Heterogeneity in Regional Damage Detected by Neuroimaging and Neuropathological Studies in Older Adults With COVID-19: A Cognitive-Neuroscience Systematic Review to Inform the Long-Term Impact of the Virus on Neurocognitive Trajectories

Causal effect of COVID-19 on longitudinal volumetric changes in subcortical structures: A mendelian randomization study

A few observational neuroimaging investigations have reported subcortical structural changes in the individuals who recovered from the coronavirus disease-2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), but the causal relationships between COVID-19 and longitudinal changes of subcortical structures remain unclear. We performed two-sample Mendelian randomization (MR) analyses to estimate putative causal relationships between three COVID-19 phenotypes (susceptibility, hospitalization, and severity) and longitudinal volumetric changes of seven subcortical structures derived from MRI. Our findings demonstrated that genetic liability to SARS-CoV-2 infection had a great long-term impact on the volumetric reduction of subcortical structures, especially caudate. Our investigation may contribute in part to the understanding of the neural mechanisms underlying COVID-19-related neurological and neuropsychiatric sequelae.

Frontal-striatal glucose metabolism and fatigue in patients with multiple sclerosis, long COVID, and COVID-19 recovered controls

This study compared brain glucose metabolism using FDG-PET in the caudate nucleus, putamen, globus pallidus, thalamus, and dorsolateral prefrontal cortex (DLPFC) among patients with Long COVID, patients with fatigue, people with multiple sclerosis (PwMS) patients with fatigue, and COVID recovered controls. PwMS exhibited greater hypometabolism compared to long COVID patients with fatigue and the COVID recovered control group in all studied brain areas except the globus pallidus (effect size range 0.7-1.5). The results showed no significant differences in glucose metabolism between patients with Long COVID and the COVID recovered control group in these regions. These findings suggest that long COVID fatigue may involve non-CNS systems, neurotransmitter imbalances, or psychological factors not captured by FDG-PET, while MS-related fatigue is associated with more severe frontal-striatal circuit dysfunction due to demyelination and neurodegeneration. Symmetrical standardized uptake values (SUVs) between hemispheres in all groups imply that fatigue in these conditions may be related to global or network-level alterations rather than hemisphere-specific changes. Future studies should employ fine-grained analysis methods, explore other brain regions, and control for confounding factors to better understand the pathophysiology of fatigue in MS and long COVID. Longitudinal studies tracking brain glucose metabolism in patients with Long COVID could provide insights into the evolution of metabolic patterns as the condition progresses.

Resting-state neural dynamics changes in older adults with post-COVID syndrome and the modulatory effect of cognitive training and sex

Post-COVID syndrome manifests with numerous neurological and cognitive symptoms, the precise origins of which are still not fully understood. As females and older adults are more susceptible to developing this condition, our study aimed to investigate how post-COVID syndrome alters intrinsic brain dynamics in older adults and whether biological sex and cognitive training might modulate these effects, with a specific focus on older females. The participants, aged between 60 and 75 years, were divided into three experimental groups: healthy old female, post-COVID old female and post-COVID old male. They underwent an adaptive task-switching training protocol. We analysed multiscale entropy and spectral power density of resting-state EEG data collected before and after the training to assess neural signal complexity and oscillatory power, respectively. We found no difference between post-COVID females and males before training, indicating that post-COVID similarly affected both sexes. However, cognitive training was effective only in post-COVID females and not in males, by modulating local neural processing capacity. This improvement was further evidenced by comparing healthy and post-COVID females, wherein the latter group showed increased finer timescale entropy (1-30 ms) and higher frequency band power (11-40 Hz) before training, but these differences disappeared following cognitive training. Our results suggest that in older adults with post-COVID syndrome, there is a pronounced shift from more global to local neural processing, potentially contributing to accelerated neural aging in this condition. However, cognitive training seems to offer a promising intervention method for modulating these changes in brain dynamics, especially among females.

Quality of Sleep and Mental Symptoms Contribute to Health-Related Quality of Life after COVID-19 Pneumonia, a Follow-Up Study of More than 2 Years

A follow-up study was designed to assess correlations among physical signs, quality of sleep, common mental symptoms, and health-related quality of life after moderate to severe COVID-19 pneumonia. Daily changes in dyspnoea and pulse oximetry were recorded (200 days), and four evaluations (in >2 years) were performed on quality of sleep, mental symptoms, cognitive performance, and health-related quality of life. In a single center, 72 adults participated in the study (52.5 ± 13.7 years old), with no psychiatry/neurology/chronic lung/infectious diseases, chronic use of corticosteroids/immunosuppressive therapy, or pregnancy. Daily agendas showed delayed decreases in dyspnoea scores compared to pulse oximetry and heart rate recordings; however, changes in pulse oximetry were minimal. Slight changes in cognitive performance were related to the general characteristics of the participants (obesity and tobacco use) and with the severity of acute disease (MANCOVA, p < 0.001). Health-related quality of life gradually improved (MANCOVA, p < 0.004). During recovery, bad quality of sleep and mental symptoms (mainly attention/concentration) contributed to the subscores on health perception and vitality in the health-related quality of life assessment. Early mental support services including sleep hygiene could be beneficial during rehabilitation after acute COVID-19.

Persistent fatigue in post-acute COVID syndrome is associated with altered T1 MRI texture in subcortical structures: a preliminary investigation

Post-acute COVID syndrome (PACS) is a global health concern and is often associated with debilitating symptoms. Post-COVID fatigue is a particularly frequent and troubling issue, and its underlying mechanisms remain incompletely understood. One potential contributor is micropathological injury of subcortical and brainstem structures, as has been identified in other patient populations. Texture-based analysis (TA) may be used to measure such changes in anatomical MRI data. The present study develops a methodology of voxel-wise TA mapping in subcortical and brainstem regions, which is then applied to T1-weighted MRI data from a cohort of 48 individuals who had PACS (32 with and 16 without ongoing fatigue symptoms) and 15 controls who had cold and flu-like symptoms but tested negative for COVID-19. Both groups were assessed an average of 4-5 months post-infection. There were no significant differences between PACS and control groups, but significant differences were observed within the PACS groups, between those with and without fatigue symptoms. This included reduced texture energy and increased entropy, along with reduced texture correlation, cluster shade and profile in the putamen, pallidum, thalamus and brainstem. These findings provide new insights into the neurophysiological mechanisms that underlie PACS, with altered tissue texture as a potential biomarker of this debilitating condition.

Decision-making ability limitations and brain neural activity changes in healthcare workers after mild COVID-19

Studies have demonstrated that the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) extensively affects brain function. Although cognitive dysfunction is considered a common manifestation in COVID-19 patients during the recovery period, the potential changes in decision-making ability, are not yet clear. Decision-making functions are essential to the work of healthcare workers. However, there is a lack of a multidimensional assessment of its functioning in COVID-19 cases. Here, we used tests combined with the resting-state functional magnetic resonance imaging (rs-fMRI) stabilization feature amplitude of low-frequency fluctuations (ALFF) to explore decision-making behavior and brain neural activity changes in healthcare workers after mild COVID-19. Participants were divided into the SARS-CoV-2 infected group (SI, n = 41) and healthy controls (HC, n = 42). All participants underwent a series of neuropsychological tests. They performed the Iowa Gambling Task (IGT) and the Game of Dice Task (GDT), followed by fMRI (n = 20) to assess their decision-making ability under ambiguous and risky conditions and changes in brain neural activity. The SI group performed worse in verbal memory than the HC group. Furthermore, the SI group performed worse in the IGT, whereas no significant difference was observed in the GDT. In addition, rs-fMRI showed enhanced spontaneous neural activity in the postcentral gyrus and inferior parietal lobe in the SI group compared to the HC group.

Long COVID in Brain Health Research: A Call to Action

The COVID-19 pandemic has brought attention to the long-term consequences of the virus, particularly the persistent symptoms that characterize long COVID. This syndrome, which can last for months after the initial infection, includes a range of neurological and neuropsychiatric manifestations that have significant implications for brain health and dementia research. This review explores the current understanding of long COVID's cognitive, neurological, and psychiatric symptoms and their potential impact on brain stimulation and neuroimaging studies. It argues that researchers must adapt their study designs and screening processes to account for the confounding effects of long COVID and ensure the accuracy and reliability of their findings. To advance the understanding of this condition and its long-term effects on brain health, the review proposes a series of strategies, including the development of standardized screening tools, the investigation of underlying mechanisms, and the identification of risk factors and protective factors. It also emphasizes the importance of collaborative research efforts and international data sharing platforms in accelerating the pace of discovery and developing targeted interventions for individuals with long COVID. As the prevalence of this condition continues to grow, it is imperative that the neuroscience community comes together to address this challenge and support those affected by long COVID.

Primary Health Care Case-Management Nurses during the COVID-19 Pandemic: A Qualitative Study

The COVID-19 has caused high morbidity and mortality in vulnerable people, such as those affected by chronic diseases, and case-management nurses (CMNs) are reference professionals for their health care and management. The objective of this study is to better understand the discourse, experiences, and feelings about the professional performance of CMNs during the pandemic. A qualitative study was conducted by conducting semi-structured interviews with CMNs (n = 31) from the province of Seville (Spain) and performing a narrative discourse analysis. The Atlas Ti 6.2 software program was used. Two categories were defined: 1. CMNs' competencies (76 verbatim testimonies); and 2. Consequences of the COVID-19 pandemic (61 verbatim testimonies). This study was granted due permission by the Research Ethics Committee belonging to the University of Seville, under protocol code: 1139-N-22. The pandemic caused an increase in CMNs' workload, and they had to assume their usual care tasks for vulnerable populations in addition to simultaneously prioritizing assistance in nursing homes. We can highlight CMNs' adaptation to the pandemic situation and to these new requirements in the context of their significant social commitment to the advanced practice of the profession, a commitment that is closely related to leadership. We should also indicate that interpersonal relationships were improved, and that there was technological progress. Some CMNs mentioned an increase in their workload and reported experiencing burnout syndrome. We conclude that CMNs' management of health care during the pandemic has been extraordinary, especially in regard to the most vulnerable populations of patients, including individuals with chronic diseases and institutionalized older adults, a fact that has been valued by the institutions and by society in general.

Systemic inflammation relates to neuroaxonal damage associated with long-term cognitive dysfunction in COVID-19 patients

BACKGROUND AND OBJECTIVES

Cognitive deficits are increasingly recognized as a long-term sequela of severe COVID-19. The underlying processes and molecular signatures associated with these long-term neurological sequalae of COVID-19 remain largely unclear, but may be related to systemic inflammation-induced effects on the brain. We studied the systemic inflammation-brain interplay and its relation to development of long-term cognitive impairment in patients who survived severe COVID-19. Trajectories of systemic inflammation and neuroaxonal damage blood biomarkers during ICU admission were analyzed and related to long-term cognitive outcomes.

METHODS

Prospective longitudinal cohort study of patients with severe COVID-19 surviving ICU admission. During admission, blood was sampled consecutively to assess levels of inflammatory cytokines and neurofilament light chain (NfL) using an ultrasensitive multiplex Luminex assay and single molecule array technique (Simoa). Cognitive functioning was evaluated using a comprehensive neuropsychological assessment six months after ICU-discharge.

RESULTS

Ninety-six patients (median [IQR] age 61 [55-69] years) were enrolled from March 2020 to June 2021 and divided into two cohorts: those who received no COVID-19-related immunotherapy (n = 28) and those treated with either dexamethasone or dexamethasone and tocilizumab (n = 68). Plasma NfL concentrations increased in 95 % of patients during their ICU stay, from median [IQR] 23 [18-38] pg/mL at admission to 250 [160-271] pg/mL after 28 days, p < 0.001. Besides age, glomerular filtration rate, immunomodulatory treatment, and C-reactive protein, more specific markers of systemic inflammation at day 14 (i.e., interleukin (IL)-8, tumour necrosis factor, and IL-1 receptor antagonist) were significant predictors of blood NfL levels at day 14 of ICU admission (R2 = 44 %, p < 0.001), illustrating the association between sustained systemic inflammation and neuroaxonal damage. Twenty-six patients (27 %) exhibited cognitive impairment six months after discharge from the ICU. NfL concentrations showed a more pronounced increase in patients that developed cognitive impairment (p = 0.03). Higher NfL predicted poorer outcome in information processing speed (Trail Making Test A, r = -0.26, p = 0.01; Letter Digit Substitution Test, r = -0.24, p = 0.02).

DISCUSSION

Prolonged systemic inflammation in critically ill COVID-19 patients is related to neuroaxonal damage and subsequent long-term cognitive impairment. Moreover, our findings suggest that plasma NfL concentrations during ICU stay may possess prognostic value in predicting future long-term cognitive impairment in patients that survived severe COVID-19.

SARS-CoV-2's brain impact: revealing cortical and cerebellar differences via cluster analysis in COVID-19 recovered patients

BACKGROUND

COVID-19 is a disease known for its neurological involvement. SARS-CoV-2 infection triggers neuroinflammation, which could significantly contribute to the development of long-term neurological symptoms and structural alterations in the gray matter. However, the existence of a consistent pattern of cerebral atrophy remains uncertain.

OBJECTIVE

Our study aimed to identify patterns of brain involvement in recovered COVID-19 patients and explore potential relationships with clinical variables during hospitalization.

METHODOLOGY

In this study, we included 39 recovered patients and 39 controls from a pre-pandemic database to ensure their non-exposure to the virus. We obtained clinical data of the patients during hospitalization, and 3 months later; in addition we obtained T1-weighted magnetic resonance images and performed standard screening cognitive tests.

RESULTS

We identified two groups of recovered patients based on a cluster analysis of the significant cortical thickness differences between patients and controls. Group 1 displayed significant cortical thickness differences in specific cerebral regions, while Group 2 exhibited significant differences in the cerebellum, though neither group showed cognitive deterioration at the group level. Notably, Group 1 showed a tendency of higher D-dimer values during hospitalization compared to Group 2, prior to p-value correction.

CONCLUSION

This data-driven division into two groups based on the brain structural differences, and the possible link to D-dimer values may provide insights into the underlying mechanisms of SARS-COV-2 neurological disruption and its impact on the brain during and after recovery from the disease.

COVID-19 and the brain: understanding the pathogenesis and consequences of neurological damage

SARS-CoV-2 has been known remarkably since December 2019 as a strain of pathogenic coronavirus. Starting from the earlier stages of the COVID-19 pandemic until now, we have witnessed many cases of neurological damage caused by SARS-CoV-2. There are many studies and research conducted on COVID-19-positive-patients that have found brain-related abnormalities with clear neurological symptoms, ranging from simple headaches to life-threatening strokes. For treating neurological damage, knowing the actual pathway or mechanism of causing brain damage via SARS-CoV-2 is very important. For this reason, we have tried to explain the possible pathways of brain damage due to SARS-CoV-2 with mechanisms and illustrations. The SARS-CoV-2 virus enters the human body by binding to specific ACE2 receptors in the targeted cells, which are present in the glial cells and CNS neurons of the human brain. It is found that direct and indirect infections with SARS-CoV-2 in the brain result in endothelial cell death, which alters the BBB tight junctions. These probable alterations can be the reason for the excessive transmission and pathogenicity of SARS-CoV-2 in the human brain. In this precise review, we have tried to demonstrate the neurological symptoms in the case of COVID-19-positive-patients and the possible mechanisms of neurological damage, along with the treatment options for brain-related abnormalities. Knowing the transmission mechanism of SARS-CoV-2 in the human brain can assist us in generating novel treatments associated with neuroinflammation in other brain diseases.

The SARS-CoV-2 spike glycoprotein interacts with MAO-B and impairs mitochondrial energetics

SARS-CoV-2 infection is associated with both acute and post-acute neurological symptoms. Emerging evidence suggests that SARS-CoV-2 can alter mitochondrial metabolism, suggesting that changes in brain metabolism may contribute to the development of acute and post-acute neurological complications. Monoamine oxidase B (MAO-B) is a flavoenzyme located on the outer mitochondrial membrane that catalyzes the oxidative deamination of monoamine neurotransmitters. Computational analyses have revealed high similarity between the SARS-CoV-2 spike glycoprotein receptor binding domain on the ACE2 receptor and MAO-B, leading to the hypothesis that SARS-CoV-2 spike glycoprotein may alter neurotransmitter metabolism by interacting with MAO-B. Our results empirically establish that the SARS-CoV-2 spike glycoprotein interacts with MAO-B, leading to increased MAO-B activity in SH-SY5Y neuron-like cells. Common to neurodegenerative disease pathophysiological mechanisms, we also demonstrate that the spike glycoprotein impairs mitochondrial bioenergetics, induces oxidative stress, and perturbs the degradation of depolarized aberrant mitochondria through mitophagy. Our findings also demonstrate that SH-SY5Y neuron-like cells expressing the SARS-CoV-2 spike protein were more susceptible to MPTP-induced necrosis, likely necroptosis. Together, these results reveal novel mechanisms that may contribute to SARS-CoV-2-induced neurodegeneration.

Continued Infarction Growth and Penumbral Consumption After Reperfusion in Vaccine-Naive Patients With COVID-19: A Case-Control Study

BACKGROUND. Neurologic sequelae of SARS-CoV-2 include potentially malignant cerebrovascular events arising from complex hemodynamic, hematologic, and inflammatory processes occurring in concert. OBJECTIVE. This study concerns the hypothesis that despite angiographic reperfusion COVID-19 promotes continued consumption of at-risk tissue volumes after acute ischemic stroke (AIS), yielding critical insights into prognostication and monitoring paradigms in vaccine-naive patients experiencing AIS. METHODS. This retrospective study compared 100 consecutive COVID-19 patients with AIS presenting between March 2020 and April 2021 with a contemporaneous cohort of 282 AIS patients without COVID-19. Reperfusion classes were dichotomized into positive (extended thrombolysis in cerebral ischemia [eTICI] score = 2c-3) and negative (eTICI score < 2c) groups. All patients underwent endovascular therapy after initial CT perfusion imaging (CTP) to document infarction core and total hypoperfusion volumes. RESULTS. Ten COVID-positive (mean age ± SD, 67 ± 12 years; seven men, three women) and 144 COVID-negative patients (mean age, 71 ± 16 years; 76 men, 68 women) undergoing endovascular reperfusion, with antecedent CTP and follow-up imaging, comprised the final dataset. Initial infarction core and total hypoperfusion volumes (mean ± SD) were 1.5 ± 18 mL and 85 ± 100 mL in COVID-negative patients and 30.5 ± 34 mL and 117 ± 80.5 mL in COVID-positive patients, respectively. Final infarction volumes were significantly larger in patients with COVID-19, with median volumes of 77.8 mL versus 18.2 mL among control patients (p = .01), as were normalized measures of infarction growth relative to baseline infarction volume (p = .05). In adjusted logistic parametric regression models, COVID positivity emerged as a significant predictor for continued infarct growth (OR, 5.10 [95% CI, 1.00-25.95]; p = .05). CONCLUSION. These findings support the potentially aggressive clinical course of cerebrovascular events in patients with COVID-19, suggesting greater infarction growth and ongoing consumption of at-risk tissues, even after angiographic reperfusion. CLINICAL IMPACT. SARS-CoV-2 infection may promote continued infarction progression despite angiographic reperfusion in vaccine-naive patients with large-vessel occlusion AIS. The findings carry potential implications for prognostication, treatment selection, and surveillance for infarction growth among revascularized patients in future waves of infection by novel viral strains.

Infection with COVID-19 is no longer a public emergency: But what about degenerative dementia?

Although no longer considered a public health threat, post-COVID cognitive syndrome continues to impact on a considerable proportion of individuals who were infected with COVID-19. Recent studies have also suggested that COVID may be represent a critical risk factor for the development of Alzheimer's disease (AD). We compared 17 COVID patients with 20 controls and evaluated the effects of COVID-19 on general cognitive performance, hippocampal volume, and connections using structural and seed-based connectivity analysis. We showed that COVID patients exhibited considerably worse cognitive functioning and increased hippocampal connectivity supported by the strong correlation between hippocampal connectivity and cognitive scores. Our findings of higher hippocampal connectivity with no observable hippocampal morphological changes even in mild COVID cases may be represent evidence of a prestructural compensatory mechanism for stimulating additional neuronal resources to combat cognitive dysfunction as recently shown for the prodromal stages of degenerative cognitive disorders. Our findings may be also important in light of recent data showing that other viral infections as well as COVID may constitute a critical risk factor for the development of AD. To our knowledge, this is the first study that investigated network differences in COVID patients, with a particular focus on compensatory hippocampal connectivity.

The essential role of neuroimaging in diagnosing and managing cerebrovascular disease in Africa: a review

BACKGROUND

Cerebrovascular disease is a significant cause of morbidity and mortality in Africa, and using neuroimaging techniques has improved the diagnosis and management of this disease. However, there is a lack of comprehensive reviews of the role and effectiveness of neuroimaging techniques in the African context.

METHODS

We reviewed the literature to evaluate the role of neuroimaging in diagnosing and managing cerebrovascular disease in Africa. Our search included electronic databases such as PubMed, Scopus, and Google Scholar from 2000 to April 2023. We included peer-reviewed studies written in English that reported on the use of neuroimaging in diagnosing and managing cerebrovascular disease in African populations. We excluded non-peer-reviewed articles, letters, editorials, and studies unrelated to cerebrovascular disease, neuroimaging, or Africa. A total of 102 potential articles were identified; after applying our exclusion criteria and removing duplicated articles, 51 articles were reviewed.

RESULTS

Our findings suggest that neuroimaging techniques such as CT, MRI, and Skull x-ray play a crucial role in diagnosing and managing cerebrovascular disease in Africa. CT and MRI were the most commonly used techniques, with CT being more widely available and less expensive than MRI. However, challenges to using neuroimaging in Africa include the high cost of equipment and maintenance, lack of trained personnel, and inadequate infrastructure. These challenges limit the widespread use of neuroimaging in diagnosing and managing cerebrovascular disease in Africa.

CONCLUSION

Neuroimaging techniques are essential for diagnosing and managing cerebrovascular disease in Africa, but challenges to their use must be addressed to improve healthcare outcomes. Our policy recommendations can help improve the availability and accessibility of neuroimaging services in Africa.

Brain imaging and neuropsychological assessment of individuals recovered from a mild to moderate SARS-CoV-2 infection

As severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) infections have been shown to affect the central nervous system, the investigation of associated alterations of brain structure and neuropsychological sequelae is crucial to help address future health care needs. Therefore, we performed a comprehensive neuroimaging and neuropsychological assessment of 223 nonvaccinated individuals recovered from a mild to moderate SARS-CoV-2 infection (100 female/123 male, age [years], mean ± SD, 55.54 ± 7.07; median 9.7 mo after infection) in comparison with 223 matched controls (93 female/130 male, 55.74 ± 6.60) within the framework of the Hamburg City Health Study. Primary study outcomes were advanced diffusion MRI measures of white matter microstructure, cortical thickness, white matter hyperintensity load, and neuropsychological test scores. Among all 11 MRI markers tested, significant differences were found in global measures of mean diffusivity (MD) and extracellular free water which were elevated in the white matter of post-SARS-CoV-2 individuals compared to matched controls (free water: 0.148 ± 0.018 vs. 0.142 ± 0.017, P < 0.001; MD [10-3 mm2/s]: 0.747 ± 0.021 vs. 0.740 ± 0.020, P < 0.001). Group classification accuracy based on diffusion imaging markers was up to 80%. Neuropsychological test scores did not significantly differ between groups. Collectively, our findings suggest that subtle changes in white matter extracellular water content last beyond the acute infection with SARS-CoV-2. However, in our sample, a mild to moderate SARS-CoV-2 infection was not associated with neuropsychological deficits, significant changes in cortical structure, or vascular lesions several months after recovery. External validation of our findings and longitudinal follow-up investigations are needed.

The Association between Dysnatraemia during Hospitalisation and Post-COVID-19 Mental Fatigue

COVID-19 may induce short- and long-term cognitive failures after recovery, but the underlying risk factors are still controversial. Here, we investigated whether (i) the odds of experiencing persistent cognitive failures differ based on the patients' disease course severity and sex at birth; and (ii) the patients' electrolytic profile in the acute stage represents a risk factor for persistent cognitive failures. We analysed data from 204 patients suffering from COVID-19 and hospitalised during the first pandemic wave. According to the 7-point WHO-OS scale, their disease course was classified as severe or mild. We investigated the presence of persistent cognitive failures collected after hospital discharge, while electrolyte profiles were collected during hospitalisation. The results showed that females who suffered from a mild course compared to a severe course of COVID-19 had a higher risk of presenting with persistent mental fatigue after recovery. Furthermore, in females who suffered from a mild course of COVID-19, persistent mental fatigue was related to electrolyte imbalance, in terms of both hypo- and hypernatremia, during hospitalisation in the acute phase. These findings have important implications for the clinical management of hospitalised COVID-19 patients. Attention should be paid to potential electrolyte imbalances, mainly in females suffering from mild COVID-19.

Brain Volume Changes after COVID-19 Compared to Healthy Controls by Artificial Intelligence-Based MRI Volumetry

Cohort studies that quantify volumetric brain data among individuals with different levels of COVID-19 severity are presently limited. It is still uncertain whether there exists a potential correlation between disease severity and the effects of COVID-19 on brain integrity. Our objective was to assess the potential impact of COVID-19 on measured brain volume in patients with asymptomatic/mild and severe disease after recovery from infection, compared with healthy controls, using artificial intelligence (AI)-based MRI volumetry. A total of 155 participants were prospectively enrolled in this IRB-approved analysis of three cohorts with a mild course of COVID-19 (n = 51, MILD), a severe hospitalised course (n = 48, SEV), and healthy controls (n = 56, CTL) all undergoing a standardised MRI protocol of the brain. Automated AI-based determination of various brain volumes in mL and calculation of normalised percentiles of brain volume was performed with mdbrain software, using a 3D T1-weighted magnetisation-prepared rapid gradient echo (MPRAGE) sequence. The automatically measured brain volumes and percentiles were analysed for differences between groups. The estimated influence of COVID-19 and demographic/clinical variables on brain volume was determined using multivariate analysis. There were statistically significant differences in measured brain volumes and percentiles of various brain regions among groups, even after the exclusion of patients undergoing intensive care, with significant volume reductions in COVID-19 patients, which increased with disease severity (SEV > MILD > CTL) and mainly affected the supratentorial grey matter, frontal and parietal lobes, and right thalamus. Severe COVID-19 infection, in addition to established demographic parameters such as age and sex, was a significant predictor of brain volume loss upon multivariate analysis. In conclusion, neocortical brain degeneration was detected in patients who had recovered from SARS-CoV-2 infection compared to healthy controls, worsening with greater initial COVID-19 severity and mainly affecting the fronto-parietal brain and right thalamus, regardless of ICU treatment. This suggests a direct link between COVID-19 infection and subsequent brain atrophy, which may have major implications for clinical management and future cognitive rehabilitation strategies.

Perceived Cognitive Deficits in Patients With Symptomatic SARS-CoV-2 and Their Association With Post-COVID-19 Condition

Importance

Neuropsychiatric symptoms are common in acute SARS-CoV-2 infection and in post-COVID-19 condition (PCC; colloquially known as long COVID), but the association between early presenting neuropsychiatric symptoms and PCC is unknown.

Objective

To describe the characteristics of patients with perceived cognitive deficits within the first 4 weeks of SARS-CoV-2 infection and the association of those deficits with PCC symptoms.

Design, Setting, and Participants

This prospective cohort study was conducted from April 2020 to February 2021, with follow-up of 60 to 90 days. The cohort consisted of adults enrolled in the University of California, Los Angeles, SARS-CoV-2 Ambulatory Program who had a laboratory-confirmed symptomatic SARS-CoV-2 infection and were either hospitalized in a University of California, Los Angeles, hospital or one of 20 local health care facilities, or were outpatients referred by a primary care clinician. Data analysis was performed from March 2022 to February 2023.

Exposure

Laboratory-confirmed SARS-CoV-2 infection.

Main Outcomes and Measures

Patients responded to surveys that included questions about perceived cognitive deficits modified from the Perceived Deficits Questionnaire, Fifth Edition, (ie, trouble being organized, trouble concentrating, and forgetfulness) and symptoms of PCC at 30, 60, and 90 days after hospital discharge or initial laboratory-confirmed infection of SARS-CoV-2. Perceived cognitive deficits were scored on a scale from 0 to 4. Development of PCC was determined by patient self-report of persistent symptoms 60 or 90 days after initial SARS-CoV-2 infection or hospital discharge.

Results

Of 1296 patients enrolled in the program, 766 (59.1%) (mean [SD] age, 60.0 [16.7] years; 399 men [52.1%]; 317 Hispanic/Latinx patients [41.4%]) completed the perceived cognitive deficit items at 30 days after hospital discharge or outpatient diagnosis. Of the 766 patients, 276 (36.1%) perceived a cognitive deficit, with 164 (21.4%) having a mean score of greater than 0 to 1.5 and 112 patients (14.6 %) having a mean score greater than 1.5. Prior cognitive difficulties (odds ratio [OR], 1.46; 95% CI, 1.16-1.83) and diagnosis of depressive disorder (OR, 1.51; 95% CI, 1.23-1.86) were associated with report of a perceived cognitive deficit. Patients reporting perceived cognitive deficits in the first 4 weeks of SARS-CoV-2 infection were more likely to report symptoms of PCC than those without perceived cognitive deficits (118 of 276 patients [42.8%] vs 105 of 490 patients [21.4%]; χ21, 38.9; P < .001). Adjusting for demographic and clinical factors, perceived cognitive deficits in the first 4 weeks of SARS-CoV-2 were associated with PCC symptoms (patients with a cognitive deficit score of >0 to 1.5: OR, 2.42; 95% CI, 1.62-3.60; patients with cognitive deficit score >1.5: OR, 2.97; 95% CI, 1.86-4.75) compared to patients who reported no perceived cognitive deficits.

Conclusions and Relevance

These findings suggest that patient-reported perceived cognitive deficits in the first 4 weeks of SARS-CoV-2 infection are associated with PCC symptoms and that there may be an affective component to PCC in some patients. The underlying reasons for PCC merit additional exploration.

Multifactorial White Matter Damage in the Acute Phase and Pre-Existing Conditions May Drive Cognitive Dysfunction after SARS-CoV-2 Infection: Neuropathology-Based Evidence

BACKGROUND

There is an urgent need to better understand the mechanisms underlying acute and long-term neurological symptoms after COVID-19. Neuropathological studies can contribute to a better understanding of some of these mechanisms.

METHODS

We conducted a detailed postmortem neuropathological analysis of 32 patients who died due to COVID-19 during 2020 and 2021 in Austria.

RESULTS

All cases showed diffuse white matter damage with a diffuse microglial activation of a variable severity, including one case of hemorrhagic leukoencephalopathy. Some cases revealed mild inflammatory changes, including olfactory neuritis (25%), nodular brainstem encephalitis (31%), and cranial nerve neuritis (6%), which were similar to those observed in non-COVID-19 severely ill patients. One previously immunosuppressed patient developed acute herpes simplex encephalitis. Acute vascular pathologies (acute infarcts 22%, vascular thrombosis 12%, diffuse hypoxic-ischemic brain damage 40%) and pre-existing small vessel diseases (34%) were frequent findings. Moreover, silent neurodegenerative pathologies in elderly persons were common (AD neuropathologic changes 32%, age-related neuronal and glial tau pathologies 22%, Lewy bodies 9%, argyrophilic grain disease 12.5%, TDP43 pathology 6%).

CONCLUSIONS

Our results support some previous neuropathological findings of apparently multifactorial and most likely indirect brain damage in the context of SARS-CoV-2 infection rather than virus-specific damage, and they are in line with the recent experimental data on SARS-CoV-2-related diffuse white matter damage, microglial activation, and cytokine release.

Effects of post-acute COVID-19 syndrome on the functional brain networks of non-hospitalized individuals

Introduction

The long-term impact of COVID-19 on brain function remains poorly understood, despite growing concern surrounding post-acute COVID-19 syndrome (PACS). The goal of this cross-sectional, observational study was to determine whether there are significant alterations in resting brain function among non-hospitalized individuals with PACS, compared to symptomatic individuals with non-COVID infection.

Methods

Data were collected for 51 individuals who tested positive for COVID-19 (mean age 41±12 yrs., 34 female) and 15 controls who had cold and flu-like symptoms but tested negative for COVID-19 (mean age 41±14 yrs., 9 female), with both groups assessed an average of 4-5 months after COVID testing. None of the participants had prior neurologic, psychiatric, or cardiovascular illness. Resting brain function was assessed via functional magnetic resonance imaging (fMRI), and self-reported symptoms were recorded.

Results

Individuals with COVID-19 had lower temporal and subcortical functional connectivity relative to controls. A greater number of ongoing post-COVID symptoms was also associated with altered functional connectivity between temporal, parietal, occipital and subcortical regions.

Discussion

These results provide preliminary evidence that patterns of functional connectivity distinguish PACS from non-COVID infection and correlate with the severity of clinical outcome, providing novel insights into this highly prevalent disorder.

Imaging and neuropathological findings in patients with Post COVID-19 Neurological Syndrome-A review

Post COVID-19 syndrome is determined as signs and symptoms that appear during or after an infection consistent with SARS-CoV-2 disease, persist for more than 12 weeks and are not explained by an alternative diagnosis. This review presents the neuropathological findings and imaging findings in Post COVID-19 Neurological Syndrome: the focal point is on the manifestations of involvement evident on brain and spine imaging.

Cortical Grey matter volume depletion links to neurological sequelae in post COVID-19 "long haulers"

OBJECTIVE

COVID-19 (SARS-CoV-2) has been associated with neurological sequelae even in those patients with mild respiratory symptoms. Patients experiencing cognitive symptoms such as "brain fog" and other neurologic sequelae for 8 or more weeks define "long haulers". There is limited information regarding damage to grey matter (GM) structures occurring in COVID-19 "long haulers". Advanced imaging techniques can quantify brain volume depletions related to COVID-19 infection which is important as conventional Brain MRI often fails to identify disease correlates. 3-dimensional voxel-based morphometry (3D VBM) analyzes, segments and quantifies key brain volumes allowing comparisons between COVID-19 "long haulers" and normative data drawn from healthy controls, with values based on percentages of intracranial volume.

METHODS

This is a retrospective single center study which analyzed 24 consecutive COVID-19 infected patients with long term neurologic symptoms. Each patient underwent Brain MRI with 3D VBM at median time of 85 days following laboratory confirmation. All patients had relatively mild respiratory symptoms not requiring oxygen supplementation, hospitalization, or assisted ventilation. 3D VBM was obtained for whole brain and forebrain parenchyma, cortical grey matter (CGM), hippocampus, and thalamus.

RESULTS

The results demonstrate a statistically significant depletion of CGM volume in 24 COVID-19 infected patients. Reduced CGM volume likely influences their long term neurological sequelae and may impair post COVID-19 patient's quality of life and productivity.

CONCLUSION

This study contributes to understanding effects of COVID-19 infection on patient's neurocognitive and neurological function, with potential for producing serious long term personal and economic consequences, and ongoing challenges to public health systems.

COVID-19 as a Risk Factor for Alzheimer's Disease

Severe acute respiratory disease coronavirus 2 (SARS-CoV-2) is responsible for the coronavirus disease 2019 (COVID-19) pandemic. Although a primarily respiratory disease, recent reports indicate that it also affects the central nervous system (CNS). Over 25% of COVID-19 patients report neurological symptoms such as memory loss, anosmia, hyposmia, confusion, and headaches. The neurological outcomes may be a result of viral entry into the CNS and/or resulting neuroinflammation, both of which underlie an elevated risk for Alzheimer's disease (AD). Herein, we ask: Is COVID-19 a risk factor for AD? To answer, we identify the literature and review mechanisms by which COVID-19-mediated neuroinflammation can contribute to the development of AD, evaluate the effects of acute versus chronic phases of infection, and lastly, discuss potential therapeutics to address the rising rates of COVID-19 neurological sequelae.

'Now I can bend and meet people virtually in my home': The experience of a remotely supervised online chair yoga intervention and visual socialisation among older adults with dementia

BACKGROUND

Little research has been conducted on telehealth-based interventions in older adults. There has been no study of the use of telehealth-based online chair yoga (CY) to improve physical activity and manage dementia symptoms and socialisation for older adults with dementia who are socially isolated.

OBJECTIVES

The study identified benefits, challenges and facilitators in participating in remotely supervised online CY from the perspective of older adults with dementia and their caregivers, including what would help them to participate in online interventions.

METHODS

In a qualitative descriptive design, four online focus groups (two pre-intervention and two post-intervention) conducted via videoconference explored the benefits, challenges and facilitators in participating in a remotely supervised twice-weekly, 8-week online CY intervention. A total of 17 participants (eight people with dementia and nine family caregivers) attended the focus groups. The data were subjected to thematic analysis.

RESULTS

Thematic analysis of data identified three themes from the perspectives of older adults with dementia and their caregivers: (a) benefits (e.g. sleep and relaxation, emotional regulation, flexibility, muscle strength, convenience, caregiver-participant connection), (b) challenges (e.g. technological setup) and (c) lessons learned (e.g. inclusion of caregiver, yoga instructor, visual cues, socialisation, safety). The online intervention was beneficial to participants, who reported that they wanted to continue home-based online CY practice.

CONCLUSION

Convenience was the major advantage for the participant to continue to practice online CY. The online intervention offered virtual socialisation, which could be significant for motivating older adults to continue the CY program.

IMPLICATIONS FOR PRACTICE

Gerontological nurses could add CY as a nonpharmacological component of a treatment plan and monitor older adults' progress during the online intervention. The home-based online CY intervention should be prioritised to promote health and wellness in socially isolated older adults with dementia.

Respiratory psychophysiology and COVID-19: A research agenda

After multiple waves of the COVID-19 pandemic, it has become clear that the impact of SARS-CoV-2 will carry on for years to come. Acutely infected patients show a broad range of disease severity, depending on virus variant, vaccination status, age and the presence of underlying medical and physical conditions, including obesity. Additionally, a large number of patients who have been infected with the virus present with post-COVID syndrome. In September 2020, the International Society for the Advancement of Respiratory Psychophysiology organized a virtual interest meeting on 'Respiratory research in the age of COVID-19', which aimed to discuss how research in respiratory psychophysiology could contribute to a better understanding of psychophysiological interactions in COVID-19. In the resulting current paper, we propose an interdisciplinary research agenda discussing selected research questions on acute and long-term neurobiological, physiological and psychological outcomes and mechanisms related to respiration and the airways in COVID-19, as well as research questions on comorbidity and potential treatment options, such as physical rehabilitation.

MRI Assessment of Cerebral Blood Flow in Nonhospitalized Adults Who Self-Isolated Due to COVID-19

BACKGROUND

Neurological symptoms associated with coronavirus disease 2019 (COVID-19), such as fatigue and smell/taste changes, persist beyond infection. However, little is known of brain physiology in the post-COVID-19 timeframe.

PURPOSE

To determine whether adults who experienced flu-like symptoms due to COVID-19 would exhibit cerebral blood flow (CBF) alterations in the weeks/months beyond infection, relative to controls who experienced flu-like symptoms but tested negative for COVID-19.

STUDY TYPE

Prospective observational.

POPULATION

A total of 39 adults who previously self-isolated at home due to COVID-19 (41.9 ± 12.6 years of age, 59% female, 116.5 ± 62.2 days since positive diagnosis) and 11 controls who experienced flu-like symptoms but had a negative COVID-19 diagnosis (41.5 ± 13.4 years of age, 55% female, 112.1 ± 59.5 since negative diagnosis).

FIELD STRENGTH AND SEQUENCES

A 3.0 T; T1-weighted magnetization-prepared rapid gradient and echo-planar turbo gradient-spin echo arterial spin labeling sequences.

ASSESSMENT

Arterial spin labeling was used to estimate CBF. A self-reported questionnaire assessed symptoms, including ongoing fatigue. CBF was compared between COVID-19 and control groups and between those with (n = 11) and without self-reported ongoing fatigue (n = 28) within the COVID-19 group.

STATISTICAL TESTS

Between-group and within-group comparisons of CBF were performed in a voxel-wise manner, controlling for age and sex, at a family-wise error rate of 0.05.

RESULTS

Relative to controls, the COVID-19 group exhibited significantly decreased CBF in subcortical regions including the thalamus, orbitofrontal cortex, and basal ganglia (maximum cluster size = 6012 voxels and maximum t-statistic = 5.21). Within the COVID-19 group, significant CBF differences in occipital and parietal regions were observed between those with and without self-reported on-going fatigue.

DATA CONCLUSION

These cross-sectional data revealed regional CBF decreases in the COVID-19 group, suggesting the relevance of brain physiology in the post-COVID-19 timeframe. This research may help elucidate the heterogeneous symptoms of the post-COVID-19 condition.

EVIDENCE LEVEL

2.

TECHNICAL EFFICACY

Stage 3.

Neurological Manifestations of SARS-CoV2 Infection: A Narrative Review

The COVID-19 virus frequently causes neurological complications. These have been described in various forms in adults and children. Headache, seizures, coma, and encephalitis are some of the manifestations of SARS-CoV-2-induced neurological impairment. Recent publications have revealed important aspects of viral pathophysiology and its involvement in nervous-system impairment in humans. We evaluated the latest literature describing the relationship between COVID-19 infection and the central nervous system. We searched three databases for observational and interventional studies in adults published between December 2019 and September 2022. We discussed in narrative form the neurological impairment associated with COVID-19, including clinical signs and symptoms, imaging abnormalities, and the pathophysiology of SARS-CoV2-induced neurological damage.

Olfactory and neurological outcomes of SARS-CoV-2 from acute infection to recovery

Educational objective

To investigate the impact of SARS-CoV-2 on sinonasal quality of life, olfaction, and cognition at different stages of viral infection and evaluate the association between olfaction and cognition in this population cohort.

Objectives

While olfactory dysfunction (OD) is a frequently reported symptom of COVID-19 (98% prevalence), neurocognitive symptoms are becoming more apparent as patients recover from infection. This study aims to address how different stages of infection [active infection (positive PCR test, symptomatic) vs. recovered (7 days post-symptoms)] compared to healthy control patients influence sinonasal quality of life, olfactory function, and cognition.

Study design

Prospective, longitudinal, case-control.

Methods

Participants completed the SNOT-22, University of Pennsylvania Smell Identification Test (UPSIT) and validated cognitive examinations to assess degree of smell loss and neurocognitive function at baseline and at 1 and 3 months for the active group and 3 months for the recovered group. Self-reported olfactory function and overall health metrics were also collected.

Results

The recovered group had the lowest average UPSIT score of 27.6 compared to 32.7 (active) and 32.6 (healthy control). 80% (n = 24) of the recovered patients and 56.3% (n = 9) of the active patients suffered from smell loss. In follow-up, the active group showed improvement in UPSIT scores while the recovered group scores worsened. In terms of neurocognitive performance, recovered patients had lower processing speed despite an improving UPSIT score.

Conclusion

SARS-CoV-2 infection was found to impact olfactory function in a delayed fashion with significant impact despite recovery from active infection. Although olfactory function improved, decrements in cognitive processing speed were detected in our cohort.

The impact of social isolation due to the COVID-19 pandemic on patients with dementia and caregivers

OBJECTIVE

Social distancing to limit COVID-19 transmission has led to extensive lifestyle changes, including for people with dementia (PWD). The aim of this study, therefore, was to assess the impact of lockdown on the mental health of PWD and their carers.

METHODS

Forty-five carers of PWD completed a telephone interview during the baseline assessment of the SOLITUDE study to gather information on life conditions and changes in symptoms of PWD during lockdown. Associations between changes in symptoms of PWD and carers' concerns and mental health were investigated.

RESULTS

About 44% of carers experienced anxiety and irritability and reported changes in behavioural and cognitive symptoms in PWD. These changes were associated with worse carers' mental health and concerns about faster disease progression (χ² = 13.542, p < 0.001).

CONCLUSION

COVID-19-related social isolation has had a negative impact on patients' and carers' mental health. Potential long-term neurocognitive consequences require further investigation.

Post-acute sequelae of SARS-CoV-2 infection: relationship of central nervous system manifestations with physical disability and systemic inflammation

BACKGROUND

Despite the multitude of clinical manifestations of post-acute sequelae of SARS-CoV-2 infection (PASC), studies applying statistical methods to directly investigate patterns of symptom co-occurrence and their biological correlates are scarce.

METHODS

We assessed 30 symptoms pertaining to different organ systems in 749 adults (age = 55 ± 14 years; 47% female) during in-person visits conducted at 6-11 months after hospitalization due to coronavirus disease 2019 (COVID-19), including six psychiatric and cognitive manifestations. Symptom co-occurrence was initially investigated using exploratory factor analysis (EFA), and latent variable modeling was then conducted using Item Response Theory (IRT). We investigated associations of latent variable severity with objective indices of persistent physical disability, pulmonary and kidney dysfunction, and C-reactive protein and D-dimer blood levels, measured at the same follow-up assessment.

RESULTS

The EFA extracted one factor, explaining 64.8% of variance; loadings were positive for all symptoms, and above 0.35 for 16 of them. The latent trait generated using IRT placed fatigue, psychiatric, and cognitive manifestations as the most discriminative symptoms (coefficients > 1.5, p < 0.001). Latent trait severity was associated with decreased body weight and poorer physical performance (coefficients > 0.240; p ⩽ 0.003), and elevated blood levels of C-reactive protein (coefficient = 0.378; 95% CI 0.215-0.541; p < 0.001) and D-dimer (coefficient = 0.412; 95% CI 0.123-0.702; p = 0.005). Results were similar after excluding subjects with pro-inflammatory comorbidities.

CONCLUSIONS

Different symptoms that persist for several months after moderate or severe COVID-19 may unite within one latent trait of PASC. This trait is dominated by fatigue and psychiatric symptoms, and is associated with objective signs of physical disability and persistent systemic inflammation.

Long COVID and its Management

The pandemic of COVID-19 is the biggest public health crisis in 21st Century. Besides the acute symptoms after infection, patients and society are also being challenged by the long-term health complications associated with COVID-19, commonly known as long COVID. While health professionals work hard to find proper treatments, large amount of knowledge has been accumulated in recent years. In order to deal with long COVID efficiently, it is important for people to keep up with current progresses and take proactive actions on long COVID. For this purpose, this review will first introduce the general background of long COVID, and then discuss its risk factors, diagnostic indicators and management strategies. This review will serve as a useful resource for people to understand and prepare for long COVID that will be with us in the foreseeable future.

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

There is strong evidence of brain-related abnormalities in COVID-191–13. However, it remains unknown whether the impact of SARS-CoV-2 infection can be detected in milder cases, and whether this can reveal possible mechanisms contributing to brain pathology. Here we investigated brain changes in 785 participants of UK Biobank (aged 51–81 years) who were imaged twice using magnetic resonance imaging, including 401 cases who tested positive for infection with SARS-CoV-2 between their two scans—with 141 days on average separating their diagnosis and the second scan—as well as 384 controls. The availability of pre-infection imaging data reduces the likelihood of pre-existing risk factors being misinterpreted as disease effects. We identified significant longitudinal effects when comparing the two groups, including (1) a greater reduction in grey matter thickness and tissue contrast in the orbitofrontal cortex and parahippocampal gyrus; (2) greater changes in markers of tissue damage in regions that are functionally connected to the primary olfactory cortex; and (3) a greater reduction in global brain size in the SARS-CoV-2 cases. The participants who were infected with SARS-CoV-2 also showed on average a greater cognitive decline between the two time points. Importantly, these imaging and cognitive longitudinal effects were still observed after excluding the 15 patients who had been hospitalised. These mainly limbic brain imaging results may be the in vivo hallmarks of a degenerative spread of the disease through olfactory pathways, of neuroinflammatory events, or of the loss of sensory input due to anosmia. Whether this deleterious effect can be partially reversed, or whether these effects will persist in the long term, remains to be investigated with additional follow-up.

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

There is strong evidence of brain-related abnormalities in COVID-191-13. However, it remains unknown whether the impact of SARS-CoV-2 infection can be detected in milder cases, and whether this can reveal possible mechanisms contributing to brain pathology. Here we investigated brain changes in 785 participants of UK Biobank (aged 51-81 years) who were imaged twice using magnetic resonance imaging, including 401 cases who tested positive for infection with SARS-CoV-2 between their two scans-with 141 days on average separating their diagnosis and the second scan-as well as 384 controls. The availability of pre-infection imaging data reduces the likelihood of pre-existing risk factors being misinterpreted as disease effects. We identified significant longitudinal effects when comparing the two groups, including (1) a greater reduction in grey matter thickness and tissue contrast in the orbitofrontal cortex and parahippocampal gyrus; (2) greater changes in markers of tissue damage in regions that are functionally connected to the primary olfactory cortex; and (3) a greater reduction in global brain size in the SARS-CoV-2 cases. The participants who were infected with SARS-CoV-2 also showed on average a greater cognitive decline between the two time points. Importantly, these imaging and cognitive longitudinal effects were still observed after excluding the 15 patients who had been hospitalised. These mainly limbic brain imaging results may be the in vivo hallmarks of a degenerative spread of the disease through olfactory pathways, of neuroinflammatory events, or of the loss of sensory input due to anosmia. Whether this deleterious effect can be partially reversed, or whether these effects will persist in the long term, remains to be investigated with additional follow-up.

Cognitive decline and brainstem hypometabolism in long COVID: A case series

OBJECTIVE

To assess FDG cerebral PET in patients suffering from cognitive impairment linked to Long COVID. The COVID pandemic has affected dozens of millions of people around the world and has resulted in the deaths of more than 3 million people. Following the acute forms, it has been reported sometimes long forms of COVID, with involvements of several organs including the brain. Neurological complications can include cognitive disturbances (brain fog) that are very common and can seriously disturb the life of patients.

METHODS

Fluorodeoxyglucose PETs were performed in 3 patients with cognitive decline following COVID infection.

RESULTS

We report here 3 cases of brain fog with major hypometabolic areas of the pons revealed by the cerebral FDG PET.

CONCLUSION

The dysfunction of the locus coeruleus in these patients could partly explain the cognitive disorders observed. Further studies involving larger cohorts of patients suffering from cognitive dysfunction will be needed to determine if the brainstem is frequently affected in these patients.

Visual interpretation of brain hypometabolism related to neurological long COVID: a French multicentric experience

Background

This multicentre study aimed to provide a qualitative and consensual description of brain hypometabolism observed through the visual analysis of ¹⁸F-FDG PET images of patients with suspected neurological long COVID, regarding the previously reported long-COVID hypometabolic pattern involving hypometabolism in the olfactory bulbs and other limbic/paralimbic regions, as well as in the brainstem and cerebellum.

Methods

From the beginning of August 2021 to the end of October 2021, the brain ¹⁸F-FDG PET scans of patients referred for suspected neurological long COVID with positive reverse transcription polymerase chain reaction (RT-PCR) and/or serology tests for SARS-CoV-2 infection were retrospectively reviewed in three French nuclear medicine departments (143 patients; 47.4 years old ± 13.6; 98 women). Experienced nuclear physicians from each department classified brain ¹⁸F-FDG PET scans according to the same visual interpretation analysis as being normal, mildly to moderately (or incompletely) affected, or otherwise severely affected within the previously reported long-COVID hypometabolic pattern.

Results

On the 143 brain ¹⁸F-FDG PET scans performed during this 3-month period, 53% of the scans were visually interpreted as normal, 21% as mildly to moderately or incompletely affected, and 26% as severely affected according to the COVID hypometabolic pattern. On average, PET scans were performed at 10.9 months from symptom onset (± 4.8). Importantly, this specific hypometabolic pattern was similarly identified in the three nuclear medicine departments. Typical illustrative examples are provided to help nuclear physicians interpret long-COVID profiles.

Conclusion

The proposed PET metabolic pattern is easily identified upon visual interpretation in clinical routine for approximately one half of patients with suspected neurological long COVID, requiring special consideration for frontobasal paramedian regions, the brainstem and the cerebellum, and certainly further adapted follow-up and medical care, while the second half of patients have normal brain PET metabolism on average 10.9 months from symptom onset.

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

There is strong evidence for brain-related abnormalities in COVID-19 1-13 . It remains unknown however whether the impact of SARS-CoV-2 infection can be detected in milder cases, and whether this can reveal possible mechanisms contributing to brain pathology. Here, we investigated brain changes in 785 UK Biobank participants (aged 51-81) imaged twice, including 401 cases who tested positive for infection with SARS-CoV-2 between their two scans, with 141 days on average separating their diagnosis and second scan, and 384 controls. The availability of pre-infection imaging data reduces the likelihood of pre-existing risk factors being misinterpreted as disease effects. We identified significant longitudinal effects when comparing the two groups, including: (i) greater reduction in grey matter thickness and tissue-contrast in the orbitofrontal cortex and parahippocampal gyrus, (ii) greater changes in markers of tissue damage in regions functionally-connected to the primary olfactory cortex, and (iii) greater reduction in global brain size. The infected participants also showed on average larger cognitive decline between the two timepoints. Importantly, these imaging and cognitive longitudinal effects were still seen after excluding the 15 cases who had been hospitalised. These mainly limbic brain imaging results may be the in vivo hallmarks of a degenerative spread of the disease via olfactory pathways, of neuroinflammatory events, or of the loss of sensory input due to anosmia. Whether this deleterious impact can be partially reversed, or whether these effects will persist in the long term, remains to be investigated with additional follow up.

OUP accepted manuscript

Lack of awareness of cognitive impairment (i.e. anosognosia) could be a key factor for distinguishing between neuropsychological post-COVID-19 condition phenotypes. In this context, the 2-fold aim of the present study was to (i) establish the prevalence of anosognosia for memory impairment, according to the severity of the infection in the acute phase and (ii) determine whether anosognosic patients with post-COVID syndrome have a different cognitive and psychiatric profile from nosognosic patients, with associated differences in brain functional connectivity. A battery of neuropsychological, psychiatric, olfactory, dyspnoea, fatigue and quality-of-life tests was administered 227.07 ± 42.69 days post-SARS-CoV-2 infection to 102 patients (mean age: 56.35 years, 65 men, no history of neurological, psychiatric, neuro-oncological or neurodevelopmental disorder prior to infection) who had experienced either a mild (not hospitalized; n = 45), moderate (conventional hospitalization; n = 34) or severe (hospitalization with intensive care unit stay and mechanical ventilation; n = 23) presentation in the acute phase. Patients were first divided into two groups according to the presence or absence of anosognosia for memory deficits (26 anosognosic patients and 76 nosognosic patients). Of these, 49 patients underwent an MRI. Structural images were visually analysed, and statistical intergroup analyses were then performed on behavioural and functional connectivity measures. Only 15.6% of patients who presented mild disease displayed anosognosia for memory dysfunction, compared with 32.4% of patients with moderate presentation and 34.8% of patients with severe disease. Compared with nosognosic patients, those with anosognosia for memory dysfunction performed significantly more poorly on objective cognitive and olfactory measures. By contrast, they gave significantly more positive subjective assessments of their quality of life, psychiatric status and fatigue. Interestingly, the proportion of patients exhibiting a lack of consciousness of olfactory deficits was significantly higher in the anosognosic group. Functional connectivity analyses revealed a significant decrease in connectivity, in the anosognosic group as compared with the nosognosic group, within and between the following networks: the left default mode, the bilateral somatosensory motor, the right executive control, the right salient ventral attention and the bilateral dorsal attention networks, as well as the right Lobules IV and V of the cerebellum. Lack of awareness of cognitive disorders and, to a broader extent, impairment of the self-monitoring brain system, may be a key factor for distinguishing between the clinical phenotypes of post-COVID syndrome with neuropsychological deficits.

The Impact of Social Isolation Due to COVID-19 on Symptom Progression in People With Dementia: Findings of the SOLITUDE Study

BACKGROUND

People with dementia (PWD) are vulnerable to abrupt changes to daily routines. The lockdown enforced on the 23rd of March 2020 in the UK to contain the expansion of the COVID-19 pandemic limited opportunities for PWD to access healthcare services and socialise. The SOLITUDE study explored the potential long-term effects of lockdown on PWD's symptoms and carers' burden.

METHODS

Forty-five carers and 36 PWD completed a telephone-based assessment at recruitment (T0) and after 3 (T1) and 6 months (T2). PWD completed measures validated for telephonic evaluations of cognition and depression. Carers completed questionnaires on their burden and on PWD's health and answered a customised interview on symptom changes observed in the initial months of lockdown. Longitudinal changes were investigated for all outcome variables with repeated-measures models. Additional post hoc multiple regression analyses were carried out to investigate whether several objective factors (i.e., demographics and time under social restrictions) and carer-reported symptom changes observed following lockdown before T0 were associated with all outcomes at T0.

RESULTS

No significant changes were observed in any outcomes over the 6 months of observations. However, post hoc analyses showed that the length of social isolation before T0 was negatively correlated with episodic and semantic memory performance at T0. Carers reporting worsening of neuropsychiatric symptoms and faster disease progression in PWD also reported higher burden. Moreover, carer-reported worsening of cognitive symptoms was associated with poorer semantic memory at T0.

CONCLUSION

PWD's symptoms and carers' burden remained stable over 6 months of observation. However, the amount of time spent under social restrictions before T0 appears to have had a significant detrimental impact on cognitive performance of patients. In fact, carer-reported cognitive decline during social isolation was consistent with the finding of poorer semantic memory, a domain sensitive to progression in Alzheimer's disease. Therefore, the initial stricter period of social isolation had greater detrimental impact on patients and their carers, followed then by a plateau. Future interventions may be designed to maintain an optimal level of social and cognitive engagement for PWD in challenging times, to prevent abrupt worsening of symptoms and associated detrimental consequences on patients' carers.