Comprehensive Clinical Characterisation of Brain Fog in Adults Reporting Long COVID Symptoms

Persistent cognitive symptoms in mild COVID-19 infection: a retrospective cohort study

BACKGROUND

The COVID-19 pandemic represented a healthcare challenge of unparalleled magnitude worldwide. As patients recovered from the acute infection, a new challenge emerged, i.e., the development of post-acute symptoms. The main goal of this study was to evaluate the trajectory of cognitive symptoms since the acute phase of COVID-19 among patients followed through a telehealth program in Brazil.

METHODS

A retrospective cohort study was conducted with confirmed COVID-19 patients followed by a Brazilian telehealth program who presented cognitive symptoms in the acute phase of infection. The objective of the current analysis was to assess the persistence or remission of cognitive symptoms at 24 weeks after the onset of acute COVID-19 symptoms, as well as the factors associated with such manifestations. The study used chi-square tests and multivariate logistic regression models to assess the association between patients' parameters and the presence of cognitive symptoms. A backward stepwise method was applied to define significant characteristics, which were then evaluated using odds ratios and 95% confidence intervals.

RESULTS

Among 319 patients who had cognitive symptoms during acute COVID-19, 89 (27.9%) reported persistence of cognitive symptoms for more than 24 weeks from the acute onset of the infection. Female sex (OR 2.33 [95% CI 1.23-4.43]) and having been infected during the second wave of COVID-19 (OR 2.30 [95% CI 1.34-3.96]) were associated with the persistence of symptoms beyond 24 weeks.

CONCLUSIONS

Approximately one-third of patients with COVID-19, mainly women and people infected during the second wave of infection, experienced persistent cognitive symptoms.

Brain fog

'Brain fog' is a term that patients use increasingly frequently in the neurology clinic. We may think that we know what patients are talking about but at least some of the time we are likely to be getting it wrong. Patients use the term 'brain fog' to describe a wide range of subjective phenomena and symptoms. This paper suggests useful lines of questioning, and discusses the clinical correlates of a range of common 'brain fog' experiences.

Brain Fog and Cognitive Dysfunction in Posttraumatic Stress Disorder: An Evidence-Based Review

The term "brain fog" has long been used both colloquially and in research literature in reference to various neurocognitive phenomenon that detract from cognitive efficiency. We define "brain fog" as the subjective experience of cognitive difficulties, in keeping with the most common colloquial and research use of the term. While a recent increase in use of this term has largely been in the context of the post-coronavirus-19 condition known as long COVID, "brain fog" has also been discussed in relation to several other conditions including mental health conditions such as post-traumatic stress disorder (PTSD). PTSD is associated with both subjective cognitive complaints and relative deficits on cognitive testing, but the phenomenology and mechanisms contributing to "brain fog" in this population are poorly understood. PTSD psychopathology across cognitive, affective and physiological symptom domains have been tied to "brain fog". Furthermore, dissociative symptoms common in PTSD also contribute to the experience of "brain fog". Comorbid physical and mental health conditions may also increase the risk of experiencing "brain fog" among individuals with PTSD. Considerations for the assessment of "brain fog" in PTSD as part of psychodiagnostic assessment are discussed. While standard psychological intervention for PTSD is associated with a reduction in subjective cognitive deficits, other cognitive interventions may be valuable when "brain fog" persists following PTSD remission or when "brain fog" interferes with treatment. Limitations of current research on "brain fog" in PTSD include a lack of consistent definition and operationalization of "brain fog" in the literature, as well as limited tools for measurement. Future research should address these limitations, as well as further evaluate the use of cognitive remediation as an intervention for "brain fog".

Neuropsychiatric Manifestations of Long COVID-19: A Narrative Review of Clinical Aspects and Therapeutic Approaches

The COVID-19 (C-19) pandemic has highlighted the significance of understanding the long-term effects of this disease on the quality of life of those infected. Long COVID-19 (L-C19) presents as persistent symptoms that continue beyond the main illness period, usually lasting weeks to years. One of the lesser-known but significant aspects of L-C19 is its impact on neuropsychiatric manifestations, which can have a profound effect on an individual's quality of life. Research shows that L-C19 creates neuropsychiatric issues such as mental fog, emotional problems, and brain disease symptoms, along with sleep changes, extreme fatigue, severe head pain, tremors with seizures, and pain in nerves. People with cognitive problems plus fatigue and mood disorders experience great difficulty handling everyday activities, personal hygiene, and social interactions. Neuropsychiatric symptoms make people withdraw from social activity and hurt relationships, thus causing feelings of loneliness. The unpredictable state of L-C19 generates heavy psychological pressure through emotional suffering, including depression and anxiety. Neuropsychiatric changes such as cognitive impairment, fatigue, and mood swings make it hard for people to work or study effectively, which decreases their output at school or work and lowers their job contentment. The purpose of this narrative review is to summarize the clinical data present in the literature regarding the neuropsychiatric manifestations of L-C19, to identify current methods of diagnosis and treatment that lead to correct management of the condition, and to highlight the impact of these manifestations on patients' quality of life.

Defining brain fog across medical conditions

'Brain fog' is commonly reported in more than a dozen chronic diseases, but what is it? We review research across conditions which has characterised brain fog and evaluate its definitions and objective correlates. Brain fog has been used to refer to a variable set of overlapping symptoms implicating cognition, fatigue, and affect. It has been defined as a distinct symptom, a syndrome, or a nonspecific term. We consider the evidence that brain fog is a transdiagnostic entity with a common phenomenology and profile of objective cognitive deficits. We discuss where these commonalities arise and argue that linguistic ambiguity, shared cognitive impairments, and noncognitive factors are more likely than shared neurobiology. We suggest how future research might apply existing tools to disambiguate the phenomena that brain fog conflates.

How Are Brain Fog Symptoms Related to Diet, Sleep, Mood and Gastrointestinal Health? A Cross-Sectional Study

Background and Objectives: Brain fog, characterized by cognitive difficulties such as memory impairment, lack of focus, and mental fatigue, is a common symptom reported during recovery from COVID-19, particularly in long COVID cases. This study explores potential triggers such as sleep quality, mood, and gastrointestinal health and examines the link between adherence to the MIND diet and brain fog severity. Materials and Methods: A cross-sectional study was conducted between 1 July and 15 December 2022. The questionnaire assessed brain fog symptoms, dietary habits, sleep quality, mood, and gastrointestinal symptoms. Linear regression analysis examined the relationships between brain fog symptoms, demographic factors, sleep quality, MIND diet adherence, and gastrointestinal symptoms. Results: Brain Fog Scale (BFS) scores were significantly higher in individuals who had COVID-19 (p < 0.05) and even higher in those with reinfection. Women had higher BFS and Brain Fog Severity Score (BFSS), MIND Diet, The Gastrointestinal Symptom Rating Scale (GSRS), Brief Mood Introspection Scale (BMIS) Pleasant-Unpleasant scores (p < 0.05). BFS and BFSS were positively correlated with GSRS (p < 0.05), while no correlation was found with MIND diet adherence. A negative correlation was observed between BFS and Sleep Quality Scale (SQS) (p < 0.05), but this was not significant in regression (p = 0.367). GSRS, Pleasant-Unpleasant Dimension, and Arousal-Calm Dimension were significant predictors of BFS (R = 0.599, R2 = 0.358, p < 0.01). Conclusions: This study identifies being female as a risk factor for brain fog symptoms, with women reporting higher BFS and BFSS scores. While sleep quality showed a negative correlation with brain fog symptoms, this relationship was not significant in the regression model, suggesting that other factors, such as mood and gastrointestinal symptoms, may play a more dominant role. However, adherence to the MIND diet showed no significant relationship with brain fog symptoms. These findings suggest that addressing mood and gastrointestinal health may be key to managing brain fog in long COVID.

A Systems Neuroscience Approach to Diagnosis and Rehabilitation of Post COVID Neurological Syndrome Based on the Systems Neuroscience Test Battery (SNTB) Study Protocol

The proposed study reports the design and development of a rapid screening tool, the Systems Neuroscience Test Battery (SNTB), for diagnosing and evaluating the neurological manifestations of Post-COVID-19 Neurological Syndrome (PCNS) within the broader context of Post-Acute Sequelae to COVID-19 (PASC). The SNTB is designed to incorporate a behaviorally relevant Telehealth component that enhances consumer confidence in symptom discrimination, management of PCNS, and guides rehabilitation programs while allowing for continuous evaluation of intervention effectiveness.The study employs a longitudinal design, with telehealth and routine blood assessments conducted at three-month intervals, including at least two follow-ups post-recruitment. These assessments will involve Consumer-Reported Symptoms, Clinical History, Neuropsychological Data, and Timed Psychophysics, aimed at rapid screening of PCNS-related symptoms including 'brain fog" and its affect on visually driven attention, cognition and visually driven motor behaviors. These assessments are intended to validate the characteristics of 'brain fog' and identify predictive behavioral biomarkers for the development of PCNS.The target population includes adults aged 18-65 who have experienced persistent neurological symptoms for at least three months following a confirmed COVID-19 infection. Exclusion criteria include individuals unable to undergo radiological examinations, such as pregnant women or those with contraindications to MRI, ensuring the robustness of the sample and reducing potential selection bias.The SNTB tool will facilitate the online identification of predictive biomarkers for PCNS and aid in the discovery of effective molecular biomarker combinations for medical intervention and rehabilitation. Complementary to the Telehealth Assessment, hospital facilities will be utilized for radiological and blood-based molecular assessments, ensuring concurrent profiling of structural and functional changes during 'brain fog' and recovery from PCNS symptoms.

Cognitive domains affected post-COVID-19; a systematic review and meta-analysis

BACKGROUND AND PURPOSE

This review aims to characterize the pattern of post-COVID-19 cognitive impairment, allowing better prediction of impact on daily function to inform clinical management and rehabilitation.

METHODS

A systematic review and meta-analysis of neurocognitive sequelae following COVID-19 was conducted, following PRISMA-S guidelines. Studies were included if they reported domain-specific cognitive assessment in patients with COVID-19 at >4 weeks post-infection. Studies were deemed high-quality if they had >40 participants, utilized healthy controls, had low attrition rates and mitigated for confounders.

RESULTS

Five of the seven primary Diagnostic and Statistical Manual of Mental Disorders (DSM-5) cognitive domains were assessed by enough high-quality studies to facilitate meta-analysis. Medium effect sizes indicating impairment in patients post-COVID-19 versus controls were seen across executive function (standardised mean difference (SMD) -0.45), learning and memory (SMD -0.55), complex attention (SMD -0.54) and language (SMD -0.54), with perceptual motor function appearing to be impacted to a greater degree (SMD -0.70). A narrative synthesis of the 56 low-quality studies also suggested no obvious pattern of impairment.

CONCLUSIONS

This review found moderate impairments across multiple domains of cognition in patients post-COVID-19, with no specific pattern. The reported literature was significantly heterogeneous, with a wide variety of cognitive tasks, small sample sizes and disparate initial disease severities limiting interpretability. The finding of consistent impairment across a range of cognitive tasks suggests broad, as opposed to domain-specific, brain dysfunction. Future studies should utilize a harmonized test battery to facilitate inter-study comparisons, whilst also accounting for the interactions between COVID-19, neurological sequelae and mental health, the interplay between which might explain cognitive impairment.

Acute and long-term effects of COVID-19 on brain and mental health: A narrative review

BACKGROUND

COVID infection has been associated with long term sequalae (Long COVID) which include neurological and behavioral effects in thousands of patients, but the etiology and scope of symptoms is not well understood. This paper reviews long term sequelae of COVID on brain and mental health in patients with the Long COVID syndrome.

METHODS

This was a literature review which queried databases for Pubmed, Psychinfo, and Medline for the following topics for January 1, 2020-July 15, 2023: Long COVID, PASC, brain, brain imaging, neurological, neurobiology, mental health, anxiety, depression.

RESULTS

Tens of thousands of patients have developed Long COVID, with the most common neurobehavioral symptoms anosmia (loss of smell) and fatigue. Anxiety and mood disorders are elevated and seen in about 25% of Long COVID patients. Neuropsychological testing studies show a correlation between symptom severity and cognitive dysfunction, while brain imaging studies show global decreases in gray matter and alterations in olfactory and other brain areas.

CONCLUSIONS

Studies to date show an increase in neurobehavioral disturbances in patients with Long COVID. Future research is needed to determine mechanisms.

Neurological, psychological, psychosocial complications of long-COVID and their management

Since it first appeared, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has had a significant and lasting negative impact on the health and economies of millions of individuals all over the globe. At the level of individual health too, many patients are not recovering fully and experiencing a long-term condition now commonly termed 'long-COVID'. Long-COVID is a collection of symptoms which must last more than 12 weeks following initial COVID infection, and which cannot be adequately explained by alternate diagnoses. The neurological and psychosocial impact of long-COVID is itself now a global health crisis and therefore preventing, diagnosing, and managing these patients is of paramount importance. This review focuses primarily on: neurological functioning deficits; mental health impacts; long-term mood problems; and associated psychosocial issues, among patients suffering from long-COVID with an eye towards the neurological basis of these symptoms. A concise account of the clinical relevance of the neurological and psychosocial impacts of long-COVID, the effects on long-term morbidity, and varied approaches in managing patients with significant chronic neurological symptoms and conditions was extracted from the literature, analysed and reported. A comprehensive account of plausible pathophysiological mechanisms involved in the development of long-COVID, its management, and future research needs have been discussed.

Pathophysiological, Neuropsychological, and Psychosocial Influences on Neurological and Neuropsychiatric Symptoms of Post-Acute COVID-19 Syndrome: Impacts on Recovery and Symptom Persistence

Although the impact of post-acute COVID-19 syndrome (PACS) on patients and public health is undeniably significant, its etiology remains largely unclear. Much research has been conducted on the pathophysiology, shedding light on various aspects; however, due to the multitude of symptoms and clinical conditions that directly or indirectly define PACS, it is challenging to establish definitive causations. In this exploration, through systematically reviewing the latest pathophysiological findings related to the neurological symptoms of the syndrome, we aim to examine how psychosocial and neuropsychological symptoms may overlap with neurological ones, and how they may not only serve as risk factors but also contribute to the persistence of some primary symptoms of the disorder. Findings from our synthesis suggest that psychological and psychosocial factors, such as anxiety, depression, and loneliness, may interact with neurological symptoms in a self-reinforcing feedback loop. This cycle seems to be affecting both physical and psychological distress, potentially increasing the persistence and severity of PACS symptoms. By pointing out this interaction, in this review study, we attempt to offer a new perspective on the interconnected nature of psychological, psychosocial, and neurological factors, emphasizing the importance of integrated treatment approaches to disrupt this cycle and improve outcomes when possible.

Defining and measuring long COVID fatigue: a scoping review

OBJECTIVE

Long COVID encompasses a range of symptoms in which fatigue is one of the most prevalents. It is clear from other conditions that the definition and measurement of fatigue can be complex, but it is not clear how fatigue is defined and measured in long COVID. To advance our understanding, this review summarises the definitions and measures of long COVID fatigue being used by researchers.

DESIGN

Scoping review following JBI methodology and reports using the Preferred Reporting Items for Systematic Reviews and Meta-analyses extension for scoping reviews.

DATA SOURCES

Medline, Scopus, CINAHL, PsycINFO, EMCARE, Web of Science, Epistemonikos, Cochrane Central Register of Controlled Trials, Dimensions, Overton and ProQuest Dissertation & Theses Database were searched from January 2020 to May 2023.

ELIGIBILITY CRITERIA

This review included quantitative and qualitative studies that included any definition of long COVID and/or measurement tool that purported to quantify either the impact, severity or symptoms of long COVID fatigue.

DATA EXTRACTION AND SYNTHESIS

Two independent reviewers screened the title, abstracts and full texts of the selected studies based on the inclusion criteria. Data extraction was performed by two independent reviewers. The data were summarised in tabular format and a narrative summary.

RESULTS

The search retrieved 9839 studies, of which 57 met the inclusion criteria. Only 21 (37%) provided a definition of fatigue. Definitions ranged across physical, mental, cognitive, emotional, psychosocial, central, peripheral, postexertional symptom exacerbation and general dimensions of fatigue. Fifty-five (96%) used a measurement or assessment of fatigue. Twenty-six measures of fatigue were identified: 21 self-report measures (eg, Fatigue Assessment Scale) and five fatigability measures that purport to reflect changes in physiological processes that contribute to or reflect fatigue (eg, change in force generating capacity of a muscle).

CONCLUSIONS

The definitions identified demonstrate considerable diversity, each highlighting different dimensions of long COVID fatigue. Long COVID fatigue was predominantly measured through self-report methods, which were problematic. There is an urgent need to better understand long COVID fatigue and to identify the different mechanisms involved. In order to do this, we need consistency with the language around fatigue and its measurement within research and across disciplines.

REVIEW REGISTRATION

The protocol has been registered on open science framework (https://doi.org/10.17605/OSF.IO/HNF8Z).

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

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

Acceptability and Feasibility of the English Version of Elevida, a Self-Guided Online Fatigue Intervention for People With Multiple Sclerosis

BACKGROUND

Fatigue is common in multiple sclerosis (MS); it significantly impairs quality of life, and treatment options are limited. A randomized controlled trial of Elevida, a self-guided, online German fatigue intervention, showed significant benefit. We tested an English version of Elevida with people with MS in Australia.

METHODS

Participants were volunteers with MS who self-reported at least mild fatigue (≥ 43 on the Fatigue Scale for Motor and Cognitive Functions scale), some mobility (Expanded Disability Status Scale < 8), and no or mild cognitive difficulties (≤ 32 on the Multiple Sclerosis Neuropsychological Questionnaire). Participants completed the 9-week English Elevida program, commenting on and rating its acceptability. The Chalder Fatigue Scale was completed at baseline, end-of-program, and 2 months later. We undertook qualitative (thematic analysis) and quantitative (before/after differences, tested using paired t test) analyses.

RESULTS

Thirty-eight people with MS expressed an interest in the study; 26 were eligible; 20 began the study. Fifteen participants (75%) completed the program (mean [SD]: 58.9 [10.5] years of age, 67% women, 9 with relapsing MS, 6 with progressive MS). Over 90% of completing participants rated acceptability as good or very good, and approximately 70% found the program helpful. Three themes were identified: Positive or negative comments on program features, incorrect assumptions in program content, and personal experiences and reflections. Significant improvement (P < .01) in fatigue scores from baseline to program completion was maintained 2 months after program completion.

CONCLUSIONS

Elevida was acceptable and effective for MS-related fatigue. Identified themes will guide further development of the program to satisfy users' sense of autonomy, competence, and relatedness.

Methylphenidate for the Treatment of Post-COVID Cognitive Dysfunction (Brain Fog)

A substantial number of patients develop cognitive dysfunction after contracting severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), significantly contributing to long-coronavirus disease (COVID) morbidity. Despite the urgent and overwhelming clinical need, there are currently no proven interventions to treat post-COVID cognitive dysfunction (PCCD). Psychostimulants like methylphenidate may enhance both noradrenergic and dopaminergic pathways in mesolimbic and pre-frontal areas, thus improving memory and cognition. We present a case series of six patients who were treated at the Johns Hopkins Post-Acute COVID-19 Team (PACT) clinic for PCCD with methylphenidate 5 - 20 mg in the context of routine clinical care and followed for 4 to 8 weeks. Baseline and post-treatment outcomes included subjective cognitive dysfunction and objective performance on a battery devised to measure cognitive dysfunction in long-COVID patients. Three out of the six patients reported subjective improvement with methylphenidate, one patient described it as "notable" and another as "marked" improvement in memory and concentration. We also found significant pre-treatment subjective complaints of cognitive dysfunction; however, formal cognitive assessment scores were not severely impaired. A statistically significant difference in pre and post scores, favoring intervention, was found for the following cognitive assessments: Hopkins verbal learning test (HVLT) immediate recall, HVLT delayed recall and category-cued verbal fluency. The current series demonstrates promising neurocognitive effects of methylphenidate for long-COVID cognitive impairment, particularly in recall and verbal fluency domains.

Prevalence and co-occurrence of cognitive impairment in children and young people up to 12-months post infection with SARS-CoV-2 (Omicron variant)

BACKGROUND

Cognitive impairment is often reported after SARS-CoV-2 infection, yet evidence gaps remain. We aimed to (i) report the prevalence and characteristics of children and young people (CYP) reporting "brain fog" (i.e., cognitive impairment) 12-months post PCR-proven SARS-CoV-2 infection and determine whether differences by infection status exist and (ii) explore the prevalence of CYP experiencing cognitive impairment over a 12-month period post-infection and investigate the relationship between cognitive impairment and poor mental health and well-being, mental fatigue and sleep problems.

METHODS

The Omicron CLoCk sub-study, set up in January 2022, collected data on first-time PCR-test-positive and PCR-proven reinfected CYP at time of testing and at 3-, 6- and 12-months post-testing. We describe the prevalence of cognitive impairment at 12-months, indicating when it was first reported. We characterise CYP experiencing cognitive impairment and use chi-squared tests to determine whether cognitive impairment prevalence varied by infection status. We explore the relationship between cognitive impairment and poor mental health and well-being, mental fatigue and trouble sleeping using validated scales. We examine associations at 3-, 6- and 12-months post-testing by infection status using Mann-Whitney U and chi-square tests.

RESULTS

At 12-months post-testing, 7.0 % (24/345) of first-positives and 7.5 % (27/360) of reinfected CYP experienced cognitive impairment with no difference between infection-status groups (p = 0.78). The majority of these CYP experienced cognitive impairment for the first time at either time of testing or 3-months post-test (no difference between the infection-status groups; p = 0.60). 70.8 % of first-positives experiencing cognitive impairment at 12-months, were 15-to-17-years-old as were 33.3 % of reinfected CYP experiencing cognitive impairment (p < 0.01). Consistently at all time points post-testing, CYP experiencing cognitive impairment were more likely to score higher on all Strengths and Difficulties Questionnaire subscales, higher on the Chalder Fatigue sub-scale for mental fatigue, lower on the Short Warwick-Edinburgh Mental Wellbeing Scale and report more trouble sleeping.

CONCLUSIONS

CYP have a fluctuating experience of cognitive impairment by 12-months post SARS-CoV-2-infection. Cognitive impairment is consistently correlated with poorer sleep, behavioural and emotional functioning over a 12-month period. Clinicians should be aware of cognitive impairment post-infection and its co-occurring nature with poorer sleep, behavioural and mental health symptoms.

Subjective brain fog: a four-dimensional characterization in 25,796 participants

Importance

Brain fog is associated with significant morbidity and reduced productivity and gained increasing attention after COVID-19. However, this subjective state has not been systematically characterised.

Objective

To characterise self-reported brain fog.

Design

We systematically studied the cross-sectional associations between 29 a priori variables with the presence of "brain fog." The variables were grouped into four categories: demographics, symptoms and functional impairments, comorbidities and potential risk factors (including lifestyle factors), and cognitive score. Univariate methods determined the correlates of brain fog, with long-COVID and non-long-COVID subgroups. XGBoost machine learning model retrospectively characterised subjective brain fog. Bonferroni-corrected statistical significance was set at 5%.

Setting

Digital application for remote data collection.

Participants

25,796 individuals over the age of 18 who downloaded and completed the application.

Results

7,280 of 25,796 individuals (28.2%) reported experiencing brain fog, who were generally older (mean brain fog 35.7 ± 11.9 years vs. 32.8 ± 11.6 years, p < 0.0001) and more likely to be female (OR = 1.2, p < 0.001). Associated symptoms and functional impairments included difficulty focusing or concentrating (OR = 3.3), feeling irritable (OR = 1.6), difficulty relaxing (OR = 1.2, all p < 0.0001), difficulty following conversations (OR = 2.2), remembering appointments (OR = 1.9), completing paperwork and performing mental arithmetic (ORs = 1.8, all p < 0.0001). Comorbidities included long-COVID-19 (OR = 3.8, p < 0.0001), concussions (OR = 2.4, p < 0.0001), and higher migraine disability assessment scores (MIDAS) (+34.1%, all p < 0.0001). Cognitive scores were marginally lower with brain fog (-0.1 std., p < 0.001). XGBoost achieved a training accuracy of 85% with cross-validated accuracy of 74%, and the features most predictive of brain fog in the model were difficulty focusing and following conversations, long-COVID, and severity of migraines.

Conclusions and relevance

This is the largest study characterising subjective brain fog as an impairment of concentration associated with functional impairments in activities of daily living. Brain fog was particularly associated with a history of long-COVID-19, migraines, concussion, and with 0.1 standard deviations lower cognitive scores, especially on modified Stroop testing, suggesting impairments in the ability to inhibit cognitive interference. Further prospective studies in unselected brain fog sufferers should explore the full spectrum of brain fog symptoms to differentiate it from its associated conditions.

The association of multiple sclerosis, traumatic brain injury, and spinal cord injury to acute and long COVID-19 outcomes

BACKGROUND

Although persons with disabilities are a high-risk group, little is known about the association between specific disabling conditions and acute or long COVID outcomes.

OBJECTIVE

To examine the severity of acute SARS-CoV-2 infection and post-COVID outcomes among people with a preexisting diagnosis of multiple sclerosis (MS), spinal cord injury (SCI), or traumatic brain injury (TBI).

METHODS

This was a retrospective cohort study using the TrinetX Research Database, a large representative database of medical records. COVID-19-positive persons with MS, SCI, or TBI (cases) were matched 1:1 on age, gender, race, ethnicity, and comorbidities to COVID-19-positive persons without these diagnoses (controls). The main outcomes assessed were hospitalization for acute COVID-19, length of stay (LOS), the total number of hospitalizations, mortality, and incidence of six prevalent post-COVID sequelae within 6 months following a COVID-19 diagnosis.

RESULTS

There were 388,297 laboratory-confirmed COVID-19 cases identified. Of these cases, 2204 individuals had one of the following preexisting diagnoses: 51.3% TBI, 31.4% MS, and 17.3% SCI. People with TBI, MS, and SCI were significantly more likely to be hospitalized for COVID-19 (odds ratio [OR] = 1.22, 95% confidence interval [CI] = 1.03-1.46) than matched controls. There was no difference in LOS, total hospitalizations, or mortality during the 6 months following the initial COVID diagnosis. Multivariable analyses reveal that persons with TBI, MS, and SCI were more likely to experience new weakness (OR = 1.54, 95% CI = 1.19-2.00), mobility difficulties (OR = 1.66, 95% CI = 1.17-2.35), and cognitive dysfunction (OR = 1.79, 95% CI = 1.38-2.33) than controls, even after controlling for the presence of these symptoms prior to their COVID infection and other risk factors. There were no differences in fatigue, pain, or dyspnea.

CONCLUSIONS

Having a history of MS, SCI or TBI was not associated with higher mortality risk from COVID-19. However, associations between these diagnoses and postacute COVID-19 symptoms raise concern about widening health outcome disparities for individuals with such potentially disabling conditions following COVID-19 infection.

Post-COVID-19 cognitive symptoms in patients assisted by a teleassistance service: a retrospective cohort study

Introduction

Four years after the onset of the COVID-19 pandemic, the frequency of long-term post-COVID-19 cognitive symptoms is a matter of concern given the impact it may have on the work and quality of life of affected people.

Objective

To evaluate the incidence of post-acute COVID-19 cognitive symptoms, as well as the associated risk factors.

Methods

Retrospective cohort, including outpatients with laboratory-confirmed COVID-19 and who were assisted by a public telehealth service provided by the Telehealth Network of Minas Gerais (TNMG), during the acute phase of the disease, between December/2020 and March/2022. Data were collected through a structured questionnaire, applied via phone calls, regarding the persistence of COVID-19 symptoms after 12 weeks of the disease. Cognitive symptoms were defined as any of the following: memory loss, problems concentrating, word finding difficulties, and difficulty thinking clearly.

Results

From 630 patients who responded to the questionnaire, 23.7% presented cognitive symptoms at 12 weeks after infection. These patients had a higher median age (33 [IQR 25-46] vs. 30 [IQR 24-42] years-old, p = 0.042) with a higher prevalence in the female sex (80.5% vs. 62.2%, p < 0.001) when compared to those who did not present cognitive symptoms, as well as a lower prevalence of smoking (8.7% vs. 16.2%, p = 0.024). Furthermore, patients with persistent cognitive symptoms were more likely to have been infected during the second wave of COVID-19 rather than the third (31.0% vs. 21.3%, p = 0.014). Patients who needed to seek in-person care during the acute phase of the disease were more likely to report post-acute cognitive symptoms (21.5% vs. 9.3%, p < 0,001). In multivariate logistic regression analysis, cognitive symptoms were associated with female sex (OR 2.24, CI 95% 1.41-3.57), fatigue (OR 2.33, CI 95% 1.19-4.56), depression (OR 5.37, CI 95% 2.19-13.15) and the need for seek in-person care during acute COVID-19 (OR 2.23, CI 95% 1.30-3.81).

Conclusion

In this retrospective cohort of patients with mostly mild COVID-19, cognitive symptoms were present in 23.7% of patients with COVID-19 at 12 weeks after infection. Female sex, fatigue, depression and the need to seek in-person care during acute COVID-19 were the risk factors independently associated with this condition.

Brain fog in central disorders of hypersomnolence: a review

Brain fog is an undefined term describing a cluster of symptoms related to fatigue and impaired memory, attention, and concentration. Brain fog or brain fog-like symptoms have been reported in central disorders of hypersomnolence and in a range of seemingly unrelated disorders, including coronavirus disease 2019, major depressive disorder, multiple sclerosis, lupus, and celiac disease. This narrative review summarizes current evidence and proposes a consensus definition for brain fog. Brain fog is prevalent in narcolepsy and idiopathic hypersomnia, with more than three-quarters of patients with either disorder reporting this symptom in a registry study; it has also been reported as particularly difficult to treat in idiopathic hypersomnia. Studies directly evaluating brain fog are rare; tools for evaluating this symptom cluster typically are patient reports, with few objective measures validated in any disorder. Evaluating brain fog is further complicated by confounding symptoms, such as excessive daytime sleepiness, which is a hallmark of hypersomnolence disorders. No treatments specifically address brain fog. The paucity of literature, assessment tools, and medications for brain fog highlights the need for research leading to better disambiguation and treatment. Until a clear consensus definition is established, we propose brain fog in hypersomnia disorders be defined as a cognitive dysfunction that may or may not be linked with excessive sleepiness, related to an underlying neuronal dysfunction, which reduces concentration and impairs information processing, leading to a complaint of lack of clarity of mental thinking and awareness.

CITATION

Rosenberg R, Thorpy MJ, Doghramji K, Morse AM. Brain fog in central disorders of hypersomnolence: a review. J Clin Sleep Med. 2024;20(4):643-651.

Efficacy of dual-task augmented reality rehabilitation in non-hospitalized adults with self-reported long COVID fatigue and cognitive impairment: a pilot study

BACKGROUND

Cognitive impairment and chronic fatigue represent common characteristics of the long COVID syndrome. Different non-pharmacological treatments have been proposed, and physiotherapy has been proposed to improve the symptoms. This study aimed to evaluate the effects of a dual-task augmented reality rehabilitation protocol in people with long COVID fatigue and cognitive impairment.

METHODS AND MATERIALS

Ten non-hospitalized adults with reported fatigue and "brain fog" symptoms after COVID (7/10 females, 50 years, range 41-58) who participated in 20 sessions of a 1-h "dual-task" training, were compared to 10 long COVID individuals with similar demographics and symptoms (9/10 females, 56 years, range 43-65), who did not participate to any rehabilitation protocol. Cognitive performance was assessed with the Trail Making Test (TMT-A and -B) and Frontal Assessment Battery (FAB), and cardiovascular and muscular fatigue were assessed with the fatigue severity scale (FSS), six-minute walking test and handgrip endurance. Finally, transcranial magnetic stimulation (TMS) investigated cortical excitability.

RESULTS

The mixed-factors analysis of variance found a significant interaction effect only in cognitive performance evaluation, suggesting TMT-B execution time decreased (- 15.9 s, 95% CI 7.6-24.1, P = 0.001) and FAB score improved (1.88, 95% CI 2.93-0.82, P = 0.002) only in the physiotherapy group. For the remaining outcomes, no interaction effect was found, and most parameters similarly improved in the two groups.

CONCLUSION

The preliminary results from this study suggest that dual-task rehabilitation could be a feasible protocol to support cognitive symptoms recovery after COVID-19 and could be helpful in those individuals suffering from persisting and invalidating symptoms.

Definitions and measures of long COVID fatigue in adults: a scoping review protocol

OBJECTIVE

The aim of this scoping review is to investigate how fatigue is defined and measured in adults with long COVID.

INTRODUCTION

Following COVID-19 infection, 10% to 20% of individuals experience persisting symptoms for a minimum of 3 months; this is commonly known as long COVID. Fatigue is one of the most prevalent symptoms of long COVID, but there is currently no consistently applied definition of long COVID fatigue. To advance our understanding of long COVID fatigue, we must first identify the current definitions and measures being used to describe and mesure this condition.

INCLUSION CRITERIA

This review will consider published and unpublished studies involving adults (≥18 years) that define and/or measure long COVID fatigue. Papers using quantitative or qualitative designs will be included. Conference abstracts, editorials, and opinion papers will be excluded.

METHODS

Published studies from January 2020 onwards will be searched for across MEDLINE (Ovid), CINAHL (EBSCOhost), Embase (Ovid), Scopus, PsycINFO (Ovid), Web of Science Core Collection, Epistemonikos, and Cochrane Central Register of Controlled Trials (CENTRAL). Dimensions, Overton, and ProQuest Dissertations and Theses will be searched for unpublished literature. Eligible records will be de-duplicated, and 2 independent reviewers will carry out title, abstract, and full-text screening. A data extraction tool will be pilot tested on a small number of papers, then modified as necessary, with any modifications detailed in the scoping review. Findings will be presented in tables and charts, supported by a narrative summary.

REVIEW REGISTRATION

Open Science Framework https://osf.io/hnf8z.

[Interaction of somatic findings and psychiatric symptoms in COVID-19. A scoping review]

An infection with SARS-CoV‑2 can affect the central nervous system, leading to neurological as well as psychiatric symptoms. In this respect, mechanisms of inflammation seem to be of much greater importance than the virus itself. This paper deals with the possible contributions of organic changes to psychiatric symptomatology and deals especially with delirium, cognitive symptoms, depression, anxiety, posttraumatic stress disorder and psychosis. Processes of neuroinflammation with infection of capillary endothelial cells and activation of microglia and astrocytes releasing high amounts of cytokines seem to be of key importance in all kinds of disturbances. They can lead to damage in grey and white matter, impairment of cerebral metabolism and loss of connectivity. Such neuroimmunological processes have been described as a organic basis for many psychiatric disorders, as affective disorders, psychoses and dementia. As the activation of the glia cells can persist for a long time after the offending agent has been cleared, this can contribute to long term sequalae of the infection.

Long-term cognitive outcomes after surgery and anesthesia: what we find depends on where we look

Purpose of review

To review how anecdote and narrative medicine, primary cohort studies, epidemiological studies, and the dementia literature can be bridged to understand long-term postoperative cognitive decline.

Recent findings

Primary cohort studies have measured recoverable declines in memory and executive function after major surgery, but less-appreciated sources also offer critical insights. Anecdote reveals that functionally-impactful cognitive decline may persist after physical recovery in some patients despite modern medications and monitoring, and that physicians are unprepared to address patients' cognitive concerns. However, epidemiological studies reproducibly demonstrate that elective surgery has no, or a negligible, average impact on cognition in older patients. Cognitively provocative factors - like medical hospital admissions or health factors like diabetes and smoking - are common in late life, and surgery likely contributes minimally to long-term cognitive change for most patients.

Summary

Patients should be reassured that, while anecdotes of durable cognitive change after surgery are easily accessible, most patients experience cognitive recovery after major surgery. However, those who do not recover deserve characterization of their symptoms and investigation of modifiable causes to facilitate cognitive recovery.

Insights into attention and memory difficulties in post-COVID syndrome using standardized neuropsychological tests and experimental cognitive tasks

The COVID-19 pandemic has given rise to post-acute cognitive symptoms, often described as 'brain fog'. To comprehensively grasp the extent of these issues, we conducted a study integrating traditional neuropsychological assessments with experimental cognitive tasks targeting attention control, working memory, and long-term memory, three cognitive domains most commonly associated with 'brain fog'. We enrolled 33 post-COVID patients, all self-reporting cognitive difficulties, and a matched control group (N = 27) for cognitive and psychological assessments. Our findings revealed significant attention deficits in post-COVID patients across both neuropsychological measurements and experimental cognitive tasks, evidencing reduced performance in tasks involving interference resolution and selective and sustained attention. Mild executive function and naming impairments also emerged from the neuropsychological assessment. Notably, 61% of patients reported significant prospective memory failures in daily life, aligning with our recruitment focus. Furthermore, our patient group showed significant alterations in the psycho-affective domain, indicating a complex interplay between cognitive and psychological factors, which could point to a non-cognitive determinant of subjectively experienced cognitive changes following COVID-19. In summary, our study offers valuable insights into attention challenges faced by individuals recovering from COVID-19, stressing the importance of comprehensive cognitive and psycho-affective evaluations for supporting post-COVID individuals.

Applying Lessons From Rheumatology to Better Understand Long COVID

Long COVID can sometimes be attributed to organ damage and well-characterized pathophysiology, but more often there is no evidence of organ damage or abnormal biomarkers. This is most evident in patients with mild to moderate initial SARS-CoV-2 infection who were not hospitalized. Their persistent symptoms are strikingly similar to those of fibromyalgia and myalgic encephalomyelitis/chronic fatigue syndrome, including fatigue, post-exertional malaise, myalgias/arthralgias, and sleep and cognitive disturbances in 50% to 100% of cases. Analogous pathophysiologic pathways in fibromyalgia (FM), myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), and long COVID include host-microbial interactions in the absence of direct tissue invasion and absence of systemic autoimmunity, with evidence for immune dysregulation as well as autonomic, peripheral, and central nervous system dysfunction. Current treatment of long COVID has been based on multidisciplinary management recommended for FM and ME/CFS and has been formalized and made widely available by funding for nationwide long COVID clinics. Long COVID and its treatment should be distinguished by the presence or absence of organ damage. The acknowledged role of patient engagement in research and open dialogue regarding work and disability noted in long COVID may have meaningful impact on patients with FM and ME/CFS. Hopefully, advances in basic long COVID research will aid in understanding FM and ME/CFS, and rheumatologists should thus be involved in such research and patient care.

SARS-CoV-2 Causes Brain Damage: Therapeutic Intervention with AZD8797

Elevated CX3CL1 is associated with severe COVID-19 and neurologic symptoms. We aimed to investigate the potential protective effects of selective CX3CR1 antagonist AZD8797 on SARS-CoV-2-induced neuronal damage, and to identify the underlying mechanisms. K18-hACE2 transgenic mice (n = 37) were randomly divided into control groups and SARS-CoV-2 groups, with and without intraperitoneal administration of vehicle or AZD8797 (2.5 mg/mL/day), following exposure to either a single dose of SARS-CoV-2 inhalation or no exposure. Object recognition and hole board tests were performed to assess memory function. Postinfection 8 days, brain tissues were analyzed for histopathological changes, viral, glial, apoptotic, and other immunohistochemical markers, along with measuring malondialdehyde, glutathione, and myeloperoxidase activities. Serum samples were analyzed for proinflammatory cytokines. The SARS-CoV-2 group showed significant weight loss, neuronal damage, oxidative stress, and impaired object recognition memory, while AZD8797 treatment mitigated some of these effects, especially in weight, apoptosis, glutathione, and MCP-1. Histopathological analyses supported the protective effects of AZD8797 against SARS-CoV-2-induced damage. The CX3CL1-CX3CR1 signaling pathway could offer a promising target for reducing SARS-CoV-2's neurological impact, but additional research is needed to confirm these findings in combination with other therapies and assess the clinical significance.

Neuropsychological Profile of Hospitalized Patients Due to COVID-19: Clinical and Inflammatory Correlates

OBJECTIVES

In the present study, we investigated the pattern of cognitive difficulties in hospitalized patients due to COVID-19 and its relation with the clinical features of the disease.

METHOD

Forty hospitalized patients with COVID-19 [mean age: 46.98 years (SD = 9.30); mean years of education: 13.65 (SD = 2.07) and 40 sex-, age- and education-matched healthy controls completed a set of neuropsychological measures administered by telephone. Participants' premorbid intellectual skills and patients' anxiety and depressive symptoms were also evaluated. The association of COVID-19-related biomarkers [oxygen saturation (SpO2), C-reactive protein (CRP), D-dimer and ferritin levels] with neuropsychological performances was examined with a series of hierarchical multiple linear regression analyses, after controlling for demographic and clinical characteristics, psychological distress and premorbid intellectual skills.

RESULTS

Patients performed worse than healthy participants on measures of verbal memory, attention and working memory. SpO2 levels were associated with patients' performance on verbal and working memory, whereas CRP levels were associated with performance on verbal memory, abstract reasoning and verbal fluency, after controlling for demographic and clinical characteristics. Ferritin levels predicted performance on the verbal fluency test, whereas D-dimer levels did not predict any of the neuropsychological measures.

CONCLUSIONS

Cognitive difficulties in verbal memory, attention and working memory were noted in patients with COVID-19. Markers of hyperinflammation predicted patients' performance above and beyond demographic characteristics, duration of symptoms, length of hospitalization and psychological distress.

Five cluster classifications of long COVID and their background factors: A cross-sectional study in Japan

PURPOSE

The long-term symptoms of coronavirus disease 2019 (COVID-19), i.e., long COVID, have drawn research attention. Evaluating its subjective symptoms is difficult, and no established pathophysiology or treatment exists. Although there are several reports of long COVID classifications, there are no reports comparing classifications that include patient characteristics, such as autonomic dysfunction and work status. We aimed to classify patients into clusters based on their subjective symptoms during their first outpatient visit and evaluate their background for these clusters.

METHODS

Included patients visited our outpatient clinic between January 18, 2021, and May 30, 2022. They were aged ≥ 15 years and confirmed to have SARS-CoV-2 infection and residual symptoms lasting at least 2 months post-infection. Patients were evaluated using a 3-point scale for 23 symptoms and classified into five clusters (1. fatigue only; 2. fatigue, dyspnea, chest pain, palpitations, and forgetfulness; 3. fatigue, headache, insomnia, anxiety, motivation loss, low mood, and forgetfulness; 4. hair loss; and 5. taste and smell disorders) using CLUSTER. For continuous variables, each cluster was compared using the Kruskal-Wallis test. Multiple comparison tests were performed using the Dunn's test for significant results. For nominal variables, a Chi-square test was performed; for significant results, a residual analysis was conducted with the adjusted residuals.

RESULTS

Compared to patients in other cluster categories, those in cluster categories 2 and 3 had higher proportions of autonomic nervous system disorders and leaves of absence, respectively.

CONCLUSIONS

Long COVID cluster classification provided an overall assessment of COVID-19. Different treatment strategies must be used based on physical and psychiatric symptoms and employment factors.

Epidemiology of neurocognitive disorders in adults from urban-marginalized areas: a door-to-door population-based study in Puente Piedra, Lima, Peru

Background

In Latin America (LA), the prevalence of dementia is expected to triple to 150 million people by 2050. The 2020 Lancet Commission report identified several modifiable dementia risk factors, yet few social and environmental factors, most relevant to vulnerable regions of LA, were highlighted in this report. We sought to assess the epidemiology of neurocognitive disorders (NCD) in Puente Piedra, one of the most socially and economically vulnerable districts of Lima, the capital of Peru.

Methodology

This was a cross-sectional door-to-door observational study that used two-stage household sampling. One young adult (30-59 years) and one older adult (>60 years) per household were enrolled. We collected demographic, clinical, and neurocognitive data. Addenbrooke's Cognitive Examination (young adults) and the RUDAS-PE (older adults) were used, classifying participants as cognitively normal, possible mild NCD, or possible major NCD.

Results

We enrolled 247 participants (median age 46 years; 67% female). One-fourth had not completed secondary school and more than 50% completed only secondary school. Most participants were housewives (46%) and 21% did not have health insurance. The overall prevalence of possible NCD was 30% (25.6 and 41.8% among younger adults and older adults, respectively). Among younger adults, those ages 55-59 years more frequently had NCD (70%) compared to younger age ranges. Among older adults, only 3 subjects (4.5%) had major NCD.

Conclusion

We found a high frequency of possible NCDs in a socially and economically vulnerable community in Lima, Peru, with younger adults showing levels of NCD higher than expected. Our findings support the need for health systems to incorporate cognitive screenings programs for NCD in younger ages. Future research on NCD would include younger populations, particularly in vulnerable communities.

Intrinsic factors behind long-COVID: II. SARS-CoV-2, extracellular vesicles, and neurological disorders

With the decline in the number of new Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infections, the World Health Organization announced the end of the SARS-CoV-2 pandemic. However, the repercussions of this viral pandemic may remain with us for a longer period of time, as it has remodeled the lives of humankind in many ways, including social and economic. Of course, its most important repercussions remain on the human health level. Long-coronavirus disease (COVID) or post-COVID is a state for which we do not have a concrete definition, a specific international classification of diseases Code, clear diagnostic tools, or well-known effective cures as of yet. In this second article from the Intrinsic Factors behind long-COVID Series, we try to link long-COVID symptoms with their causes, starting from the nervous system. Extracellular vesicles (ECVs) play very complex and ramified roles in the bodies of both healthy and not-healthy individuals. ECVs may facilitate the entry of many bioactive molecules and pathogens into the tissues and cells of the nervous system across the blood-brain barrier. Based on the size, quantity, and quality of their cargo, ECVs are directly proportional to the pathological condition and its severity through intertwined mechanisms that evoke inflammatory immune responses typically accompanied by pathological symptoms over variable time periods according to the type of these symptoms.

A hypoarousal model of neurological post-COVID syndrome: the relation between mental fatigue, the level of central nervous activation and cognitive processing speed

BACKGROUND

Knowledge on the nature of post-COVID neurological sequelae often manifesting as cognitive dysfunction and fatigue is still unsatisfactory.

OBJECTIVES

We assumed that cognitive dysfunction and fatigue in post-COVID syndrome are critically linked via hypoarousal of the brain. Thus, we assessed whether tonic alertness as a neurocognitive index of arousal is reduced in these patients and how this relates to the level of central nervous activation and subjective mental fatigue as further indices of arousal.

METHODS

40 post-COVID patients with subjective cognitive dysfunction and 40 matched healthy controls underwent a whole-report paradigm of briefly presented letter arrays. Based on report performance and computational modelling according to the theory of visual attention, the parameter visual processing speed (VPS) was quantified as a proxy of tonic alertness. Pupillary unrest was assessed as a measure of central nervous activation. The Fatigue Assessment Scale was applied to assess subjective mental fatigue using the corresponding subscale.

RESULTS

VPS was reduced in post-COVID patients compared to controls (p = 0.005). In these patients, pupillary unrest (p = 0.029) and mental fatigue (p = 0.001) predicted VPS, explaining 34% of the variance and yielding a large effect with f2 = 0.51.

CONCLUSION

In post-COVID patients with subjective cognitive dysfunction, hypoarousal of the brain is reflected in decreased processing speed which is explained by a reduced level of central nervous activation and a higher level of mental fatigue. In turn, reduced processing speed objectifies mental fatigue as a core subjective clinical complaint in post-COVID patients.

Virtual reality for assessing stereopsis performance and eye characteristics in Post-COVID

In 2019, we faced a pandemic due to the coronavirus disease (COVID-19), with millions of confirmed cases and reported deaths. Even in recovered patients, symptoms can be persistent over weeks, termed Post-COVID. In addition to common symptoms of fatigue, muscle weakness, and cognitive impairments, visual impairments have been reported. Automatic classification of COVID and Post-COVID is researched based on blood samples and radiation-based procedures, among others. However, a symptom-oriented assessment for visual impairments is still missing. Thus, we propose a Virtual Reality environment in which stereoscopic stimuli are displayed to test the patient's stereopsis performance. While performing the visual tasks, the eyes' gaze and pupil diameter are recorded. We collected data from 15 controls and 20 Post-COVID patients in a study. Therefrom, we extracted features of three main data groups, stereopsis performance, pupil diameter, and gaze behavior, and trained various classifiers. The Random Forest classifier achieved the best result with 71% accuracy. The recorded data support the classification result showing worse stereopsis performance and eye movement alterations in Post-COVID. There are limitations in the study design, comprising a small sample size and the use of an eye tracking system.

Long COVID, the Brain, Nerves, and Cognitive Function

SARS-CoV-2, a single-stranded RNA coronavirus, causes an illness known as coronavirus disease 2019 (COVID-19). Long-term complications are an increasing issue in patients who have been infected with COVID-19 and may be a result of viral-associated systemic and central nervous system inflammation or may arise from a virus-induced hypercoagulable state. COVID-19 may incite changes in brain function with a wide range of lingering symptoms. Patients often experience fatigue and may note brain fog, sensorimotor symptoms, and sleep disturbances. Prolonged neurological and neuropsychiatric symptoms are prevalent and can interfere substantially in everyday life, leading to a massive public health concern. The mechanistic pathways by which SARS-CoV-2 infection causes neurological sequelae are an important subject of ongoing research. Inflammation- induced blood-brain barrier permeability or viral neuro-invasion and direct nerve damage may be involved. Though the mechanisms are uncertain, the resulting symptoms have been documented from numerous patient reports and studies. This review examines the constellation and spectrum of nervous system symptoms seen in long COVID and incorporates information on the prevalence of these symptoms, contributing factors, and typical course. Although treatment options are generally lacking, potential therapeutic approaches for alleviating symptoms and improving quality of life are explored.

Prevalence of swallow, communication, voice and cognitive compromise following hospitalisation for COVID-19: the PHOSP-COVID analysis

OBJECTIVE

Identify prevalence of self-reported swallow, communication, voice and cognitive compromise following hospitalisation for COVID-19.

DESIGN

Multicentre prospective observational cohort study using questionnaire data at visit 1 (2-7 months post discharge) and visit 2 (10-14 months post discharge) from hospitalised patients in the UK. Lasso logistic regression analysis was undertaken to identify associations.

SETTING

64 UK acute hospital Trusts.

PARTICIPANTS

Adults aged >18 years, discharged from an admissions unit or ward at a UK hospital with COVID-19.

MAIN OUTCOME MEASURES

Self-reported swallow, communication, voice and cognitive compromise.

RESULTS

Compromised swallowing post intensive care unit (post-ICU) admission was reported in 20% (188/955); 60% with swallow problems received invasive mechanical ventilation and were more likely to have undergone proning (p=0.039). Voice problems were reported in 34% (319/946) post-ICU admission who were more likely to have received invasive (p<0.001) or non-invasive ventilation (p=0.001) and to have been proned (p<0.001). Communication compromise was reported in 23% (527/2275) univariable analysis identified associations with younger age (p<0.001), female sex (p<0.001), social deprivation (p<0.001) and being a healthcare worker (p=0.010). Cognitive issues were reported by 70% (1598/2275), consistent at both visits, at visit 1 respondents were more likely to have higher baseline comorbidities and at visit 2 were associated with greater social deprivation (p<0.001).

CONCLUSION

Swallow, communication, voice and cognitive problems were prevalent post hospitalisation for COVID-19, alongside whole system compromise including reduced mobility and overall health scores. Research and testing of rehabilitation interventions are required at pace to explore these issues.

Post-acute (long) COVID-19 quality of life: validation of the German version of (PAC19QoL) instrument

Purpose

The aim of our study was to validate a German translation of the post-acute (long) COVID-19 quality of life (PAC-19QoL) instrument among German patients with long COVID-19 syndrome.

Patients and methods

The PAC-19QoL instrument was translated into the German language and administrated to patients with long COVID-19 syndrome. Cronbach's alpha coefficient was used to analyze the internal consistency of the instrument. Construction validity was evaluated by using Pearson's correlation coefficient and Spearman's rank correlation. Scores of patients and controls were compared using the Mann-Whitney U-test.

Results

A total of 45 asymptomatic and 41 symptomatic participants were included. In total, 41 patients with long COVID-19 syndrome completed the PAC-19QoL and EQ-5D-5L questionnaires. PAC-19QoL domain scores were significantly different between symptomatic and asymptomatic participants. All items achieved a Cronbach's alpha >0.7. There was a significant correlation between all domains on the test (p < 0.001), with the highest correlation between total (r = 0.994) and domain 1 (r = 0.991). Spearman's rank correlation analysis confirmed that the instrument items correlated with the objective PAC-19QoL examination findings.

Conclusion

The German version of the instrument is valid and reliable and can be a suitable tool for research and daily clinical practice among patients with long COVID-19 syndrome.

Olfaction and neurocognition after COVID-19: a scoping review

Introduction

COVID-19 induces both acute and chronic neurological changes. Existing evidence suggests that chemosensory changes, particularly olfactory loss, may reflect central neurological dysfunction in neurodegenerative diseases and mark progression from mild cognitive impairment to Alzheimer's. This scoping review summarizes the available literature to evaluate the relationship between neurocognition and olfaction in young to middle-aged adults with minimal comorbidities following COVID-19 infection.

Methods

A literature search of PubMed, Ovid Embase, Web of Science, and Cochrane Library was conducted. Studies underwent title/abstract and full text screening by two reviewers, with a third reviewer resolving any conflicts. Remaining studies underwent data extraction.

Results

Seventeen studies were eligible for data extraction after the review process, where 12 studies found significantly poorer cognition in those suffering from olfactory dysfunction, four studies showed no association between cognition and olfaction, and one study reported lower anosmia prevalence among patients with cognitive impairment.

Conclusion

The majority of studies in this review find that olfactory dysfunction is associated with poorer cognition. More rigorous studies are needed to further elucidate the relationship between olfaction and cognition after COVID-19.

ME/CFS and Long COVID share similar symptoms and biological abnormalities: road map to the literature

Some patients remain unwell for months after "recovering" from acute COVID-19. They develop persistent fatigue, cognitive problems, headaches, disrupted sleep, myalgias and arthralgias, post-exertional malaise, orthostatic intolerance and other symptoms that greatly interfere with their ability to function and that can leave some people housebound and disabled. The illness (Long COVID) is similar to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) as well as to persisting illnesses that can follow a wide variety of other infectious agents and following major traumatic injury. Together, these illnesses are projected to cost the U.S. trillions of dollars. In this review, we first compare the symptoms of ME/CFS and Long COVID, noting the considerable similarities and the few differences. We then compare in extensive detail the underlying pathophysiology of these two conditions, focusing on abnormalities of the central and autonomic nervous system, lungs, heart, vasculature, immune system, gut microbiome, energy metabolism and redox balance. This comparison highlights how strong the evidence is for each abnormality, in each illness, and helps to set priorities for future investigation. The review provides a current road map to the extensive literature on the underlying biology of both illnesses.

The Impact of COVID-19 Lockdown Measures and COVID-19 Infection on Cognitive Functions: A Review in Healthy and Neurological Populations

The COVID-19 pandemic severely affected people's mental health all over the world. This review aims to present a comprehensive overview of the literature related to the effects of COVID-19 lockdown measures and COVID-19 infection on cognitive functioning in both healthy people and people with neurological conditions by considering only standardized tests. We performed a narrative review of the literature via two databases, PUBMED and SCOPUS, from December 2019 to December 2022. In total, 62 out of 1356 articles were selected and organized into three time periods: short-term (1-4 months), medium-term (5-8 months), and long-term (9-12 months), according to the time in which the tests were performed. Regardless of the time period, most studies showed a general worsening in cognitive performance in people with neurological conditions due to COVID-19 lockdown measures and in healthy individuals recovered from COVID-19 infection. Our review is the first to highlight the importance of considering standardized tests as reliable measures to quantify the presence of cognitive deficits due to COVID-19. Indeed, we believe that they provide an objective measure of the cognitive difficulties encountered in the different populations, while allowing clinicians to plan rehabilitation treatments that can be of great help to many patients who still, nowadays, experience post-COVID-19 symptoms.

Validation of the Slovakian Version of the "Post‑acute (Long) COVID‑19 Quality of Life Instrument" and Pilot Study

Purpose

The aim of our study was to validate a Slovakian translation of the PAC‑19QoL instrument among Slovakian patients with post COVID-19 syndrome.

Patients and Methods

The PAC-19QoL instrument was translated into the Slovakian language and administrated to patients with post COVID-19 syndrome. Cronbach's alpha coefficient was used to analyse the internal consistency of the instrument. Construction validity was evaluated by using Pearson's correlation coefficient and Spearman's rank correlation. Scores of patients and controls were compared using Mann-Whitney U-test.

Results

Forty-five asymptomatic and forty-one symptomatic participants were included. Forty-one patients with post COVID-19 syndrome completed the PAC-19QoL and EQ-5D-5L questionnaires. PAC-19QoL domain scores were significantly different between symptomatic and asymptomatic participants. All items achieved a Cronbach alpha greater than 0.7. There was a significant correlation between all domains on the test (p < 0.001), with the highest correlation of Total (r = 0.994) and Domain 1 (r = 0.991). Spearman's rank correlation analysis confirmed that the instrument items correlated with the objective PAC-19QoL examination findings.

Conclusion

The Slovakian version of the instrument is valid, reliable and can be a suitable tool for research and daily clinical practice among patients with post COVID-19 syndrome.

Post-COVID-19 human memory impairment: A PRISMA-based systematic review of evidence from brain imaging studies

Many people with coronavirus disease 2019 (COVID-19) report varying degrees of memory impairment. Neuroimaging techniques such as MRI and PET have been utilized to shed light on how COVID-19 affects brain function in humans, including memory dysfunction. In this PRISMA-based systematic review, we compared and summarized the current literature looking at the relationship between COVID-19-induced neuropathological changes by neuroimaging scans and memory symptoms experienced by patients who recovered from COVID-19. Overall, this review suggests a correlational trend between structural abnormalities (e.g., cortical atrophy and white matter hyperintensities) or functional abnormalities (e.g., hypometabolism) in a wide range of brain regions (particularly in the frontal, parietal and temporal regions) and memory impairments in COVID-19 survivors, although a causal relationship between them remains elusive in the absence of sufficient caution. Further longitudinal investigations, particularly controlled studies combined with correlational analyses, are needed to provide additional evidence.

Psychological and Cognitive Effects of Long COVID: A Narrative Review Focusing on the Assessment and Rehabilitative Approach

Long COVID is a clinical syndrome characterized by profound fatigue, neurocognitive difficulties, muscle pain, weakness, and depression, lasting beyond the 3–12 weeks following infection with SARS-CoV-2. Among the symptoms, neurocognitive and psychiatric sequelae, including attention and memory alterations, as well as anxiety and depression symptoms, have become major targets of current healthcare providers given the significant public health impact. In this context, assessment tools play a crucial role in the early screening of cognitive alterations due to Long COVID. Among others, the general cognitive assessment tools, such as the Montreal Cognitive assessment, and more specific ones, including the State Trait Inventory of Cognitive Fatigue and the Digit Span, may be of help in investigating the main neurocognitive alterations. Moreover, appropriate neurorehabilitative programs using specific methods and techniques (conventional and/or advanced) through a multidisciplinary team are required to treat COVID-19-related cognitive and behavioral abnormalities. In this narrative review, we sought to describe the main neurocognitive and psychiatric symptoms as well as to provide some clinical advice for the assessment and treatment of Long COVID.

The reception of public health messages during the COVID-19 pandemic

Understanding the reception of public health messages in public-facing communications is of key importance to health agencies in managing crises, pandemics, and other health threats. Established public health communications strategies including self-efficacy messaging, fear appeals, and moralising messaging were all used during the Coronavirus pandemic. We explore the reception of public health messages to understand the efficacy of these established messaging strategies in the COVID-19 context. Taking a community-focussed approach, we combine a corpus linguistic analysis with methods of wider engagement, namely, a public survey and interactions with a Public Involvement Panel to analyse this type of real-world public health discourse.

Our findings indicate that effective health messaging content provides manageable instructions, which inspire public confidence that following the guidance is worthwhile. Messaging that appeals to the audience's morals or fears in order to provide a rationale for compliance can be polarising and divisive, producing a strongly negative emotional response from the public and potentially undermining social cohesion. Provenance of the messaging alongside text-external political factors also have an influence on messaging uptake. In addition, our findings highlight key differences in messaging uptake by audience age, which demonstrates the importance of tailored communications and the need to seek public feedback to test the efficacy of messaging with the relevant demographics. Our study illustrates the value of corpus linguistics to public health agencies and health communications professionals, and we share our recommendations for improving the public health messaging both in the context of the ongoing pandemic and for future novel and re-emerging infectious disease outbreaks.

Post-acute sequelae of COVID-19 symptom phenotypes and therapeutic strategies: A prospective, observational study

BACKGROUND

Post-acute sequelae of COVID-19 (PASC) includes a heterogeneous group of patients with variable symptomatology, who may respond to different therapeutic interventions. Identifying phenotypes of PASC and therapeutic strategies for different subgroups would be a major step forward in management.

METHODS

In a prospective cohort study of patients hospitalized with COVID-19, 12-month symptoms and quantitative outcome metrics were collected. Unsupervised hierarchical cluster analyses were performed to identify patients with: (1) similar symptoms lasting ≥4 weeks after acute SARS-CoV-2 infection, and (2) similar therapeutic interventions. Logistic regression analyses were used to evaluate the association of these symptom and therapy clusters with quantitative 12-month outcome metrics (modified Rankin Scale, Barthel Index, NIH NeuroQoL).

RESULTS

Among 242 patients, 122 (50%) reported ≥1 PASC symptom (median 3, IQR 1-5) lasting a median of 12-months (range 1-15) post-COVID diagnosis. Cluster analysis generated three symptom groups: Cluster1 had few symptoms (most commonly headache); Cluster2 had many symptoms including high levels of anxiety and depression; and Cluster3 primarily included shortness of breath, headache and cognitive symptoms. Cluster1 received few therapeutic interventions (OR 2.6, 95% CI 1.1-5.9), Cluster2 received several interventions, including antidepressants, anti-anxiety medications and psychological therapy (OR 15.7, 95% CI 4.1-59.7) and Cluster3 primarily received physical and occupational therapy (OR 3.1, 95%CI 1.3-7.1). The most severely affected patients (Symptom Cluster 2) had higher rates of disability (worse modified Rankin scores), worse NeuroQoL measures of anxiety, depression, fatigue and sleep disorder, and a higher number of stressors (all P<0.05). 100% of those who received a treatment strategy that included psychiatric therapies reported symptom improvement, compared to 97% who received primarily physical/occupational therapy, and 83% who received few interventions (P = 0.042).

CONCLUSIONS

We identified three clinically relevant PASC symptom-based phenotypes, which received different therapeutic interventions with varying response rates. These data may be helpful in tailoring individual treatment programs.