SARS-CoV-2 is associated with changes in brain structure in UK Biobank

Macro- and Microstructural White Matter Differences in Neurologic Postacute Sequelae of SARS-CoV-2 Infection

BACKGROUND AND PURPOSE

Neuropsychiatric complications of SARS-CoV-2 infection, also known as neurologic postacute sequelae of SARS-CoV-2 infection (NeuroPASC), affect 10%-60% of infected individuals. There is growing evidence that NeuroPASC is a multi system immune dysregulation disease affecting the brain. The behavioral manifestations of NeuroPASC, such as impaired processing speed, executive function, memory retrieval, and sustained attention, suggest widespread WM involvement. Although previous work has documented WM damage following acute SARS-CoV-2 infection, its involvement in NeuroPASC is less clear. We hypothesized that macrostructural and microstructural WM differences in NeuroPASC participants would accompany cognitive and immune system differences.

MATERIALS AND METHODS

In a cross-sectional study, we screened a total of 159 potential participants and enrolled 72 participants, with 41 asymptomatic controls (NoCOVID) and 31 NeuroPASC participants matched for age, sex, and education. Exclusion criteria included neurologic disorders unrelated to SARS-CoV-2 infection. Assessments included clinical symptom questionnaires, psychometric tests, brain MRI measures, and peripheral cytokine levels. Statistical modeling included separate multivariable regression analyses of GM/WM/CSF volume, WM microstructure, cognitive, and cytokine concentration between-group differences.

RESULTS

NeuroPASC participants had larger cerebral WM volume than NoCOVID controls (β = 0.229; 95% CI: 0.017-0.441; t = 2.16; P = .035). The most pronounced effects were in the prefrontal and anterior temporal WM. NeuroPASC participants also exhibited higher WM mean kurtosis, consistent with ongoing neuroinflammation. NeuroPASC participants had more self-reported symptoms, including headache, and lower performance on measures of attention, concentration, verbal learning, and processing speed. A multivariate profile analysis of the cytokine panel showed different group cytokine profiles (Wald-type-statistic = 44.6, P = .046), with interferon (IFN)-λ1 and IFN-λ2/3 levels higher in the NeuroPASC group.

CONCLUSIONS

NeuroPASC participants reported symptoms of lower concentration, higher fatigue, and impaired cognition compatible with WM syndrome. Psychometric testing confirmed these findings. NeuroPASC participants exhibited larger cerebral WM volume and higher WM mean kurtosis than NoCOVID controls. These findings suggest that immune dysregulation could influence WM properties to produce WM volume increases and consequent cognitive effects and headaches. Further work will be needed to establish mechanistic links among these variables.

Structural MRI correlates of cognitive and neuropsychiatric symptoms in Long COVID: a pilot study

Approximately 7% of COVID-19 patients (1.3% children) have exhibited symptoms of post-acute sequelae of SARS-CoV-2 infection (PASC), or Long COVID, and 20% of those present with neuropsychiatric symptoms. While a large number of MRI-based neuroimaging studies in this population have shown cortical atrophy in terms of gray matter volume and cortical thickness in patients, there is a growing body of work showing brain volume enlargements or thickness increases in patients compared to COVID negative controls. To investigate this further, we used structural magnetic resonance imaging (MRI) to examine differences in gray matter thickness for the cortical limbic and the dorsolateral prefrontal cortical regions between patients with Long COVID and healthy controls. Results showed increased cortical thickness in the caudal anterior, isthmus, and the posterior cingulate gyrus as well as the rostral middle frontal gyrus respectively along with higher gray matter volume in the posterior cingulate and the isthmus cingulate in patients with Long COVID. Cortical thickness and gray matter volumes for regions of interest (ROIs) were also associated with the severity measures, clinical dementia rating, and anxiety scores in the Long COVID group. Our findings provide supporting evidence for cortical hypertrophy in Long COVID.

Post-COVID breathlessness: a mathematical model of respiratory processing in the brain

Breathlessness is among the most common post-COVID symptoms. In a considerable number of patients, severe breathlessness cannot be explained by peripheral organ impairment. Recent concepts have described how such persistent breathlessness could arise from dysfunctional processing of respiratory information in the brain. In this paper, we present a first quantitative and testable mathematical model of how processing of respiratory-related signals could lead to breathlessness perception. The model is based on recent theories that the brain holds an adaptive and dynamic internal representation of a respiratory state that is based on previous experiences and comprises gas exchange between environment, lung and tissue cells. Perceived breathlessness reflects the brain's estimate of this respiratory state signaling a potentially hazardous disequilibrium in gas exchange. The internal respiratory state evolves from the respiratory state of the last breath, is updated by a sensory measurement of CO2 concentration, and is dependent on the current activity context. To evaluate our model and thus test the assumed mechanism, we used data from an ongoing rebreathing experiment investigating breathlessness in patients with post-COVID without peripheral organ dysfunction (N = 5) and healthy control participants without complaints after COVID-19 (N = 5). Although the observed breathlessness patterns varied extensively between individual participants in the rebreathing experiment, our model shows good performance in replicating these individual, heterogeneous time courses. The model assumes the same underlying processes in the central nervous system in all individuals, i.e., also between patients and healthy control participants, and we hypothesize that differences in breathlessness are explained by different weighting and thus influence of these processes on the final percept. Our model could thus be applied in future studies to provide insight into where in the processing cascade of respiratory signals a deficit is located that leads to (post-COVID) breathlessness. A potential clinical application could be, e.g., the monitoring of effects of pulmonary rehabilitation on respiratory processing in the brain to improve the therapeutic strategies.

A digital intervention for cognitive deficits following COVID-19: a randomized clinical trial

Post-COVID-19 cognitive deficits are common, persistent, and disabling. Evidence on effective treatments is limited. The goal of this study was to investigate the efficacy of a digital intervention to reduce cognitive and functional deficits in adults with persistent post-COVID-19 cognitive dysfunction. We used the remotely-delivered intervention in a randomized clinical trial conducted from July 13, 2021 to April 26, 2023. We hypothesized that participants in the intervention group would improve in measures of cognition and daily functioning. Participants were adults with cognitive deficits persisting >4 weeks following acute COVID-19 illness. Of 183 participants screened, 110 were enrolled; 98 participants (78.6% female; mean age = 48.1) completed at least one study visit. Participants were randomized 1:1 to the intervention (AKL-T01) or waitlist control. AKL-T01 is a digital therapeutic using a videogame interface to target attention and executive control. The intervention was delivered remotely for 6 weeks. The primary outcome was change in performance on a sustained attention measure (Digit Symbol Matching Task). The difference in the primary outcome between the intervention (n = 49) and controls (n = 49) was not statistically significant (F [3,261] = 0.12, p = 0.95). Secondary cognitive outcomes of task-switching (F[3,262] = 2.78, p = 0.04) and processing speed (F[3,267] = 4.57, p = 0.004) improved in the intervention relative to control. Secondary measures of functioning also improved in the intervention relative to control, including disability (F[1,82] = 4.02, p = 0.05) and quality of life (F[3,271] = 2.66, p = 0.05). Exploratory analyses showed a greater reduction in total fatigue (F[1,85] = 4.51, p = 0.04), cognitive fatigue (F[1,85] = 7.20, p = 0.009), and anxiety (F[1,87] = 7.42, p = 0.008) in the intervention relative to control. Despite the lack of improvement in sustained attention, select post-COVID-19 cognitive deficits may be ameliorated by targeted cognitive training with AKL-T01, with associated improvements in quality of life and fatigue. If replicated, the scalable nature of this digital intervention may help address substantial need for accessible, effective treatments among individuals with long COVID.

Effects of cognitive training and group psychotherapy on cognitive performance of post COVID-19 patients: an exploratory and non-randomized clinical trial

Cognitive complaints are common signs of the Post COVID-19 (PC) condition, but the extent and type of cognitive impairment may be heterogeneous. Little is known about neuropsychological treatment options. Preliminary evidence suggests cognitive symptoms may improve with cognitive training and naturally over time. In this clinical trial, we examined whether participation in a weekly group consisting of cognitive training and group psychotherapy is feasible and would exert beneficial effects on cognitive performance in PC and whether improvements were associated with intervention group participation or represented a temporal improvement effect during syndrome progression. 15 PC patients underwent an 8-week intervention. Cognitive performance was assessed before and after each intervention group participation. A control group of 15 PC patients with subjective neurocognitive or psychiatric complaints underwent two cognitive assessments with comparable time intervals without group participation. To attribute changes to the intervention group participation, interaction effects of group participation and time were checked for significance. This is an exploratory, non-randomized, non-blinded controlled clinical trial. Within the intervention group, significant improvements were found for most cognitive measures. However, significant time x group interactions were only detected in some dimensions of verbal memory and visuo-spatial construction skills. Significant time effects were observed for attention, concentration, memory, executive functions, and processing speed. The intervention setting was feasible and rated as helpful and relevant by the patients. Our results suggest that cognitive symptoms of PC patients may improve over time. Patients affected by both neurocognitive impairments and mental disorders benefit from group psychotherapy and neurocognitive training. The present study provides evidence for a better understanding of the dynamic symptomatology of PC and might help to develop further studies addressing possible therapy designs. The main limitations of this exploratory feasibility trial are the small sample size as well as the non-randomized design due to the clinical setting.

Characterization of cognitive symptoms in post COVID-19 patients

Cognitive symptoms (CS) belong to the most common manifestations of the Post COVID-19 (PC) condition. We sought to objectify CS in PC patients using routine diagnostic assessments: neurocognitive testing (NCT) and brain imaging (BI). Further, we investigated possible associations of CS with patient reported outcomes (PROs), and risk factors for developing CS. Clinical data and PROs of 315 PC patients were assessed at a mean of 6 months after SARS-CoV-2 infection. 231 (73.3%) patients reported any sort of CS. Among them, 78 underwent NCT and 55 received BI. In NCT, the cognitive domains most affected were the working memory, attention, and concentration. Nonetheless, pathological thresholds were exceeded only in few cases. Neurocognitive performance did not differ significantly between patients complaining of severe (n = 26) versus non-severe (n = 52) CS. BI findings were abnormal in 8 (14.5%) cases with CS but were most likely not related to PC. Patients reporting high severity of CS scored worse in the PHQ-9, FSS, WHOQOL-BREF, were more likely to report impaired sleep, and had a higher prevalence of psychiatric diagnoses. Overall, NCT could confirm mild impairment in some but not all PC patients with CS, while BI studies were abnormal in only few cases. CS severity did not affect NCT results, but severe CS were associated with symptoms of depression (PHQ-9), fatigue (FSS), reduced quality of life (WHOQOL-BREF) and higher prevalence of psychiatric illnesses. These findings support the importance of NCT, BI, and neuro-psychological assessment in the work-up of PC patients reporting CS. TRIAL REGISTRATION: Trial registration number and date of registration: DRKS00030974, 22 Dec 2022, retrospectively registered.

Functional brain alterations in COVID-19 patients using resting-state fMRI: a systematic review

This study systematically reviews the available evidence on resting-state functional magnetic resonance imaging (rs-fMRI) related to neurological symptoms and cognitive declines in COVID-19 patients. We followed PRISMA guidelines and looked up the PubMed, and Scopus databases for articles search on COVID-19 patients with neurological impairments, and functional connectivity alteration using rs-fMRI technique. Articles published between January 1, 2020, and May 31, 2024, are included in this study. The Quality Assessment Tool for Observational Prospective and Cross-Sectional Studies from the National Heart, Lung, and Blood Institute (NHLBI) was used to assess the quality of papers. A total of 15 articles met the inclusion criteria. The result reveals that the most prevalent neurological impairment associated with COVID-19 was cognitive decline, encompassing issues in attention, memory, processing speed, executive functions, language, and visuospatial ability. The brain connectivity results reveal that two brain areas were functionally altered; the prefrontal cortex and parahippocampus. The functional connectivity mainly increased in the frontal, temporal, and anterior piriform cortex, and reduced in the cerebellum, superior orbitofrontal cortex, and middle temporal gyrus, which also correlated with cognitive decline. The findings of neurological symptoms indicate one study reported a Disorder of Consciousness (DoC), and four studies reported COVID-19 patients with olfactory dysfunction. The present study concludes that COVID-19 can alter brain functional connectivity and offers significant insight into how COVID-19 affects the neuronal foundation of cognitive decline and other neurological impairments.

Rehabilitative interventions in patients with persistent post COVID-19 symptoms-a review of recent advances and future perspectives

The SARS-CoV-2 pandemic has not only caused millions of deaths but left also millions of people with persistent symptoms behind. These long-term COVID-19 sequelae cause a considerable burden on individuals´ health, healthcare systems, and economies worldwide given the high rate of SARS-CoV-2 infections. Therefore, rehabilitative interventions and strategies are needed to counteract the post COVID-19 sequelae. The importance of rehabilitation for patients with persistent COVID-19 symptoms has been recently also highlighted in a Call for Action by the World Health Organisation. Based on previously published research, but also in line with clinical experience, COVID-19 is not one specific disease but rather presents in different phenotypes that vary in their pathophysiological mechanisms, symptomatic manifestations, and potential interventional approaches. This review provides a proposal for differentiating post COVID-19 patients in non-organ-specific phenotypes that may help clinicians to evaluate patients and to plan therapeutic options. Furthermore, we present current unmet needs and suggest a potential pathway for a specific rehabilitation approach in people with persistent post-COVID symptoms.

Long-term follow-up of brain regional changes and the association with cognitive impairment in quarantined COVID-19 survivors

OBJECTIVE

This study aimed to evaluate the neuropsychiatric symptoms of quarantined COVID-19 survivors 15 months after discharge and explore its potential association with structural and functional brain changes and inflammation.

METHODS

A total of 51 quarantined COVID-19 survivors and 74 healthy controls were included in this study. Cognitive function was assessed using the THINC-integrated tool. Structural brain changes were examined through both surface- and volume-based analyses, and functional changes were assessed using resting-state amplitude low-frequency fluctuation (ALFF). Serum inflammatory markers were measured by a multiplexed flow cytometric assay.

RESULTS

COVID-19 survivors exhibited subjective cognitive decline compared to healthy controls, despite no significant differences in objective cognitive tasks. Structural analysis revealed significantly increased gray matter volume and cortical surface area in the left transverse temporal gyrus (Heschl's gyrus) in quarantined COVID-19 survivors. This enlargement was negatively correlated with cognitive impairment. The ALFF analysis showed decreased neural activity in multiple brain regions. Elevated levels of serum inflammatory markers were also found in COVID-19 survivors, including MIP-1a, MIP-1b, TNF-a, and IL-8, which correlated with functional abnormalities.

CONCLUSIONS

Our findings indicate a subjective cognitive decline in quarantined COVID-19 survivors 15 months after discharge, which is associated with brain structural alterations in the left Heschl's gyrus. The observed elevation of inflammatory markers suggests a potential mechanism involving inflammation-induced neurogenesis. These results contribute to our understanding of the possible mechanisms underlying long-term neuropsychiatric consequences of COVID-19 and highlight the need for further research to develop targeted interventions.

Resting-state functional connectome predicts sleep quality two months after the first negative COVID-19 antigen test

BACKGROUND

The COVID-19 pandemic has led to long-term neurological and psychological effects, including sleep disturbances. While prior studies have identified altered brain function post-COVID-19, specific functional connectivity (FC) patterns predicting sleep quality after recovery remain unclear. This study aims to identify FC patterns associated with sleep quality two months after the first negative COVID-19 antigen test.

METHODS

Using a connectome-based predictive modeling (CPM) approach, we identified the functional connectome regulating sleep quality based on a 164-region parcellation. Significant connections were analyzed using mediation models to examine their role in the relationship between anxiety, depression, and sleep.

RESULTS

FC between the right cerebellar peduncle and the left VIII of the cerebellum, and between the left middle temporal pole (MTP) and left ventral tegmental area (VTA), significantly predicted Pittsburgh Sleep Quality Index (PSQI) scores for sleep disturbances two months post-recovery (q2 = 0.059, MSE = 0.154, p = 0.017, r = 0.350). Mediation analysis showed a significant indirect effect of FC between the left MTP and VTA on the relationship between generalized anxiety and sleep disturbances (indirect effect = 0.013, 95% CI = [0.002, 0.03], pfdr <0.05). FC between the right dorsal raphe nucleus and ipsilateral regions-including occipital, parietal, and temporal areas-predicted PSQI scores for daytime dysfunction (q2 = 0.092, MSE = 0.678, p = 0.025, r = 0.342).

CONCLUSION

Post-COVID-19 brain connectivity and anxiety predict sleep quality. These findings highlight the potential for targeted therapeutic strategies to improve sleep and identify patients at risk for prolonged disturbances through FC biomarkers.

Temporal trajectories of long-COVID symptoms in adults with 22 months follow-up in a prospective cohort study in Norway

OBJECTIVES

There is a lack of large studies on long-COVID symptoms with symptoms measurements before the onset of COVID-19. Therefore, long-COVID is still poorly defined.

METHODS

The Norwegian COVID-19 Cohort Study is a population-based, open cohort of adult participants (aged 18-96 years) from Norway. From March 27, 2020, participants were recruited through social media, invitations, and nationwide media coverage. Fourteen somatic and cognitive symptoms were assessed at baseline and four follow-ups for up to 22 months. SARS-CoV-2 test status was obtained from a mandatory national registry or from self-report.

RESULTS

After follow-up, 15 737 participants had a SARS-CoV-2-positive test, 67 305 had a negative test, and 37 563 were still untested. Persistent symptoms reported more frequently by positive compared with negative participants one month after infection, were memory problems (3-6 months: adjusted odds ratio (aOR) = 6.8, CI = 5.7-8.1; >18 months: aOR = 9.4, CI = 4.1-22), and concentration problems (3-6 months: aOR = 4.1, CI = 3.5-4.7; >18 months: aOR = 4.4, CI = 2.0-9.7) as well fatigue, dyspnea, anosmia and dysgeusia.

CONCLUSIONS

COVID-19 was associated with cognitive symptoms, anosmia, dysgeusia, dyspnea, and fatigue as well as worsening of overall health up to 22 months after a SARS-CoV-2 test, even when correcting for symptoms before the onset of COVID-19.

Conceptual foundations of acetylcarnitine supplementation in neuropsychiatric long COVID syndrome: a narrative review

Post-acute sequelae of COVID-19 can present as multi-organ pathology, with neuropsychiatric symptoms being the most common symptom complex, characterizing long COVID as a syndrome with a significant disease burden for affected individuals. Several typical symptoms of long COVID, such as fatigue, depressive symptoms and cognitive impairment, are also key features of other psychiatric disorders such as myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and major depressive disorder (MDD). However, clinically successful treatment strategies are still lacking and are often inspired by treatment options for diseases with similar clinical presentations, such as ME/CFS. Acetylcarnitine, the shortest metabolite of a class of fatty acid metabolites called acylcarnitines and one of the most abundant blood metabolites in humans can be used as a dietary/nutritional supplement with proven clinical efficacy in the treatment of MDD, ME/CFS and other neuropsychiatric disorders. Basic research in recent decades has established acylcarnitines in general, and acetylcarnitine in particular, as important regulators and indicators of mitochondrial function and other physiological processes such as neuroinflammation and energy production pathways. In this review, we will compare the clinical basis of neuropsychiatric long COVID with other fatigue-associated diseases. We will also review common molecular disease mechanisms associated with altered acetylcarnitine metabolism and the potential of acetylcarnitine to interfere with these as a therapeutic agent. Finally, we will review the current evidence for acetylcarnitine as a supplement in the treatment of fatigue-associated diseases and propose future research strategies to investigate the potential of acetylcarnitine as a treatment option for long COVID.

COVID-19, Anxiety, and Body Mass Index Increase Leptin Levels: a Cross-sectional Multicentric Study

Although many efforts have been made to understand the pathophysiological mechanisms of COVID-19, critical gaps remain to be explored. This study aimed to investigate potential alterations in adipokine levels (specifically adiponectin, leptin, and resistin) among individuals with COVID-19. Within this population, we further assessed the association between these markers with both, body mass index (BMI) and psychiatric symptoms. This cross-sectional study included an age- and sex-matched sample of adults with COVID-19 (cases) and without COVID-19 (controls). We evaluated the severity of psychiatric symptoms, BMI, and adipokines. Individuals with COVID-19 presented greater BMI, stress levels, and leptin levels when compared to controls. Leptin levels were greater in individuals with moderate/severe COVID-19 as compared to individuals with COVID-19 who were asymptomatic or having mild symptoms. Leptin levels were positively correlated with BMI, severity of depressive and anxiety symptoms, and stress levels in the total sample. Leptin levels were also positively correlated with BMI, severity of anxiety symptoms, and stress levels in controls. In cases, there was a positive correlation between adiponectin and the severity of depressive symptoms and stress levels and leptin/resistin with BMI. A linear regression model revealed that BMI, severity of anxiety symptoms, and the diagnosis of COVID-19 are independently associated with increased leptin levels. Thus, leptin levels seem to be impacted by the COVID-19 infection, anxiety, and BMI.

Normative Neuroimaging Library: Designing a Comprehensive and Demographically Diverse Dataset of Healthy Controls to Support Traumatic Brain Injury Diagnostic and Therapeutic Development

The past decade has seen impressive advances in neuroimaging, moving from qualitative to quantitative outputs. Available techniques now allow for the inference of microscopic changes occurring in white and gray matter, along with alterations in physiology and function. These existing and emerging techniques hold the potential of providing unprecedented capabilities in achieving a diagnosis and predicting outcomes for traumatic brain injury (TBI) and a variety of other neurological diseases. To see this promise move from the research lab into clinical care, an understanding is needed of what normal data look like for all age ranges, sex, and other demographic and socioeconomic categories. Clinicians can only use the results of imaging scans to support their decision-making if they know how the results for their patient compare with a normative standard. This potential for utilizing magnetic resonance imaging (MRI) in TBI diagnosis motivated the American College of Radiology and Cohen Veterans Bioscience to create a reference database of healthy individuals with neuroimaging, demographic data, and characterization of psychological functioning and neurocognitive data that will serve as a normative resource for clinicians and researchers for development of diagnostics and therapeutics for TBI and other brain disorders. The goal of this article is to introduce the large, well-curated Normative Neuroimaging Library (NNL) to the research community. NNL consists of data collected from ∼1900 healthy participants. The highlights of NNL are (1) data are collected across a diverse population, including civilians, veterans, and active-duty service members with an age range (18-64 years) not well represented in existing datasets; (2) comprehensive structural and functional neuroimaging acquisition with state-of-the-art sequences (including structural, diffusion, and functional MRI; raw scanner data are preserved, allowing higher quality data to be derived in the future; standardized imaging acquisition protocols across sites reflect sequences and parameters often recommended for use with various neurological and psychiatric conditions, including TBI, post-traumatic stress disorder, stroke, neurodegenerative disorders, and neoplastic disease); and (3) the collection of comprehensive demographic details, medical history, and a broad structured clinical assessment, including cognition and psychological scales, relevant to multiple neurological conditions with functional sequelae. Thus, NNL provides a demographically diverse population of healthy individuals who can serve as a comparison group for brain injury study and clinical samples, providing a strong foundation for precision medicine. Use cases include the creation of imaging-derived phenotypes (IDPs), derivation of reference ranges of imaging measures, and use of IDPs as training samples for artificial intelligence-based biomarker development and for normative modeling to help identify injury-induced changes as outliers for precision diagnosis and targeted therapeutic development. On its release, NNL is poised to support the use of advanced imaging in clinician decision support tools, the validation of imaging biomarkers, and the investigation of brain-behavior anomalies, moving the field toward precision medicine.

Dexamethasone in COVID-19 treatment: Analyzing monotherapy and combination therapy approaches

The COVID-19 pandemic has prompted the exploration of effective treatment options, with dexamethasone emerging as a key corticosteroid for severe cases. This review evaluates the efficacy and safety of dexamethasone, highlighting its ability to reduce mortality rates, alleviate acute respiratory distress syndrome (ARDS), and mitigate hyperinflammation. While dexamethasone shows therapeutic promise, potential adverse effects-including cardiovascular issues, neuropsychiatric complications, lung infections, and liver damage-necessitate careful monitoring and individualized treatment strategies. The review also addresses the debate over using dexamethasone alone versus in combination with other therapies targeting SARS-CoV-2, examining potential synergistic effects and drug resistance. In summary, dexamethasone is a valuable treatment option for COVID-19 but its risks highlight the need for tailored surveillance approaches. Further research is essential to establish clear guidelines for optimizing treatment and improving patient outcomes.

Long COVID patients' brain activation is suppressed during walking and severer symptoms lead to stronger suppression

This research aims to study the factors contributing to Long COVID and its effects on motor and cognitive brain regions using population surveys and brain imaging. The goal is to provide new insights into the neurological effects of the illness and establish a basis for addressing neuropsychiatric symptoms associated with Long COVID. Study 1 used a cross-sectional design to collect data on demographic characteristics and factors related to Long COVID symptoms in 551 participants. In Study 2, subjects with Long COVID and SARS-CoV-2 uninfected individuals underwent fNIRS monitoring while performing various tasks. Study 1 found that gender, age, BMI, Days since the first SARS-CoV-2 infection, and Symptoms at first onset influenced Long COVID performance. Study 2 demonstrated that individuals in the SARS-CoV-2 uninfected group exhibited greater activation of cognitive function-related brain regions than those in the Long COVID group while performing a level walking task. Furthermore, individuals in the Long COVID group without functional impairment displayed higher activation of brain regions associated with motor function during a weight-bearing walking task than those with functional impairment. Among individuals with Long COVID, those with mild symptoms at onset exhibited increased activation of brain regions linked to motor and cognitive function relative to those with moderate symptoms at onset. Individuals with Long COVID exhibited decreased activation in brain regions associated with cognitive and motor function compared to SARS-CoV-2 uninfected individuals. Moreover, those with more severe initial symptoms or functional impairment displayed heightened inhibition in these brain regions.

Rapidly progressive brain atrophy in ventilated patients: a retrospective descriptive study

The relationship between mechanical ventilation-induced brain volume changes and ICU-acquired weakness (ICU-AW) is not clear. We assessed brain volume change in ventilated patients and identified associations with changes in extremity muscle strength. Patients admitted to the ICU due to the need for ventilation, and who underwent at least two head CT scans during hospitalization, were included. We employed an automated segmentation method to measure brain volume, recording changes in volume from baseline. Cases with brain volume reduction > 0% were assigned to the "brain atrophy group" and those with ≤ 0% reduction to the "preserved brain volume group." Medical Research Council (MRC) scores as an indicator of ICU-AW at discharge were compared between groups. There were 84 eligible patients, 71 in the brain atrophy group and 13 in the preserved brain volume group. Analysis of the brain atrophy group showed a significant brain volume reduction of - 3.3% over a median of 30 days. The median MRC scores were significantly lower in the brain atrophy group than in the preserved brain volume group (36 vs. 48, difference [95% CI]: - 12 [- 19.5- - 7.1]). Many ICU patients on mechanical ventilation showed rapidly progressive brain atrophy, and most of these patients developed ICU-AW.

Neurological Sequelae of Post-COVID-19 Fatigue: A Narrative Review of Dipeptidyl Peptidase IV-Mediated Cerebrovascular Complications

Coronavirus disease 2019 (COVID-19) has been a global pandemic affecting millions of people's lives, which has led to 'post-COVID-19 fatigue'. Alarmingly, severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) not only infects the lungs but also influences the heart and brain. Endothelial cell dysfunction and hypercoagulation, which we know occur with this infection, lead to thrombo-inflammation that can manifest as many myriad cardio-cerebrovascular disorders, such as brain fog, fatigue, cognitive dysfunction, etc. Additionally, SARS-CoV-2 has been associated with oxidative stress, protein aggregation, cytokine storm, and mitochondrial dysfunction in neurodegenerative diseases. Accordingly, the identification of molecular targets involved in these actions could provide strategies for preventing and treating this disease. In particular, the very common enzyme dipeptidyl peptidase IV (DPPIV) has recently been identified as a candidate co-receptor for the cell entry of the SARS-CoV-2 virus with its involvement in infection. In addition, DPPIV has been reported as a co-receptor for some viruses such as Middle East respiratory syndrome-coronavirus (MERS-CoV). It mediates immunologic reactions and diseases such as type 2 diabetes mellitus, obesity, and hypertension, which have been considered the prime risk factors for stroke among other types of cardio-cerebrovascular diseases. Unlike angiotensin-converting enzyme 2 (ACE2), DPPIV has been implicated in aggravating the course of infection due to its disruptive effect on inflammatory signaling networks and the neuro-glia-vascular unit. Regarding the neurological, physiological, and molecular grounds governing post-COVID-19 fatigue, this review focuses on DPPIV as one of such reasons that progressively establishes cerebrovascular grievances following SARS-CoV infection.

Influences of sex and gender on the associations between risk and protective factors, brain, and behavior

Risk and protective factors for psychiatric illnesses are linked to distinct structural and functional changes in the brain. Further, the prevalence of these factors varies across sexes and genders, yet the distinct and joint effects of sex and gender in this context have not been extensively characterized. This suggests that risk and protective factors may map onto the brain and uniquely influence individuals across sexes and genders. Here, we review how specific risk (childhood maltreatment, the COVID-19 pandemic, experiences of racism), and protective factors (social support and psychological resilience) distinctly influence the brain across sexes and genders. We also discuss the role of sex and gender in the compounding effects of risk factors and in the interdependent influences of risk and protective factors. As such, we call on researchers to consider sex and gender when researching risk and protective factors for psychiatric illnesses, and we provide concrete recommendations on how to account for them in future research. Considering protective factors alongside risk factors in research and acknowledging sex and gender differences will enable us to establish sex- and gender-specific brain-behavior relationships. This will subsequently inform the development of targeted prevention and intervention strategies for psychiatric illnesses, which have been lacking. To achieve sex and gender equality in mental health, acknowledging and researching potential differences will lead to a better understanding of men and women, males and females, and the factors that make them more vulnerable or resilient to psychopathology.

SARS-CoV-2 and HSV-1 Induce Amyloid Aggregation in Human CSF Resulting in Drastic Soluble Protein Depletion

The corona virus (SARS-CoV-2) pandemic and the resulting long-term neurological complications in patients, known as long COVID, have renewed interest in the correlation between viral infections and neurodegenerative brain disorders. While many viruses can reach the central nervous system (CNS) causing acute or chronic infections (such as herpes simplex virus 1, HSV-1), the lack of a clear mechanistic link between viruses and protein aggregation into amyloids, a characteristic of several neurodegenerative diseases, has rendered such a connection elusive. Recently, we showed that viruses can induce aggregation of purified amyloidogenic proteins via the direct physicochemical mechanism of heterogeneous nucleation (HEN). In the current study, we show that the incubation of HSV-1 and SARS-CoV-2 with human cerebrospinal fluid (CSF) leads to the amyloid aggregation of several proteins known to be involved in neurodegenerative diseases, such as APLP1 (amyloid β precursor like protein 1), ApoE, clusterin, α2-macroglobulin, PGK-1 (phosphoglycerate kinase 1), ceruloplasmin, nucleolin, 14-3-3, transthyretin, and vitronectin. Importantly, UV-inactivation of SARS-CoV-2 does not affect its ability to induce amyloid aggregation, as amyloid formation is dependent on viral surface catalysis via HEN and not its ability to replicate. Additionally, viral amyloid induction led to a dramatic drop in the soluble protein concentration in the CSF. Our results show that viruses can physically induce amyloid aggregation of proteins in human CSF and result in soluble protein depletion, thus providing a potential mechanism that may account for the association between persistent and latent/reactivating brain infections and neurodegenerative diseases.

Cognitive impact and brain structural changes in long COVID patients: a cross-sectional MRI study two years post infection in a cohort from Argentina

OBJECTIVE

Long COVID is a condition characterised by persistent symptoms after a SARS-CoV-2 infection, with neurological manifestations being particularly frequent. Existing research suggests that long COVID patients not only report cognitive symptoms but also exhibit measurable cognitive impairment. Neuroimaging studies have identified structural alterations in brain regions linked to cognitive functions. However, most of these studies have focused on patients within months of their initial infection. This study aims to explore the longer-term cognitive effects and brain structural changes in long COVID patients, approximately two years post-infection, in a cohort from San Martín, Buenos Aires, Argentina.

METHODS

We conducted a cross-sectional study involving 137 participants: 109 with long COVID symptoms and 28 healthy controls. The participants underwent an initial clinical assessment, completed a structured questionnaire and standardised scales, underwent a cognitive assessment, and had a brain MRI scan. Structural MRI images were processed via FreeSurfer and FSL to obtain volumetric measures for subcortical and cortical regions, along with regional cortical thickness. Differences between groups for these variables were analysed using ANCOVA, with permutation tests applied to correct for multiple comparisons.

RESULTS

Long COVID patients reported persistent cognitive symptoms such as memory problems and brain fog, with higher levels of fatigue and reduced quality of life compared to controls. Despite subjective cognitive complaints, cognitive tests did not reveal significant differences between groups, except for the TMT-A (p = 0.05). MRI analysis revealed decreased volume in the cerebellum (p = 0.03), lingual gyrus (p = 0.04), and inferior parietal regions (p = 0.03), and reduced cortical thickness in several areas, including the left and right postcentral gyri (p = 0.02, p = 0.03) and precuneus (p = 0.01, p = 0.02).

CONCLUSIONS

This study highlights the enduring impact of long COVID on quality of life and physical activity, with specific brain structural changes identified two years post-infection. Although cognitive tests did not show clear impairment, the observed brain atrophy and significant reduction in quality of life emphasize the need for comprehensive interventions and further longitudinal studies to understand the long-term effects of long COVID on cognition and brain health.

Human pluripotent stem cell-derived models of the hippocampus

The hippocampus is a crucial structure of the brain, recognised for its roles in the formation of memory, and our ability to navigate the world. Despite its importance, clear understanding of how the human hippocampus develops and its contribution to disease is limited due to the inaccessible nature of the human brain. In this regard, the advent of human pluripotent stem cell (hPSC) technologies has enabled the study of human biology in an unprecedented manner, through the ability to model development and disease as both 2D monolayers and 3D organoids. In this review, we explore the existing efforts to derive the hippocampal lineage from hPSCs and evaluate the various aspects of the in vivo hippocampus that are replicated in vitro. In addition, we highlight key diseases that have been modelled using hPSC-derived cultures and offer our perspective on future directions for this emerging field.

Constructing and exploring neuroimaging projects: a survey from clinical practice to scientific research

Over the past decades, numerous large-scale neuroimaging projects that involved the collection and release of multimodal data have been conducted globally. Distinguished initiatives such as the Human Connectome Project, UK Biobank, and Alzheimer's Disease Neuroimaging Initiative, among others, stand as remarkable international collaborations that have significantly advanced our understanding of the brain. With the advancement of big data technology, changes in healthcare models, and continuous development in biomedical research, various types of large-scale projects are being established and promoted worldwide. For project leaders, there is a need to refer to common principles in project construction and management. Users must also adhere strictly to rules and guidelines, ensuring data safety and privacy protection. Organizations must maintain data integrity, protect individual privacy, and foster stakeholders' trust. Regular updates to legislation and policies are necessary to keep pace with evolving technologies and emerging data-related challenges. CRITICAL RELEVANCE STATEMENT: By reviewing global large-scale neuroimaging projects, we have summarized the standards and norms for establishing and utilizing their data, and provided suggestions and opinions on some ethical issues, aiming to promote higher-quality neuroimaging data development. KEY POINTS: Global neuroimaging projects are increasingly advancing but still face challenges. Constructing and utilizing neuroimaging projects should follow set rules and guidelines. Effective data management and governance should be developed to support neuroimaging projects.

Brain structures as potential mediators of the causal effect of COVID 19 on migraine risk

Migraine is a common neurological disorder observed after coronavirus disease 2019 (COVID 19) infection. However, the intricate relationship between COVID 19 and migraine, particularly the potential mediating role of brain imaging-derived phenotypes (BIPs), remains unclear. This study used linkage disequilibrium score regression (LDSC), a bidirectional two-sample Mendelian randomization (MR) approach, and two-step MR analysis to investigate potential causal links. The robustness of the MR findings was corroborated through generalized summary-data-based Mendelian randomization (GSMR) and MR-Steiger methods. The results of the LDSC analysis revealed that the genetic correlation coefficient between COVID 19 traits and migraine was 0.0277 for infection (P = 0.0051), 0.1690 for hospitalization (P = 0.0016), and 0.1147 for severity (P = 0.0330). The genetic correlation coefficients between COVID 19 infection, hospitalization, severity and migraine and migraine with aura (MA) were 0.2654 (P = 0.0012), 0.2065 (P = 0.0043), and 0.1537 (P = 0.0230), respectively. Two-sample MR analysis revealed a significant causal association of COVID 19 infection (odds ratio [OR] 1.2502, P = 0.0083; OR 1.4956, P = 0.0084), hospitalization (OR 1.0689, P = 0.0138; OR 1.0919, P = 0.0208), and severity (OR 1.0644, P = 0.0072; OR 1.0844, P = 0.0098) with increased risk of migraine and migraine with aura (MA). Cortical thickness (CT), total surface area (TSA), and fractional anisotropy (FA) were identified as BIP intermediaries in the risk trajectory from COVID 19 to migraine. The TSA exhibited a more pronounced mediating effect than did CT. This study revealed that genetically predicted COVID 19 is associated with an increased risk of migraine and MA, and BIPs act as potential mediators of these causal relationships, offering insights into the neurobiological underpinnings of migraine in the context of COVID 19.

Translating insights into therapies for Long Covid

Long Covid is defined by a wide range of symptoms that persist after the acute phase of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. Commonly reported symptoms include fatigue, weakness, postexertional malaise, and cognitive dysfunction, with many other symptoms reported. Symptom range, duration, and severity are highly variable and partially overlap with symptoms of myalgic encephalomyelitis/chronic fatigue syndrome and other post-acute infectious syndromes, highlighting opportunities to define shared mechanisms of pathogenesis. Potential mechanisms of Long Covid are diverse, including persistence of viral reservoirs, dysregulated immune responses, direct viral damage of tissues targeted by SARS-CoV-2, inflammation driven by reactivation of latent viral infections, vascular endothelium activation or dysfunction, and subsequent thromboinflammation, autoimmunity, metabolic derangements, microglial activation, and microbiota dysbiosis. The heterogeneity of symptoms and baseline characteristics of people with Long Covid, as well as the varying states of immunity and therapies given at the time of acute infection, have made etiologies of Long Covid difficult to determine. Here, we examine progress on preclinical models for Long Covid and review progress being made in clinical trials, highlighting the need for large human studies and further development of models to better understand Long Covid. Such studies will inform clinical trials that will define treatments to benefit those living with this condition.

Nerve Growth Factor and Brain-Derived Neurotrophic Factor in COVID-19

Neurotrophins (NTs) constitute a family of small protein messengers that play a fundamental role in both the central and peripheral nervous systems. In particular, the nerve growth factor (NGF) and the brain-derived neurotrophic factor (BDNF) play a subtle role in the survival, differentiation, and functioning of neuronal populations, as well as in the fine regulation of immune functions. The SARS-CoV-2 infection was characterized by a sequela of symptoms (serious respiratory pathology, inflammatory storm, neurological discomfort, up to the less serious flu-like symptoms), which caused, at the end of 2023, more than 7 million deaths worldwide. Despite the official end of the pandemic, the physical and psychological consequences are currently the object of scientific research, both acute and chronic/long-lasting (Long-COVID-19). Given the multifactorial nature of the outcomes of SARS-CoV-2 infection in adults and children, several studies have investigated the potential involvement of the NGF and BDNF systems in the pathology. This narrative review aims to summarize the most recent evidence on this crucial topic.

[Mechanisms of prolonged symptoms following acute COVID-19: Some pathophysiological pathways]

INTRODUCTION

Following the Omicron wave in early 2022, an estimated 60-70% of the French population was infected with the SARS-CoV-2 virus. One out of ten infected subjects could have persistent symptoms three months after infection, representing a public health challenge.

CURRENT STATE OF KNOWLEDGE

The persistent symptoms may be secondary to diverse entities with distinct mechanisms. While organic infection sequelae occur mainly after severe COVID-19, some symptoms appear to be essentially psychological in origin; in addition, many subjects present stereotyped symptoms of fluctuating intensity with no identified anatomical or psychic substratum, often in the aftermath of a benign infection. The most frequent complaints are fatigue, pain, dyspnea and difficulty concentrating.

PERSPECTIVES

The hypotheses explored to explain these symptoms include: persistent immune dysfunction, inducted autoimmunity, and microbiome disturbances. Persistent viral antigens may lie at the crossroads of these mechanisms. To date, these different etiological avenues have yet to lead to the development of diagnostic tests or specific therapeutic strategies.

CONCLUSION

Prolonged symptoms after COVID-19 correspond to heterogeneous nosological entities with poorly understood mechanisms.

Current concepts in long COVID-19 brain fog and postural orthostatic tachycardia syndrome

Neurologic complications of long COVID-19 syndrome are one of the leading causes of global disability. In particular, post-COVID-19 cognitive dysfunction and dysautonomia in the form of postural orthostatic tachycardia syndrome (POTS) markedly affect patient quality of life and ability to return to work. The underlying pathophysiology of post-COVID-19 neurologic complications is unknown but is likely multifactorial with immune dysregulation and microvascular dysfunction playing central roles. Specific pathogenic factors with supportive evidence to date include cytokine-mediated inflammation, autoantibodies, immune exhaustion, disruption of the renin-angiotensin system, reduced serotonin levels, and microglial activation. The prevalence of post-COVID-19 cognitive dysfunction ranges from 10% to 88% and is affected by viral variant and hospitalization status among other factors, whereas that of long COVID-19 POTS is unknown due to referral bias and varying definitions. Treatment is largely supportive and often incorporates combined modalities. Marginal benefits with cognitive behavioral therapy, hyperbaric oxygen therapy, and supplements have been found for post-COVID-19 brain fog, whereas established POTS therapies aimed at improving venous return and reducing heart rate may reduce symptoms of long COVID-19 POTS. Although significant recovery has been noted for many cases of post-COVID-19 brain fog and POTS, prospective studies have revealed evidence of persistent symptoms and neurologic deficits a year after infection in some patients. Further studies that provide insight into the underlying pathophysiology of long COVID-19 are needed for development of target directed therapy.

Emerging signs of Alzheimer-like tau hyperphosphorylation and neuroinflammation in the brain post recovery from COVID-19

Coronavirus disease 2019 (COVID-19) has been suggested to increase the risk of memory decline and Alzheimer's disease (AD), the main cause of dementia in the elderly. However, direct evidence about whether COVID-19 induces AD-like neuropathological changes in the brain, especially post recovery from acute infection, is still lacking. Here, using postmortem human brain samples, we found abnormal accumulation of hyperphosphorylated tau protein in the hippocampus and medial entorhinal cortex within 4-13 months post clinically recovery from acute COVID-19, together with prolonged activation of glia cells and increases in inflammatory factors, even though no SARS-COV-2 invasion was detected in these regions. By contrast, COVID-19 did not change beta-amyloid deposition and hippocampal neuron number, and had limited effects on AD-related pathological phenotypes in olfactory circuits including olfactory bulb, anterior olfactory nucleus, olfactory tubercle, piriform cortex and lateral entorhinal cortex. These results provide neuropathological evidences linking COVID-19 with prognostic increase of risk for AD.

Cerebral small vessel injury in mice with damage to ACE2-expressing cerebral vascular endothelial cells and post COVID-19 patients

INTRODUCTION

The angiotensin-converting enzyme 2 (ACE2), which is expressed in cerebral vascular endothelial cells (CVECs), has been currently identified as a functional receptor for SARS-CoV-2.

METHODS

We specifically induced injury to ACE2-expressing CVECs in mice and evaluated the effects of such targeted damage through magnetic resonance imaging (MRI) and cognitive behavioral tests. In parallel, we recruited a single-center cohort of COVID-19 survivors and further assessed their brain microvascular injury based on cognition and emotional scales, cranial MRI scans, and blood proteomic measurements.

RESULTS

Here, we show an array of pathological and behavioral alterations characteristic of cerebral small vessel disease (CSVD) in mice that targeted damage to ACE2-expressing CVECs, and COVID-19 survivors. These CSVD-like manifestations persist for at least 7 months post-recovery from COVID-19.

DISCUSSION

Our findings suggest that SARS-CoV-2 may induce cerebral small vessel damage with persistent sequelae, underscoring the imperative for heightened clinical vigilance in mitigating or treating SARS-CoV-2-mediated cerebral endothelial injury throughout infection and convalescence.

HIGHLIGHTS

Cerebral small vessel disease-associated changes were observed after targeted damage to angiotensin-converting enzyme 2-expressing cerebral vascular endothelial cells. SARS-CoV-2 may induce cerebral small vessel damage with persistent sequelae. Clinical vigilance is needed in preventing SARS-CoV-2-induced cerebral endothelial damage during infection and recovery.

Brain-wide alterations revealed by spatial transcriptomics and proteomics in COVID-19 infection

Understanding the pathophysiology of neurological symptoms observed after severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) infection is essential to optimizing outcomes and therapeutics. To date, small sample sizes and narrow molecular profiling have limited the generalizability of findings. In this study, we profiled multiple cortical and subcortical regions in postmortem brains of patients with coronavirus disease 2019 (COVID-19) and controls with matched pulmonary pathology (total n = 42) using spatial transcriptomics, bulk gene expression and proteomics. We observed a multi-regional antiviral response without direct active SARS-CoV2 infection. We identified dysregulation of mitochondrial and synaptic pathways in deep-layer excitatory neurons and upregulation of neuroinflammation in glia, consistent across both mRNA and protein. Remarkably, these alterations overlapped substantially with changes in age-related neurodegenerative diseases, including Parkinson's disease and Alzheimer's disease. Our work, combining multiple experimental and analytical methods, demonstrates the brain-wide impact of severe acute/subacute COVID-19, involving both cortical and subcortical regions, shedding light on potential therapeutic targets within pathways typically associated with pathological aging and neurodegeneration.

Differences in brain structure and cognitive performance between patients with long-COVID and those with normal recovery

BACKGROUND

The pathophysiology of protracted symptoms after COVID-19 is unclear. This study aimed to determine if long-COVID is associated with differences in baseline characteristics, markers of white matter diffusivity in the brain, and lower scores on objective cognitive testing.

METHODS

Individuals who experienced COVID-19 symptoms for more than 60 days post-infection (long-COVID) (n = 56) were compared to individuals who recovered from COVID-19 within 60 days of infection (normal recovery) (n = 35). Information regarding physical and mental health, and COVID-19 illness was collected. The National Institute of Health Toolbox Cognition Battery was administered. Participants underwent magnetic resonance imaging (MRI) with diffusion tensor imaging (DTI). Tract-based spatial statistics were used to perform a whole-brain voxel-wise analysis on standard DTI metrics (fractional anisotropy, axial diffusivity, mean diffusivity, radial diffusivity), controlling for age and sex. NIH Toolbox Age-Adjusted Fluid Cognition Scores were used to compare long-COVID and normal recovery groups, covarying for Age-Adjusted Crystallized Cognition Scores and years of education. False discovery rate correction was applied for multiple comparisons.

RESULTS

There were no significant differences in age, sex, or history of neurovascular risk factors between the groups. The long-COVID group had significantly (p < 0.05) lower mean diffusivity than the normal recovery group across multiple white matter regions, including the internal capsule, anterior and superior corona radiata, corpus callosum, superior fronto-occiptal fasciculus, and posterior thalamic radiation. However, the effect sizes of these differences were small (all β<|0.3|) and no significant differences were found for the other DTI metrics. Fluid cognition composite scores did not differ significantly between the long-COVID and normal recovery groups (p > 0.05).

CONCLUSIONS

Differences in diffusivity between long-COVID and normal recovery groups were found on only one DTI metric. This could represent subtle areas of pathology such as gliosis or edema, but the small effect sizes and non-specific nature of the diffusion indices make pathological inference difficult. Although long-COVID patients reported many neuropsychiatric symptoms, significant differences in objective cognitive performance were not found.

Potential association between COVID-19 and neurological disorders: analysis of common genes and therapeutics

As the COVID-19 pandemic persists, the increasing evidences suggest that the patients with COVID-19 may face the risks of the neurological complications and sequelae. To address this issue, we conducted a comprehensive study aimed at exploring the relationship between COVID-19 and various neurological disorders, with a particular focus on the shared dysregulated genes and the potential therapeutic targets. We selected six neurological disorders for investigation, including Alzheimer's disease, epilepsy, stroke, Parkinson's disease, and the sleep disorders. Through the bioinformatics analysis of the association between these disorders and COVID-19, we aimed to uncover the common molecular mechanisms and the potential treatment pathways. In this study, we utilized the publicly available RNA-Seq and microarray datasets, and employed tools such as Limma and DESeq2 for the differential gene analysis. Through the Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis, we explored the common biological features and pathways. Additionally, we focused on analyzing the regulatory roles of miRNA and transcription factors on the shared differentially expressed genes, and predicted the potential drugs interacting with these genes. These analyses contribute to a better understanding of the relationship between COVID-19 and the neurological disorders, and provide a theoretical basis for the future treatment strategies. Through this research, we aim to offer the deeper insights to the scientific community and present the new perspectives for the clinical practice in addressing the challenges of the neurological complications and sequelae faced by the COVID-19 patients.

Exploring the effects of COVID-19 on verbal memory function in schizophrenia: Multiple case study and brief literature review

Individuals recovering from COVID-19 may experience persistent impairment in verbal memory performance, potentially due to illness-related hippocampal injury. Although verbal memory dysfunction is central to schizophrenia, the interactions between this vulnerability and COVID-19 remain unclear, with no imaging studies addressing the issue to-date. To explore this gap and generate hypotheses for future research, we adopted a multiple case study approach. Two pairs of individuals with an ICD-10 diagnosis of schizophrenia were selected, each consisting of one case with a positive COVID-19 anamnesis and one without. We calculated the Reliable Change Index to estimate the clinical significance of verbal memory performance changes, with annualized change rates in hippocampal volumes assessed against normative data. Compared to their matches, COVID-19 positive cases did not show mutually consistent changes in verbal memory performance: one case experienced a significant decline in verbal memory and learning, while the other showed a general normalization of test scores. Left hippocampal volumes showed a comparatively slowed increase, while the right hippocampi decreased in volume, although these atrophy rates did not exceed those expected in general population samples. Based on these findings, we hypothesize that COVID-19 alone does not lead to verbal memory decline in schizophrenia. Instead, the relationship between the diseases may depend on additional factors. Our case pairs differed in body mass index, systolic blood pressure, sex, phase of illness, and whole grey matter volume trajectories, leading us to hypothesize that these variables represent additional predictors or moderators of this relationship.

SARS-CoV-2 infection and the risk of depressive symptoms: a retrospective longitudinal study from the population-based CONSTANCES cohort

BACKGROUND

Should COVID-19 have a direct impact on the risk of depression, it would suggest specific pathways for prevention and treatment. In this retrospective population-based study, we aimed to examine the association of prior SARS-CoV-2 infection with depressive symptoms, distinguishing self-reported v. biologically confirmed COVID-19.

METHODS

32 007 participants from the SAPRIS survey nested in the French CONSTANCES cohort were included. COVID-19 was measured as followed: ad hoc serologic testing, self-reported PCR or serology positive test results, and self-reported COVID-19. Depressive symptoms were measured with the Center of Epidemiologic Studies-Depression Scale (CES-D). Outcomes were depressive symptoms (total CES-D score, its four dimensions, and clinically significant depressive symptoms) and exposure was prior COVID-19 (no COVID-19/self-reported unconfirmed COVID-19/biologically confirmed COVID-19).

RESULTS

In comparison to participants without COVID-19, participants with self-reported unconfirmed COVID-19 and biologically confirmed COVID-19 had higher CES-D scores (β for one interquartile range increase [95% CI]: 0.15 [0.08-0.22] and 0.09 [0.05-0.13], respectively) and somatic complaints dimension scores (0.15 [0.09-0.21] and 0.10 [0.07-0.13]). Only those with self-reported but unconfirmed COVID-19 had higher depressed affect dimension scores (0.08 [0.01-0.14]). Accounting for ad hoc serologic testing only, the CES-D score and the somatic complaints dimension were only associated with the combination of self-reported COVID-19 and negative serology test results.

CONCLUSIONS

The association between COVID-19 and depressive symptoms was merely driven by somatic symptoms of depression and did not follow a gradient consistent with the hypothesis of a direct impact of SARS-CoV-2 infection on the risk of depression.

Association between SARS-CoV-2 infection before the age of two and child development

BACKGROUND

To compare the differences in child development between children who contracted COVID-19 after February 1st, 2022, the period when the B.1.1.529 variant outbreak began to peak in Thailand, and those who did not.

METHODS

A prospective cohort study was conducted in an outpatient pediatric clinic at a tertiary hospital in southern Thailand. COVID-19 was diagnosed based on the results of an FDA-approved antigen test or RT-PCR using a swab sample collected from the nasopharynx, nose, or throat. Child development was assessed using the Ages and Stages Questionnaire, Third Edition (ASQ-3).

RESULTS

Of the 336 participants, 180 (53.6%) had a history of COVID-19. Almost all of them had mild COVID-19. The mean (SD) age at infection was 1.3 (0.3) years, and the median (IQR) duration between infection and ASQ-3 assessment was 193.5 (167.8, 216.2) days. The ASQ-3 scores at the ages of 18 (n = 166; 90 COVID-19 positive) and 24 months (n = 170; 90 COVID-19 positive) revealed no statistically significant differences between children with and without a history of COVID-19. Both groups had comparable proportions of developmental scores <1 SD below the mean.

CONCLUSIONS

Mild COVID-19 in young children did not increase the risk of developmental delays.

IMPACT

This cohort study was conducted during the Omicron pandemic. Of the 336 children, no clinical or statistically significant differences were observed in the scores of the Ages & Stages Questionnaire, Third Edition, at 18 or 24 months of age among the 180 participants with a history of mild SARS-CoV-2 infection, at an average of 6 months post-infection, and those without. The findings suggest that mild SARS-CoV-2 infection before the age of 2 years is not associated with developmental delays. Strategies to prevent severe SARS-CoV-2 infection in young children, especially COVID-19 immunization, need to be highlighted.

Inflammation and olfactory loss are associated with at least 139 medical conditions

Olfactory loss accompanies at least 139 neurological, somatic, and congenital/hereditary conditions. This observation leads to the question of whether these associations are correlations or whether they are ever causal. Temporal precedence and prospective predictive power suggest that olfactory loss is causally implicated in many medical conditions. The causal relationship between olfaction with memory dysfunction deserves particular attention because this sensory system has the only direct projection to memory centers. Mechanisms that may underlie the connections between medical conditions and olfactory loss include inflammation as well as neuroanatomical and environmental factors, and all 139 of the medical conditions listed here are also associated with inflammation. Olfactory enrichment shows efficacy for both prevention and treatment, potentially mediated by decreasing inflammation.

Brain and cognitive changes in patients with long COVID compared with infection-recovered control subjects

Between 2.5% and 28% of people infected with SARS-CoV-2 suffer long COVID or persistence of symptoms for months after acute illness. Many symptoms are neurological, but the brain changes underlying the neuropsychological impairments remain unclear. This study aimed to provide a detailed description of the cognitive profile, the pattern of brain alterations in long COVID and the potential association between them. To address these objectives, 83 patients with persistent neurological symptoms after COVID-19 were recruited, and 22 now healthy control subjects chosen because they had suffered COVID-19 but did not experience persistent neurological symptoms. Patients and controls were matched for age, sex and educational level. All participants were assessed by clinical interview, comprehensive standardized neuropsychological tests and structural MRI. The mean global cognitive function of patients with long COVID assessed by Addenbrooke's Cognitive Examination-III screening test [overall cognitive level (OCLz) = -0.39 ± 0.12] was significantly below the infection recovered-controls (OCLz = +0.32 ± 0.16, P < 0.01). We observed that 48% of patients with long COVID had episodic memory deficit, with 27% also with impaired overall cognitive function, especially attention, working memory, processing speed and verbal fluency. The MRI examination included grey matter morphometry and whole brain structural connectivity analysis. Compared to infection recovered controls, patients had thinner cortex in a specific cluster centred on the left posterior superior temporal gyrus. In addition, lower fractional anisotropy and higher radial diffusivity were observed in widespread areas of the patients' cerebral white matter relative to these controls. Correlations between cognitive status and brain abnormalities revealed a relationship between altered connectivity of white matter regions and impairments of episodic memory, overall cognitive function, attention and verbal fluency. This study shows that patients with neurological long COVID suffer brain changes, especially in several white matter areas, and these are associated with impairments of specific cognitive functions.

Mechanisms of long COVID and the path toward therapeutics

Long COVID, a type of post-acute sequelae of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (PASC) defined by medically unexplained symptoms following infection with SARS-CoV-2, is a newly recognized infection-associated chronic condition that causes disability in some people. Substantial progress has been made in defining its epidemiology, biology, and pathophysiology. However, there is no cure for the tens of millions of people believed to be experiencing long COVID, and industry engagement in developing therapeutics has been limited. Here, we review the current state of knowledge regarding the biology and pathophysiology of long COVID, focusing on how the proposed mechanisms explain the physiology of the syndrome and how they provide a rationale for the implementation of a broad experimental medicine and clinical trials agenda. Progress toward preventing and curing long COVID and other infection-associated chronic conditions will require deep and sustained investment by funders and industry.

COVID-19 related cognitive, structural and functional brain changes among Italian adolescents and young adults: a multimodal longitudinal case-control study

Coronavirus disease 2019 (COVID-19) has been associated with brain functional, structural, and cognitive changes that persist months after infection. Most studies of the neurologic outcomes related to COVID-19 focus on severe infection and aging populations. Here, we investigated the neural activities underlying COVID-19 related outcomes in a case-control study of mildly infected youth enrolled in a longitudinal study in Lombardy, Italy, a global hotspot of COVID-19. All participants (13 cases, 27 controls, mean age 24 years) completed resting-state functional (fMRI), structural MRI, cognitive assessments (CANTAB spatial working memory) at baseline (pre-COVID) and follow-up (post-COVID). Using graph theory eigenvector centrality (EC) and data-driven statistical methods, we examined differences in ECdelta (i.e., the difference in EC values pre- and post-COVID-19) and Volumetricdelta (i.e., the difference in cortical volume of cortical and subcortical areas pre- and post-COVID) between COVID-19 cases and controls. We found that ECdelta significantly between COVID-19 and healthy participants in five brain regions; right intracalcarine cortex, right lingual gyrus, left hippocampus, left amygdala, left frontal orbital cortex. The left hippocampus showed a significant decrease in Volumetricdelta between groups (p = 0.041). The reduced ECdelta in the left amygdala associated with COVID-19 status mediated the association between COVID-19 and disrupted spatial working memory. Our results show persistent structural, functional and cognitive brain changes in key brain areas associated with olfaction and cognition. These results may guide treatment efforts to assess the longevity, reversibility and impact of the observed brain and cognitive changes following COVID-19.

Cerebral Malformations Related to Coronavirus Disease 2019 during Pregnancy

The pandemic of severe-acute-respiratory-syndrome-related coronavirus (SARS-CoV-2) has shown a wide spectrum of possible consequences in children, ranging from asymptomatic patients to the development of severe conditions, such as multisystem inflammatory syndrome in children and encephalopathies related to cytokine storm. Specifically, neurological and neuroimaging abnormalities, ranging from mild-to-the severe ones, have been documented in children as well, such as postinfectious immune-mediated acute disseminated encephalomyelitis, myelitis, neural enhancement, cranial nerve enhancement, and cortical injury, also without neurological symptoms. Considering the neurotropism of coronaviruses and SARS-CoV-2, which has been well described in the literature, we reviewed the literature reporting possible cerebral malformation in neonates due to the infection of SARS-CoV-2 in pregnancy. Coronavirus disease 2019 (COVID-19) during pregnancy might develop cerebral disorders in several ways. Articles in English in the literature were screened using the following search terms: (1) “brain malformations” AND “COVID-19”; (2) “cerebral malformations” AND “COVID-19”; (3) brain malformations AND “Sars-Cov-2”; (4) “cerebral malformations “AND “Sars-Cov-2.” Considering the congenital brain malformation found in newborns exposed to infection of SARS-Cov-2 pre- or neonatally, we identified one paper which reported three neonates with cerebral malformation. Although sporadic, cerebral malformations like atypical signals in white matter with delayed myelination, brain dysplasia/hypoplasia with delayed myelination, and unusual signals in the periventricular regions have been documented.

Characteristics of the Structural Connectivity in Patients with Brain Injury and Chronic Health Symptoms: A Pilot Study

Diffusion properties from diffusion tensor imaging (DTI) are exquisitely sensitive to white matter abnormalities incurred during traumatic brain injury (TBI), especially for those patients with chronic post-TBI symptoms such as headaches, dizziness, fatigue, etc. The evaluation of structural and functional connectivity using DTI has become a promising method for identifying subtle alterations in brain connectivity associated with TBI that are otherwise not visible with conventional imaging. This study assessed whether TBI patients with (n = 17) or without (n = 16) chronic symptoms (TBIcs/TBIncs) exhibit any changes in structural connectivity (SC) and mean fractional anisotropy (mFA) of intra- and inter-hemispheric connections when compared to a control group (CG) (n = 13). Reductions in SC and mFA were observed for TBIcs compared to CG, but not for TBIncs. More connections were found to have mFA reductions than SC reductions. On the whole, SC is dominated by ipsilateral connections for all the groups after the comparison of contralateral and ipsilateral connections. More contra-ipsi reductions of mFA were found for TBIcs than TBIncs compared to CG. These findings suggest that TBI patients with chronic symptoms not only demonstrate decreased global and regional mFA but also reduced structural network connectivity.

Changes in memory and cognition during the SARS-CoV-2 human challenge study

Background

Patient-reported outcomes and cross-sectional evidence show an association between COVID-19 and persistent cognitive problems. The causal basis, longevity and domain specificity of this association is unclear due to population variability in baseline cognitive abilities, vulnerabilities, virus variants, vaccination status and treatment.

Methods

Thirty-four young, healthy, seronegative volunteers were inoculated with Wildtype SARS-CoV-2 under prospectively controlled conditions. Volunteers completed daily physiological measurements and computerised cognitive tasks during quarantine and follow-up at 30, 90, 180, 270, and 360 days. Linear modelling examined differences between 'infected' and 'inoculated but uninfected' individuals. The main cognitive endpoint was the baseline corrected global cognitive composite score across the battery of tasks administered to the volunteers. Exploratory cognitive endpoints included baseline corrected scores from individual tasks. The study was registered on ClinicalTrials.gov with the identifier NCT04865237 and took place between March 2021 and July 2022.

Findings

Eighteen volunteers developed infection by qPCR criteria of sustained viral load, one without symptoms and the remainder with mild illness. Infected volunteers showed statistically lower baseline-corrected global composite cognitive scores than uninfected volunteers, both acutely and during follow up (mean difference over all time points = -0.8631, 95% CI = -1.3613, -0.3766) with significant main effect of group in repeated measures ANOVA (F (1,34) = 7.58, p = 0.009). Sensitivity analysis replicated this cross-group difference after controlling for community upper respiratory tract infection, task-learning, remdesivir treatment, baseline reference and model structure. Memory and executive function tasks showed the largest between-group differences. No volunteers reported persistent subjective cognitive symptoms.

Interpretation

These results support larger cross sectional findings indicating that mild Wildtype SARS-CoV-2 infection can be followed by small changes in cognition and memory that persist for at least a year. The mechanistic basis and clinical implications of these small changes remain unclear.

Funding

This study was funded through the UK Vaccine Taskforce of the Department for Business, Energy and Industrial Strategy (BEIS) of Her Majesty's Government. WT was funded by the EPSRC through the CDT for Neurotechnology Imperial College London.

Enhancing diagnostic accuracy in symptom-based health checkers: a comprehensive machine learning approach with clinical vignettes and benchmarking

Introduction

The development of machine learning models for symptom-based health checkers is a rapidly evolving area with significant implications for healthcare. Accurate and efficient diagnostic tools can enhance patient outcomes and optimize healthcare resources. This study focuses on evaluating and optimizing machine learning models using a dataset of 10 diseases and 9,572 samples.

Methods

The dataset was divided into training and testing sets to facilitate model training and evaluation. The following models were selected and optimized: Decision Tree, Random Forest, Naive Bayes, Logistic Regression and K-Nearest Neighbors. Evaluation metrics included accuracy, F1 scores, and 10-fold cross-validation. ROC-AUC and precision-recall curves were also utilized to assess model performance, particularly in scenarios with imbalanced datasets. Clinical vignettes were employed to gauge the real-world applicability of the models.

Results

The performance of the models was evaluated using accuracy, F1 scores, and 10-fold cross-validation. The use of ROC-AUC curves revealed that model performance improved with increasing complexity. Precision-recall curves were particularly useful in evaluating model sensitivity in imbalanced dataset scenarios. Clinical vignettes demonstrated the robustness of the models in providing accurate diagnoses.

Discussion

The study underscores the importance of comprehensive model evaluation techniques. The use of clinical vignette testing and analysis of ROC-AUC and precision-recall curves are crucial in ensuring the reliability and sensitivity of symptom-based health checkers. These techniques provide a more nuanced understanding of model performance and highlight areas for further improvement.

Conclusion

This study highlights the significance of employing diverse evaluation metrics and methods to ensure the robustness and accuracy of machine learning models in symptom-based health checkers. The integration of clinical vignettes and the analysis of ROC-AUC and precision-recall curves are essential steps in developing reliable and sensitive diagnostic tools.

Post-COVID pandemic: The new normal and aftermath

Background

The COVID-19 pandemic has brought about unparalleled worldwide transformations, impacting all facets of human existence, including health systems, economies, societal norms, and individual behaviors.

Aim

The goal is to comprehend the enduring alterations in public health strategies, economic recuperation processes, changes in work and education paradigms, and the psychological consequences for populations globally.

Methods and Materials

This analysis uses a multidisciplinary approach by incorporating data from healthcare studies, economic reports, educational research, and psychological assessments. It aims to offer a comprehensive perspective on the world after the pandemic.

Results

The findings suggest that the "New Normal" encompasses a wide range of changes, such as a greater dependence on digital technology, a transition toward remote work and learning, substantial modifications in global supply chains, and a revised outlook on health and wellness. The potential long-term consequences of these changes indicate that some may provide opportunities for innovation and expansion, whereas others present challenges that necessitate strategic planning and policy interventions.

Conclusion

The aftermath of the COVID-19 pandemic presents a critical moment for global leaders, policymakers, and individuals to navigate the complexities of a transformed world, emphasizing the need for resilience, adaptability, and a renewed commitment to collective well-being.

Neuro-molecular perspectives on long COVID-19 impacted cerebrovascular diseases - a role for dipeptidyl peptidase IV

The coronavirus disease 2019 (COVID-19) has caused immense devastation globally with many outcomes that are now extending to its long-term sequel called long COVID. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infects not only lungs, but also the brain and heart in association with endothelial cell dysfunction, coagulation abnormalities, and thrombosis leading to cardio-cerebrovascular health issues. Fatigue, cognitive decline, and brain fog are common neurological symptoms in persisting long COVID. Neurodegenerative processes and SARS-CoV-2 infection manifest overlapping molecular mechanisms, such as cytokine dysregulation, inflammation, protein aggregation, mitochondrial dysfunction, and oxidative stress. Identifying the key molecules in these processes is of importance for prevention and treatment of this disease. In particular, Dipeptidyl peptidase IV (DPPIV), a multifunctional peptidase has recently drawn attention as a potential co-receptor for SARS-CoV-2 infection and cellular entry. DPPIV is a known co-receptor for some other COVID viruses including MERS-Co-V. DPPIV regulates the immune responses, obesity, glucose metabolism, diabetes, and hypertension that are associated with cerebrovascular manifestations including stroke. DPPIV likely worsens persisting COVID-19 by disrupting inflammatory signaling pathways and the neurovascular system. This review highlights the neurological, cellular and molecular processes concerning long COVID, and DPPIV as a potential key factor contributing to cerebrovascular dysfunctions following SARS-CoV-2 infection.

Insights into COVID-19 pathophysiology from a longitudinal multisystem report during acute infection

The Coronavirus disease 2019 (COVID-19), an illness caused by a SARS-CoV-2 viral infection, has been associated with neurological and neuropsychiatric disorders, revealing its impact beyond the respiratory system. Most related research involved individuals with post-acute or persistent symptoms of COVID-19, also referred to as long COVID or Post-Acute Sequelae of COVID-19 (PASC). In this longitudinal unique report, we aimed to describe the acute supraspinal and corticospinal changes and functional alterations induced by a COVID-19 infection using neuroimaging, neurophysiological and clinical assessment of a participant during acute infection, as compared to three other visits where the participant had no COVID-19. The results favor a multisystem impairment, impacting cortical activity, functional connectivity, and corticospinal excitability, as well as motor and cardiovascular function. The report suggests pathophysiological alteration and impairment already present at the acute stage, that if resolved tend to lead to a full clinical recovery. Such results could be also insightful into PASC symptomatology.