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PubMed2001

Sexual abuse, physical abuse, chronic fatigue, and chronic fatigue syndrome: a community-based study.

Using a randomly selected community-based sample, this investigation examined whether histories of childhood sexual, physical, and death threat abuse predicted adulthood outcomes of specific medical and psychiatric conditions involving chronic fatigue. This study also tested prior suggestions that most individuals with chronic fatigue syndrome report a past history of interpersonal abuse. Multinomial logistic regression was used to examine the relationship between abuse history and chronic fatigue group outcomes while controlling for the effects of sociodemographics. Compared with healthy controls, childhood sexual abuse was significantly more likely to be associated with outcomes of idiopathic chronic fatigue, chronic fatigue explained by a psychiatric condition, and chronic fatigue explained by a medical condition. None of the abuse history types were significant predictors of chronic fatigue syndrome. A closer examination of individuals in the chronic fatigue syndrome group revealed that significantly fewer individuals with CFS reported abuse as compared with those who did not. The implications of these findings are discussed.

Adolescent↗
PubMedDate not supplied

Psychobehavioral and immunological characteristics of adult people with chronic fatigue and patients with chronic fatigue syndrome.

The psychobehavioral responses and cellular immune function were investigated in healthy people (control, N = 21), adult people with chronic fatigue (fatigue-non-CFS group, N = 24), and patients with chronic fatigue syndrome (CFS, N = 10). Based on psychobehavioral responses, the fatigue-non-CFS group had low general activity levels (p < .05) and slightly depressive tendencies (p < .01) compared with the control. They had many life event stresses (p < .05) and sleep disturbances (p < .01), and they could not cope appropriately with stresses. The fatigue-non-CFS group also showed significantly lower natural killer (NK) cell activity (p < .01) and decreased numbers of CD16+ and CD56+ cells (p < .05). Compared with the fatigue-non-CFS group, patients with CFS had higher degrees of physical fatigue (p < .01) and more life event stresses (p < .05). They had lower general activity levels and social introversion. They were also in a depressive state. NK cell activity and the numbers of CD16+ and CD56+ cells were significantly reduced in patients with CFS (p < .01). These findings suggest that adult people with chronic fatigue may be in an intermediate state between the healthy control and patients with CFS in terms of psychobehavioral responses and low NK cell activity. We observed three cases in such an intermediate state in whom CFS subsequently developed.

Adaptation, Psychological↗
PubMed2002

A predictive fatigue model--I: Predicting the effect of stimulation frequency and pattern on fatigue.

Previously we developed a mathematical force- and fatigue-model system that could predict fatigue produced by a wide range of frequencies and pulse patterns. However, the models tended to overestimate the forces produced by higher frequency trains. This paper presents modifications to our previously developed force- and fatigue-model system to improve the accuracy in predicting forces during repetitive activation of human skeletal muscle. By comparing the predictions produced by the modified force and fatigue models to those by our previous models, the modification appears to be successful. The current force- and fatigue-model system accounts for about 93% variance in experimental data produced by fatigue protocols consisting of trains with a wide range of frequencies and pulse patterns. In addition, the present models successfully predict the effect of stimulation frequency and pulse pattern on muscle fatigue. The success of our current force- and fatigue-model system suggests its potential use in helping to identify the optimal activation pattern to use during the clinical application of functional electrical stimulation.

Algorithms↗
PubMed2002

Analysis of 16S rRNA gene sequences and circulating cell-free DNA from plasma of chronic fatigue syndrome and non-fatigued subjects.

BACKGROUND: The association of an infectious agent with chronic fatigue syndrome (CFS) has been difficult and is further complicated by the lack of a known lesion or diseased tissue. Cell-free plasma DNA could serve as a sentinel of infection and disease occurring throughout the body. This type of systemic sample coupled with broad-range amplification of bacterial sequences was used to determine whether a bacterial pathogen was associated with CFS. Plasma DNA from 34 CFS and 55 non-fatigued subjects was assessed to determine plasma DNA concentration and the presence of bacterial 16S ribosomal DNA (rDNA) sequences. RESULTS: DNA was isolated from 81 (91%) of 89 plasma samples. The 55 non-fatigued subjects had higher plasma DNA concentrations than those with CFS (average 151 versus 91 ng) and more CFS subjects (6/34, 18%) had no detectable plasma DNA than non-fatigued subjects (2/55, 4%), but these differences were not significant. Bacterial sequences were detected in 23 (26%) of 89. Only 4 (14%) CFS subjects had 16S rDNA sequences amplified from plasma compared with 17 (32%) of the non-fatigued (P = 0.03). All but 1 of the 23 16S rDNA amplicon-positive subjects had five or more unique sequences present. CONCLUSIONS: CFS subjects had slightly lower concentrations or no detectable plasma DNA than non-fatigued subjects. There was a diverse array of 16S rDNA sequences in plasma DNA from both CFS and non-fatigued subjects. There were no unique, previously uncharacterized or predominant 16S rDNA sequences in either CFS or non-fatigued subjects.

DNA↗
PubMed2004

Mechanisms underlying fatigue: a voxel-based morphometric study of chronic fatigue syndrome.

BACKGROUND: Fatigue is a crucial sensation that triggers rest, yet its underlying neuronal mechanisms remain unclear. Intense long-term fatigue is a symptom of chronic fatigue syndrome, which is used as a model to study the mechanisms underlying fatigue. METHODS: Using magnetic resonance imaging, we conducted voxel-based morphometry of 16 patients and 49 age-matched healthy control subjects. RESULTS: We found that patients with chronic fatigue syndrome had reduced gray-matter volume in the bilateral prefrontal cortex. Within these areas, the volume reduction in the right prefrontal cortex paralleled the severity of the fatigue of the subjects. CONCLUSION: These results are consistent with previous reports of an abnormal distribution of acetyl-L-carnitine uptake, which is one of the biochemical markers of chronic fatigue syndrome, in the prefrontal cortex. Thus, the prefrontal cortex might be an important element of the neural system that regulates sensations of fatigue.

Adult↗
PubMed2004

Fatigue and its underlying factors among elderly citrus farmers in a rural area of Japan--effect of social support on fatigue and gender difference.

The purposes of this study were to assess fatigue among elderly citrus farmers and indicating countermeasures to reduce the workload of agricultural work and the work-related stress among elderly citrus farmers. The Fatigue Questionnaire for Farmers developed by the Rural Life Research Institute, Japan was used after a modification by the addition of items related to dietary life. It was found that some of the factors causing fatigue among citrus farmers differed between men and women. There was a clear correlation between agricultural work load and the severity of fatigue. Among these elderly farmers, the qualitative aspect of work stress had much more effect on fatigue than the quantitative aspect. And, the fact that social support impossibility for them deepened their sense of dissatisfaction with work and social life indicated the importance of social support for them. The study suggested that the modified questionnaire was shown to be useful in the assessment of fatigue among agricultural workers; however, it needs to be simplified. Further study using the simplified fatigue questionnaire is needed for further clarification of fatigue and its underlying factors among agricultural workers.

Adult↗
PubMed1988

The frequency of the chronic fatigue syndrome in patients with symptoms of persistent fatigue.

STUDY OBJECTIVE: To determine the frequency of the chronic fatigue syndrome among patients with symptoms of fatigue. DESIGN: Prospective, cohort study. SETTING: Referral clinic, based in a primary care general internal medicine faculty practice of a university medical center. PATIENTS: Consecutive sample of 135 patients (53 men, 82 women) with 6 months or more of debilitating fatigue. INTERVENTIONS: All patients had a complete history taken, had a physical examination and a comprehensive battery of blood tests, and were given the Diagnostic Interview Schedule of the National Institute of Mental Health, a highly-structured 260-item instrument designed to enable accurate psychiatric diagnoses. Other diagnostic studies (for example, sleep studies and electroencephalography) were ordered if necessary for individual patients. MEASUREMENTS AND MAIN RESULTS: Six of the one hundred thirty-five patients met criteria for chronic fatigue syndrome (95% CI, 0 to 10). Ninety-one (67%) patients (CI, 56 to 78) had clinically active psychiatric disorders and 4 (3%) patients (CI, 0 to 8) had medical disorders that were considered a major cause of their fatigue. Thirty-four (25%) patients (CI, 14 to 36) had insufficient symptoms or objective findings of the chronic fatigue syndrome. CONCLUSION: The chronic fatigue syndrome is rare among patients with symptoms of persistent fatigue. Most of these patients have psychiatric disorders.

Adult↗
PubMed1999

Different effects of verapamil and low calcium on repetitive contractile activity of frog fatigue-resistant and easily-fatigued muscle fibres.

The effects of low calcium and verapamil on contractility of two muscle fibre types (m. iliofibularis, Rana temporaria) upon different stimulation protocols were been compared. Verapamil (0.02 mmol/l) induced temporal excitation-contraction coupling failure during single tetanic stimulation and enhanced the decline of tetanic force during 30 s repetitive tetanic stimulation in both fatigue-resistant fibres and easily-fatigued fibres. In contrast to verapamil, low extracellular calcium (0.02 mmol/l) only enhanced the decline of tetanic force in fatigue-resistant during repetitive tetanic stimulation but had no effect on easily-fatigued fibres. The effect of verapamil on the decline of tetanic force in fatigue-resistant fibres was more profound in low calcium conditions. Both verapamil and low calcium eliminated twitch facilitation that appeared after prolonged contractile activity in fatigue-resistant fibres. 4mmol/l Ni+2, used as calcium channel antagonist, had effects similar to low calcium medium. It could be concluded that (i) extracellular Ca2+-requirements for excitation-contraction coupling are different in fatigue-resistant and easily-fatigued fibres; (ii) the effects of verapamil on force performance are not entirely dependent upon calcium channel blockade.

Animals↗
PubMed2003

[Neural and molecular mechanisms of fatigue and recovery from fatigue].

Fatigue is an indispensable biosignal for maintaining life. However, the neural/molecular mechanisms of fatigue are still unclear. Here, the recent progress in this field is introduced, mostly through our project research under the control of the Ministry of Education, Culture, Sports, Science and Technology (MEXT), Japanese Government. The sensing mechanisms of fatigue in the brain might be related to the orbitofrontal-dorsoprefrontal-cingulate triangle circuits. We hypothesized the neural circuits for fatigue sensation through our PET study on chronic fatigue patients and healthy volunteers. The serotonergic system might be involved in the sensation in the prefrontal cortex, although the hyperserotonin hypothesis might be wrong. The fatigue sensation is somehow related to hypofunction of the glutamatergic system through reduced uptake of acetyl-carnitine in the discrete brain regions. For creation of new methods and drugs overcoming fatigue, different types of animal models of fatigue were developed. By using such animal models, the green leaf odor, ascorbic acid, acetyl-carnitine, and tetrahydrobiopterin have been found to be effective.

Acetylcarnitine↗
PubMed1986

[Fatigue in women conducting work with predominantly dynamic effort. I. Work demands and type of signs of fatigue].

In evaluation of fatigue by the working day and evaluation of chronic fatigue subjective methods have been applied. The fatigue due to the working day was tested twice during a work shift--in the 2nd and 8th working hour. Two professional groups of women were covered by the investigation: knitters (94) and sorters (44). It was a sufficient sample. The fatigue was found to be relatively low--it did not surpass the value of 2 points. Only some symptoms occurred with greater intensity, e.g. tiredness of legs and whole body. This results from the type of work performed by the women. The correlation between the type of fatigue symptoms and type of work is also confirmed by differences in evaluation of knitters and sorters. The evaluation of fatigue in both professional groups did not differ from the results of studies of the fatigue after the working day. Only somatic disturbances were evaluated higher; the differences between sorters and knitters in this group of symptoms possibly being affected by the differences in the workers' age. The obtained results indicate that despite the differences in the type of work, the type and magnitude of fatigue were similar at both workplaces.

Adult↗
PubMed2007

Bone formation after damaging in vivo fatigue loading results in recovery of whole-bone monotonic strength and increased fatigue life.

Bone has a remarkable capacity for self-repair. We previously reported a woven bone response after damaging in vivo fatigue loading of the rat ulna that led to a rapid recovery of whole-bone strength. In the current study we asked: does the bone response in the 12 days after damaging fatigue loading result in a bone that has normal fatigue properties? The right forelimbs of 52 adult rats were subjected to a single bout of in vivo fatigue loading. Nonloaded left forelimbs were used as controls. Ulnar geometric properties were assessed by peripheral quantitative computed tomography (pQCT) and ex vivo mechanical properties were assessed by three-point bending. On day 0, ulnae from loaded forelimbs had a 15-20% reduction in stiffness and ultimate force versus controls (p < 0.10), indicative of structural damage. On day 12, bone area at the midshaft was increased by 27% (p < 0.001) and microCT scans revealed periosteal woven bone at this site. This bone response led to a recovery of the monotonic properties of loaded ulnae at day 12 versus control (stiffness, p = 0.73; ultimate force, p = 0.96). Importantly, fatigue testing ex vivo at day 12 demonstrated significantly greater fatigue life in in vivo loaded ulnae versus controls (p < 0.001). Additionally, the slope of the fatigue-life curve was significantly less in loaded versus control ulnae (p < 0.002). We conclude that woven bone "repair" of a bone damaged by fatigue loading restores whole-bone strength and enhances resistance to further damage by repetitive loading.

Animals↗
PubMed2000

On fatigue lifetimes and fatigue crack growth behavior of bone cement.

Bone cement is used to develop a mechanical bond between an artificial joint and the adjacent bone tissue, and any degradation of this bond is of serious concern since it can lead to loosening and eventually malfunction of the artificial joint. In the present study, the fatigue lives and fatigue crack propagation behavior of two bone cements, CMW Type 3 and Zimmer, were investigated, and it was found that the size and distribution of pores played a major role in influencing both the fatigue crack initiation and propagation processes. The fatigue lifetimes of CMW exceeded those of Zimmer because of a lesser density of large pores. When the fatigue lifetimes were plotted as a function of Klimax, the maximum initial stress intensity factor based upon the initiating pore size, the difference in fatigue lifetimes between CMW and Zimmer bone cements was greatly reduced. The fatigue crack growth behavior of both bone cements were similar. This is a further indication that the noted differences in fatigue lifetimes were related to the size of the pore at the crack initiating site.

Journal Article↗
PubMed1994

Quadriceps femoris muscle resistance to fatigue using an electrically elicited fatigue test following intense endurance exercise training.

BACKGROUND AND PURPOSE: Electrical stimulation has been used to assess skeletal muscle resistance to fatigue. The purpose of this study was to test the hypothesis that 12 weeks of intense endurance exercise training on a bicycle ergometer would reduce the percentage of decline in quadriceps femoris muscle torque during an electrically elicited fatigue test. SUBJECTS AND METHODS: Eleven nondisabled subjects performed 12 weeks of high-intensity endurance exercise training, and 6 subjects served as controls and did not exercise. Two electrically elicited fatigue tests, one with and one without prior voluntary fatiguing exercise, were administered to each subject before and after the 12-week training period. RESULTS: The percentage of decline in peak torque of the quadriceps femoris muscle over 50 electrically elicited muscle contractions did not change as a result of endurance exercise training, despite significant improvements in maximal oxygen consumption and quadriceps femoris muscle endurance. The recovery of maximal isometric torque immediately after exhausting voluntary exercise followed by electrical stimulation was significantly greater after 12 weeks of intense exercise training. CONCLUSION AND DISCUSSION: The percentage of decline in peak torque during an electrically elicited fatigue test does not detect improvements in quadriceps femoris muscle endurance induced by endurance exercise training. The percentage of initial torque recovered immediately after fatiguing exercise, however, is improved by endurance training. [Sinacore Dr, Jacobson RB, Delitto A. Quadriceps femoris muscle resistance to fatigue using an electrically elicited fatigue test following intense endurance exercise training.

Adult↗
PubMed1997

The effects of fatigue on neuropsychological performance in patients with chronic fatigue syndrome, multiple sclerosis, and depression.

The effects of fatigue on neuropsychological performance were examined in patients with fatiguing illnesses. Repeated testing with the Paced Auditory Serial Addition Test (PASAT; Gronwall, 1977) was employed over the course of a demanding neuropsychological testing session. It was hypothesized that if fatigue affects performance, one would expect to observe "blunting" of the PASAT practice effect. Fifteen of the study participants live with chronic fatigue syndrome (CFS), 15 with multiple sclerosis (MS), 14 with depression (DEP), and 15 are healthy, sedentary controls. Overall PASAT performance was significantly reduced for CFS and DEP participants compared to controls, whereas mean performance did not differ across the three fatiguing illness groups. Degree of improvement across trials (i.e., practice effect) for the groups did not differ from controls'. Neither subjective fatigue or DEP were significantly related to PASAT performance. These findings suggest that fatigue does not universally impair performance during neuropsychological assessment even in groups in which fatigue is a prominent symptom.

Journal Article↗
PubMed1993

Chronic fatigue and chronic fatigue syndrome: clinical epidemiology and aetiological classification.

To determine the medical and psychiatric diagnoses that have an aetiological role in chronic fatigue we conducted a prospective study of 405 (65% women) patients who presented for evaluation with this chief complaint to an academic medical centre. The average age was 38.1 years and the average duration of fatigue at entry in the study was 6.9 years. All patients were given comprehensive physical and laboratory evaluations and were administered a highly structured psychiatric interview. Psychiatric diagnoses explaining the chronic fatigue were identified in 74% of patients and physical disorders were diagnosed in 7% of patients. The most common psychiatric conditions in this series were major depression, diagnosed in 58% of patients, panic disorder, diagnosed in 14% of patients, and somatization disorder, diagnosed in 10% of patients. Primary sleep disorders, diagnosed in 2% patients, and chronic infections, confirmed in 1.6% patients, explained the majority of cases whose chronic fatigue was attributed to a physical disorder. Thirty per cent of patients met the criteria used to define the chronic fatigue syndrome (CFS). Compared with age- and gender-matched control subjects with chronic fatigue, CFS patients had a similarly high prevalence of current psychiatric disorders (78% versus 82%), but were significantly more likely to have somatization disorder (28% versus 5%) and to attribute their illness to a viral infection (70% versus 33%). We conclude that most patients with a chief complaint of chronic fatigue, including those exhibiting the features of CFS, suffer from standard mood, anxiety and/or somatoform disorders. Careful research is still needed to determine whether CFS is a distinct entity or a variant of these psychiatric illness.

Adult↗
PubMed1998

Parallels between post-polio fatigue and chronic fatigue syndrome: a common pathophysiology?

Fatigue is the most commonly reported and most debilitating of post-polio sequelae affecting the >1.8 million North American polio survivors. Post-polio fatigue is characterized by subjective reports of difficulty with attention, cognition, and maintaining wakefulness. These symptoms resemble those reported in nearly 2 dozen outbreaks of post-viral fatigue syndromes (PVFS) that have recurred during this century and that are related clinically, historically, anatomically, or physiologically to poliovirus infections. This article reviews recent studies that relate the symptoms of post-polio fatigue and chronic fatigue syndrome (CFS) to clinically significant deficits on neuropsychologic tests of attention, histopathologic and neuroradiologic evidence of brain lesions, impaired activation of the hypothalamic-pituitary-adrenal axis, increased prolactin secretion, and electroencephalogram (EEG) slow-wave activity. A possible common pathophysiology for post-polio fatigue and CFS, based on the Brain Fatigue Generator Model of PVFS, and a possible pharmacotherapy for PVFS based on replacement of depleted brain dopamine, will be described.

Adult↗
PubMed1997

The prognosis of chronic fatigue and chronic fatigue syndrome: a systematic review.

The prognosis of chronic fatigue syndrome and chronic fatigue has been studied in numerous small case series. We performed a systematic review of all studies to determine the proportion of individuals with the conditions who recovered at follow-up, the risk of developing alternative physical diagnoses, and the risk factors for poor prognosis. A literature search of all published studies which included a follow-up of patients with chronic fatigue syndrome or chronic fatigue were performed. Of 26 studies identified, four studied fatigue in children, and found that 54-94% of children recovered over the periods of follow-up. Another five studies operationally defined chronic fatigue syndrome in adults and found that < 10% of subjects return to pre-morbid levels of functioning, and the majority remain significantly impaired. The remaining studies used less stringent criteria to define their cohorts. Among patients in primary care with fatigue lasting < 6 months, at least 40% of patients improved. As the definition becomes more stringent the prognosis appears to worsen. Consistently reported risk factors for poor prognosis are older age, more chronic illness, having a comorbid psychiatric disorder and holding a belief that the illness is due to physical causes.

Adult↗
PubMed1991

Human quadriceps strength and fatiguability in patients with post viral fatigue.

Quadriceps isometric strength, activation and fatiguability were measured in 11 patients with symptoms of fatigue three months after glandular fever or a glandular fever-like illness. Predicted normal and lower limits of normal muscle strength were calculated from height and age. These measures and the fatigue index were compared with a group of healthy students of similar age. Two of the patients were unable to activate fully their muscles. After allowing for this inhibition the group mean (SD) strength was 104 (22%) of predicted. Although there was no significant difference in the fatigue index between the patients and the control group, there was a trend for the patients to show less fatigue than controls. There was no difference in the muscle results for those patients who were found to have Epstein-Barr virus infections and those who did not. The feelings of weakness and fatigue experienced by the patients could not be explained by either physiological muscle fatigue or lack of effort.

Adolescent↗