Tag: 2026

Metabolomic Classification of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome via Explainable Ensemble Learning and Pareto-Guided Feature Selection

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating multisystem illness characterised by post-exertional malaise, non-restorative sleep, and cognitive impairment, yet no objective diagnostic biomarkers have been established. Untargeted plasma metabolomics provides a broad view of the biochemical disturbances underlying ME/CFS; however, the high dimensionality of omics datasets and the limited interpretability of conventional classifiers nevertheless hinder translation into clinical practice. This study evaluates three ensemble classifiers-Explainable Boosting Machine (EBM), XGBoost, and LightGBM-for binary ME/CFS classification using plasma metabolomic and lipidomic profiles from 197 participants (106 ME/CFS; 91 healthy controls; 888 features).

Feature dimensionality was reduced using a Pareto-Guided Recursive Neural Network (PRNN) pipeline. Model performance was assessed via 50-repeat stratified hold-out validation. EBM achieved the highest accuracy (0.909; 95% CI: 0.868-0.949) and area under the receiver operating characteristic curve (AUC: 0.940; 95% CI: 0.909-0.983), with XGBoost and LightGBM performing comparably. Interpretability analyses revealed that pairwise metabolite interaction terms-particularly proline & indole-3-lactate, tyrosine & N-acetylornithine, and maleic acid & arachidic acid-contributed the greatest discriminative signal.

An ablation analysis comparing the full interaction-augmented EBM (AUC = 0.940) with a main-effects-only EBM (AUC = 0.882) confirmed that pairwise metabolite co-variation contributes additional discriminative value beyond individual metabolite levels, implicating amino acid catabolism, tryptophan-kynurenine pathway dysregulation, mitochondrial energy impairment, and lipid remodelling as central pathophysiological features. Global and instance-level explanations jointly demonstrated population-level metabolic signatures alongside individual heterogeneity, highlighting the added clinical value of explainable artificial intelligence (XAI) in metabolomics.

These findings support EBM-based metabolomic profiling as an internally validated approach for ME/CFS classification, subject to external validation, calibration assessment, and prospective testing.

Source: Yagin FH, Korkmaz Y, Colak C, Alzakari SA, Alkhalifa AK, Al-Hashem F, Aghaei M. Metabolomic Classification of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome via Explainable Ensemble Learning and Pareto-Guided Feature Selection. Int J Mol Sci. 2026 Jun 30;27(13):5920. doi: 10.3390/ijms27135920. PMID: 42450188. https://www.mdpi.com/1422-0067/27/13/5920 (Full text)

Australian registry reports poor health and wellbeing in people living with ME/CFS

Abstract:

Introduction: Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a debilitating condition hallmarked by post-exertional malaise accompanied by an array of multisystemic symptoms. Consequently, people living with ME/CFS experience significant health impacts and report poor health-related quality of life (HRQoL). Living with a condition of an area of unmet need, there is a call for a greater understanding of the health impacts of ME/CFS in Australia. Despite growing recognition and awareness, large-scale national comparative investigations using ME/CFS cohorts have not been reported.

Methods: The National Centre for Neuroimmunology and Emerging Diseases houses a significant Australian registry of people with ME/CFS. Self-reported questionnaire data collected from people with ME/CFS and non-fatigued controls (NFC) between 2014 and February 2026 was exported from applications including Research Electronic Data Capture (REDCap) and LimeSurvey. Data was collected pertaining to the sociodemographic background, medical history, symptom presentation (for people with ME/CFS), and validated patient reported outcome measures to assess HRQoL. The questionnaire covered medical history, routine medications, symptom presentation, and HRQoL, using validated tools including the 36-item short form health survey (SF-36). Data was analysed using independent student’s t and chi-square tests, linear regression analysis, principal component analysis (PCA), and k-means clustering. Data was presented as mean and standard deviation or percentages. Statistical analysis was completed using SPSS and RStudio with a significance set at p < 0.05.

Results: Responses were analysed from n = 797 NFC (41.72 ± 13.86 years, 62.6% female) and n = 2,873 people with ME/CFS (44.85 ± 13.77 years, 75.2% female). Participants with ME/CFS fulfilled Fukuda (39.0%), CCC (30.4%) and ICC (30.6%) case definitions. Analysis of symptom presentation differed in both severity and frequency according to the most stringent case definition met; however, this did not predict poor HRQoL outcomes. HRQoL was significantly impaired compared with NFC, and people fulfilling ICC were more likely to report poorer outcomes. Regression analysis revealed the impact of multisystemic symptoms on both physical and mental functioning. K means clustering returned four clusters which differed according to stringent case criteria met, severity and frequency of symptoms.

Conclusion: This large-scale national investigation highlights the significant symptom burden and reduced HRQoL in people with ME/CFS. These findings emphasise the need for tailored clinical approaches and further research into symptom clustering for the purpose of identifying clinical subtypes.

Source: Eaton-Fitch N, Marshall-Gradisnik S. Australian registry reports poor health and wellbeing in people living with ME/CFS. J Transl Med. 2026 Jul 13. doi: 10.1186/s12967-026-08618-9. Epub ahead of print. PMID: 42443918. https://link.springer.com/article/10.1186/s12967-026-08618-9 (Full text available as PDF file)

Association of rapamycin treatment with the modulation of purine metabolism, reduced microglial inflammatory responses, improved mitochondrial energy metabolism, and alleviation of fatigue symptoms in ME/CFS subjects: pilot findings from phase-II observational study

Abstract:

Background and rationale: In our ongoing phase II observational pilot trial, the compounded formulation of low-dose rapamycin significantly reduced fatigue-related clinical symptoms in ME/CFS subjects. Although the underlying molecular mechanism remains unclear, exploring metabolic pathways involving circulating blood-borne factors is warranted. Recent studies suggest that increased levels of purines may exacerbate oxidative stress in ME/CFS patients. It is not known if rapamycin modulates purine biosynthesis and improves disease symptoms.

Methods and results: To address, we performed a comprehensive LCMS-based quantification of purine biosynthetic intermediates in plasma from responder cohort of ME/CFS participants, both at baseline (BSL) and after 90 days of rapamycin therapy (T3). Notably, differential regulation was observed in the enzymatic conversion of inosine monophosphate (IMP) to xanthosine-5-monophosphate (XMP) and hypoxanthine (HPX) between BSL and T3 samples. Flow cytometry assays on PBMCs confirmed that rapamycin reduces IMP dehydrogenase activity, thereby limiting the conversion of IMP to XMP. Further analyses, including mitochondrial oxidative stress assessments, Seahorse OCR following purine supplementation, and flow cytometry indicate that altered purine levels can impair mitochondrial energy metabolism, and may contribute to inflammatory processes in microglia.

Conclusion: Collectively, these findings highlight the therapeutic potential of rapamycin to enhance energy metabolism in patients with ME/CFS.

Major limitations: There is no placebo group, and molecular results are somewhat biased to responders.

Trial registration: CLINICALTRIALS.GOV, NCT06257420. Registered 11 December 2023, https://clinicaltrials.gov/study/NCT06257420.

Source: Gile B, Bulbule S, Toriola MA, Ruan BT, Marium S, Benko A, Grach S, Mueller M, Bateman L, Bell J, Yellman B, Berner J, Chheda B, Kaufman D, Gottschalk G, Roy A. Association of rapamycin treatment with the modulation of purine metabolism, reduced microglial inflammatory responses, improved mitochondrial energy metabolism, and alleviation of fatigue symptoms in ME/CFS subjects: pilot findings from phase-II observational study. J Transl Med. 2026 Jul 10. doi: 10.1186/s12967-026-08575-3. Epub ahead of print. PMID: 42432754. https://link.springer.com/article/10.1186/s12967-026-08575-3 (Full text available as PDF file)

Disrupted glymphatic function and its relationship with sleep and cognitive impairment in ME/CFS assessed via DTI-ALPS

Abstract:

The glymphatic system is a recently discovered brain waste clearance system that is mostly active during sleep and disengaged during wakefulness. Impaired glymphatic function leads to the deposition of metabolic waste products in the brain potentially causing inflammation leading to various symptoms in ME/CFS. While the glymphatic function has been assessed in other neurodegenerative diseases using ‘diffusion tensor imaging along the perivascular space’ (DTI-ALPS), it has not been studied in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS).

This preliminary study investigates glymphatic function in 58 participants (ME/CFS = 31 and healthy controls = 27) using the DTI-ALPS index derived from DTI data acquired with 3 T MRI. The bilateral hemispheric DTI-ALPS index was estimated to assess glymphatic function, and an asymmetry index was calculated to determine interhemispheric asymmetry in glymphatic function.

We found that the global DTI-ALPS index was significantly lower in ME/CFS patients compared to healthy controls (ME/CFS: 1.44 ± 0.086; healthy controls: 1.51 ± 0.11, p = 0.014), indicating reduced glymphatic function in ME/CFS. Examining the hemispheres separately, showed the right hemisphere DTI-ALPS index was lower in ME/CFS than healthy controls (ME/CFS = 1.41 ± 0.097; healthy controls = 1.49 ± 0.12; p = 0.009) but not different on the left. Additionally, we did not find any significant difference in asymmetry index between ME/CFS and healthy controls. We observed an association between the global DTI-ALPS index and severity of ‘sleep disturbance’ (p = 0.013, r = -0.47) and “impaired concentration” (p = 0.026, r = -0.43).

This study demonstrated impaired glymphatic function in ME/CFS which may lead to symptoms such as cognitive dysfunction and sleep disturbance experienced by ME/CFS.

Source: Thapaliya K, Marshall-Gradisnik S, Inderyas M, Barnden L. Disrupted glymphatic function and its relationship with sleep and cognitive impairment in ME/CFS assessed via DTI-ALPS. Front Neurosci. 2026 Jun 19;20:1875420. doi: 10.3389/fnins.2026.1875420. PMID: 42403482; PMCID: PMC13329448. https://pmc.ncbi.nlm.nih.gov/articles/PMC13329448/ (Full text)

Association between light exposure patterns and multidimensional health outcomes in individuals with myalgic encephalomyelitis/chronic fatigue syndrome: findings from an observational cross-sectional cohort study

Abstract:

Background: Light is a major environmental factor regulating circadian rhythms, sleep- wake cycles, and mood-related behaviors. Patients with Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) often experience circadian disruption and poor sleep quality, which severely compromise their quality of life; however, the relationship between light exposure and illness severity remains largely unknown.

Methods: An observational cross-sectional cohort secondary study used collected data from 100 ME/CFS patients and 56 healthy controls to explore the impact of spontaneous light exposure on multidimensional health status and circulating biochemical parameters. Demographic and clinical features were assessed using validated patient-reported outcome measures. Light intensity, wrist temperature, and physical activity were continuously monitored at home over one week using wrist-worn actigraphy. Light intensity during predefined intervals and rhythmic variables of light cycle were calculated. Principal component analysis (PCA) was applied to reduce dimensionality of light variables. Multivariable analysis was performed adjusting for age, sex, body mass index, and physical activity.

Results: Following PCA of the light patterns, two components emerged across groups with high consistency: PC1 (explaining 61.7% of the total variance) reflected higher daytime light and rhythm stability, and PC2 (explaining 16.1%) represented nocturnal/early-morning light and rhythm instability. In ME/CFS patients, light variables were more extensively associated with clinical outcomes measures (FIS-40, PSQI and SF-36) than in healthy controls (all p < 0.05). Furthermore, PC2 was associated with higher levels of VCAM-1 and triglycerides, and lower serotonin concentrations (all p < 0.05). Four distinct light patterns were identified based on PCA scores: nocturnal light, healthy, adverse, and low diurnal light. ME/CFS patients exhibiting the healthy light pattern showed significantly lower fatigue, fewer sleep complaints, reduced autonomic dysfunction, and higher quality of life compared to those with the adverse light pattern (all p < 0.05). No significant differences were observed among healthy controls.

Conclusions: Light exposure patterns show distinct associations with symptom variability in ME/CFS compared to healthy controls. More stable daytime light appears to relate to better symptom profiles, whereas irregular exposure and nocturnal light are linked to poorer health outcomes. Although causality cannot be inferred, these findings highlight light exposure as a potentially modifiable, non-invasive target for behavioral interventions aimed at improving the quality of life in ME/CFS, representing a promising emerging for future translational research.

Source: Cambras T, Domingo JC, Sanmartín-Sentañes R, Alegre-Martín J, Castro-Marrero J. Association between light exposure patterns and multidimensional health outcomes in individuals with myalgic encephalomyelitis/chronic fatigue syndrome: findings from an observational cross-sectional cohort study. J Transl Med. 2026 Jul 3. doi: 10.1186/s12967-026-08556-6. Epub ahead of print. PMID: 42399727. https://link.springer.com/article/10.1186/s12967-026-08556-6 (Full text available as PDF file)

Higher-order brain processes, rather than early processing, underlie sensory problems in ME/CFS: evidence from ERPs

Abstract:

Introduction: Patients with Myalgic Encephalomyelitis (ME)/Chronic Fatigue Syndrome (CFS) experience significant sensory problems that affect their personal, social and occupational life. However, there is no clear understanding of how the sensory problems manifest in ME/CFS. Neuroimaging studies have provided indirect evidence of the involvement of sensory brain areas in ME/CFS. This novel systematically examined the role of early sensory processing and late information processing brain systems in ME/CFS patients.

Methods: The participants consisted of 31 ME/CFS patients and 30 healthy matched controls. Measures of subjective experience of sensory problems as well as event-related brain potentials (ERPs) on an auditory paired click task and an auditory oddball task were collected.

Results: ME/CFS patients reported significantly higher sensory problems compared to the control group. On the ERP measures, the ME/CFS group was not significantly different on the P50 suppression index than the control group. However, the ME/CFS group showed a significantly reduced P300 potential compared with the control group.

Discussion: These findings suggest that the higher-order control-based brain mechanism contributes to the sensory problems experienced by ME/CFS patients. These findings could have profound implications for targeted interventions directed towards higher-order brain systems, rather than the sensory systems, to address challenges related to sensory processing problems in ME/CFS.

Source: Kumar S, Veldhuis A, Yazdani F. Higher-order brain processes, rather than early processing, underlie sensory problems in ME/CFS: evidence from ERPs. Front Med (Lausanne). 2026 Jun 18;13:1842841. doi: 10.3389/fmed.2026.1842841. PMID: 42396162; PMCID: PMC13322831. https://pmc.ncbi.nlm.nih.gov/articles/PMC13322831/ (Full text)

Therapeutic plasma exchange and immunomodulatory strategies in post-infectious syndromes: A review of immune dysregulation in PTLDS, long COVID, ME/CFS, and PANS/PANDAS

Abstract:

Post-infectious syndromes including post-treatment Lyme disease syndrome (PTLDS), long COVID, myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), and pediatric acute-onset neuropsychiatric syndrome (PANS)/pediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS) share overlapping clinical phenotypes characterized by fatigue, cognitive dysfunction, sleep disturbance, and neuropsychiatric symptoms. Increasing evidence suggests that immune dysregulation-including persistent inflammation, autoantibody production, and cellular immune dysfunction-may underlie these conditions.

This narrative review synthesizes peer-reviewed literature describing immune abnormalities across these syndromes and evaluates the rationale for immunomodulatory therapies, including intravenous immunoglobulin (IVIG), rituximab, and therapeutic plasma exchange (TPE). Evidence supporting immune-targeted treatment strategies is strongest in subsets of patients with identifiable immunologic abnormalities. Notably, the phase III RituxME trial in ME/CFS and a phase II trial of TPE in post-COVID condition both failed to demonstrate efficacy in unselected populations, reinforcing the importance of biomarker-guided patient stratification. TPE functions by removing circulating immune complexes, autoantibodies, and inflammatory mediators, and observational data suggest benefit in patients with demonstrable autoantibody burden. Further controlled studies incorporating immunologic phenotyping and early intervention are needed to define the therapeutic role of immune-directed interventions across these conditions.

Source: Kaplan G. Therapeutic plasma exchange and immunomodulatory strategies in post-infectious syndromes: A review of immune dysregulation in PTLDS, long COVID, ME/CFS, and PANS/PANDAS. Transfus Apher Sci. 2026 Jun 26;65(4):104482. doi: 10.1016/j.transci.2026.104482. Epub ahead of print. PMID: 42391726.  https://pubmed.ncbi.nlm.nih.gov/42391726/

Efficacy of Low-Dose Naltrexone in Women With Fibromyalgia Syndrome: A 12-Month Randomised, Double-Blind, Placebo-Controlled Single-Centre Clinical Trial (INNOVA Study)

Abstract:

Background: Low-dose naltrexone (LDN) has been used off-label for fibromyalgia syndrome (FMS) for over a decade, supported by small crossover trials. The INNOVA study evaluated the safety and efficacy of LDN 4.5 mg versus placebo on pain intensity over 12 months in women with FMS.

Methods: In total, 98 women with FMS were randomised to LDN 4.5 mg/day (n = 48) or placebo (n = 50). The primary outcome was change in pain intensity (NRS 0-10) from baseline to 3 months in the intention-to-treat population. Secondary outcomes included functional impairment (FIQR), anxiety-depressive symptoms (DASS-21), cognitive impairment (MISCI), disability (WHODAS 2.0), pathological worry (GAD-7) and impression of change (PGIC/PSIC), assessed at baseline and at 3, 6 and 12 months. Perceived treatment allocation and safety were also assessed.

Results: At 3 months, mean change in pain intensity was -0.33 points with LDN and -0.64 with placebo, with an adjusted between-group difference of 0.49 (p = 0.236, d = 0.19). Secondary outcomes showed minor and inconsistent changes, with low and similar responder rates (p = 0.219-0.954). Exploratory analyses suggested some improvement among participants who believed they had received LDN, although effects were inconsistent. Adverse events, predominantly mild and transient, were reported by 33 (68.8%) participants in LDN and 36 (72%) in placebo, and no treatment-related serious events occurred.

Conclusions: LDN was well tolerated but did not demonstrate a clinically meaningful benefit over placebo for pain-related outcomes, underscoring the need for more effective pharmacological treatments.

Significance statement: This RCT provides the first long-term evidence on the efficacy and safety of LDN in FMS. LDN (4.5 mg), administered as an add-on treatment, has a favourable safety profile, but the findings indicate that it does not produce clinically meaningful improvements in FMS symptoms compared to placebo at short- or long-term follow-up. These findings contribute to the growing body of evidence questioning its clinical utility.

Source: Rodríguez-Freire C, Navarrete J, Rozadilla-Sacanell A, Sanabria-Mazo JP, Del Pino-Gaya B, Borràs X, Feliu-Soler A, Luciano JV. Efficacy of Low-Dose Naltrexone in Women With Fibromyalgia Syndrome: A 12-Month Randomised, Double-Blind, Placebo-Controlled Single-Centre Clinical Trial (INNOVA Study). Eur J Pain. 2026 Jul;30(6):e70321. doi: 10.1002/ejp.70321. PMID: 42385209; PMCID: PMC13322712. https://pmc.ncbi.nlm.nih.gov/articles/PMC13322712/ (Full text)

Exploring the mechanisms of acupuncture in improving cognitive function in post-COVID-19 myalgic encephalomyelitis/chronic fatigue syndrome: study protocol for a randomized controlled trial using multimodal MRI

Abstract:

Background: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a common sequela following COVID-19. Although cognitive dysfunction is one of the most debilitating symptoms in ME/CFS, effective therapies are limited. Acupuncture is an important complementary and alternative therapy for ME/CFS and has been shown to have positive effects on cognitive dysfunction in other diseases. However, the effect and mechanism of acupuncture in treating cognitive dysfunction in post-COVID-19 ME/CFS(PCME/CFS) remain unclear. In this study, we designed a randomized controlled trial to evaluate the efficacy of acupuncture treatment in improving cognitive function in PCME/CFS and to investigate the neural mechanisms of acupuncture using multimodal magnetic resonance imaging (MRI) techniques.

Methods: A total of 129 patients and 30 healthy controls (HCs) will be enrolled. The 129 patients with PCME/CFS will be randomly assigned in a 1:1:1 ratio to a verum acupuncture (VA), sham acupuncture (SA), or a waitlist control group. Participants in the VA and SA groups will receive three sessions of treatment per week for 8 weeks, while patients in the waitlist control group will be treated after the 8-week waiting period. The primary outcome is the change in the Symbol Digit Modalities Test (SDMT) score from baseline to week 8. The secondary outcome measures include changes from baseline to endpoint (week 8) in cognitive performance as assessed by the Digit Span Test (DST), Trail Making Test (TMT), Rey Auditory Verbal Learning Test (RAVLT), Rey-Osterrieth complex figure test (RCFT), Stroop Color and Word Test (SCWT), phonemic fluency test, category fluency test, action fluency test, and 30-item Boston Naming Test (BNT-30). In addition, changes in hippocampal metabolites and resting-state functional connectivity(RSFC) will be examined using 1H-magnetic resonance spectroscopy(1H-MRS) and functional MRI (fMRI), respectively. Moreover, the Multidimensional Fatigue Inventory (MFI-20), Pittsburgh Sleep Quality Index (PSQI), Generalized Anxiety Disorder 7-item scale (GAD-7), 24-item Hamilton Depression Scale (HAMD-24), and 36-Item Short Form Survey (SF-36) will also be assessed at baseline and week 8.

Discussion: The results of this study will provide preliminary evidence regarding the efficacy of acupuncture therapy in improving cognitive function in PCME/CFS and will explore whether acupuncture improves cognitive function in this disease by modulating metabolism and RSFC in the hippocampus.

Clinical trial registration: www.clinicaltrials.gov, identifier: NCT07357688.

Source: Luo T, Luo Y, Huang L, Jin H, An Y, Huang J, Luo K, Guo Y, Wang D, Liu D, Wu X. Exploring the mechanisms of acupuncture in improving cognitive function in post-COVID-19 myalgic encephalomyelitis/chronic fatigue syndrome: study protocol for a randomized controlled trial using multimodal MRI. Front Neurol. 2026 Jun 3;17:1793397. doi: 10.3389/fneur.2026.1793397. PMID: 42383026; PMCID: PMC13318089. https://pmc.ncbi.nlm.nih.gov/articles/PMC13318089/ (Full text)

Exploring differences in protein cargo of extracellular vesicles from ME/CFS patient plasma compared to healthy controls

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a chronic and debilitating disease characterized by post-exertional malaise, fatigue and pain. Yet, its underlying biological mechanisms remain poorly understood. Extracellular vesicles (EVs) are nanoparticles carrying biological cargo and are involved in cell-cell communication. Plasma EVs reflect several disease states and may serve as minimally invasive biomarkers. In this exploratory study, we characterized the plasma EV profiles of ME/CFS patients (N = 49) and healthy controls (N = 50), by enriching for EVs by size-exclusion chromatography coupled to high-resolution quantitative proteomics.

The ME/CFS patients had significantly higher concentrations of EVs than healthy controls. Among the 424 detected proteins included for analyses, 11 had different levels in EVs from ME/CFS patients. The ME/CFS associated EV proteins appear to mainly originate from erythroid cells, hepatocytes and plasma B cells, based on their tissue expression. Albeit differences in EV protein levels did not withstand correction for multiple testing, our study is the largest to date, thereby encouraging future investigations on the role of EV and its cargo in ME/CFS.

Source: Rydland A, Yran ES, Nyman TA, Strand EB, Trøseid AS, Øvstebø R, Heinicke F, Lie BA, Viken MK. Exploring differences in protein cargo of extracellular vesicles from ME/CFS patient plasma compared to healthy controls. Biochem Biophys Rep. 2026 Jun 20;47:102679. doi: 10.1016/j.bbrep.2026.102679. PMID: 42375682; PMCID: PMC13312568. https://pmc.ncbi.nlm.nih.gov/articles/PMC13312568/ (Full text)