What is fatigue? Pathological and nonpathological fatigue

Study of Fatigue and Associated Factors in Traumatic Brain Injury and Its Correlation with Insomnia and Depression

Introduction:

Fatigue has been cited as a common problem associated with traumatic brain injury. A positive association of fatigue has been suggested with insomnia and depression which are also considered to be significantly associated with traumatic brain injury.

Aims and Objectives:

The present study in post-traumatic brain injury patients is planned to assess the prevalence of fatigue, depression and insomnia, the correlation of fatigue with depression and insomnia and the risk factors associated with fatigue.

Material and Methodology:

Total 100 patients were recruited in the present study. Interview was focused on assessment of severity of traumatic brain injury, fatigue, insomnia and depression using Glasgow Coma Scale, Fatigue Severity Scale, Insomnia Severity Index and Patients Health Questionnaire(PHQ-9) respectively.

Results:

Prevalence of depression was found 84% while that of fatigue and insomnia was 50% and 49% respectively. All patients with fatigue had depression whereas those patients without fatigue were also found to have depression (68%) and this correlation was found statistically significant. Similarly, insomnia was reported in 70% of patients who were fatigued against 28% of patients with no fatigue. This was also found statistically significant (P <0.0002).

Conclusion:

Fatigue in common in post TBI patients. Insomnia and depression are closely associated with fatigue. Clinical and research investigations of fatigue in post-traumatic brain injury should include concomitant screening for treatable depressive symptoms and sleep disorders.

A correlation between sickness or injury within two weeks, chronic diseases and fatigue among adults aged 18-45 years

To investigate the prevalence of fatigue, the relationship between sickness or injury within two weeks, chronic diseases and fatigue among adults aged 18-45 years. Thousand five hundred and seventy nine individuals were included in this cross-sectional study. The Chalder Fatigue Scale (CFS) was used to assess fatigue defined as CFS score ≥4. The prevalence of fatigue was 25% in this study. Our results showed that only sickness or injury within two weeks (odds ratio [OR]: 2.440) and chronic diseases (OR: 1.727) were significantly related to fatigue. Moreover, their ORs for fatigue remained the same in all models (binary logistic regression models with adjusting for demographic and health-related characteristics one by one). In conclusion, fatigue was prevalent among adults aged 18-45 years. Sickness or injury within two weeks and chronic diseases were the risk factors for fatigue independent of demographic and health-related characteristics.

High fatigue and its associations with health and work related factors among female medical personnel at 54 hospitals in Zhuhai, China

The present study aimed to investigate the prevalence of fatigue and determine factors associated with fatigue in female medical personnel. Based on a cross-sectional study, a total of 1608 female medical personnel at 54 hospitals in Zhuhai, China were recruited by a multistage stratified cluster sampling method. The Symptoms Checklist-90-Revised and Chalder Fatigue Scale were used to assess psychiatric symptoms and fatigue, respectively. Data regarding demographic, health, and work related variables were also collected. Multivariate logistic regression model was constructed to determine the influencing factors of fatigue. Approximately 83% of participants had experienced fatigue in the past week. The risk of fatigue was higher in aged 30-39 years old than older or younger participants; Longer sleeping time predicted a lower prevalence of fatigue (OR = .35), while tense physician-patient relationship predicted a higher prevalence of fatigue (OR = 1.77). Depression (OR = 1.76) and anxiety (OR = 1.96) were found related to fatigue. Additionally, fatigue was associated with marital status, occupation, health related factors (exercise, regular diet, and health status), and work related factors (hospital rank and turnover intention). These study findings might facilitate development and implementation of targeted interventions and preventive measures.

Sustained Attention in Real Classroom Settings: An EEG Study

Sustained attention is a process that enables the maintenance of response persistence and continuous effort over extended periods of time. Performing attention-related tasks in real life involves the need to ignore a variety of distractions and inhibit attention shifts to irrelevant activities. This study investigates electroencephalography (EEG) spectral changes during a sustained attention task within a real classroom environment. Eighteen healthy students were instructed to recognize as fast as possible special visual targets that were displayed during regular university lectures. Sorting their EEG spectra with respect to response times, which indicated the level of visual alertness to randomly introduced visual stimuli, revealed significant changes in the brain oscillation patterns. The results of power-frequency analysis demonstrated a relationship between variations in the EEG spectral dynamics and impaired performance in the sustained attention task. Across subjects and sessions, prolongation of the response time was preceded by an increase in the delta and theta EEG powers over the occipital region, and decrease in the beta power over the occipital and temporal regions. Meanwhile, implementation of the complex attention task paradigm into a real-world classroom setting makes it possible to investigate specific mutual links between brain activities and factors that cause impaired behavioral performance, such as development and manifestation of classroom mental fatigue. The findings of the study set a basis for developing a system capable of estimating the level of visual attention during real classroom activities by monitoring changes in the EEG spectra.

Demonstration of two types of fatigue in subjects with chronic liver disease using factor analysis

PURPOSE

The purpose of this investigation was to determine if it was possible to separate fatigue self-reports into two distinct types of fatigue symptom clusters in research subjects with chronic liver disease (CLD). It was hypothesized that when items from the Medical Outcomes Study Short-Form (SF-36v2) are combined with items from the Fatigue Severity Scale (FSS), these distinct factors will emerge.

METHODS

Confirmatory and exploratory factor analyses from data collected in a prospective, natural history study of CLD patients were conducted. Items were selected from the SF-36v2 and the FSS for entry into the factor analyses. In order to establish convergent and discriminant validity, derived factor scores were correlated with subscale scores of the Human Activity Profile (HAP), Mental Component Score (MCS) from the SF-36v2, and the Emotional Functioning Subscale of the Chronic Liver Disease Questionnaire (CLDQ-EF).

RESULTS

106 participants with CLD were included (50% female; age: 51 ± 10). Two factors were identified. The factors included one that clustered around questions addressing fatigue related to physical activity (peripheral fatigue) and the other to the questions addressing generalized fatigue that did not require physical tasks to produce the fatigue (central fatigue). The standardized factor loadings of all items were greater than 0.6 on their underlying constructs. Moreover, all factor loadings are significant at p < 0.01. Peripheral fatigue was related to HAP (r = 0.26, r = 0.24, p < 0.01), as was central fatigue (r = -0.34, r = -0.33, p < 0.01). Central fatigue was related to MCS and CLDQ-EF (r = -0.60; r = -0.63, p < 0.01), whereas peripheral fatigue was not (r = 0.07, p > 0.40). We then tested the original scales to determine if the newly created factors correlated better with the validity measures. The full FSS did not correlate as well as the newly created central fatigue scale, while the original peripheral fatigue scale (the SF-36v2 physical functioning) was more related to HAP than the newly created scale.

CONCLUSIONS

In individuals with CLD, two separate factors pertaining to fatigue were identified. This recognition of the multifaceted nature of fatigue may help increase the specificity of self-reports of fatigue and lead to treatments that can specifically address the underlying factors contributing to fatigue.

Acupuncture and Moxibustion have Different Effects on Fatigue by Regulating the Autonomic Nervous System: A Pilot Controlled Clinical Trial

In order to investigate the different effects of acupuncture and moxibustion on chronic fatigue syndrome (CFS) and alterations in the autonomic nervous system by measuring heart rate variability (HRV). Forty-five participants were recruited and randomly divided into 3 groups using a randomization schedule. The control group (CG, n = 15) and the acupuncture group (AG, n = 15) were treated by manipulation acupuncture, and the moxibustion group (MG, n = 15) was treated by indirect moxibustion. Primary outcomes were the scores of the Fatigue Assessment Instrument (FAI). Secondary outcomes were the HRV parameters which can reflect activity of the autonomic nervous system. This trial considered both instantaneous changes and long-term effectiveness. FAI scores decreased after the 4th and 10th treatments in the 3 groups. The decrease in FAI in the MG was greater than that in the AG. Acupuncture was more effective in instantaneous changes of HRV and moxibustion in long-term aspects. Both acupuncture and moxibustion improved fatigue in CFS patients, but moxibustion was more effective. The possible mechanism of the intervention may be through activation of the vagus nerve. Moxibustion was more effective than acupuncture in long-term treatment of CFS.

The extent of using mobility assistive devices can partly explain fatigue among persons with late effects of polio - a retrospective registry study in Sweden

Background

Fatigue is reported as one of the most disabling symptoms and is common among persons living with late effects of polio. Although fatigue has been studied in the context of people living with late effects of polio, there is a lack of knowledge concerning the association of fatigue and variables of importance for participation in daily life. Therefore, the aim of this study was to explore possible factors associated with fatigue among persons with late effects of polio in Sweden.

Methods

This retrospective registry study consisted of 89 persons with late effects of polio living in Sweden. Fatigue was measured with the Multidimensional Fatigue Inventory (MFI-20) scale, Swedish version. Pearson’s correlation coefficient was used to analyse the correlation between the factors and fatigue, and a multiple linear regression was carried out to explore factors for fatigue.

Results

Fatigue statistically significantly correlated with age (r = 0.234, p < 0.05) and the use of mobility assistive devices (r = 0.255, p < 0.05). The multiple linear regression model showed that the factors age (β = 0.304, p < 0.019) and mobility assistive devices (β = 0.262, p < 0.017) were associated with fatigue among persons living with late effects of polio, and the model partly explained 14% of the variation of fatigue.

Conclusions

Fatigue could partly be explained by the extent of using mobility assistive devices and age. Healthcare professionals should provide and demonstrate the importance of assistive devices to ensure management of fatigue in persons living with late effects of polio.

Clinical Presentation of Anxiety in Parkinson's Disease: A Scoping Review

Up to 40% of all individuals with Parkinson's disease (PD) are estimated to experience anxiety that interferes with daily functioning. This article describes research regarding the presentation of anxiety in PD and the influence anxiety has on participation in this population. A scoping review identified 1,635 articles, of which 49 met the inclusion criteria. This review identified that anxiety in PD is often associated with a range of clinical correlates related to demographic and clinical characteristics (age, gender, disease stage, duration, progression), motor symptoms (tremor, bradykinesia, dystonia, freezing of gait, symptom severity), treatment-related complications (on/off fluctuations, on with dyskinesia, unpredictable off), and non-motor symptoms (sleep abnormalities, fatigue, cognitive impairment, depression). These findings can be used to increase clinicians' awareness toward the specific clinical correlates linked to anxiety in PD so that mental health concerns can be detected and addressed more readily in practice.

Fatigue as a manifestation of psychosocial distress in a low-income country: a population-based panel study

OBJECTIVE

Fatigue is a common complaint worldwide and associated with disability and high health service use costs. We tested the hypothesis that maternal fatigue would be associated independently with maternal common mental disorder ('maternal CMD') in a rural, low-income country setting.

METHODS

The analysis was conducted using data from a population-based cohort located in the Butajira demographic surveillance site, Ethiopia. A total of 1065 women were recruited in pregnancy and followed up to 2.5 (n = 1009; 94.7%) and 3.5 years post-partum (n = 989; 92.9%). Maternal CMD symptoms were measured using a locally validated version of the Self-Reporting Questionnaire and fatigue was measured using a dichotomised item from the Patient Health Questionnaire-15. Physical health indicators included haemoglobin level, body mass index and illness episodes. Generalised estimating equations were used to conduct hypothesis-driven and exploratory multivariable analyses in the panel at 2.5 and 3.5 years.

RESULTS

The prevalence of maternal fatigue was 8.3% at 2.5 years and 5.5% at 3.5 years post-partum. Psychological symptoms of maternal CMD were associated independently with complaints of fatigue after adjusting for anaemia, body mass index, physical ill health, poverty and other confounding variables: adjusted odds ratio (aOR), 1.46; 95% confidence interval (CI), 1.28-1.66 for each one point increase in SRQ score. In the multivariable model, only psychosocial factors (CMD and stressful life events) and self-reported physical ill health were associated significantly with complaints of fatigue.

CONCLUSION

Complaints of fatigue are associated strongly with maternal CMD and other psychosocial risk factors in this rural, low-income country setting with a high burden of undernutrition and infectious disease. Fatigue should be understood as a potential indicator of CMD in primary care to improve detection and treatment.

Effects of Viral Eradication With Ledipasvir and Sofosbuvir, With or Without Ribavirin, on Measures of Fatigue in Patients With Chronic Hepatitis C Virus Infection

BACKGROUND & AIMS

Fatigue is a disturbing symptom of chronic hepatitis C virus (HCV) infection. We assessed the effects of sustained virologic response 12 weeks after the end of therapy (SVR12) on fatigue.

METHODS

We performed a retrospective analysis of 100 patients with chronic HCV infection who achieved an SVR12 after treatment with ledipasvir and sofosbuvir, with or without ribavirin. Data were collected on fatigue-related patient-reported outcomes (PROs) and assessed by using the Functional Assessment of Cancer Therapy-Fatigue scoring system and the Vitality subscale of Short Form 36. We measured levels of cytokines and growth factors in frozen serum samples collected at baseline, week 12 of treatment, and 4 weeks after treatment. Central fatigue and peripheral or muscle fatigue (PF) were determined by using items from PROs. Serum levels of cytokines, growth factors, serotonin, alanine aminotransferase, and aspartate aminotransferase were measured by using the Bio-Plex, enzyme-linked immunosorbent, and enzymatic assays.

RESULTS

Compared with baseline, 4 weeks after the end of treatment, all fatigue-associated PROs improved significantly. Baseline PROs correlated inversely with serum level of interferon-γ; level of platelet-derived growth factor correlated with PF, central fatigue, and total fatigue score. Only PF correlated with serum level of serotonin. At baseline, high PF scores correlated with high serum levels of serotonin and low levels of interleukin-10 and tumor necrosis factor-α. In multivariate analysis, serum level of interleukin-8 was associated with greater fatigue (P < .02). Reductions in levels of chemokine (C-C motif) ligand 2 (also called monocyte chemotactic protein 1) were associated with fatigue after treatment (P = .0165).

CONCLUSIONS

In an analysis of data from patients with chronic HCV infection participating in a clinical trial of ledipasvir and sofosbuvir, SVR12 was associated with reduced fatigue, compared with baseline. High baseline serum levels of interferon-γ were associated with fatigue. Reductions in levels of chemokine (C-C motif) ligand 2 were associated with persistent fatigue after SVR12. Central and peripheral fatigue each associated with different biomarkers, suggesting different pathogenic pathways.

Fatigue in early axial spondyloarthritis. Results from the French DESIR cohort

INTRODUCTION

Fatigue is frequent in long-standing axial spondyloarthritis (axSpA); its frequency in early axSpA and its causes are unclear. The objective was to evaluate the magnitude of fatigue in early axSpA and to assess if fatigue appeared more strongly associated with patient- or with disease-related characteristics.

METHODS

Patients were assessed in DESIR, a national observational cohort of patients with recent (<3 years duration) inflammatory back pain suggestive of axSpA. Magnitude of fatigue was assessed by a numeric rating scale (0-10) over one year. Factors associated with high fatigue (≥5/10) at 12 months were assessed by univariate and multivariate logistic regression, for patients fulfilling the ASAS axSpA criteria.

RESULTS

Of the 708 patients, 486 fulfilled the ASAS criteria for axSpA: mean age 33±9 years; 244 (50%) males. Magnitude of fatigue was high at baseline (mean fatigue: 5.7±2.3) and decreased only slightly over the first year, and was overlapping in patients fulfilling the ASAS criteria or not. High fatigue at 12 months was well explained (variance explained: 0.84) by a higher ASDAS-CRP (odds ratio [OR]: 3.05 [95% confidence interval (CI) 2.27-4.12], P<0.0001), higher Bath Anylosing Spondylitis Patient Global (BAS-G) (OR: 3.51 [95% CI, 2.08-6.02], P<0.0001) and with borderline significance, female gender (OR: 1.65 [95% CI, 1.00-2.71], P=0.049).

CONCLUSION

Fatigue levels were high in this population, both for patients fulfilling or not, the ASAS criteria for axSpA. High fatigue was closely related to disease-related variables, indicating fatigue may be an integral part of the disease process in axSpA.

A community-based cross-sectional study of fatigue in middle-aged and elderly women

BACKGROUND

Fatigue has been widely studied in the general population; however, limited studies have investigated it in the female population. The objectives of this community-based study were to (1) investigate the prevalence of fatigue, (2) explore the relationship between gynecological history and experiences of fatigue, and (3) identify risk factors for fatigue in middle-aged and elderly women.

METHODS

Based on a cross-sectional health study that employed a multi-instrument questionnaire, 1272 women aged 45years or older dwelling in the community were included. The Chinese version of Chalder Fatigue Scale (CFS) was used to assess fatigue, and socio-demographic, health-related, and gynecological data were also collected. Fatigue was defined as a total CFS score≥4.

RESULTS

The prevalence of fatigue among women aged over 45years was 33.9%. Multivariate logistic regression analysis identified that older age, single marital status, lower education level, the presence of chronic diseases, underweight, hospitalization in the last year, postmenopause, and a higher number of live births were associated with an increased risk of fatigue (P<0.05).

CONCLUSIONS

Our results indicated that fatigue was common in middle-aged and elderly females. Being postmenopausal and having more than three live births were the particular gynecological factors contributing to fatigue in the general population.

Experiences with, perceptions of and attitudes towards traditional Korean medicine (TKM) in patients with chronic fatigue: a qualitative, one-on-one, in-depth interview study

OBJECTIVES

To explore perceptions and experiences of patients with chronic fatigue with traditional Korean medicine (TKM) and their motivation for choosing TKM.

DESIGN

Qualitative, one-on-one, in-depth interview study.

SETTING

Primary TKM hospitals in Seoul, Incheon and Daejeon, South Korea.

RESULTS

15 patients with chronic fatigue were interviewed in this study. Patients with chronic fatigue experienced physical and psychological symptoms that resulted in severe difficulties associated with routine daily activities. The motivations for choosing TKM were primarily dissatisfaction with conventional medicine and previous positive experiences with TKM. While undergoing TKM treatment, patients found that TKM practitioners considered fatigue to be a treatable illness; also, patients felt comfortable with the doctor-patient relationship in TKM.

CONCLUSIONS

Healthcare providers need to be concerned about the symptoms of chronic fatigue to a degree that is in line with the patient's own perceptions. Korean patients with chronic fatigue choose TKM as an alternative to fulfil their long-term needs that were unmet by conventional medicine, and they are greatly positively influenced by TKM. TKM may present a possible therapy to alleviate symptoms of diseases that conventional medicine does not address and is an approach that has a considerable effect on Korean patients.

Factors Associated with Fatigue among Men Aged 45 and Older: A Cross-Sectional Study

Background and Purpose: Fatigue is one of the most common symptoms reported in several studies; but few studies have concentrated on the male population, especially for the middle-aged and older men who are exposed to greater fatigue risk. The purpose of this study was to explore the prevalence of fatigue and identify the risk factors of fatigue among men aged 45 and older in China. Methods: This study was part of a cross-sectional study on community health in Shunde (Guangdong Province, China). A total sample of 1158 men aged 45 and older were included. Sociodemographic characteristics, health and lifestyle factors and the Chalder Fatigue Scale (CFS) were measured by structured questionnaires through face-to-face interviews. Multivariate logistic regression was applied to determine the risk factors of fatigue. Results: Approximately 30% of participants experienced fatigue. Older age (≥75 years: adjusted OR 3.88, 95% CI 2.09–7.18), single marital status (1.94, 1.04–3.62), unemployed status (1.68, 1.16–2.43), number of self-reported chronic diseases (≥2 chronic diseases: 2.83, 1.86–4.31), number of individuals’ children (≥4 children: 2.35, 1.33–4.15), hospitalization in the last year (1.61, 1.03–2.52) were all significantly associated with increased risk of fatigue, while regular exercise (0.46, 0.32–0.65) was a protective factor against fatigue. Conclusions: Fatigue was usual in males and several factors were associated with the fatigue. These findings may have implication in risk assessment of fatigue and help in developing and implementing targeted interventions in middle-aged and elderly males.

Development of a clinician-administered National Institutes of Health-Brief Fatigue Inventory: A measure of fatigue in the context of depressive disorders

OBJECTIVE

Fatigue is a complex, multidimensional condition. Although it is often associated with depression, it is not known whether it has a distinct network from depression or whether it can be clinically evaluated, separately. This study describes preliminary findings in the development of a brief, clinician-administered instrument to measure fatigue in the context of depressive disorders using items from existing clinician-administered depression and mania scales.

METHODS

Based on items from prior fatigue measurements, items were selected from the Hamilton Depression Rating Scale (HDRS), Montgomery-Asberg Depression Rating Scale (MADRS), Young Mania Rating Scale, and Structured Interview Guide for HDRS with Atypical Depression. The final items composed the NIH-Brief Fatigue Inventory (NIH-BFI). Responses from 89 depressed adults collected pre- and post-antidepressant therapy (ADT) determined the reliability and consistency of the NIH-BFI using Cronbach's alpha and principal components analysis (PCA). Correlations of the NIH-BFI and fatigue items from other scales before and after ADT explored validity.

RESULTS

The 7-item NIH-BFI had Cronbach alphas ranging from 0.81 to 0.88 and PCA indicating a single dimension. The NIH-BFI score was strongly correlated (r = 0.73, p < 0.001) with fatigue items from Beck Depression Index, with MADRS without fatigue items (r = 0.77, p < 0.001), and HDRS without fatigue items (pre: r = 0.69, p < 0.001).

CONCLUSIONS

Preliminary findings show support for internal consistency reliability and validity of the NIH-BFI, a clinician-administered measure of fatigue. Further testing in other clinical populations is recommended to obtain additional information on reliability and validity. The NIH-BFI provides a method for clinician-rated fatigue that may be a separate from depression.

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.

Post-thyroidectomy chronic asthenia: self-deception or disease?

There is clinical evidence that post-total thyroidectomy (TT) patients can present persistent asthenia. The aim of this study was to evaluate the prevalence of asthenia symptoms in such patients, assess whether a chronic asthenia syndrome could be caused by TT or become evident after it. An observational study was carried out comparing two groups of 100 patients each, all with homogeneous characteristics. Group A was treated with total lobectomy (TL), Group B with TT. All patients presented normal thyroid hormone levels. The patients were interviewed in order to identify the ones affected by post-operative asthenia persisting for at least six months, with reduced ability to perform physical and mental work, not showing improvement with rest. The severity of the symptoms has been measured by means of the brief fatigue inventory (BFI). Statistical analysis was performed to evaluate statistically significative differences between groups and prognostic factors in TT group. The incidence of post-operative asthenia was 0 % after TL and 25 % after TT, with the operation being the only significant variable. Asthenia is well known as symptom of post-thyroidectomy, but it has not been adequately investigated as consequence of surgery. We demonstrated that the complete removal of the thyroid gland could determine chronic post-thyroidectomy asthenia, although with intensity limited to low/moderate. Post-thyroidectomy asthenia is a relevant sequela interfering with quality of life of at least 25 % of patients operated, suggesting the need to identify its real causes and limit the indication to TT only when strictly required.

A systematic review of fatigue in patients with traumatic brain injury: the course, predictors and consequences

BACKGROUND

Fatigue is common after traumatic brain injury (TBI). Its risk factors, natural history and consequences are uncertain. Best-evidence synthesis was used to address the gaps.

METHODS

Five databases were searched for relevant peer-reviewed studies. Of the 33 articles appraised, 22 longitudinal studies were selected. Results were reported separately based on their timing of baseline assessment.

RESULTS

All studies document changes in fatigue frequency and severity with time, irrespective of setting or TBI severity. There is limited evidence for certain clinical and psychosocial variables as predictors of fatigue severity at follow-up. Early fatigue severity predicted persistent post-concussive symptoms and Glasgow outcome score at follow-up.

CONCLUSIONS

Fatigue is present before and immediately following injury, and can persist long term. The variation in findings supports the idea of fatigue in TBI as a nonhomogeneous entity, with different factors influencing the course of new onset or chronic fatigue. To decrease the heterogeneity, we emphasize the need for agreement on a core set of relevant fatigue predictors, definitions and outcome criteria. PROSPERO registry number: CRD42013004262.

Association of Mitochondrial Dysfunction and Fatigue: A Review of the Literature

Fatigue is often described by patients as a lack of energy, mental or physical tiredness, diminished endurance, and prolonged recovery after physical activity. Etiologic mechanisms underlying fatigue are not well understood; however, fatigue is a hallmark symptom of mitochondrial disease, making mitochondrial dysfunction a putative biological mechanism for fatigue. Therefore, this review examined studies that investigated the association of markers of mitochondrial dysfunction with fatigue and proposes possible research directions to enhance understanding of the role of mitochondrial dysfunction in fatigue. A thorough search using PubMed, Scopus, Web of Science, and Embase databases returned 1,220 articles. After application of inclusion and exclusion criteria, a total of 25 articles meeting eligibility criteria were selected for full review. Dysfunctions in the mitochondrial structure, mitochondrial function (mitochondrial enzymes and oxidative/nitrosative stress), mitochondrial energy metabolism (ATP production and fatty acid metabolism), immune response, and genetics were investigated as potential contributors to fatigue. Carnitine was the most investigated mitochondrial function marker. Dysfunctional levels were reported in all the studies investigating carnitine; however, the specific type of carnitine that was dysfunctional varied. Genetic profiles were the second most studied mitochondrial parameter. Six common pathways were proposed: metabolism, energy production, protein transport, mitochondrial morphology, central nervous system dysfunction and post-viral infection. Coenzyme Q10 was the most commonly investigated mitochondrial enzyme. Low levels of Coenzyme Q10 were consistently associated with fatigue. Potential targets for further investigation were identified as well as gaps in the current literature.

Validity of the multidimensional fatigue symptom inventory-short form in an African-American community-based sample

OBJECTIVES

This study examined the psychometric properties of the Multidimensional Fatigue Symptom Inventory-Short Form (MFSI-SF) in a community-based sample of African-Americans.

DESIGN

A sample of 340 African-Americans (116 men, 224 women) ranging in age from 18-81 years were recruited from the community (e.g., churches, health fairs, and beauty salons). Participants completed a brief demographic survey, the MFSI-SF and the Positive and Negative Affect Schedule.

RESULTS

The structural validity of the MFSI-SF for a community-based sample of African-Americans was not supported. The five dimensions of fatigue (General, Emotional, Physical, Mental, Vigor) found for Whites in prior research were not found for African-Americans in this study. Instead, fatigue, while multidimensional for African-Americans, was best represented by a unique four-four profile in which general and emotional fatigue are collapsed into a single dimension and physical fatigue, mental fatigue, and vigor are relatively distinct. Hence, in the absence of modifications, the MFSI-SF cannot be considered to be structurally invariant across ethnic groups. A modified four-factor version of the MFSI-SF exhibited excellent internal consistency reliability and evidence supports its convergent validity. Using the modified four-factor version, gender, and age were not meaningfully associated with MFSI-SF scores.

CONCLUSION

Future research should further examine whether modifications to the MFSI-SF would, as the findings suggest, improve its validity as a measure of multidimensional fatigue in African-Americans.

Impact of comorbidity on fatigue management intervention outcomes among people with multiple sclerosis: an exploratory investigation

This exploratory secondary analysis examined whether the presence of six chronic health conditions moderated the effectiveness of a teleconference-delivered fatigue self-management education program for people with multiple sclerosis (MS). The longitudinal data used were from a randomized controlled trial involving 181 community-dwelling adults with MS. The primary outcome was fatigue impact, as measured by the Fatigue Impact Scale (FIS). Mixed-effects analysis of variance (ANOVA) models were used to determine the best-fitting model. Just under 65% (n = 112) of participants had at least one comorbid condition. Only diabetes and arthritis moderated all three FIS subscales over time. People with diabetes were slower to show improvement after intervention than people without diabetes. People with arthritis made much more dramatic initial gains compared with people without arthritis but had difficulty maintaining those gains over time. The results point to the need for greater attention to the impact of comorbidities on rehabilitation interventions. These exploratory findings suggest that fatigue self-management education protocols may need to be customized to people who are trying to incorporate MS fatigue self-management behaviors while simultaneously managing diabetes or arthritis.

Visual fatigue effects on vergence dynamics in asymptomatic individuals

PURPOSE

To evaluate objectively changes in vergence dynamics following intentional visual fatiguing tasks using congruent (C) and non-congruent (NC) vergence stimulus demands.

METHODS

Pre- and post-task vergence dynamics to a 10.3° disparity stimulus were recorded objectively in 12 adult, asymptomatic individuals for both convergence and divergence. There were two fatigue-inducing tasks: Congruent or C-task: Subjects altered bifixation (50 cycles) between reduced Snellen charts at 2 m and at 20 cm every 3 s. Non-congruent or NC task: Subjects performed 50 cycles of vergence flipper (7Δ BO/BI), while bifixating a reduced Snellen chart at 40 cm. Pre- and post-task mean amplitude, time constant, peak velocity, and steady-state response variability were compared.

RESULTS

There was a significant increase in mean post-task, steady-state response variability for both the C and NC tasks. However, there were no significant group differences for either convergence or divergence between the pre- and post-mean amplitude, time constant, and peak velocity parameters for both the C and NC tasks, although post-task peak velocity was consistently reduced.

CONCLUSIONS

Steady-state vergence response variability was found to be the critical objective parameter to demonstrate significant fatigue effects in the group. Peak velocity was also consistently reduced to a small extent in the NC task. We speculate that these fatigue effects are of a central, and not of peripheral, origin.

Fatigue and fatigability in neurologic illnesses: proposal for a unified taxonomy

Fatigue is commonly reported in many neurologic illnesses, including multiple sclerosis, Parkinson disease, myasthenia gravis, traumatic brain injury, and stroke. Fatigue contributes substantially to decrements in quality of life and disability in these illnesses. Despite the clear impact of fatigue as a disabling symptom, our understanding of fatigue pathophysiology is limited and current treatment options rarely lead to meaningful improvements in fatigue. Progress continues to be hampered by issues related to terminology and assessment. In this article, we propose a unified taxonomy and a novel assessment approach to addressing distinct aspects of fatigue and fatigability in clinical and research settings. This taxonomy is based on our current knowledge of the pathophysiology and phenomenology of fatigue and fatigability. Application of our approach indicates that the assessment and reporting of fatigue can be clarified and improved by utilizing this taxonomy and creating measures to address distinct aspects of fatigue and fatigability. We review the strengths and weaknesses of several common measures of fatigue and suggest, based on our model, that many research questions may be better addressed by using multiple measures. We also provide examples of how to apply and validate the taxonomy and suggest directions for future research.

A qualitative natural history study of ME/CFS in the community

In previous qualitative research on Myalgic Encephalomyelitis/chronic fatigue syndrome (ME/CFS), researchers have focused on the experiences of patients with ME/CFS in tertiary care samples. This qualitative study examined the natural history of people with ME/CFS (n = 19) from a community-based sample. Findings highlighted multilayered themes involving the illness experience and the physical construction of ME/CFS. In addition, this study further illuminated unique subthemes regarding community response and treatment, which have implications for understanding the progression of ME/CFS as well as experiences of those within patient networks. There is a need for more longitudinal qualitative research on epidemiological samples of patients with ME/CFS.

Fatigability as a function of physical activity energy expenditure in older adults

Increased fatigue is a predictor of morbidity and mortality in older adults. Fatigability defines a change in performance or self-reported fatigue in response to physical activity (PA). However, the relationship of fatigability to PA-related energy expenditure (PAEE) is unknown. Changes in performance, fatigue, and energy expenditure were measured simultaneously in 17 adults (11 females, 74-94 years old) performing eight standardized PA tasks with various energy expenditure requirements in a whole-room indirect calorimeter. Change in performance was objectively measured using a PA movement monitor and change in fatigue was self-reported on a seven-point scale for each task. Performance and perceived fatigability severity scores were calculated as a ratio of change in performance and fatigue, respectively, and PAEE. We found that change in both objective performance and self-reported fatigue were associated with energy expenditure (Spearman rho = -0.72 and -0.68, respectively, p < 0.001) on a task requiring relatively high level of energy expenditure. The performance and perceived fatigability severity scores were significantly correlated (rho = 0.77, p < 0.001) on this task. In summary, results of this proof of concept pilot study show that both perceived and performance fatigability severity scores are related to PAEE-induced fatigue on a task requiring relatively high level of energy expenditure. We conclude that fatigability severity is a valid measure of PAEE-induced fatigue in older adults.

Personality and fatigue perception in a sample of IBD outpatients in remission: a preliminary study

BACKGROUND AND AIMS

Fatigue is considered as a feature of IBD. Nevertheless, medical variables would partly explain this complex phenomenon. Psychological variables would be especially connected to fatigue for patients in remission. Moreover, personality is known to be linked to the fatigue of patients with CFS. This preliminary study aimed to determine if personality dimensions are linked to the perception of fatigue in IBD.

METHODS

81 IBD outpatients in remission completed the MFI (fatigue); ISI, EES (sleep disturbances); TCI-R (personality); HADS (depression and anxiety). Medical data were collected (ferritin, C-reactive protein, number of flare-ups, number of hospitalizations, duration of the disease and surgical sequelae).

RESULTS

With the exception of surgical sequelae, none of the medical variables was linked to fatigue perception. Anxiety and sleep disturbances were the most continuously connected to fatigue perception. Significant relationships were observed between personality categorization on Persistence, Self-Directness and the level of fatigue.

CONCLUSION

In order to improve vitality in IBD patients in remission, identification and treatment of psychological aspects should become a dimension of disease management. Fatigue should not be considered only as a direct feature of IBD.

Complementary and alternative medicine for patients with chronic fatigue syndrome: a systematic review

Background

Throughout the world, patients with chronic diseases/illnesses use complementary and alternative medicines (CAM). The use of CAM is also substantial among patients with diseases/illnesses of unknown aetiology. Chronic fatigue syndrome (CFS), also termed myalgic encephalomyelitis (ME), is no exception. Hence, a systematic review of randomised controlled trials of CAM treatments in patients with CFS/ME was undertaken to summarise the existing evidence from RCTs of CAM treatments in this patient population.

Methods

Seventeen data sources were searched up to 13th August 2011. All randomised controlled trials (RCTs) of any type of CAM therapy used for treating CFS were included, with the exception of acupuncture and complex herbal medicines; studies were included regardless of blinding. Controlled clinical trials, uncontrolled observational studies, and case studies were excluded.

Results

A total of 26 RCTs, which included 3,273 participants, met our inclusion criteria. The CAM therapy from the RCTs included the following: mind-body medicine, distant healing, massage, tuina and tai chi, homeopathy, ginseng, and dietary supplementation. Studies of qigong, massage and tuina were demonstrated to have positive effects, whereas distant healing failed to do so. Compared with placebo, homeopathy also had insufficient evidence of symptom improvement in CFS. Seventeen studies tested supplements for CFS. Most of the supplements failed to show beneficial effects for CFS, with the exception of NADH and magnesium.

Conclusions

The results of our systematic review provide limited evidence for the effectiveness of CAM therapy in relieving symptoms of CFS. However, we are not able to draw firm conclusions concerning CAM therapy for CFS due to the limited number of RCTs for each therapy, the small sample size of each study and the high risk of bias in these trials. Further rigorous RCTs that focus on promising CAM therapies are warranted.