The Genetics and Epigenetics of Fatigue

Relationship among depression, fatigue, and sleep after traumatic brain injury: The role of physical exercise as a non-pharmacological therapy

Traumatic brain injury (TBI) is a burdensome condition frequently associated with an increased risk of psychiatric disorders. Although the exact molecular signaling pathways have not yet been fully defined, the compromised integrity of functional brain networks in regions such as the prefrontal cortex and anterior cingulate cortex has been linked to persistent symptoms, including depression, fatigue, and sleep disorders. Understanding how TBI affects neural physiology enables the development of effective interventions. One such strategy may be physical exercise, which promotes neural repair and behavioral rehabilitation after TBI. However, there are caveats to consider when interpreting the effects of physical exercise on TBI-induced mental health issues. This review will highlight the main findings from the literature investigating how different physical exercise protocols affect the progression of TBI-induced depression, fatigue, and sleep disturbances. Furthermore, we aim to explore potential neurobiological pathways that explain how physical exercise influences depression, fatigue, and sleep following TBI.

Effects of β-glucans on fatigue: a systematic review and meta-analysis

Several clinical trials suggest that β-glucans may reduce feelings of fatigue, however the results of clinical trials are inconsistent. Additionally, no systematic reviews or meta-analyses have assessed the effects of β-glucans on fatigue. Therefore, this study investigates the effects of β-glucans on fatigue in healthy subjects through a systematic review and meta-analysis. PubMed, Web of Science, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched from database inception to March 15, 2024. The inclusion criterion was a randomized controlled trial (RCT) investigating the effects of β-glucans on healthy subjects' fatigue, vigor, and mood state. To assess risk of bias, we employed the Cochrane risk of bias tool. A random-effects meta-analysis was conducted for the standardized mean difference (SMD). Sixteen RCTs with a total of 1,449 participants were included, and 12 studies provided data suitable for meta-analysis. Meta-analysis revealed that β-glucans significantly reduced feelings of fatigue (SMD = -0.32, 95% CI = -0.53 to -0.12; p = 0.0021), increased vigor (SMD = 0.46, 95% CI = 0.26-0.66; p < 0.0001), and improved mood state (SMD = 0.32, 95% CI = 0.11-0.53; p = 0.0026) compared to the placebo group. The results of the systematic review and meta-analysis indicate that β-glucans may be effective in reducing feelings of fatigue in healthy individuals. However, the number of studies included is insufficient, suggesting that further clinical trials are needed to validate this effect.

Muscle contractile properties and perceived fatigue in the general and diseased population

Knowledge of muscle contractile properties, physical fitness, and their associations with perceived fatigue may provide insights into mechanisms inducing fatigue and treatment targets. We aimed to identify differences in contractile properties and physical fitness between populations, and examine associations with perceived fatigue. We pooled data on perceived fatigue, physical fitness, and contractile properties from six studies, including a control group (n = 90), cancer survivors (n = 27), patients with chronic obstructive pulmonary disease (COPD; n = 16), chronic myeloid leukemia (CML; n = 20), and statin users (n = 64). We evaluated differences between populations, and associations of contractile properties and physical fitness with perceived fatigue. Compared with the control group, we found differences in contractile properties of patients with COPD (larger muscle force decline: β = -10.5%, 95% CI = -16.7; -4.2, increase in early relaxation time (Rt): β = 84.4%, 95% CI = 51.7; 117.0, increase in half Rt: β = 83.1%, 95% CI = 45.5; 120.7, muscle force rise (MFR): β = 0.2%/ms, 95% CI = 0.1; 0.3, and decrease in MFR: β = -24.3%, 95% CI = -35.7; -13.0) and statin users (early Rt: β = -5.4 ms, 95% CI = -10.0; -0.8, increase in early Rt: β = 19.8%, 95% CI = 2.5; 37.1). Associations between contractile properties and perceived fatigue varied across populations. Longer relaxation times were associated with higher perceived fatigue in hemato-oncological populations. To conclude, contractile properties were impaired in patients with COPD and statin users. Associations between contractile properties and perceived fatigue varied across populations. In hemato-oncological populations, impaired muscle relaxation was associated with higher perceived fatigue.

The effect of web-designed education on medication adherence, asthma control and fatigue in patients with asthma: A randomized controlled trial

AIMS

This study aimed to determine the effect of web-designed education developed for asthma patients on drug adherence, asthma control and fatigue.

METHODS

This randomized controlled trial was conducted between August 2021 and January 2022 with 200 individuals suffering from poor asthma control who participated in web-designed education. After the intervention, the asthma patients were followed up for 6 weeks to measure Medication Adherence Report Scale (MARS), Chronic Obstructive Pulmonary Disease and Asthma Fatigue Scale (CAFS), Asthma Control Test (ACT) and Inhalation Devices Usage Techniques Knowledge Test (IDUSTKT). Data were analysed in the Statistical Package for the Social Sciences program using the Chi-square test, Independent t-test, Man-Whitney U test, Wilcoxon test, Paired t-test, Greenhouse-Geisser (F) test and Linear regression.

RESULTS

The web-designed education had a statistically significant effect on the total scores of CAFS, ACT and IDUSTKT for individuals with asthma (p < 0.001). This intervention decreased fatigue levels, improved asthma control and enhanced knowledge of inhalation device usage techniques. Although there was an improvement in medication adherence, this difference was not statistically significant.

CONCLUSION

These results suggest that web-based educational programs can be an effective tool in asthma management and may improve patients' quality of life. Future research should examine the long-term effects of such educational programs and their effectiveness across different demographic groups in more detail.

[Fatigue in the general population: results of the "German Health Update 2023" study]

BACKGROUND

Fatigue is an unspecific symptom complex characterized by tiredness, lack of energy, and lack of concentration and is of considerable public health relevance, due to its links with incapacity for work, risk of accidents, and increased need for healthcare.

METHODS

The analyses are based on data from 9766 adults of the telephone survey "Gesundheit in Deutschland aktuell (GEDA)" 2023. Fatigue was recorded using the Fatigue Assessment Scale (FAS), a validated instrument with 10 questions for self-assessment of fatigue. The scale was dichotomized into yes (at least mild to moderate fatigue) versus no (no fatigue). Population-weighted prevalences of fatigue and associated sociodemographic and health-related factors were calculated in descriptive analyses and multivariable Poisson regression.

RESULTS

The overall prevalence of fatigue in adults in Germany is 29.7% (95% CI 28.1-31.2), is highest in 18- to 29-year-olds (39.6% (95% CI 35.0-44.4)), and decreases in the age groups up to 65-79 years (20.6% (95% CI 18.2-23.3)). It is higher again in the very old age group (33.2% (95% CI 28.9-37.7)). Women have a higher risk of fatigue than men (aRR 1.19 (95% CI 1.08-1.32)). Fatigue is significantly associated with age, lower education, chronic illness, depression, and long COVID, regardless of covariates.

DISCUSSION

GEDA 2023 is one of the few population-based studies to have collected data on fatigue. The results allow estimates to be made for Germany on the frequency of fatigue and the significance of physical, psychological, and social influencing factors. They can be used as a reference or as a basis for trends over time as part of continuous health monitoring in Germany.

Effect of Hearing Intervention Versus Health Education Control on Fatigue: A Secondary Analysis of the ACHIEVE Study

BACKGROUND

Fatigue is a common complaint among older adults with hearing loss. The impact of addressing hearing loss on fatigue symptoms has not been studied in a randomized controlled trial. In a secondary analysis of the Aging and Cognitive Health Evaluation in Elders (ACHIEVE) study, we investigated the effect of hearing intervention versus health education control on 3-year change in fatigue in community-dwelling older adults with hearing loss.

METHODS

Participants aged 70-84 years old with untreated hearing loss recruited across 4 study sites in the United States (Forsyth County, North Carolina; Jackson, Mississippi; Minneapolis, Minnesota; Washington County, Maryland) were randomized (1:1) to hearing intervention or health education control and followed for 3 years. Three-year change in fatigue symptoms was measured by 2 instruments (RAND-36 and PROMIS). We estimated the intervention effect as the difference in the 3-year change in fatigue between intervention and control groups using a linear mixed-effects model under the intention-to-treat principle.

RESULTS

Participants (n = 977) had a mean age (SD) of 76.8 (4.0) years, were 53.5% female and 87.8% White. Over 3 years, a beneficial effect of the hearing intervention versus health education control on fatigue was observed using the RAND-fatigue score (β = -0.12 [95% CI: -0.22, -0.02]). Estimates also suggested beneficial effect of hearing intervention on fatigue when measured by the PROMIS-fatigue score (β = -0.32 [95% CI: -1.15, 0.51]).

CONCLUSIONS

Our findings suggest that hearing intervention may reduce fatigue over 3 years among older adults with hearing loss.

Comparative study for fatigue prevalence in subjects with diseases: a systematic review and meta-analysis

Fatigue is one of the common symptoms in individuals with diseases or disorders, significantly affecting quality of life (QoL) and the prognosis of diseases. This study aimed to comprehensively compare the features of fatigue across a wide range of diseases. We systematically searched the PubMed and Cochrane Library databases from inception to March 31st, 2021, and conducted a meta-analysis to generate precise estimates. The analyses were stratified by classification of diseases, gender, and severity of fatigue (moderate and severe), and study quality was assessed using the Newcastle-Ottawa Scale (NOS). In total, 214 articles (233 prevalence data) met our eligibility criteria, covering 102,024 participants (mean 438 ± 1,421) across 88 diseases. Among these, seventy-eight data sets (52,082 participants) and thirty-nine data sets (10,389 participants) reported gender- and severity-related fatigue prevalence. The overall prevalence among subjects with 88 diseases was 49.4% [95% CI 46.9-52.1]. According to the International Classification of Diseases-10 (ICD-10) classification, the highest prevalence of fatigue (65.9% [95% CI 54.9-79.6]) was observed in patients with mental/behavioral diseases, whereas the lowest prevalence (34.7% [95% CI 24.5-49.2]) was found among those with circulatory system diseases. A slight female dominance (43.5% vs. 49.8%) was observed in the total data, with the most notable female predominance (1.8-fold) seen in patients with low back pain. The top disease groups with a moderate to severe level of fatigue included gastroparesis (92.3%), pulmonary hypertension (90.0%), chronic obstructive pulmonary disease (COPD, 83.2%), and multiple sclerosis (80.0%). These results are the first to comprehensively show the comparative features of fatigue prevalence among subjects across 88 diseases. Our findings provide valuable reference data for future research on fatigue and for the management of patients with fatigue.Prospero registration number: CRD42021270494.

The demographic features of fatigue in the general population worldwide: a systematic review and meta-analysis

BACKGROUND

Fatigue is one of the most common subjective symptoms that impairs daily life and predict health-related events. This study aimed to estimate the prevalence of fatigue in the global population.

METHODS

PubMed and the Cochrane Library were used to search for relevant articles from inception to December 31, 2021. Studies with prevalence data of fatigue in the general population were selected and reviewed by three authors independently and cross-checked. Regarding subgroups, adults (≥18 years), minors (<18 years), and specific occupation population (participants in each study being limited to a specific occupational group), and fatigue types and severity, meta-analysis was conducted to produce point estimates and 95% confidence intervals (95% CI).

RESULTS

From the initial 3,432 studies, 91 studies accounting for 115 prevalence data points (623,624 participants) were finally selected. The prevalence of general fatigue (fatigue lasting < 6 months, or fatigue of unspecified duration) was 20.4% (95% CI, 16.7-25.0) in adults, 11.7% (95% CI, 5.2-26.6) in minors, and 42.3% (95% CI, 33.0-54.2) in specific occupations. Chronic fatigue (fatigue lasting more than 6 months) affected 10.1% (95% CI, 8.2-12.5) of adults, 1.5% (95% CI, 0.5-4.7) of minors, and 5.5% (95% CI, 1.4-21.6) of subjects in specific occupations. There was an overall female-predominant prevalence for all subgroup analyses, with a total odds ratio of 1.4 (95% CI, 1.3-1.6). Regarding the severity and presence of medical causes, the total prevalence of moderate fatigue [14.6% (95% CI, 9.8-21.8)] was 2.4-fold that of severe fatigue [6.1% (95% CI, 3.4-11.0)], while unexplained fatigue (fatigue experienced by individuals without any underlying medical condition that can explain the fatigue) was ~2.7-fold that of explained fatigue (fatigue experienced by individuals with a medical condition that can explain the fatigue); as proportion of 40.0% of physical, 8.6% of mental, and 28.4% of mixed cause.

CONCLUSIONS

This study has produced the first comprehensive picture of global fatigue prevalence in the general population, which will provide vital reference data contributing to fatigue-related research, including the prevention of diseases.

SYSTEMATIC REVIEW REGISTRATION

Identifier: CRD42021270498.

Fatigue in Patients with Idiopathic/Isolated REM Sleep Behavior Disorder

Introduction: Fatigue is one of the most common and disabling symptoms of Parkinson’s Disease (PD). The occurrence and clinical features of fatigue in patients with prodromal PD remain largely elusive. This study aimed to investigate the prevalence and clinical characteristics of fatigue in patients with idiopathic/isolated REM sleep behavior disorders (iRBD). Methods: A total of 97 polysomnography-confirmed iRBD patients were enrolled in this study. A comprehensive neurological assessment (including motor and non-motor assessment) was performed. Fatigue was assessed using the Fatigue Severity Scale (FSS). Motor and non-motor characteristics were compared between iRBD patients with and without fatigue. Logistic regression was used to identify the factors associated with fatigue. Results: The prevalence of fatigue was 35.05%. Compared to the non-fatigue patients, patients with fatigue had higher non-motor symptom scale (NMSS) score (p = 0.009), higher Hamilton Depression Rating Scale (HAMD) score (p = 0.002), and a higher prevalence of orthostatic hypotension (p = 0.021). Multivariate regression analysis showed that depression (OR 4.17, 95% CI 1.13−15.49, p = 0.033) and orthostatic hypotension (OR 2.80, 95% CI 1.09−7.18, p = 0.032) were significantly associated with fatigue in iRBD patients. Additionally, both NMSS (rs = 0.310, p = 0.002) and HAMD (rs = 0.385, p < 0.001) scores were mildly correlated with fatigue severity. Conclusion: Our study showed that fatigue is common in patients with iRBD. In addition, depression and orthostatic hypotension were independently associated with fatigue in iRBD patients.

Genetic Variants of the BAFF Gene and Risk of Fatigue Among Patients With Primary Sjögren's Syndrome

Background/Purpose

Primary Sjögren's Syndrome (SS) is characterized by B lymphocyte hyperactivity with B cell activating factor (BAFF) acting as an important regulator. Single Nucleotide Polymorphisms (SNPs) of the BAFF gene have been implicated in the pathogenesis of several autoimmune diseases characterized by heightened fatigue levels, including primary SS. We aimed to explore potential associations between BAFF SNPs and fatigue status of primary SS patients.

Methods

Fatigue status was assessed in 199 consecutive primary SS patients (Greek cohort) using the Functional Assessment of Chronic Illness Therapy-Fatigue (FACIT-F) scale. Clinical, histological, laboratory, psychometric and personality data were also collected. DNA extracted from peripheral blood of all patients underwent evaluation for the presence of five BAFF SNPs (rs9514827, rs1041569, rs9514828, rs1224141, rs12583006) by PCR. To confirm our findings, an independent replicative cohort of 62 primary SS patients (Dutch cohort) was implemented. Finally, 52 multiple sclerosis (MS) patients were served as disease controls (MS cohort). Analysis of BAFF SNPs in association with fatigue levels was performed by the online platforms SNPStats and SHEsis and the SPSS 26 and Graph Pad Prism 8.00 software.

Results

TT genotype of the rs9514828 BAFF polymorphism was significantly less frequent in the fatigued primary SS patients of the Greek cohort compared to the non-fatigued (14.1% vs 33.3%). The corresponding ORs [95%CI] in the dominant and overdominant models were 0.33 [0.15-0.72], p=0.003 and 0.42 [0.23-0.78], p=0.005 respectively. The association remained significant after adjustment for the variables contributing to fatigue in the univariate analysis (OR [95% CI]: 0.3 [0.1-0.9], p=0.026). Accordingly, in the Dutch cohort, there was a trend of lower mental fatigue among patients carrying the TT rs9514828 BAFF genotype compared to their CC counterparts (4.1 ± 2.4 vs 6.0 ± 2.2 respectively, p=0.06). The rs9514828 BAFF SNP was not significantly associated with fatigue in the MS cohort.

Conclusions

We report a novel association between genetic makeup and primary SS-associated fatigue with the rs9514828 TT genotype decreasing the likelihood of fatigue development among these patients. These findings need validation in multi-center studies.

Fatigue in patients with early rheumatoid arthritis undergoing treat-to-target therapy: predictors and response to treatment

OBJECTIVES

Fatigue is a frequent symptom in rheumatoid arthritis (RA) and has high impact on quality of life. We explored associations between disease activity and fatigue in patients with early RA during the initial 24 months of modern treat-to-target therapy and predictors of fatigue after 24 months of follow-up.

METHODS

Data were obtained from the treat-to-target, tight control Aiming for Remission in Rheumatoid Arthritis: a Randomised Trial Examining the Benefit of Ultrasound in a Clinical Tight Control Regime (ARCTIC) trial. Fatigue was measured on a visual analogue scale (VAS) from 0 to 100 mm and defined as clinically relevant if VAS was ≥20 mm. Baseline predictors of fatigue at 24 months were analysed by multivariable logistic regression.

RESULTS

205 patients with fatigue data at baseline and 24 months were included. Median (25th, 75th percentiles) symptom duration was 5.4 months (2.8, 10.4), fatigue VAS 37.0 mm (13.0, 62.0) and mean Disease Activity Score (DAS) 3.4 (SD 1.1) at baseline. Prevalence of fatigue declined from 69% at baseline to 38% at 24 months. Fewer swollen joints (OR 0.92, 95% CI 0.87 to 0.98, p=0.006), lower power Doppler ultrasound score (OR 0.95, 95% CI 0.90 to 0.99, p=0.027) and higher patient global assessment (PGA) (OR 1.03, 95% CI 1.01 to 1.04, p<0.001) increased the risk of clinically relevant fatigue at 24 months. Not achieving remission at 6 months was associated with a higher risk of reporting fatigue at 24 months.

CONCLUSIONS

Fatigue in patients with early RA was prevalent at disease onset, with a rapid and sustained reduction during treatment. Low objective disease activity and high PGA at baseline were predictors of clinically relevant fatigue at 24 months.

Genetic variants at the RTP4/MASP1 locus are associated with fatigue in Scandinavian patients with primary Sjögren's syndrome

OBJECTIVES

Fatigue is common and severe in primary Sjögren's syndrome (pSS). The aim of this study was to identify genetic determinants of fatigue in pSS through a genome-wide association study.

METHODS

Patients with pSS from Norway, Sweden, UK and USA with fatigue and genotype data available were included. After genotype imputation and quality control, 682 patients and 4 966 157 genetic markers were available. Association analysis in each cohort using linear regression with fatigue as a continuous variable and meta-analyses between the cohorts were performed.

RESULTS

Meta-analysis of the Norwegian and Swedish cohorts identified five polymorphisms within the same linkage disequilibrium block at the receptor transporter protein 4 (RTP4)/MASP1 locus associated with fatigue with genome-wide significance (GWS) (p<5×10-8). Patients homozygous for the major allele scored 25 mm higher on the fatigue Visual Analogue Scale than patients homozygous for the minor allele. There were no variants associated with fatigue with GWS in meta-analyses of the US/UK cohorts, or all four cohorts. RTP4 expression in pSS B cells was upregulated and positively correlated with the type I interferon score. Expression quantitative trait loci effects in whole blood for fatigue-associated variants at RTP4/MASP1 and levels of RTP4 and MASP1 expression were identified.

CONCLUSION

Genetic variations at RTP4/MASP1 are associated with fatigue in Scandinavian pSS patients. RTP4 encodes a Golgi chaperone that influences opioid pain receptor function and MASP1 is involved in complement activation. These results add evidence for genetic influence over fatigue in pSS.

Dietary and herbal supplements for fatigue: A quality assessment of online consumer health information

Background

The Internet is increasingly utilized by patients to acquire information about dietary and herbal supplements (DHSs). Previously published studies assessing the quality of websites providing consumer health information about DHSs have been found to contain inaccuracies and misinformation that may compromise patient safety.. The present study assessed the quality of online DHSs consumer health information for fatigue.

Methods

Six unique search terms were searched on Google, each relating to fatigue and DHSs, across four countries. Across 480 websites identified, 48 were deemed eligible and were quality assessed using the DISCERN instrument, a standardized index of the quality of consumer health information.

Results

Across 48 eligible websites, the mean summed score was 47.64 (SD = 10.38) and the mean overall rating was 3.06 (SD = 0.90). Commercial sites were the most numerous in quantity, but contained information of the poorest quality. In general, websites lacked discussion surrounding uncertainty of information, describing what would happen if no treatment was used, and how treatment choices affect overall quality of life.

Conclusion

Physicians and other healthcare professionals should be aware of the high variability in the quality of online information regarding the use of DHSs for fatigue and facilitate open communication with patients to guide them towards reliable online sources.

Fatigue: A forgotten symptom of asthma

OBJECTIVE

Fatigue is a common symptom frequently reported in many disorders but little is known about the prevalence of fatigue in asthma. The objective of this study was to determine the prevalence of fatigue in asthmatic patients, the effect of fatigue on asthma quality of life and the relationship between fatigue and anxiety/depression MATERIALS AND METHODS: This prospective cross-sectional study was conducted in Uludağ University Faculty of Medicine, Department of Immunology and Allergic Diseases outpatient clinic from June 2019 to December 2019. Fatigue was assessed using the Checklist Individual Strength-Fatigue (CIS-Fatigue), psychological distress was assessed using the Beck Depression Inventory (BDI) and the Beck Anxiety Inventory (BAI) and quality of life were assessed using the Asthma Quality of Life Questionnaire (AQLQ).

RESULTS

In the present study, a total of 168 patients are included with an average age of 43.8 ± 4.3 years. Nearly 64.8% of patients had controlled asthma and (35.2%) patients had uncontrolled asthma. Fatigue (CIS-Fatigue ≥ 27 points) was detected in 62.6% of patients and associated with asthma-related quality of life, asthma control, dyspnea, depression and anxiety (P < 0.05). However, the degree of lung function impairment and asthma severity were not associated with fatigue.

CONCLUSIONS

Fatigue as a symptom is common in asthmatic patients and correlates with asthma-related quality of life, asthma control, dyspnea, depression and anxiety. Future studies are needed to better understand the physical, psychological, behavioural and systemic factors that precipitate or perpetuate fatigue in asthma.

The severity of the pathogen-induced acute sickness response is affected by polymorphisms in genes of the NLRP3 inflammasome pathway

The acute sickness response (ASR) is a stereotyped set of symptoms including fatigue, pain, and disturbed mood, which are present in most acute infections. The immunological mechanisms of the ASR are conserved, with variations in severity determined partly by the pathogen, but also by polymorphisms in host genes. The ASR was characterised in three different serologically-confirmed acute infections in Caucasians (n = 484) across four symptom domains or endophenotypes (termed 'Fatigue', 'Musculoskeletal pain', 'Mood disturbance', and 'Acute sickness'). Correlations were sought with functional single nucleotide polymorphisms in the NLRP3 inflammasone pathway and severity of the endophenotypes. Individuals with severe Fatigue, Musculoskeletal pain, or Mood endophenotypes were more likely to have prior episodes of significant fatigue (11.4 vs. 3.8%, p = 0.07), pain (14.3 vs. 1.2%, p = 0.001), or Mood disturbance (13 vs 1%, p=0.001), suggesting trait characteristics. The high functioning allele of the rs35829419 SNP in NLRP3 was more common in those with severe Fatigue (OR = 13.3, 95% CI: 1.7-104), particularly in a dominant inheritance pattern (OR = 13.4, 95% CI: 1.8-586.3). In a multivariable analysis assuming dominant inheritance, both rs35829419 and the rs4848306 SNP in Interleukin(IL)-1β, were independently associated with severe Fatigue (OR = 29.6, 95% CI: 2.6-330.9 and OR = 13, 95% CI: 2.7-61.8, respectively). The severity of fatigue in acute infection is influenced by genetic polymorphisms in NLRP3 and IL-1β.

Prediction of evening fatigue severity in outpatients receiving chemotherapy: less may be more

Background

Fatigue is the most common and debilitating symptom experienced by oncology patients undergoing chemotherapy. Little is known about patient characteristics that predict changes in fatigue severity over time.

Purpose

To predict the severity of evening fatigue in the week following the administration of chemotherapy using machine learning approaches.

Methods

Outpatients with breast, gastrointestinal, gynecological, or lung cancer (N=1217) completed questionnaires one week prior to and one week following administration of chemotherapy. Evening fatigue was measured with the Lee Fatigue Scale (LFS). Separate prediction models for evening fatigue severity were created using clinical, symptom, and psychosocial adjustment characteristics and either evening fatigue scores or individual fatigue item scores. Prediction models were created using two regression and three machine learning approaches.

Results

Random forest (RF) models provided the best fit across all models. For the RF model using individual LFS item scores, two of the 13 individual LFS items (i.e., "worn out", "exhausted") were the strongest predictors.

Conclusion

This study is the first to use machine learning techniques to predict evening fatigue severity in the week following chemotherapy from fatigue scores obtained in the week prior to chemotherapy. Our findings suggest that the language used to assess clinical fatigue in oncology patients is important and that two simple questions may be used to predict evening fatigue severity.

Pharmaco-fMRI in Patients With Traumatic Brain Injury: A Randomized Controlled Trial With the Monoaminergic Stabilizer (-)-OSU6162

OBJECTIVE

To examine the effects of monoaminergic stabilizer (-)-OSU6162 on brain activity, as measured by blood-oxygen-level-dependent (BOLD) functional magnetic resonance imaging (fMRI), in patients in the chronic phase of traumatic brain injury suffering from fatigue.

SETTING

Neurorehabilitation clinic.

PARTICIPANTS

Patients with traumatic brain injury received either placebo (n = 24) or active treatment (n = 28). Healthy controls (n = 27) went through fMRI examination at one point and were used in sensitivity analysis on normalization of BOLD response.

DESIGN

Randomized, double-blinded, placebo-controlled design.

MAIN MEASURES

Effects on BOLD signal changes from before to after treatment during performance of a fatiguing attention task.

RESULTS

The fMRI results revealed treatment effects within the right occipitotemporal cortex and the right orbitofrontal cortex. In these regions, the BOLD response was normalized relative to healthy controls at the postintervention fMRI session. No effects were seen in regions in which we previously observed activity differences between patients and healthy controls while performing this fMRI task, such as the striatum.

CONCLUSION

(-)-OSU6162 treatment had influences on functional brain activity, although the normalized regional BOLD response was observed in regions that were not a priori hypothesized to be sensitive to this particular treatment, and was not accompanied by any effects on in-scanner test performance or on fatigue.

Fatigue in adults with spinal muscular atrophy under treatment with nusinersen

5q-Associated spinal muscular atrophy is a hereditary neuromuscular disease leading to progressive muscle weakness in which fatigue occurs and affects quality of life. Treatment with the antisense oligonucleotide nusinersen has been shown to improve motor function. Fatigue can be measured within the Fatigue Severity Scale (FSS). FSS is a self-reported questionnaire consisting of nine items to quantify fatigue severity within the last week. Higher values indicating a higher severity. Using the FSS, fatigue was measured in 28 adult patients, subdivided into ambulatory and non-ambulatory, suffering from a genetically confirmed 5q-SMA under treatment with nusinersen in accordance with the label. Correlations were performed among FSS and motor scales, 6-minute walk test (6MWT) and Hammersmiths Functional Motor Scale Expanded (HFMSE). Evaluation was performed prior to treatment initiation and after 6 and 10 months. The mean FSS score for all 28 patients at baseline was 4.61 ± 1.44. After 6 months mean FSS score significantly reduced to 3.92 ± 1.35. After 10 months mean FSS score had not differed from baseline, 3.84 ± 1.25. A moderate negative correlation of the difference of FSS and 6MWT after 6 months compared to baseline conditions was measured. Nusinersen reduces fatigue as measured by the FSS in adult patients with 5q-SMA transiently after initiation of treatment. There was no reduction of FSS 10 months after the beginning of treatment when compared to baseline.

Severe Fatigue is Highly Prevalent in Patients with IPF or Sarcoidosis

In patients with interstitial lung disease (ILD) next to dyspnea, fatigue is expected to be the most prevalent symptom. Surprisingly, the prevalence of severe fatigue has been scarcely studied in ILD patients and limited information on its associated factors is available. This study aimed to determine the prevalence of severe fatigue in patients with idiopathic pulmonary fibrosis (IPF) or pulmonary sarcoidosis and to identify the relationship between fatigue, patient characteristics, and clinical parameters. In this cross-sectional study, fatigue (checklist individual strength-fatigue (CIS-Fat)), demographics, lung function, dyspnea (modified-Medical Research Council (mMRC)), sleepiness (Epworth Sleepiness Scale), anxiety/depression (hospital anxiety and depression scale (HADS-A/HADS-D)), catastrophizing (fatigue catastrophizing scale (FCS)), functional activity impairment (respiratory illness quality-of-life (QoL-RIQ-Activity)), and health status (EuroQol five-dimensional descriptive system (EQ-5D-5L)) were assessed in outpatients with ILD. Mean CIS-Fat scores were 34.1 (SD ± 11.2) in 59 IPF patients and 40.0 (12.3) in 58 sarcoidosis patients. Severe fatigue (SD ± ≥36 points) was present in IPF patients (47.5%) and sarcoidosis (69%). In IPF, CIS-Fat correlated strongly (ρ > 0.5; p < 0.01) with FCS, QoL-RIQ-Activity, and EQ-5D-5L-Health and moderately (0.3 < ρ < 0.5; p < 0.01) with EQ-5D-5L-Index, mMRC, and HADS-D. In sarcoidosis, CIS-Fat correlated strongly with EQ-5D-5L-Health, QoL-RIQ-Activity, EQ-5D-5L-Index, HADS-D, and mMRC and moderately with FCS and hospitalization <12 months. Severe fatigue is highly prevalent in ILD patients and is associated with dyspnea, depression, catastrophizing, functional activity impairments, and QoL.

A novel mutation in Slc2a4 as a mouse model of fatigue

Chronic fatigue is a debilitating disorder with widespread consequences, but effective treatment strategies are lacking. Novel genetic mouse models of fatigue may prove invaluable for studying its underlying physiological mechanisms and for testing treatments and interventions. In a screen of voluntary wheel-running behavior in N-ethyl-N-nitrosourea mutagenized C57BL/6J mice, we discovered two lines with low body weights and aberrant wheel-running patterns suggestive of a fatigue phenotype. Affected progeny from these lines had lower daily activity levels and exhibited low amplitude circadian rhythm alterations. Their aberrant behavior was characterized by frequent interruptions and periods of inactivity throughout the dark phase of the light-dark cycle and increased levels of activity during the rest or light phase. Expression of the behavioral phenotypes in offspring of strategic crosses was consistent with a recessive inheritance pattern. Mapping of phenotypic abnormalities showed linkage with a single locus on chromosome 1, and whole exome sequencing identified a single point mutation in the Slc2a4 gene encoding the GLUT4 insulin-responsive glucose transporter. The single nucleotide change (A-T, which we named "twiggy") was in the distal end of exon 10 and resulted in a premature stop (Y440*). Additional metabolic phenotyping confirmed that these mice recapitulate phenotypes found in GLUT4 knockout mice. However, to the best of our knowledge, this is the first time a mutation in this gene has been shown to result in extensive changes in general behavioral patterns. These findings suggest that GLUT4 may be involved in circadian behavioral abnormalities and could provide insights into fatigue in humans.

A Pilot Study Using a Multistaged Integrated Analysis of Gene Expression and Methylation to Evaluate Mechanisms for Evening Fatigue in Women Who Received Chemotherapy for Breast Cancer

CONTEXT

Fatigue is the most common symptom associated with cancer and its treatment. Investigation of molecular mechanisms associated with fatigue may identify new therapeutic targets.

OBJECTIVE

The objective of this pilot study was to evaluate the relationships between gene expression and methylation status and evening fatigue severity in women with breast cancer who received chemotherapy.

METHODS

Latent class analysis (LCA) was used to identify evening fatigue phenotypes. In this analysis, the lowest (i.e., moderate, n = 7) and highest (i.e., very high, n = 29) fatigue-severity classes identified using LCA were analyzed via two stages. First, a total of 32,609 transcripts from whole blood were evaluated for differences in expression levels between the classes. Next, 637 methylation sites located within the putative transcription factor binding sites for those genes demonstrating differential expression were evaluated for differential methylation state between the classes.

RESULTS

A total of 89 transcripts in 75 unique genes were differentially expressed between the moderate (the lowest fatigue-severity class identified) and very high evening fatigue classes. In addition, 23 differentially methylated probes and three differentially methylated regions were found between the moderate and very high evening fatigue classes.

CONCLUSIONS

Using a multistaged integrated analysis of gene expression and methylation, differential methylation was identified in the regulatory regions of genes associated with previously hypothesized mechanisms for fatigue, including inflammation, immune function, neurotransmission, circadian rhythm, skeletal muscle energy, carbohydrate metabolism, and renal function as well as core biological processes including gene transcription and the cell-cycle regulation.

Association of Fatigue With TPH2 Genetic Polymorphisms in Women With Irritable Bowel Syndrome

Fatigue is the most common extraintestinal symptom in women with irritable bowel syndrome (IBS). Genetic polymorphisms of monoamines are associated with fatigue in many chronic diseases. In this pilot exploratory study, the primary aim was to determine whether genetic polymorphisms of tryptophan hydroxylase ( TPH1/TPH2), serotonin reuptake transporter ( SERT), or catechol-O-methyltransferase ( COMT) are associated with fatigue in women with IBS. Additionally, analysis explored whether these genetic associations with fatigue would be present when controlling for abdominal pain, psychological distress, feeling stressed, and sleepiness during the day. Secondary analysis of two randomized controlled trial baseline data sets in Caucasian women with IBS ( N = 185) was conducted. Participants kept a daily diary with one dimension (i.e., severity) for each of the 26 symptoms, including fatigue, for 28 days prior to randomization. DNA samples were tested for single-nucleotide polymorphisms (SNPs) of TPH1 (four SNPs) /TPH2 (one SNP), SERT (one SNP), and COMT (one SNP). Analysis of covariance was used to examine associations of percentage of diary days with moderate to very severe symptoms with genetic polymorphisms. Only one SNP, TPH2 rs4570625, was significantly associated with fatigue ( p = .005). T-allele (low functional) carriers of TPH2 (i.e., G/T or T/T genotypes) reported a greater percentage of days with moderate to very severe fatigue than G/G homozygotes ( p = .001). Reduced synthesis of tryptophan in the central nervous system may contribute to reports of fatigue in women with IBS. Understanding genetic risk factors for fatigue may elucidate preemptive strategies to reduce fatigue in individuals with IBS.

Fatigue is Highly Prevalent in Patients with Asthma and Contributes to the Burden of Disease

The 2018 update of the Global Strategy for Asthma Management and Prevention does not mention fatigue-related symptoms. Nevertheless, patients with asthma frequently report tiredness, lack of energy, and daytime sleepiness. Quantitative research regarding the prevalence of fatigue in asthmatic patients is lacking. This retrospective cross-sectional study of outpatients with asthma upon referral to a chest physician assessed fatigue (Checklist Individual Strength-Fatigue (CIS-Fatigue)), lung function (spirometry), asthma control (Asthma Control Questionnaire (ACQ)), dyspnea (Medical Research Council (MRC) scale), exercise capacity (six-minute walk test (6MWT)), and asthma-related Quality-of-Life (QoL), Asthma Quality of Life Questionnaire (AQLQ) during a comprehensive health-status assessment. In total, 733 asthmatic patients were eligible and analyzed (47.4 ± 16.3 years, 41.1% male). Severe fatigue (CIS-Fatigue ≥ 36 points) was detected in 62.6% of patients. Fatigue was not related to airflow limitation (FEV1, ρ = -0.083); was related moderately to ACQ (ρ = 0.455), AQLQ (ρ = -0.554), and MRC (ρ = 0.435; all p-values < 0.001); and was related weakly to 6MWT (ρ = -0.243, p < 0.001). In stepwise multiple regression analysis, 28.9% of variance in fatigue was explained by ACQ (21.0%), MRC (6.5%), and age (1.4%). As for AQLQ, 42.2% of variance was explained by fatigue (29.8%), MRC (8.6%), exacerbation rate (2.6%), and age (1.2%). Severe fatigue is highly prevalent in asthmatic patients; it is an important determinant of disease-specific QoL and a crucial yet ignored patient-related outcome in patients with asthma.

Low body mass index and efavirenz use are independently associated with self-reported fatigue in HIV-infected patients

This retrospective cohort study was conducted from January 2009 to July 2016 to explore the occurrence and risk factors of self-reported fatigue within the first 6 months after receiving antiretroviral treatment (ART) among patients living with HIV in Taizhou City of Zhejiang province, Eastern China. In total, 1163 HIV-infected patients with a median follow-up duration of 27.8 months were included in the analysis. Among them, 261 (22.4%) reported fatigue within the first 6 months after ART. In the multivariable logistic regression analysis, self-reported fatigue within the first 6 months after ART was negatively associated with junior middle-school education or above, baseline CD4 cell count of 200-349 and >350 cells/μL (vs < 200 cells/μL), overweight at baseline (vs normal weight) but positively associated with ≥50 years old at initiation of ART (vs <30 years old), underweight at baseline, use of efavirenz (EFV) in the first-line regimen. Our data suggest that earlier initiation of ART and higher body mass index are preferred to restore the energy of HIV-infected patients with the EFV use in the era of ART in China.

Fatigue symptoms in relation to neuroticism, anxiety-depression, and musculoskeletal pain. A longitudinal twin study

BACKGROUND

The nature of the relationship between fatigue and its risk factors is poorly understood. In the present study the genetic and environmental association between anxiety-depression, musculoskeletal (MS) pain and fatigue was examined, and the role of neuroticism as a shared risk factor that may possibly explain the co-occurrence between these phenotypes was investigated in a combined cross-sectional and longitudinal twin design.

METHODS

The sample consisted of 746 monozygotic (MZ) and 770 dizygotic (DZ) twins in the age group of 50-65 (mean = 57.11 years, SD = 4.5). Continuous measures of fatigue symptoms and the other phenotypes were employed. Using Cholesky modeling, genetic and environmental influences on the phenotypes, and the associations among them, were determined. Analyses were performed using measures of neuroticism obtained concurrently and 13-19 years earlier.

RESULTS

Results from multiple regression analyses showed that neuroticism, anxiety-depression symptoms, and MS pain were all significantly associated with fatigue, controlling for sex, education, and general health indices. The best-fitting biometric models included additive genetic and individual-specific environmental effects. Heritabilities in the 0.40-0.53 range were demonstrated. Furthermore, while there was a considerable overlap in genetic risk factors between the four phenotypes, a substantial proportion of the genetic risk shared between anxiety-depression and fatigue, and between MS pain and fatigue, was independent of neuroticism.

CONCLUSION

Evidence for a common underlying susceptibility to report fatigue symptoms, genetically linked to neuroticism, anxiety-depression, and MS pain, was found. Both unique and pleiotropic effects appear to be involved in the genetic architecture of the phenotypes.

Genetic contributions to self-reported tiredness

Self-reported tiredness and low energy, often called fatigue, are associated with poorer physical and mental health. Twin studies have indicated that this has a heritability between 6 and 50%. In the UK Biobank sample (N=108 976), we carried out a genome-wide association study (GWAS) of responses to the question, 'Over the last two weeks, how often have you felt tired or had little energy?' Univariate GCTA-GREML found that the proportion of variance explained by all common single-nucleotide polymorphisms for this tiredness question was 8.4% (s.e.=0.6%). GWAS identified one genome-wide significant hit (Affymetrix id 1:64178756_C_T; P=1.36 × 10-11). Linkage disequilibrium score regression and polygenic profile score analyses were used to test for shared genetic aetiology between tiredness and up to 29 physical and mental health traits from GWAS consortia. Significant genetic correlations were identified between tiredness and body mass index (BMI), C-reactive protein, high-density lipoprotein (HDL) cholesterol, forced expiratory volume, grip strength, HbA1c, longevity, obesity, self-rated health, smoking status, triglycerides, type 2 diabetes, waist-hip ratio, attention deficit hyperactivity disorder, bipolar disorder, major depressive disorder, neuroticism, schizophrenia and verbal-numerical reasoning (absolute rg effect sizes between 0.02 and 0.78). Significant associations were identified between tiredness phenotypic scores and polygenic profile scores for BMI, HDL cholesterol, low-density lipoprotein cholesterol, coronary artery disease, C-reactive protein, HbA1c, height, obesity, smoking status, triglycerides, type 2 diabetes, waist-hip ratio, childhood cognitive ability, neuroticism, bipolar disorder, major depressive disorder and schizophrenia (standardised β's had absolute values<0.03). These results suggest that tiredness is a partly heritable, heterogeneous and complex phenomenon that is phenotypically and genetically associated with affective, cognitive, personality and physiological processes.

Differential expression of genes and differentially perturbed pathways associated with very high evening fatigue in oncology patients receiving chemotherapy

PURPOSE

Fatigue is the most common symptom associated with cancer and its treatment. Investigation of molecular mechanisms associated with fatigue in oncology patients may identify new therapeutic targets. The objectives of this study were to evaluate the relationships between gene expression and perturbations in biological pathways and evening fatigue severity in oncology patients who received chemotherapy (CTX).

METHODS

The Lee Fatigue Scale (LFS) and latent class analysis were used to identify evening fatigue phenotypes. We measured 47,214 ribonucleic acid transcripts from whole blood collected prior to a cycle of CTX. Perturbations in biological pathways associated with differential gene expression were identified from public data sets (i.e., Kyoto Encyclopedia Gene and Genomes, BioCarta).

RESULTS

Patients were classified into Moderate (n = 65, mean LFS score 3.1) or Very High (n = 195, mean LFS score 6.4) evening fatigue groups. Compared to patients with Moderate fatigue, patients with Very High fatigue exhibited differential expression of 29 genes. A number of the perturbed pathways identified validated prior mechanistic hypotheses for fatigue, including alterations in immune function, inflammation, neurotransmission, energy metabolism, and circadian rhythms. Based on our findings, energy metabolism was further divided into alterations in carbohydrate metabolism and skeletal muscle energy. Alterations in renal function-related pathways were identified as a potential new mechanism.

CONCLUSIONS

This study identified differential gene expression and perturbed biological pathways that provide new insights into the multiple and likely inter-related mechanisms associated with evening fatigue in oncology patients.

A systematic review of the association between fatigue and genetic polymorphisms

Fatigue is one of the most common and distressing symptoms, leading to markedly decreased quality of life among a large subset of patients with a variety of disorders. Susceptibility to fatigue may be influenced by genetic factors including single nucleotide polymorphisms (SNPs), especially in the regulatory regions, of relevant genes. To further investigate the association of SNPs with fatigue in various patient populations, a systematic search was conducted on Pubmed, CINAHL, PsycINFO, and Sociological Abstracts Database for fatigue related-terms in combination with polymorphisms or genetic variation-related terms. Fifty papers in total met the inclusion and exclusion criteria for this analysis. These 50 papers were further classified into three subgroups for evaluation: chronic fatigue syndrome (CFS), cancer-related fatigue (CRF) and other disease-related fatigue. SNPs in regulatory pathways of immune and neurotransmitter systems were found to play important roles in the etiologies of CFS, CRF and other disease-related fatigue. Evidence for associations between elevated fatigue and specific polymorphisms in TNFα, IL1b, IL4 and IL6 genes was revealed for all three subgroups of fatigue. We also found CFS shared a series of polymorphisms in HLA, IFN-γ, 5-HT and NR3C1 genes with other disease-related fatigue, however these SNPs (excluding IFN-γ) were not found to be adequately investigated in CRF. Gaps in knowledge related to fatigue etiology and recommendations for future research are further discussed.

Pathway-focused genetic evaluation of immune and inflammation related genes with chronic fatigue syndrome

Recent evidence suggests immune and inflammatory alterations are important in chronic fatigue syndrome (CFS). This study was done to explore the association of functionally important genetic variants in inflammation and immune pathways with CFS. Peripheral blood DNA was isolated from 50 CFS and 121 non-fatigued (NF) control participants in a population-based study. Genotyping was performed with the Affymetrix Immune and Inflammation Chip that covers 11K single nucleotide polymorphisms (SNPs) following the manufacturer's protocol. Genotyping accuracy for specific genes was validated by pyrosequencing. Golden Helix SVS software was used for genetic analysis. SNP functional annotation was done using SPOT and GenomePipe programs. CFS was associated with 32 functionally important SNPs: 11 missense variants, 4 synonymous variants, 11 untranslated regulatory region (UTR) variants and 6 intronic variants. Some of these SNPs were in genes within pathways related to complement cascade (SERPINA5, CFB, CFH, MASP1 and C6), chemokines (CXCL16, CCR4, CCL27), cytokine signaling (IL18, IL17B, IL2RB), and toll-like receptor signaling (TIRAP, IRAK4). Of particular interest is association of CFS with two missense variants in genes of complement activation, rs4151667 (L9H) in CFB and rs1061170 (Y402H) in CFH. A 5' UTR polymorphism (rs11214105) in IL18 also associated with physical fatigue, body pain and score for CFS case defining symptoms. This study identified new associations of CFS with genetic variants in pathways including complement activation providing additional support for altered innate immune response in CFS. Additional studies are needed to validate the findings of this exploratory study.

Psychometric analysis of the Multidimensional Fatigue Inventory in a sample of persons treated for myocardial infarction

BACKGROUND AND PURPOSE

Fatigue after myocardial infarction is a frequent and distressing symptom in the early recovery phase. The purpose of this study is to psychometrically evaluate the Multidimensional Fatigue Inventory (MFI-20).

METHODS

The MFI-20 was evaluated using Rasch analysis.

RESULTS

The result showed that the MFI-20 can be used to obtain a global score reflecting an underlying unidimensional trait of fatigue; a transformation of the summarized raw scale scores into interval scale scores could be made. Also, 4 of the 5 original dimensions separately fitted the Rasch model.

CONCLUSIONS

Calculation of a global score increases the possibility of identifying persons experiencing fatigue after myocardial infarction, and using the MFI-20 dimension scores increases the possibility of determining each person's specific fatigue profile.

Hyperhomocysteinemia associated skeletal muscle weakness involves mitochondrial dysfunction and epigenetic modifications

HHcy has been implicated in elderly frailty, but the underlying mechanisms are poorly understood. Using C57 and CBS+/- mice and C2C12 cell line, we investigated mechanisms behind HHcy induced skeletal muscle weakness and fatigability. Possible alterations in metabolic capacity (levels of LDH, CS, MM-CK and COX-IV), in structural proteins (levels of dystrophin) and in mitochondrial function (ATP production) were examined. An exercise regimen was employed to reverse HHcy induced changes. CBS+/- mice exhibited more fatigability, and generated less contraction force. No significant changes in muscle morphology were observed. However, there is a corresponding reduction in large muscle fiber number in CBS+/- mice. Excess fatigability was not due to changes in key enzymes involved in metabolism, but was due to reduced ATP levels. A marginal reduction in dystrophin levels along with a decrease in mitochondrial transcription factor A (mtTFA) were observed. There was also an increase in the mir-31, and mir-494 quantities that were implicated in dystrophin and mtTFA regulation respectively. The molecular changes elevated during HHcy, with the exception of dystrophin levels, were reversed after exercise. In addition, the amount of NRF-1, one of the transcriptional regulators of mtTFA, was significantly decreased. Furthermore, there was enhancement in mir-494 levels and a concomitant decline in mtTFA protein quantity in homocysteine treated cells. These changes in C2C12 cells were also accompanied by an increase in DNMT3a and DNMT3b proteins and global DNA methylation levels. Together, these results suggest that HHcy plays a causal role in enhanced fatigability through mitochondrial dysfunction which involves epigenetic changes.

Fatigue in children with juvenile idiopathic arthritis: reliability of the "Pediatric Quality of Life Inventory-Multidimensional Fatigue Scale"

The aim of the study was (1) to translate the "Pediatric Quality of Life Inventory-Multidimensional Fatigue Scale" (PedsQL-Fatigue) into Brazilian Portuguese language and culture and evaluate its reliability and (2) to measure fatigue among patients with juvenile idiopathic arthritis (JIA): (1) Translation of the PedsQL-Fatigue by two bilingual researchers; (2) Backtranslation into English assessed by the authors of the original version; (3) Pilot study with five patients followed in the Pediatric Rheumatology Outpatient Clinic and their parents; and (4) Field study and assessment of measurement properties (internal consistency, reproducibility, and construct validity). In this stage, the scale was administered to 67 patients with JIA and 63 healthy individuals, aged from 2 to 18 years old, matched by age (from 2 to 4, 5 to 7, 8 to 12, and from 13 to 18 years old). Cronbach's alpha coefficient ranged from 0.6 to 0.8 for children and parents, indicating the instrument's good internal consistency. The scale's construct validity was confirmed by a satisfactory Spearman's coefficient between the PedsQL-Fatigue and the generic PedsQL 4.0 (0.840 for the children and 0.742 for the parents). Reproducibility was also adequate (0.764 for the children and 0.938 for the parents). No differences were found between the scores obtained by the JIA group and control group, though lower scores were observed among patients with clinically active JIA when compared to those without clinical activity. The PedsQL-Fatigue is a valid and reliable tool, and that can be used to measure fatigue among patients with JIA.

Fatigue in healthy and diseased individuals

OBJECTIVES

Although fatigue is experienced by everyone, its definition and classification remains under debate.

METHODS

A review of the previously published data on fatigue.

RESULTS

Fatigue is influenced by age, gender, physical condition, type of food, latency to last meal, mental status, psychological conditions, personality type, life experience, and the health status of an individual. Fatigue may not only be a symptom but also a measurable and quantifiable dimension, also known as fatigability. Additionally, it may be classified as a condition occurring at rest or under exercise or stress, as physiologic reaction or pathologic condition, as spontaneous phenomenon or triggerable state, as resistant or irresistant to preconditioning, training, or attitude, as prominent or collateral experience, and as accessible or inaccessible to any type of treatment or intervention. Fatigue may be the sole symptom of a disease or one among others. It may be also classified as acute or chronic. Quantification of fatigability is achievable by fatigue scores, force measurement, electromyography, or other means. Fatigue and fatigability need to be delineated from conditions such as sleepiness, apathy, exhaustion, exercise intolerance, lack of vigor, weakness, inertia, or tiredness. Among neurological disorders, the prevalence of fatigue is particularly increased in multiple sclerosis, amyotrophic lateral sclerosis, Parkinson disease, traumatic brain injury, stroke, and bleeding and also in neuromuscular disorders. Fatigue may be influenced by training, mental preconditioning, or drugs.

CONCLUSIONS

Fatigue needs to be recognized as an important condition that is not only a symptom but may also be quantified and can be modified by various measures depending on the underlying cause.

Biomarkers for chronic fatigue

Fatigue that persists for 6 months or more is termed chronic fatigue. Chronic fatigue (CF) in combination with a minimum of 4 of 8 symptoms and the absence of diseases that could explain these symptoms, constitute the case definition for chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME). Inflammation, immune system activation, autonomic dysfunction, impaired functioning in the hypothalamic-pituitary-adrenal axis, and neuroendocrine dysregulation have all been suggested as root causes of fatigue. The identification of objective markers consistently associated with CFS/ME is an important goal in relation to diagnosis and treatment, as the current case definitions are based entirely on physical signs and symptoms. This review is focused on the recent literature related to biomarkers for fatigue associated with CFS/ME and, for comparison, those associated with other diseases. These markers are distributed across several of the body's core regulatory systems. A complex construct of symptoms emerges from alterations and/or dysfunctions in the nervous, endocrine and immune systems. We propose that new insight will depend on our ability to develop and deploy an integrative profiling of CFS/ME pathogenesis at the molecular level. Until such a molecular signature is obtained efforts to develop effective treatments will continue to be severely limited.

Biomarkers: symptoms, survivorship, and quality of life

OBJECTIVES

To review the evidence on a number of biomarkers that show potential clinical utility in the prediction of and treatment responsiveness for the four most common symptoms associated with cancer and its treatment (ie, pain, fatigue, sleep disturbance, depression).

DATA SOURCES

Review and synthesis of review articles and data-based publications.

CONCLUSION

A growing body of evidence suggests that sensitive and specific biomarkers will be available to assist clinicians with the assessment and management of symptoms.

IMPLICATIONS FOR NURSING PRACTICE

Nurses will play a critical role in educating patients about their risk for specific symptoms based on an evaluation of specific biomarkers. Nurses will be involved in using biomarker data to titrate medications based on patient's responses to symptom management interventions.

[Etiopathogenetic aspects of somatoform disorders]

The etiopathology of somatoform disorders can only be understood against the background of an integrated biopsychosocial model. Cultural and historical influences must be taken into account as well as contemporary settings of scientific or medical priorities. In this context the emphasis on neurobiological findings can be interpreted as the non-accidental struggle for legitimacy of both patients and physicians. Altogether the available data on factors influencing the formation and maintenance of somatoform symptoms has to be described as both diverse and unspecific and thus points to a challenging research program in the coming years.

Minimum data elements for research reports on CFS

Chronic fatigue syndrome (CFS) is a debilitating condition that has received increasing attention from researchers in the past decade. However, it has become difficult to compare data collected in different laboratories due to the variability in basic information regarding descriptions of sampling methods, patient characteristics, and clinical assessments. The issue of variability in CFS research was recently highlighted at the NIH's 2011 State of the Knowledge of CFS meeting prompting researchers to consider the critical information that should be included in CFS research reports. To address this problem, we present our consensus on the minimum data elements that should be included in all CFS research reports, along with additional elements that are currently being evaluated in specific research studies that show promise as important patient descriptors for subgrouping of CFS. These recommendations are intended to improve the consistency of reported methods and the interpretability of reported results. Adherence to minimum standards and increased reporting consistency will allow for better comparisons among published CFS articles, provide guidance for future research and foster the generation of knowledge that can directly benefit the patient.

Myalgic encephalomyelitis: International Consensus Criteria

The label 'chronic fatigue syndrome' (CFS) has persisted for many years because of the lack of knowledge of the aetiological agents and the disease process. In view of more recent research and clinical experience that strongly point to widespread inflammation and multisystemic neuropathology, it is more appropriate and correct to use the term 'myalgic encephalomyelitis' (ME) because it indicates an underlying pathophysiology. It is also consistent with the neurological classification of ME in the World Health Organization's International Classification of Diseases (ICD G93.3). Consequently, an International Consensus Panel consisting of clinicians, researchers, teaching faculty and an independent patient advocate was formed with the purpose of developing criteria based on current knowledge. Thirteen countries and a wide range of specialties were represented. Collectively, members have approximately 400 years of both clinical and teaching experience, authored hundreds of peer-reviewed publications, diagnosed or treated approximately 50 000 patients with ME, and several members coauthored previous criteria. The expertise and experience of the panel members as well as PubMed and other medical sources were utilized in a progression of suggestions/drafts/reviews/revisions. The authors, free of any sponsoring organization, achieved 100% consensus through a Delphi-type process. The scope of this paper is limited to criteria of ME and their application. Accordingly, the criteria reflect the complex symptomatology. Operational notes enhance clarity and specificity by providing guidance in the expression and interpretation of symptoms. Clinical and research application guidelines promote optimal recognition of ME by primary physicians and other healthcare providers, improve the consistency of diagnoses in adult and paediatric patients internationally and facilitate clearer identification of patients for research studies.

Fatigued breast cancer survivors and gene polymorphisms in the inflammatory pathway

Chronic fatigue (CF) in breast cancer survivors (BCSs) has been associated with increased serum C-reactive protein-levels (CRP), pro-inflammatory cytokines and cytokine gene single nucleotide polymorphisms (SNPs). Still, there are few studies on these topics, and due to small study-cohorts the possibility to adjust for other conditions related to inflammatory processes, e.g. depression, has been limited. In 302 BCSs, examined approximately four years after treatment for breast cancer stage II/III, data on high sensitivity (hs)CRP, leukocytes and mRNA interleukin (IL)1β and IL6R expression, depression and chronic fatigue were available. Three years thereafter, 236 BCSs were re-examined. The associations between fatigue and SNPs in inflammation-related genes; IL1β (rs16944), IL6 (rs1800795), IL6receptor (rs4129267, rs4845617, rs2228145), CRP (rs2794521, rs3091244) were investigated, together with the relations between SNPs in IL6R,IL1β and CRP genes and mRNA blood expression levels of IL6R and IL1β and serum hsCRP-levels, respectively. All analyses were repeated after exclusion of depressed individuals and separating BCSs with persistent fatigue from never-fatigued individuals. Even after exclusion of depressed individuals neither the SNPs nor the mRNA IL1β and IL6R expression levels were associated with chronic or persistent fatigue. In the subset of persistent fatigued and never-fatigued individuals the CRP SNP (rs3091244) was associated with hsCRP level (p=0.02). IL1β and IL6R mRNA expression levels were not related to the IL1β and IL6R genotypes. In a large cohort of BCSs the investigated SNPs in inflammation-related genes were not associated with fatigue, though subset analyses indicated an association between the CRP SNP (rs3091244) and serum hsCRP.

DNA methylation of SPARC and chronic low back pain

Background

The extracellular matrix protein SPARC (Secreted Protein, Acidic, Rich in Cysteine) has been linked to degeneration of the intervertebral discs and chronic low back pain (LBP). In humans, SPARC protein expression is decreased as a function of age and disc degeneration. In mice, inactivation of the SPARC gene results in the development of accelerated age-dependent disc degeneration concurrent with age-dependent behavioral signs of chronic LBP.

DNA methylation is the covalent modification of DNA by addition of methyl moieties to cytosines in DNA. DNA methylation plays an important role in programming of gene expression, including in the dynamic regulation of changes in gene expression in response to aging and environmental signals.

We tested the hypothesis that DNA methylation down-regulates SPARC expression in chronic LBP in pre-clinical models and in patients with chronic LBP.

Results

Our data shows that aging mice develop anatomical and behavioral signs of disc degeneration and back pain, decreased SPARC expression and increased methylation of the SPARC promoter. In parallel, we show that human subjects with back pain exhibit signs of disc degeneration and increased methylation of the SPARC promoter. Methylation of either the human or mouse SPARC promoter silences its activity in transient transfection assays.

Conclusions

This study provides the first evidence that DNA methylation of a single gene plays a role in chronic pain in humans and animal models. This has important implications for understanding the mechanisms involved in chronic pain and for pain therapy.

An Etiological Model for Myalgic Encephalomyelitis/Chronic Fatigue Syndrome

Kindling might represent a heuristic model for understanding the etiology of Myalgic Encephalomyelitis/chronic fatigue syndrome (ME/CFS). Kindling occurs when an organism is exposed repeatedly to an initially sub-threshold stimulus resulting in hypersensitivity and spontaneous seizure-like activity. Among patients with ME/CFS, chronically repeated low-intensity stimulation due to an infectious illness might cause kindling of the limbic-hypothalamic-pituitary axis. Kindling might also occur by high-intensity stimulation (e.g., brain trauma) of the limbic-hypothalamic-pituitary axis. Once this system is charged or kindled, it can sustain a high level of arousal with little or no external stimulus and eventually this could lead to hypocortisolism. Seizure activity may spread to adjacent structures of the limbic-hypothalamic-pituitary axis in the brain, which might be responsible for the varied symptoms that occur among patients with ME/CFS. In addition, kindling may also be responsible for high levels of oxidative stress, which has been found in patients with ME/CFS.

What is fatigue? Pathological and nonpathological fatigue

Aid in understanding issues surrounding the construct validity of fatigue including the distinction between pathological versus nonpathological fatigue. Fatigue is a universal symptom reported by individuals in the general population as well as by those suffering from different medical and psychological illnesses, including cancer, multiple sclerosis, chronic fatigue syndrome, depression, and anxiety. Chronic fatigue is a significant problem in many primary care settings, and the debilitating and prolonged nature of fatigue can pose significant economic consequences for society. Researchers have struggled to better assess and understand the etiology and classification of fatigue within different illness groups.