Tag: thesis

An experimental study investigating the link between symptom reporting and heart rate variability in chronic fatigue syndrome patients

Abstract:

Our Master’s thesis falls within the research domain of Rehabilitation Sciences and Physiotherapy. In our study we investigated patients with chronic fatigue syndrome (CFS).

CFS is a complicated disorder of which the pathology is still poorly understood. Due to the significant prevalence, the socio-economic impact of the disorder is high. In addition to the physiological dysfunctions that are often reported in CFS literature, patients can also experience altered symptom perception. Patients for example show increased subjective responses to unpleasant somatic stimuli in comparison with healthy persons (Van den Houte et al., 2018). Therefore, this study project fits within the domain of pain, fatigue and somatically unexplained physical symptoms.

Despite a lot of articles reporting the role of altered symptom perception, they mainly focused on symptom perception in the lab. However, these laboratory measurements do not take day-to-day variability in symptoms into account.

We think that the lack of studies investigating the symptomatology in CFS patients via ecological momentary measurements is a gap in the literature. Therefore, in our study, we executed symptom assessments in the lab and in daily life.

In addition, we investigated the interactions between the reported symptoms and heart rate variability (HRV) in order to investigate, on a small scale, if psychological and physiological dysfunctions in patients do not work independently.

Extra information about the pathology of CFS is useful to all professionals in rehabilitation sciences and physical therapy who work with CFS patients. It will help professionals to understand the complex problem of CFS better and to tailor the care for these patients.

Our study is situated in a larger study project with the title “Identifying (psycho)physiology-based subgroups in chronic fatigue syndrome and their relevance for rehabilitation” and with study number S66452. The project is reimbursed by Fonds Wetenschappelijk Onderzoek. The project runs in collaboration with the Multidisciplinary Diagnostic Center of UZ Leuven, the Multidisciplinary Expertise Center Tumi Therapeutics, the Vlaams Instituut voor Biotechnologie KU Leuven Raes Lab and IMEC. All laboratory tasks were conducted in the University Hospital of Leuven.

The study is written in line with the central format. The study topics and research questions were determined in collaboration with Msc. Y. Dooms and Dr. Maaike Van Den Houte. Due to the fact that the study was a component of an ongoing research project, we were not involved in decisions about research design or methodology.

We carried out the academic writing procedure concerning this Master’s thesis. During the writing procedure, we received input from Msc. Y. Dooms. The thesis was written in close cooperation amongst both of us. We both independently contributed to the thesis, reviewed it, and wrote multiple sections together. The data-analysis was done in collaboration with Dr. Maaike Van Den Houte.

Source: Jentro Dest and Daan Grosemans.An experimental study investigating the link between symptom reporting and heart rate variability in chronic fatigue syndrome patients. Master Thesis [University of Hasselt] https://documentserver.uhasselt.be/bitstream/1942/41042/1/1b9fa48e-2513-4665-8ba1-a6b1eb7f2056.pdf (Full text)

System and methods to determine ME/CFS & Long Covid disease severity using wearable sensor & survey data

Abstract:

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a debilitating disease with high probability of misdiagnosis and significant unmet medical needs that affects as many as 2.5 million people in the U.S. and causes enormous burden for patients, their caregivers, the healthcare system and society. Between 84 to 91 percent of ME/CFS patients are not yet diagnosed [6, 19], and at least one-quarter of ME/CFS patients are house- or bedbound at some point in their lives [12, 13]. The impact of ME/CFS to the U.S. economy, is about $17 to $24 billion in medical bills and lost income from lost household and labor force productivity per year [7, 13].

Current widely used diagnosis methods of ME/CFS and other diseases with similar clinical symptoms like Long COVID [6, 21] are highly dependent on patients’ self reporting [4, 5] and standardized survey, which are not optimal for medical diagnosis. In a joint study with The Bateman Horne Center (BHC)1, we designed and developed a system prototype that was able to stably collect terabytes of inertial measurement unit (IMU) time-series data, and analyzed multiple candidate parameters derived from them that could be used as reliable biomarkers for ME/CFS and other diseases with similar clinical symptoms.

Utilizing our system prototype, MetaProcessor, we conducted grouped t-tests on data collected from the EndoPAT study group (55 recruited, 51 participated, 30 ME/CFS, 15 Long COVID, 6 healthy control) to evaluate the predictive power of Upright Position Time (UpTime), Hours of Upright Activity (HUA), and Steps/Day. Through statistical analysis, we were able to assert the following for ME/CFS versus healthy control:

1. UpTime yielded a low p-value of 0.00004, indicating a significant difference between the groups and demonstrating its potential as a reliable measure for differentiating ME/CFS from healthy control populations.

2. HUA had a p-value of less than 0.00004, suggesting it could also serve as a useful measure for distinguishing ME/CFS from healthy control groups.

3. Steps/Day, x-axis and y-axis, had p-values of 0.01059 and 0.08665, respectively, indicating that step count may be relevant for differentiating ME/CFS individuals from healthy controls, but step count alone may not be sufficient to reliably distinguish between these groups.

In a linear regression analysis, we found a moderately positive correlation between UpTime and HUA with r 2 = 0.68. Overall, we can confidently conclude that UpTime is a superior overall predictor due to its objective nature and the lowest p-values observed across all groups.

Source: System and methods to determine ME/CFS & Long Covid disease severity using wearable sensor & survey data. Sun, Y. Thesis, Bachelor of Science, The University of Utah. https://ccs.neu.edu/~ysun/publications/system-and-methods-to-determine-mecfs-and-longcovid-disease-severity-using-wearable-sensor-and-survey-data.pdf (Full text)

Investigating Immune Reactivity to the Intestinal Microbiome in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

Introduction: Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) pathogenesis is thought to be multisystemic, including the immune and gastrointestinal systems. A proportion of patients experience gastrointestinal disturbances with evidence suggesting a leaky gut. It was hypothesised that a leaky gut and microbial translocation causes a breach in immune tolerance, promoting inflammation and autoimmunity.

Aims: A) determine whether severe ME/CFS patients have increased systemic and mucosal immunoglobulin (Ig) reactivity to the intestinal microbiome, and B) determine which intestinal microbes serum IgG was directed against.

Methods: Serum and stool samples were collected from five pairs of severe ME/CFS patients and matched household controls. Enzyme linked immunosorbent assays were developed to quantify IgG in serum, bound and non-bound IgA in stool and serum IgG levels reactive with autologous and heterologous stool bacteria. Flow cytometry methods were developed to quantify both stool microbial load and the proportion of stool microbes reactive with mucosal IgA and serum IgG. A ‘bug FACS’ method was developed to identify and quantify serum IgG reactivity to stool bacteria and fungi.

Results: The main finding was that severe ME/CFS patients have significantly lower levels of serum IgG reactive to heterologous stool bacteria compared to their matched household controls. In addition, severe ME/CFS patients do not have higher levels of serum IgG reactive to heterologous stool bacteria than autologous stool bacteria. Severe ME/CFS patients also have a non-significant increase of IgG binding to Campylobacter jejuni and Pseudomonas viridiflava compared to their matched household controls. Analysis of mucosal IgA found ME/CFS patients with a long disease duration had higher microbe bound IgA concentrations compared to their matched household controls.

Conclusion: This thesis presents results from the first ME/CFS study to investigate serum IgG immune reactivity to stool microbes. Findings suggest ME/CFS patients have an impaired serum IgG immune response to the intestinal microbiome.

Source: Seton, Katharine.  Investigating Immune Reactivity to the Intestinal Microbiome in Myalgic Encephalomyelitis/Chronic Fatigue Syndrome.  Doctoral thesis, University of East Anglia. https://ueaeprints.uea.ac.uk/id/eprint/90862/

Investigating the Genetic and Immunological Aetiology of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Abstract:

This thesis describes two investigations into the disease Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS), specifically its genetic aetiology and immune system alterations.

The first study investigated the genetic basis of ME/CFS using Genome-wide Association Studies (GWAS) by attempting to replicate and extend results previously found using UK Biobank cohort data. GWAS attempt to identify associations between DNA variants and phenotypes. T his GWAS was novel, conducted on new phenotypes constructed by combining those in the most up-to-date UK Biobank data release. A new, previously unseen, genome-wide significant association was found on chromosome 6 for males with ME/CFS within the gene PDE10A. Further results were not genome-wide significant, but many were suggestive and hence independent replication may justify further research.

A previous analysis on the UK Biobank cohort had identified an indicative association in females between variants around the SLC25A15 gene at genome-wide significance. I adopted a hypothesis that the dietary protein intake of people with the CFS risk variants would be lower than those with the alternative alleles, due to potentially reduced production of mitochondrial ornithine transporter 1 (ORNT1). However, this association with dietary protein intake was not supported by UK Biobank data.

Additionally, I investigated associations between the human leukocyte antigen (HLA) alleles and the ME/CFS phenotype using UK Biobank data. Associations between alleles within the HLA-C and -DQB1 genes had previously been found in a cohort of Norwegian people with ME/CFS, and my goal was to seek replication of these results in a larger dataset. None of the associations found in the UK Biobank proved to be genome-wide significant.

In my second study I investigated the use of T-cell clonal diversity as a potential biomarker for ME/CFS. This project used cells from CureME Biobank samples in collaboration with Systems Biology Laboratory (SBL). I developed a data analysis pipeline to analyse T-cell receptor (TCR) genomic DNA data based on the best practices currently used in the fields of immunology and mathematical biology. This approach used a mathematical notion of entropy as a measure for the diversity of TCR repertoires, in this way combining all of the most commonly used metrics in mathematical biology. When combined, these measures form a profile for each repertoire, a set of which can be sorted using a machine learning algorithm to partition the repertoires into subgroups.

My hypothesis was that the T-cell clonal expansion of people with ME/CFS would be greater than for healthy controls, and comparable to disease (multiple sclerosis) controls. Although this method was able to effectively classify TCR chains using simulated data, results from experimentally-derived data did not support the hypothesis, with the most effective classifications for both CD4+ and CD8+ cells failing to pass corrections for multiple hypothesis significance testing.

Lay summary

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a disease that affects millions of people around the world. Very little is understood about the cause or progression of the disease, and there is no known cure. At present, there is also no reliable clinical test to determine whether a person has ME/CFS.

This thesis explores the potential for a genetic or immunological basis for ME/CFS, with the goal to eventually find a biomarker that could be used in diagnosis.

The first part of this thesis investigates whether genetic variants are more (or less) common among those with ME/CFS than in the general population. In particular, the region of the genome that encodes immune system proteins was of interest, as previous studies have shown associations between this region and the disease.

Using strict statistical thresholds, none of the previously found associations were replicated. However, one new association was found, with the gene PDE10A, which is implicated in central nervous system diseases, such as Parkinsons and Huntingtons disease. This association has never been seen before, and would require replication in a new cohort before its role in ME/CFS could be confirmed. However, it represents a promising avenue for new research.

The second part of this thesis investigates T-cells. These are highly specialised immune cells in the blood, each of which targets an antigen (foreign substance) such as from a virus. When a T-cell recognises this antigen, it clones itself repeatedly. This clonal expansion is measurable, and can serve as evidence of immune system activation.

My hypothesis was that this immune signature could be used to distinguish people with ME/CFS from healthy controls and others diagnosed with another disease.

I used a mathematical measure of diversity and a machine learning method to sort their immune profiles into groups. However, the pattern of immune activation was not sufficiently clear to provide consistent classification. Hence, the role of the immune system in ME/CFS is still unclear, and the utility of this method as a diagnostic biomarker is not proved.

Source: Joshua James Dibble. Investigating the Genetic and Immunological Aetiology of Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. PhD Thesis [University of Edinburgh]  https://era.ed.ac.uk/bitstream/handle/1842/39763/DibbleJJ_2022.pdf?sequence=1&isAllowed=y (Full text)

Investigating the neural substrates of Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME) : a structural and functional MRI study

Abstract:

Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME) is characterised by continuous fatigue and has many diagnostic criteria. Cognitive dysfunction affects 86-94% of adults with CFS/ME.

This thesis used MRI applications to investigate brain structure and function in CFS/ME. This thesis hypothesised to find brain volume differences, functional connectivity differences in brain networks, and functional differences measured by Blood Oxygenation Level Dependant (BOLD) signal activation during working memory task performance.

The working memory paradigm was designed to investigate working memory components, processing and storage separately and combined. The relationship between fatigue and performance was assessed. This thesis’s original contribution provides evidence that the salience network might have altered resting-state functional connectivity in CFS/ME in the absence of morphological differences.

The salience network is involved in detecting and integrating salient sensory information; therefore, disruption in this network might disrupt incoming cognitive stimuli and influence other networks’ connectivity, involved in fatigue and impaired memory.

In the more demanding task, participants with CFS/ME were slower and less accurate but used the same working memory network as healthy controls. No brain volume differences, nor atrophy were found. The differences between these findings compared to previous studies might be due to different study designs, analysis methods, sample sizes with different symptoms, including illness duration, physical inactivity and sleep disturbance.

The salience network alteration could potentially have a significant role in CFS/ME, as we cannot determine cause and effect with current experimental design the association with fatigue and other CFS/ME symptoms remains unclear. Using longitudinal studies that account for neurologically relevant confounders are needed in CFS/ME to further investigate the role of salience network.

Source: Almutairi, Basim S. Investigating the neural substrates of Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME) : a structural and functional MRI study. PhD Thesis, University of Bristol. uk.bl.ethos.866683  https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.866683

Diagnosis of Chronic Fatigue Syndrome in Adolescents

Abstract

Diagnostic labels such as Chronic Fatigue Syndrome (CFS), Myalgic Encephalomyelitis (ME) and Systemic Exertion Intolerance Disease (SEID) represent different approaches to the enigmatic phenomenon of long-lasting unexplained fatigue.

More than 20 case definitions/diagnostic criteria for CFS/ME/SEID exist. All are based on subjective symptom reports, and the details of symptom requirement vary considerably. No one has been thoroughly validated.

The present thesis shows that adolescent CFS patients fulfilling the Canadian Consensus Criteria (CCC) or SEID-criteria do not differ from adolescent CFS patients diagnosed according to broad diagnostic criteria regarding neuroendocrine, cardiovascular, inflammatory, infectious or cognitive variables.

Furthermore, there appears to be no distinct subgroups within the overarching CFS label, but rather a continuum of subjective symptom experiences and pathophysiological aberrations.

These findings question the descriptive, predictive and construction validity of the CCC and SEID-criteria, and more fundamentally question the rationale of sub-classifying chronically fatigued patients based on clinical symptoms.

Rather, the results seem to suggest that all patients with an unexplained chronic fatigue may be seen as one entity in a qualitative sense, albeit with individual, quantitative differences regarding symptom severity and functional impairments.

Source: Tarjei Tørre Asprusten. Diagnosis of Chronic Fatigue Syndrome in Adolescents. https://www.duo.uio.no/bitstream/handle/10852/92148/PhD-Asprusten-2022.pdf?sequence=1 (Full PhD thesis)

Investigating Access to Specialist Chronic Fatigue Syndrome / Myalgic Encephalomyelitis (CFS/ME) Services for Ethnic Minority Children

Abstract:

Paediatric Chronic Fatigue Syndrome/Myalgic Encephalomyelitis (CFS/ME) is a relatively common, complex and disabling condition. CFS/ME is more common in ethnic minority adults, and is likely to be more common in ethnic minority children, but very few ethnic minority children access specialist CFS/ME services.

The aim of this PhD was to explore both the barriers and facilitators ethnic minority children face in accessing CFS/ME services, with an aim to make access more equal. Different methods were used: 1) systematic review, 2) data analysis, 3) qualitative interviews with young people, parents, community ‘influencers’, healthcare professionals, and 4) focus groups with community members.

I conducted a mapping systematic review to: (1) understand barriers ethnic minority children experience when accessing specialist medical services for chronic or mental healthcare conditions, (2) interventions to improve access. This synthesis describes the most common barrier to be ‘Knowledge’ but ‘Cultural Factors’ and ‘Stigma’ were also important. Interventions that focus on reducing multiple access barriers showed the most promise. This review also highlighted the role of facilitators, which informed the PhD.

Data analysis of the baseline characteristics of children who accessed specialist paediatric CFS/ME services and were recruited into a clinical trial showed only 3.93% of children described themselves as an ethnic minority, however data capture methods suggest ethnicity may not be accurately recorded.

Interviews with 25 participants (3 young people with CFS/ME; 5 family members, 14 community leaders and 3 medical professionals), and focus groups with 23 community participants were conducted and thematic analysis identified multiple barriers to accessing CFS/ME services, with three key barriers (‘Conceptualisation of CFS/ME’; ‘Cultural Factors’; and ‘Going to the Doctors’) and few facilitators. Terminology was also important, with “community leaders” declining the term “leader”.

Participants suggested the following ideas to improve access: 1) knowledge and awareness building initiatives to increase understanding of CFS/ME and reduce stigma and 2) healthcare system improvements, including more General Practitioner (GP) consultations, shorter waiting times, and staff of different ethnicities. Future work is needed to pilot these ideas to improve access and develop interventions.

Source: Catherine Linney Bristol Medical School Student thesis: Doctoral Thesis › Doctor of Philosophy (PhD) https://research-information.bris.ac.uk/en/studentTheses/investigating-access-to-specialist-chronic-fatigue-syndrome-myalg  https://research-information.bris.ac.uk/ws/portalfiles/portal/306612306/REDACTED_Final_Copy_2021_12_02_Linney_C_PhD.pdf (Full text)

Ophthalmic correlates of Myalgic Encephalomyelitis (ME)/Chronic Fatigue Syndrome (CFS)

Abstract:

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) is a chronic, debilitating disorder. With the exception of disabling fatigue, there are few definitive clinical features of the condition. As a consequence, patients often have difficulty gaining an appropriate diagnosis. As such, identifying distinct clinical feature of ME/CFS is an important issue. One under researched area of ME/CFS associated symptoms concerns problems related to vision.

People with ME/CFS consistently report a range of symptoms related to the quality of their vision including pain in the eyes, hypersensitivity to light, difficulty focusing on images, slow eye movements, and difficulty tracking object movement. However, there has been little attempt to verify patients’ self-reports using objective methods. The purpose of the experiments presented in this thesis was to determine the effects of ME/CFS on: (i) performance on a range of tests of visual sensitivity and (ii) the morphology of the retina.

Compared to controls, the ME/CFS group exhibited reduced accommodation, larger pupil diameters, reduced colour discrimination and poorer contrast sensitivity towards lower spatial frequencies. Thinning in the photoreceptor layers of the retina (the Outer Segment & the Outer Nuclear layer) was also apparent. These findings support the claims of people with ME/CFS that they experience problems related to their vision and its function. They also represent a potential marker of ME/CFS that may aid in its diagnosis.

Source: Ahmed, Nadia Sultana. Ophthalmic Correlates of Myalgic Encephalomyelitis (ME)/Chronic Fatigue Syndrome (CFS). Thesis, Univeristy of Leicester, 15-Feb-2018