Neuropsychological Predictors of Fatigue in Post-COVID Syndrome

Cognitive profile in multiple sclerosis and post-COVID condition: a comparative study using a unified taxonomy

Post-COVID condition (PCC) and multiple sclerosis (MS) share some clinical and demographic features, including cognitive symptoms and fatigue. Some pathophysiological mechanisms well-known in MS, such as autoimmunity, neuroinflammation and myelin damage, have also been implicated in PCC. In this study, we aimed to compare the cognitive phenotypes of two large cohorts of patients with PCC and MS, and to evaluate the relationship between fatigue and cognitive performance. Cross-sectional study including 218 patients with PCC and 218 with MS matched by age, sex, and years of education. Patients were evaluated with a comprehensive neuropsychological protocol and were categorized according to the International Classification of Cognitive Disorders system. Fatigue and depression were also assessed. Cognitive profiles of PCC and MS largely overlapped, with a greater impairment in episodic memory in MS, but with small effect sizes. The most salient deficits in both disorders were in attention and processing speed. The severity of fatigue was greater in patients with PCC. Still, the correlations between fatigue severity and neuropsychological tests were more prominent in the case of MS. There were no differences in the severity of depression among groups. Our study found similar cognitive profiles in PCC and MS. Fatigue was more severe in PCC, but was more associated with cognitive performance in MS. Further comparative studies addressing the mechanisms related to cognitive dysfunction and fatigue may be of interest to advance the knowledge of these disorders and develop new therapies.

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.

Special Issue "Post-COVID-19 Symptoms in Long-Haulers: Definition, Identification, Mechanisms, and Management"

The worldwide spread of coronavirus disease 2019 (COVID-19), a condition caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pathogen, led to the most unprecedented disease outbreak of this century, provoking around 770 million confirmed cases and nearly 7 million deaths globally [...].

Unraveling brain fog in post-COVID syndrome: Relationship between subjective cognitive complaints and cognitive function, fatigue, and neuropsychiatric symptoms

BACKGROUND AND PURPOSE

"Brain fog" is a frequent and disabling symptom that can occur after SARS-CoV-2 infection. However, its clinical characteristics and the relationships among brain fog and objective cognitive function, fatigue, and neuropsychiatric symptoms (depression, anxiety) are still unclear. In this study, we aimed to examine the characteristics of brain fog and to understand how fatigue, cognitive performance, and neuropsychiatric symptoms and the mutual relationships among these variables influence subjective cognitive complaints.

METHODS

A total of 170 patients with cognitive complaints in the context of post-COVID syndrome were evaluated using a comprehensive neuropsychological protocol. The FLEI scale was used to characterize subjective cognitive complaints. Correlation analysis, regression machine-learning algorithms, and mediation analysis were calculated.

RESULTS

Cognitive complaints were mainly attention and episodic memory symptoms, while executive functions (planning) issues were less often reported. The FLEI scale, a mental ability questionnaire, showed high correlations with a fatigue scale and moderate correlations with the Stroop test, and anxiety and depressive symptoms. Random forest algorithms showed an R2 value of 0.409 for the prediction of FLEI score, with several cognitive tests, fatigue and depression being the best variables used in the prediction. Mediation analysis showed that fatigue was the main mediator between objective and subjective cognition, while the effect of depression was indirect and mediated through fatigue.

CONCLUSIONS

Brain fog associated with COVID-19 is mainly characterized by attention and episodic memory, and fatigue, which is the main mediator between objective and subjective cognition. Our findings contribute to understanding the pathophysiology of brain fog and emphasize the need to unravel the main mechanisms underlying brain fog, considering several aspects.

The influence of physical fatigue on telephone-based neuropsychological test performance in COVID-19 survivors

Fatigue has been characterized as a post COVID-19 condition known to persist months after SARS-CoV-2 infection. COVID-19 has been reported to be associated with impaired cognitive function, including disorders in attention, memory, information processing, and executive functions. The objective of this study was to determine if post-COVID fatigue, manifested as tiredness while performing low-intensity physical activity, has a detrimental effect on neuropsychological performance, to achieve this, we randomly selected 20 participants with post-COVID fatigue and 20 SARS-CoV-2 negative age-matched controls from a database of 360 residents of Tijuana, Baja California in a cross-sectional study design. All 40 participants responded to a health survey, along with a neuropsychological assessment test via telephone call. Statistical analysis was performed using a multiple linear regression model including the following independent variables: study condition (post-COVID fatigue or negative control), sex, age, years of education, hypertension, asthma, administration of supplemental oxygen during COVID-19 recovery, and the hour at which the evaluation started. Significant regression analysis was obtained for all global parameters of the assessment, including BANFE-2 score (p = 0.021, R² Adj. = 0.263), NEUROPSI score (p = 0.008, R² Adj. = 0.319), and total errors (p = 0.021, R² Adj. = 0.263), with significant regression coefficients for study condition on two global parameters, BANFE-2 score (p = 0.028, β = - 0.371) and NEUROPSI score (p = 0.010, β = -0.428). These findings suggest that the presence of post-COVID fatigue is a factor associated with a decrease in neuropsychological performance.

Transcranial direct current stimulation for post-COVID fatigue: a randomized, double-blind, controlled pilot study

Fatigue is one of the most frequent and disabling symptoms of the post-COVID syndrome. In this study, we aimed to assess the effects of transcranial direct current stimulation on fatigue severity in a group of patients with post-COVID syndrome and chronic fatigue. We conducted a double-blind, parallel-group, sham-controlled study to evaluate the short-term effects of anodal transcranial direct current stimulation (2 mA, 20 min/day) on the left dorsolateral prefrontal cortex. The modified fatigue impact scale score was used as the primary endpoint. Secondary endpoints included cognition (Stroop test), depressive symptoms (Beck depression inventory) and quality of life (EuroQol-5D). Patients received eight sessions of transcranial direct current stimulation and were evaluated at baseline, immediately after the last session, and one month later. Forty-seven patients were enrolled (23 in the active treatment group and 24 in the sham treatment group); the mean age was 45.66 ± 9.49 years, and 37 (78.72%) were women. The mean progression time since the acute infection was 20.68 ± 6.34 months. Active transcranial direct current stimulation was associated with a statistically significant improvement in physical fatigue at the end of treatment and 1 month as compared with sham stimulation. No significant effect was detected for cognitive fatigue. In terms of secondary outcomes, active transcranial direct current stimulation was associated with an improvement in depressive symptoms at the end of treatment. The treatment had no effects on the quality of life. All the adverse events reported were mild and transient, with no differences between the active stimulation and sham stimulation groups. In conclusion, our results suggest that transcranial direct current stimulation on the dorsolateral prefrontal cortex may improve physical fatigue. Further studies are needed to confirm these findings and optimize stimulation protocols.

Fatigue and Cognitive Dysfunction Are Associated with Occupational Status in Post-COVID Syndrome

Post-COVID syndrome (PCS) is a medical condition characterized by the persistence of a wide range of symptoms after acute infection by SARS-CoV-2. The work capacity consequences of this disorder have scarcely been studied. We aimed to analyze the factors associated with occupational status in patients with PCS. This cross-sectional study involved 77 patients with PCS on active work before SARS-CoV-2 infection. Patients were evaluated 20.71 ± 6.50 months after clinical onset. We conducted a survey on occupational activity and cognitive and clinical symptoms. The association between occupational activity and fatigue, depression, anxiety, sleep quality, and cognitive testing was analyzed. Thirty-eight (49.4%) patients were working, and thirty-nine (50.6%) patients were not. Of those not working at the moment of the assessment, 36 (92.3%) patients were on sick leave. In 63 patients (81.8% of the sample), sick leave was needed at some point due to PCS. The mean duration of sick leave was 12.07 ± 8.07 months. According to the patient's perspective, the most disabling symptoms were cognitive complaints (46.8%) and fatigue (31.2%). Not working at the moment of the assessment was associated with higher levels of fatigue and lower cognitive performance in the Stroop test. No association was found between occupational status with depression and anxiety questionnaires. Our study found an influence of PCS on work capacity. Fatigue and cognitive issues were the most frequent symptoms associated with loss of work capacity.

Cross-sectional analysis of clinical aspects in patients with long-COVID and post-COVID syndrome

Objective

Regarding pathogenesis, clinical manifestations, at-risk individuals, and diagnostic methods for stratifying patients for therapeutic approaches, our understanding of post-COVID syndrome is limited. Here, we set out to assess sociodemographic and clinical aspects in patients with the long-COVID and post-COVID syndrome.

Methods

We performed a cross-sectional analysis of patients presenting at our specialized university hospital outpatient clinic. We assessed patients' clinical presentation, fatigue, symptoms of depression and anxiety, and impairment of smell.

Results

A total of 101 patients were included (73.3% female), of whom 78.2% had a mild course of COVID-19. At presentation, 93.1% suffered from fatigue, 82.2% from impaired concentration, and 79.2% from impaired memory, 53.5% had impaired sleep. The most common secondary diagnosis found in our cohort was thyroid disease. Fatigue analysis showed that 81.3% of female and 58.8% of male patients had severe combined fatigue. Female gender was an independent risk factor for severe fatigue (severe cognitive fatigue OR = 8.045, p = 0.010; severe motor fatigue OR = 7.698, p = 0.013). Males suffered from more depressive symptoms, which correlated positively with the duration of symptom onset. 70.3% of patients with anamnestic smell impairment had hyposmia, and 18.9% were anosmic.

Interpretation

Most long-COVID patients suffered from severe fatigue, with the female sex as an independent risk factor. Fatigue was not associated with symptoms of depression or anxiety. Patients with long-COVID symptoms should receive an interdisciplinary diagnostic and therapeutic approach depending on the clinical presentation.