Long Covid brain fog: a neuroinflammation phenomenon?

Characteristics of symptoms during athletes' COVID-19 infection and return to training: A descriptive study

This study aims to analyze the symptom characteristics and changes in symptoms upon returning to training among athletes infected with the novel corona virus disease 2019 (COVID-19). The findings provide recommendations for training and medical support for athletes after infection. In-depth analysis was conducted on symptom data from 221 athletes who tested positive for COVID-19 between December 2022 and January 2023. The data were collected during a sports performance recovery test series, which included 3 questionnaires assessing symptom occurrence and subjective severity during the infection and recovery periods. After the initial positive test, athletes took approximately 7 days to test negative. The main symptoms during infection were fever, dry cough, and fatigue, with occurrence rates exceeding or approaching 90% and fatigue symptoms being higher than moderate severity. Upon returning to training, the predominant symptoms were dry cough, fatigue, muscle soreness, and excessive sleepiness, with occurrence rates exceeding or approaching 50% and all symptoms being lower intensity than moderate. With the progression of training, the occurrence and severity of dry cough and excessive sleepiness decreased, while the occurrence of fatigue and muscle soreness remained relatively stable but with reduced intensity. Some less prevalent symptoms showed minimal changes. Athletes infected with the Omicron variant of COVID-19 primarily exhibit fever, dry cough, and fatigue, which typically turn negative after approximately 7 days. Upon returning to training, respiratory symptoms subside quickly, while persistent symptoms mainly consist of fatigue. Less prevalent symptoms may become prolonged if they fail to subside promptly.

Mitigating fatigue in long COVID patients with MYPplus: a clinical observation

PURPOSE

The COVID-19 pandemic has led to the emergence of a secondary public health crisis known as Long COVID. It is estimated that approximately 10% of individuals who contact COVID-19 develop Long COVID, with fatigue and brain fog being among the most commonly reported and debilitating symptoms. However, no standardized or effective treatments are currently available. This observational study aimed to evaluate the efficacy of MYPplus, an herbal formulation composed of Astragali Radix, Salviae Radix, and Aquilariae Lignum, in alleviating fatigue and brain fog in patients with Long COVID.

METHODS

Subjects with a score of 60 or higher on the Modified Korean version of the Chalder Fatigue scale (mKCFQ11) or a brain fog rating of 5 or higher on the visual analogue scale (VAS) took two capsules of MYPplus (500 mg per capsule) twice daily for 4 weeks. Changes in symptoms were assessed using the mKCFQ11, Multidimensional Fatigue Inventory (MFI-20), Fatigue VAS, Brain fog VAS, and overall quality of life using the Short-Form Health Survey (SF-12). Additionally, levels of three cytokines (TNF-α, TGF-β, IFN- γ) and cortisol were measured.

RESULTS

Fifty participants successfully completed the 4-week administration with MYPplus. At baseline, fatigue severity was 75.3 ± 10.9 in mKCFQ11, 70.9 ± 11.2 in MFI-20, 7.5 ± 1.2 in Fatigue VAS, 8.4 ± 1.1 in Brain fog VAS, and 45.3 ± 17.8 in SF-12. All parameters significantly improved (p < 0.01), with a decrease of 46% in mKCFQ11, 26% in MFI-20, 49% in Fatigue VAS, and 52% in Brain fog VAS, and an increase of 59% in SF-12, respectively. Unlikely others, the plasma level of TGF-β showed a declining pattern after MYPplus administration (from 765.0 ± 1759.7 to 243.9 ± 708.1 pg/mL, p = 0.07). No safety concerns were observed.

CONCLUSION

This pilot observational study suggests the clinical potential of MYPplus for managing patients with Long COVID, focusing on fatigue-related symptoms and quality of life. Further studies are required to confirm its efficacy and safety using large-scale randomized placebo-controlled trials in the future.

PROTOCOL REGISTRATION

This study has been retrospectively registered with the identifier number KCT0008948 on https://cris.nih.go.kr , as of 27/10/23.

Long COVID - a critical disruption of cholinergic neurotransmission?

BACKGROUND

Following the COVID-19 pandemic, there are many chronically ill Long COVID (LC) patients with different symptoms of varying degrees of severity. The pathological pathways of LC remain unclear until recently and make identification of path mechanisms and exploration of therapeutic options an urgent challenge. There is an apparent relationship between LC symptoms and impaired cholinergic neurotransmission.

METHODS

This paper reviews the current literature on the effects of blocked nicotinic acetylcholine receptors (nAChRs) on the main affected organ and cell systems and contrasts this with the unblocking effects of the alkaloid nicotine. In addition, mechanisms are presented that could explain the previously unexplained phenomenon of post-vaccination syndrome (PVS). The fact that not only SARS-CoV-2 but numerous other viruses can bind to nAChRs is discussed under the assumption that numerous other post-viral diseases and autoimmune diseases (ADs) may also be due to impaired cholinergic transmission. We also present a case report that demonstrates changes in cholinergic transmission, specifically, the availability of α4β2 nAChRs by using (-)-[18F]Flubatine whole-body positron emission tomography (PET) imaging of cholinergic dysfunction in a LC patient along with a significant neurological improvement before and after low-dose transcutaneous nicotine (LDTN) administration. Lastly, a descriptive analysis and evaluation were conducted on the results of a survey involving 231 users of LDTN.

RESULTS

A substantial body of research has emerged that offers a compelling explanation for the phenomenon of LC, suggesting that it can be plausibly explained because of impaired nAChR function in the human body. Following a ten-day course of transcutaneous nicotine administration, no enduring neuropathological manifestations were observed in the patient. This observation was accompanied by a significant increase in the number of free ligand binding sites (LBS) of nAChRs, as determined by (-)-[18F]Flubatine PET imaging. The analysis of the survey shows that the majority of patients (73.5%) report a significant improvement in the symptoms of their LC/MEF/CFS disease as a result of LDTN.

CONCLUSIONS

In conclusion, based on current knowledge, LDTN appears to be a promising and safe procedure to relieve LC symptoms with no expected long-term harm.

Direct effects of prolonged TNF-α and IL-6 exposure on neural activity in human iPSC-derived neuron-astrocyte co-cultures

Cognitive impairment is one of the many symptoms reported by individuals suffering from long-COVID and other post-viral infection disorders such as myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). A common factor among these conditions is a sustained immune response and increased levels of inflammatory cytokines. Tumor necrosis factor alpha (TNF-α) and interleukin-6 (IL-6) are two such cytokines that are elevated in patients diagnosed with long-COVID and ME/CFS. In this study, we characterized the changes in neural functionality, secreted cytokine profiles, and gene expression in co-cultures of human iPSC-derived neurons and primary astrocytes in response to prolonged exposure to TNF-α and IL-6. We found that exposure to TNF-α produced both a concentration-independent and concentration-dependent response in neural activity. Burst duration was significantly reduced within a few days of exposure regardless of concentration (1 pg/mL - 100 ng/mL) but returned to baseline after 7 days. Treatment with low concentrations of TNF-α (e.g., 1 and 25 pg/mL) did not lead to changes in the secreted cytokine profile or gene expression but still resulted in significant changes to electrophysiological features such as interspike interval and burst duration. Conversely, treatment with high concentrations of TNF-α (e.g., 10 and 100 ng/mL) led to reduced spiking activity, which may be correlated to changes in neural health, gene expression, and increases in inflammatory cytokine secretion (e.g., IL-1β, IL-4, and CXCL-10) that were observed at higher TNF-α concentrations. Prolonged exposure to IL-6 led to changes in bursting features, with significant reduction in the number of spikes in bursts across a wide range of treatment concentrations (i.e., 1 pg/mL-10 ng/mL). In combination, the addition of IL-6 appears to counteract the changes to neural function induced by low concentrations of TNF-α, while at high concentrations of TNF-α the addition of IL-6 had little to no effect. Conversely, the changes to electrophysiological features induced by IL-6 were lost when the cultures were co-stimulated with TNF-α regardless of the concentration, suggesting that TNF-α may play a more pronounced role in altering neural function. These results indicate that increased concentrations of key inflammatory cytokines associated with long-COVID can directly impact neural function and may be a component of the cognitive impairment associated with long-COVID and other post-viral infection disorders.

A Narrative Review of the Efficacy of Long COVID Interventions on Brain Fog, Processing Speed, and Other Related Cognitive Outcomes

In the years following the global emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), or COVID-19, researchers have become acutely aware of long-term symptomology associated with this disease, often termed long COVID. Long COVID is associated with pervasive symptoms affecting multiple organ systems. Neurocognitive symptoms are reported by up to 40% of long COVID patients, with resultant effects of loss of daily functioning, employment issues, and enormous economic impact and high healthcare utilization. The literature on effective, safe, and non-invasive interventions for the remediation of the cognitive consequences of long COVID is scarce and poorly described. Of specific interest to this narrative review is the identification of potential interventions for long COVID-associated neurocognitive deficits. Articles were sourced from PubMed, EBSCO, Scopus, and Embase following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. Articles published between the dates of January 2020 and 30 June 2024 were included in the search. Twelve studies were included in the narrative review, including a feasibility study, a pilot study, a case series, a case study, and an observational study, in addition to three randomized clinical trials and four interventional studies. Overall, treatment interventions such as cognitive training, non-invasive brain stimulation therapy, exercise rehabilitation, targeted pharmacological intervention, and other related treatment paradigms show promise in reducing long COVID cognitive issues. This narrative review highlights the need for more rigorous experimental designs and future studies are needed to fully evaluate treatment interventions for persistent cognitive deficits associated with 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.

Neuroinflammation in Post COVID-19 Sequelae: Neuroinvasion and Neuroimmune Crosstalk

The emergence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in December 2019 triggered a swift global spread, leading to a devastating pandemic. Alarmingly, approximately one in four individuals diagnosed with coronavirus disease 2019 (COVID-19) experience varying degrees of cognitive impairment, raising concerns about a potential increase in neurological sequelae cases. Neuroinflammation seems to be the key pathophysiological hallmark linking mild respiratory COVID-19 to cognitive impairment, fatigue, and neurological sequelae in COVID-19 patients, highlighting the interaction between the nervous and immune systems following SARS-CoV-2 infection. Several hypotheses have been proposed to explain how the virus disrupts physiological pathways to trigger inflammation within the CNS, potentially leading to neuronal damage. These include neuroinvasion, systemic inflammation, disruption of the lung and gut-brain axes, and reactivation of latent viruses. This review explores the potential origins of neuroinflammation and the underlying neuroimmune cross-talk, highlighting important unanswered questions in the field. Addressing these fundamental issues could enhance our understanding of the virus's impact on the CNS and inform strategies to mitigate its detrimental effects.

LED-emitted blue light improves quality of life and reduces fatigue after COVID-19 infection

Introduction

Despite multiple clinical presentations of long COVID, the most common symptom encountered by the patients is fatigue which significantly impacts daily functioning and quality of life. There are, however, multiple unanswered questions regarding the treatment of fatigue among long COVID patients. Several studies highlighted that repetitive exposure to blue light may alleviate the fatigue in different groups of patients but the studies on the efficacy of blue light therapy in treatment of fatigue in long COVID patients are lacking.

Aim

To evaluate the effects of blue light therapy in treatment of fatigue among COVID-19 survivors.

Material and methods

The study comprised of 43 adults who underwent COVID-19 infection with a subjective feeling of fatigue 4 weeks after the infection. All participants underwent 10 full-body blue light irradiation for 15 min a day for 5 consecutive days each week. All participants were assessed using the Fatigue Severity Scale (FSS), Short Form 36 Vitality Subscale (SF-36) and Dermatology Life Quality Index (DLQI). Serum samples were taken to measure the levels of tryptophan, kynurenine, kynurenic acid, quinolinic acid and serotonin before and after irradiation.

Results

Irradiation with blue light resulted in a significant decrease in FSS and DLQI as well as in an increase in SF-36 and serum levels of tryptophan, kynurenine and serotonin.

Conclusions

Our study shows that blue light therapy could be used as adjunctive treatment of fatigue and provide an opportunity for further scientific inquiries.

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.

Cardiovascular dysautonomia in postacute sequelae of SARS-CoV-2 infection

Coronavirus disease 2019 (COVID-19) has led to a worldwide pandemic that continues to transform but will not go away. Cardiovascular dysautonomia in postacute sequelae of severe acute respiratory syndrome coronavirus 2 infection has led to persistent symptoms in a large number of patients. Here, we define the condition and its associated symptoms as well as potential mechanisms responsible. We provide a careful and complete overview of the topic addressing novel studies and a generalized approach to the management of individuals with this complex and potentially debilitating problem. We also discuss future research directions and the important knowledge gaps to be addressed in ongoing and planned studies.

Potential Beneficial Effects of Naringin and Naringenin on Long COVID-A Review of the Literature

Coronavirus disease 2019 (COVID-19) caused a severe epidemic due to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Recent studies have found that patients do not completely recover from acute infections, but instead, suffer from a variety of post-acute sequelae of SARS-CoV-2 infection, known as long COVID. The effects of long COVID can be far-reaching, with a duration of up to six months and a range of symptoms such as cognitive dysfunction, immune dysregulation, microbiota dysbiosis, myalgic encephalomyelitis/chronic fatigue syndrome, myocarditis, pulmonary fibrosis, cough, diabetes, pain, reproductive dysfunction, and thrombus formation. However, recent studies have shown that naringenin and naringin have palliative effects on various COVID-19 sequelae. Flavonoids such as naringin and naringenin, commonly found in fruits and vegetables, have various positive effects, including reducing inflammation, preventing viral infections, and providing antioxidants. This article discusses the molecular mechanisms and clinical effects of naringin and naringenin on treating the above diseases. It proposes them as potential drugs for the treatment of long COVID, and it can be inferred that naringin and naringenin exhibit potential as extended long COVID medications, in the future likely serving as nutraceuticals or clinical supplements for the comprehensive alleviation of the various manifestations of COVID-19 complications.