Physical and mental fatigue across the menstrual cycle in women with and without generalised anxiety disorder

Subjective, disabling fatigue is a common complaint and a key feature of numerous medical conditions, and is a transdiagnostic feature of psychiatric disorders. Despite physical and mental fatigue being associated with functional impairment and reduced quality of life, little is understood about its underlying mechanisms or modulating factors. Women commonly experience exacerbation of other (non-fatigue related) psychiatric symptoms during the luteal phase of the menstrual cycle, and report greater fatigue prevalence compared to men. It is therefore plausible that subjective fatigue may similarly fluctuate across the menstrual cycle. Here we compared physical and mental fatigue in the early-follicular (lower ovarian hormones) and mid-luteal (higher ovarian hormones) phases of a single menstrual cycle, while controlling for sleep disruption, in women with (n = 18) and without (non-anxious; n = 20) generalised anxiety disorder (GAD). As expected, women with GAD reported greater physical and mental fatigue than healthy women. Further, although there were no changes in physical fatigue from the early-follicular to mid-luteal phases in both groups, mental fatigue in non-anxious women increased to levels equivalent to those experienced by their GAD counterparts in the mid-luteal phase. Although salivary levels of estradiol and progesterone increased from the early-follicular to mid-luteal phase, hormones did not significantly predict fatigue in either phase. These findings are consistent with the exacerbations of state anxiety and mood disturbance recognised to occur in the luteal phase of the menstrual cycle. We speculate that increased mental fatigue in the luteal phase may represent a vulnerable period for the development and maintenance of psychiatric disorders, potentially via compromised emotional regulation.

Effect of estrogen and testosterone replacement therapy on cognitive fatigue

Both estrogen and testosterone insufficiency has been associated with reduced psychological well-being including fatigue. However, hormonal replacement studies on fatigue are rare. Therefore, we wanted to study the effect of testosterone and estrogen replacement therapy on cognitive fatigue and the relation between sex hormone levels and cognitive fatigue in oophorectomized women. Fifty women with surgically induced menopause (mean age: 54.0 ± 2.9 years) were randomly assigned to treatment with estradiol valerate in combination with testosterone undecanoate or placebo for 24 weeks in a double-blind cross-over study. Neuropsychological tests and questionnaires were used to assess cognitive fatigue and psychological well-being. Cognitive fatigue was significantly associated to poor self-rated health and higher body mass index but not to general psychological well-being or sex hormone levels. Treatment with testosterone + estrogen had no significant effect on cognitive fatigue but the results indicated a curvilinear relation for hormonal levels. The estrogen/testosterone ratio was more related to functions rather than high or low hormone levels per se. We found that cognitive fatigue is frequent in oophorectomized women and negatively associated to self-perceived health and positively associated to BMI. A well-balanced ratio between estrogen and testosterone levels may be important for cognitive fatigue.

Effects of a gliadin-combined plant superoxide dismutase extract on self-perceived fatigue in women aged 50-65 years

Fatigue syndromes exist on a continuum of severity from mild and transient to the disabling chronic fatigue syndrome, with oxidative stress linked to its pathogenesis. A thermolabile gliadin-combined plant superoxide dismutase (SOD) extract has shown potential in clinical trials as a therapeutic antioxidant. This study investigated the effects of 12 weeks of 500 mg/day of a SOD/gliadin supplement on fatigue. Thirty-eight women aged 50-65 years with self-perceived fatigue entered this randomized, double-blind, placebo-controlled trial. The primary outcome measure was general fatigue determined by the Multidimensional Fatigue Inventory (MFI). Secondary outcome measures included other measures of fatigue from the MFI and blood measures of oxidative stress, antioxidant status and hormones. There were no significant (P>0.05) differences between, or within groups, for decreases in general fatigue (active=1.6%, placebo=4.1%). There were no within or between group differences (P>0.05) in other measures of fatigue (physical fatigue, reduced activity, reduced motivation, mental fatigue and total fatigue score). In regard to the biochemical measures, there were non-significant (P>0.05) differences in increases in plasma SOD activity (active=7.1%, placebo=12.2%), plasma GPx activity (active=2.4%, placebo=0.7%), red blood cell GPx activity (active=9.8%, placebo=4.4%). Markers of oxidative stress were decreased but there were no differences (P>0.05) within or between groups; malondialdehyde (active=4.1%, placebo=1.6%), F-2 isoprostanes (active=14.7%, placebo=22.4%). There was a trend (P=0.08) for a decrease in cortisol in the active group (24.6%), however this was not significantly different from the decrease in the placebo participants (4.1%). DHEA differences were not significant (P<0.05) and declined 1.3% in the active group and 14.4% in the placebo group. In summary, the thermolabile SOD/gliadin supplement had no significant effect on self-perceived fatigue, antioxidants, oxidative stress or hormones in women aged 50-65 years.

Mental fatigue-induced decrease in levels of several plasma amino acids

To investigate the relation between plasma amino acid levels and mental fatigue, we measured the plasma concentrations of 20 amino acids in 9 healthy volunteers before and after a fatigue-inducing mental task session for 8 hr. As fatigue-inducing mental tasks, the subjects performed an advanced trail making test, a Japanese KANA pick up test, and a mirror drawing test. As a control, 8-hr relaxation session was performed in the same subjects at an interval of 4 weeks. Immediately after the fatigue session, the plasma levels of branched-chain amino acids, tyrosine, cysteine, methionine, lysine, and arginine were below those after a relaxation session. The values for other blood parameters including total protein, albumin, glucose, and total cholesterol did not show any differences between the 2 sessions. These results indicate that mental fatigue may be characterized by a decrease in the plasma level of these amino acids.

Serum cytokine levels related to multiple dimensions of fatigue in patients with primary Sjogren's syndrome

OBJECTIVE

To test whether serum levels of selected cytokines relate to different dimensions of fatigue in patients with primary Sjögren's syndrome (pSS).

METHODS

Sixty female patients with pSS filled out a questionnaire to assess multiple dimensions of fatigue. Scores were compared with values in a population based control group (n = 139). Levels of interleukin (IL)1beta, IL2, IL6, IL10, and tumour necrosis factor alpha were measured in serum with commercial sandwich ELISAs. The relationship between self reported dimensions of fatigue and these serum cytokine levels was determined.

RESULTS

Patients with pSS had high scores at all dimensions of fatigue (p<0.001): general fatigue, physical fatigue, reduced activity, reduced motivation, and mental fatigue. Fatigue levels were not related to serum cytokine levels. The incidental finding that reduced motivation was higher in patients with detectable serum levels of IL10 (p = 0.04) disappeared after correction for multiple testing.

CONCLUSION

Fatigue is prominent in patients with pSS and involves all dimensions of fatigue. The findings do not suggest a widespread effect of circulating cytokines on multiple aspects of fatigue.

Measurement of fatigue in industries

Fatigue of workers is a complex phenomenon resulting from various factors in technically innovated modern industries, and it appears as a feeling of exhaustion, lowering of physiological functions, breakdown of autonomic nervous balance, and decrease in work efficiency. On the other hand industrial fatigue is caused by excessive workload, remarkable alteration in working posture and diurnal and nocturnal rhythms in daily life. Working modes in modern industries have changed from work with the whole body into that with the hands, arms, legs and/or eyes which are parts of the body, and from physical work to mental work. Visual display terminal (VDT) work is one of the most characteristic jobs in the various kinds of workplaces. A large number of fatigue tests have already been adopted, but it is still hard to draw a generalized conclusion as to the method of selecting the most appropriate test battery for a given work load. As apparatus for fatigue measurement of VDT work we have developed VRT (Visual Reaction Test) and the Portable Fatigue Meter. Furthermore, we have presented immune parameters of peripheral blood and splenic T cells for physical fatigue.

Stress hormonal factors, fatigue, and antioxidant responses to prolonged speed driving

Oxygen free radicals have been implicated in exercise-induced cell and tissue injury, indicating an oxidative stress. Fatigue accompanied by a number of physiological and metabolic changes is in indication of overtraining. This study aimed to examine the influence of a continuous 24-h intermittent speed driving (1 h driving/1 h stop), on the response of hormones, antioxidative factors, lipid, and enzyme levels. Seven race car drivers of national level were examined before, during, and immediately after the trial of speed driving on a test designed to check endurance to stress. The parameters measured were: testosterone (Tes), cortisol (Cor), IgM, IgA, cholesterol, HDL, billirubin, ceruloplasmin, urea, uric acid, creatine kinase, and transaminases. Stress hormone Cor declined significantly (p < 0.05), while Tes did not change significantly. Fatigue enzyme, aspartate transaminase (GOT) increased significantly (p < 0.05), while alanine transaminase (GPT) did not change and urea declined. Muscle enzyme, creatine kinase (CK) increased to sixfold (p < 0.01). IgA, IgM and lipids did not change. The primary antioxidant ceruloplasmin increased significantly (p < 0.001), while antioxidants uric acid and glucose remained unchanged. Among the factors measured, ceruloplasmin, cortisol, urea, GOT, and CK seem to give a picture of the organism's alertness and defence capabilities in conditions of stress and fatigue.

Objective evaluation of fatigue by event-related potentials

The purpose of this study was to assess the relationship between mental fatigue and event-related potentials (ERPs). Six healthy men (mean age: 22 years old) performed a simple calculation for 6 h. Auditory ERPs were recorded before and after the calculating task. The scores of subjective fatigue symptoms were significantly increased, and P300 latency of auditory ERPs was significantly prolonged by the calculating task (P<0.05). We suggest that the recording of ERPs may be useful for the objective evaluation of mental fatigue.

Relationship of blood coagulation and fibrinolysis to vital exhaustion

OBJECTIVE

Acute physical and psychological stressors affect blood coagulation and fibrinolysis, but little is known about hemostatic factors associated with chronic psychological stress. Prolonged psychological stress may end in a state of vital exhaustion, which has been shown to be a risk factor for first myocardial infarction and recurrent events after coronary angioplasty. The present study tested the hypothesis that vital exhaustion resulting from chronic psychological stress is associated with impaired fibrinolytic capacity and increased coagulation factors.

METHODS

On the basis of a validated questionnaire and subsequent structured interview, a well-defined group of otherwise healthy exhausted men was recruited (N = 15) and compared with age-matched not-exhausted controls (N = 15). Fibrinolytic measures included tissue plasminogen activator (TPA) antigen and plasminogen activator inhibitor (PAI-1) activity, and as coagulation factors we examined factors VIIc, factor VIIIc, and fibrinogen. Control variables were: blood pressure, smoking status, triglycerides, cholesterol, and standard hematological measures. Samples were collected twice to correct for intraindividual fluctuations. Statistical analyses were performed using 2 x 2 mixed model analysis of variance with subsequent univariate testing.

RESULTS

Vital exhaustion was associated with significantly elevated levels of PAI-1 activity (p = .023). The higher PAI-1 activity in exhausted subjects (median = 13.0 U/ml vs. 6.0 U/ml) was not accounted for by smoking status or serum lipids. No significant differences were observed in TPA antigen, factor VIIc, factor VIIIc, and fibrinogen. The groups did not differ in blood pressure, smoking status, triglycerides, cholesterol, or standard hematological measures.

CONCLUSION

These data suggest a reduced fibrinolytic capacity in exhausted individuals. Therefore, the relationship between vital exhaustion and risk of myocardial infarction may be mediated in part by an imbalance between blood coagulation and fibrinolysis.

Effects of chicken extract on the recovery from fatigue caused by mental workload

Folk wisdom suggests that chicken extract is useful for recovery from physical and mental fatigue. To explore this question, the physiological effect of Brand's Essence of Chicken (BEC), a popular chicken extract used as a traditional remedy, was assessed during recovering from mental stress. We quantitated the blood levels of stress-related substances, and examined the task performance and subjects' mood states during mental workloads. Subjects were 20, healthy male students who have never tasted BEC. They took two bottles of BEC or a placebo (70 ml/bottle) daily in the morning for 7 days. On the final experimental day, two mental workload tests were performed: (A) a mental arithmetic test (MAT; 1600 trials of two or three figure-addition or subtraction for 40 min). (B) a short-term memory test (SMT; 20 trials of memorizing 9 digit numbers). Blood was collected before and after each workload task. After the mental workload, the recovery of mean cortisol level of subjects who consumed BEC was significantly faster than that for those consuming the placebo. The task performance of subjects performing the MAT and SMT was also improved with BEC consumption compared with placebo. According to the profile of mood state questionnaire, subjects felt more active and less fatigued during the workload when they took BEC regularly. We conclude that the extract of chicken has the potential to metabolize stress-related substance in blood and to promote recovery from mental fatigue.

Studies on fatigue of night duty workers at a newspaper office

Fatigue of night duty workers in different divisions of a newspaper office was investigated by physiological methods such as the Blinker, Flicker and grip methods. The relationship between fatigue and hematological parameters such as hemoglobin (Hb), the hematocrit (Ht), serum-free amino acid levels, and indices of liver function such as the GOT and GPT levels were also examined. The composing and press room workers mainly complained of the subjective symptom of muscle fatigue, while workers in the photo-engraving and editorial departments mainly complained of mental fatigue. The overall rate of fatigue in the newspaper office was about 38.1%, but varied from one division to another, being especially high in the photo-engraving and editorial departments. The subjects with fatigue had low levels of serum GOT and GPT and high levels of serum-gluconeogenic amino acids, such as aspartic acid, glutamic acid, prolin, glycine, and alanine. These altered levels of serum-free amino acids and GOT and GPT seemed to be due to increased secretion of adrenal corticoid hormone caused by the stress of fatigue.

Physical and mental fatigue: metabolic mechanisms and importance of plasma amino acids

There are at least 5 metabolic causes of fatigue, a decrease in the phosphocreatine level in muscle, proton accumulation in muscle, depletion of the glycogen store in muscle, hypoglycaemia and an increase in the plasma concentration ratio of free tryptophan/branched-chain amino acids. Proton accumulation may be a common cause of fatigue in most forms of exercise and may be an important factor in fatigue in those persons who are chronically physically inactive and also in the elderly: thus, the aerobic capacity markedly decreases under these conditions, so that ATP must be synthesized by the much less efficient anaerobic system. A marked increase in the plasma fatty acid level, which may occur when liver glycogen store is depleted and when hypoglycaemia results, or during intermittent exercise when the rate of fatty acid oxidation may not match the mobilisation of fatty acids, could be involved indirectly in fatigue. This is because such an increase in the plasma level of fatty acids raises the free plasma concentration of tryptophan, which can increase the entry of tryptophan into the brain, which will increase the brain level of 5-hydroxytryptamine: there is evidence that the latter may be involved in central fatigue. In this case, provision of branched-chain amino acids in order to maintain the resting plasma concentration ratio of free tryptophan/branched-chain amino acids should delay fatigue--there is prima facie evidence in support of this hypothesis. This hypothesis may have considerable clinical importance.

Aerobic fitness and hormonal responses to prolonged sleep deprivation and sustained mental work

This study examined the influence of aerobic fitness on the responses of selected hormones to the combined stressors of sleep deprivation (SD) and sustained mental work. Six aerobically high fit (HF) (VO2max greater than 50 ml.kg-1.min-1) and six average fit (AF) (VO2max less than 40 ml.kg-1.min-1) female subjects were subjected to a period of sleep loss of 60 h during which time they performed sustained mental tasks with no physical activity component. Venous blood samples were drawn every 12 h at 1330 hours and 0130 hours and plasmas analyzed for cortisol, growth hormone (hGH), prolactin, thyroxine (T4), triiodothyronine (T3), and reverse-triiodothyronine (rT3). For cortisol, both the HF and AF groups exhibited the normal high-daytime and low-nighttime pattern of secretion, with levels increasing significantly as the duration of SD increased. The normal elevations of hGH and prolactin levels during normal sleep were suppressed during SD. No significant fitness effects were found for cortisol, hGH, and prolactin responses. Plasma levels of T4, T3, and rT3 increased significantly during SD, with highly fit subjects exhibiting higher levels of these hormones than those of average fitness. We suggest that aerobic fitness may influence the peripheral metabolism of T4 during SD, but that aerobic fitness does not influence the regulation of the classical stress hormones during SD.

Psychobiological effects of carbohydrates

The authors studied whether the fatiguing effects of eating lunch are greater for carbohydrate-rich meals than for other meals, and related the time course of behavioral change to plasma glucose, insulin, and amino acids. On different occasions, in counterbalanced order, normal women (N = 7) fasted overnight, ate a standard breakfast, and at lunch either continued to fast or ate a high-carbohydrate, low-protein meal; a hedonically similar meal containing both carbohydrate and protein; or a high-protein, low-carbohydrate meal. Meals were isocaloric and equated for fat content. Only the carbohydrate meal significantly increased fatigue, which could not be attributed to hypoglycemia because plasma glucose remained elevated. Fatigue began approximately, when the carbohydrate meal elevated the plasma tryptophan ratio but ended even though the ratio remained elevated. Fatigue after a high-carbohydrate lunch could not be explained by reactive hypoglycemia or sweet taste, and could partially be explained by the hypothesis that fatigue parallels an elevation of the tryptophan ratio.