Salivary cortisol as a predictor of postoperative fatigue

A rapid, non-invasive method for fatigue detection based on voice information

Fatigue results from a series of physiological and psychological changes due to continuous energy consumption. It can affect the physiological states of operators, thereby reducing their labor capacity. Fatigue can also reduce efficiency and, in serious cases, cause severe accidents. In addition, it can trigger pathological-related changes. By establishing appropriate methods to closely monitor the fatigue status of personnel and relieve the fatigue on time, operation-related injuries can be reduced. Existing fatigue detection methods mostly include subjective methods, such as fatigue scales, or those involving the use of professional instruments, which are more demanding for operators and cannot detect fatigue levels in real time. Speech contains information that can be used as acoustic biomarkers to monitor physiological and psychological statuses. In this study, we constructed a fatigue model based on the method of sleep deprivation by collecting various physiological indexes, such as P300 and glucocorticoid level in saliva, as well as fatigue questionnaires filled by 15 participants under different fatigue procedures and graded the fatigue levels accordingly. We then extracted the speech features at different instances and constructed a model to match the speech features and the degree of fatigue using a machine learning algorithm. Thus, we established a method to rapidly judge the degree of fatigue based on speech. The accuracy of the judgment based on unitary voice could reach 94%, whereas that based on long speech could reach 81%. Our fatigue detection method based on acoustic information can easily and rapidly determine the fatigue levels of the participants. This method can operate in real time and is non-invasive and efficient. Moreover, it can be combined with the advantages of information technology and big data to expand its applicability.

Surgical resilience: a review of resilience biomarkers and surgical recovery

BACKGROUND

Two distinct and large bodies of literature exist on resilience that are of potential interest for surgical outcomes. First is the literature on the impact of resilience on surgical recovery and wound-healing. Second is the literature on biomarkers for resilience, which largely focuses on neuropeptide Y (NPY), testosterone and dehydroepiandrosterone (DHEA). Despite this activity, there is a dearth of literature linking these two bodies of research by investigating biomarkers for surgical resilience and its impact on surgical recovery. This paper reviews both bodies of literature within the context of surgical recovery.

METHOD

Literature searches within Medline and Embase were conducted for studies and previous reviews of resilience biomarkers and for the impact of individual resilience on surgical recovery. Reference lists of the reviews were searched for additional papers. No systematic review is yet possible due to the novelty of the use of resilience biomarkers within a surgical context.

RESULTS

This is the first review to explore a potential link between resilience biomarkers and surgical recovery. There are a number of biomarkers that correlate with individual resilience levels and resilient individuals exhibit better recovery trajectories following surgery, suggesting a novel use of such biomarkers for the identification of "surgical resilience".

CONCLUSION

By identifying surgical resilience, there is potential for utilising these biomarkers as prognostic indicators of likely recovery trajectories from surgery, which in turn complement individualised peri-operative management.

Stress management skills, neuroimmune processes and fatigue levels in persons with chronic fatigue syndrome

OBJECTIVES

Stressors and emotional distress responses impact chronic fatigue syndrome (CFS) symptoms, including fatigue. Having better stress management skills might mitigate fatigue by decreasing emotional distress. Because CFS patients comprise a heterogeneous population, we hypothesized that the role of stress management skills in decreasing fatigue may be most pronounced in the subgroup manifesting the greatest neuroimmune dysfunction.

METHODS

In total, 117 individuals with CFS provided blood and saliva samples, and self-report measures of emotional distress, perceived stress management skills (PSMS), and fatigue. Plasma interleukin-1-beta (IL-1β, IL-2, IL-6, IL-10, and tumor necrosis factor-alpha (TNF-α), and diurnal salivary cortisol were analyzed. We examined relations among PSMS, emotional distress, and fatigue in CFS patients who did and did not evidence neuroimmune abnormalities.

RESULTS

Having greater PSMS related to less fatigue (p=.019) and emotional distress (p<.001), greater diurnal cortisol slope (p=.023) and lower IL-2 levels (p=.043). PSMS and emotional distress related to fatigue levels most strongly in CFS patients in the top tercile of IL-6, and emotional distress mediated the relationship between PSMS and fatigue most strongly in patients with the greatest circulating levels of IL-6 and a greater inflammatory (IL-6):anti-inflammatory (IL-10) cytokine ratio.

DISCUSSION

CFS patients having greater PSMS show less emotional distress and fatigue, and the influence of stress management skills on distress and fatigue appear greatest among patients who have elevated IL-6 levels. These findings support the need for research examining the impact of stress management interventions in subgroups of CFS patients showing neuroimmune dysfunction.

Effects on postoperative salivary cortisol of relaxation/music and patient teaching about pain management

The physiological and psychological stress of surgery and postoperative pain can leave patients more susceptible to infection and complications. The present study was designed to determine whether two interventions, patient teaching (PT) for pain management and relaxation/music (RM), reduced cortisol levels, an indicator of stress, following abdominal surgery. Patients (18-75 years) were randomly assigned to receive PT, RM, a combination of the two, or usual care; the 205 patients with both pre- and posttest cortisol values were analyzed. A 2 × 2 factorial design was used to compare groups for PT effects and RM effects. Stress was measured by salivary cortisol before and after 20-min tests of the interventions in the morning and afternoon of postoperative Day 2. Saliva was stimulated with lemon juice and analyzed with high-sensitivity salivary cortisol enzyme immunoassay. Comparisons using analysis of covariance (ANCOVA), controlling for baseline levels, showed no PT effect or RM effect on cortisol in the morning or afternoon. Post hoc ANCOVA showed no significant effects when intervention groups were compared to the control group. Although in previous studies, RM reduced pain and music reduced cortisol on Day 1, in the present study the cortisol response to surgery was not attenuated by PT or RM on Day 2. The RM intervention can be used for pain but needs to be further tested for effects on plasma cortisol in abdominal surgery patients on their first postoperative day.

Hypothalamic-pituitary-adrenal axis dysfunction in chronic fatigue syndrome

The weight of current evidence supports the presence of the following factors related to hypothalamic-pituitary-adrenal (HPA) axis dysfunction in patients with chronic fatigue syndrome (CFS): mild hypocortisolism; attenuated diurnal variation of cortisol; enhanced negative feedback to the HPA axis; and blunted HPA axis responsiveness. Furthermore, HPA axis changes seem clinically relevant, as they are associated with worse symptoms and/or disability and with poorer outcomes to standard treatments for CFS. Regarding etiology, women with CFS are more likely to have reduced cortisol levels. Studies published in the past 8 years provide further support for a multifactorial model in which several factors interact to moderate HPA axis changes. In particular, low activity levels, depression and early-life stress appear to reduce cortisol levels, whereas the use of psychotropic medication can increase cortisol. Addressing these factors-for example, with cognitive behavioral therapy-can increase cortisol levels and is probably the first-line approach for correcting HPA axis dysfunction at present, as steroid replacement is not recommended. Given what is now a fairly consistent pattern of findings for the type of HPA axis changes found in CFS, we recommend that future work focuses on improving our understanding of the cause and relevance of these observed changes.

Dysfunction of stress responsive systems as a risk factor for functional somatic syndromes

The etiology of functional somatic syndromes or disorders (FSDs) is generally considered to be a multifactorial interplay between psychological, biological, and social factors. One of the most investigated biological factors is stress responsive system dysfunction. Despite more than twenty years of research of the autonomic nervous system and the hypothalamic-pituitary-adrenal axis, however, it is yet unknown whether dysfunctions in these systems play a causal role in the etiology of FSDs and whether they are generic or FSD-specific. In this review, we will give an overview of available evidence on whether or not alterations in these stress responsive systems can be considered causal risk factors of FSDs. We conclude that although not necessary factors for FSDs in general, lowered cardiac vagal activity and hypocortisolism may be pivotal in the etiology and treatment strategy in subgroups of subjects with a FSD. Such subgroups need to be better identified.

Dysfunction of the hypothalamic-pituitary-adrenal axis and functional somatic symptoms: a longitudinal cohort study in the general population

In persons with functional somatic symptoms (FSS), no conventionally defined organic pathology is apparent. It has been suggested that complex interactions of psychological, physiological, and social factors are involved in the etiology of FSS. One of the physiological mechanisms that may contribute to FSS is the function of the hypothalamic-pituitary-adrenal (HPA)-axis. This study investigates the association of HPA-axis function with cross-sectional presence and prospective development of FSS in the general population. This study was performed in a population-based cohort of 741 male and female adults (mean age 53.1, S.D. 10.9). Participants completed the somatization section of the Composite International Diagnostic Interview (CIDI) in which the presence of 43 FSS is surveyed. In addition to the total number of FSS, bodily system FSS clusters with musculoskeletal, gastrointestinal, cardiorespiratory, and general symptoms were constructed. HPA-axis function was assessed by measuring 24-h urinary free cortisol (24-h UFC) excretion. Follow-up measurements were performed approximately 2 years later. All analyses were adjusted for age, gender, body mass index, smoking, alcohol use, depression, exercise frequency, and urinary volume. Regression analysis detected no cross-sectional association between 24-h UFC excretion and the number of FSS (beta=-0.021, t=-0.521, p=0.603). In addition, 24-h UFC excretion was not associated with any of the bodily system FSS clusters (all p>0.050). Furthermore, 24-h UFC excretion did not predict new-onset FSS in the 2-year follow-up period (beta=0.021, t=0.566, p=0.572). We conclude that this study does not provide evidence for an association between altered HPA-axis function, as indexed by 24-h UFC, and FSS in the general population. We conclude that this study does not provide evidence for an association between altered HPA-axis function, as indexed by 24-h UFC, and FSS in the general population.

Salivary cortisol output before and after cognitive behavioural therapy for chronic fatigue syndrome

BACKGROUND

There is evidence that patients with chronic fatigue syndrome (CFS) have mild hypocortisolism. One theory about the aetiology of this hypocortisolism is that it occurs late in the course of CFS via factors such as inactivity, sleep disturbance, chronic stress and deconditioning. We aimed to determine whether therapy aimed at reversing these factors--cognitive behavioural therapy for CFS--could increase cortisol output in CFS.

METHODS

We measured diurnal salivary cortisol output between 0800 and 2000 h before and after 15 sessions (or 6 months) of CBT in 41 patients with CDC-defined CFS attending a specialist, tertiary outpatient clinic.

RESULTS

There was a significant clinical response to CBT, and a significant rise in salivary cortisol output after CBT.

LIMITATIONS

We were unable to control for the passage of time using a non-treated CFS group.

CONCLUSIONS

Hypocortisolism in CFS is potentially reversible by CBT. Given previous suggestions that lowered cortisol may be a maintaining factor in CFS, CBT offers a potential way to address this.

Does hypothalamic-pituitary-adrenal axis hypofunction in chronic fatigue syndrome reflect a 'crash' in the stress system?

The etiopathogenesis of chronic fatigue syndrome (CFS) remains poorly understood. Although neuroendocrine disturbances - and hypothalamic-pituitary-adrenal (HPA) axis hypofunction in particular - have been found in a large proportion of CFS patients, it is not clear whether these disturbances are cause or consequence of the illness. After a review of the available evidence we hypothesize that that HPA axis hypofunction in CFS, conceptualized within a system-biological perspective, primarily reflects a fundamental and persistent dysregulation of the neurobiological stress system. As a result, a disturbed balance between glucocorticoid and inflammatory signaling pathways may give rise to a pathological cytokine-induced sickness response that may be the final common pathway underlying central CFS symptoms, i.e. effort/stress intolerance and pain hypersensitivity. This comprehensive hypothesis on HPA axis hypofunction in CFS may stimulate diagnostic refinement of the illness, inform treatment approaches and suggest directions for future research, particularly focusing on the neuroendocrine-immune interface and possible links between CFS, early and recent life stress, and depression.

Glucocorticoid receptor mediated negative feedback in chronic fatigue syndrome using the low dose (0.5 mg) dexamethasone suppression test

BACKGROUND

Chronic fatigue syndrome (CFS) is associated with hypocortisolism, but it is not yet clear the extent to which enhanced negative feedback may underlie this finding.

METHODS

We undertook a low-dose dexamethasone (0.5 mg) suppression test in 18 CFS patients and 20 matched, healthy controls. We measured salivary cortisol levels at 0800 h, 1200 h, 1600 h and 2000 h before and after the administration of 0.5 mg of dexamethasone.

RESULTS

Basal cortisol output was raised in this group of CFS patients compared to controls. Overall, the percentage suppression following dexamethasone administration was no different between CFS (mean+/-sem: 80.4+/-4.4%) and controls (76.2+/-4.9 %). However, the sub-group of patients with CFS and comorbid depression (n=9) showed a significant hypersuppression of salivary cortisol in response to dexamethasone (89.0+/-1.9%; p<0.05 v controls).

LIMITATIONS

The sub-group analysis was on small numbers and should be considered preliminary. Dexamethasone probes only glucocorticoid medicated negative feedback but does not probe mineralocorticoid feedback, the other main physiological feedback mechanism.

CONCLUSION

We found partial support for the hypothesis of enhanced negative feedback in CFS but only in patients with comorbid depression and also in the context of a sample of patients with elevated basal cortisol levels, which is an atypical finding in the literature.

Relationships between fatigue and early postoperative recovery outcomes over time in elderly patients undergoing coronary artery bypass graft surgery

BACKGROUND

Despite successful coronary artery bypass graft (CABG) surgery, some patients continue to experience fatigue after their surgery.

OBJECTIVE

The purpose of this secondary analysis study was to examine the relationships of fatigue and early recovery outcomes (psychosocial and physiologic functioning, and physical activity) over time (6 weeks and 3 months) among older adult subjects, age 65 years and older, after CABG surgery. Comparison groups were those subjects who had fatigue at 3 weeks after surgery and nonfatigued subjects.

DESIGN

A prospective, comparative design was used for this secondary analysis study.

SAMPLE

Subjects in this study were drawn from the control group of subjects enrolled in the larger parent study. Subjects (N = 119) were dichotomized into fatigue (n = 66) and nonfatigued (n = 53) groups on the basis of their 3-week self-reports of postoperative fatigue.

RESULTS

At 6 weeks after surgery, fatigued subjects had significantly (P < .05) more impaired psychosocial functioning (role-emotional [t = 1.9], social [t = 2.6], and mental [t = 1.9] functioning) on the basis of the Medical Outcome Study Short Form 36. They had significantly (P < .005) higher mean hospital anxiety (t = -3.6) and depression (t = -2.9) subscale scores, respectively. Anxiety (t = -2.3, P < .05) remained significantly (P < .05) impaired at 3 months. At 6 weeks, role physical functioning, measured by the Medical Outcome Study Short Form 36, was significantly impaired (t = 2.4, P < .01). There were no significant differences in physical activity variables as measured by an RT3 accelerometer (Stayhealthy, Inc., Monrovia, CA) and self-report diary.

CONCLUSIONS

Persistent fatigue can hamper early recovery after CABG surgery. Tailored interventions are needed to address fatigue management and improve patient outcomes.

The associations between basal salivary cortisol and illness symptomatology in chronic fatigue syndrome

Hypocortisolism has been reported in chronic fatigue syndrome (CFS), with the significance of this finding to disease etiology unclear. This study examined cortisol levels and their relationships with symptoms in a group of 108 individuals with CFS. CFS symptoms examined included fatigue, pain, sleep difficulties, neurocognitive functioning, and psychiatric status. Alterations in cortisol levels were examined by calculation of mean daily cortisol, while temporal variation in cortisol function was examined by means of a regression slope. Additionally, deviation from expected cortisol diurnal pattern was determined via clinical judgment. Results indicated that fatigue and pain were associated with salivary cortisol levels. In particular, variance from the expected pattern of cortisol was associated with increased levels of fatigue. The implications of these findings are discussed.

Alterations in diurnal salivary cortisol rhythm in a population-based sample of cases with chronic fatigue syndrome

OBJECTIVE

To examine diurnal salivary cortisol rhythms and plasma IL-6 concentrations in persons with chronic fatigue syndrome (CFS), persons not fulfilling a diagnosis of CFS (we term them cases with insufficient symptoms or fatigue, ISF) and nonfatigued controls (NF). Previous studies of CFS patients have implicated the hypothalamic-pituitary-adrenal axis and the immune system in the pathophysiology of CFS, although results have been equivocal.

METHODS

Twenty-eight people with CFS, 35 persons with ISF, and 39 NF identified from the general population of Wichita, Kansas, were admitted to a research ward for 2 days. Saliva was collected immediately on awakening (6:30 AM), at 08:00 AM, 12 noon, 4:00 PM, 8:00 PM and at bedtime (10:00 PM) and plasma was obtained at 7:30 AM. Salivary cortisol concentrations were assessed using radioimmunoassay, and plasma IL-6 was measured using sandwich enzyme-linked immunosorbent assay.

RESULTS

People with CFS demonstrated lower salivary cortisol concentrations in the morning and higher salivary cortisol concentrations in the evening compared with both ISF and NF groups indicating a flattening of the diurnal cortisol profile. Mean plasma IL-6 concentrations were highest in CFS compared with the other groups, although these differences were no longer significant after controlling for BMI. Attenuated decline of salivary cortisol concentrations across the day and IL-6 concentration were associated with fatigue symptoms in CFS.

CONCLUSIONS

These results suggest an altered diurnal cortisol rhythm and IL-6 concentrations in CFS cases identified from a population-based sample.

The hypothalamo-pituitary-adrenal axis in chronic fatigue syndrome and fibromyalgia syndrome

The hypothalamo-pituitary-adrenal (HPA) axis plays a major role in the regulation of responses to stress. Human stress-related disorders such as chronic fatigue syndrome (CFS), fibromyalgia syndrome (FMS), chronic pelvic pain and post-traumatic stress disorder are characterized by alterations in HPA axis activity. However, the role of the HPA axis alterations in these stress-related disorders is not clear. Most studies have shown that the HPA axis is underactive in the stress-related disorders, but contradictory results have also been reported, which may be due to the patients selected for the study, the methods used for the investigation of the HPA axis, the stage of the syndrome when the tests have been done and the interpretation of the results. There is no structural abnormality in the endocrine organs which comprise the HPA axis, thus it seems that hypocortisolemia found in the patients with stress-related disorder is functional. It may be also an adaptive response of the body to chronic stress. In this review, tests used in the assessment of HPA axis function and the HPA axis alterations found in CFS and FMS are discussed in detail.

Cortisol and severe fatigue: a longitudinal study in adolescent girls

Fatigue is a common complaint among adolescents, especially in girls, and is associated with high rates of school absenteeism. Severe fatigue is often accompanied by psychological and physical symptoms. In the chronic fatigue syndrome (CFS) functioning of the hypothalamic-pituitary-adrenal (HPA)-axis has previously been found to be altered. The aim of the present study was to investigate whether cortisol production is deviant in fatigued adolescent girls from the general population and to study longitudinal changes in fatigue in association with possible changes in HPA-axis functioning. In the cross-sectional part of the study the cortisol response to awakening (CAR) and to a low-dose oral dexamethasone were examined in a group of fatigued adolescent girls (n=87) in comparison to a non-fatigued control group (n=77). Questionnaires regarding fatigue, depression, anxiety, sleep quality, somatic symptoms and CFS-related symptoms were filled out. Follow up measurements were performed after 6 and 12 months. While the fatigued and non-fatigued group differed remarkably on all symptom self-reports, no differences between groups in CAR and response to dexamethasone were observed. Girls in the fatigued group remained fatigued over time and reported high levels of other psychological and physical symptoms during the whole year of the study. The CAR varied between time points but correlated non-systematically with situational characteristics or symptom reports. We conclude that trait-like fatigue, as measured in a sample of adolescent girls from a high school population, is not reflected in a dysregulation as assessed on the level of salivary cortisol after awakening.

Recent trends in behavioral medicine

PURPOSE OF REVIEW

Behavioral medicine is an interdisciplinary field, integrating research from a variety of disciplines. This review focuses on recent advances and developments in behavioral medicine.

RECENT FINDINGS

Stress, as well as having a role in the etiology and maintenance of somatic disease and somatoform disorders, is an important factor in the behavioral medicine literature. Consequentially, recent advances in psychological interventions targeting these conditions were developed. Furthermore, a variety of psychobiological mechanistic studies investigating the dysregulations of stress axes in conditions relevant to behavioral medicine have been undertaken.

SUMMARY

Studies investigating factors and processes relevant to health and illness clearly demonstrate the impact of psychosocial factors such as stress. The biopsychosocial perspective becomes increasingly sophisticated, focusing on specific disease processes and empirically tested and effective interventions.

Chronic fatigue syndrome: an update focusing on phenomenology and pathophysiology

PURPOSE OF REVIEW

Chronic fatigue syndrome is a controversial condition especially concerning its clinical definition and aetiopathogenesis. Most recent research progress has been made in phenomenology and pathophysiology and we focused our review on these two areas.

RECENT FINDINGS

The phenomenology research supports the notion of a discrete fatigue syndrome which can be distinguished from depression and anxiety. The current case definition, however, may need an improvement based on empirical data. Recent advances in understanding the pathophysiology of chronic fatigue syndrome continue to demonstrate the involvement of the central nervous system. Hyperserotonergic state and hypoactivity of the hypothalamic-pituitary-adrenal axis constitute other findings, but the question of whether these alterations are a cause or consequence of chronic fatigue syndrome still remains unanswered. Immune system involvement in the pathogenesis seems certain but the findings on the specific mechanisms are still inconsistent. Genetic studies provide some evidence of the syndrome being a partly genetic condition, but environmental effects seem to be still predominant and identification of specific genes is still at a very early stage.

SUMMARY

The recent findings suggest that further research is needed in improving the current case definition; investigating overlaps and boundaries among various functional somatic syndromes; answering the question of whether the pathophysiologic findings are a cause or consequence; and elucidating the involvement of the central nervous system, immune system and genetic factors.