Hippocampal subfield volume alterations and associations with severity measures in long COVID and ME/CFS: A 7T MRI study

Abstract:

Long COVID and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) patients share similar symptoms including post-exertional malaise, neurocognitive impairment, and memory loss. The neurocognitive impairment in both conditions might be linked to alterations in the hippocampal subfields. Therefore, this study compared alterations in hippocampal subfields of 17 long COVID, 29 ME/CFS patients, and 15 healthy controls (HC).

Structural MRI data was acquired with sub-millimeter isotropic resolution on a 7 Telsa MRI scanner and hippocampal subfield volumes were then estimated for each participant using FreeSurfer software. Our study found significantly larger volumes in the left hippocampal subfields of both long COVID and ME/CFS patients compared to HC.

These included the left subiculum head (long COVID; p = 0.01, ME/CFS; p = 0.002,), presubiculum head (long COVID; p = 0.004, ME/CFS; p = 0.005), molecular layer hippocampus head (long COVID; p = 0.014, ME/CFS; p = 0.011), and whole hippocampal head (long COVID; p = 0.01, ME/CFS; p = 0.01). Notably, hippocampal subfield volumes were similar between long COVID and ME/CFS patients.

Additionally, we found significant associations between hippocampal subfield volumes and severity measures of ‘Pain’, ‘Duration of illness’, ‘Severity of fatigue’, ‘Impaired concentration’, ‘Unrefreshing sleep’, and ‘Physical function’ in both conditions. These findings suggest that hippocampal alterations may contribute to the neurocognitive impairment experienced by long COVID and ME/CFS patients. Furthermore, our study highlights similarities between these two conditions.

Source: Thapaliya K, Marshall-Gradisnik S, Eaton-Fitch N, Barth M, Inderyas M, Barnden L. Hippocampal subfield volume alterations and associations with severity measures in long COVID and ME/CFS: A 7T MRI study. PLoS One. 2025 Jan 13;20(1):e0316625. doi: 10.1371/journal.pone.0316625. PMID: 39804864; PMCID: PMC11729965. https://pmc.ncbi.nlm.nih.gov/articles/PMC11729965/ (Full text)

More than “Brain Fog”: Cognitive Dysfunction and the Role of Occupational Therapy in Long COVID

Abstract:

Long COVID is a disabling condition which affects occupational performance and quality of life. It interferes with activities of daily living, work, and many meaningful life roles. Cognitive dysfunction is a frequently reported symptom, yet it is commonly overlooked. It is important that cognitive activity is considered when working with people with long COVID, particularly when identifying triggers of post exertional symptom exacerbation. There are many potential mechanisms that could be driving cognitive dysfunction in long COVID including neuroinflammation, viral persistence, vascular damage, and orthostatic intolerance. It is important to consider these to help guide intervention.

The purpose of this clinical perspective is to highlight the debilitating impact of cognitive dysfunction in those with long COVID and share the key role of occupational therapists in this area. Cognitive dysfunction may be missed on standardized assessments as they may not be sensitive enough due to the episodic nature of symptoms. Occupational therapists can play a key role in this area as they are experts in assessing occupational performance and in providing safe cognitive assessment and rehabilitation.

Source: Skiffington, Helen OT, BSc Hons1,2; Breen, Ciara MSc, HCM3,4,5. More than “Brain Fog”: Cognitive Dysfunction and the Role of Occupational Therapy in Long COVID. Cardiopulmonary Physical Therapy Journal 36(1):p 39-49, January 2025. | DOI: 10.1097/CPT.0000000000000274 https://journals.lww.com/cptj/fulltext/2025/01000/more_than__brain_fog___cognitive_dysfunction_and.7.aspx (Full text)

Phase-dependent trends in the prevalence of myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS) related to long COVID: A criteria-based retrospective study in Japan

Abstract:

Background: The characteristics of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) related to COVID-19 have remained uncertain. To elucidate the clinical trend of ME/CFS induced by long COVID, we examined data for patients who visited our outpatient clinic established in a university hospital during the period from Feb 2021 to July 2023.

Methods: Long COVID patients were classified into two groups, an ME/CFS group and a non-ME/CFS group, based on three diagnostic criteria.

Results: The prevalence of ME/CFS in the long COVID patients was 8.4% (62 of 739 cases; female: 51.6%) and factors related to ME/CFS were severe illness, smoking and alcohol drinking habits, and fewer vaccinations. The frequency of ME/CFS decreased from 23.9% in the Preceding period to 13.7% in the Delta-dominant period and to 3.3% in the Omicron-dominant period. Fatigue and headache were commonly frequent complaints in the ME/CFS group, and the frequency of poor concentration in the ME/CFS group was higher in the Omicron period. Serum ferritin levels were significantly higher in female patients in the ME/CFS group infected in the Preceding period. In the ME/CFS group, the proportion of patients complaining of brain fog significantly increased from 22.2% in the Preceding period to 47.9% in the Delta period and to 81.3% in the Omicron period. The percentage of patients who had received vaccination was lower in the ME/CFS group than the non-ME/CFS group over the study period, whereas there were no differences in the vaccination rate between the groups in each period.

Conclusion: The proportion of long COVID patients who developed ME/CFS strictly diagnosed by three criteria was lower among patients infected in the Omicron phase than among patients infected in the other phases, while the proportion of patients with brain fog inversely increased. Attention should be paid to the variant-dependent trends of ME/CFS triggered by long COVID (300 words).

Source: Morita S, Tokumasu K, Otsuka Y, Honda H, Nakano Y, Sunada N, Sakurada Y, Matsuda Y, Soejima Y, Ueda K, Otsuka F. Phase-dependent trends in the prevalence of myalgic encephalomyelitis / chronic fatigue syndrome (ME/CFS) related to long COVID: A criteria-based retrospective study in Japan. PLoS One. 2024 Dec 9;19(12):e0315385. doi: 10.1371/journal.pone.0315385. PMID: 39652555; PMCID: PMC11627433. https://pmc.ncbi.nlm.nih.gov/articles/PMC11627433/ (Full text)

Plasma taurine level is linked to symptom burden and clinical outcomes in post-COVID condition

Abstract:

Background: A subset of individuals (10-20%) experience post-COVID condition (PCC) subsequent to initial SARS-CoV-2 infection, which lacks effective treatment. PCC carries a substantial global burden associated with negative economic and health impacts. This study aims to evaluate the association between plasma taurine levels with self-reported symptoms and adverse clinical outcomes in patients with PCC.

Methods and findings: We analyzed the plasma proteome and metabolome of 117 individuals during their acute COVID-19 hospitalization and at the convalescence phase six-month post infection. Findings were compared with 28 age and sex-matched healthy controls. Plasma taurine levels were negatively associated with PCC symptoms and correlated with markers of inflammation, tryptophan metabolism, and gut dysbiosis. Stratifying patients based on the trajectories of plasma taurine levels during six-month follow-up revealed a significant association with adverse clinical events. Increase in taurine levels during the transition to convalescence were associated with a reduction in adverse events independent of comorbidities and acute COVID-19 severity. In a multivariate analysis, increased plasma taurine level between acute and convalescence phase was associated with marked protection from adverse clinical events with a hazard ratio of 0.13 (95% CI: 0.05-0.35; p<0.001).

Conclusions: Taurine emerges as a promising predictive biomarker and potential therapeutic target in PCC. Taurine supplementation has already demonstrated clinical benefits in various diseases and warrants exploration in large-scale clinical trials for alleviating PCC.

Source: Khoramjoo M, Wang K, Srinivasan K, Gheblawi M, Mandal R, Rousseau S, Wishart D, Prasad V, Richer L, Cheung AM, Oudit GY. Plasma taurine level is linked to symptom burden and clinical outcomes in post-COVID condition. PLoS One. 2024 Jun 5;19(6):e0304522. doi: 10.1371/journal.pone.0304522. PMID: 38837993; PMCID: PMC11152273. https://pmc.ncbi.nlm.nih.gov/articles/PMC11152273/ (Full text)

Overlapping conditions in Long COVID at a multisite academic center

Abstract:

Background: Many patients experience persistent symptoms after COVID-19, a syndrome referred to as Long COVID (LC). The goal of this study was to identify novel new or worsening comorbidities self-reported in patients with LC.

Methods: Patients diagnosed with LC (n = 732) at the Mayo Long COVID Care Clinic in Rochester, Minnesota and Jacksonville, Florida were sent questionnaires to assess the development of new or worsening comorbidities following COVID-19 compared to patients with SARS-CoV-2 that did not develop LC (controls). Both groups were also asked questions screening for myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), generalized joint hypermobility (GJH) and orthostatic intolerance. 247 people with LC (33.7%) and 40 controls (50%) responded to the surveys.

Results: In this study LC patients averaged 53 years of age and were predominantly White (95%) women (75%). The greatest prevalence of new or worsening comorbidities following SARS-CoV-2 infection in patients with LC vs. controls reported in this study were pain (94.4% vs. 0%, p < 0.001), neurological (92.4% vs. 15.4%, p < 0.001), sleep (82.8% vs. 5.3%, p < 0.001), skin (69.8% vs. 0%, p < 0.001), and genitourinary (60.6% vs. 25.0%, p = 0.029) issues. 58% of LC patients screened positive for ME/CFS vs. 0% of controls (p < 0.001), 27% positive for GJH compared to 10% of controls (p = 0.026), and a positive average score of 4.0 on orthostatic intolerance vs. 0 (p < 0.001). The majority of LC patients with ME/CFS were women (77%).

Conclusion: We found that comorbidities across 12 surveyed categories were increased in patients following SARS-CoV-2 infection. Our data also support the overlap of LC with ME/CFS, GJH, and orthostatic intolerance. We discuss the pathophysiologic, research, and clinical implications of identifying these conditions with LC.

Source: Grach SL, Dudenkov DV, Pollack B, Fairweather D, Aakre CA, Munipalli B, Croghan IT, Mueller MR, Overgaard JD, Bruno KA, Collins NM, Li Z, Hurt RT, Tal MC, Ganesh R, Knight DTR. Overlapping conditions in Long COVID at a multisite academic center. Front Neurol. 2024 Oct 25;15:1482917. doi: 10.3389/fneur.2024.1482917. PMID: 39524912; PMCID: PMC11543549. https://pmc.ncbi.nlm.nih.gov/articles/PMC11543549/ (Full text)

Respiratory SARS-CoV-2 Infection Causes Skeletal Muscle Atrophy and Long-Lasting Energy Metabolism Suppression

Abstract:

Muscle fatigue represents the most prevalent symptom of long-term COVID, with elusive pathogenic mechanisms. We performed a longitudinal study to characterize histopathological and transcriptional changes in skeletal muscle in a hamster model of respiratory SARS-CoV-2 infection and compared them with influenza A virus (IAV) and mock infections.

Histopathological and bulk RNA sequencing analyses of leg muscles derived from infected animals at days 3, 30, and 60 post-infection showed no direct viral invasion but myofiber atrophy in the SARS-CoV-2 group, which was accompanied by persistent downregulation of the genes related to myofibers, ribosomal proteins, fatty acid β-oxidation, tricarboxylic acid cycle, and mitochondrial oxidative phosphorylation complexes.

While both SARS-CoV-2 and IAV infections induced acute and transient type I and II interferon responses in muscle, only the SARS-CoV-2 infection upregulated TNF-α/NF-κB but not IL-6 signaling in muscle. Treatment of C2C12 myotubes, a skeletal muscle cell line, with combined IFN-γ and TNF-α but not with IFN-γ or TNF-α alone markedly impaired mitochondrial function.

We conclude that a respiratory SARS-CoV-2 infection can cause myofiber atrophy and persistent energy metabolism suppression without direct viral invasion. The effects may be induced by the combined systemic interferon and TNF-α responses at the acute phase and may contribute to post-COVID-19 persistent muscle fatigue.

Source: Homma ST, Wang X, Frere JJ, Gower AC, Zhou J, Lim JK, tenOever BR, Zhou L. Respiratory SARS-CoV-2 Infection Causes Skeletal Muscle Atrophy and Long-Lasting Energy Metabolism Suppression. Biomedicines. 2024 Jun 28;12(7):1443. doi: 10.3390/biomedicines12071443. PMID: 39062017; PMCID: PMC11275164. https://pmc.ncbi.nlm.nih.gov/articles/PMC11275164/ (Full text)

Persistent Fatigue, Weakness, and Aberrant Muscle Mitochondria in Survivors of Critical COVID-19

Abstract:

Objectives: Persistent skeletal muscle dysfunction in survivors of critical illness due to acute respiratory failure is common, but biological data elucidating underlying mechanisms are limited. The objective of this study was to elucidate the prevalence of skeletal muscle weakness and fatigue in survivors of critical illness due to COVID-19 and determine if cellular changes associate with persistent skeletal muscle dysfunction.

Design: A prospective observational study in two phases: 1) survivors of critical COVID-19 participating in physical outcome measures while attending an ICU Recovery Clinic at short-term follow-up and 2) a nested cohort of patients performed comprehensive muscle and physical function assessments with a muscle biopsy; data were compared with non-COVID controls.

Setting: ICU Recovery Clinic and clinical laboratory.

Patients/subjects: Survivors of critical COVID-19 and non-COVID controls.

Interventions: None.

Measurements and main results: One hundred twenty patients with a median of 56 years old (interquartile range [IQR], 42-65 yr old), 43% female, and 33% individuals of underrepresented race attended follow-up 44 ± 17 days after discharge. Patients had a median Acute Physiology and Chronic Health Evaluation-II score of 24.0 (IQR, 16-29) and 98 patients (82%) required mechanical ventilation with a median duration of 14 days (IQR, 9-21 d). At short-term follow-up significant physical dysfunction was observed with 93% of patients reporting generalized fatigue and performing mean 218 ± 151 meters on 6-minute walk test (45% ± 30% of predicted). Eleven patients from this group agreed to participate in long-term assessment and muscle biopsy occurring a mean 267 ± 98 days after discharge. Muscle tissue from COVID exhibited a greater abundance of M2-like macrophages and satellite cells and lower activity of mitochondrial complex II and complex IV compared with controls.

Conclusions: Our findings suggest that aberrant repair and altered mitochondrial activity in skeletal muscle associates with long-term impairments in patients surviving an ICU admission for COVID-19.

Source: Mayer KP, Ismaeel A, Kalema AG, Montgomery-Yates AA, Soper MK, Kern PA, Starck JD, Slone SA, Morris PE, Dupont-Versteegden EE, Kosmac K. Persistent Fatigue, Weakness, and Aberrant Muscle Mitochondria in Survivors of Critical COVID-19. Crit Care Explor. 2024 Oct 16;6(10):e1164. doi: 10.1097/CCE.0000000000001164. PMID: 39412208; PMCID: PMC11487221. https://pmc.ncbi.nlm.nih.gov/articles/PMC11487221/ (Full text)

Inspiratory muscle training improves autonomic function in myalgic encephalomyelitis/chronic fatigue syndrome and post-acute sequelae of SARS-CoV-2: a pilot study

Abstract:

Post-acute sequelae of SARS-CoV-2 (PASC), or Long COVID, and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) are debilitating post-viral conditions with many symptomatic overlaps, including exercise intolerance and autonomic dysfunction. Both conditions are growing in prevalence, and effective safe treatment strategies must be investigated. We hypothesized that inspiratory muscle training (IMT) could be used in PASC and mild to moderate ME/CFS to mitigate symptoms, improve exercise capacity, and improve autonomic function.

We recruited healthy controls (n=12; 10 women), people with PASC (n=9; 8 women), and people with mild to moderate ME/CFS (n=12; 10 women) to complete 8 weeks of IMT. This project was registered as a clinical trial (NCT05196529) with clinicaltrials.gov.

After completion of IMT, all groups experienced improvements in inspiratory muscle pressure (p<0.001), 6-minute walk distance (p=0.002), resting heart rate (p=0.037), heart rate variability (p<0.05), and symptoms related to sleep (p=0.009). In the ME/CFS group only, after completion of IMT, there were additional improvements with regard to vascular function (p=0.001), secretomotor function (p=0.023), the total weighted score (p=0.005) of the COMPASS 31 autonomic questionnaire, and symptoms related to pain (p=0.016).

We found that after 8 weeks of IMT, people with PASC and/or ME/CFS could see some overall improvements in their autonomic function and symptomology.

Source: Edgell H, Pereira TJ, Kerr K, Bray R, Tabassum F, Sergio L, Badhwar S. Inspiratory muscle training improves autonomic function in myalgic encephalomyelitis/chronic fatigue syndrome and post-acute sequelae of SARS-CoV-2: a pilot study. Respir Physiol Neurobiol. 2024 Oct 5:104360. doi: 10.1016/j.resp.2024.104360. Epub ahead of print. PMID: 39374820. https://www.sciencedirect.com/science/article/pii/S1569904824001538 (Full text)

A pilot cross-sectional investigation of symptom clusters and associations with patient-reported outcomes in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Post COVID-19 Condition

Abstract:

Background: Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is associated with long-term disability and poor quality of life (QoL). Cardinal ME/CFS symptoms (including post-exertional malaise, cognitive dysfunction and sleep disturbances) have been observed in Post COVID-19 Condition (PCC). To gain further insight into the potential role of ME/CFS as a post-COVID-19 sequela, this study investigates associations between symptoms and patient-reported outcomes, as well as symptom clusters.
Methods: Participants included Australian residents aged between 18 and 65 years formally diagnosed with ME/CFS fulfilling the Canadian or International Consensus Criteria or PCC meeting the World Health Organization case definition. Validated, self-administered questionnaires collected participants’ sociodemographic and illness characteristics, symptoms, QoL and functional capacity. Associations between symptoms and patient-reported outcomes were investigated with multivariate linear regression models. Hierarchical cluster analysis was performed to identify symptom clusters.
Results: Most people with ME/CFS (pwME/CFS) and people with PCC (pwPCC) were female (n = 48/60, 80.0% and n = 19/30, 63.3%, respectively; p = 0.12). PwME/CFS were significantly younger (x̄=41.75, s = 12.91 years) than pwPCC (x̄=48.13, s =10.05 years; p =0.017). Autonomic symptoms (notably dyspnoea) were associated with poorer scores in most patient-reported outcome domains for both cohorts. None of the four symptom clusters identified were unique to ME/CFS or PCC. Clusters were largely delineated by the presence of gastrointestinal and neurosensory symptoms, illness duration, ME/CFS criteria met and total symptoms.
Conclusions: Illness duration may explain differences in symptom burden between pwME/CFS and pwPCC. PCC diagnostic criteria must be refined to distinguish pwPCC at risk of long-term ME/CFS-like illness and subsequently deliver necessary care and support.
Source: Weigel B, Eaton-Fitch N, Thapaliya K, Marshall-Gradisnik S. A pilot cross-sectional investigation of symptom clusters and associations with patient-reported outcomes in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Post COVID-19 Condition. Qual Life Res. 2024 Oct 3. doi: 10.1007/s11136-024-03794-x. Epub ahead of print. PMID: 39361124. https://link.springer.com/article/10.1007/s11136-024-03794-x (Full text)

 

The persistence of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) after SARS-CoV-2 infection: A systematic review and meta-analysis

Highlights:

  • SARS-CoV-2 can trigger Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.
  • 51% of Long COVID-19 patients have Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.
  • Long COVID-19 is a new name for an old disease.

Abstract:

Objectives: Long COVID-19 (LC) patients experience a number of chronic idiopathic symptoms that are highly similar to those of post-viral Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). We have therefore performed a systematic review and meta-analysis to determine the proportion of LC patients that satisfy ME/CFS diagnostic criteria.

Methods: Clinical studies published between January 2020 to May 2023 were identified using the PubMed, Web of Science, Embase and CINAHL databases. Publication inclusion/exclusion criteria were formulated using the global CoCoPop framework. Data were pooled using a random-effects model with a restricted maximum-likelihood estimator. Study quality was assessed using the Joanna Briggs Institute critical assessment tool.

Results: We identified 13 eligible studies that reported a total of 1,973 LC patients. Our meta-analysis indicated that 51% (95% CI, 42%-60%) of LC patients satisfied ME/CFS diagnostic criteria with fatigue, sleep disruption, and muscle/joint pain being the most common symptoms. Importantly, LC patients also experienced the ME/CFS hallmark symptom, post-exertional malaise.

Conclusions: Our study not only demonstrates that LC patients exhibit similar symptom clusters to ME/CFS, but that approximately half of LC patients satisfy a diagnosis of ME/CFS. Our findings suggest that current ME/CFS criteria could be adapted to the identification of a subset of LC patients that may facilitate the standardized diagnosis, management and the recruitment for clinical studies in the future.

Source: Ankush Dehlia, Mark A. Guthridge. The persistence of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) after SARS-CoV-2 infection: A systematic review and meta-analysis. Journal of Infection, 2024, 106297, ISSN 0163-4453, https://doi.org/10.1016/j.jinf.2024.106297.
https://www.sciencedirect.com/science/article/pii/S0163445324002317 (Full text)