Long-term outcomes of hospitalized patients with SARS-CoV-2/COVID-19 with and without neurological involvement: 3-year follow-up assessment.

BACKGROUND: Acute neurological manifestation is a common complication of acute Coronavirus Disease 2019 (COVID-19) disease. This retrospective cohort study investigated the 3-year outcomes of patients with and without significant neurological manifestations during initial COVID-19 hospitalization. METHODS AND FINDINGS: Patients hospitalized for Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection between 03/01/2020 and 4/16/2020 in the Montefiore Health System in the Bronx, an epicenter of the early pandemic, were included. Follow-up data was captured up to 01/23/2023 (3 years post-COVID-19). This cohort consisted of 414 patients with COVID-19 with significant neurological manifestations and 1,199 propensity-matched patients (for age and COVID-19 severity score) with COVID-19 without neurological manifestations. Neurological involvement during the acute phase included acute stroke, new or recrudescent seizures, anatomic brain lesions, presence of altered mentation with evidence for impaired cognition or arousal, and neuro-COVID-19 complex (headache, anosmia, ageusia, chemesthesis, vertigo, presyncope, paresthesias, cranial nerve abnormalities, ataxia, dysautonomia, and skeletal muscle injury with normal orientation and arousal signs). There were no significant group differences in female sex composition (44.93% versus 48.21%, p = 0.249), ICU and IMV status, white, not Hispanic (6.52% versus 7.84%, p = 0.380), and Hispanic (33.57% versus 38.20%, p = 0.093), except black non-Hispanic (42.51% versus 36.03%, p = 0.019). Primary outcomes were mortality, stroke, heart attack, major adverse cardiovascular events (MACE), reinfection, and hospital readmission post-discharge. Secondary outcomes were neuroimaging findings (hemorrhage, active and prior stroke, mass effect, microhemorrhages, white matter changes, microvascular disease (MVD), and volume loss). More patients in the neurological cohort were discharged to acute rehabilitation (10.39% versus 3.34%, p < 0.001) or skilled nursing facilities (35.75% versus 25.35%, p < 0.001) and fewer to home (50.24% versus 66.64%, p < 0.001) than matched controls. Incidence of readmission for any reason (65.70% versus 60.72%, p = 0.036), stroke (6.28% versus 2.34%, p < 0.001), and MACE (20.53% versus 16.51%, p = 0.032) was higher in the neurological cohort post-discharge. Per Kaplan-Meier univariate survival curve analysis, such patients in the neurological cohort were more likely to die post-discharge compared to controls (hazard ratio: 2.346, (95% confidence interval (CI) [1.586, 3.470]; p < 0.001)). Across both cohorts, the major causes of death post-discharge were heart disease (13.79% neurological, 15.38% control), sepsis (8.63%, 17.58%), influenza and pneumonia (13.79%, 9.89%), COVID-19 (10.34%, 7.69%), and acute respiratory distress syndrome (ARDS) (10.34%, 6.59%). Factors associated with mortality after leaving the hospital involved the neurological cohort (odds ratio (OR): 1.802 (95% CI [1.237, 2.608]; p = 0.002)), discharge disposition (OR: 1.508 (95% CI [1.276, 1.775]; p < 0.001)), congestive heart failure (OR: 2.281 (95% CI [1.429, 3.593]; p < 0.001)), higher COVID-19 severity score (OR: 1.177 (95% CI [1.062, 1.304]; p = 0.002)), and older age (OR: 1.027 (95% CI [1.010, 1.044]; p = 0.002)). There were no group differences in radiological findings, except that the neurological cohort showed significantly more age-adjusted brain volume loss (p = 0.045) than controls. The study's patient cohort was limited to patients infected with COVID-19 during the first wave of the pandemic, when hospitals were overburdened, vaccines were not yet available, and treatments were limited. Patient profiles might differ when interrogating subsequent waves. CONCLUSIONS: Patients with COVID-19 with neurological manifestations had worse long-term outcomes compared to matched controls. These findings raise awareness and the need for closer monitoring and timely interventions for patients with COVID-19 with neurological manifestations, as their disease course involving initial neurological manifestations is associated with enhanced morbidity and mortality.

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.

Neurogenetic disorders across the lifespan: from aberrant development to degeneration.

Intellectual disability and autism spectrum disorder (ASD) are common, and genetic testing is increasingly performed in individuals with these diagnoses to inform prognosis, refine management and provide information about recurrence risk in the family. For neurogenetic conditions associated with intellectual disability and ASD, data on natural history in adults are scarce; however, as older adults with these disorders are identified, it is becoming clear that some conditions are associated with both neurodevelopmental problems and neurodegeneration. Moreover, emerging evidence indicates that some neurogenetic conditions associated primarily with neurodegeneration also affect neurodevelopment. In this Perspective, we discuss examples of diseases that have developmental and degenerative overlap. We propose that neurogenetic disorders should be studied continually across the lifespan to understand the roles of the affected genes in brain development and maintenance, and to inform strategies for treatment.

Nervous System-Systemic Crosstalk in SARS-CoV-2/COVID-19: A Unique Dyshomeostasis Syndrome.

SARS-CoV-2 infection is associated with a spectrum of acute neurological syndromes. A subset of these syndromes promotes higher in-hospital mortality than is predicted by traditional parameters defining critical care illness. This suggests that deregulation of components of the central and peripheral nervous systems compromises the interplay with systemic cellular, tissue and organ interfaces to mediate numerous atypical manifestations of COVID-19 through impairments in organismal homeostasis. This unique dyshomeostasis syndrome involves components of the ACE-2/1 lifecycles, renin-angiotensin system regulatory axes, integrated nervous system functional interactions and brain regions differentially sculpted by accelerated evolutionary processes and more primordial homeostatic functions. These biological contingencies suggest a mechanistic blueprint to define long-term neurological sequelae and systemic manifestations such as premature aging phenotypes, including organ fibrosis, tissue degeneration and cancer. Therapeutic initiatives must therefore encompass innovative combinatorial agents, including repurposing FDA-approved drugs targeting components of the autonomic nervous system and recently identified products of SARS-CoV-2-host interactions.

Neurologic Syndromes Predict Higher In-Hospital Mortality in COVID-19.

OBJECTIVE: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is protean in its manifestations, affecting nearly every organ system. However, nervous system involvement and its effect on disease outcome are poorly characterized. The objective of this study was to determine whether neurologic syndromes are associated with increased risk of inpatient mortality. METHODS: A total of 581 hospitalized patients with confirmed SARS-CoV-2 infection, neurologic involvement, and brain imaging were compared to hospitalized non-neurologic patients with coronavirus disease 2019 (COVID-19). Four patterns of neurologic manifestations were identified: acute stroke, new or recrudescent seizures, altered mentation with normal imaging, and neuro-COVID-19 complex. Factors present on admission were analyzed as potential predictors of in-hospital mortality, including sociodemographic variables, preexisting comorbidities, vital signs, laboratory values, and pattern of neurologic manifestations. Significant predictors were incorporated into a disease severity score. Patients with neurologic manifestations were matched with patients of the same age and disease severity to assess the risk of death. RESULTS: A total of 4,711 patients with confirmed SARS-CoV-2 infection were admitted to one medical system in New York City during a 6-week period. Of these, 581 (12%) had neurologic issues of sufficient concern to warrant neuroimaging. These patients were compared to 1,743 non-neurologic patients with COVID-19 matched for age and disease severity admitted during the same period. Patients with altered mentation (n = 258, p = 0.04, odds ratio [OR] 1.39, confidence interval [CI] 1.04-1.86) or radiologically confirmed stroke (n = 55, p = 0.001, OR 3.1, CI 1.65-5.92) had a higher risk of mortality than age- and severity-matched controls. CONCLUSIONS: The incidence of altered mentation or stroke on admission predicts a modest but significantly higher risk of in-hospital mortality independent of disease severity. While other biomarker factors also predict mortality, measures to identify and treat such patients may be important in reducing overall mortality of COVID-19.

Microglial reduction of colony stimulating factor-1 receptor expression is sufficient to confer adult onset leukodystrophy.

Adult onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP) is a dementia resulting from dominantly inherited CSF1R inactivating mutations. The Csf1r+/- mouse mimics ALSP symptoms and pathology. Csf1r is mainly expressed in microglia, but also in cortical layer V neurons that are gradually lost in Csf1r+/- mice with age. We therefore examined whether microglial or neuronal Csf1r loss caused neurodegeneration in Csf1r+/- mice. The behavioral deficits, pathologies and elevation of Csf2 expression contributing to disease, previously described in the Csf1r+/- ALSP mouse, were reproduced by microglial deletion (MCsf1rhet mice), but not by neural deletion. Furthermore, increased Csf2 expression by callosal astrocytes, oligodendrocytes, and microglia was observed in Csf1r+/- mice and, in MCsf1rhet mice, the densities of these three cell types were increased in supraventricular patches displaying activated microglia, an early site of disease pathology. These data confirm that ALSP is a primary microgliopathy and inform future therapeutic and experimental approaches.

EEG findings in acutely ill patients investigated for SARS-CoV-2/COVID-19: A small case series preliminary report.

OBJECTIVE: Acute encephalopathy may occur in COVID-19-infected patients. We investigated whether medically indicated EEGs performed in acutely ill patients under investigation (PUIs) for COVID-19 report epileptiform abnormalities and whether these are more prevalent in COVID-19 positive than negative patients. METHODS: In this retrospective case series, adult COVID-19 inpatient PUIs underwent EEGs for acute encephalopathy and/or seizure-like events. PUIs had 8-channel headband EEGs (Ceribell; 20 COVID-19 positive, 6 COVID-19 negative); 2 more COVID-19 patients had routine EEGs. Overall, 26 Ceribell EEGs, 4 routine and 7 continuous EEG studies were reviewed. EEGs were interpreted by board-certified clinical neurophysiologists (n = 16). EEG findings were correlated with demographic data, clinical presentation and history, and medication usage. Fisher's exact test was used. RESULTS: We included 28 COVID-19 PUIs (30-83 years old), of whom 22 tested positive (63.6% males) and 6 tested negative (33.3% male). The most common indications for EEG, among COVID-19-positive vs COVID-19-negative patients, respectively, were new onset encephalopathy (68.2% vs 33.3%) and seizure-like events (14/22, 63.6%; 2/6, 33.3%), even among patients without prior history of seizures (11/17, 64.7%; 2/6, 33.3%). Sporadic epileptiform discharges (EDs) were present in 40.9% of COVID-19-positive and 16.7% of COVID-19-negative patients; frontal sharp waves were reported in 8/9 (88.9%) of COVID-19-positive patients with EDs and in 1/1 of COVID-19-negative patient with EDs. No electrographic seizures were captured, but 19/22 COVID-19-positive and 6/6 COVID-19-negative patients were given antiseizure medications and/or sedatives before the EEG. SIGNIFICANCE: This is the first preliminary report of EDs in the EEG of acutely ill COVID-19-positive patients with encephalopathy or suspected clinical seizures. EDs are relatively common in this cohort and typically appear as frontal sharp waves. Further studies are needed to confirm these findings and evaluate the potential direct or indirect effects of COVID-19 on activating epileptic activity.

Microglial Homeostasis Requires Balanced CSF-1/CSF-2 Receptor Signaling.

CSF-1R haploinsufficiency causes adult-onset leukoencephalopathy with axonal spheroids and pigmented glia (ALSP). Previous studies in the Csf1r+/- mouse model of ALSP hypothesized a central role of elevated cerebral Csf2 expression. Here, we show that monoallelic deletion of Csf2 rescues most behavioral deficits and histopathological changes in Csf1r+/- mice by preventing microgliosis and eliminating most microglial transcriptomic alterations, including those indicative of oxidative stress and demyelination. We also show elevation of Csf2 transcripts and of several CSF-2 downstream targets in the brains of ALSP patients, demonstrating that the mechanisms identified in the mouse model are functional in humans. Our data provide insights into the mechanisms underlying ALSP. Because increased CSF2 levels and decreased microglial Csf1r expression have also been reported in Alzheimer's disease and multiple sclerosis, we suggest that the unbalanced CSF-1R/CSF-2 signaling we describe in the present study may contribute to the pathogenesis of other neurodegenerative conditions.

Loss-of-Huntingtin in Medial and Lateral Ganglionic Lineages Differentially Disrupts Regional Interneuron and Projection Neuron Subtypes and Promotes Huntington's Disease-Associated Behavioral, Cellular, and Pathological Hallmarks.

Emerging studies are providing compelling evidence that the pathogenesis of Huntington's disease (HD), a neurodegenerative disorder with frequent midlife onset, encompasses developmental components. Moreover, our previous studies using a hypomorphic model targeting huntingtin during the neurodevelopmental period indicated that loss-of-function mechanisms account for this pathogenic developmental component (Arteaga-Bracho et al., 2016). In the present study, we specifically ascertained the roles of subpallial lineage species in eliciting the previously observed HD-like phenotypes. Accordingly, we used the Cre-loxP system to conditionally ablate the murine huntingtin gene (Httflx) in cells expressing the subpallial patterning markers Gsx2 (Gsx2-Cre) or Nkx2.1 (Nkx2.1-Cre) in Httflx mice of both sexes. These genetic manipulations elicited anxiety-like behaviors, hyperkinetic locomotion, age-dependent motor deficits, and weight loss in both Httflx;Gsx2-Cre and Httflx;Nkx2.1-Cre mice. In addition, these strains displayed unique but complementary spatial patterns of basal ganglia degeneration that are strikingly reminiscent of those seen in human cases of HD. Furthermore, we observed early deficits of somatostatin-positive and Reelin-positive interneurons in both Htt subpallial null strains, as well as early increases of cholinergic interneurons, Foxp2+ arkypallidal neurons, and incipient deficits with age-dependent loss of parvalbumin-positive neurons in Httflx;Nkx2.1-Cre mice. Overall, our findings indicate that selective loss-of-huntingtin function in subpallial lineages differentially disrupts the number, complement, and survival of forebrain interneurons and globus pallidus GABAergic neurons, thereby leading to the development of key neurological hallmarks of HD during adult life. Our findings have important implications for the establishment and deployment of neural circuitries and the integrity of network reserve in health and disease.SIGNIFICANCE STATEMENT Huntington's disease (HD) is a progressive degenerative disorder caused by aberrant trinucleotide expansion in the huntingtin gene. Mechanistically, this mutation involves both loss- and gain-of-function mechanisms affecting a broad array of cellular and molecular processes. Although huntingtin is widely expressed during adult life, the mutant protein only causes the demise of selective neuronal subtypes. The mechanisms accounting for this differential vulnerability remain elusive. In this study, we have demonstrated that loss-of-huntingtin function in subpallial lineages not only differentially disrupts distinct interneuron species early in life, but also leads to a pattern of neurological deficits that are reminiscent of HD. This work suggests that early disruption of selective neuronal subtypes may account for the profiles of enhanced regional cellular vulnerability to death in HD.

Epigenetic mechanisms underlying nervous system diseases.

Epigenetic mechanisms act as control systems for modulating genomic structure and activity in response to evolving profiles of cell-extrinsic, cell-cell, and cell-intrinsic signals. These dynamic processes are responsible for mediating cell- and tissue-specific gene expression and function and gene-gene and gene-environmental interactions. The major epigenetic mechanisms include DNA methylation and hydroxymethylation; histone protein posttranslational modifications, nucleosome remodeling/repositioning, and higher-order chromatin reorganization; noncoding RNA regulation; and RNA editing. These mechanisms are intimately involved in executing fundamental genomic programs, including gene transcription, posttranscriptional RNA processing and transport, translation, X-chromosome inactivation, genomic imprinting, retrotransposon regulation, DNA replication, and DNA repair and the maintenance of genomic stability. For the nervous system, epigenetics offers a novel and robust framework for explaining how brain development and aging occur, neural cellular diversity is generated, synaptic and neural network connectivity and plasticity are mediated, and complex cognitive and behavioral phenotypes are inherited transgenerationally. Epigenetic factors and processes are, not surprisingly, implicated in nervous system disease pathophysiology through several emerging paradigms - mutations and genetic variation in genes encoding epigenetic factors; impairments in epigenetic factor expression, localization, and function; epigenetic mechanisms modulating disease-associated factors and pathways; and the presence of deregulated epigenetic profiles in central and peripheral tissues.

Increased localization of APP-C99 in mitochondria-associated ER membranes causes mitochondrial dysfunction in Alzheimer disease.

In the amyloidogenic pathway associated with Alzheimer disease (AD), the amyloid precursor protein (APP) is cleaved by ß-secretase to generate a 99-aa C-terminal fragment (C99) that is then cleaved by γ-secretase to generate the ß-amyloid (Aß) found in senile plaques. In previous reports, we and others have shown that γ-secretase activity is enriched in mitochondria-associated endoplasmic reticulum (ER) membranes (MAM) and that ER-mitochondrial connectivity and MAM function are upregulated in AD We now show that C99, in addition to its localization in endosomes, can also be found in MAM, where it is normally processed rapidly by γ-secretase. In cell models of AD, however, the concentration of unprocessed C99 increases in MAM regions, resulting in elevated sphingolipid turnover and an altered lipid composition of both MAM and mitochondrial membranes. In turn, this change in mitochondrial membrane composition interferes with the proper assembly and activity of mitochondrial respiratory supercomplexes, thereby likely contributing to the bioenergetic defects characteristic of AD.

A dedicated scholarly research program in an adult and pediatric neurology residency program.

OBJECTIVE: To describe and assess the effectiveness of a formal scholarly activity program for a highly integrated adult and pediatric neurology residency program. METHODS: Starting in 2011, all graduating residents were required to complete at least one form of scholarly activity broadly defined to include peer-reviewed publications or presentations at scientific meetings of formally mentored projects. The scholarly activity program was administered by the associate residency training director and included an expanded journal club, guided mentorship, a required grand rounds platform presentation, and annual awards for the most scholarly and seminal research findings. We compared scholarly output and mentorship for residents graduating within a 5-year period following program initiation (2011-2015) and during the preceding 5-year preprogram baseline period (2005-2009). RESULTS: Participation in scholarship increased from the preprogram baseline (24 of 53 graduating residents, 45.3%) to the postprogram period (47 of 57 graduating residents, 82.1%, p < 0.0001). Total scholarly output more than doubled from 49 activities preprogram (0.92/resident) to 139 postprogram (2.44/resident, p = 0.0002). The proportions of resident participation increased for case reports (20.8% vs 66.7%, p < 0.0001) and clinical research (17.0% vs 38.6%, p = 0.012), but were similar for laboratory research and topical reviews. The mean activities per resident increased for published abstracts (0.15 ± 0.41 to 1.26 ± 1.41, p < 0.0001), manuscripts (0.75 ± 1.37 to 1.00 ± 1.40, p = 0.36), and book chapters (0.02 ± 0.14 to 0.18 ± 0.60, p = 0.07). Rates of resident participation as first authors increased from 30.2% to 71.9% (p < 0.0001). The number of individual faculty mentors increased from 36 (preprogram) to 44 (postprogram). CONCLUSIONS: Our multifaceted program, designed to enhance resident and faculty engagement in scholarship, was associated with increased academic output and an expanded mentorship pool. The program was particularly effective at encouraging presentations at scientific meetings. Longitudinal analysis will determine whether such a program portfolio inspires an increase in academic careers involving neuroscience-oriented research.

Postnatal and adult consequences of loss of huntingtin during development: Implications for Huntington's disease.

The mutation in huntingtin (mHtt) leads to a spectrum of impairments in the developing forebrain of Huntington's disease (HD) mouse models. Whether these developmental alterations are due to loss- or gain-of-function mechanisms and contribute to HD pathogenesis is unknown. We examined the role of selective loss of huntingtin (Htt) function during development on postnatal vulnerability to cell death. We employed mice expressing very low levels of Htt throughout embryonic life to postnatal day 21 (Hdhd•hyp). We demonstrated that Hdhd•hyp mice exhibit: (1) late-life striatal and cortical neuronal degeneration; (2) neurological and skeletal muscle alterations; and (3) white matter tract impairments and axonal degeneration. Hdhd•hyp embryos also exhibited subpallial heterotopias, aberrant striatal maturation and deregulation of gliogenesis. These results indicate that developmental deficits associated with Htt functions render cells present at discrete neural foci increasingly susceptible to cell death, thus implying the potential existence of a loss-of-function developmental component to HD pathogenesis.

Selective expression of mutant huntingtin during development recapitulates characteristic features of Huntington's disease.

Recent studies have identified impairments in neural induction and in striatal and cortical neurogenesis in Huntington's disease (HD) knock-in mouse models and associated embryonic stem cell lines. However, the potential role of these developmental alterations for HD pathogenesis and progression is currently unknown. To address this issue, we used BACHD:CAG-Cre(ERT2) mice, which carry mutant huntingtin (mHtt) modified to harbor a floxed exon 1 containing the pathogenic polyglutamine expansion (Q97). Upon tamoxifen administration at postnatal day 21, the floxed mHtt-exon1 was removed and mHtt expression was terminated (Q97(CRE)). These conditional mice displayed similar profiles of impairments to those mice expressing mHtt throughout life: (i) striatal neurodegeneration, (ii) early vulnerability to NMDA-mediated excitotoxicity, (iii) impairments in motor coordination, (iv) temporally distinct abnormalities in striatal electrophysiological activity, and (v) altered corticostriatal functional connectivity and plasticity. These findings strongly suggest that developmental aberrations may play important roles in HD pathogenesis and progression.

Emerging Roles for CSF-1 Receptor and its Ligands in the Nervous System.

The colony-stimulating factor-1 receptor (CSF-1R) kinase regulates tissue macrophage homeostasis, osteoclastogenesis, and Paneth cell development. However, recent studies in mice have revealed that CSF-1R signaling directly controls the development and maintenance of microglia, and cell autonomously regulates neuronal differentiation and survival. While the CSF-1R-cognate ligands, CSF-1 and interleukin-34 (IL-34) compete for binding to the CSF-1R, they are expressed in a largely non-overlapping manner by mature neurons. The recent identification of a dominantly inherited, adult-onset, progressive dementia associated with inactivating mutations in the CSF-1R highlights the importance of CSF-1R signaling in the brain. We review the roles of the CSF-1R and its ligands in microglial and neural development and function, and their relevance to our understanding of neurodegenerative disease.