Comparative imaging study of patients with persistent olfactory dysfunction due to mild COVID-19 using structural and functional MRI.

INTRODUCTION: Persistent post-COVID olfactory dysfunction continues to be studied due to the controversy in its pathophysiology and neuroimaging. MATERIALS AND METHODS: The patients had confirmed mild COVID-19 infection with olfactory dysfunction of more than one month of evolution and they were compared to controls with normal olfaction, assessed using the Sniffin' Sticks Olfactory Test and underwent brain, magnetic resonance imaging (MRI) of the olfactory bulb and olfactory function. RESULTS: A total of 8 patients and 2 controls participated. The average age of the patients was 34.5 years (SD 8.5), and that of the controls was 28.5 (SD 2.1). The average score in the patients' olfactory test was 7.9 points (SD 2.2). In brain and olfactory bulb MRI tests, no morphological differences were found. When evaluated by functional MRI, none of the patients activated the entorhinal area in comparison to the controls, who did show activation at this level. Activation of secondary olfactory areas in cases and controls were as follows: orbitofrontal (25% vs 100%), basal ganglia (25% vs 50%) and insula (38% vs 0%) respectively. CONCLUSIONS: There were no observed morphological changes in the brain MRI. Unlike the controls, none of the patients activated the entorhinal cortex in the olfactory functional MRI.

Cognitive and physical fatigue: the experience and consequences of 'brain fog' after Spontaneous Coronary Artery Dissection (SCAD), a qualitative study.

AIMS: Brain fog and fatigue are common issues after acute coronary syndrome. However, little is known about the nature and impact of these experiences in spontaneous coronary artery dissection (SCAD) survivors. The aims of this study were to understand the experiences of brain fog and the coping strategies used after SCAD. METHODS AND RESULTS: Participants were recruited from the Victor Chang Cardiac Research Institute Genetics Study database and were considered eligible if their event occurred within 12-months. Seven semi-structured online focus groups were conducted between December to January 2021-2022, with this study reporting findings related to brain fog and fatigue. Interviews were transcribed and thematically analysed using an iterative approach. Participants (N=30) were a mean age of 52.2 ((9.5) and mostly female (n=27, 90%). The overarching theme of brain fog after SCAD included four main themes: how brain fog is experienced, perceived causes, impacts, and how people cope. Experiences included memory lapses, difficulty concentrating and impaired judgement, and perceived causes included medication, fatigue and tiredness, and menopause and hormonal changes. Impacts of brain fog included rumination, changes in self-perception, disruption to hobbies/pastimes, and limitations at work. Coping mechanisms included setting reminders and expectations, being one's own advocate, lifestyle and self-determined medication adjustments, and support from peers. CONCLUSION: Brain fog is experienced by SCAD survivors and the impacts are varied and numerous, including capacity to work. SCAD survivors reported difficulty understanding causes and found their own path to coping. Recommendations for clinicians are provided.

Adaptation and Validation of the Turkish Version of the Brain Fog Scale.

Brain fog is a condition that is characterized by poor concentration, memory loss, decreased cognitive function, and mental fatigue. Although it is generally known as a long-term COVID-19 symptom, brain fog has also been reported to be caused by many other diseases. Thus, it is necessary to assess this condition in certain populations. This study aimed to evaluate the reliability and validity of the Brain Fog Scale in a Turkish population. We conducted the study in two phases. In a pilot study including 125 participants, we confirmed the suitability of the scale for validity analyses and then conducted exploratory (n = 230) and confirmatory factor analyses (n = 343). The Cronbach's alpha value of the 23-item Brain Fog Scale was 0.966. In addition, the 23-item and three-factor structure was confirmed as a result of the analyses. These three factors are mental fatigue, impaired cognitive acuity, and confusion. We also found that participants previously diagnosed with COVID-19 had higher brain fog scores. This finding indicates that brain fog is an important condition that can accompany COVID-19. Furthermore, this validated construct has an acceptable fit and is a valid and useful tool for the Turkish population.

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.

Cognitive impairment in long-COVID.

Background and purpose:

Long Covid is a complex con­dition characterised by symptoms that per­sist for weeks and months after the Co­vid infection, accompanied by cognitive im­pairment that negatively affects daily life. Understanding this complex condition is im­portant for the development of diagnostic and therapeutic strategies.

This article aims to provide a comprehensive overview of cognitive impairment in long-COVID, including its definition, symptoms, pathophysiology, risk factors, assessment tools, imaging abnormalities, potential biomarkers, management strategies, long-term outcomes, and future directions for research.

The search methodology used in this review aimed to include a wide range of research on cognitive impairment related to both COVID-19 and long-COVID. Systematic searches of PubMed and Google Scholar databases were conducted using a mixture of MeSH terms and keywords including ‘cognition’, ‘cognitive impairment’, ‘brain fog’, ‘COVID-19’ and ‘long-COVID’. The search was restricted to studies published in English between 1 January 2019 and 11 February 2024, which presented findings on neurological manifestations in human participants.

Long-COVID is characterized by persistent symptoms following COVID-19 infection, with cognitive impairment being a prominent feature. Symptoms include brain fog, difficulties with concentration, memory issues, and executive function deficits. Pa­tho­physiological mechanisms involve vi­ral persistence, immune responses, and vas­cular damage. Risk factors include age, pre-existing conditions, and disease seve­rity. Cognitive assessment tools such as the Montreal Cognitive Assessment (MoCA) are essential for diagnosis. Imaging studies, including MRI, PET, and SPECT, reveal structural and functional brain alterations. Potential biomarkers include C-reactive protein, interleukin-6, and neuron-specific enolase. Management strategies encompass cognitive rehabilitation, occupational therapy, medications, and lifestyle modifications.

Long-COVID poses a multifaceted challenge, and cognitive impairment significantly impacts patients’ lives. A multi­disciplinary approach, including cognitive rehabilitation and medication when appropriate, is essential for effective management. Future research should focus on validating biomarkers and understanding long-term cognitive outcomes.

Conclusion – Long-COVID is a global health concern, and cognitive impairment is a distressing symptom. While pharmacological interventions have potential, they require careful consideration. Continued research is crucial for improving the understanding and treatment of cognitive impairment in long-COVID.

Spontaneous recovery from post-COVID-19 brain fog.

Background: One-third of individuals who contract novel coronavirus disease 2019 (COVID-19) reportedly experience persistent symptoms, including respiratory issues, headache, dizziness, taste disorders, fatigue, and various psychiatric and neurological symptoms, known as post-acute sequelae of SARS-CoV-2. In this case report, we present a patient who became aware of brain fog, which is cognitive impairment, approximately 2 months after their COVID-19 symptoms had resolved, accompanied by anxiety and depression. Case Presentation: The patient, a 35-year-old Japanese man, was infected with COVID-19 and resumed work approximately 2 weeks later after symptoms improved. Approximately 1 month after returning to work, the patient's concentration became impaired and he started making noticeable errors at work. These symptoms did not improve, leading him to the outpatient clinic specializing in COVID-19 sequelae at our hospital. Here, he underwent blood tests, electroencephalography, and head magnetic resonance imaging, which did not reveal any abnormalities. Cognitive decline due to COVID-19 sequelae was therefore suspected, prompting his evaluation in our department approximately 5 months after his initial COVID-19 infection. Detailed cognitive function tests were performed. He was monitored without the use of medications, and his cognitive function gradually improved. Approximately 11 months after his initial COVID-19 infection, the same cognitive function tests were conducted again, because his subjective cognitive function symptoms had disappeared, and improvement was observed in many items. Conclusion: Since brain fog is a relatively common sequela, we emphasize the importance of keeping this in mind from the initial consultations and comparing results over time.

Clinical and CSF single-cell profiling of post-COVID-19 cognitive impairment.

Natural history and mechanisms for persistent cognitive symptoms ("brain fog") following acute and often mild COVID-19 are unknown. In a large prospective cohort of people who underwent testing a median of 9 months after acute COVID-19 in the New York City/New Jersey area, we found that cognitive dysfunction is common; is not influenced by mood, fatigue, or sleepiness; and is correlated with MRI changes in very few people. In a subgroup that underwent cerebrospinal fluid analysis, there are no changes related to Alzheimer's disease or neurodegeneration. Single-cell gene expression analysis in the cerebrospinal fluid shows findings consistent with monocyte recruitment, chemokine signaling, cellular stress, and suppressed interferon response-especially in myeloid cells. Longitudinal analysis shows slow recovery accompanied by key alterations in inflammatory genes and increased protein levels of CXCL8, CCL3L1, and sTREM2. These findings suggest that the prognosis for brain fog following COVID-19 correlates with myeloid-related chemokine and interferon-responsive genes.

Intervention modalities for brain fog caused by long-COVID: systematic review of the literature.

Individuals suffering from long-COVID can present with "brain fog", which is characterized by a range of cognitive impairments, such as confusion, short-term memory loss, and difficulty concentrating. To date, several potential interventions for brain fog have been considered. Notably, no systematic review has comprehensively discussed the impact of each intervention type on brain fog symptoms. We included studies on adult (aged > 18 years) individuals with proven long- COVID brain-fog symptoms from PubMed, MEDLINE, Central, Scopus, and Embase. A search limit was set for articles published between 01/2020 and 31/12/2023. We excluded studies lacking an objective assessment of brain fog symptoms and patients with preexisting neurological diseases that affected cognition before COVID-19 infection. This review provided relevant information from 17 studies. The rehabilitation studies utilized diverse approaches, leading to a range of outcomes in terms of the effectiveness of the interventions. Six studies described noninvasive brain stimulation, and all showed improvement in cognitive ability. Three studies described hyperbaric oxygen therapy, all of which showed improvements in cognitive assessment tests and brain perfusion. Two studies showed that the use of Palmitoylethanolamide and Luteolin (PEA-LUT) improved cognitive impairment. Noninvasive brain stimulation and hyperbaric oxygen therapy showed promising results in the treatment of brain fog symptoms caused by long-COVID, with improved perfusion and cortical excitability. Furthermore, both rehabilitation strategies and PEA-LUT administration have been associated with improvements in symptoms of brain fog. Future studies should explore combinations of interventions and include longer follow-up periods to assess the long-term effects of these treatments.

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.

The Contribution of Psychological Symptoms to Cognitive Difficulties in Youth With Postural Orthostatic Tachycardia Syndrome and Chronic Pain.

INTRODUCTION: Subjectively experienced cognitive difficulties are common in youth with postural orthostatic tachycardia syndrome. The pathophysiological and psychological contributions of these cognitive impairments remain unclear. METHOD: Participants were 96 adolescents and young adults diagnosed with postural orthostatic tachycardia syndrome and admitted to an intensive pain treatment program. Participants completed cognitive assessment and measures of postural orthostatic tachycardia syndrome symptoms, pain intensity, pain catastrophizing, anxiety, depression, and functional disability. RESULTS: Self-reported autonomic symptom intensity, but not severity of heart rate change, was associated with cognitive performance. Symptoms of depression were associated with decreases in most measures of cognitive functioning. Pain intensity, pain catastrophizing, and depression but not cognitive scores and physiological measures, were significant predictors of disability. CONCLUSION: Depression appears to be a significant contributor to the cognitive difficulties in youth with postural orthostatic tachycardia syndrome. These findings highlight the importance of assessing and treating affective symptoms in this population along with medical and lifestyle approaches to treating postural orthostatic tachycardia syndrome symptoms.

Characteristics of brain lesions found using MRI imaging in patients with post-COVID with signs of cognitive decline.

OBJECTIVE: Aim: To describe and evaluate abnormalities of the brain in post-COVID patients with neurologic symptoms and cognitive deficits using MRI imaging of the brain. PATIENTS AND METHODS: Materials and Methods: We included 21 patients with a previous positive PCR testing for SARS-CoV-2 and one or more of the following symptoms: memory and cognitive decline, dizziness, anxiety, depression, chronic headaches. All patients had MRI imaging done at onset of symptoms, but after at least 1 year after positive testing for COVID-19 based on the patient's previous medical history. RESULTS: Results: All of the patients complained of lack of concentration, forgetfulness, hard to process information. 15 patients suffered from confusion, 10 from anxiety. Of the 21 patients 14 had isolated chronic headaches, 3 had isolated dizziness, 4 patients had both symptoms upon inclusion. All patients underwent MRI imaging as a part of the diagnostic workup and had varying degrees of neurodegeneration. CONCLUSION: Conclusions: Our data correlates with existing research and shows tendency for cognitive decline in post-COVID patients. This provides groundwork for further research to determine correlation between acceleration of neurodegeneration and post-COVID.

Characterization of cognitive symptoms in post COVID-19 patients.

Cognitive symptoms (CS) belong to the most common manifestations of the Post COVID-19 (PC) condition. We sought to objectify CS in PC patients using routine diagnostic assessments: neurocognitive testing (NCT) and brain imaging (BI). Further, we investigated possible associations of CS with patient reported outcomes (PROs), and risk factors for developing CS. Clinical data and PROs of 315 PC patients were assessed at a mean of 6 months after SARS-CoV-2 infection. 231 (73.3%) patients reported any sort of CS. Among them, 78 underwent NCT and 55 received BI. In NCT, the cognitive domains most affected were the working memory, attention, and concentration. Nonetheless, pathological thresholds were exceeded only in few cases. Neurocognitive performance did not differ significantly between patients complaining of severe (n = 26) versus non-severe (n = 52) CS. BI findings were abnormal in 8 (14.5%) cases with CS but were most likely not related to PC. Patients reporting high severity of CS scored worse in the PHQ-9, FSS, WHOQOL-BREF, were more likely to report impaired sleep, and had a higher prevalence of psychiatric diagnoses. Overall, NCT could confirm mild impairment in some but not all PC patients with CS, while BI studies were abnormal in only few cases. CS severity did not affect NCT results, but severe CS were associated with symptoms of depression (PHQ-9), fatigue (FSS), reduced quality of life (WHOQOL-BREF) and higher prevalence of psychiatric illnesses. These findings support the importance of NCT, BI, and neuro-psychological assessment in the work-up of PC patients reporting CS. TRIAL REGISTRATION: Trial registration number and date of registration: DRKS00030974, 22 Dec 2022, retrospectively registered.

Efficacy of Original Neurofeedback Treatment Method for Brain Fog From COVID-19: A Case Report.

Brain fog is one of the most well-known sequelae of long COVID. It causes cognitive problems, mostly short-term memory disturbances, attention impairments, and problems with concentration. Although trials for treatment methods for brain fog have been carried out worldwide, effective methods have not yet been reported. Neurofeedback is effective for several common disorders and symptoms, including anxiety, depression, headaches, and pain. Neurofeedback is also reported to improve cognitive functions, such as processing speed and executive functions, including attention, planning, organization, problem-solving, and performance. Furthermore, neurofeedback is effective for "chemofog" and "chemobrain," which occur after chemotherapy and cause cognitive impairments in a similar manner to brain fog. However, there have been no reports of neurofeedback treatments for brain fog. Therefore, we have started to develop an original neurofeedback treatment method for brain fog using a Z-score neurofeedback technique. In this study, we present the first case report of a patient who has successfully recovered from brain fog via neurofeedback. Pain and psychological assessments revealed that the patient's pain improved and that the patient recovered from anxiety. Electroencephalograph data revealed several noble findings. C4 was thought to be the most affected site by brain fog, and this improved after treatment. The percentage increase at alpha wavelengths increased at almost all sites, and beta 1, beta 2, beta 3, and Hi beta decreased at almost all sites. The increased values at theta and alpha wavelengths after the 1st and 2nd sessions and the decreased values at higher beta wavelengths, such as beta 3 and Hi beta, were shown at all sessions.

Subdural effusion associated with COVID-19 encephalopathy: A case report.

BACKGROUND: The precise mechanism by which severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) impacts the central nervous system remains unclear, with manifestations spanning from mild symptoms (e.g., olfactory and gustatory deficits, hallucinations, and headache) to severe complications (e.g., stroke, seizures, encephalitis, and neurally demyelinating lesions). The occurrence of single-pass subdural effusion, as described below, is extremely rare. CASE SUMMARY: A 56-year-old male patient presented with left-sided limb weakness and slurred speech as predominant clinical symptoms. Through comprehensive imaging and diagnostic assessments, he was diagnosed with cerebral infarction complicated by hemorrhagic transformation affecting the right frontal, temporal, and parietal regions. In addition, an intracranial infection with SARS-CoV-2 was identified during the rehabilitation process; consequently, an idiopathic subdural effusion developed. Remarkably, the subdural effusion underwent absorption within 6 d, with no recurrence observed during the 3-month follow-up. CONCLUSION: Subdural effusion is a potentially rare intracranial complication associated with SARS-CoV-2 infection.

Pathophysiological Mechanisms in Long COVID: A Mixed Method Systematic Review.

INTRODUCTION: Long COVID (LC) is a global public health crisis affecting more than 70 million people. There is emerging evidence of different pathophysiological mechanisms driving the wide array of symptoms in LC. Understanding the relationships between mechanisms and symptoms helps in guiding clinical management and identifying potential treatment targets. METHODS: This was a mixed-methods systematic review with two stages: Stage one (Review 1) included only existing systematic reviews (meta-review) and Stage two (Review 2) was a review of all primary studies. The search strategy involved Medline, Embase, Emcare, and CINAHL databases to identify studies that described symptoms and pathophysiological mechanisms with statistical analysis and/or discussion of plausible causal relationships between mechanisms and symptoms. Only studies that included a control arm for comparison were included. Studies were assessed for quality using the National Heart, Lung, and Blood Institute quality assessment tools. RESULTS: 19 systematic reviews were included in Review 1 and 46 primary studies in Review 2. Overall, the quality of reporting across the studies included in this second review was moderate to poor. The pathophysiological mechanisms with strong evidence were immune system dysregulation, cerebral hypoperfusion, and impaired gas transfer in the lungs. Other mechanisms with moderate to weak evidence were endothelial damage and hypercoagulation, mast cell activation, and auto-immunity to vascular receptors. CONCLUSIONS: LC is a complex condition affecting multiple organs with diverse clinical presentations (or traits) underpinned by multiple pathophysiological mechanisms. A 'treatable trait' approach may help identify certain groups and target specific interventions. Future research must include understanding the response to intervention based on these mechanism-based traits.

The Fatigue and Altered Cognition Scale among SARS-CoV-2 Survivors: Psychometric Properties and Item Correlations with Depression and Anxiety Symptoms.

Background/Objectives: This study examined the psychometric properties of the Fatigue and Altered Cognition Scale (FACs) among adult COVID-19 survivors and its unique ability to assess symptomology not accounted for by measures of depression and anxiety. Methods: COVID-19 survivors completed an online survey that included the FACs, a measure of brain fog and central fatigue with 20 items rated on a digital-analog scale. Useable data from 559 participants were analyzed to test the two-factor structure of the FACs, test for measurement invariance by sex and device was used to complete the survey (hand-held, computer), and item correlations with symptoms of depression and anxiety were examined. Results: The two-factor structure of the FACs replicated, supporting the separate assessments of brain fog and fatigue, χ2(164) = 1028.363, p < 0.001, CFI = 0.934, TLI = 0.923, RMSEA = 0.097, SRMR = 0.053. The FACs exhibited invariance at the scalar level, indicating item and factor integrity regardless of sex and device type. Using a correlation > 0.70 as a criterion (i.e., indicating more than 50% shared variance between two items), items on the FACs (assessing fatigue and lack of energy) were highly correlated with feeling tired or having little energy on the depression measure. No other items correlated with any anxiety symptom larger than 0.70. Conclusions: The FACs appears to be a psychometrically sound and efficient measure for use with COVID-19 survivors, assessing symptoms of brain fog and central fatigue that are not attributable to symptoms assessed by established measures of depression and anxiety.

Development and validation of a brain fog scale for coeliac disease.

BACKGROUND: Brain fog is a subjective cognitive impairment commonly reported in coeliac disease. A standardised tool to define and assess it is an important unmet need. AIMS: To develop a patient-informed tool to assess brain fog in coeliac disease to support clinical care, research and drug development. METHODS: A pilot online study defined patient descriptors of brain fog. A second study evaluated the factor structure and performance of the scale across two-time points ('Now' and in the 'Past week'). One month later, participants were invited to repeat the study with two online cognitive processing tests, the Stroop task and the trail making test. RESULTS: Among adults with treated coeliac disease, 37 (91.9% F) participated in the pilot study and 510 (88.8% F) in the second study of whom 99 repeated the study 1 month later with 51 completing cognitive testing. The most common brain fog descriptors were 'difficulty focusing', 'difficulty thinking' and 'difficulty finding the right words and communicating'. The 12-item scale reflects 'cognitive impairment' and 'somatic and affective experience' and demonstrates strong psychometric properties. It tracked with patients report of brain fog being present or absent across two-time points. It did not significantly correlate with the cognitive tests. CONCLUSION: The brain fog assessment and severity scale is the first patient-informed clinical outcomes assessment tool measuring brain fog in coeliac disease. It is brief and validated for two time-based formats. Further research coupling it with biomarker discovery is needed to confirm its validity as a predictor of cognitive performance.

A pilot study to assess blood-brain barrier permeability in long COVID.

The etiology of brain fog associated with long COVID is not clear. Based on some preliminary work, disruption of the blood-brain barrier has been hypothesized, but has not been tested in patients with long COVID. In this case-control pilot study, we evaluated blood-brain barrier permeability in patients with long COVID and subjective memory loss or brain fog. We used 99 m Technetium diethylenetriaminepentaacetic acid single-photon emission computed tomography (SPECT) to measure blood-brain barrier permeability and a telephone assessment (T-cog) to measure cognitive function. The blood-brain barrier permeability was quantified via SPECT standard uptake value (SUV). We assessed the blood-brain barrier permeability in 14 long COVID patients and 10 control participants without subjective cognitive impairment or brain fog. Participants in the two groups were similar in age. The long COVID group had more comorbidities compared to the control group. There was no difference in the SUVs in the long COVID (0.22 ± 0.12) vs the control (0.17 ± 0.04) group. There was no difference in the T-cog results in the two groups either. We found no evidence of a difference in blood-brain permeability in patients with long COVID when compared to controls without a known history of COVID-19 infection. Larger studies are needed to confirm these findings.

Association between brain fog, cardiac injury, and quality of life at work after hospitalization due to COVID-19.

BACKGROUND: To evaluate incidence and search for possible predictors of brain fog and quality of life at work (QoL-W) among low-to-moderate risk subjects previously hospitalized due to COVID-19. MATERIAL AND METHODS: Participants aged ≥18 retrospectively reported 8 brain fog symptoms pre-COVID-19, at 0-4, 4-12 and >12 weeks post-infection via validated clinical questionnaire. The QoL-W was assessed with a 4-point Likert scale where 0, 1, 2, and 3 meant no, mild, moderate, and severe impairment in performing activities at work, respectively. Data on age, sex, comorbidities, and laboratory results (including first in-hospital high-sensitivity cardiac troponin I [hs-cTnI] measurement) were gathered. RESULTS: The study included 181 hospitalized subjects (age Me = 57 years), 37.02% women. Most had low disease severity (Modified Early Warning Score = 1, 77.90%) and low comorbidity (Charlson Comorbidity Index 0: 28.72%, 1-2: 34.09%), with no intensive care unit treatment needed. COVID-19 led to almost 3-fold increased brain fog symptoms, with incidence of 58.56%, 53.59%, and 49.17% within 4, 4-12, and >12 weeks, respectively (p < 0.001). First in-hospital hs-cTnI levels were 47.3% higher in participants who later presented with brain fog at median follow-up of 26.7 weeks since the diagnosis of the SARS-CoV-2 infection. Individuals who experienced at least one brain fog symptom at follow-up, had elevated hs-cTnI, less often presented with atrial fibrillation, and used anticoagulants during initial hospitalization due to COVID-19. The Hs-cTnI >11.90 ng/l predicted brain fog symptoms in multivariable model. COVID-19 was associated with 3.6­fold, 3.0­fold, and 2.4-fold QoL-W deterioration within 4, 4-12, and >12 weeks post-infection (p < 0.05). Subjects with QoL-W decline >12 weeks were younger, mostly women, had more brain fog symptoms, and higher platelet counts. Multivariable models with self-reported brain fog symptoms (responding coherently and recalling recent information), age, and sex exhibited good discriminatory power for QoL-W impairment (area under the receiver operating characteristic curve 0.846, 95% CI: 0.780-0.912). CONCLUSIONS: This study highlighted that in non-high-risk subjects hospitalized during the first 2 pandemic's waves: 1) brain fog was common, affecting nearly half of individuals, and impacting QoL-W >12 weeks after initial infection, 2) after 3 months of COVID-19 onset, the decline in QoL-W was primarily attributed to brain fog symptoms rather than demographic factors, health conditions, admission status, and laboratory findings, 3) components of brain fog, such as answering in an understandable way or recalling new information increased the likelihood of significantly lower QoL-W up to tenfold, 4) biochemical indicators, such as the first hs-cTnI level, might predict the risk of experiencing brain fog symptoms and indirectly decreased QoL-W >12 weeks after COVID-19 onset. Occupational medicine practitioners should pay particular attention to younger and female subjects after COVID-19 complaining of problems with answering questions in understandable way or recalling new information as they have an increased risk of QoL-W impairment. Med Pr Work Health Saf. 2024;75(1):3-17.

The knowns and unknowns of long COVID-19: from mechanisms to therapeutical approaches.

The coronavirus disease 2019 (COVID-19) pandemic caused by SARS-CoV-2 has been defined as the greatest global health and socioeconomic crisis of modern times. While most people recover after being infected with the virus, a significant proportion of them continue to experience health issues weeks, months and even years after acute infection with SARS-CoV-2. This persistence of clinical symptoms in infected individuals for at least three months after the onset of the disease or the emergence of new symptoms lasting more than two months, without any other explanation and alternative diagnosis have been named long COVID, long-haul COVID, post-COVID-19 conditions, chronic COVID, or post-acute sequelae of SARS-CoV-2 (PASC). Long COVID has been characterized as a constellation of symptoms and disorders that vary widely in their manifestations. Further, the mechanisms underlying long COVID are not fully understood, which hamper efficient treatment options. This review describes predictors and the most common symptoms related to long COVID's effects on the central and peripheral nervous system and other organs and tissues. Furthermore, the transcriptional markers, molecular signaling pathways and risk factors for long COVID, such as sex, age, pre-existing condition, hospitalization during acute phase of COVID-19, vaccination, and lifestyle are presented. Finally, recommendations for patient rehabilitation and disease management, as well as alternative therapeutical approaches to long COVID sequelae are discussed. Understanding the complexity of this disease, its symptoms across multiple organ systems and overlapping pathologies and its possible mechanisms are paramount in developing diagnostic tools and treatments.