New challenges from Covid-19 pandemic: an unexpected opportunity to enlighten the link between viral infections and brain disorders?

Assessment of COVID-19-related olfactory dysfunction and its association with psychological, neuropsychiatric, and cognitive symptoms

Purpose of review

To provide a detailed overview of the assessment of COVID-19-related olfactory dysfunction and its association with psychological, neuropsychiatric, and cognitive symptoms.

Recent findings

COVID-19-related olfactory dysfunction can have a detrimental impact to the quality of life of patients. Prior to the COVID-19 pandemic, olfactory and taste disorders were a common but under-rated, under-researched and under-treated sensory loss. The pandemic has exacerbated the current unmet need for accessing good healthcare for patients living with olfactory disorders and other symptoms secondary to COVID-19. This review thus explores the associations that COVID-19 has with psychological, neuropsychiatric, and cognitive symptoms, and provide a framework and rationale for the assessment of patients presenting with COVID-19 olfactory dysfunction.

Summary

Acute COVID-19 infection and long COVID is not solely a disease of the respiratory and vascular systems. These two conditions have strong associations with psychological, neuropsychiatric, and cognitive symptoms. A systematic approach with history taking and examination particularly with nasal endoscopy can determine the impact that this has on the patient. Specific olfactory disorder questionnaires can demonstrate the impact on quality of life, while psychophysical testing can objectively assess and monitor olfaction over time. The role of cross-sectional imaging is not yet described for COVID-19-related olfactory dysfunction. Management options are limited to conservative adjunctive measures, with some medical therapies described.

COVID-19 causes neuronal degeneration and reduces neurogenesis in human hippocampus

Recent investigations of COVID-19 have largely focused on the effects of this novel virus on the vital organs in order to efficiently assist individuals who have recovered from the disease. In the present study we used hippocampal tissue samples extracted from people who died after COVID-19. Utilizing histological techniques to analyze glial and neuronal cells we illuminated a massive degeneration of neuronal cells and changes in glial cells morphology in hippocampal samples. The results showed that in hippocampus of the studied brains there were morphological changes in pyramidal cells, an increase in apoptosis, a drop in neurogenesis, and change in spatial distribution of neurons in the pyramidal and granular layer. It was also demonstrated that COVID-19 alter the morphological characteristics and distribution of astrocyte and microglia cells. While the exact mechanism(s) by which the virus causes neuronal loss and morphology in the central nervous system (CNS) remains to be determined, it is necessary to monitor the effect of SARS-CoV-2 infection on CNS compartments like the hippocampus in future investigations. As a result of what happened in the hippocampus secondary to COVID-19, memory impairment may be a long-term neurological complication which can be a predisposing factor for neurodegenerative disorders through neuroinflammation and oxidative stress mechanisms.

Experimental Models of SARS-COV-2 Infection in the Central Nervous System

Coronavirus disease 2019 (COVID-19) has raised serious concerns worldwide due to its great impact on human health and forced scientists racing to find effective therapies to control the infection and a vaccine for the virus. To this end, intense research efforts have focused on understanding the viral biology of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), responsible for COVID-19. The ever-expanding list of cases, reporting clinical neurological complications in COVID-19 patients, strongly suggests the possibility of the virus invading the nervous system. The pathophysiological processes responsible for the neurological impact of COVID-19 are not fully understood. Some neurodegenerative disorders sometimes take more than a decade to manifest, so the long-term pathophysiological outcomes of SARS-CoV-2 neurotropism should be regarded as a challenge for researchers in this field. There is no documentation on the long-term impact of SARS-CoV-2 on the human central nervous system (CNS). Most of the data relating to neurological damage during SARS-CoV-2 infection have yet to be established experimentally. The purpose of this review is to describe the knowledge gained, from experimental models, to date, on the mechanisms of neuronal invasion and the effects produced by infection. The hope is that, once the processes are understood, therapies can be implemented to limit the damage produced. Long-term monitoring and the use of appropriate and effective therapies could reduce the severity of symptoms and improve quality of life of the most severely affected patients, with a special focus on those have required hospital care and assisted respiration.

COVID-19 Worsens Chronic Lumbosacral Radicular Pain—Case Series Report

The knowledge of the COVID-19 symptomatology has increased since the beginning of the SARS-CoV-2 pandemic. The symptoms of nervous system involvement have been observed across the spectrum of COVID-19 severity. Reports describing difficulties of nerve roots are rare; the affection of brain and spinal cord by SARS-CoV-2 is of leading interest. Our aim therefore is to describe the radicular pain deterioration in the group of nine chronic lumbosacral radicular syndrome sufferers in acute COVID-19. The intensity of radicular pain was evaluated by the Visual Analogue Scale (VAS). The VAS score in acute infection increased from 5.6 ± 1.1 to 8.0 ± 1.3 (Cohen’s d = 1.99) over the course of COVID-19, indicating dramatic aggravation of pain intensity. However, the VAS score decreased spontaneously to pre-infection levels after 4 weeks of COVID-19 recovery (5.8 ± 1.1). The acute SARS-CoV-2 infection worsened the pre-existing neural root irritation symptomatology, which may be ascribed to SARS-CoV-2 radiculitis of neural roots already compressed by the previous disc herniation. These findings based on clinical observations indicate that the neurotropism of novel coronavirus infection can play an important role in the neural root irritation symptomatology deterioration in patients with chronic pre-existing lumbosacral radicular syndrome.

Does COVID-19 increase the risk of neuropsychiatric sequelae? Evidence from a mendelian randomization approach

Observational studies based on electronic health records (EHR) report an increased risk of neurological/neuropsychiatric sequelae for patients who have had coronavirus disease 2019 (COVID-19). However, these studies may suffer from biases such as unmeasured confounding, residual reverse causality, or lack of precision in EHR-based diagnoses. To rule out these biases, we tested causal links between COVID-19 and different potential neurological/neuropsychiatric sequelae through a two-sample Mendelian randomization analysis of summary statistics from large Genome-Wide Association Scans of susceptibility to COVID-19 and different neurological and neuropsychiatric disorders, including major depression, anxiety, schizophrenia, stroke, Parkinson’s and Alzheimer’s diseases. We found robust evidence suggesting that COVID-19 – notably the hospitalized and most severe forms – carries an increased risk of neuropsychiatric sequelae, particularly Alzheimer’s disease, and to a lesser extent anxiety disorder. In line with a large longitudinal EHR-based study, this evidence was stronger for more severe COVID-19 forms. These results call for a targeted screening strategy to tackle the post-COVID neuropsychiatric pandemic.

Mental health symptoms and inflammatory markers among HIV infected patients in Tanzania

Background

HIV and mental disorders are predicted to be the leading causes of illness worldwide by the year 2030. HIV-infected patients are at increased risk of developing mental disorders which are significantly associated with negative clinical outcomes and propagation of new HIV infections. There is little evidence that links inflammation to development of mental disorders among HIV patients. Therefore, the main objective of this study was to evaluate if mental health symptoms were associated with biomarkers of inflammation in HIV infected subjects.

Methods

A cross-sectional study was conducted in Dar es Salam, Tanzania from March to May 2018. Standardized tools were used to collect data based on the World Health Organisation's (WHO) stepwise approach for non-communicable diseases (NCD) surveillance. A total of 407 HIV+ patients on antiretroviral therapy were recruited. The WHO stepwise approach for NCD surveillance was used to collect data together with anthropometric measurements. Mental health symptoms were determined based on self-reported thoughts of helplessness, suicide ideation, depression, despair, discouragement, and feelings of isolation. Enzyme-linked immunosorbent assay was used to test for inflammatory markers:- C-reactive protein (CRP), Iinterleukin-6 (IL-6), interleukin-18 (IL-18), soluble tumour necrosis factor receptor-I (sTNFR-I), and soluble tumour necrosis factor receptor-II (sTNFR-II). Bivariate and multi-variate analysis was conducted to examine the association between biomarkers and mental health symptoms.

Results

The prevalence of self-reported mental health symptoms was 42% (n = 169). Participants with self-reported symptoms of mental health had elevated CRP, were less likely to walk or use a bicycle for at least 10 minutes, were less likely to participate in moderate-intensity sports or fitness activities, and had poor adherence to HIV treatment (p < 0.005). CRP remained significant in the sex adjusted, age-sex adjusted, and age-sex-moderate exercise adjusted models. In the fully adjusted logistic regression model, self-reported mental health symptoms were significantly associated with a higher quartile of elevated CRP (OR 4.4; 95% CI 1.3–5.9) and sTNFR-II (OR 2.6; 95% CI 1.4–6.6) and the third quartile of IL-18 (OR 5.1;95% CI 1.5–17.5) as compared with those reporting no mental health symptoms. The significance of sTNFR-II and IL-18 in the fully adjusted model is confounded by viral load suppression rates at the sixth month.

Conclusion

High CRP and sTNFR II were important contributors to the prevalence of mental health symptoms. This study is among the minimal studies that have examined mental health issues in HIV, and therefore, the findings may offer significant knowledge despite the potential reverse causality. Regardless of the nature of these associations, efforts should be directed toward screening, referral, and follow-up of HIV patients who are at-risk for mental health disorders.

The chronic neuropsychiatric sequelae of COVID-19: The need for a prospective study of viral impact on brain functioning

INTRODUCTION

The increasing evidence of SARS-CoV-2 impact on the central nervous system (CNS) raises key questions on its impact for risk of later life cognitive decline, Alzheimer's disease (AD), and other dementia.

METHODS

The Alzheimer's Association and representatives from more than 30 countries-with technical guidance from the World Health Organization-have formed an international consortium to study the short-and long-term consequences of SARS-CoV-2 on the CNS-including the underlying biology that may contribute to AD and other dementias. This consortium will link teams from around the world covering more than 22 million COVID-19 cases to enroll two groups of individuals including people with disease, to be evaluated for follow-up evaluations at 6, 9, and 18 months, and people who are already enrolled in existing international research studies to add additional measures and markers of their underlying biology.

CONCLUSIONS

The increasing evidence and understanding of SARS-CoV-2's impact on the CNS raises key questions on the impact for risk of later life cognitive decline, AD, and other dementia. This program of studies aims to better understand the long-term consequences that may impact the brain, cognition, and functioning-including the underlying biology that may contribute to AD and other dementias.

Neuroinvasion, neurotropic, and neuroinflammatory events of SARS-CoV-2: understanding the neurological manifestations in COVID-19 patients

Respiratory viruses are opportunistic pathogens that infect the upper respiratory tract in humans and cause severe illnesses, especially in vulnerable populations. Some viruses have neuroinvasive properties and activate the immune response in the brain. These immune events may be neuroprotective or they may cause long-term damage similar to what is seen in some neurodegenerative diseases. The new “Severe Acute Respiratory Syndrome Coronavirus 2” (SARS-CoV-2) is one of the Respiratory viruses causing highly acute lethal pneumonia coronavirus disease 2019 (COVID-19) with clinical similarities to those reported in “Severe Acute Respiratory Syndrome Coronavirus”(SARS-CoV) and the “Middle East Respiratory Syndrome Coronavirus”(MERS-CoV) including neurological manifestation. To examine the possible neurological damage induced by SARS-CoV-2, it is necessary to understand the immune reactions to viral infection in the brain, and their short- and long-term consequences. Considering the similarities between SARS-CoV and SARS-CoV-2, which will be discussed, cooperative homological and phylogenetical studies lead us to question if SARS-CoV-2 can have similar neuroinvasive capacities and neuroinflammatiory events that may lead to the same short- and long-term neuropathologies that SARS-CoV had shown in human and animal models. To explain the neurological manifestation caused by SARS-CoV-2, we will present a literature review of 765 COVID-19 patients, in which 18% had neurological symptoms and complications, including encephalopathy, encephalitis and cerebrovascular pathologies, acute myelitis, and Guillain-Barré syndrome. Clinical studies describe anosmia or partial loss of the sense of smell as the most frequent symptom in COVID19 patients, suggesting that olfactory dysfunction and the initial ultrarapid immune responses could be a prognostic factor.