We aimed to develop objective criteria for cognitive dysfunction associated with the post-COVID syndrome.Four hundred and four patients with post-COVID syndrome from two centers were evaluated with comprehensive neuropsychological batteries. The International Classification for Cognitive Disorders in Epilepsy (IC-CoDE) framework was adapted and implemented. A healthy control group of 145 participants and a complementary data-driven approach based on unsupervised machine-learning clustering algorithms were also used to evaluate the optimal classification and cutoff points.According to the developed criteria, 41.2% and 17.3% of the sample were classified as having at least one cognitive domain impaired using -1 and -1.5 standard deviations as cutoff points. Attention/processing speed was the most frequently impaired domain. There were no differences in base rates of cognitive impairment between the two centers. Clustering analysis revealed two clusters, although with an important overlap (silhouette index 0.18-0.19). Cognitive impairment was associated with younger age and lower education levels, but not hospitalization.We propose a harmonization of the criteria to define and classify cognitive impairment in the post-COVID syndrome. These criteria may be extrapolated to other neuropsychological batteries and settings, contributing to the diagnosis of cognitive deficits after COVID-19 and facilitating multicenter studies to guide biomarker investigation and therapies. 

Development of criteria for cognitive dysfunction in post-COVID syndrome: the IC-CoDi-COVID approach

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.

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

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.

/pdf/cognitive-impairment-after-post-acute-covid-19-infection-a-2vyqser9.pdf

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

https://doi.org/10.1016/j.exger.2022.111946

Evolution of physical function, cognition, depressive mood, and quality of life during the Covid-19 pandemic in prefrail elderly people: A longitudinal cohort study (Covid-Mefap)

Long-term neurological and mental complications of COVID-19, the so-called post-COVID syndrome or long COVID, affect the quality of life. The most persistent manifestations of long COVID include fatigue, anosmia/hyposmia, insomnia, depression/anxiety, and memory/attention deficits. The physiological basis of neurological and psychiatric disorders is still poorly understood. This review summarizes the current knowledge of neurological sequelae in post-COVID patients and discusses brain demyelination as a possible mechanism of these complications with a focus on neuroimaging findings. Numerous reviews, experimental and theoretical studies consider brain demyelination as one of the mechanisms of the central neural system impairment. Several factors might cause demyelination, such as inflammation, direct effect of the virus on oligodendrocytes, and cerebrovascular disorders, inducing myelin damage. There is a contradiction between the solid fundamental basis underlying demyelination as the mechanism of the neurological injuries and relatively little published clinical evidence related to demyelination in COVID-19 patients. The reason for this probably lies in the fact that most clinical studies used conventional MRI techniques, which can detect only large, clearly visible demyelinating lesions. A very limited number of studies use specific methods for myelin quantification detected changes in the white matter tracts 3 and 10 months after the acute phase of COVID-19. Future research applying quantitative MRI assessment of myelin in combination with neurological and psychological studies will help in understanding the mechanisms of post-COVID complications associated with demyelination.

/pdf/role-of-demyelination-in-the-persistence-of-neurological-and-118fjr50.pdf

Role of Demyelination in the Persistence of Neurological and Mental Impairments after COVID-19

https://doi.org/10.1016/j.cortex.2022.04.006

COVID-19 associated cognitive impairment: A systematic review

Introduction Few studies have objectively evaluated cognitive deficits after the acute phase of COVID-19 disease. Moreover, the role of apolipoprotein E (APOE) genotypes in cognitive decline in patients with COVID-19 has not been evaluated yet. Methods This cross-sectional study was conducted in confirmed cases of COVID-19 patients with neurological symptoms that persisted for more than 3 months from the onset. We determined APOE genotypes. Results The final sample consisted of 141 patients. The most frequent APOE genotype was E3/E3 (N = 95; 67.3%). In total, 93 patients (65.9%) had memory impairment symptoms as the main complaint, objectively confirmed through screening tests in 25 patients (17.7%). Patients with cognitive impairment had a lower frequency of anosmia than the normal and subjective cognitive decline (SCD) groups (p = 0.005). In addition, depression was recurrent in the cognitive impairment group and the SCD group (p = 0.046). Cognitive impairment was significantly more frequent in hospitalized patients and those with a lower education level. Cognitive status was not associated with APOE genotypes. Discussion Hospitalized patients had more severe infection with a greater possibility of systemic complications, greater inflammatory response, and prolonged hospitalization, which could impact cognitive performance. Cognitive impairment in patients with COVID-19 does not necessarily involve specific APOE polymorphisms. However, psychiatric disorders may also be responsible for cognitive complaints. Cognitive complaints are frequent in patients with COVID-19, even after the acute phase of the disease and in mild cases. Hospitalized participants and depressed patients may have a higher risk of cognitive impairment. APOE genotypes or haplotypes may not significantly play a role in COVID-19 cognitive impairment.

/pdf/long-covid-cognitive-impairment-cognitive-assessment-and-1ifl8vsw.pdf

Long-covid cognitive impairment: Cognitive assessment and apolipoprotein E (APOE) genotyping correlation in a Brazilian cohort

Abstract 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. 

/pdf/central-hypersomnia-and-chronic-insomnia-expanding-the-3vtfm5yn.pdf

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

Central Sleep Hypersomnia after Covid-19 Infection: Serial Case Reports

COVID‐19 neurological manifestations were demonstrated during the pandemic, including cognitive impairment. Objectives: To determine the prevalence of cognitive and behavioral complaints (such as dementia, MCI or SCD) in a outpatient sample with recent SARS‐COV2 infection. Specific: Evaluate the association of cognitive impairment with the presence of the polymorphism found in the APOE gene and with respiratory disease

https://onlinelibrary.wiley.com/doi/pdfdirect/10.1002/alz.059664

D. N. Oliveira

Papers

COVID-19 associated cognitive impairment: A systematic review

Long-covid cognitive impairment: Cognitive assessment and apolipoprotein E (APOE) genotyping correlation in a Brazilian cohort

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

Central Sleep Hypersomnia after Covid-19 Infection: Serial Case Reports

Neurological and cognitive impairment in COVID‐19: clinical characterization andepidemiological