Tag: fibromyalgia

Knowing or not knowing: the practical and moral complexity of diagnostic-seeking pathways in situations of medical uncertainty

Abstract:

In this paper, we discuss the practical and moral complexities of diagnostic-seeking pathways for three uncertain medical conditions: fibromyalgia, myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), and long COVID. We analyse qualitative data collected in the UK between 2023 and 2025, comprising in-depth interviews with medical professionals, researchers, and patients, as well as documentary sources.

Drawing on the anthropology and sociology of diagnosis, this paper discusses how chronic illness can be marked by challenging and unstable pathways, influenced by the organisation of the medical system and the resources patients have to navigate it. Diagnoses further do not guarantee a solution to the condition, and can, on the other hand, produce stigma. Medical professionals recognise the uncertain nature of these conditions and emphasise how diagnosis can play an instrumental role in providing patients with access to therapies, benefits, or acceptance. Patients discuss the complexity of the strategies they deploy not only to obtain a diagnosis but also to navigate the practical and moral complexities associated with their condition.

Analysing the practical and moral complexity of diagnostic-seeking pathways represents a way to enrich anthropological reflections on diagnosis by demonstrating how this key concept of biomedicine is strongly influenced by social, economic, and moral, as well as biological, factors.

Source: Greco C, Cross S. Knowing or not knowing: the practical and moral complexity of diagnostic-seeking pathways in situations of medical uncertainty. Anthropol Med. 2026 Sep 25:1-16. doi: 10.1080/13648470.2026.2709278. Epub ahead of print. PMID: 42788232. https://www.tandfonline.com/doi/full/10.1080/13648470.2026.2709278 (Full text)

DNA methylation: unifying framework for complex chronic conditions

Abstract:

Complex chronic conditions represent a growing health burden that is poorly understood and inadequately managed within current health systems. This review focuses on the potential of epigenetic DNA methylation to provide a pathway for better understanding of four closely related conditions: myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), long COVID (LC), fibromyalgia (FM), and hypermobile Ehlers-Danlos syndrome (hEDS).

These conditions have extensive overlapping symptoms, suggesting shared underlying pathophysiological mechanisms. Epigenetic regulation, particularly DNA methylation, provides a powerful framework for comparative and longitudinal studies across these clinically overlapping conditions.

Here, we synthesise evidence from current DNA methylation studies in ME/CFS, LC, and FM, and consider how an integrated cross-condition approach could advance mechanistic insight, enable diagnostic stratification, and improve patient outcomes.

Source: Sharma S, Rodger EJ, Chatterjee A, Tate WP. DNA methylation: unifying framework for complex chronic conditions. Trends Genet. 2026 Sep 24:S0168-9525(26)00221-0. doi: 10.1016/j.tig.2026.09.001. Epub ahead of print. PMID: 42786072. https://www.cell.com/trends/genetics/fulltext/S0168-9525(26)00221-0 (Full text)

Micronutrition as a Therapeutic Strategy for Mitochondrial Dysfunction in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Fibromyalgia: A Narrative Review

Abstract:

Fibromyalgia and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) are chronic multisystem disorders characterized by persistent fatigue, pain, cognitive dysfunction, sleep disturbances, and reduced quality of life. Increasing evidence implicates mitochondrial dysfunction, oxidative and nitrosative stress, immune dysregulation, and altered redox and nicotinamide adenine dinucleotide (NAD+) metabolism as interconnected mechanisms contributing to fatigue, although the strength of evidence varies across these pathways. Micronutrients are essential components of mitochondrial bioenergetics, antioxidant defense, and immune-metabolic regulation.

This narrative review critically examines the mechanistic and clinical evidence supporting mitochondrial-oriented micronutritional interventions in fibromyalgia and ME/CFS, including NAD+ precursors, B-complex vitamins, magnesium, coenzyme Q10, alpha-lipoic acid, GlyNAC, L-carnitine, pyrroloquinoline quinone, taurine, and creatine. Mechanistic plausibility is distinguished from clinical efficacy, as disease-specific randomized controlled evidence remains limited for several interventions. We further discuss biomarkers, metabolic phenotyping, and precision nutrition within a systems-based micronutrition framework.

Finally, we present the rationale for a future randomized, double-blind, placebo-controlled trial in fibromyalgia patients with clinically significant fatigue, which is planned for 2027, subject to ethics approval and prospective registration, as a strategy for future clinical validation.

Source: Abanades S, Fernández I, Capdevila N, Cardona F. Micronutrition as a Therapeutic Strategy for Mitochondrial Dysfunction in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Fibromyalgia: A Narrative Review. Nutrients. 2026 Aug 19;18(16):2702. doi: 10.3390/nu18162702. PMID: 42654282. https://www.mdpi.com/2072-6643/18/16/2702 (Full text)

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)

Shared genetic risk between functional somatic syndromes, internalizing disorders, and immune-mediated diseases: a twin-sibling study

Abstract:

Functional somatic syndromes frequently co-occur with internalizing disorders such as anxiety disorders and major depressive disorder. Both show familial associations with immune-mediated diseases. Here, we estimate genetic and environmental contributions to functional somatic syndromes and their overlap with immune-mediated diseases, with internalizing disorders included for comparison.

The study sample consisted of 6,097,372 Swedish twins, full siblings, and half-siblings born between 1945 and 2003. From nationwide registers covering inpatient, outpatient and primary care, we extracted ICD diagnoses of myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), fibromyalgia (FM), irritable bowel syndrome (IBS), major depression, anxiety disorders, and immune-mediated diseases (consisting of autoimmune and autoinflammatory diseases).

We used bivariate twin-sibling structural equation modeling to estimate genetic and environmental correlations. We found that the heritability of functional somatic syndromes and internalizing disorders ranged from 15 to 44%, with the unique environment explaining 49-84% of the variance. We estimated the heritability of immune-mediated diseases at 37% (95% CI 36-38%), with a unique environmental component of 63% (95% CI 62-63%). Regarding the genetic correlations with immune-mediated diseases, fibromyalgia showed the strongest genetic correlation (rA = 0.52, 95% CI 0.45-0.63), IBS, ME/CFS, and major depression showed more modest genetic correlations (rA range 0.19-0.29), and anxiety disorders showed minimal genetic correlation (rA = 0.04, 95% CI 0.00-0.08).

In summary, fibromyalgia, and to a lesser degree other functional somatic syndromes and major depression, share genetic risk factors with immune-mediated diseases. These findings suggest that immune-related genetic risk factors contribute to the etiology of fibromyalgia and, to a lesser extent, other functional disorders and major depression.

Source: Steen OD, Ohlsson H, van Ockenburg SL, Kendler KS, Rosmalen JGM, Sundquist K, van Loo HM. Shared genetic risk between functional somatic syndromes, internalizing disorders, and immune-mediated diseases: a twin-sibling study. Brain Behav Immun. 2026 May 25:106837. doi: 10.1016/j.bbi.2026.106837. Epub ahead of print. PMID: 42190845. https://www.sciencedirect.com/science/article/pii/S0889159126005854 (Full text)

Myalgic encephalomyelitis/chronic fatigue syndrome and fibromyalgia – overlap, differences, and emerging insights

Abstract:

Background: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and fibromyalgia (FM) are debilitating chronic illnesses with considerable symptom overlap. Their symptoms include profound fatigue, widespread pain, post-exertional deterioration, sleep disturbance, dysautonomia, and cognitive impairment. These illnesses frequently co-occur; ME/CFS often develops first, particularly after infection. This overlap creates a diagnostic grey area and contributes to severe reductions in quality of life. Despite these shared features, key distinctions remain essential. ME/CFS is characterised by post-exertional neuroimmune exhaustion (PENE)/post-exertional malaise (PEM), a hallmark of post-exertional worsening and multisystem involvement. Contrastingly, FM centres on chronic widespread pain and symptom variability. It is not characterised by PEM/PENE or the same extent of system dysfunction as ME/CFS. Both disorders lack a definitive biomarker as of 2025. Thus, diagnosis remains clinical and supported by objective tests where available.

Main body: Although immune dysregulation is common in patients with each condition, distinct immune signatures have been observed. ME/CFS is characterised by fluctuating pro- and anti-inflammatory cytokine levels and a frequent reduction in natural killer (NK) cell function; this is consistent with immune exhaustion. Patients with FM exhibit elevated IL-6, IL-17 A, and IL-4 levels, and a broader immune imbalance linked to pain amplification rather than immune collapse. Viral infections do not directly cause either condition, but commonly act as triggers. Shared mechanisms, such as spinal reflex arc activation and microglial sensitisation, suggest a common pathway mediated by proprioceptor-induced microglial activation for chronic pain. ME/CFS causes autoimmunity-like processes, whereas evidence of autoimmune drivers for FM is limited. Gut microbiome studies have revealed reduced microbial diversity in patients with ME/CFS. Moreover, the two disorders are characterised by shared, yet distinct, microbial alterations.

Conclusion: Given the chronic and debilitating nature of ME/CFS and FM, prevention and early intervention remain crucial, but understudied. Health education, workplace adaptations, and early diagnostic pathways may substantially reduce the disease burden. Many patients are outside formal healthcare systems. Therefore, digital tools such as symptom-tracking apps, biosensors, remote testing, and assistive technologies are becoming central to disease management and monitoring. These approaches support a transdiagnostic, patient-centred model capable of addressing both conditions and reaching populations that remain underserved.

Source: Murovska M, Krumina A, Araja D, Kujawski S, Zalewski P, Nora-Krukle Z, Berkis U. Myalgic encephalomyelitis/chronic fatigue syndrome and fibromyalgia – overlap, differences, and emerging insights. J Transl Med. 2026 Feb 20. doi: 10.1186/s12967-026-07889-6. Epub ahead of print. PMID: 41715182. https://link.springer.com/article/10.1186/s12967-026-07889-6 (Full text available as PDF file)

Use of artificial intelligence and machine learning for the management of fibromyalgia: a scoping review

Abstract:

Background: Fibromyalgia (FM) is a complex and multifactorial syndrome characterized by widespread pain, fatigue, cognitive impairment, and other systemic symptoms. The absence of specific biomarkers and the heterogeneous clinical presentation pose significant diagnostic challenges.

Objective: This scoping review aims to explore the current applications of artificial intelligence (AI) and machine learning (ML) in the diagnosis and clinical management of FM.

Methods: A systematic search was conducted in PubMed, EMBASE, and the Cochrane Library using defined keywords related to FM and AI/ML. Studies were included if they addressed ML applications in FM patients. Following PRISMA-ScR guidelines, 43 studies published between 2011 and 2024 were included and analyzed for ML techniques used, diagnostic targets, data types, and clinical relevance.

Results: As expected, the majority of studies done so far focused on improving diagnostic accuracy through supervised algorithms such as support vector machines, neural networks, and ensemble models, as well as unsupervised clustering and dimensionality reduction techniques. Notable findings include the identification of neurophysiological signatures via fMRI, gene expression patterns, retinal imaging changes, and metabolomic biomarkers that distinguish FM patients from controls. For instance, one study investigating circulating microRNAs used a Random Forest model to identify 11 microRNAs (e.g. hsa-miR-28-5p, hsa-miR-29a-3p, hsa-miR-150-5p) capable of differentiating patients with FM, ME/CFS, and healthy controls, suggesting their potential as biomarkers for more accurate diagnoses. Reported model accuracies ranged from 82% to 100%, although most studies were pilot-based with small and imbalanced samples, limiting generalizability.

Conclusion: AI and ML offer promising tools to overcome longstanding limitations in FM diagnosis and treatment. While current findings demonstrate significant potential, larger, multicenter studies with rigorous validation protocols are essential to finally establish these approaches as clinically reliable solutions.

Source: Clempi Almeida E Silva AL, Reis VHPF, Lamoglia ASA, Souza Desidério C, Freire Oliveira CJ. Use of artificial intelligence and machine learning for the management of fibromyalgia: a scoping review. J Man Manip Ther. 2026 Feb 17:1-17. doi: 10.1080/10669817.2026.2630999. Epub ahead of print. PMID: 41700030. https://pubmed.ncbi.nlm.nih.gov/41700030/

Hypermethylation of OPRM1: Deregulation of the Endogenous Opioid Pathway in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Fibromyalgia

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) and fibromyalgia (FM) are debilitating disorders with overlapping symptoms such as chronic pain and fatigue. Dysregulation of the endogenous opioid system, particularly µ-opioid receptor function, may contribute to their pathophysiology. This study examined whether epigenetic modifications, specifically µ-opioid receptor 1 gene (OPRM1) promoter methylation, play a role in this dysfunction.
Using a repeated-measures design, 28 ME/CFS/FM patients and 26 matched healthy controls visited the hospital twice within four days. Assessments included blood sampling for epigenetic analysis, a clinical questionnaire battery, and quantitative sensory testing (QST). Global DNA (hydroxy)methylation was quantified via liquid chromatography–tandem mass spectrometry, and targeted pyrosequencing was performed on promoter regions of OPRM1, COMT, and BDNF. ME/CFS/FM patients reported significantly worse symptom outcomes.
No differences in global (hydroxy)methylation were found. Patients showed significantly higher OPRM1 promoter methylation, which remained after adjusting for symptom severity and QST findings. Across timepoints, OPRM1 methylation consistently correlated with BDNF Promoter I and Exon III methylation. This is, to the best of our knowledge, the first study examining OPRM1 methylation in ME/CFS/FM. Increased OPRM1 methylation in patients, independent of symptoms or pain sensitivity measures, supports the hypothesis of dysregulated opioidergic signaling in these conditions.
Source: Wyns A, Hendrix J, Van Campenhout J, Buntinx Y, Xiong H-Y, De Bruyne E, Godderis L, Nijs J, Rice D, Chiang D, et al. Hypermethylation of OPRM1: Deregulation of the Endogenous Opioid Pathway in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome and Fibromyalgia. International Journal of Molecular Sciences. 2026; 27(2):826. https://doi.org/10.3390/ijms27020826  https://www.mdpi.com/1422-0067/27/2/826 (Full text)

The Gut-Brain-Immune Axis in Environmental Sensitivity Illnesses: Microbiome-Centered Narrative Review of Fibromyalgia Syndrome, Myalgic Encephalomyelitis/Chronic Fatigue Syndrome, and Multiple Chemical Sensitivity

Abstract:

Environmental sensitivity illnesses-including fibromyalgia syndrome (FMS), myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), and multiple chemical sensitivity (MCS)-are chronic, disabling disorders characterized by hypersensitivity to environmental stimuli, persistent fatigue, widespread pain, and neurocognitive and autonomic dysfunction. Although their diagnostic criteria differ, increasing evidence suggests overlapping clinical features and shared biological mechanisms. A unifying hypothesis highlights the gut-brain-immune axis, where alterations in the intestinal microbiome, epithelial barrier dysfunction, and aberrant immune signaling interact with central sensitization and systemic metabolic dysregulation.

Recent studies demonstrate reduced microbial diversity, depletion of anti-inflammatory taxa (e.g., Faecalibacterium prausnitzii, Bifidobacterium), and enrichment of pro-inflammatory Clostridium species across these conditions. These shifts likely alter production of short-chain fatty acids, amino acid metabolites, and complex lipids, with downstream effects on mitochondrial function, neuroinflammation, and host energy metabolism. Moreover, emerging clinical interventions-including probiotics, prebiotics, synbiotics, and fecal microbiota transplantation-suggest a potential role for microbiome-targeted therapies, though controlled evidence remains limited.

This review synthesizes current knowledge on microbiome alterations in FMS, ME/CFS, and MCS, emphasizing their convergence on metabolic and immune pathways. By integrating microbial, immunological, and neurophysiological perspectives, we propose a microbiome-centered framework for understanding environmental sensitivity illnesses and highlight avenues for translational research and therapeutic innovation.

Source: Watai K, Taniguchi M, Azuma K. The Gut-Brain-Immune Axis in Environmental Sensitivity Illnesses: Microbiome-Centered Narrative Review of Fibromyalgia Syndrome, Myalgic Encephalomyelitis/Chronic Fatigue Syndrome, and Multiple Chemical Sensitivity. Int J Mol Sci. 2025 Oct 14;26(20):9997. doi: 10.3390/ijms26209997. PMID: 41155291. https://www.mdpi.com/1422-0067/26/20/9997 (Full text)

The genetic architecture of fibromyalgia across 2.5 million individuals

Abstract:

Fibromyalgia is a common and debilitating chronic pain syndrome of poorly understood etiology. Here, we conduct a multi-ancestry genome-wide association study meta-analysis across 2,563,755 individuals (54,629 cases and 2,509,126 controls) from 11 cohorts, identifying the first 26 risk loci for fibromyalgia.

The strongest association was with a coding variant in HTT , the causal gene for Huntington’s disease. Gene prioritization implicated the HTT regulator GPR52 , as well as diverse genes with neural roles, including CAMKV ,  DCC ,  DRD2 / NCAM1 ,   MDGA2 , and CELF4 . Fibromyalgia heritability was exclusively enriched within brain tissues and neural cell types.

Fibromyalgia showed strong, positive genetic correlation with a wide range of chronic pain, psychiatric, and somatic disorders, including genetic correlations above 0.7 with low back pain, post-traumatic stress disorder and irritable bowel syndrome. Despite large sex differences in fibromyalgia prevalence, the genetic architecture of fibromyalgia was nearly identical between males and females.

This work provides the first robust genetic evidence defining fibromyalgia as a central nervous system disorder, thereby establishing a biological framework for its complex pathophysiology and extensive clinical comorbidities.

Source: Kerrebijn I, Bjornsdottir G, Arbabi K, Urpa L, Haapaniemi H, Thorleifsson G, Stefansdottir L, Frangakis S, Valliere J, Kunorozva L, Abner E, Ji C, Aagaard B, Bliddal H, Brunak S, Bruun MT, Didriksen M, Erikstrup C, Geirsson AJ, Gudbjartsson DF, Hansen TF, Jonsdottir I, Knight S, Knowlton KU, Mikkelsen C, Nadauld LD, Olafsdottir TA, Ostrowski SR, Pedersen OB, Saevarsdottir S, Skuladottir AT, Sørensen E, Stefansson H, Sulem P, Sveinsson OA, Thorlacius GE, Thorsteinsdottir U, Ullum H, Vikingsson A, Werge TM; Chronic Pain Genomics Consortium; FinnGen; DBDS Genomic Consortium; Estonian Biobank Research Team; Genes & Health Research Team; Saxena R, Stefansson K, Brummett CM, Glintborg B, Clauw DJ, Thorgeirsson TE, Williams FM, Sinnott-Armstrong N, Ollila HM, Wainberg M. The genetic architecture of fibromyalgia across 2.5 million individuals. medRxiv [Preprint]. 2025 Sep 19:2025.09.18.25335914. doi: 10.1101/2025.09.18.25335914. PMID: 41001472; PMCID: PMC12458511. https://pmc.ncbi.nlm.nih.gov/articles/PMC12458511/ (Full text available as PDF file)