Tag: Systrom

Shared autonomic phenotype of long COVID and myalgic encephalomyelitis/chronic fatigue syndrome

Abstract:

Introduction: Long COVID and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) are relatively common and disabling multisystem disorders that share overlapping features, including post-infectious onset and similar clinical manifestations such as brain fog, fatigue, muscle pain, and dysautonomia with orthostatic intolerance. These similarities suggest that Long COVID and ME/CFS may share common pathophysiological mechanisms, though the underlying mechanisms remain poorly understood, partly due to the difficulty in quantifying many of the symptoms.

Materials and methods: This retrospective study evaluated Long COVID and pre-COVID ME/CFS patients who completed autonomic testing between 2018 and 2023 at the Brigham and Women’s Faulkner Hospital Autonomic Laboratory. The evaluations included autonomic tests (Valsalva maneuver, deep breathing, tilt-table test, and sudomotor function) with capnography and transcranial Doppler monitoring of cerebral blood flow velocity (CBFv) in the middle cerebral artery, neuropathic assessment through skin biopsies for small fiber neuropathy (SFN), invasive cardiopulmonary exercise testing (ICPET), and laboratory analyses covering metabolic, inflammatory, autoimmune, and hormonal profiles.

Results: A total of 143 Long COVID and 170 ME/CFS patients were analyzed and compared to 73 healthy controls and 290 patients with hypermobile Ehlers-Danlos syndrome (hEDS). Tests revealed extensive similarities between Long COVID and ME/CFS, including reduced orthostatic CBFv (92%/88% in Long COVID/ME/CFS), mild-to-moderate widespread autonomic failure (95%/89%), presence of SFN (67%/53%), postural tachycardia syndrome (POTS) (22%/19%), neurogenic orthostatic hypotension (15%/15%) and preload failure (96%/92%, assessed in 25/66 Long COVID/ME/CFS). Patients with hEDS exhibited more severe peripheral neurodegeneration compared to the other groups. Laboratory tests did not distinguish between the conditions.

Conclusion: Both Long COVID and ME/CFS demonstrate dysregulation in cerebrovascular blood flow, autonomic reflexes, and small fiber neuropathy, suggesting that these conditions may share a common underlying pathophysiology. However, differing distributions of findings in patients with hEDS raise the question of whether these conditions represent distinct but overlapping syndromes or reflect a shared underlying pathway. Further research is required to clarify the relationship between these conditions and the potential underlying pathophysiological mechanisms.

Source: Novak P, Systrom DM, Witte A, Marciano SP, Felsenstein D, Milunsky JM, Milunsky A, Krier J, Fishman MC. Shared autonomic phenotype of long COVID and myalgic encephalomyelitis/chronic fatigue syndrome. PLoS One. 2026 Jan 23;21(1):e0341278. doi: 10.1371/journal.pone.0341278. PMID: 41576003. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0341278 (Full text)

Pyridostigmine and low-dose naltrexone for ME/CFS: study protocol for the Life Improvement Trial (LIFT), a randomized, double-blind, placebo-controlled clinical trial

Abstract:

Background: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex, chronic disease with no FDA-approved treatments. This report describes a protocol for the Life Improvement Trial (LIFT), a randomized, double-blind, placebo-controlled clinical trial investigating the impact of low-dose naltrexone (LDN) and pyridostigmine (Mestinon) on physiological response, symptoms, and functionality of ME/CFS patients.

Methods: Participants (target n = 160) are recruited through clinics at Massachusetts General Hospital and Brigham and Women’s Hospital, and through Open Medicine Foundation’s StudyME registry. They are then randomized into one of four arms: LDN/pyridostigmine, LDN/placebo, placebo/pyridostigmine, placebo/placebo. Treatment is administered for 13 weeks after an initial screening period of up to 4 weeks. Primary outcomes are FUNCAP-55 score, peak oxygen utilization, heart rate recovery, and oxygen uptake efficiency slope. Secondary outcomes are scores from DSQ-PEM and PROMIS-29 surveys, DANA Brain Vital score, step count, heart rate, and heart rate variability.

Discussion: The results of this trial will provide novel insights into the efficacy of and predictors of response to LDN and pyridostigmine in ME/CFS. This may inform future treatment strategies for ME/CFS. The trial will also validate what primary and secondary outcomes to use in similar clinical trials.

Source: Danielle Meadows, Johanna Squires, Joshua Dibble et al. Pyridostigmine and low-dose naltrexone for ME/CFS: study protocol for the Life Improvement Trial (LIFT), a randomized, double-blind, placebo-controlled clinical trial, 04 March 2025, PREPRINT (Version 1) available at Research Square [https://doi.org/10.21203/rs.3.rs-5626167/v1]

Exercise Pathophysiology in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Long COVID: Commonalities Detected by Invasive Cardiopulmonary Exercise Testing

Abstract:

Rationale: There is substantial overlap of exertional symptoms in Long COVID (LC) and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) including intractable fatigue, post-exertional malaise (PEM), and orthostatic intolerance, but very little objective data liking the two. This study compares exercise pathophysiology in the two disorders and normal controls using invasive cardiopulmonary exercise testing (iCPET).

Methods: Between January 2019 and December 2024, 1,518 patients underwent a clinical iCPET at Brigham and Women’s Hospital. Exclusion criteria included morbid obesity (BMI>40 kg/m2), severe anemia ([Hb]<9.0 g/dL), elite athletes (peak VO2 (pVO2)>120% predicted), sub-maximum effort (RER<1.05), a primary pulmonary mechanical limit (VE @ AT/MVV>0.7), and comorbidities such as active/treated cancer, interstitial lung disease, or other respiratory related diseases. iCPET results from 438 ME/CFS patients, 73 LC patients, and 43 symptomatic but otherwise normal controls were analyzed. pV02, peak cardiac output (pQc), peak right atrial pressure (pRAP), peak systemic oxygen extraction (pSOE; Ca-vO2/[Hb]), and ventilatory inefficiency (VE/VCO2 slope) were compared among groups. Statistical significance was determined using Kruskal-Wallis tests for global comparisons, with post-hoc Dunn tests for pairwise group comparisons. Holm-Bonferroni adjustments were applied to control for multiple comparisons.

Results: LC and ME/CFS displayed reduced pVO2 % predicted compared to controls (LC: 78.4 ± 18%, ME/CFS: 78.1 ± 17%, Controls: 97.5 ± 10%, P≤0.0001). Reduced pQc % predicted was also observed compared to controls (LC: 91.1 ± 18%, ME/CFS: 96.3%, Controls: 101 ± 11%, P≤0.001). pRAP were significantly less compared to controls (LC: 1.1 ± 3.1 mmHg, ME/CFS: 1.3 ± 2.8 mmHg, Controls: 3.6 ± 3.4 mmHg, P≤0.001). Significant reductions in pSOE were seen for LC and ME/CFS (LC: 0.81 ± 0.1, ME/CFS: 0.81 ± 0.1, Controls, 0.91 ± 0.1, P≤0.0001). The only measure with no significant difference between disease and control was VE/VCO2 slope (LC: 31.4 ± 8.4, ME/CFS: 31.6 ± 6.9, Controls: 32.0 ± 6.7, P≥0.261). Most interestingly, no significant differences were seen between the two diseases for any of the analyzed measures (P≥0.245).

Conclusions: We report the largest cohort of ME/CFS and LC investigated with iCPET to date. ME/CFS and LC share symptomatic, reduced aerobic capacity at peak exercise, which is driven by preload insufficiency and impaired systemic O2 extraction, the latter compatible with peripheral left-to-right shunting and/or limb skeletal muscle dysfunction. These findings should drive future diagnostics and personalized medicine in both diseases. We hope these data inform the pending prospective NIH RECOVER iCPET study of LC.

Source: J. Squires, S. Palwayi, P. Li, W. Xiao, K. LeWine, S.W. Johnson, D. Felsenstein, A.B. Waxman, and D.M. Systrom. Exercise Pathophysiology in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Long COVID: Commonalities Detected by Invasive Cardiopulmonary Exercise Testing [abstract]. Am J Respir Crit Care Med 2025;211:A7881. https://www.atsjournals.org/doi/​10.1164/ajrccm.2025.211.Abstracts.A7881

Mismatch between subjective and objective dysautonomia

Abstract:

Autonomic symptom questionnaires are frequently used to assess dysautonomia. It is unknown whether subjective dysautonomia obtained from autonomic questionnaires correlates with objective dysautonomia measured by quantitative autonomic testing. The objective of our study was to determine correlations between subjective and objective measures of dysautonomia.

This was a retrospective cross-sectional study conducted at Brigham and Women’s Faulkner Hospital Autonomic Laboratory between 2017 and 2023 evaluating the patients who completed autonomic testing. Analyses included validated autonomic questionnaires [Survey of Autonomic Symptoms (SAS), Composite Autonomic Symptom Score 31 (Compass-31)] and standardized autonomic tests (Valsalva maneuver, deep breathing, sudomotor, and tilt test). The autonomic testing results were graded by a Quantitative scale for grading of cardiovascular reflexes, sudomotor tests and skin biopsies (QASAT), and Composite Autonomic Severity Score (CASS). Autonomic testing, QASAT, CASS, and SAS were obtained in 2627 patients, and Compass-31 in 564 patients.

The correlation was strong between subjective instruments (SAS vs. Compass-31, r = 0.74, p < 0.001) and between objective instruments (QASAT vs. CASS, r = 0.81, p < 0.001). There were no correlations between SAS and QASAT nor between Compass-31 and CASS. There continued to be no correlations between subjective and objective instruments for selected diagnoses (post-acute sequelae of COVID-19, n = 61; postural tachycardia syndrome, 211; peripheral autonomic neuropathy, 463; myalgic encephalomyelitis/chronic fatigue syndrome, 95; preload failure, 120; post-treatment Lyme disease syndrome, 163; hypermobile Ehlers-Danlos syndrome, 213; neurogenic orthostatic hypotension, 86; diabetes type II, 71, mast cell activation syndrome, 172; hereditary alpha tryptasemia, 45).

The lack of correlation between subjective and objective instruments highlights the limitations of the commonly used questionnaires with some patients overestimating and some underestimating true autonomic deficit. The diagnosis-independent subjective–objective mismatch further signifies the unmet need for reliable screening surveys. Patients who overestimate the symptom burden may represent a population with idiosyncratic autonomic-like symptomatology, which needs further study. At this time, the use of autonomic questionnaires as a replacement of autonomic testing cannot be recommended.

Source: Novak, P., Systrom, D., Marciano, S.P. et al. Mismatch between subjective and objective dysautonomia. Sci Rep 14, 2513 (2024). https://doi.org/10.1038/s41598-024-52368-x https://www.nature.com/articles/s41598-024-52368-x (Full text)

Investigation into the Plasma Proteome Signature in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS)

Abstract:

Background: ME/CFS is a complex disease with unclear etiology. Current diagnostic criteria lack objective laboratory measures.

Aims: This study aimed to investigate the plasma proteomic profile of ME/CFS patients and determine any differentially expressed proteins compared to controls.

Methods: Plasma samples obtained from 19 ME/CFS patients and 9 controls underwent analysis (Somalogic, Inc, CO). The ME/CFS patients met the National Academy of Medicine criteria for the disease. Samples were collected from a mixed venous compartment. Statistical analysis and a Mixed Graphical Model were used to identify candidate biomarker.

Results: Among ~7000 proteins detected, ~400 were differentially expressed between patients and controls (False Discovery Rate<0.05 and Absolute Fold Change ≥1.5). Selectin E (SELE), ATP Synthase Subunit F6 (ATP5PF), and Transcobalamin 2 (TCN2) were identified as top candidates. A classifier of these proteins in pulmonary artery blood of patients were distinguishable from controls (AUC =0.99).

Conclusion: The study highlighted potential biomarkers for ME/CFS, the top candidates of which are involved in inflammation, cellular energy metabolism, and Vitamin B12 transport. The plasma proteomic signature identifies ME/CFS from normals and suggests that the disease’s pathophysiology is driven by abnormalities of aerobic metabolism, vascular dysregulation, and Vitamin B12 metabolism.

Source: Johanna Squires, Sarra Al-Zayer, Peng Li, Wenzhong Xiao, David Systrom. Investigation into the Plasma Proteome Signature in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS). European Respiratory Journal Sep 2023, 62 (suppl 67) PA2960; DOI: 10.1183/13993003.congress-2023.PA2960 https://erj.ersjournals.com/content/62/suppl_67/PA2960.abstract

Myalgic Encephalomyelitis-Chronic Fatigue Syndrome Common Data Element item content analysis

Abstract:

Introduction: Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a multisystem chronic disease estimated to affect 836,000-2.5 million individuals in the United States. Persons with ME/CFS have a substantial reduction in their ability to engage in pre-illness levels of activity. Multiple symptoms include profound fatigue, post-exertional malaise, unrefreshing sleep, cognitive impairment, orthostatic intolerance, pain, and other symptoms persisting for more than 6 months. Diagnosis is challenging due to fluctuating and complex symptoms. ME/CFS Common Data Elements (CDEs) were identified in the National Institutes of Health (NIH) National Institute of Neurological Disorders and Stroke (NINDS) Common Data Element Repository. This study reviewed ME/CFS CDEs item content.

Methods: Inclusion criteria for CDEs (measures recommended for ME/CFS) analysis: 1) assesses symptoms; 2) developed for adults; 3) appropriate for patient reported outcome measure (PROM); 4) does not use visual or pictographic responses. Team members independently reviewed CDEs item content using the World Health Organization International Classification of Functioning, Disability and Health (ICF) framework to link meaningful concepts.

Results: 119 ME/CFS CDEs (measures) were reviewed and 38 met inclusion criteria, yielding 944 items linked to 1503 ICF meaningful concepts. Most concepts linked to ICF Body Functions component (b-codes; n = 1107, 73.65%) as follows: Fatiguability (n = 220, 14.64%), Energy Level (n = 166, 11.04%), Sleep Functions (n = 137, 9.12%), Emotional Functions (n = 131, 8.72%) and Pain (n = 120, 7.98%). Activities and Participation concepts (d codes) accounted for a smaller percentage of codes (n = 385, 25.62%). Most d codes were linked to the Mobility category (n = 69, 4.59%) and few items linked to Environmental Factors (e codes; n = 11, 0.73%).

Discussion: Relatively few items assess the impact of ME/CFS symptoms on Activities and Participation. Findings support development of ME/CFS-specific PROMs, including items that assess activity limitations and participation restrictions. Development of psychometrically-sound, symptom-based item banks administered as computerized adaptive tests can provide robust assessments to assist primary care providers in the diagnosis and care of patients with ME/CFS.

Source: Slavin MD, Bailey HM, Hickey EJ, Vasudevan A, Ledingham A, Tannenbaum L, Bateman L, Kaufman DL, Peterson DL, Ruhoy IS, Systrom DM, Felsenstein D, Kazis LE. Myalgic Encephalomyelitis-Chronic Fatigue Syndrome Common Data Element item content analysis. PLoS One. 2023 Sep 12;18(9):e0291364. doi: 10.1371/journal.pone.0291364. PMID: 37698999. https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0291364 (Full text)

ME/CFS Pathophysiology Investigated by Invasive Cardiopulmonary Exercise Testing and Autonomic Function Testing

Abstract

Introduction: Mechanisms underlying exercise and orthostatic intolerance in myalgic encephalomyelitis/chronic
fatigue syndrome (ME/CFS) have been uncovered by invasive cardiopulmonary exercise testing (iCPET) and
autonomic function testing (AFT), but the relationships between the two are not known. This study aims to determine
if there is overlap of cardiovascular and respiratory pathophysiology in patients who have undergone both
tests.

Methods: Between January 2017 and April 2022, 62 patients were identified with a contemporary iCPET and
AFT. Key variables from the iCPET included peak oxygen uptake (pVO2), cardiac output (pQc), right atrial pressure
(pRAP), and systemic oxygen extraction (Ca-vOy/Hgb) at peak exercise. Key variables from the autonomic testing
included epidermal and sweat gland small fiber neurite density, electrochemical skin conductance, and change in
heart rate (AH) and end tidal carbon dioxide (AETCO2) from supine to upright during the tilt table test
(TTT).

Results: All 62 patients demonstrated preload failure (pRAP < 6.5mmHg). Of this group, 54 patients (87.1%) fulfilled NAM criteria for ME/CFS, with 32 testing positive (59.3%) for small fiber neuropathy (SFN) using either morphological and/or functional testing. Significant correlations were found between pVOg and both AH (r=-0.439. P<0.05) and AETCO, (r=0.474, P<0.05) during TTT. The same tilt table variables were found to be significantly correlated with pQc (r=-0.365, P<0.05 and r=0.351, P<0.05) from the iCPET. It should be noted that 8 of the ME/CFS SFN patients (25%) fulfilled diagnostic criteria for postural orthostatic tachycardia syndrome (POTS) based on the tilt table test.

Conclusion: Decreased oxygen uptake and cardiac output at peak exercise during iCPET correlated with a greater change in heart rate and ETCO from supine to upright during TTT. There appears to be significant overlap of cardiopulmonary pathophysiology in ME/CFS underlying exercise and orthostatic symptoms.

Source: J. Squires, K. Wichmann Madsen, M.C. Stovall, S. Al-Zayer, W. Xiao, C.-J. Chang, P. Novak, D.M. Systrom. ME/CFS Pathophysiology Investigated by Invasive Cardiopulmonary Exercise Testing and Autonomic Function Testing. American Journal of Respiratory and Critical Care Medicine 2023;207:A2996. https://www.atsjournals.org/doi/abs/10.1164/ajrccm-conference.2023.207.1_MeetingAbstracts.A2996

Sex Differences in Hemodynamic Response to Exercise in Patients With Myalgic Encephalomyelitis: Insights From Invasive Cardiopulmonary Exercise Testing

Abstract:

Abstract available online: https://www.atsjournals.org/doi/10.1164/ajrccm-conference.2023.207.1_MeetingAbstracts.A2995

Source: K. Wichmann Madsen, J. Squires, M.C. Stovall, S. Al-Zayer, C.-J. Chang, W. Xiao, R. Pari, P. Joseph, D.M. Systrom. Sex Differences in Hemodynamic Response to Exercise in Patients With Myalgic Encephalomyelitis: Insights From Invasive Cardiopulmonary Exercise Testing. American Journal of Respiratory and Critical Care Medicine 2023;207:A2995 https://www.atsjournals.org/doi/10.1164/ajrccm-conference.2023.207.1_MeetingAbstracts.A2995

Exercise Pathophysiology in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Post-Acute Sequelae of SARS-CoV-2: More in Common Than Not?

Abstract:

Topic importance: Post-Acute Sequelae of SARS-CoV-2 (PASC) is a long-term consequence of acute infection from coronavirus disease 2019 (COVID-19). Clinical overlap between PASC and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) has been observed, with shared symptoms including intractable fatigue, postexertional malaise, and orthostatic intolerance. The mechanistic underpinnings of such symptoms are poorly understood.

Review findings: Early studies suggest deconditioning as the primary explanation for exertional intolerance in PASC. Cardiopulmonary exercise testing (CPET) reveals perturbations related to systemic blood flow and ventilatory control associated with acute exercise intolerance in PASC, which are not typical of simple detraining. Hemodynamic and gas exchange derangements in PASC have substantial overlap with those observed with ME/CFS, suggestive of shared mechanisms.

Summary: This review aims to illustrate exercise pathophysiologic commonalities between PASC and ME/CFS that will help guide future diagnostics and treatment.

Source: Joseph P, Singh I, Oliveira R, Capone CA, Mullen MP, Cook DB, Stovall MC, Squires J, Madsen K, Waxman AB, Systrom DM. Exercise Pathophysiology in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Post-Acute Sequelae of SARS-CoV-2: More in Common Than Not? Chest. 2023 Apr 11:S0012-3692(23)00502-0. doi: 10.1016/j.chest.2023.03.049. Epub ahead of print. PMID: 37054777; PMCID: PMC10088277. https://pubmed.ncbi.nlm.nih.gov/37054777/

Neurovascular Dysregulation and Acute Exercise Intolerance in ME/CFS: A Randomized, Placebo-Controlled Trial of Pyridostigmine

Abstract:

Background: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is characterized by intractable fatigue, post-exertional malaise, and orthostatic intolerance, but its pathophysiology is poorly understood. Pharmacologic cholinergic stimulation was used to test the hypothesis that neurovascular dysregulation underlies exercise intolerance in ME/CFS.

Research Question: Does neurovascular dysregulation contribute to exercise intolerance in ME/CFS and can its treatment improve exercise capacity?

Methods: Forty-five subjects with ME/CFS were enrolled in a single-center, randomized, double-blind, placebo-controlled trial. Subjects were assigned in a 1:1 ratio to receive a 60 mg dose of oral pyridostigmine or placebo after an invasive cardiopulmonary exercise test (iCPET). A second iCPET was performed 50 minutes later. The primary end point was the difference in peak exercise oxygen uptake (VO2). Secondary end points included exercise pulmonary and systemic hemodynamics and gas exchange.

Results: Twenty-three subjects were assigned to pyridostigmine and 22 to placebo. The peak VO2 increased after pyridostigmine but decreased after placebo (13.3 ± 13.4 mL/min vs. -40.2 ± 21.3 mL/min, P<0.05). The treatment effect of pyridostigmine was 53.6 mL/min (95% CI, -105.2 to -2.0). Peak versus rest VO2 (25.9 ± 15.3 mL/min vs. -60.8 ± 25.6 mL/min, P<0.01), cardiac output (-0.2 ± 0.6 L/min vs. -1.9 ± 0.6 L/min, P<0.05), and RAP (1.0 ± 0.5 mm Hg vs. -0.6 ± 0.5 mm Hg, P<0.05) were greater in the pyridostigmine group compared to placebo.

Interpretation: Pyridostigmine improves peak VO2 in ME/CFS by increasing cardiac output and right ventricular filling pressures. Worsening peak exercise VO2, Qc, and RAP after placebo may signal the onset of post-exertional malaise. We suggest treatable neurovascular dysregulation underlies acute exercise intolerance in ME/CFS.

Abbreviations List: Ca-vO2 (arterial-venous oxygen content difference), iCPET (Invasive cardiopulmonary exercise test), MAP (Mean arterial pressure), mPAP (Mean pulmonary artery pressure), ME/CFS (Myalgic encephalomyelitis/chronic fatigue syndrome), PASC (Post-acute sequelae of SARS-CoV-2 infection), PAWP (Pulmonary arterial wedge pressure), POTS (Postural orthostatic tachycardia syndrome), Qc (Cardiac output), RAP (Right atrial pressure), SE (Standard error), SFN (Small fiber neuropathy), VE/VCO2 (Ventilatory efficiency), VO2 (Oxygen uptake)

Source: Phillip Joseph, MD, Rosa Pari, MD, Sarah Miller, BS, Arabella Warren, BS, Mary Catherine Stovall, BS, Johanna Squires, MSc, Chia-Jung Chang, PhD, Wenzhong Xiao, PhD, Aaron B. Waxman, MD, PhD, David M. Systrom, MD. Neurovascular Dysregulation and Acute Exercise Intolerance in ME/CFS: A Randomized, Placebo-Controlled Trial of Pyridostigmine. Chest, Published: May 05, 2022. DOI: https://doi.org/10.1016/j.chest.2022.04.146