. From 711 retrieved articles, 19 studies conducted on patients with SARS-CoV-2 without medical comorbidities were included and stratified by disease severity.

Results

The majority of studies (N = 13) adopted first-level tests. The most frequently administered screeners were the Montreal Cognitive Assessment (MoCA) and the Mini-Mental State Examination (MMSE)—with the former more likely to detect mild, and the latter moderate/severe deficits. Among second-level tests, those assessing attention and executive functions (EFs) were highly represented. Remotely-delivered tests yielded lower percentages of cognitive impairment. Overall, cognitive domains often found to be impaired were EFs, attention, and memory.

Conclusion

Cognitive sequelae in patients with post-infective SARS-CoV-2 can be detected with NPs testing. Depending on the psychometric test features, the likelihood of observing cognitive deficits can vary. Further studies on larger sample sizes are needed to investigate the clinical usefulness of second-level tools. The primary goal of preventative health services should be the early detection and intervention of emerging cognitive deficits.

Neurological sequela and disruption of neuron-glia homeostasis in SARS-CoV-2 infection

The coronavirus disease 2019 (COVID-19) pandemic is responsible for 267 million infections and over 5 million deaths globally. COVID-19 is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), a single-stranded RNA beta-coronavirus, which causes a systemic inflammatory response, multi-organ damage, and respiratory failure requiring intubation in serious cases. SARS-CoV-2 can also trigger neurological conditions and syndromes, which can be long-lasting and potentially irreversible. Since COVID-19 infections continue to mount, the burden of SARS-CoV-2-induced neurologic sequalae will rise in parallel. Therefore, understanding the spectrum of neurological clinical presentations in SARS-CoV-2 is needed to manage COVID-19 patients, facilitate diagnosis, and expedite earlier treatment to improve outcomes. Furthermore, a deeper knowledge of the neurological SARS-CoV-2 pathomechanisms could uncover potential therapeutic targets to prevent or mitigate neurologic damage secondary to COVID-19 infection. Evidence indicates a multifaceted pathology involving viral neurotropism and direct neuroinvasion along with cytokine storm and neuroinflammation leading to nerve injury. Importantly, pathological processes in neural tissue are non-cell autonomous and occur through a concerted breakdown in neuron-glia homeostasis, spanning neuron axonal damage, astrogliosis, microgliosis, and impaired neuron-glia communication. A clearer mechanistic and molecular picture of neurological pathology in SARS-CoV-2 may lead to effective therapies that prevent or mitigate neural damage in patients contracting and developing severe COVID-19 infection.

Neuropathological Aspects of SARS-CoV-2 Infection: Significance for Both Alzheimer's and Parkinson's Disease

Evidence suggests that SARS-CoV-2 entry into the central nervous system can result in neurological and/or neurodegenerative diseases. In this review, routes of SARS-Cov-2 entry into the brain via neuroinvasive pathways such as transcribrial, ocular surface or hematogenous system are discussed. It is argued that SARS-Cov-2-induced cytokine storm, neuroinflammation and oxidative stress increase the risk of developing neurodegenerative diseases such as Alzheimer's disease and Parkinson's disease. Further studies on the effects of SARS-CoV-2 and its variants on protein aggregation, glia or microglia activation, and blood-brain barrier are warranted.

Impact of COVID-19 on the Onset and Progression of Alzheimer's Disease and Related Dementias: A Roadmap for Future Research

COVID-19 causes lasting neurological symptoms in some survivors. Like other infections, COVID-19 may increase risk of cognitive impairment. This perspective highlights four knowledge gaps about COVID-19 that need to be filled to avoid this possible health issue. The first is the need to identify the COVID-19 symptoms, genetic polymorphisms and treatment decisions associated with risk of cognitive impairment. The second is the absence of model systems in which to test hypotheses relating infection to cognition. The third is the need for consortia for studying both existing and new longitudinal cohorts in which to monitor long term consequences of COVID-19 infection. A final knowledge gap discussed is the impact of the isolation and lack of social services brought about by quarantine/lockdowns on people living with dementia and their caregivers. Research into these areas may lead to interventions that reduce the overall risk of cognitive decline for COVID-19 survivors.

Parkinson’s Disease and SARS-CoV-2 Infection: Particularities of Molecular and Cellular Mechanisms Regarding Pathogenesis and Treatment

Accumulating data suggest that chronic neuroinflammation-mediated neurodegeneration is a significant contributing factor for progressive neuronal and glial cell death in age-related neurodegenerative pathology. Furthermore, it could be encountered as long-term consequences in some viral infections, including post-COVID-19 Parkinsonism-related chronic sequelae. The current systematic review is focused on a recent question aroused during the pandemic’s successive waves: are there post-SARS-CoV-2 immune-mediated reactions responsible for promoting neurodegeneration? Does the host’s dysregulated immune counter-offensive contribute to the pathogenesis of neurodegenerative diseases, emerging as Parkinson’s disease, in a complex interrelation between genetic and epigenetic risk factors? A synthetic and systematic literature review was accomplished based on the ”Preferred Reporting Items for Systematic Principles Reviews and Meta-Analyses” (PRISMA) methodology, including registration on the specific online platform: International prospective register of systematic reviews—PROSPERO, no. 312183. Initially, 1894 articles were detected. After fulfilling the five steps of the selection methodology, 104 papers were selected for this synthetic review. Documentation was enhanced with a supplementary 47 bibliographic resources identified in the literature within a non-standardized search connected to the subject. As a final step of the PRISMA method, we have fulfilled a Population-Intervention-Comparison-Outcome-Time (PICOT)/Population-Intervention-Comparison-Outcome-Study type (PICOS)—based metanalysis of clinical trials identified as connected to our search, targeting the outcomes of rehabilitative kinesitherapeutic interventions compared to clinical approaches lacking such kind of treatment. Accordingly, we identified 10 clinical trials related to our article. The multi/interdisciplinary conventional therapy of Parkinson’s disease and non-conventional multitarget approach to an integrative treatment was briefly analyzed. This article synthesizes the current findings on the pathogenic interference between the dysregulated complex mechanisms involved in aging, neuroinflammation, and neurodegeneration, focusing on Parkinson’s disease and the acute and chronic repercussions of COVID-19. Time will tell whether COVID-19 neuroinflammatory events could trigger long-term neurodegenerative effects and contribute to the worsening and/or explosion of new cases of PD. The extent of the interrelated neuropathogenic phenomenon remains obscure, so further clinical observations and prospective longitudinal cohort studies are needed.

Post-COVID-19 memory complaints: Prevalence and associated factors

INTRODUCTION

Memory complaints resulting from COVID-19 may have a significant impact on the survivors' quality of life. Unfortunately, there is insufficient information available on memory loss and its relationship to COVID-19. Therefore, the purpose of this research was to determine the prevalence of memory complaints in post-COVID-19 patients and to find potential contributing factors.

METHOD

A cross-sectional survey was conducted on 401 individuals who had previously been diagnosed with COVID-19 at four COVID testing centers situated across Bangladesh. The MAC-Q questionnaire was used to evaluate memory. A binary logistic regression model was fit to study the variables related to memory complaints, with a p-value of <0.05 deemed statistically significant.

RESULT

Memory complaints was prevalent in 19.2% of the post-COVID patients. Individual predictor analysis revealed that among the treatment modalities, steroids and antibiotics were associated with impaired memory. Multiple logistic regression showed that individuals who recovered from COVID-19 within six to twelve months were more likely to have memory deficits. Even though age, sex, oxygen demand, and hospitalization were not linked with memory complaints, rural residents exhibited more significant memory complaints than urban residents.

CONCLUSION

Nearly one-fifth of the COVID-19 patients suffer from various degrees of memory complaints within one year. However, no association was found between COVID-19 severity to memory complaints.

COVID-19: Cellular and Molecular Mechanisms of Brain Damage

The most common clinical manifestation of COVID-19 is bilateral pneumonia, a diffuse, alveolar injury with severe microangiopathy. Systemic infection is accompanied by an increase in circulating chemokines and interleukins in the blood, which penetrate the blood–brain barrier (BBB) and enter the brain. Clinical materials indicate lesions of the brain and peripheral nervous system, as well as neurodegenerative and mental disorders. Due to violations of the cerebral endothelium system and changes in the balance of ACE2-coupled cytochemical processes, coagulopathy develops, leading to microthrombosis and vascular occlusion. The concept of SARS-CoV-2 “neurotropism” is discussed as a rationale for the penetration by the virus into the brain. Infection can occur as axonal transport through the bulbar zone and the olfactory area of the cerebral cortex. Even more common is the “hematogenous pathway” of viral transfection, which includes damage to the vascular endothelium and a violation of the protective role of the BBB. Another concept that explains the mechanism of brain damage relates to the phenomenon of neuroinflammation. Astrocytes and microglia are considered potential targets of the SARS-CoV-2 coronavirus. The dissonance of the biochemical processes of the axis ACE2/ACE and changes in the functions of angiotensin peptides leads to the activation of astroglia with the development of neurodestructive processes in COVID-19.

Incidence of white matter lesions in hospitalized COVID-19 patients: A meta-analysis

OBJECTIVE

Novel coronavirus disease 2019 (COVID-19) has been found to be associated with encephalopathy and brain imaging abnormalities. The identification of incident white matter lesions, known to be associated with cerebral microcirculatory failure and cerebrovascular disease, in COVID-19 patients is of clinical and scientific interest. We performed a meta-analysis to investigate the incidence of white matter lesions (WMLs) in hospitalized COVID-19 patients.

METHODS

PubMed, EMBASE, and the Cochrane Library were searched for studies on brain imaging abnormalities in hospitalized COVID-19 patients. The terms used included "white matter lesions," "white matter hyperintensity," "COVID-19," "coronavirus," and "SARS-CoV-2." A random-effects meta-analysis was conducted to obtain a pooled estimate of WML prevalence in hospitalized COVID-19 patients.

RESULTS

A total of 4 eligible studies involving 362 patients (144 with WMLs and 218 without) were included in the meta-analysis. We found the pooled estimate of WML prevalence to be 20% (ES 0.20; 95% CI 0.00-0.54; p = .03).

CONCLUSIONS

The estimated pooled prevalence rate of WMLs was approximately 20% in hospitalized COVID-19 patients, albeit lower than the crude prevalence rate (39.8%).