Cognitive impact of COVID-19: looking beyond the short term

Central and peripheral kynurenine pathway metabolites in COVID-19: Implications for neurological and immunological responses

Long-term symptoms such as pain, fatigue, and cognitive impairments are commonly observed in individuals affected by coronavirus disease 2019 (COVID-19). Metabolites of the kynurenine pathway have been proposed to account for cognitive impairment in COVID-19 patients. Here, cerebrospinal fluid (CSF) and plasma levels of kynurenine pathway metabolites in 53 COVID-19 patients and 12 non-inflammatory neurological disease controls in Sweden were measured with an ultra-performance liquid chromatography-tandem mass spectrometry system (UPLC-MS/MS) and correlated with immunological markers and neurological markers. Single cell transcriptomic data from a previous study of 130 COVID-19 patients was used to investigate the expression of key genes in the kynurenine pathway. The present study reveals that the neuroactive kynurenine pathway metabolites quinolinic acid (QUIN) and kynurenic acid (KYNA) are increased in CSF in patients with acute COVID-19. In addition, CSF levels of kynurenine, ratio of kynurenine/tryptophan (rKT) and QUIN correlate with neurodegenerative markers. Furthermore, tryptophan is significantly decreased in plasma but not in the CSF. In addition, the kynurenine pathway is strongly activated in the plasma and correlates with the peripheral immunological marker neopterin. Single-cell transcriptomics revealed upregulated gene expressions of the rate-limiting enzyme indoleamine 2,3- dioxygenase1 (IDO1) in CD14+ and CD16+ monocytes that correlated with type II-interferon response exclusively in COVID-19 patients. In summary, our study confirms significant activation of the peripheral kynurenine pathway in patients with acute COVID-19 and, notably, this is the first study to identify elevated levels of kynurenine metabolites in the central nervous system associated with the disease. Our findings suggest that peripheral inflammation, potentially linked to overexpression of IDO1 in monocytes, activates the kynurenine pathway. Increased plasma kynurenine, crossing the blood-brain barrier, serves as a source for elevated brain KYNA and neurotoxic QUIN. We conclude that blocking peripheral-to-central kynurenine transport could be a promising strategy to protect against neurotoxic effects of QUIN in COVID-19 patients.

Association of COVID-19 with acute and post-acute risk of multiple different complications and mortality in patients infected with omicron variant stratified by initial disease severity: a cohort study in Hong Kong

BACKGROUND

Few studies have attempted to use clinical and laboratory parameters to stratify COVID-19 patients with severe versus non-severe initial disease and evaluate age-specific differences in developing multiple different COVID-19-associated disease outcomes.

METHODS

A retrospective cohort included patients from the electronic health database of Hong Kong Hospital Authority between 1 January 2022 and 15 August 2022 until 15 November 2022. The cohort was divided into three cohorts by age (≤ 40, 41-64, and ≥ 65 years old). Each age cohort was stratified into four groups: (1) COVID-19 critically exposed group (ICU admission, mechanical ventilation support, CRP > 80 mg/L, or D-dimer > 2 g/mL), (2) severely exposed group (CRP 30-80 mg/L, D-dimer 0.5-2 g/mL, or CT value < 20), (3) mildly-moderately exposed group (COVID-19 positive-tested but not fulfilling the criteria for the aforementioned critically and severely exposed groups), and (4) unexposed group (without COVID-19). The characteristics between groups were adjusted with propensity score-based marginal mean weighting through stratification. Cox regression was conducted to determine the association of COVID-19 disease severity with disease outcomes and mortality in the acute and post-acute phase (< 30 and ≥ 30 days from COVID-19 infection) in each age group.

RESULTS

A total of 286,114, 320,304 and 194,227 patients with mild-moderate COVID-19 infection; 18,419, 23,678 and 31,505 patients with severe COVID-19 infection; 1,168, 2,261 and 10,178 patients with critical COVID-19 infection, and 1,143,510, 1,369,365 and 1,012,177 uninfected people were identified in aged ≤ 40, 40-64, and ≥ 65 groups, respectively. Compared to the unexposed group, a general trend tending towards an increase in risks of multiple different disease outcomes as COVID-19 disease severity increases, with advancing age, was identified in both the acute and post-acute phases. Notably, the mildly-moderately exposed group were associated with either insignificant risks (aged ≤ 40) or the lowest risks (aged > 40) for the disease outcomes in the acute phase of infection (e.g., mortality risk HR (aged ≤ 40): 1.0 (95%CI: 0.5,2.0), HR (aged 41-64): 2.1 (95%CI: 1.8, 2.6), HR (aged > 65): 4.8 (95%CI: 4.6, 5.1)); while in the post-acute phase, these risks were largely insignificant in those aged < 65, remaining significant only in the elderly (age ≥ 65) (e.g., mortality risk HR (aged ≤ 40): 0.8 (95%CI: (0.5, 1.0)), HR (aged 41-64): 1.1 (95%CI: 1.0,1.2), HR (aged > 65): 1.5 (95%CI: 1.5,1.6)). Fully vaccinated patients were associated with lower risks of disease outcomes than those receiving less than two doses of vaccination.

CONCLUSIONS

The risk of multiple different disease outcomes in both acute and post-acute phases increased significantly with the increasing severity of acute COVID-19 illness, specifically among the elderly. Moreover, future studies could improve by risk-stratifying patients based on universally accepted thresholds for clinical parameters, particularly biomarkers, using biological evidence from immunological studies.

SARS-CoV-2 Spike Protein Exacerbates Thromboembolic Cerebrovascular Complications in Humanized ACE2 Mouse Model

COVID-19 increases the risk for acute ischemic stroke, yet the molecular mechanisms are unclear and remain unresolved medical challenges. We hypothesize that the SARS-CoV-2 spike protein exacerbates stroke and cerebrovascular complications by increasing coagulation and decreasing fibrinolysis by disrupting the renin-angiotensin-aldosterone system (RAAS). A thromboembolic model was induced in humanized ACE2 knock-in mice after one week of SARS-CoV-2 spike protein injection. hACE2 mice were treated with Losartan, an angiotensin receptor (AT1R) blocker, immediately after spike protein injection. Cerebral blood flow and infarct size were compared between groups. Vascular-contributes to cognitive impairments and dementia was assessed using a Novel object recognition test. Tissue factor-III and plasminogen activator inhibitor-1 were measured using immunoblotting to assess coagulation and fibrinolysis. Human brain microvascular endothelial cells (HBMEC) were exposed to hypoxia with/without SARS-CoV-2 spike protein to mimic ischemic conditions and assessed for inflammation, RAAS balance, coagulation, and fibrinolysis. Our results showed that the SARS-CoV-2 spike protein caused an imbalance in the RAAS that increased the inflammatory signal and decreased the RAAS protective arm. SARS-CoV-2 spike protein increased coagulation and decreased fibrinolysis when coincident with ischemic insult, which was accompanied by a decrease in cerebral blood flow, an increase in neuronal death, and a decline in cognitive function. Losartan treatment restored RAAS balance and reduced spike protein-induced effects. SARS-CoV-2 spike protein exacerbates inflammation and hypercoagulation, leading to increased neurovascular damage and cognitive dysfunction. However, the AT1R blocker, Losartan, restored the RAAS balance and reduced COVID-19-induced thromboembolic cerebrovascular complications.

Dissociable effects of mild COVID-19 on short- and long-term memories

Recent studies have highlighted the presence of cognitive deficits following COVID-19 that persist beyond acute infection, regardless of the initial disease severity. Impairments in short- and long-term memory are among the core deficits reported by patients and observed in objective tests of memory performance. We aimed to extend previous studies by examining performance in a task that allows us to directly compare and contrast memories at different timescales. More specifically, we assessed both short- and long-term memories for contextual-spatial associations encoded during a common session and probed at different durations using an equivalent task in non-hospitalized individuals recovering from mild COVID-19 compared to healthy controls. The approach equated all aspects of memory materials and response demands, isolating performance changes resulting only from memory timescales and thus allowing us to quantify the impact of COVID-19 on cognition. In addition to providing measures of accuracy and response times, the task also provided a sensitive continuous readout of the precision of memory representations, specifically by examining the resolution with which spatial locations were retained in memory. The results demonstrated selective impairment of long-term memory performance in individuals recovering from mild COVID-19 infection. Short-term memory performance remained comparable to healthy controls. Specifically, poor precision of long-term memory representations was demonstrated, which improved with days since diagnosis. No such relationship was observed for short-term memory performance. Our findings reveal a specific impairment to the precision of spatial-contextual long-term memory representations in individuals recovering from mild COVID-19 and demonstrate evidence of recovery in long-term memory over time. Further, the experimental design provides a carefully controlled and sensitive framework to assess memory across different durations with the potential to provide more detailed phenotyping of memory deficits associated with COVID-19 in general.

Exploring Neurocognitive and Emotional Outcomes of Long COVID: A Study Among Pakistani Patients

Background and objective Coronavirus disease 2019 (COVID-19), primarily a respiratory illness, also significantly impacts neurocognitive and emotional health, particularly in its long-term manifestation known as long COVID. This study aimed to investigate the neurocognitive and emotional outcomes of long-term COVID-19 in Pakistani patients, to address the persisting symptoms and their effects on mental health and cognitive function. Methods A cross-sectional study involving 100 adult participants who had been COVID-19-free was conducted in Islamabad between March 2022 and March 2023. Participants were assessed using the Mini-Mental State Examination (MMSE), attention-deficit/hyperactivity disorder (ADHD) Self-Report Questionnaire, Satisfaction with Life Scale (SWLS), and Punishing Allah Reappraisal Scale. Data were analyzed using SPSS Statistics v26 (IBM Corp., Armonk, NY), employing chi-square tests, t-tests, and ANOVA. Results The study revealed significant correlations between COVID-19 symptoms and psychological variables. COVID-19 symptoms showed a negative correlation with MMSE scores (r = -0.04, p<0.01) and positive correlations with ADHD (r = 0.13, p<0.05), depression (r = 0.14, p<0.05), and anxiety (r = 0.25, p<0.05). Females reported higher levels of depression [mean: 1.21, standard deviation (SD): 0.83] and anxiety (mean: 1.33, SD: 0.86) compared to males. Conclusions Our findings highlight the extensive impact of long-term COVID-19 on neurocognitive and emotional health, with significant gender differences observed in emotional outcomes. These results emphasize the need for integrated mental health services in post-COVID-19 care plans, as well as gender-sensitive interventions.

Memory alterations after COVID-19 infection: a systematic review

SARS-CoV-2 infection has a wide range of both acute and long-term symptoms. Memory alterations have been frequently reported in studies that explore cognition. The main objective of the systematic review is to update and further analyze the existing evidence of objective memory impairments in long-COVID-19 considering sample and study design characteristics, as well as to explore associations between memory performance and their epidemiological, clinical, and pathological features. A total of 13 studies were identified by searching in PubMed, Web of Science, and PsycInfo databases up to May 6, 2022. Most studies evaluated verbal component of memory in the short-term and long-term recall up to 30 min and mainly performed a single assessment completed at 4-6 months after the infection. The samples mainly consisted of middle-aged adults that required hospitalization. Samples were not stratified by sex, age, and severity. Poor verbal learning was reported in most cases (6-58%), followed by deficits in long-term (4-58%) and short-term (4-37%) verbal memory. Visuospatial component of memory was studied less than verbal component, showing impairment of long-term retention of visual items (10-49%). COVID-19 severity in the acute stage was not systematically associated with poor memory performance. Verbal memory deficits were associated with anxiety and depression. The existing literature on objective memory assessment in long-COVID suggests further research is warranted to confirm memory dysfunction in association with epidemiological, pathological, and clinical factors, using both verbal and visuospatial tests, and exploring in deep long-term memory deficits.

Neuropsychological Rehabilitation Improves Memory and Action Naming in Patients With Post-COVID-19 Syndrome

PURPOSE

Post-COVID-19 syndrome (PCS-19) is a condition characterized by both physical and cognitive alterations in patients who have overcome COVID-19. Despite the high incidence of this disorder and the inconveniences it produces to those affected, there are few studies investigating the efficacy of cognitive stimulation in these patients. The aim of this study was to compare two groups of patients with PCS-19. One of them was treated with neuropsychological intervention for 6 months, whereas the other did not receive treatment. Both groups shared similar clinical characteristics and cognitive profiles.

METHOD

The study included 15 participants. Eight (seven women and one man, with a mean age of 50.13 years) made up the experimental group and received neuropsychological rehabilitation sessions once a week with the aim of recovering or compensating for their impaired functions. The control group consisted of seven patients (six women and one man, with a mean age of 52.86 years) who did not undergo neuropsychological rehabilitation sessions. The neuropsychological assessment protocol included tests for all cognitive domains.

RESULTS

In comparison with the assessment prior to the neuropsychological intervention, significant differences were found in the experimental group both in verbal memory and in the action naming task. As for the control group, improvements in action fluency performance were observed. Neither group showed significant improvement in pre- versus posttest Stroop scores. However, the control group did perform higher than the treatment group in the final assessment.

CONCLUSION

Despite the small sample size, our results suggest that patients with PCS-19 may benefit from neuropsychological rehabilitation, as it may help them to improve several cognitive functions that do not recover spontaneously.

Extracellular Vesicles: The Invisible Heroes and Villains of COVID-19 Central Neuropathology

Acknowledging the neurological symptoms of COVID-19 and the long-lasting neurological damage even after the epidemic ends are common, necessitating ongoing vigilance. Initial investigations suggest that extracellular vesicles (EVs), which assist in the evasion of the host's immune response and achieve immune evasion in SARS-CoV-2 systemic spreading, contribute to the virus's attack on the central nervous system (CNS). The pro-inflammatory, pro-coagulant, and immunomodulatory properties of EVs contents may directly drive neuroinflammation and cerebral thrombosis in COVID-19. Additionally, EVs have attracted attention as potential candidates for targeted therapy in COVID-19 due to their innate homing properties, low immunogenicity, and ability to cross the blood-brain barrier (BBB) freely. Mesenchymal stromal/stem cell (MSCs) secreted EVs are widely applied and evaluated in patients with COVID-19 for their therapeutic effect, considering the limited antiviral treatment. This review summarizes the involvement of EVs in COVID-19 neuropathology as carriers of SARS-CoV-2 or other pathogenic contents, as predictors of COVID-19 neuropathology by transporting brain-derived substances, and as therapeutic agents by delivering biotherapeutic substances or drugs. Understanding the diverse roles of EVs in the neuropathological aspects of COVID-19 provides a comprehensive framework for developing, treating, and preventing central neuropathology and the severe consequences associated with the disease.

SARS-CoV-2 Infection Impairs Oculomotor Functions: A Longitudinal Eye-tracking Study

Although Severe Acute Respiratory Syndrome Coronavirus 2 infection (SARS-CoV-2) is primarily recognized as a respiratory disease, mounting evidence suggests that it may lead to neurological and cognitive impairments. The current study used three eye-tracking tasks (free-viewing, fixation, and smooth pursuit) to assess the oculomotor functions of mild infected cases over six months with symptomatic SARS-CoV-2 infected volunteers. Fifty symptomatic SARS-CoV-2 infected, and 24 self-reported healthy controls completed the eye-tracking tasks in an initial assessment. Then, 45, and 40 symptomatic SARS-CoV-2 infected completed the tasks at 2- and 6-months post-infection, respectively. In the initial assessment, symptomatic SARS-CoV-2 infected exhibited impairments in diverse eye movement metrics. Over the six months following infection, the infected reported overall improvement in health condition, except for self-perceived mental health. The eye movement patterns in the free-viewing task shifted toward a more focal processing mode and there was no significant improvement in fixation stability among the infected. A linear discriminant analysis shows that eye movement metrics could differentiate the infected from healthy controls with an accuracy of approximately 62%, even 6 months post-infection. These findings suggest that symptomatic SARSCoV- 2 infection may result in persistent impairments in oculomotor functions, and the employment of eye-tracking technology can offer valuable insights into both the immediate and long-term effects of SARS-CoV-2 infections. Future studies should employ a more balanced research design and leverage advanced machine-learning methods to comprehensively investigate the impact of SARSCoV- 2 infection on oculomotor functions.

Therapeutic potential and possible mechanisms of ginseng for depression associated with COVID-19

Recently, a global outbreak of COVID-19 has rapidly spread to various national regions. As the number of COVID-19 patients has increased, some of those infected with SARS-CoV-2 have developed a variety of psychiatric symptoms, including depression, cognitive impairment, and fatigue. A distinct storm of inflammatory factors that contribute to the initial disease but also a persistent post-acute phase syndrome has been reported in patients with COVID-19. Neuropsychological symptoms including depression, cognitive impairment, and fatigue are closely related to circulating and local (brain) inflammatory factors. Natural products are currently being examined for their ability to treat numerous complications caused by COVID-19. Among them, ginseng has anti-inflammatory, immune system stimulating, neuroendocrine modulating, and other effects, which may help improve psychiatric symptoms. This review summarizes the basic mechanisms of COVID-19 pneumonia, psychiatric symptoms following coronavirus infections, effects of ginseng on depression, restlessness, and other psychiatric symptoms associated with post-COVID syn-dromes, as well as possible mechanisms underlying these effects.

Unravelling the connection between COVID-19 and Alzheimer's disease: a comprehensive review

Currently, there exists a limited comprehension regarding the correlation between COVID-19 and Alzheimer's disease (AD). To elucidate the interrelationship and its impact on outcomes, a comprehensive investigation was carried out utilising time-unrestricted searches of reputable databases such as Scopus, PubMed, Web of Science, and Google Scholar. Our objective was to evaluate the impact of various medical conditions on severe COVID-19-related events. We focused on identifying and analysing articles that discussed the clinical characteristics of COVID-19 patients, particularly those pertaining to severe events such as ICU admission, mechanical ventilation, pneumonia, mortality and acute respiratory distress syndrome (ARDS) a serious lung condition that causes low blood oxygen. Through careful data analysis and information gathering, we tried to figure out how likely it was that people with conditions, like AD, would have serious events. Our research investigated potential mechanisms that link AD and COVID-19. The ability of the virus to directly invade the central nervous system and the role of ACE-2 receptors were investigated. Furthermore, the OAS1 gene served as the genetic link between AD and COVID-19. In the context of COVID-19, our findings suggest that individuals with AD may be more susceptible to experiencing severe outcomes. Consequently, it is crucial to provide personalised care and management for this demographic. Further investigation is required to attain a comprehensive comprehension of the intricate correlation between Alzheimer's disease and COVID-19, as well as its ramifications for patient outcomes.

Exploring the relationship of cognitive function with and without COVID-19 recovered schizophrenic patients

Background

The Coronavirus disease 2019 (COVID-19) is linked to the deterioration of cognitive function among individuals suffering from schizophrenia. The purpose of this study was to compare the cognitive performance of schizophrenic patients before and after COVID-19.

Methods

A longitudinal cohort study involving a sample of 219 individuals diagnosed with schizophrenia was enrolled between June 2022 and May 2023. The participants were split into two groups infected with COVID-19 (n = 165) and not infected with COVID-19 (n = 54). The data were gathered via a questionnaire on demographic characteristics, the Brief Assessment of Cognition in Schizophrenia (BACS), the Positive and Negative Syndrome Scale (PANSS), the Calgary Depression Scale for Schizophrenia (CDSS), the Activities of Daily Living (ADL) scale, and the Insomnia Severity Index (ISI).

Results

The repeated-measures ANOVA showed that Among patients diagnosed with COVID-19, there was a deterioration in global cognitive function (before COVID-19 = -2.45 vs. after COVID-19 = -3.02, p = 0.007), working memory (before COVID-19 = -2.76 vs. after COVID-19 = -3.34, p < 0.00 1), motor speed (before COVID-19 = -1.64 vs. after COVID-19 = -2.12, p < 0.001), attention and speed of information processing (before COVID-19 = -1.93 vs. after COVID-19 = -1.16, p = 0.008). multi-variable analysis showed that several factors as having a secondary grade of education (β = 0.434), experiencing insomnia (β = 0.411)and the interaction between COVID-19 diagnosis and cognition at baseline (β = 0.796) were significantly associated with cognitive deficits. At the same time, no significant associations were found between global cognition and clinical symptoms, autonomy, or depression (p > 0.05).

Conclusion

The COVID-19 pandemic has significantly impacted various cognitive functions, such as verbal memory, working memory, and global cognition. Insomnia has been identified as the predominant determinant of cognitive impairment, alongside the confirmation of a COVID-19 diagnosis. Additional research is imperative to elucidate the diversification of cognitive functionality observed in individuals diagnosed with schizophrenia who have acquired COVID-19.

Highlighting the Neuropsychological Consequences of COVID-19: Evidence From a Narrative Review

The coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus-2, although largely affecting the respiratory system, commonly presents with numerous clinical symptoms from other systems. COVID-19 has been associated with both acute and persistent neurological abnormalities in a substantial proportion of patients. Notably, post-COVID-19 neuropsychological abnormalities have garnered attention, highlighting a high prevalence of neurocognitive issues in affected individuals. This narrative review synthesizes current knowledge on the neuropsychological impact of COVID-19, drawing insights from an extensive online search of published literature conducted in the PubMed (MEDLINE) and Scopus databases. The findings underscore significant neuropsychological effects of COVID-19 observed at both individual and societal levels during the ongoing pandemic. Neuropsychological deficits such as memory difficulties, attention problems, and executive dysfunction, alongside physical symptoms like headaches and fatigue were commonly reported. Additionally, psychological challenges, including fear, anxiety, and depression, emerged as prevalent issues arising from the uncertainties surrounding the situation, social isolation, and employment insecurities. The identified neuropsychological manifestations of COVID-19 can significantly impede normal cognitive and emotional functioning, potentially resulting in decreased productivity and an overall decline in mental health and quality of life. Early identification of signs indicative of neurological or psychological decline becomes imperative, offering a crucial opportunity to mitigate the risk of long-term neuropsychological dysfunction through the development of targeted interventions.

Neuropsychological, plasma marker, and functional connectivity changes in Alzheimer's disease patients infected with COVID-19

Introduction

Patients with COVID-19 may experience various neurological conditions, including cognitive impairment, encephalitis, and stroke. This is particularly significant in individuals who already have Alzheimer's disease (AD), as the cognitive impairments can be more pronounced in these cases. However, the extent and underlying mechanisms of cognitive impairments in COVID-19-infected AD patients have yet to be fully investigated through clinical and neurophysiological approaches.

Methods

This study included a total of 77 AD patients. Cognitive functions were assessed using neuropsychiatric scales for all participants, and plasma biomarkers of amyloid protein and tau protein were measured in a subset of 25 participants. To investigate the changes in functional brain connectivity induced by COVID-19 infection, a cross-sectional neuroimaging design was conducted involving a subset of 37 AD patients, including a control group of 18 AD participants without COVID-19 infection and a COVID-19 group consisting of 19 AD participants.

Results

For the 77 AD patients between the stages of pre and post COVID-19 infection, there were significant differences in cognitive function and psychobehavioral symptoms on the Montreal Scale (MoCA), the neuropsychiatric inventory (NPI), the clinician's global impression of change (CIBIC-Plus), and the activity of daily living scale (ADL). The COVID-19 infection significantly decreased the plasma biomarker level of Aβ42 and increased the plasma p-tau181 level in AD patients. The COVID-19-infected AD patients show decreased local coherence (LCOR) in the anterior middle temporal gyrus and decreased global correlation (GCOR) in the precuneus and the medial prefrontal cortex.

Conclusion

The findings suggest clinical, cognitive, and neural alterations following COVID-19 infection in AD patients and emphasize the need for close monitoring of symptoms in AD patients who have had COVID-19 and further exploration of the underlying mechanisms.

Effect of oxygen therapy duration on cognitive impairment 12 months after hospitalization for SARS-COV-2 infection

OBJECTIVE

To identify predictors of persistent cognitive impairment at 12 months after hospitalization due to COVID-19 (SARS-CoV-2) infection.

DESIGN

Retrospective, single-centre study.

SUBJECTS

All consecutive patients assessed in physical and rehabilitation medicine consultations at 3 months with a neuropsychiatric testing (NPT) at 6 months.

METHODS

A Mini Mental State Examination (MMSE) was performed at 3 months and NPT at 6 and 12 months, exploring global cognitive efficiency, attention and processing speed, short-term memory and executive function. Logistic regression and receiver operating characteristic curves were used to identify predictors of persistent cognitive impairment.

RESULTS

Among 56 patients, 64.3% and 53.6% had 1 or more impaired cognitive functions at 6 and 12 months, respectively, attention and processing speed being the most represented (41.1% at 12 month). Duration of oxygen therapy (odds ratio 0.926 [0.871-0.985], p = 0.015) and MMSE score at 3 months (odds ratio 0.464 [0.276-0.783], p = 0.004) were associated with cognitive impairment at 12 months by multivariable analysis (R² 0.372-0.497).

CONCLUSIONS

Half of patients have cognitive impairment 12 months after acute SARS-CoV-2 infection requiring hospitalization. The duration of oxygen therapy in acute care could be a protective parameter. Systematic evaluation with the MMSE at 3 months after infection might be an effective tool to detect risk.

COVID-19 and Alzheimer's Disease Share Common Neurological and Ophthalmological Manifestations: A Bidirectional Risk in the Post-Pandemic Future

A growing body of evidence indicates that a neuropathological cross-talk takes place between the coronavirus disease 2019 (COVID-19) -the pandemic severe pneumonia that has had a tremendous impact on the global economy and health since three years after its outbreak in December 2019- and Alzheimer's Disease (AD), the leading cause of dementia among human beings, reaching 139 million by the year 2050. Even though COVID-19 is a primary respiratory disease, its causative agent, the so-called Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2), is also endowed with high neuro-invasive potential (Neurocovid). The neurological complications of COVID-19, resulting from the direct viral entry into the Central Nervous System (CNS) and/or indirect systemic inflammation and dysregulated activation of immune response, encompass memory decline and anosmia which are typically associated with AD symptomatology. In addition, patients diagnosed with AD are more vulnerable to SARS-CoV-2 infection and are inclined to more severe clinical outcomes. In the present review, we better elucidate the intimate connection between COVID-19 and AD by summarizing the involved risk factors/targets and the underlying biological mechanisms shared by these two disorders with a particular focus on the Angiotensin-Converting Enzyme 2 (ACE2) receptor, APOlipoprotein E (APOE), aging, neuroinflammation and cellular pathways associated with the Amyloid Precursor Protein (APP)/Amyloid beta (Aβ) and tau neuropathologies. Finally, the involvement of ophthalmological manifestations, including vitreo-retinal abnormalities and visual deficits, in both COVID-19 and AD are also discussed. Understanding the common physiopathological aspects linking COVID-19 and AD will pave the way to novel management and diagnostic/therapeutic approaches to cope with them in the post-pandemic future.

[Cognitive alterations in patients recovered from COVID-19 treated in Cardiopulmonary Rehabilitation]

Background

COVID-19 is associated with multiple complications, in addition to those produced at the pulmonary level. Post-COVID-19 cognitive deficits have been detected in the cognitive domain of attention and executive functions, even 4 months after COVID-19.

Objective

to determine the frequency of cognitive alterations in patients recovered from COVID-19.

Material and methods

A cross-sectional, descriptive and analytical study was carried out. Records of patients in care after infection by SARS-CoV-2 were integrated, the Neuropsi test was applied. Descriptive statistics and association tests were used through the Chi square test, taking p < 0.05 as significant.

Results

Data from 44 files were integrated. The median age, I place them in the sixth decade of life. There was a predominance of men (63.6%). The most frequent comorbidities were systemic arterial hypertension (50%) and diabetes mellitus (40.9%). Most of the patients were managed only at home (61.4%) with a moderate-severe COVID-19 picture (68.2%). The most affected dimensions of the Neuropsi test were attention and concentration (47.7%, mild alteration) and short-term memory (77.3%, mild alteration).

Conclusions

Cognitive impairment in patients recovered from COVID-19 assessed through the Neuropsi test presented mild alterations in attention and concentration, as well as in short-term memory. These could affect functionality, quality of life and ability to perform work.

Evidence from a meta-analysis and systematic review reveals the global prevalence of mild cognitive impairment

Objective

Mild cognitive impairment (MCI) is a preclinical and transitional stage between healthy ageing and dementia. The purpose of our study was to investigate the recent pooled global prevalence of MCI.

Methods

This meta-analysis was in line with the recommendations of Cochrane's Handbook and Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020. We conducted a comprehensive search using the PubMed, Embase, Web of Science, CNKI, WFD, VIP, and CBM from their inception to March 1, 2023. Quality assessment was guided by the Agency for Healthcare Research and Quality (AHRQ) methodology checklist. The pooled global prevalence of MCI was synthesized using meta-analysis via random effect model. Subgroup analyses were performed to examine considered factors potentially associated with MCI prevalence.

Results

We identified 233 studies involving 676,974 individuals aged above 50 years. All the studies rated as moderated-to-high quality. The overall prevalence of MCI was 19.7% [95% confidence interval (95% CI): 18.3-21.1%]. Subgroup analyses revealed that the global prevalence of MCI increased over time, with a significant rise [32.1% (95% CI: 22.6-41.6%)] after 2019. Additionally, MCI prevalence in hospitals [34.0% (95% CI: 22.2-45.7%)] was higher than in nursing homes [22.6% (95% CI: 15.5-29.8%)] and communities [17.9% (95% CI: 16.6-19.2%)], particularly after the epidemic of coronavirus disease 2019 (COVID-19).

Conclusion

The global prevalence of MCI was 19.7% and mainly correlated with beginning year of survey and sample source. The MCI prevalence increased largely in hospitals after 2019 may be related to the outbreak of COVID-19. Further attention to MCI is necessary in the future to inform allocation of health resources for at-risk populations.

Higher angiotensin-converting enzyme 2 (ACE2) levels in the brain of individuals with Alzheimer's disease

Cognitive decline due to Alzheimer's disease (AD) is frequent in the geriatric population, which has been disproportionately affected by the COVID-19 pandemic. In this study, we investigated the levels of angiotensin-converting enzyme 2 (ACE2), a regulator of the renin-angiotensin system and the main entry receptor of SARS-CoV-2 in host cells, in postmortem parietal cortex samples from two independent AD cohorts, totalling 142 persons. Higher concentrations of ACE2 protein (p < 0.01) and mRNA (p < 0.01) were found in individuals with a neuropathological diagnosis of AD compared to age-matched healthy control subjects. Brain levels of soluble ACE2 were inversely associated with cognitive scores (p = 0.02) and markers of pericytes (PDGFRβ, p = 0.02 and ANPEP, p = 0.007), but positively correlated with concentrations of soluble amyloid-β peptides (Aβ) (p = 0.01) and insoluble phospho-tau (S396/404, p = 0.002). However, no significant differences in ACE2 were observed in the 3xTg-AD mouse model of tau and Aβ neuropathology. Results from immunofluorescence and Western blots showed that ACE2 protein is predominantly localized in microvessels in the mouse brain whereas it is more frequently found in neurons in the human brain. The present data suggest that higher levels of soluble ACE2 in the human brain may contribute to AD, but their role in CNS infection by SARS-CoV-2 remains unclear.

Long-Term Headache and Cognitive Complaints Among Health Care Workers Who Acquired SARS-CoV-2

Introduction Neurological manifestations are frequent after acquiring COVID-19 and may persist long-term as part of post-COVID-19 syndrome. Cognitive impairment, chronic fatigue, sleep disturbances, and headache complaints are the most reported neurological features. During the COVID-19 pandemic, health care workers were particularly vulnerable due to the high workload and levels of stress associated with this period, but acquiring severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) may also contribute. The authors aimed to evaluate the neurological involvement of acquiring SARS-CoV-2 in a population of hospital health care workers and its impact on their personal and professional lives. Methods A sample of health care workers who did and did not acquire SARS-CoV-2 matched by age and sociodemographic variables was studied. Through an online questionnaire, data were collected regarding the symptoms in the acute phase of the disease (for those who acquired it) and for all in the last 6 months of the study period. Proportion of neurological complaints were compared between groups, adjusting for age, sex, and professional class (using a rate ratio (RR)). Results This study included 326 participants (174 cases and 152 controls). The mean age (standard deviation) was 39.7 (10.2) years, and the female:male ratio was 3:1. Headache and cognitive complaints were the most prevalent neurological complaints in the last 6 months of the study period. The health care workers who acquired SARS-CoV-2 were more likely to report headache and cognitive complaints than the control group (RR = 1.51, 95% confidence interval = 1.17-1.9 and RR = 2.02, 95% confidence interval = 1.53-2.65, respectively). Conclusion In a population of health care workers, those who acquired SARS-CoV-2 were more likely to have long-term cognitive complaints and persistent headaches.

Autoimmune encephalitis in COVID-19 patients: a systematic review of case reports and case series

Background

There is mounting evidence suggesting that autoimmune encephalitis (AE) can be observed as a neurological complication in patients with COVID-19. This review aimed to summarize the clinical manifestations, types, and outcomes of COVID-19-associated AE.

Methods

A systematic search was conducted in the PubMed, Embase, and Web of Science databases to identify case reports and case series related to COVID-19-associated AE from 1 January 2020 to 31 March 2023. After a thorough screening and evaluation, irrelevant articles were excluded. Relevant information concerning types, clinical manifestations, and outcomes was extracted and synthesized.

Results

A total of 37 studies, comprising 34 case reports and 3 case series, were included in this review. Among the 42 COVID-19-associated AE patients, 21 (50%) cases were classified as an unknown antibodies (Ab) type of COVID-19-associated AE, 10 (23.80%) cases as anti-N-methyl-D-aspartate (NMDA) encephalitis, 4 (9.5%) cases as limbic encephalitis, and 3 (7.1%) cases as anti-myelin-oligodendrocyte-glycoprotein encephalitis, along with other rare types of AE. Disturbance of consciousness, seizures, and psychiatric symptoms were identified as the main clinical manifestations of COVID-19-associated AE. While the symptoms of AE displayed variation, most patients achieved full recovery although a few experienced residual symptoms of neurological damage.

Conclusion

This systematic review comprehensively describes the characteristics of COVID-19-associated AE. The main type of COVID-19-associated AE identified in this study is an unknown Ab type of COVID-19-associated AE. Despite the potentially life-threatening risks of COVID-19-associated AE, the majority of patients survived, with some patients reporting residual neurological symptoms.

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

Purpose of review

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

Recent findings

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

Summary

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

Neuropsychological deficits in patients with persistent COVID-19 symptoms: a systematic review and meta-analysis

Long-term persistent symptoms of COVID-19 affect 30-80% of patients who have recovered from the disease and may continue for a long time after the disease has been overcome. The duration of these symptoms over time might have consequences that affect different aspects of health, such as cognitive abilities. The main objective of this systematic review and meta-analysis was to objectify the persistent COVID-19 cognitive deficits after acute phase of infection and to summarize the existing evidence. Additionally, we aimed to provide a comprehensive overview to further understand and address the consequences of this disease. Our protocol was registered in PROSPERO (CRD42021260286). Systematic research was conducted in the Web of Science, MEDLINE, PubMed, PsycINFO, Scopus, and Google Scholar databases from January 2020 to September 2021. Twenty-five studies were included, six of which were analyzed for the meta-analysis, and consisted of 175 patients who had recovered from COVID-19 and 275 healthy individuals. Analyses of cognitive performance of post-COVID-19 patients and healthy volunteers were compared using a random-effects model. The results showed an overall medium-high effect size (g = -.68, p = .02) with a 95% CI (-1.05 to -.31), with a significantly moderate level of heterogeneity among studies (Z = 3.58, p < .001; I2 = 63%). The results showed that individuals who had recovered from COVID-19 showed significant cognitive deficits compared to controls. Future studies should carefully assess the long-term progression of cognitive impairments in patients with persistent COVID-19 symptoms, as well as the effectiveness of rehabilitation interventions. Nevertheless, there is an urgent need to know the profile to speed up development of prevention plans as well as specific interventions. Since more information is being obtained and more studies are being conducted on the subject, the need to examine this symptomatology multidisciplinary to achieve greater scientific evidence of its incidence and prevalence has become increasingly clear.

A likely association between low mannan-binding lectin level and brain fog onset in long COVID patients

Brain fog can be described as a constellation of new-onset neuropsychiatric sequelae in the post-acute phase of COVID-19 (long COVID). The symptoms include inattention, short-term memory loss, and reduced mental acuity, which may undermine cognition, concentration, and sleep. This cognitive impairment, persisting for weeks or months after the acute phase of SARS-CoV-2 infection, can significantly impact on daily activities and the quality of life. An important role for the complement system (C) in the pathogenesis of COVID-19 has emerged since the beginning of pandemic outbreak. A number of pathophysiological characteristics including microangiopathy and myocarditis have been attributed to dysregulated C activation due to SARS-CoV-2 infection. Mannan-binding lectin (MBL), the first recognition subcomponent of the C lectin pathway, has been shown to bind to glycosylated SARS-CoV-2 spike protein, genetic variants of MBL2 are suggested to have an association with severe COVID-19 manifestations requiring hospitalization. In the present study, we evaluated MBL activity (lectin pathway activation) and levels in the sera of a cohort of COVID-19 patients, presenting brain fog or only hyposmia/hypogeusia as persistent symptoms, and compared them with healthy volunteers. We found significantly lower levels of MBL and lectin pathway activity in the sera of patients experiencing brain fog as compared to recovered COVID-19 patients without brain fog. Our data indicate that long COVID-associated brain fog can be listed among the variegate manifestations of increased susceptibility to infections and diseases contributed by MBL deficiency.

Externalizing traits: Shared causalities for COVID-19 and Alzheimer's dementia using Mendelian randomization analysis

Externalizing traits have been related with the outcomes of coronavirus disease 2019 (COVID-19) and Alzheimer's dementia (AD); however, whether these associations are causal remains unknown. We used the two-sample Mendelian randomization (MR) approach with more than 200 single-nucleotide polymorphisms (SNPs) for externalizing traits to explore the causal associations of externalizing traits with the risk of COVID-19 (infected COVID-19, hospitalized COVID-19, and severe COVID-19) or AD based on the summary data. The inverse variance-weighted method (IVW) was used to estimate the main effect, followed by several sensitivity analyses. IVW analysis showed significant associations of externalizing traits with COVID-19 infection (odds ratio [OR] = 1.456, 95% confidence interval [95% CI] = 1.224-1.731), hospitalized COVID-19 (OR = 1.970, 95% CI = 1.374-2.826), and AD (OR = 1.077, 95% CI = 1.037-1.119). The results were consistent using weighted median (WM), penalized weighted median (PWM), MR-robust adjusted profile score (MR-RAPS), and leave-one-out sensitivity analyses. Our findings assist in exploring the causal effect of externalizing traits on the pathophysiology of infection and severe infection of COVID-19 and AD. Furthermore, our study provides evidence that shared externalizing traits underpin the two diseases.

Multimodal neuroimaging in post-COVID syndrome and correlation with cognition

Brain changes have been reported in the first weeks after SARS-CoV-2 infection. However, limited literature exists about brain alterations in post-COVID syndrome, a condition increasingly associated with cognitive impairment. The present study aimed to evaluate brain functional and structural alterations in patients with post-COVID syndrome, and assess whether these brain alterations were related to cognitive dysfunction. Eighty-six patients with post-COVID syndrome and 36 healthy controls were recruited and underwent neuroimaging acquisition and a comprehensive neuropsychological assessment. Cognitive and neuroimaging examinations were performed 11 months after the first symptoms of SARS-CoV-2. Whole-brain functional connectivity analysis was performed. Voxel-based morphometry was performed to evaluate grey matter volume, and diffusion tensor imaging was carried out to analyse white-matter alterations. Correlations between cognition and brain changes were conducted and Bonferroni corrected. Post-COVID syndrome patients presented with functional connectivity changes, characterized by hypoconnectivity between left and right parahippocampal areas, and between bilateral orbitofrontal and cerebellar areas compared to controls. These alterations were accompanied by reduced grey matter volume in cortical, limbic and cerebellar areas, and alterations in white matter axial and mean diffusivity. Grey matter volume loss showed significant associations with cognitive dysfunction. These cognitive and brain alterations were more pronounced in hospitalized patients compared to non-hospitalized patients. No associations with vaccination status were found. The present study shows persistent structural and functional brain abnormalities 11 months after the acute infection. These changes are associated with cognitive dysfunction and contribute to a better understanding of the pathophysiology of the post-COVID syndrome.

Blood-brain barrier penetration of non-replicating SARS-CoV-2 and S1 variants of concern induce neuroinflammation which is accentuated in a mouse model of Alzheimer's disease

COVID-19 and especially Long COVID are associated with severe CNS symptoms and may place persons at risk to develop long-term cognitive impairments. Here, we show that two non-infective models of SARS-CoV-2 can cross the blood-brain barrier (BBB) and induce neuroinflammation, a major mechanism underpinning CNS and cognitive impairments, even in the absence of productive infection. The viral models cross the BBB by the mechanism of adsorptive transcytosis with the sugar N-acetylglucosamine being key. The delta and omicron variants cross the BB B faster than the other variants of concern, with peripheral tissue uptake rates also differing for the variants. Neuroinflammation induced by icv injection of S1 protein was greatly enhanced in young and especially in aged SAMP8 mice, a model of Alzheimer's disease, whereas sex and obesity had little effect.

COVID-19 Accelerated Cognitive Decline in Elderly Patients with Pre-Existing Dementia Followed up in an Outpatient Memory Care Facility

INTRODUCTION

Coronavirus disease 2019 (COVID-19) may affect the cognitive function and activities of daily living (ADL) of elderly patients. This study aimed to establish the COVID-19 effect on cognitive decline and the velocity of cognitive function and ADL changes in elderly patients with dementia followed up in an outpatient memory care facility.

METHODS

In total, 111 consecutive patients (age 82 ± 5 years, 32% males) with a baseline visit before infection were divided into those who had or did not have COVID-19. Cognitive decline was defined as a five-point loss of Mini-Mental State Examination (MMSE) score and ADL comprising basic and instrumental ADL indexes (BADL and IADL, respectively). COVID-19 effect on cognitive decline was weighted for confounding variables by the propensity score, whereas the effect on change in the MMSE score and ADL indexes was analyzed using multivariate mixed-effect linear regression.

RESULTS

COVID-19 occurred in 31 patients and a cognitive decline in 44. Cognitive decline was about three and a half times more frequent in patients who had COVID-19 (weighted hazard ratio 3.56, 95% confidence interval 1.50-8.59, p = 0.004). The MMSE score lowered on average by 1.7 points/year, independently of COVID-19, but it lowered twice faster in those who had COVID-19 (3.3 vs. 1.7 points/year, respectively, p < 0.050). BADL and IADL indexes lowered on average less than 1 point/year, independently of COVID-19 occurrence. Patients who had COVID-19 had a higher incidence of new institutionalization than those who did not have the disease (45% versus 20%, p = 0.016, respectively).

CONCLUSIONS

COVID-19 had a significant impact on cognitive decline and accelerated MMSE reduction in elderly patients with dementia.

Cognition in COVID-19 infected patients undergoing invasive ventilation: results from a multicenter retrospective study

A growing number of scientific contributions suggest that COVID-19 infection can lead to impairment of cognition, mainly in executive functions and memory domains, even in the absence of frank neurological pathologies.The primary objective of this retrospective study is to evaluate the frequency and type of inefficiencies in a selection of cognitive tests administered to a sample of subjects who, following infection, required invasive assisted ventilation and were admitted to rehabilitation wards for the treatment of functional impairment.Fifty-seven subjects were enrolled. The recruited patients undergone an assessment of verbal and visuospatial memory and executive functions, upon entry into the rehabilitation department, after discharge from intensive care. The following tests were administered: Rey Auditory Verbal Learning Test (AVLT) (immediate and delayed recall), Rey-Osterrieth Complex Figure Test (ROCFT) (copy and delayed recall), Stroop Color-Word Test, and Trail Making Test (TMT, A and B).Deficient scores, in beyond 25% of subjects, were found in the copy of the ROCFT (32.1% of subjects), and in the delayed recall of ROCFT (27.2%). Between 10 and 20% of patients presented an abnormal result in delayed recall of AVLT (16.07%), and Stroop Test (time, 15.6%, error, 11.5%). Less than 10% of the sample had abnormal performances on TMT (A, 3.5%, and B, 9.4%), and in AVLT immediate recall (8.9%). Correlations of the performances with age, sex, and education were also found.This paper highlights the high incidence of abnormal cognitive performances in this specific subpopulation of patients with COVID-19 infection.

Cognitive Complaints Assessment and Neuropsychiatric Disorders After Mild COVID-19 Infection

OBJECTIVES

This study aimed to analyze cognitive impairment associated with long-term coronavirus disease 2019 (COVID-19) syndrome and its correlation with anxiety, depression, and fatigue in patients infected with severe acute respiratory syndrome coronavirus.

METHODS

This was a cross-sectional study of 127 patients with COVID-19. Tests to screen for neuropsychiatric symptoms included the Fatigue Severity Scale, Mini-Mental State Exam 2 (MMSE-2), Symbol Digit Modalities Test (SDMT), and Hospital Anxiety and Depression Scale.

RESULTS

In cognitive tests, SDMT was abnormal in 22%, being more sensitive than MMSE-2 to detect cognitive changes. Furthermore, although manifestations such as fatigue, depression, and anxiety were frequent in the post-COVID-19 phase, these 3 conditions, known to contribute to cognitive impairment, were slightly correlated with worse performance on the rapid screening tests.

CONCLUSIONS

In patients with mild COVID-19 and cognitive complaints, SDMT helped to confirm disturbances in the attention domain and processing speed.

Role of Citicoline in Patients With Mild Cognitive Impairment

The term mild cognitive impairment (MCI) defines an intermediate state between normal aging and dementia. Vascular cognitive impairment refers to a decline in cognitive function that is caused by or associated with vascular disease and comprises all the spectrum of cognitive impairments, from MCI of vascular origin to vascular dementia. One of the available treatments for cognitive impairment is cytidine diphosphate-choline (CDP-Choline), or citicoline. The objective of the present manuscript is to provide complete evidence about the efficacy of citicoline for MCI, especially of vascular origin, but also due to other neurodegenerative disorders. Citicoline is a pharmaceutical product constituted by the combination of 2 natural molecules (cytidine and choline) and is marketed as a food supplement. It has been proposed to provide neuroprotective effects through diverse mechanisms of action. Taking into account the available literature, citicoline has shown a consistent improvement in cognitive function in patients with MCI, especially of vascular origin. Moreover, it provides beneficial effects on vascular, Alzheimer, and mixed dementias, stroke sequelae, intracerebral hemorrhages, traumatic brain injuries, and neurodegenerative diseases. Long-term treatment with citicoline has also been demonstrated to be well-tolerated and has not been associated with severe adverse events. Citicoline is a safe, well-tolerated, and promising agent with evidenced neuroprotective properties.

Post-COVID-19 Syndrome Comprehensive Assessment: From Clinical Diagnosis to Imaging and Biochemical-Guided Diagnosis and Management

The COVID-19 outbreak was first reported in 2019, causing massive morbidity and mortality. The majority of the COVID-19 patients survived and developed Post-COVID-19 Syndrome (PC19S) of varying severity. Currently, the diagnosis of PC19S is achieved through history and symptomatology that cannot be explained by an alternative diagnosis. However, the heavy reliance on subjective reporting is prone to reporting errors. Besides, there is no unified diagnostic assessment tool to classify the clinical severity of patients. This leads to significant difficulties when managing patients in terms of public resource utilization, clinical progression monitorization and rehabilitation plan formulation. This narrative review aims to review current evidence of diagnosis based on triple assessment: clinical symptomatology, biochemical analysis and imaging evidence. Further assessment tools can be developed based on triple assessment to monitor patient's clinical progression, prognosis and intervals of monitoring. It also highlights the high-risk features of patients for closer and earlier monitoring. Rehabilitation programs and related clinical trials are evaluated; however, most of them focus on cardiorespiratory fitness and psychiatric presentations such as anxiety and depression. Further research is required to establish an objective and comprehensive assessment tool to facilitate clinical management and rehabilitation plans.

The Effects of SARS-CoV-2 Infection on the Cognitive Functioning of Patients with Pre-Existing Dementia

Background

Cognitive postscripts of COVID-19, codenamed as 'cognitive COVID' or 'brain fog,' characterized by multidomain cognitive impairments, are now being reckoned as the most devastating sequelae of COVID-19. However, the impact on the already demented brain has not been studied.

Objective

We aimed to assess the cognitive functioning and neuroimaging following SARS-CoV-2 infection in patients with pre-existing dementia.

Methods

Fourteen COVID-19 survivors with pre-existing dementia (four with Alzheimer's disease, five with vascular dementia, three with Parkinson's disease dementia, and two with the behavioral variant of frontotemporal dementia) were recruited. All these patients had detailed cognitive and neuroimaging evaluations within three months before suffering from COVID-19 and one year later.

Results

Of the 14 patients, ten required hospitalization. All developed or increased white matter hyperintensities that mimicked multiple sclerosis and small vessel disease. There was a significant increase in fatigue (p = 0.001) and depression (p = 0.016) scores following COVID-19. The mean Frontal Assessment Battery (p < 0.001) and Addenbrooke's Cognitive Examination (p = 0.001) scores also significantly worsened.

Conclusion

The rapid progression of dementia, the addition of further impairments/deterioration of cognitive abilities, and the increase or new appearance of white matter lesion burden suggest that previously compromised brains have little defense to withstand a new insult (i.e., 'second hit' like infection/dysregulated immune response, and inflammation). 'Brain fog' is an ambiguous terminology without specific attribution to the spectrum of post-COVID-19 cognitive sequelae. We propose a new codename, i.e. 'FADE-IN MEMORY' (i.e., Fatigue, decreased Fluency, Attention deficit, Depression, Executive dysfunction, slowed INformation processing speed, and subcortical MEMORY impairment).

SARS-CoV-2 targets pericytes to restrict blood flow within the brain

This scientific commentary refers to ‘SARS-CoV-2 triggers pericyte-mediated cerebral capillary constriction’ by Hirunpattarasilp et al. (https://doi.org/10.1093/brain/awac272).

Cognitive deficit in post-acute COVID-19: an opportunity for EEG evaluation?

BACKGROUND AND PURPOSE

Among the most common post-COVID symptoms, many patients experienced subjective cognitive deficit, commonly named "brain fog," that might be present also in those individuals without severe acute COVID-19 respiratory involvement. Some studies have investigated some of the mechanisms that might be associated with the brain fog with objective techniques including transcranial magnetic stimulation and neuroimaging.

METHODS

The aim of this study was to investigate the presence of electroencephalographic (EEG) alterations in people with post-COVID self-reported cognitive deficit.

RESULTS

Out of the 90 patients attending the post-COVID neurology ambulatory service, twenty patients presenting brain fog at least 4 weeks after acute non-severe COVID-19 infection, and without previous history of epilepsy, were investigated with 19-channel EEG, Montreal Cognitive Assessment (MoCA), and magnetic resonance imaging (MRI). EEG was found altered in 65% of the sample, among which 69% presented a slowing activity and 31% were characterized by epileptic discharges principally in the frontal areas. None of the patients showed DWI MRI lesions.

CONCLUSIONS

These findings highlight the usefulness of EEG analysis to objectively describe possible neurophysiological abnormalities in post-COVID patients presenting subjective cognitive deficit.

COVID-19 infection does not seem to affect cognition in college students

Emerging evidence indicates that COVID-19 damages the central nervous system and thereby might engender long-term cognitive impairment. Self-reports and some measures of cognitive ability suggest that long COVID can lead to substantial and frightening detriments in cognition. To further explore this issue, we used data from university courses on cognitive psychology where students participated in classic experiments that measure various aspects of cognition. Across 24 experiments we compared cognitive performance of students who had contracted COVID-19 against those who were uninfected. Using Bayes Factor analyses, we assessed both differences and invariances in performance as a function of infection status. Our findings suggest that COVID-19 infection has hardly any impact on cognition for university students.

Higher Angiotensin I Converting Enzyme 2 (ACE2) levels in the brain of individuals with Alzheimer's disease

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a major cause of death in the elderly. Cognitive decline due to Alzheimer's disease (AD) is frequent in the geriatric population disproportionately affected by the COVID-19 pandemic. Interestingly, central nervous system (CNS) manifestations have been reported in SARS-CoV-2-infected patients. In this study, we investigated the levels of Angiotensin I Converting Enzyme 2 (ACE2), the main entry receptor of SARS-COV-2 in cells, in postmortem parietal cortex samples from two independent AD cohorts, totalling 142 persons. Higher concentrations of ACE2 protein and mRNA were found in individuals with a neuropathological diagnosis of AD compared to age-matched healthy control subjects. Brain levels of soluble ACE2 were inversely associated with cognitive scores (p = 0.02), markers of pericytes (PDGFRβ, p=0.02 and ANPEP, p = 0.007) and caveolin1 (p = 0.03), but positively correlated with soluble amyloid-β peptides (Aβ) concentrations (p = 0.01) and insoluble phospho- tau (S396/404, p = 0.002). No significant differences in ACE2 were observed in the 3xTgAD mouse model of tau and Aβ neuropathology. Results from immunofluorescence and Western blots showed that ACE2 protein is mainly localized in neurons in the human brain but predominantly in microvessels in the mouse brain. The present data show that an AD diagnosis is associated with higher levels of soluble ACE2 in the human brain, which might contribute to a higher risk of CNS SARS-CoV-2 infection.

Evaluation of cognitive functions in adult individuals with COVID-19

BACKGROUND AND PURPOSE

Cognitive deficits that are associated with coronavirus disease 2019 (COVID-19) and occur in the acute period are gaining importance. While most studies have focused on the elderly severely affected during acute infection, it remains unclear whether mild to moderate COVID-19 results in cognitive deficits in young patients. This study aims to evaluate the post-infection cognitive functions of young adults with mild to moderate symptoms of COVID-19.

METHODS

A total of 100 adults with similar age and educational background were included in the study. Half of those had been infected with COVID-19 in the last 60 days (N = 50), and the other half had not (N = 50). Global cognitive skills of the participants were evaluated through Montreal Cognitive Assessment Scale (MoCA) and Clock-Drawing Test; memory functions with Öktem Verbal Memory Processes Test (Ö-VMPT); attention span with Digit Span Test; executive functions with Fluency Tests, Stroop Test, and Trail Making Test; visual perceptual skills with Rey Osterrieth Complex Figure Test (ROCF); and neuropsychiatric status with Neuropsychiatric Inventory (NPI). Evaluations were performed in the experimental group for 21 to 60 days from the onset of the disease, and throughout the study, in the control group.

RESULTS

It was found that global cognitive skills, verbal memory, visual memory, executive function, and neuropsychiatric status were affected during COVID-19 (p < 0.05).

CONCLUSION

When the cases were analyzed according to disease severity, no relationship was found between cognitive deficits and disease severity.

Cognitive Deficits among Individuals Admitted to a Post-Acute Pneumological Rehabilitation Unit in Southern Italy after COVID-19 Infection

(1) Background: We investigated the differences in the neuropsychological profile as well as the pneumological and motor functions in two groups of patients admitted to rehabilitation who received different respiratory support during their COVID-19 infection. (2) Methods: Group-1 (n = 18; 15 male, median age 67.5) consisted of patients who received non-invasive mechanical ventilation; Group-2 (n = 19; 16 male, median age 63) consisted of patients who received invasive mechanical ventilation. All patients underwent a neuropsychological assessment including Mini-Mental State Examination (MMSE), Frontal Assessment Battery (FAB), and the Repeatable Battery for the Assessment of Neuropsychological Status (R-BANS) to evaluate the patients' cognition. Depression and anxiety were also measured at admission and discharge to rehabilitation. (3) Results: At admission, patients impaired at MMSE were 44% in Group-1 and 5% in Group-2, while patients impaired at FAB were 88% in Group-1 and 26% in Group-2. Wilcoxon's effect size revealed meaningful differences between groups for FAB, R-BANS global score, immediate and delayed memory, and attention-coding task, with Group-2 performing better than Group-1 across all measures. At discharge, 52% of the 25 patients re-assessed still had mild to moderate cognitive deficits, while 19% had depression and 35% had anxiety. (4) Conclusions: Patients who received oxygen therapy experienced higher levels of acute and chronic stress compared to those who benefitted from invasive mechanical ventilation. Despite patients showing a meaningful improvement at discharge, cognitive impairment persisted in a great number of patients; therefore, long-term neuropsychological follow-up and treatment for COVID-19 patients are recommended.

Cognitive and emotional impairments associated with COVID-19 (literature review)

Background. Currently, there are two main areas of study of the impact of a new coronavirus infection on mental processes: the first is in connection with the regime of self-isolation and restrictions in a pandemic; the second – with the impact of the pathological process itself and the post-covid syndrome on the central nervous system. The results of the studies indicate the relationship of this infection with local lesions of the brain and the corresponding disturbances in the functioning of mental processes.The aim of the research. To systematize and analyze the results of studies on the main routes of penetration of the SARS-CoV-2 virus into the central nervous system, cognitive and emotional disorders in people who have recovered from COVID-19, and to discuss the areas of psychological rehabilitation for this group of patients.Materials and methods. Information search was carried out using Internet resources (PubMed, Web of Science, Scopus, bmj.com, eLibrary.ru, frontiersin.org, sciencedirect. com, ncbi.nlm.nih.gov), literature sources were analyzed for the period from May of 2020 to November of 2021 for the following keywords: COVID-19, SARS-CoV-2, cognitive functions, cognitions, cognitive impairments, emotional dysfunction, affective dysfunction.Results. According to the analysis of the literature, most researchers identify the neurogenic pathway of SARS-CoV-2 penetration into the CNS, as well as penetration through the bloodstream or through cerebral lymphatic drainage, which are a possible cause of mental disorders of a neurological nature. Correction of these violations involves the creation of a comprehensive system of rehabilitation with the inclusion of psychotherapeutic methods.Conclusions. Despite the lack of a single picture describing the specifics of cognitive and affective symptoms in COVID-19, in the most general terms, there is a certain consensus. So, quite often, post-COVID cognitive symptoms are characterized by impaired memory and attention, and post-COVID affective symptoms are characterized by increased levels of anxiety, depression, and fatigue. The issues of diagnosis and correction of disorders in post-COVID syndrome and the admissibility of the existence of this diagnosis are still relevant.

Cognitive Impairment after Post-Acute COVID-19 Infection: A Systematic Review of the Literature

The present study aims to provide a critical overview of the literature on the relationships between post-acute COVID-19 infection and cognitive impairment, highlighting the limitations and confounding factors. A systematic search of articles published from 1 January 2020 to 1 July 2022 was performed in PubMed/Medline. We followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Only studies using validated instruments for the assessment of cognitive impairment were included. Out of 5515 screened records, 72 studies met the inclusion criteria. The available evidence revealed the presence of impairment in executive functions, speed of processing, attention and memory in subjects recovered from COVID-19. However, several limitations of the literature reviewed should be highlighted: most studies were performed on small samples, not stratified by severity of disease and age, used as a cross-sectional or a short-term longitudinal design and provided a limited assessment of the different cognitive domains. Few studies investigated the neurobiological correlates of cognitive deficits in individuals recovered from COVID-19. Further studies with an adequate methodological design are needed for an in-depth characterization of cognitive impairment in individuals recovered from COVID-19.

Direct, indirect, post-infection damages induced by coronavirus in the human body: an overview

Background

Severe acute respiratory syndrome Coronavirus-2 invades the cells via ACE2 receptor and damages multiple organs of the human body. Understanding the pathological manifestation is mandatory to endure the rising post-infection sequel reported in patients with or without comorbidities.

Materials and methods

Our descriptive review emphasises the direct, indirect and post-infection damages due to COVID-19. We have performed an electronic database search according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines with selective inclusion and exclusion criteria.

Results

The included studies substantiated the extensive damages in the multiple organs due to direct and indirect consequences of COVID-19. After an apparent recovery, the prolonged presentation of the symptoms manifests as post-COVID that can be related with persisting viral antigens and dysregulated immune response.

Conclusion

A few of the symptoms of respiratory, cardiovascular, and neuropsychiatric systems that persist or reappear as post-COVID manifestations. Vaccination and preventive programs will effectively reduce the prevalence but, the post-COVID, a multisystem manifestation, will be a significant tribulation to the medical profession. However, the issue can be managed by implementing public health programs, rehabilitation services, and telemedicine virtual supports to raise awareness and reduce panic.

Brain fog as a Long-term Sequela of COVID-19

Increasing data indicate that people infected with COVID-19 are at high risk for developing long-term neurological complications, such as "brain fog" or cognitive impairment. However, little is known about the long-term outcomes of COVID-19 survivors. This also applies to the prevalence, risk factors, and pathobiological findings associated with these consequences. Although cognitive complications are anticipated in patients who require a long-lasting hospital stay or intubation, milder cases of COVID-19 with no record of hospitalization have also been shown to experience assessable cognitive challenges. Cognitive impairment can have a devastating impact on daily functioning. Understanding the long-term effect of COVID-19 on cognitive function is vital for applying specific schemes to those who wish to return to their jobs productively.

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

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

Central hypersomnia and chronic insomnia: expanding the spectrum of sleep disorders in long COVID syndrome - a prospective cohort study

Introduction

Long-onset COVID syndrome has been described in patients with COVID-19 infection with persistence of symptoms or development of sequelae beyond 4 weeks after the onset of acute symptoms, a medium- and long-term consequence of COVID-19. This syndrome can affect up to 32% of affected individuals, with symptoms of fatigue, dyspnea, chest pain, cognitive disorders, insomnia, and psychiatric disorders. The present study aimed to characterize and evaluate the prevalence of sleep symptoms in patients with long COVID syndrome.

Methodology

A total of 207 patients with post-COVID symptoms were evaluated through clinical evaluation with a neurologist and specific exams in the subgroup complaining of excessive sleepiness.

Results

Among 189 patients included in the long COVID sample, 48 (25.3%) had sleep-related symptoms. Insomnia was reported by 42 patients (22.2%), and excessive sleepiness (ES) was reported by 6 patients (3.17%). Four patients with ES were evaluated with polysomnography and test, multiple sleep latencies test, and actigraphic data. Two patients had a diagnosis of central hypersomnia, and one had narcolepsy. A history of steroid use was related to sleep complaints (insomnia and excessive sleepiness), whereas depression was related to excessive sleepiness. We observed a high prevalence of cognitive complaints in these patients.

Conclusion

Complaints related to sleep, such as insomnia and excessive sleepiness, seem to be part of the clinical post-acute syndrome (long COVID syndrome), composing part of its clinical spectrum, relating to some clinical data.

Environmental health, COVID-19, and the syndemic: internal medicine facing the challenge

Internists are experts in complexity, and the COVID-19 pandemic is disclosing complex and unexpected interactions between communicable and non-communicable diseases, environmental factors, and socio-economic disparities. The medicine of complexity cannot be limited to facing comorbidities and to the clinical management of multifaceted diseases. Evidence indicates how climate change, pollution, demographic unbalance, and inequalities can affect the spreading and outcomes of COVID-19 in vulnerable communities. These elements cannot be neglected, and a wide view of public health aspects by a "one-health" approach is strongly and urgently recommended. According to World Health Organization, 35% of infectious diseases involving the lower respiratory tract depend on environmental factors, and infections from SARS-Cov-2 is not an exception. Furthermore, environmental pollution generates a large burden of non-communicable diseases and disabilities, increasing the individual vulnerability to COVID-19 and the chance for the resilience of large communities worldwide. In this field, the awareness of internists must increase, as privileged healthcare providers. They need to gain a comprehensive knowledge of elements characterizing COVID-19 as part of a syndemic. This is the case when pandemic events hit vulnerable populations suffering from the increasing burden of chronic diseases, disabilities, and social and economic inequalities. Mastering the interplay of such events requires a change in overall strategy, to adequately manage not only the SARS-CoV-2 infection but also the growing burden of non-communicable diseases by a "one health" approach. In this context, experts in internal medicine have the knowledge and skills to drive this change.

Cognitive dysfunction associated with COVID-19: Prognostic role of circulating biomarkers and microRNAs

COVID-19 is renowned as a multi-organ disease having subacute and long-term effects with a broad spectrum of clinical manifestations. The evolving scientific and clinical evidence demonstrates that the frequency of cognitive impairment after COVID-19 is high and it is crucial to explore more clinical research and implement proper diagnostic and treatment strategies. Several central nervous system complications have been reported as comorbidities of COVID-19. The changes in cognitive function associated with neurodegenerative diseases develop slowly over time and are only diagnosed at an already advanced stage of molecular pathology. Hence, understanding the common links between COVID-19 and neurodegenerative diseases will broaden our knowledge and help in strategizing prognostic and therapeutic approaches. The present review focuses on the diverse neurodegenerative changes associated with COVID-19 and will highlight the importance of major circulating biomarkers and microRNAs (miRNAs) associated with the disease progression and severity. The literature analysis showed that major proteins associated with central nervous system function, such as Glial fibrillary acidic protein, neurofilament light chain, p-tau 181, Ubiquitin C-terminal hydrolase L1, S100 calcium-binding protein B, Neuron-specific enolase and various inflammatory cytokines, were significantly altered in COVID-19 patients. Furthermore, among various miRNAs that are having pivotal roles in various neurodegenerative diseases, miR-146a, miR-155, Let-7b, miR-31, miR-16 and miR-21 have shown significant dysregulation in COVID-19 patients. Thus the review consolidates the important findings from the numerous studies to unravel the underlying mechanism of neurological sequelae in COVID-19 and the possible association of circulatory biomarkers, which may serve as prognostic predictors and therapeutic targets in future research.

Sequelae of COVID-19 among previously hospitalized patients up to 1 year after discharge: a systematic review and meta-analysis

OBJECTIVE

Although complications and clinical symptoms of COVID-19 have been elucidated, the prevalence of long-term sequelae of COVID-19 is less clear in previously hospitalized COVID-19 patients. This review and meta-analysis present the occurrence of different symptoms up to 1 year of follow-up for previously hospitalized patients.

METHODS

We performed a systematic review from PubMed and Web of Science using keywords such as "COVID-19", "SARS-CoV-2", "sequelae", "long-term effect" and included studies with at least 3-month of follow-up. Meta-analyses using random-effects models were performed to estimate the pooled prevalence for different sequelae. Subgroup analyses were conducted by different follow-up time, regions, age and ICU admission.

RESULTS

72 articles were included in the meta-analyses after screening 11,620 articles, identifying a total of 167 sequelae related to COVID-19 from 88,769 patients. Commonly reported sequelae included fatigue (27.5%, 95% CI 22.4-33.3%, range 1.5-84.9%), somnipathy (20.1%, 95% CI 14.7-26.9%, range 1.2-64.8%), anxiety (18.0%, 95% CI 13.8-23.1%, range 0.6-47.8%), dyspnea (15.5%, 95% CI 11.3-20.9%, range 0.8-58.4%), PTSD (14.6%, 95% CI 11.3-18.7%, range 1.2-32.0%), hypomnesia (13.4%, 95% CI 8.4-20.7%, range 0.6-53.8%), arthralgia (12.9%, 95% CI 8.4-19.2%, range 0.0-47.8%), depression (12.7%, 95% CI 9.3-17.2%, range 0.6-37.5%), alopecia (11.2%, 95% CI 6.9-17.6%, range 0.0-47.0%) over 3-13.2 months of follow-up. The prevalence of most symptoms reduced after > 9 months of follow-up, but fatigue and somnipathy persisted in 26.2% and 15.1%, respectively, of the patients over a year. COVID-19 patients from Asia reported a lower prevalence than those from other regions.

CONCLUSIONS

This review identified a wide spectrum of COVID-19 sequelae in previously hospitalized COVID-19 patients, with some symptoms persisting up to 1 year. Management and rehabilitation strategies targeting these symptoms may improve quality of life of recovered patients.

Drug genetic associations with COVID-19 manifestations: a data mining and network biology approach

Available drugs have been used as an urgent attempt through clinical trials to minimize severe cases of hospitalizations with Coronavirus disease (COVID-19), however, there are limited data on common pharmacogenomics affecting concomitant medications response in patients with comorbidities. To identify the genomic determinants that influence COVID-19 susceptibility, we use a computational, statistical, and network biology approach to analyze relationships of ineffective concomitant medication with an adverse effect on patients. We statistically construct a pharmacogenetic/biomarker network with significant drug-gene interactions originating from gene-disease associations. Investigation of the predicted pharmacogenes encompassing the gene-disease-gene pharmacogenomics (PGx) network suggests that these genes could play a significant role in COVID-19 clinical manifestation due to their association with autoimmune, metabolic, neurological, cardiovascular, and degenerative disorders, some of which have been reported to be crucial comorbidities in a COVID-19 patient.