Adrenal fatigue does not exist: a systematic review

Understanding the relationships between physiological and psychosocial stress, cortisol and cognition

Stress is viewed as a state of real or perceived threat to homeostasis, the management of which involves the endocrine, nervous, and immune systems. These systems work independently and interactively as part of the stress response. The scientific stress literature, which spans both animal and human studies, contains heterogeneous findings about the effects of stress on the brain and the body. This review seeks to summarise and integrate literature on the relationships between these systems, examining particularly the roles of physiological and psychosocial stress, the stress hormone cortisol, as controlled by the hypothalamic-pituitary-adrenal (HPA) axis, and the effects of stress on cognitive functioning. Health conditions related to impaired HPA axis functioning and their associated neuropsychiatric symptoms will also be considered. Lastly, this review will provide suggestions of clinical applicability for endocrinologists who are uniquely placed to measure outcomes related to endocrine, nervous and immune system functioning and identify areas of intervention.

A taxonomy of risk-associated alternative health practices: A Delphi study

Defining alternative health care and the recording of associated adverse events and harm remains problematic. This Canadian study aimed to establish and classify risk-associated alternative health practices in a Delphi study undertaken with an interdisciplinary panel of 17 health experts in 2020. It provides a new functional definition of alternative health care and an initial taxonomy of risk-associated alternative health care practices. A number of risk-associated practices were identified and categorized into general practices that conflict with biomedical care or largely untested therapies, alternative beliefs systems, physical manipulative alternative therapies, and herbal and nutritional supplements. Some risk significant harms including major physical injuries or even death. The lack of systematic methods for recording adverse events in alternative health care makes establishing the frequency of such events challenging. However, it is important that people engaging with alternative health care understand they are not necessarily risk-free endeavours, and what those risks are.

The biology of burnout: Causes and consequences

OBJECTIVES

Burnout is a state of exhaustion resulting from prolonged and excessive workplace stress. We sought to examine biological underpinnings of burnout, focussing on mechanisms and physical consequences.

METHODS

We searched the literature on burnout and evaluated studies examining biological parameters in patient populations (i.e. 'clinical' burnout) as well as in individuals from the general population judged as having some degree of burnout evaluated using a dimensional approach.

RESULTS

Findings suggest that burnout is associated with sustained activation of the autonomic nervous system and dysfunction of the sympathetic adrenal medullary axis, with alterations in cortisol levels. Limited studies have also shown altered immune function and changes in other endocrine systems. Consequences of burnout include increased allostatic load, structural and functional brain changes, excito-toxicity, systemic inflammation, immunosuppression, metabolic syndrome, cardiovascular disease and premature death. Limitations of studies include variability in study populations, low specificity of burnout measures, and mostly cross-sectional studies precluding examination of changes across the course of burnout.

CONCLUSIONS

Further examination of biological mechanisms of burnout would benefit from more homogeneous clinical samples, challenge tests and prospective studies. This would assist in differentiation from conditions such as depression and aid with development of specific treatment targets for burnout.

Androgen Misuse and Abuse

Androgens are potent drugs requiring prescription for valid medical indications but are misused for invalid, unproven, or off-label reasons as well as being abused without prescription for illicit nonmedical application for performance or image enhancement. Following discovery and first clinical application of testosterone in the 1930s, commercialization of testosterone and synthetic androgens proliferated in the decades after World War II. It remains among the oldest marketed drugs in therapeutic use, yet after 8 decades of clinical use, the sole unequivocal indication for testosterone remains in replacement therapy for pathological hypogonadism, organic disorders of the male reproductive system. Nevertheless, wider claims assert unproven, unsafe, or implausible benefits for testosterone, mostly representing wishful thinking about rejuvenation. Over recent decades, this created an epidemic of testosterone misuse involving prescription as a revitalizing tonic for anti-aging, sexual dysfunction and/or obesity, where efficacy and safety remains unproven and doubtful. Androgen abuse originated during the Cold War as an epidemic of androgen doping among elite athletes for performance enhancement before the 1980s when it crossed over into the general community to become an endemic variant of drug abuse in sufficiently affluent communities that support an illicit drug industry geared to bodybuilding and aiming to create a hypermasculine body physique and image. This review focuses on the misuse of testosterone, defined as prescribing without valid clinical indications, and abuse of testosterone or synthetic androgens (androgen abuse), defined as the illicit use of androgens without prescription or valid indications, typically by athletes, bodybuilders and others for image-oriented, cosmetic, or occupational reasons.

Das gestresste Immunsystem und Autoimmunität

Über einen möglichen Zusammenhang zwischen psychologischem Stress, Immunsystem und Autoimmunität wird schon lange debattiert. Erkenntnisse aus der Grundlagen- und epidemiologischen Forschung, die das Verständnis für diesen komplexen Zusammenhang erhöhen werden in dieser kurzen Übersicht zusammengestellt. Zunächst werden bekannte anatomisch-physiologische Grundlagen für einen Zusammenhang zwischen psychologischem Stress und Immunsystem dargestellt. Es wird beschrieben, dass die Interaktion zwischen Gehirn über autonomes Nervensystem und Hormonsystem bis zur Immunzelle mit entsprechenden Rezeptoren für Neurotransmitter und Hormone mittlerweile bis auf die molekulare Ebene gut beschrieben ist. Im Rahmen der akuten Stressreaktion treten charakteristische Veränderungen im Immunsystem auf, die ebenfalls gut dokumentiert sind. In einem zweiten Teil wird dann beschrieben welche Veränderungen im Rahmen einer chronischen Stressbelastung am Immunsystem auftreten können und zuletzt wird diskutiert inwiefern diese Veränderungen auch für pathophysiologische Zustände des Immunsystems, z. B. im Rahmen von Autoimmunerkrankungen, relevant sein könnten. Zusammenfassend führt akuter Stress, im Sinne der optimalen Vorbereitung einer fight&flight Situation, zu einer Steigerung der Immunfunktion v. a. der humoralen Immunität, wohingegen die Auswirkungen von chronischem Stress weniger klar definiert sind und es eher zu einer Immundysregulation mit verminderter basaler Immunfunktion, v. a. der zytotoxischen Funktion aber einer gesteigerten Reaktion nach Aktivierung, v. a. im angeborenen Immunschenkel kommt. Epidemiologische Daten belegen gut, dass chronischer Stress zu einer erhöhten Suzeptibilität für Autoimmunerkrankungen führt. Erste klinische Anwendungen, wie beispielsweise die gezielte neuronale Stimulation des N. vagus sind in Erprobung, für einen breiteren klinischen Einsatz sollten aber die biologischen Netzwerkstrukturen noch besser verstanden werden, um die besten Angriffspunkte zu finden.

Mechanisms of Food-Induced Symptom Induction and Dietary Management in Functional Dyspepsia

Functional dyspepsia (FD) is a common disorder of gut-brain interaction, characterised by upper gastrointestinal symptom profiles that differentiate FD from the irritable bowel syndrome (IBS), although the two conditions often co-exist. Despite food and eating being implicated in FD symptom induction, evidence-based guidance for dietetic management of FD is limited. The aim of this narrative review is to collate the possible mechanisms for eating-induced and food-related symptoms of FD for stratification of dietetic management. Specific carbohydrates, proteins and fats, or foods high in these macronutrients have all been reported as influencing FD symptom induction, with removal of 'trigger' foods or nutrients shown to alleviate symptoms. Food additives and natural food chemicals have also been implicated, but there is a lack of convincing evidence. Emerging evidence suggests the gastrointestinal microbiota is the primary interface between food and symptom induction in FD, and is therefore a research direction that warrants substantial attention. Objective markers of FD, along with more sensitive and specific dietary assessment tools will contribute to progressing towards evidence-based dietetic management of FD.

The hypothalamo-pituitary-adrenal axis and the autonomic nervous system in burnout

Burnout constitutes a serious health concern in the modern working environment. It is a stress-related condition that has developed as a result of a prolonged psychosocial stress exposure causing a persistent mismatch between demands and resources. The main symptom is emotional exhaustion, but physical fatigue, diminished professional efficacy, cynicism, and cognitive impairments are also associated with this condition. Burnout has been used both as a psychologic term in occupational settings and as a clinical diagnosis in patient populations, and there is currently no universally accepted definition and diagnostic criteria of burnout. It has been hypothesized that the two main stress response systems, the autonomic nervous system (ANS) and the hypothalamus-pituitary-adrenal axis (HPA axis), are involved in the pathogenesis of burnout. A common hypothesis is that in the early stages of chronic stress, the HPA axis and sympathetic ANS activity tend to be higher, while it will decrease with a longer duration of chronic stress to ultimately reach a state of hypoactivity in clinical burnout. The current research in this field shows many contradictory results. Thus there is no compelling evidence of either ANS or HPA dysfunction in burnout. However, there is partial support for the hypothesis of HPA and sympathetic hyperactivity in early stages, and HPA hyporeactivity and low vagal activity in more severe burnout cases, but high-quality studies investigating the causal links are still lacking.

Stress, inflammation, depression, and dementia associated with phosphate toxicity

Depression and dementia are predicted to increase within aging global populations. Pathophysiological effects of phosphate toxicity, dysregulated amounts of accumulated phosphorus in body tissue, are under-investigated in association with stress, inflammation, depression, and dementia. A comparative analysis of concepts in cited sources from the research literature was used to synthesize novel themes exploring the disease-oriented neuroscience effects of phosphate toxicity. Phosphate toxicity is associated with activation of cellular stress response systems and inflammation. Cortisol released by the hypothalamic-pituitary-adrenal axis responds to stress and inflammation associated with phosphate toxicity and depression. In a reciprocal interaction, phosphate toxicity is capable of harming adrenal gland function, possibly leading to adrenal insufficiency and depression. Furthermore, Alzheimer's disease is associated with hyperphosphorylated tau which self-assembles into neurofibrillary tangles from excessive amounts of phosphate in the brain and central nervous system. Future research should investigate dietary phosphate modification to reduce potential pathophysiological effects of phosphate toxicity in stress, inflammation, depression, and cognitive decline which affects global populations.

OFF-LABEL USE AND MISUSE OF TESTOSTERONE, GROWTH HORMONE, THYROID HORMONE, AND ADRENAL SUPPLEMENTS: RISKS AND COSTS OF A GROWING PROBLEM

Over the past few decades, there has been an unprecedented rise in off-label use and misuse of testosterone, growth hormone, thyroid hormone, and adrenal supplements. Testosterone therapy is often promoted to men for the treatment of low energy, lower libido, erectile dysfunction, and other symptoms. Growth hormone is used in attempts to improve athletic performance in athletes and to attenuate aging in older adults. Thyroid hormone and/or thyroid supplements or boosters are taken to treat fatigue, obesity, depression, cognitive impairment, impaired physical performance, and infertility. Adrenal supplements are used to treat common nonspecific symptoms due to "adrenal fatigue," an entity that has not been recognized as a legitimate medical diagnosis. Several factors have contributed to the surge in off-label use and misuse of these hormones and supplements: direct-to-consumer advertising, websites claiming to provide legitimate medical information, and for-profit facilities promoting therapies for men's health and anti-aging. The off-label use and misuse of hormones and supplements in individuals without an established endocrine diagnosis carries known and unknown risks. For example, the risks of growth hormone abuse in athletes and older adults are unknown due to a paucity of studies and because those who abuse this hormone often take supraphysiologic doses in sporadic intervals. In addition to the health risks, off-label use of these hormones and supplements generates billions of dollars of unnecessary costs to patients and to the overall health-care system. It is important that patients honestly disclose to their providers off-label hormone use, as it may affect their health and treatment plan. General medical practitioners and adult endocrinologists should be able to begin a discussion with their patients regarding the unfavorable balance between the risks and benefits associated with off-label use of testosterone, growth hormone, thyroid hormone, and adrenal supplements. Abbreviations: DHEA = dehydroepiandrosterone; FDA = U.S. Food and Drug Administration; GH = growth hormone; IGF-1 = insulin-like growth factor 1; LT3 = L-triiodothyronine; LT4 = levothyroxine; T3 = total triiodothyronine; T4 = thyroxine; TSH = thyroid-stimulating hormone.

Enhancement of hypothalamic-pituitary activity in male athletes: evidence of a novel hormonal mechanism of physical conditioning

BACKGROUND

Exercise is known to induce multiple beneficial conditioning processes. Conversely, although exercise may generate several hormonal effects, an intrinsic hormonal conditioning process has not been reported. In the Endocrine and Metabolic Responses on Overtraining Syndrome (EROS) study, we observed inherent and independent conditioning processes of the hypothalamic-pituitary axes in athletes. Our objective is to describe the theory of the novel hormonal conditioning mechanism using the findings from the EROS study.

METHODS

In this cross-sectional study, we selected 25 healthy athletes (ATL) and 12 non-physically active healthy controls (NPAC), 18-50 years old, males, with BMI 20-30 kg/m², with similar baseline characteristics, who underwent gold-standard exercise-independent tests: cosyntropin stimulation test (CST) and insulin tolerance test (ITT), to evaluate cortisol response to CST, and ACTH, cortisol, GH, and prolactin responses to an ITT.

RESULTS

Responses to ITT were significantly earlier and higher in ATL than NPAC for cortisol [Mean ± SD: 21.7 ± 3.1 vs 16.9 ± 4.1 μg/dL; p < 0.001], GH [Median (95% CI): 12.73 (1.1-38.1) vs 4.80 (0.33-27.36) μg/L; p = 0.015], and prolactin [24.3 (10.5-67.45) vs 10.50 (6.21-43.44) ng/mL; p = 0.002]. Cortisol response to CST was similar between ATL and NPAC. During ITT, cortisol, GH, and ACTH mean increase in ATL were 52.2, 265.2, and 18.6% higher than NPAC, respectively. Prolactin response was absent in NPAC, while present in ATL.

CONCLUSIONS

We found sufficient evidence to propose the existence of a diffuse enhancement of the hypothalamic-pituitary activity in athletes, not restricted to any axis, showing an intrinsic and independent process of "hormonal conditioning" in athletes, similar to those observed in the cardiovascular and neuromuscular systems. This novel conditioning process may be the missing link for understanding the improved responses observed in athletes to harmful situations, traumas, infections, inflammations, and psychiatric conditions.

Burnout and Metabolic Syndrome in Female Nurses: An Observational Study

Nurses are at risk of having burnout due to workload and job stress-studies have reported that chronic stress is associated with metabolic syndrome. This study aimed to assess the association between burnout and metabolic syndrome in a sample of female nurses. Data were collected from a cross-sectional study from 2016 to 2018 in a tertiary hospital in Mexico City. All nurses that work in the hospital were invited to participate. Information pertaining to sociodemographic (age, education level), work (labor seniority, service area, shift work), anthropometric (weight, waist circumference, blood pressure) and biochemical (glucose, serum lipids) variables were collected. Burnout was assessed using the Maslach Burnout Inventory test, and metabolic syndrome was defined according to the International Diabetes Federation criteria. A total of 168 nurses participated with a median age of 44 years. The prevalence of burnout and metabolic syndrome was 19.6% and 38.7%, respectively. There was no association between burnout and metabolic syndrome (p = 0.373). However, associations of emotional exhaustion (aOR: 14.95; 95% CI: 1.5-148.7), personal accomplishment (aOR: 0.13; 95% CI: 0.01-0.99), and night shift (aOR: 12.39; 95% CI: 1.02-150.5) with increased waist circumference were found. Strategies are needed to prevent burnout and metabolic syndrome in nurses, especially in those who work at night shift.

Hair Cortisol in Sheltered Cows and Its Association with Other Welfare Indicators

India, the country with the largest population of dairy cows in the world, has a policy of retiring abandoned and non-lactating cows in shelters, but the level of provision for their welfare in these shelters is unclear. Cows in 54 shelters across India were assessed for historic evidence of physiological stress, through determination of hair cortisol in 540 samples from 10 cows in each shelter by enzyme immunoassay. Animal-based and shelter resource-based welfare measures were recorded and correlations with the hair cortisol investigated by multivariable analysis. High hair cortisol concentrations were associated with dung in the lying area of the cowshed, a low dry bulb temperature there and little cow access to yards, as shelter-based variables. At a cow level, high hair cortisol concentrations were associated with dirty flanks, hock joint ulceration, carpal joint injuries, body lesions, dehydration, an empty rumen, old age, and low levels of body hair loss. Hair cortisol level promises to be an effective biomarker of stress in cows when conducting studies under field conditions.

MECHANISMS IN ENDOCRINOLOGY: Endocrine and immunological aspects of burnout: a narrative review

Burnout has several different definitions, and attempts have been made to discriminate between burnout as a psychological construct and burnout as a clinical entity. A large body of research has focused on elucidating the biological link between stress exposure and burnout and/or finding a clinically usable biomarker for burnout. The objective of this narrative review is to summarize the main endocrine and immune findings in relation to burnout. The literature has primarily focused on dysregulation of the hypothalamus-pituitary-adrenal (HPA) axis. However, albeit the large body of studies, it cannot be concluded that clear effects are seen on HPA axis function in people with burnout. The HPA axis and anabolic acute reactivity to stress might be affected in clinical burnout. Plausible, effects of chronic stress might rather be seen when measuring responses to acute stress rather than resting state hormonal levels. Studies on other hormones, including thyroid hormones, prolactin and growth hormone in burnout subjects are inconclusive. It is important to note that this field is faced with many methodological challenges, one being the diurnal and pulsatile nature of many of the hormones of interest, including cortisol, which is not always considered. Another challenge is the heterogeneity regarding definitions and measurements of stress and burnout. Existing studies on burnout and immune function are heterogeneous regarding the results and no firm conclusion can be made if clinically relevant immune changes are present in burnout subjects. An overall conclusion is that existing research cannot confirm any homogenous reliable endocrinological or immunological changes related to burnout.

Inter-correlations Among Clinical, Metabolic, and Biochemical Parameters and Their Predictive Value in Healthy and Overtrained Male Athletes: The EROS-CORRELATIONS Study

Objectives: The Endocrine and Metabolic Responses on Overtraining Syndrome (EROS) study identified multiple hormonal and metabolic conditioning processes in athletes, and underlying mechanisms and biomarkers of overtraining syndrome (OTS). The present study's objective was to reveal independent predictors and linear correlations among the parameters evaluated in the EROS study to predict clinical, metabolic, and biochemical behaviors in healthy and OTS-affected male athletes. Methods: We used multivariate linear regression and linear correlation to analyze possible combinations of the 38 parameters evaluated in the EROS study that revealed significant differences between healthy and OTS-affected athletes. Results: The testosterone-to-estradiol (T:E) ratio predicted the measured-to-predicted basal metabolic rate (BMR) ratio; the T:E ratio and total testosterone level were inversely predicted by fat mass and estradiol was not predicted by any of the non-modifiable parameters. Early and late growth hormone, cortisol, and prolactin responses to an insulin tolerance test (ITT) were strongly correlated. Hormonal responses to the ITT were positively correlated with fat oxidation, predicted-to-measured BMR ratio, muscle mass, and vigor, and inversely correlated with fat mass and fatigue. Salivary cortisol 30 min after awakening and the T:E ratio were inversely correlated with fatigue. Tension was inversely correlated with libido and directly correlated with body fat. The predicted-to-measured BMR ratio was correlated with muscle mass and body water, while fat oxidation was directly correlated with muscle mass and inversely correlated with fat mass. Muscle mass was directly correlated with body water, and extracellular water was directly correlated with body fat and inversely correlated with body water and muscle mass. Conclusions: Hypothalamic-pituitary responses to stimulation were diffuse and indistinguishable between the different axes. A late hormonal response to stimulation, increased cortisol after awakening, and the T:E ratio were correlated with vigor and fatigue. The T:E ratio was also correlated with body metabolism and composition, testosterone was predicted by fat mass, and estradiol predicted anger. Hydration status was inversely correlated with edema, and inter-correlations were found among fat oxidation, hydration, and body fat.

Hypothalamic-Pituitary-Adrenal (HPA) Axis Functioning in Overtraining Syndrome: Findings from Endocrine and Metabolic Responses on Overtraining Syndrome (EROS)-EROS-HPA Axis

BACKGROUND

Overtraining syndrome (OTS) results from excessive training load without adequate recovery and leads to decreased performance and fatigue. The pathophysiology of OTS in athletes is not fully understood, which makes accurate diagnosis difficult. Previous studies indicate that alterations in the hypothalamus-pituitary-adrenal (HPA) axis may be responsible for OTS; however, the data is not conclusive. This study aimed to compare, through gold standard and exercise-independent tests, the response of the HPA axis in OTS-affected athletes (OTS group) to healthy physically active subjects (ATL group) and healthy non-active subjects (NCS group).

METHODS

Selected subjects were evaluated for cortisol response to a 250-μg cosyntropin stimulation test (CST), cortisol and adrenocorticotropic hormone (ACTH) responses during an insulin tolerance test (ITT), and salivary cortisol rhythm (SCR).

RESULTS

A total of 51 subjects were included (OTS, n = 14; ATL, n = 25; and NCS, n = 12). Cortisol response in the CST was similar among the three groups. Conversely, mean cortisol response during an ITT was significantly higher in ATL (21.7 μg/dL; increase = 9.2 μg/dL) compared to OTS (17.9 μg/dL; 6.3 μg/dL) and NCS (16.9 μg/dL; 6.0 μg/dL) (p ≤ 0.001; p = 0.01). Likewise, median ACTH response during an ITT was significantly higher in ATL (91.4 pg/mL; increase = 45.1 pg/mL) compared to OTS (30.3 pg/mL; 9.7 pg/mL) and NCS (51.4 pg/mL; 38.0 pg/mL) (p = 0.006; p = 0.004). For SCR, mean cortisol 30 min after awakening was significantly higher in ATL (500 ng/dL) compared to OTS (323 ng/dL) and NCS (393 ng/dL) (p = 0.004). We identified the following cutoffs that could help exclude or confirm OTS: cortisol level at 30 min after awakening (exclusion = > 530 ng/dL); cortisol response to ITT (exclusion = > 20.5 μg/dL; confirmation = < 17 μg/dL or increase < 9.5 μg/dL); and ACTH response (exclusion = > 106 pg/mL or increase > 70 pg/mL; confirmation = < 35 pg/mL and increase < 14.5 pg/mL).

CONCLUSION

The findings of the present study showed that healthy athletes disclose adaptions to exercises that helped improve sport-specific performance, whereas this sort of hormonal conditioning was at least partially lost in OTS, which may explain the decrease in performance in OTS.