Age-Associated Neurological Complications of COVID-19: A Systematic Review and Meta-Analysis

Neuropathogenesis of SARS-CoV-2 in human neuronal, microglial and glial cells

Neurological complications, both acute and chronic, are reported commonly in COVID-19 affected individuals. In this context, the understanding of pathogenesis of SARS-CoV-2 in specific cells of central nervous system (CNS) origin is relevant. The present study explores infection biology of a clinical isolate of SARS-CoV-2 in human cell lines of neural origin such as the glioblastoma (U87-MG), neuroblastoma (SHSY5Y) and microglia (C20). Despite showing clear evidence of infection by immunofluorescence with an anti-spike protein antibody, all the three neural cell lines were observed to be highly restrictive to the replication of the infecting virus. While the U87-MG glioblastoma cells demonstrated no cytopathic effects and a low viral titre with no signs of replication, the SHSY5Y neuroblastoma cells exhibited cytopathic effects with bleb formation but no evidence of viable virus. The C20 microglial cells showed neither signs of cytopathic effects nor viable virus. Ultrastructural studies demonstrated intracellular virions in infected neural cells. The presence of lipid droplets in infected SHSY5Y cells suggested an impact on host cell metabolism. The decrease in viral RNA levels over time in all the neural cell lines suggested restricted viral replication. In conclusion, this study highlights the limited susceptibility of neural cells to SARS-CoV-2 infection. This reduced permissibility of neural cell lines to SARS-CoV-2 may point to their inherent lower expression of receptors that support viral entry in addition to the intracellular factors that potently inhibit viral replication. The study findings prompt further investigation into the mechanisms of SARS-CoV-2 infection of neural cells.

Caveolin-1 mediates blood-brain barrier permeability, neuroinflammation, and cognitive impairment in SARS-CoV-2 infection

Blood-brain barrier (BBB) permeability can cause neuroinflammation and cognitive impairment. Caveolin-1 (Cav-1) critically regulates BBB permeability, but its influence on the BBB and consequent neurological outcomes in respiratory viral infections is unknown. We used Cav-1-deficient mice with genetically encoded fluorescent endothelial tight junctions to determine how Cav-1 influences BBB permeability, neuroinflammation, and cognitive impairment following respiratory infection with mouse adapted (MA10) SARS-CoV-2 as a model for COVID-19. We found that SARS-CoV-2 infection increased brain endothelial Cav-1 and increased transcellular BBB permeability to albumin, decreased paracellular BBB Claudin-5 tight junctions, and caused T lymphocyte infiltration in the hippocampus, a region important for learning and memory. Concordantly, we observed learning and memory deficits in SARS-CoV-2 infected mice. Importantly, genetic deficiency in Cav-1 attenuated transcellular BBB permeability and paracellular BBB tight junction losses, T lymphocyte infiltration, and gliosis induced by SARS-CoV-2 infection. Moreover, Cav-1 KO mice were protected from the learning and memory deficits caused by SARS-CoV-2 infection. These results establish the contribution of Cav-1 to BBB permeability and behavioral dysfunction induced by SARS-CoV-2 neuroinflammation.

Retrospective analysis of COVID-19 patients with Guillain-Barre, Miller-Fisher, and opsoclonus-myoclonus-ataxia syndromes-a case series

BACKGROUND

In accordance with the rising number of SARS-CoV‑2 infections, reports of neurological complications have also increased. They include cerebrovascular diseases but also immunological diseases such as Guillain-Barre syndrome (GBS), Miller-Fisher syndrome (MFS), and opsoclonus-myoclonus-ataxia syndrome (OMAS). While GBS and MFS are typical postinfectious complications, OMAS has only recently been described in the context of COVID-19. GBS, MFS, and OMAS can occur as para- and postinfectious, with different underlying pathomechanisms depending on the time of neurological symptom onset. The study aimed to describe clinical features, time between infection and onset of neurological symptoms, and outcome for these diseases.

METHODS

All COVID-19 patients treated in the neurological ward between January 2020 and December 2022 were screened for GBS, MFS, and OMAS. The clinical features of all patients, with a particular focus on the time of onset of neurological symptoms, were analyzed.

RESULTS

This case series included 12 patients (7 GBS, 2 MFS, 3 OMAS). All GBS and one MFS patient received immunomodulatory treatment. Three patients (2 GBS, 1 OMAS) had a severe COVID-19 infection and received mechanical ventilation. In patients with OMAS, only one patient received treatment with intravenous immunoglobulin and cortisone. The remaining two patients, both with disease onset concurrent with SARS-COV‑2 infection, recovered swiftly without treatment. In all subgroups, patients with concurrent onset of neurological symptoms and COVID-19 infection showed a trend toward shorter disease duration.

CONCLUSION

All patient groups displayed a shorter disease duration if the onset of neurological symptoms occurred shortly after the COVID-19 diagnosis. In particular, both the OMAS patients with symptom onset concurrent with COVID-19 showed only abortive symptoms followed by a swift recovery. This observation would suggest different pathomechanisms for immune-mediated diseases depending on the time of onset after an infection.

Antigen non-specific CD8+ T cells accelerate cognitive decline in aged mice following respiratory coronavirus infection

Primarily a respiratory infection, numerous patients infected with SARS-CoV-2 present with neurologic symptoms, some continuing long after viral clearance as a persistent symptomatic phase termed "long COVID". Advanced age increases the risk of severe disease, as well as incidence of long COVID. We hypothesized that perturbations in the aged immune response predispose elderly individuals to severe coronavirus infection and post-infectious sequelae. Using a murine model of respiratory coronavirus, mouse hepatitis virus strain A59 (MHV-A59), we found that aging increased clinical illness and lethality to MHV infection, with aged animals harboring increased virus in the brain during acute infection. This was coupled with an unexpected increase in activated CD8+ T cells within the brains of aged animals but reduced antigen specificity of those CD8+ T cells. Aged animals demonstrated spatial learning impairment following MHV infection, which correlated with increased neuronal cell death and reduced neuronal regeneration in aged hippocampus. Using primary cell culture, we demonstrated that activated CD8+ T cells induce neuronal death, independent of antigen-specificity. Specifically, higher levels of CD8+ T cell-derived IFN-γ correlated with neuronal death. These results support the evidence that CD8+ T cells in the brain directly contribute to cognitive dysfunction following coronavirus infection in aged individuals.

Mild Neurological Manifestations Associated With Severe Acute Respiratory Syndrome Coronavirus 2 Infection in Hospitalized Children During the Omicron Wave in Singapore: A Retrospective Cohort Review

BACKGROUND

Neurological complications with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) omicron variant have been reported in adults; however, there are little data in the pediatric population. We aimed to report on the prevalence and clinical characteristics of children with neurological symptoms during the SARS-CoV-2 omicron wave.

METHODS

This was a single-center, retrospective cohort review of children (<18 years old) hospitalized for SARS-CoV-2 infection from December 2, 2021, to June 30, 2022.

RESULTS

During the study period, 455 children (mean age 4.8 years, range 0.67 to 18, male 58.9%) were hospitalized with SARS-CoV-2 infection. A total of 108 (23.7%) children experienced neurological symptoms; most common were seizures (62.0%), headaches (32.4%) and giddiness (14.8%). Seizures included febrile seizures (64.1%), acute symptomatic seizures (17.9%), and breakthrough seizures in known epileptics (17.9%). Children with neurological manifestations were older (7.3 vs 4.0 years, P < 0.00001), more likely to have underlying epilepsy (9.3% vs 1.2%, P = 0.0002) or neurodevelopmental disorders (17.6% vs 1.7%, P < 0.00001), and presented earlier in their illness (2.1 vs 2.8 days, P < 0.00001), compared with those without neurological manifestations. Neurological symptoms fully resolved in all but one patient at discharge. There were no mortalities and no difference in duration of hospitalization (3.1 vs 3.7 days, P = 0.5) between the groups.

CONCLUSIONS

One in four hospitalized children with SARS-CoV-2 infection when omicron variant was dominant experienced mild neurological symptoms. Overall risk factors for neurological symptoms associated with SARS-CoV-2 included older age, pre-existing febrile seizures/epilepsy and neurodevelopmental disorders.

Recapitulation of pathophysiological features of AD in SARS-CoV-2-infected subjects

Infection with the etiological agent of COVID-19, SARS-CoV-2, appears capable of impacting cognition in some patients with post-acute sequelae of SARS-CoV-2 (PASC). To evaluate neuropathophysiological consequences of SARS-CoV-2 infection, we examine transcriptional and cellular signatures in the Brodmann area 9 (BA9) of the frontal cortex and the hippocampal formation (HF) in SARS-CoV-2, Alzheimer's disease (AD), and SARS-CoV-2-infected AD individuals compared to age- and gender-matched neurological cases. Here, we show similar alterations of neuroinflammation and blood-brain barrier integrity in SARS-CoV-2, AD, and SARS-CoV-2-infected AD individuals. Distribution of microglial changes reflected by the increase in Iba-1 reveals nodular morphological alterations in SARS-CoV-2-infected AD individuals. Similarly, HIF-1α is significantly upregulated in the context of SARS-CoV-2 infection in the same brain regions regardless of AD status. The finding may help in informing decision-making regarding therapeutic treatments in patients with neuro-PASC, especially those at increased risk of developing AD.

Erythrocytes Functionality in SARS-CoV-2 Infection: Potential Link with Alzheimer's Disease

Coronavirus disease 2019 (COVID-19) is a rapidly spreading acute respiratory infection caused by SARS-CoV-2. The pathogenesis of the disease remains unclear. Recently, several hypotheses have emerged to explain the mechanism of interaction between SARS-CoV-2 and erythrocytes, and its negative effect on the oxygen-transport function that depends on erythrocyte metabolism, which is responsible for hemoglobin-oxygen affinity (Hb-O2 affinity). In clinical settings, the modulators of the Hb-O2 affinity are not currently measured to assess tissue oxygenation, thereby providing inadequate evaluation of erythrocyte dysfunction in the integrated oxygen-transport system. To discover more about hypoxemia/hypoxia in COVID-19 patients, this review highlights the need for further investigation of the relationship between biochemical aberrations in erythrocytes and oxygen-transport efficiency. Furthermore, patients with severe COVID-19 experience symptoms similar to Alzheimer's, suggesting that their brains have been altered in ways that increase the likelihood of Alzheimer's. Mindful of the partly assessed role of structural, metabolic abnormalities that underlie erythrocyte dysfunction in the pathophysiology of Alzheimer's disease (AD), we further summarize the available data showing that COVID-19 neurocognitive impairments most probably share similar patterns with known mechanisms of brain dysfunctions in AD. Identification of parameters responsible for erythrocyte function that vary under SARS-CoV-2 may contribute to the search for additional components of progressive and irreversible failure in the integrated oxygen-transport system leading to tissue hypoperfusion. This is particularly relevant for the older generation who experience age-related disorders of erythrocyte metabolism and are prone to AD, and provide an opportunity for new personalized therapies to control this deadly infection.

Molecular and cellular similarities in the brain of SARS-CoV-2 and Alzheimer's disease individuals

Infection with the etiological agent of COVID-19, SARS-CoV-2, appears capable of impacting cognition, which some patients with Post-acute Sequelae of SARS-CoV-2 (PASC). To evaluate neuro-pathophysiological consequences of SARS-CoV-2 infection, we examine transcriptional and cellular signatures in the Broadman area 9 (BA9) of the frontal cortex and the hippocampal formation (HF) in SARS-CoV-2, Alzheimer's disease (AD) and SARS-CoV-2 infected AD individuals, compared to age- and gender-matched neurological cases. Here we show similar alterations of neuroinflammation and blood-brain barrier integrity in SARS-CoV-2, AD, and SARS-CoV-2 infected AD individuals. Distribution of microglial changes reflected by the increase of Iba-1 reveal nodular morphological alterations in SARS-CoV-2 infected AD individuals. Similarly, HIF-1α is significantly upregulated in the context of SARS-CoV-2 infection in the same brain regions regardless of AD status. The finding may help to inform decision-making regarding therapeutic treatments in patients with neuro-PASC, especially those at increased risk of developing AD.

TEASER

SARS-CoV-2 and Alzheimer's disease share similar neuroinflammatory processes, which may help explain neuro-PASC.

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

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

Neuro-Immune Interactions in Severe COVID-19 Infection

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

Role of aging in Blood-Brain Barrier dysfunction and susceptibility to SARS-CoV-2 infection: impacts on neurological symptoms of COVID-19

COVID-19, which is caused by Severe Acute Respiratory Syndrome Corona Virus 2 (SARS-CoV-2), has resulted in devastating morbidity and mortality worldwide due to lethal pneumonia and respiratory distress. In addition, the central nervous system (CNS) is well documented to be a target of SARS-CoV-2, and studies detected SARS-CoV-2 in the brain and the cerebrospinal fluid of COVID-19 patients. The blood-brain barrier (BBB) was suggested to be the major route of SARS-CoV-2 infection of the brain. Functionally, the BBB is created by an interactome between endothelial cells, pericytes, astrocytes, microglia, and neurons, which form the neurovascular units (NVU). However, at present, the interactions of SARS-CoV-2 with the NVU and the outcomes of this process are largely unknown. Moreover, age was described as one of the most prominent risk factors for hospitalization and deaths, along with other comorbidities such as diabetes and co-infections. This review will discuss the impact of SARS-CoV-2 on the NVU, the expression profile of SARS-CoV-2 receptors in the different cell types of the CNS and the possible role of aging in the neurological outcomes of COVID-19. A special emphasis will be placed on mitochondrial functions because dysfunctional mitochondria are also a strong inducer of inflammatory reactions and the "cytokine storm" associated with SARS-CoV-2 infection. Finally, we will discuss possible drug therapies to treat neural endothelial function in aged patients, and, thus, alleviate the neurological symptoms associated with COVID-19.

Effect of COVID-19 Lockdowns on Eye Emergency Department, Increasing Prevalence of Uveitis and Optic Neuritis in the COVID-19 Era

Background: The COVID-19 pandemic led to the reorganization of the health care system. A decline in health- and life-saving procedures has been reported in various medical specialties. However, data on ophthalmic emergencies during lockdowns is limited. Methods: We conducted a retrospective, observational, case-control study of 2351 patients registered at the ophthalmic emergency department of a tertiary hospital in Poland during three national COVID-19 lockdowns (March/April 2020, November 2020, and March/April 2021) and corresponding months in 2019. Results: The total number of visits declined from a mean of 720/month in the non-COVID era to 304/month during COVID-19 lockdowns (p < 0.001). Ocular trauma incidence dropped significantly from 2019 (non-COVID months) to 2020/2021 (COVID group mean 201 vs. 97 patients monthly, respectively, p = 0.03). Of note, the percentage of foreign bodies removal was significantly higher during lockdowns than corresponding time in the non-COVID era. A downward trend for vitreous detachment and macular disorders cases was observed between COVID and non-COVID time. Uveitis and optic neuritis patients were seen more often during lockdowns (p < 0.001 and p = 0.0013, respectively). In contrast, the frequency of conjunctivitis and keratitis, potentially COVID-related problems, decreased significantly in COVID-19 time (mean 138 vs. 23 per month in non-COVID vs. COVID lockdowns, respectively, p < 0.001). Conclusions: The overall number of eye emergency visits declined during COVID-19 lockdowns. Conjunctivitis and keratitis rates dropped during the lockdowns. Interestingly, the frequency of immune-mediated ocular conditions (uveitis, optic neuritis) increased significantly which might be triggered by SARS-CoV2 infection.

Acute Neurologic Complications of COVID-19 and Postacute Sequelae of COVID-19

Neurologic complications can be seen in mild to severe COVID-19 with a higher risk in patients with severe COVID-19. These can occur as a direct consequence of viral infection or consequences of treatments. The spectrum ranges from non-life-threatening, like headache, fatigue, malaise, anosmia, dysgeusia, to life-threatening complications, like stroke, encephalitis, coma, Guillain-Barre syndrome. A high index of suspicion can aid in early recognition and treatment. Outcomes depend on severity of underlying COVID-19, patient age, comorbidities, and severity of the complication. Postacute sequelae of COVID-19 range from fatigue, headache, dysosmia, brain fog, anxiety, depression to an overlap with postintensive care syndrome.

Pregnancy and neurologic complications of COVID-19: A scoping review

While neurologic complications are frequently reported among patients with COVID‐19 in the general population, they are unknown in pregnant women. This paper summarizes the case reports of pregnant women with confirmed SARS‐CoV‐2 infection plus a specified neurologic diagnosis. Until November 2021, 18 case reports were found. Both the central and peripheral nervous systems were equally affected: delirium (n = 1), posterior reversible encephalopathy syndrome (n = 4), cerebrovascular disease (n = 2), acute cerebral demyelinating disease (n = 1), acute necrotizing encephalopathy (n = 1), Guillain–Barré syndrome (n = 5), including one patient who also had vestibular neuritis, Bell's palsy (n = 3), and rhabdomyolysis (n = 1). The median maternal age was 32.5 (25—35) years, the median gestational age was 34 (30—36.5) weeks, and 38.9% presented previous medical conditions. Respiratory symptoms were reported in 76.5%, and 76.5% received immunotherapies to treat the COVID‐19 or the neurologic complications. Half the women required admission to ICU and, more often, were those with central nervous system involvement (77.8% vs. 22.2%; Chi‐square test, p = .018). For 64.7% of women, the most common method of delivery was surgical, although just one case was due to the neurologic complication. There were reports of one spontaneous abortion, two fetal deaths, and no maternal deaths. Only one case presented a poor neurologic outcome. It is possible that our findings are underestimated, considering that there are thousands of reports regarding neurologic complications in the general population with COVID‐19.

Neuropathology and virus in brain of SARS-CoV-2 infected non-human primates

Neurological manifestations are a significant complication of coronavirus disease (COVID-19), but underlying mechanisms aren’t well understood. The development of animal models that recapitulate the neuropathological findings of autopsied brain tissue from patients who died from severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection are critical for elucidating the neuropathogenesis of infection and disease. Here, we show neuroinflammation, microhemorrhages, brain hypoxia, and neuropathology that is consistent with hypoxic-ischemic injury in SARS-CoV-2 infected non-human primates (NHPs), including evidence of neuron degeneration and apoptosis. Importantly, this is seen among infected animals that do not develop severe respiratory disease, which may provide insight into neurological symptoms associated with “long COVID”. Sparse virus is detected in brain endothelial cells but does not associate with the severity of central nervous system (CNS) injury. We anticipate our findings will advance our current understanding of the neuropathogenesis of SARS-CoV-2 infection and demonstrate SARS-CoV-2 infected NHPs are a highly relevant animal model for investigating COVID-19 neuropathogenesis among human subjects.

COVID-19 can result in neurological manifestations and animal models could provide insights into the mechanisms. Here, the authors describe neuroinflammation, microhemorrhages and brain hypoxia in SARS-CoV-2 infected non-human primates, including in animals that don’t develop severe respiratory disease.

SARS-CoV-2 interacts with renin-angiotensin system: impact on the central nervous system in elderly patients

SARS-CoV-2 is a recently identified coronavirus that causes the current pandemic disease known as COVID-19. SARS-CoV-2 uses angiotensin-converting enzyme 2 (ACE2) as a receptor, suggesting that the initial steps of SARS-CoV-2 infection may have an impact on the renin-angiotensin system (RAS). Several processes are influenced by RAS in the brain. The neurological symptoms observed in COVID-19 patients, including reduced olfaction, meningitis, ischemic stroke, cerebral thrombosis, and delirium, could be associated with RAS imbalance. In this review, we focus on the potential role of disturbances in the RAS as a cause for central nervous system sequelae of SARS-CoV-2 infection in elderly patients.

Impact of SARS-CoV-2 Infection in Patients with Neurological Pathology

The COVID-19 disease, caused by infection with SARS-CoV-2, rapidly transformed into a pandemic following its emergence, and it continues to affect the population at a global level. This disease is associated with high mortality rates and mainly affects the pulmonary spectrum, with signs of interstitial pneumonia or other pathological modifications. Signs indicative of SARS-CoV-2 infection can be observed using pulmonary radiography or computed tomography scans and are closely linked to acute respiratory distress; however, there is accumulating evidence that the virus affects the central nervous system. Several symptoms, such as headaches, cough, fatigue, myalgia, ageusia, and anosmia, have also been reported along with neurological syndromes such as stroke, encephalopathy, Guillain–Barre syndrome, convulsions, and coma; the most frequent associated complication is ischemic stroke. Diagnosis of infection with SARS-CoV-2 virus is based on a positive RT-PCR test. Imaging investigations, such as thoracic computed tomography scans, are not used to diagnose COVID-19, monitor for pulmonary disease, or follow dynamic disease evolution, but they may be used in the case of a negative RT-PCR test. This paper presents the research performed on a group of 150 cases of patients affected by neurological disorders and that were subsequently confirmed to be infected with SARS-CoV-2, which was carried out over a period of 10 months within the Neurology Department and Laboratory of Magnetic Resonance Imaging of “Sf. Andrei” Emergency Hospital in Constanta. The collected data are observational and provide perspectives on the neurological pathology associated with the SARS-CoV-2 virus, and on the frequently associated risk factors, associated comorbidities, and the ages of patients who were affected by the virus, as well as the clinical and paraclinical manifestations of the patients admitted to the hospital’s neurology department.

Covid-19, nervous system pathology, and Parkinson's disease: Bench to bedside

Coronavirus disease 2019 (Covid-19) caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection is primarily regarded as a respiratory disease; however, multisystemic involvement accompanied by a variety of clinical manifestations, including neurological symptoms, are commonly observed. There is, however, little evidence supporting SARS-CoV-2 infection of central nervous system cells, and neurological symptoms for the most part appear to be due to damage mediated by hypoxic/ischemic and/or inflammatory insults. In this chapter, we report evidence on candidate neuropathological mechanisms underlying neurological manifestations in Covid-19, suggesting that while there is mostly evidence against SARS-CoV-2 entry into brain parenchymal cells as a mechanism that may trigger Parkinson's disease and parkinsonism, that there are multiple means by which the virus may cause neurological symptoms.

Brain MRI and neuropsychological findings at long-term follow-up after COVID-19 hospitalisation: an observational cohort study

OBJECTIVES

To report findings on brain MRI and neurocognitive function, as well as persisting fatigue at long-term follow-up after COVID-19 hospitalisation in patients identified as high risk for affection of the central nervous system.

DESIGN

Ambidirectional observational cohort study.

SETTING

All 734 patients from a regional population in Sweden with a laboratory-confirmed COVID-19 diagnosis admitted to hospital during the period 1 March to 31 May 2020.

PARTICIPANTS

A subgroup (n=185) with persisting symptoms still interfering with daily life at a telephone follow-up 4 months after discharge were invited for a medical and neuropsychological evaluation. Thirty-five of those who were assessed with a neurocognitive test battery at the clinical visit, and presented a clinical picture concerning for COVID-19-related brain pathology, were further investigated by brain MRI.

MAIN OUTCOME MEASURES

Findings on brain MRI, neurocognitive test results and reported fatigue.

RESULTS

Twenty-five patients (71%) had abnormalities on MRI; multiple white matter lesions were the most common finding. Sixteen patients (46%) demonstrated impaired neurocognitive function, of which 10 (29%) had severe impairment. Twenty-six patients (74%) reported clinically significant fatigue. Patients with abnormalities on MRI had a lower Visuospatial Index (p=0.031) compared with the group with normal MRI findings.

CONCLUSIONS

In this group of patients selected to undergo MRI after a clinical evaluation, a majority of patients had abnormal MRI and/or neurocognitive test results. Abnormal findings were not restricted to patients with severe disease.

Adulthood systemic inflammation accelerates the trajectory of age-related cognitive decline

In order to understand the long-term effects of systemic inflammation, it is important to distinguish inflammation-induced changes in baseline cognitive function from changes that interact with aging to influence the trajectory of cognitive decline. Lipopolysaccharide (LPS; 1 mg/kg) or vehicle was administered to young adult (6 months) male rats via intraperitoneal injections, once a week for 7 weeks. Longitudinal effects on cognitive decline were examined 6 and 12 months after the initial injections. Repeated LPS treatment, in adults, resulted in a long-term impairment in memory, examined in aged animals (age 18 months), but not in middle-age (age 12 months). At 12 months following injections, LPS treatment was associated with a decrease in N-methyl-D-aspartate receptor-mediated component of synaptic transmission and altered expression of genes linked to the synapse and to regulation of the response to inflammatory signals. The results of the current study suggest that the history of systemic inflammation is one component of environmental factors that contribute to the resilience or susceptibility to age-related brain changes and associated trajectory of cognitive decline.