Long-term neurological dysfunction associated with COVID-19: Lessons from influenza and inflammatory diseases?

Abstract:

As the COVID-19 pandemic persists, SARS-CoV-2 infection is increasingly associated with long-term neurological side effects including cognitive impairment, fatigue, depression, and anxiety, colloquially known as “long-COVID.” While the full extent of long-COVID neuropathology across years or even decades is not yet known, we can perhaps take direction from long-standing research into other respiratory diseases, such as influenza, that can present with similar long-term neurological consequences.

In this review, we highlight commonalities in the neurological impacts of influenza and COVID-19. We first focus on the common potential mechanisms underlying neurological sequelae of long-COVID and influenza, namely (1) viral neurotropism and (2) dysregulated peripheral inflammation. The latter, namely heightened peripheral inflammation leading to central nervous system dysfunction, is emerging as a shared mechanism in various peripheral inflammatory or inflammation-associated diseases and conditions.

We then discuss historical and modern examples of influenza- and COVID-19-associated cognitive impairment, depression, anxiety, and fatigue, revealing key similarities in their neurological sequelae. Although we are learning that the effects of influenza and COVID differ somewhat in terms of their influence on the brain, as the impacts of long-COVID grow, such comparisons will likely prove valuable in guiding ongoing research into long-COVID, and perhaps foreshadow what could be in store for individuals with COVID-19 and their brain health.

Source: Volk P, Rahmani Manesh M, Warren ME, Besko K, Gonçalves de Andrade E, Wicki-Stordeur LE, Swayne LA. Long-term neurological dysfunction associated with COVID-19: Lessons from influenza and inflammatory diseases? J Neurochem. 2023 Nov 28. doi: 10.1111/jnc.16016. Epub ahead of print. PMID: 38014645. https://onlinelibrary.wiley.com/doi/10.1111/jnc.16016 (Full text)

Exploring the Influence of VDR Genetic Variants TaqI, ApaI, and FokI on COVID-19 Severity and Long-COVID-19 Symptoms

Abstract:

There is increasing evidence regarding the importance of vitamin D in the prognosis of coronavirus disease 2019 (COVID-19). Genetic variants in the vitamin D receptor (VDR) gene affect the response to vitamin D and have been linked to various diseases. This study investigated the associations of the major VDR genetic variants ApaIFokI, and TaqI with the severity and long post-infection symptoms of COVID-19. In total, 100 Jordanian patients with confirmed COVID-19 were genotyped for the VDR ApaIFokI, and TaqI variants using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.
COVID-19 severity, the most commonly reported long-COVID-19 symptoms that lasted for >4 weeks from the onset of infection, and other variables were analyzed according to VDR genetic variants. In this study, ApaI and FokI polymorphisms showed no significant associations with COVID-19 severity (p > 0.05). However, a significant association was detected between the TaqI polymorphism and the severity of symptoms after infection with the SARS-CoV-2 virus (p = 0.04). The wild-type TaqI genotype was typically present in patients with mild illness, whereas the heterozygous TaqI genotype was present in asymptomatic patients.
With regard to long-COVID-19 symptoms, the VDR heterozygous ApaI and wild-type TaqI genotypes were significantly associated with persistent fatigue and muscle pain after COVID-19 (p ˂ 0.05). Most carriers of the heterozygous ApaI genotype and carriers of the wild-type TaqI genotype reported experiencing fatigue and muscle pain that lasted for more than 1 month after the onset of COVID-19. Furthermore, the TaqI genotype was associated with persistent shortness of breath after COVID-19 (p = 0.003). Shortness of breath was more common among individuals with homozygous TaqI genotype than among individuals with the wild-type or heterozygous TaqI genotype.
VDR TaqI is a possible genetic variant related to both COVID-19 severity and long-COVID-19 symptoms among Jordanian individuals. The associations between VDR TaqI polymorphisms and long-COVID-19 symptoms should be investigated in larger and more diverse ethnic populations.
Source: Alhammadin G, Jarrar Y, Madani A, Lee S-J. Exploring the Influence of VDR Genetic Variants TaqIApaI, and FokI on COVID-19 Severity and Long-COVID-19 Symptoms. Journal of Personalized Medicine. 2023; 13(12):1663. https://doi.org/10.3390/jpm13121663 https://www.mdpi.com/2075-4426/13/12/1663 (Full text)

SGLT2 Inhibitors in Long COVID Syndrome: Is There a Potential Role?

Abstract:

The coronavirus disease (COVID)-19 has turned into a pandemic causing a global public health crisis. While acute COVID-19 mainly affects the respiratory system and can cause acute respiratory distress syndrome, an association with persistent inflammatory stress affecting different organ systems has been elucidated in long COVID syndrome (LCS).
Increased severity and mortality rates have been reported due to cardiophysiological and metabolic systemic disorders as well as multiorgan failure in COVID-19, additionally accompanied by chronic dyspnea and fatigue in LCS. Hence, novel therapies have been tested to improve the outcomes of LCS of which one potential candidate might be sodium–glucose cotransporter 2 (SGLT2) inhibitors.
The aim of this narrative review was to discuss rationales for investigating SGLT2 inhibitor therapy in people suffering from LCS. In this regard, we discuss their potential positive effects—next to the well described “cardio-renal-metabolic” conditions—with a focus on potential anti-inflammatory and beneficial systemic effects in LCS. However, potential beneficial as well as potential disadvantageous effects of SGLT2 inhibitors on the prevalence and long-term outcomes of COVID-19 will need to be established in ongoing research.
Source: Zimmermann P, Sourij H, Aberer F, Rilstone S, Schierbauer J, Moser O. SGLT2 Inhibitors in Long COVID Syndrome: Is There a Potential Role? Journal of Cardiovascular Development and Disease. 2023; 10(12):478. https://doi.org/10.3390/jcdd10120478 https://www.mdpi.com/2308-3425/10/12/478 (Full text)

Drawing the Line Between Postacute Sequelae of COVID-19 and Functional Neurologic Disorders A Daunting Clinical Overlap or Irrelevant Conundrum?

Abstract:

Coronavirus disease 2019 (COVID-19) is an acute infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in its multiple variants that classically presents with cough, fatigue, fever, headache, myalgias, and diarrhea. As vaccination becomes widely available and infection rates facilitate herd immunity across the globe, more attention has been given to long-term symptoms that may persist after the index infection, which include impairments in concentration, executive dysfunction, sensory disturbances, depression, anxiety, fatigue, and cough, among other symptoms classified under the umbrella term of postacute sequelae of SARS-CoV-2 infection (PASC).

Functional neurologic disorder (FND), also known as conversion disorder and functional neurologic symptom disorder, refers to the presence of one or more symptoms of altered voluntary motor or sensory function that are incompatible with and not better explained by a known neurological or medical condition that causes significant distress and functional impairment. Although the diagnosis of FND may not require the identification of an underlying psychological stressor, being diagnosed with an FND can worsen stigma and shift attention and resources away from other medical concerns that should be concomitantly addressed.

This review summarizes the literature on the overlapping nature and discrimination of PASC from FND in COVID-19 survivors. Based on this, we develop a treatment framework that targets unique domains of these complex overlapping presentations, following a multidisciplinary approach with an individualized treatment plan inclusive of physical and psychological interventions focused on functional rehabilitation.

Source: Sales, Paulo M.G. MD, MS; Greenfield, Melissa J. PsyD; Pinkhasov, Aaron MD; Viswanathan, Ramaswamy MD, DrMedSc; Saunders, Ramotse MD§; Huremović, Damir MD, MPP. Drawing the Line Between Postacute Sequelae of COVID-19 and Functional Neurologic Disorders: A Daunting Clinical Overlap or Irrelevant Conundrum?. The Journal of Nervous and Mental Disease 211(12):p 882-889, December 2023. | DOI: 10.1097/NMD.0000000000001643 https://journals.lww.com/jonmd/abstract/2023/12000/drawing_the_line_between_postacute_sequelae_of.2.aspx

Long Covid Clinical Severity Types Based on Symptoms and Functional Disability: A Longitudinal Evaluation

Abstract:

Background: Long Covid (LC) is a multisystem clinical syndrome with Functional Disability (FD) and compromised Overall Health (OH). There is a lack of distinct clinical symptom clusters (phenotypes) identified in LC so far but there is emerging information on LC clinical severity types. This study explores the consistency of these clinical severity types over time and the relationship between Symptom Severity (SS), FD, and OH in the context of the clinical severity types in a prospective sample.

Methods: A purposive sample of LC patients recruited to the LOng COvid Multidisciplinary consortium Optimising Treatments and servIces acrOss the NHS (LOCOMOTION) study were assessed using the modified COVID-19 Yorkshire Rehabilitation Scale (C19-YRSm) at two assessment time points. A cluster analysis for clinical severity types was undertaken at both time points using k-means partition using two, three, and four initial clusters and different starting values. Cluster analysis was also carried out to assess the presence of symptom phenotypes (symptom clusters).

Findings: Cross-sectional data was available for 759 patients with 356 patients completing C19-YRSm at the two assessment points. Mean age was 46·8 years (SD = 12·7), 69·4% were females, and median duration of LC symptoms at first assessment was 360 days (IQR 217 to 703 days). Cluster analysis revealed three distinct SS and FD clinical severity types – mild (N=96), moderate (N=422), and severe (N=241) – with no distinct symptom phenotypes. The three-level clinical severity pattern remained consistent over time between the two assessments, with 51% of patients switching the clinical severity type between the assessments. The fluctuation was independent of the LC severity and time between the assessments.

Interpretation: This is the first study in the literature to show the consistency of the three clinical severity types over time with patients also switching between severity types indicating the fluctuating nature of LC.

Source: Sivan, Manoj and Smith, Adam B. and Osborne, Thomas and Goodwin, Madeline and Lawrence, Román Rocha and Baley, Sareeta and Williams, Paul and Lee, Cassie and Davies, Helen and Balasundaram, Kumaran and Greenwood, Darren C., Long Covid Clinical Severity Types Based on Symptoms and Functional Disability: A Longitudinal Evaluation. Available at SSRN: https://ssrn.com/abstract=4642650 or http://dx.doi.org/10.2139/ssrn.4642650 https://papers.ssrn.com/sol3/papers.cfm?abstract_id=4642650 (Full text available as PDF file)

The association of insomnia with long COVID: An international collaborative study (ICOSS-II)

Abstract:

Objective: There is evidence of a strong association between insomnia and COVID-19, yet few studies have examined the relationship between insomnia and long COVID. This study aimed to investigate whether COVID-19 patients with pre-pandemic insomnia have a greater risk of developing long COVID and whether long COVID is in turn associated with higher incident rates of insomnia symptoms after infection.

Methods: Data were collected cross-sectionally (May-Dec 2021) as part of an international collaborative study involving participants from 16 countries. A total of 2311 participants (18-99 years old) with COVID-19 provided valid responses to a web-based survey about sleep, insomnia, and health-related variables. Log-binomial regression was used to assess bidirectional associations between insomnia and long COVID. Analyses were adjusted for age, sex, and health conditions, including sleep apnea, attention and memory problems, chronic fatigue, depression, and anxiety.

Results: COVID-19 patients with pre-pandemic insomnia showed a higher risk of developing long COVID than those without pre-pandemic insomnia (70.8% vs 51.4%; adjusted relative risk [RR]: 1.33, 95% confidence interval [CI]: 1.07-1.65). Among COVID-19 cases without pre-pandemic insomnia, the rates of incident insomnia symptoms after infection were 24.1% for short COVID cases and 60.6% for long COVID cases (p < .001). Compared with short COVID cases, long COVID cases were associated with an increased risk of developing insomnia symptoms (adjusted RR: 2.00; 95% CI: 1.50-2.66).

Conclusions: The findings support a bidirectional relationship between insomnia and long COVID. These findings highlight the importance of addressing sleep and insomnia in the prevention and management of long COVID.

Source: Chen SJ, Morin CM, Ivers H, Wing YK, Partinen M, Merikanto I, Holzinger B, Espie CA, De Gennaro L, Dauvilliers Y, Chung F, Yordanova J, Vidović D, Reis C, Plazzi G, Penzel T, Nadorff MR, Matsui K, Mota-Rolim S, Leger D, Landtblom AM, Korman M, Inoue Y, Hrubos-Strøm H, Chan NY, Bjelajac AK, Benedict C, Bjorvatn B. The association of insomnia with long COVID: An international collaborative study (ICOSS-II). Sleep Med. 2023 Dec;112:216-222. doi: 10.1016/j.sleep.2023.09.034. Epub 2023 Oct 24. PMID: 37922783. https://www.sciencedirect.com/science/article/abs/pii/S1389945723003672

Complement dysregulation is a predictive and therapeutically amenable feature of long COVID

Abstract:

Background Long COVID encompasses a heterogeneous set of ongoing symptoms that affect many individuals after recovery from infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The underlying biological mechanisms nonetheless remain obscure, precluding accurate diagnosis and effective intervention. Complement dysregulation is a hallmark of acute COVID-19 but has not been investigated as a potential determinant of long COVID.

Methods We quantified a series of complement proteins, including markers of activation and regulation, in plasma samples from healthy convalescent individuals with a confirmed history of infection with SARS-CoV-2 and age/ethnicity/gender/infection/vaccine-matched patients with long COVID.

Findings Markers of classical (C1s-C1INH complex), alternative (Ba, iC3b), and terminal pathway (C5a, TCC) activation were significantly elevated in patients with long COVID. These markers in combination had a receiver operating characteristic predictive power of 0.794. Other complement proteins and regulators were also quantitatively different between healthy convalescent individuals and patients with long COVID. Generalized linear modeling further revealed that a clinically tractable combination of just four of these markers, namely the activation fragments iC3b, TCC, Ba, and C5a, had a predictive power of 0.785.

Conclusions These findings suggest that complement biomarkers could facilitate the diagnosis of long COVID and further suggest that currently available inhibitors of complement activation could be used to treat long COVID.

Source: Kirsten Baillie, Helen E Davies, Samuel B K Keat, Kristin Ladell, Kelly L Miners, Samantha A Jones, Ermioni Mellou, Erik J M Toonen, David A Price, B Paul Morgan, Wioleta M Zelek. Complement dysregulation is a predictive and therapeutically amenable feature of long COVID.
medRxiv 2023.10.26.23297597; doi: https://doi.org/10.1101/2023.10.26.23297597 https://www.medrxiv.org/content/10.1101/2023.10.26.23297597v1.full-text (Full text)

Post-COVID exercise intolerance is associated with capillary alterations and immune dysregulations in skeletal muscles

Abstract:

The SARS-CoV-2 pandemic not only resulted in millions of acute infections worldwide, but also in many cases of post-infectious syndromes, colloquially referred to as “long COVID”. Due to the heterogeneous nature of symptoms and scarcity of available tissue samples, little is known about the underlying mechanisms.

We present an in-depth analysis of skeletal muscle biopsies obtained from eleven patients suffering from enduring fatigue and post-exertional malaise after an infection with SARS-CoV-2. Compared to two independent historical control cohorts, patients with post-COVID exertion intolerance had fewer capillaries, thicker capillary basement membranes and increased numbers of CD169+ macrophages. SARS-CoV-2 RNA could not be detected in the muscle tissues.

In addition, complement system related proteins were more abundant in the serum of patients with PCS, matching observations on the transcriptomic level in the muscle tissue. We hypothesize that the initial viral infection may have caused immune-mediated structural changes of the microvasculature, potentially explaining the exercise-dependent fatigue and muscle pain.

Source: Aschman, T., Wyler, E., Baum, O. et al. Post-COVID exercise intolerance is associated with capillary alterations and immune dysregulations in skeletal muscles. acta neuropathol commun 11, 193 (2023). https://doi.org/10.1186/s40478-023-01662-2 https://actaneurocomms.biomedcentral.com/articles/10.1186/s40478-023-01662-2 (Full text)

Exploring the Joint Potential of Inflammation, Immunity, and Receptor-Based Biomarkers for Evaluating ME/CFS Progression

Abstract:

Background: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating chronic condition with no identified diagnostic biomarkers to date. Its prevalence is as high as 0.89% according to metastudies, with a quarter of patients bed-or home-bound, which presents a serious public health challenge. Investigations into the inflammation-immunity axis is encouraged by links to outbreaks and disease waves. Recently, research of our group revealed that antibodies to beta2adrenergic (anti-β2AdR) and muscarinic acetylcholine (anti-M4) receptors demonstrate sensitivity to the progression of ME/CFS.

The purpose of this study is to investigate the joint potential of inflammatome -characterized by interferon (IFN)-γ, tumor necrosis factor (TNF)-α, interleukin (IL)-2, IL-21, Il-23, IL-6, IL-17A, Activin-B, immunome (IgG1, IgG2, IgG3, IgG4, IgM, IgA) and receptor-based biomarkers (anti-M3, anti-M4, anti-β2AdR) determined for evaluating ME/CFS progression, and to identify an optimal selection for future validation in prospective clinical studies.

Methods: A dataset was used originating from 188 persons, including 54 healthy controls, 30 patients classified as “mild” by severity, 73 as “moderate,” and 31 as “severe,” clinically assessed by Fukuda/CDC 1994 and International consensus criteria. Markers characterizing inflammatome, immunome, and receptor-based biomarkers were determined in blood plasma via ELISA and multiplex methods.

Statistical analysis was done via correlation analysis, principal component, and linear discriminant analysis, and random forest classification; inter-group differences tested via nonparametric Kruskal-Wallis H test followed by the two-stage linear step-up procedure of Benjamini, Krieger, and Yekutieli, and via Mann-Whitney U test.

The association between inflammatome and immunome markers is broader and stronger (coupling) in severe group. Principal component factoring separate components affiliated with inflammatome, immunome, and receptor biomarkers. Random forest modeling demonstrates an out-of-box accuracy for splitting healthy/with condition groups of over 90%, and of 45% for healthy/severity groups. Classifiers with the highest potential are anti-β2AdR, anti-M4, IgG4, IL-2, and IL-6.

Discussion: Association between inflammatome and immunome markers is a candidate for controlled clinical study of ME/CFS progression markers that could be used for treatment individualization. Thus, coupling effects between inflammation and immunity have a potential for the identification of prognostic factors in the context of ME/CFS progression mechanism studies.

Source: Uldis Berkis, Simons Svirskis, Angelika Krumina, Sabine Gravelsina, Anda Vilmane, Diana Araja, Zaiga Nora-Krukle, Modra Murovska. Exploring the Joint Potential of Inflammation, Immunity, and Receptor-Based Biomarkers for Evaluating ME/CFS Progression. Frontiers in Immunology. Sec. Autoimmune and Autoinflammatory Disorders : Autoimmune Disorders. Volume 14- 2023.  https://www.frontiersin.org/articles/10.3389/fimmu.2023.1294758/abstract

An international survey of experiences and attitudes towards transcutaneous auricular vagus nerve stimulation for people with Myalgic Encephalomyelitis/chronic fatigue syndrome

Abstract:

Background and objectives: Myalgic encephalomyelitis (ME) is a complex, multi-system neurological condition. Dysfunction of the autonomic nervous system is a primary feature in diagnostic criteria, and management may include attempts to stimulate the parasympathetic nervous system. Transcutaneous auricular vagus nerve stimulation is an intervention that has been researched in neurological disorders, e.g. epilepsy, depression. While little evidence exists for its use in ME, this survey aims to explore the experiences and attitudes of people with ME to this intervention.

Methods: A 31-question online survey was devised and released on ME websites, Twitter and Facebook pages. People with ME read the information sheet and followed an online link to the survey. The survey was open for four weeks and all answers were anonymous.

Results: 116 responses were received. 56% of respondents reported favourable effects. Benefits of transcutaneous auricular vagus nerve stimulation were identified in relation to post exertional malaise, pain, gut problems, urinary problems, mental health, and the ability to leave the house. 67.2% of respondents would recommend the intervention to other people with ME. However, 4.3% would not recommend it and 6% reported it made them worse. 8.6% received support in setting up the device from healthcare workers.

Conclusion: The survey highlights that many people with ME experience significant benefits from using transcutaneous auricular vagus nerve stimulation; however due to potential negative effects there is the need for formal intervention studies to clearly identify safe parameters.

Source: Karen Leslie, Nicola Clague-Baker, Mohammad Abdelfattah Atallah Madi, Dawn Wiley, Andrea Parker, Michelle Bull & Natalie Hilliard. (2023) An international survey of experiences and attitudes towards transcutaneous auricular vagus nerve stimulation for people with Myalgic Encephalomyelitis/chronic fatigue syndrome, Fatigue: Biomedicine, Health & Behavior, DOI: 10.1080/21641846.2023.2286029 https://www.tandfonline.com/doi/abs/10.1080/21641846.2023.2286029