Research Accessibility Team (RAT). The microvascular hypothesis underlying neurologic manifestations of long COVID-19 and possible therapeutic strategies

Cerebromicrovascular mechanisms contributing to long COVID: implications for neurocognitive health

Long COVID (also known as post-acute sequelae of SARS-CoV-2 infection [PASC] or post-COVID syndrome) is characterized by persistent symptoms that extend beyond the acute phase of SARS-CoV-2 infection, affecting approximately 10% to over 30% of those infected. It presents a significant clinical challenge, notably due to pronounced neurocognitive symptoms such as brain fog. The mechanisms underlying these effects are multifactorial, with mounting evidence pointing to a central role of cerebromicrovascular dysfunction. This review investigates key pathophysiological mechanisms contributing to cerebrovascular dysfunction in long COVID and their impacts on brain health. We discuss how endothelial tropism of SARS-CoV-2 and direct vascular infection trigger endothelial dysfunction, impaired neurovascular coupling, and blood-brain barrier disruption, resulting in compromised cerebral perfusion. Furthermore, the infection appears to induce mitochondrial dysfunction, enhancing oxidative stress and inflammation within cerebral endothelial cells. Autoantibody formation following infection also potentially exacerbates neurovascular injury, contributing to chronic vascular inflammation and ongoing blood-brain barrier compromise. These factors collectively contribute to the emergence of white matter hyperintensities, promote amyloid pathology, and may accelerate neurodegenerative processes, including Alzheimer's disease. This review also emphasizes the critical role of advanced imaging techniques in assessing cerebromicrovascular health and the need for targeted interventions to address these cerebrovascular complications. A deeper understanding of the cerebrovascular mechanisms of long COVID is essential to advance targeted treatments and mitigate its long-term neurocognitive consequences.

The global prevalence of depression, anxiety, and sleep disorder among patients coping with Post COVID-19 syndrome (long COVID): a systematic review and meta-analysis

BACKGROUND

Post COVID-19 syndrome, also known as "Long COVID," is a complex and multifaceted condition that affects individuals who have recovered from SARS-CoV-2 infection. This systematic review and meta-analysis aim to comprehensively assess the global prevalence of depression, anxiety, and sleep disorder in individuals coping with Post COVID-19 syndrome.

METHODS

A rigorous search of electronic databases was conducted to identify original studies until 24 January 2023. The inclusion criteria comprised studies employing previously validated assessment tools for depression, anxiety, and sleep disorders, reporting prevalence rates, and encompassing patients of all age groups and geographical regions for subgroup analysis Random effects model was utilized for the meta-analysis. Meta-regression analysis was done.

RESULTS

The pooled prevalence of depression and anxiety among patients coping with Post COVID-19 syndrome was estimated to be 23% (95% CI: 20%-26%; I2 = 99.9%) based on data from 143 studies with 7,782,124 participants and 132 studies with 9,320,687 participants, respectively. The pooled prevalence of sleep disorder among these patients, derived from 27 studies with 15,362 participants, was estimated to be 45% (95% CI: 37%-53%; I2 = 98.7%). Subgroup analyses based on geographical regions and assessment scales revealed significant variations in prevalence rates. Meta-regression analysis showed significant correlations between the prevalence and total sample size of studies, the age of participants, and the percentage of male participants. Publication bias was assessed using Doi plot visualization and the Peters test, revealing a potential source of publication bias for depression (p = 0.0085) and sleep disorder (p = 0.02). However, no evidence of publication bias was found for anxiety (p = 0.11).

CONCLUSION

This systematic review and meta-analysis demonstrate a considerable burden of mental health issues, including depression, anxiety, and sleep disorders, among individuals recovering from COVID-19. The findings emphasize the need for comprehensive mental health support and tailored interventions for patients experiencing persistent symptoms after COVID-19 recovery.

Mononeuropathy Multiplex After Severe SARS-CoV-2 Infection: A Case Series and Literature Review

INTRODUCTION

Peripheral nerve injuries are being increasingly recognized in patients recovering from severe SARS-CoV-2 infections. Axonal neuropathies can occur, leading to lasting and disabling deficits.

CASE REPORTS

We present the cases of 3 patients who developed weakness and sensory symptoms after severe SARS-CoV-2 pneumonia. The clinical deficits revealed various patterns of injury including a mononeuropathy multiplex (MNM) in the first patient, a brachial plexopathy with superimposed MNM in the second patient, and a mononeuropathy superimposed on a polyneuropathy in the third patient. Electrodiagnostic studies revealed axonopathies. The patients with MNM were left with severe disability. The third patient returned to his baseline level of functioning.

CONCLUSIONS

Severe SARS-CoV-2 infections can result in disabling axonopathies. Possible explanations include ischemic nerve damage from the profound inflammatory response and traumatic nerve injuries in the ICU setting. Preventing severe disease through vaccination and antivirals may therefore help reduce neurologic morbidity.

Neuroimmunological Effect of Vitamin D on Neuropsychiatric Long COVID Syndrome: A Review

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the causative agent of the coronavirus disease 2019 (COVID-19). COVID-19 is now recognized as a multiorgan disease with a broad spectrum of manifestations. A substantial proportion of individuals who have recovered from COVID-19 are experiencing persistent, prolonged, and often incapacitating sequelae, collectively referred to as long COVID. To date, definitive diagnostic criteria for long COVID diagnosis remain elusive. An emerging public health threat is neuropsychiatric long COVID, encompassing a broad range of manifestations, such as sleep disturbance, anxiety, depression, brain fog, and fatigue. Although the precise mechanisms underlying the neuropsychiatric complications of long COVID are presently not fully elucidated, neural cytolytic effects, neuroinflammation, cerebral microvascular compromise, breakdown of the blood-brain barrier (BBB), thrombosis, hypoxia, neurotransmitter dysregulation, and provoked neurodegeneration are pathophysiologically linked to long-term neuropsychiatric consequences, in addition to systemic hyperinflammation and maladaptation of the renin-angiotensin-aldosterone system. Vitamin D, a fat-soluble secosteroid, is a potent immunomodulatory hormone with potential beneficial effects on anti-inflammatory responses, neuroprotection, monoamine neurotransmission, BBB integrity, vasculometabolic functions, gut microbiota, and telomere stability in different phases of SARS-CoV-2 infection, acting through both genomic and nongenomic pathways. Here, we provide an up-to-date review of the potential mechanisms and pathophysiology of neuropsychiatric long COVID syndrome and the plausible neurological contributions of vitamin D in mitigating the effects of long COVID.

Role of the Renin-Angiotensin System in Long COVID's Cardiovascular Injuries

The renin-angiotensin system (RAS) is one of the biggest challenges of cardiovascular medicine. The significance of the RAS in the chronic progression of SARS-CoV-2 infection and its consequences is one of the topics that are currently being mostly discussed. SARS-CoV-2 undermines the balance between beneficial and harmful RAS pathways. The level of soluble ACE2 and membrane-bound ACE2 are both upregulated by the endocytosis of the SARS-CoV-2/ACE2 complex and the tumor necrosis factor (TNF)-α-converting enzyme (ADAM17)-induced cleavage. Through the link between RAS and the processes of proliferation, the processes of fibrous remodelling of the myocardium are initiated from the acute phase of the disease, continuing into the long COVID stage. In the long term, RAS dysfunction may cause an impairment of its beneficial effects leading to thromboembolic processes and a reduction in perfusion of target organs. The main aspects of ACE2-a key pathogenic role in COVID-19 as well as the mechanisms of RAS involvement in COVID cardiovascular injuries are studied. Therapeutic directions that can be currently anticipated in relation to the various pathogenic pathways of progression of cardiovascular damage in patients with longCOVID have also been outlined.

Neuropsychiatric aspects of long COVID: A comprehensive review

Although some patients have persistent symptoms or develop new symptoms following coronavirus disease 2019 (COVID-19) infection, neuropsychiatric aspects of long COVID are not well known. This review summarizes and provides an update on the neuropsychiatric dimensions of long COVID. Its neuropsychiatric manifestations commonly include fatigue, cognitive impairment, sleep disorders, depression, anxiety, and post-traumatic stress disorder. There are no specific tests for long COVID, but some characteristic findings such as hypometabolism on positron emission tomography have been reported. The possible mechanisms of long COVID include inflammation, ischemic effects, direct viral invasion, and social and environmental changes. Some patient characteristics and the severity and complications of acute COVID-19 infection may be associated with an increased risk of neuropsychiatric symptoms. Long COVID may resolve spontaneously or persist, depending on the type of neuropsychiatric symptoms. Although established treatments are lacking, various psychological and pharmacological treatments have been attempted. Vaccination against COVID-19 infection plays a key role in the prevention of long coronavirus disease. With differences among the SARS-CoV-2 variants, including the omicron variant, the aspects of long COVID are likely to change in the future. Further studies clarifying the aspects of long COVID to develop effective treatments are warranted.

Psychological and Cognitive Effects of Long COVID: A Narrative Review Focusing on the Assessment and Rehabilitative Approach

Long COVID is a clinical syndrome characterized by profound fatigue, neurocognitive difficulties, muscle pain, weakness, and depression, lasting beyond the 3–12 weeks following infection with SARS-CoV-2. Among the symptoms, neurocognitive and psychiatric sequelae, including attention and memory alterations, as well as anxiety and depression symptoms, have become major targets of current healthcare providers given the significant public health impact. In this context, assessment tools play a crucial role in the early screening of cognitive alterations due to Long COVID. Among others, the general cognitive assessment tools, such as the Montreal Cognitive assessment, and more specific ones, including the State Trait Inventory of Cognitive Fatigue and the Digit Span, may be of help in investigating the main neurocognitive alterations. Moreover, appropriate neurorehabilitative programs using specific methods and techniques (conventional and/or advanced) through a multidisciplinary team are required to treat COVID-19-related cognitive and behavioral abnormalities. In this narrative review, we sought to describe the main neurocognitive and psychiatric symptoms as well as to provide some clinical advice for the assessment and treatment of Long COVID.

SARS-CoV-2 and COVID-19: A Narrative Review

The World Health Organisation has reported that the viral disease known as COVID-19, caused by SARS-CoV-2, is the leading cause of death by a single infectious agent. This narrative review examines certain components of the pandemic: its origins, early clinical data, global and UK-focussed epidemiology, vaccination, variants, and long COVID.

Mechanisms of coronavirus infectious disease 2019-related neurologic diseases

PURPOSE OF REVIEW

As of January 8, 2022, a global pandemic caused by infection with severe acute respiratory syndrome coronavirus (SARS-CoV)-2, a new RNA virus, has resulted in 304,896,785 cases in over 222 countries and regions, with over 5,500,683 deaths (www.worldometers.info/coronavirus/). Reports of neurological and psychiatric symptoms in the context of coronavirus infectious disease 2019 (COVID-19) range from headache, anosmia, and dysgeusia, to depression, fatigue, psychosis, seizures, delirium, suicide, meningitis, encephalitis, inflammatory demyelination, infarction, and acute hemorrhagic necrotizing encephalopathy. Moreover, 30-50% of COVID-19 survivors develop long-lasting neurologic symptoms, including a dysexecutive syndrome, with inattention and disorientation, and/or poor movement coordination. Detection of SARS-CoV-2 RNA within the central nervous system (CNS) of patients is rare, and mechanisms of neurological damage and ongoing neurologic diseases in COVID-19 patients are unknown. However, studies demonstrating viral glycoprotein effects on coagulation and cerebral vasculature, and hypoxia- and cytokine-mediated coagulopathy and CNS immunopathology suggest both virus-specific and neuroimmune responses may be involved. This review explores potential mechanistic insights that could contribute to COVID-19-related neurologic disease.

RECENT FINDINGS

While the development of neurologic diseases during acute COVID-19 is rarely associated with evidence of viral neuroinvasion, new evidence suggests SARS-CoV-2 Spike (S) protein exhibits direct inflammatory and pro-coagulation effects. This, in conjunction with immune dysregulation resulting in cytokine release syndrome (CRS) may result in acute cerebrovascular or neuroinflammatory diseases. Additionally, CRS-mediated loss of blood-brain barrier integrity in specific brain regions may contribute to the expression of proinflammatory mediators by neural cells that may impact brain function long after resolution of acute infection. Importantly, host co-morbid diseases that affect vascular, pulmonary, or CNS function may contribute to the type of neurologic disease triggered by SARS-COV-2 infection.

SUMMARY

Distinct effects of SARS-CoV-2 S protein and CNS compartment- and region-specific responses to CRS may underlie acute and chronic neuroinflammatory diseases associated with COVID-19.