Cortisol, Health, and Coping in Patients with Nonspecific Low Back Pain

Examining Reactivity and Recovery Patterns of Pain-Evoked Cortisol and Alpha-Amylase Trajectories: Relations Between Psychological Markers of Risk and Resilience

Chronic low back pain (cLBP) is one of the leading causes of disability globally and represents an enormous burden to aging adults. While numerous factors contribute to cLBP, dysregulation in the hypothalamic-pituitary-adrenal axis and autonomic nervous system functioning have been implicated in its pathogenesis. It is well documented that negative psychological states can modulate biological stress responsivity in chronic pain; however, little is known regarding the influence of positive psychological factors in this relationship. The aim of this study was to examine the association between psychological risk and resilience factors with patterns of physiological stress reactivity and recovery in 60 older adults with cLBP. Participants completed measures of hope, optimism, pain catastrophizing, and perceived stress, and underwent psychophysical pain testing assessing responses to painful pressure, heat, and cold stimuli. Salivary samples were obtained prior to pain induction and at 7 time points spanning 90 minutes after pain testing terminated. To examine reactivity and recovery profiles in hypothalamic-pituitary-adrenal axis and autonomic nervous system function, samples were assayed for cortisol and alpha-amylase, respectively. Results revealed higher levels of hope and optimism were associated with increased cortisol reactivity (p's < .003) and more rapid recovery (p's = .001). Further, pain catastrophizing and perceived stress were associated with cortisol reactivity, with lower levels of these factors predicting larger increases in cortisol from baseline to peak levels (p's < .04). No significant differences in reactivity or recovery patterns emerged for alpha-amylase. Overall, findings highlight the role of psychological risk and resilience factors in modulating physiological stress reactivity. PERSPECTIVE: This article investigated whether psychosocial risk and resilience factors were associated with stress reactivity and recovery in response to laboratory-based pain testing in older adults with chronic low back pain. Results indicate that high resilience factors may be protective by modulating adrenocortical reactivity and recovery profiles.

Factors Affecting the Use of Pain-Coping Strategies in Individuals with Cerebral Palsy and Individuals with Typical Development

Many individuals with cerebral palsy (CP) suffer from pain and must develop pain-coping strategies, although the factors determining them are unknown. This observational study aims at exploring the association between different pain-coping strategies and factors such as age, sex, pain, health status, sleep or motor and cognitive function in individuals with cerebral palsy (CP) and typically developing peers (TD). Main caregivers of 94 individuals with CP (age range = 6-69 years, mean age = 17.78 (10.05)) and the closest relative of 145 individuals with TD (age range = 6-51 years, mean age = 19.13 (12.87)) completed questionnaires on the previous topics (Parent Report of the PEDsQL Pediatric Coping Inventory, the Health Utility Index HUI-3, Epworth Sleepiness Score and the Pittsburgh Sleep Quality Index). Pain presence, duration, intensity, location and ratings of current and worst pain in the last week in an 11-point numerical rating scale were assessed in an interview. Global health was the best predictor the of use of any type of pain-coping strategy, including cognitive self-instruction, problem-solving, distraction, seeking social support and catastrophizing, in both individuals with CP and individuals with TD. However, different health attributes predicted their use in each population. Emotional health was the best predictor in individuals with CP, whereas cognition and pain were the best predictors in individuals with TD. Speech ability was a predictor in both groups. In conclusion, the assessment of health attributes such as emotional health and speech may help design specific interventions for enhancing self-efficacy and adaptive pain coping skills.

Chronic Pain and Psychiatric Conditions

Introduction

Chronic pain is a common condition with high socioeconomic and public health burden. A wide range of psychiatric conditions are often comorbid with chronic pain and chronic pain conditions, negatively impacting successful treatment of either condition. The psychiatric condition receiving most attention in the past with regard to chronic pain comorbidity has been major depressive disorder, despite the fact that many other psychiatric conditions also demonstrate epidemiological and genetic overlap with chronic pain. Further understanding potential mechanisms involved in psychiatric and chronic pain comorbidity could lead to new treatment strategies both for each type of disorder in isolation and in scenarios of comorbidity.

Methods

This article provides an overview of relationships between DSM-5 psychiatric diagnoses and chronic pain, with particular focus on PTSD, ADHD, and BPD, disorders which are less commonly studied in conjunction with chronic pain. We also discuss potential mechanisms that may drive comorbidity, and present new findings on the genetic overlap of chronic pain and ADHD, and chronic pain and BPD using linkage disequilibrium score regression analyses.

Results

Almost all psychiatric conditions listed in the DSM-5 are associated with increased rates of chronic pain. ADHD and BPD are significantly genetically correlated with chronic pain. Psychiatric conditions aside from major depression are often under-researched with respect to their relationship with chronic pain.

Conclusion

Further understanding relationships between psychiatric conditions other than major depression (such as ADHD, BPD, and PTSD as exemplified here) and chronic pain can positively impact understanding of these disorders, and treatment of both psychiatric conditions and chronic pain.

Immune-inflammatory and hypothalamic-pituitary-adrenal axis biomarkers are altered in patients with non-specific low back pain: A systematic review

This systematic review aimed to investigate immune-inflammatory and hypothalamic-pituitary-adrenal (HPA) axis biomarkers in individuals with non-specific low back pain (NSLBP) compared to healthy control. The search was performed in five databases until 4 November 2021. Two reviewers independently conducted screenings, data extraction, risk of bias, and methodological quality assessment of 14 unique studies. All studies reported the source of the fluid analyzed: nine studies used serum, two used plasma, one used serum and plasma, and two studies used salivary cortisol. We found preliminary and limited evidence (only one study for each biomarker) of increased levels in growth differentiation factor 15 (GDF-15), interleukin-23 (IL-23), transforming growth factor–beta (TGF-β), and soluble tumor necrosis factor receptor 1 (sTNF-R1) in NSLBP. Inconsistent and limited evidence was identified for interleukin-10 (IL-10). Although C-reactive protein (CRP), interleukin-6 (IL-6), and tumor necrosis factor–alpha (TNF-α) levels appear to increase in NSLBP, only one study per each biomarker reported statistically significant differences. Interleukin-1 beta (IL-1β), interleukin-17 (IL-17), interferon gamma (IFN-γ), and high-sensitivity CRP (hsCRP) showed no significant differences. Regarding cortisol, one study showed a significant increase and another a significant decrease. More robust evidence between GDF-15, IL-23, TGF-β, and sTNF-R1 with NSLBP is needed. Moreover, contrary to the findings reported in previous studies, when comparing results exclusively with healthy control, insufficient robust evidence for IL-6, TNF-α, and CRP was found in NSLBP. In addition, cortisol response (HPA-related biomarker) showed a dysregulated functioning in NSLBP, with incongruent evidence regarding its directionality. Therefore, our effort is to find adjusted evidence to conclude which immune-inflammatory and HPA axis biomarkers are altered in NSLBP and how much their levels are affected.

Fatigue severity and avoidance among individuals with chronic disease: A meta-analysis

OBJECTIVE

Fatigue is a common, debilitating symptom experienced by individuals with chronic disease. Avoidance, or the act of evading unwanted experiences, is associated with fatigue across chronic disease samples. The current study sought to determine the strength of association between fatigue severity and avoidance in individuals with chronic disease.

METHODS

PubMed, PsycINFO, CINAHL, and ProQuest Dissertations and Theses databases were searched. Eligible studies measured fatigue and avoidance in chronic disease samples. Sixty-six studies were included. Data analyses were conducted in Rstudio. A random effects model was employed, and a weighted mean effect size was computed for fatigue severity and avoidance. Mixed-effects meta-regression analyses were conducted to examine moderating variables, including patient, clinical, and measurement characteristics. Publication bias was examined using funnel plot, trim-and-fill, and p-curve.

RESULTS

The meta-analysis comprised of 71 unique patient samples from 66 studies. The total number of included participants was 13,024. A small, positive association was found between fatigue severity and avoidance, r(71) = 0.22, p < .001, 95% CI [0.18-0.27], SE = 0.02. There was also significant heterogeneity, Q(70) = 349.96, p < .001. Moderator analyses examining age, sex, illness duration, avoidance type, and disease sample were all non-significant. Regarding publication bias, trim-and-fill resulted in a modified weighted mean effect size (r(83) = 0.18, p < .001) and a p-curve analysis supported the evidential value of the current analysis.

CONCLUSION

Findings support that among individuals with chronic disease, fatigue severity and avoidance are positively associated, which has implications for behavioral interventions in this population.

Sciatic nerve injury rebalances the hypothalamic-pituitary-adrenal axis in rats with persistent changes to their social behaviours

Increased glucocorticoids characterise acute pain responses, but not the chronic pain state, suggesting specific modifications to the hypothalamic-pituitary-adrenal (HPA)-axis preventing the persistent nature of chronic pain from elevating basal glucocorticoid levels. Individuals with chronic pain mount normal HPA-axis responses to acute stressors, indicating a rebalancing of the circuits underpinning these responses. Preclinical models of chronic neuropathic pain generally recapitulate these clinical observations, but few studies have considered that the underlying neuroendocrine circuitry may be altered. Additionally, individual differences in the behavioural outcomes of these pain models, which are strikingly similar to the range of behavioural subpopulations that manifest in response to stress, threat and motivational cues, may also be reflected in divergent patterns of HPA-axis activity, which characterises these other behavioural subpopulations. We investigated the effects of sciatic nerve chronic constriction injury (CCI) on adrenocortical and hypothalamic markers of HPA-axis activity in the subpopulation of rats showing persistent changes in social interactions after CCI (Persistent Effect) and compared them with rats that do not show these changes (No Effect). Basal plasma corticosterone did not change after CCI and did not differ between groups. However, adrenocortical sensitivity to adrenocorticotropic hormone (ACTH) diverged between these groups. No Effect rats showed large increases in basal plasma ACTH with no change in adrenocortical melanocortin 2 receptor (MC₂ R) expression, whereas Persistent Effect rats showed modest decreases in plasma ACTH and large increases in MC₂ R expression. In the paraventricular nucleus of the hypothalamus of Persistent Effect rats, single labelling revealed significantly increased numbers of corticotropin releasing factor (CRF) +ve and glucocorticoid receptor (GR) +ve neurons. Double-labelling revealed fewer GR +ve CRF +ve neurons, suggesting a decreased hypothalamic sensitivity of CRF neurons to circulating corticosterone in Persistent Effect rats. We suggest that in addition to rebalancing the HPA-axis, the increased CRF expression in Persistent Effect rats contributes to changes in complex behaviours, and in particular social interactions.

Persistent inflammatory pain is linked with anxiety-like behaviors, increased blood corticosterone, and reduced global DNA methylation in the rat amygdala

Chronic pain increases the risk of developing anxiety, with limbic areas being likely neurological substrates. Despite high clinical relevance, little is known about the precise behavioral, hormonal, and brain neuroplastic correlates of anxiety in the context of persistent pain. Previous studies have shown that decreased nociceptive thresholds in chronic pain models are paralleled by anxiety-like behavior in rats, but there are conflicting ideas regarding its effects on the stress response and circulating corticosterone levels. Even less is known about the molecular mechanisms through which the brain encodes pain-related anxiety. This study examines how persistent inflammatory pain in a rat model would impact anxiety-like behaviors and corticosterone release, and whether these changes would be reflected in levels of global DNA methylation in brain areas involved in stress regulation. Complete Freund's adjuvant (CFA) or saline was administered in the right hindpaw of adult male Wistar rats. Behavioral testing included the measurement of nociceptive thresholds (digital anesthesiometer), motor function (open field test), and anxiety-like behaviors (elevated plus maze and the dark-light box test). Corticosterone was measured via radioimmunoassay. Global DNA methylation (enzyme immunoassay) as well as DNMT3a levels (western blotting) were quantified in the amygdala, prefrontal cortex, and ventral hippocampus. CFA administration resulted in persistent reduction in nociceptive threshold in the absence of locomotor abnormalities. Increased anxiety-like behaviors were observed in the elevated plus maze and were accompanied by increased blood corticosterone levels 10 days after pain induction. Global DNA methylation was decreased in the amygdala, with no changes in DNMT3a abundance in any of the regions examined. Persistent inflammatory pain promotes anxiety -like behaviors, HPA axis activation, and epigenetic regulation through DNA methylation in the amygdala. These findings describe a molecular mechanism that links pain and stress in a well-characterized rodent model.

Effects of photobiomodulation and deep water running in patients with chronic non-specific low back pain: a randomized controlled trial

Photobiomodulation therapy (PBM) is often used to treat musculoskeletal disorders such as chronic non-specific low back pain (NSCLBP) as it can have positive effects on biomarkers-creatine kinase (CK) and serum cortisol levels-related to stress caused by physical exercise, such as deep water running (DWR) or by pain. The aim of this study was to evaluate the effects of the combination of PBM and aquatic exercise (DWR) on the intensity of pain, disability, 6-min walk test adapted (6WTA), and on cortisol and creatine kinase (CK) levels in a population with NSCLBP. The participants were allocated into three groups: TG_PBM (Photobiomodulation and Training Group), TG_PLA (Placebo Photobiomodulation and Training Group), and the G_PBM (Photobiomodulation Group). Information regarding anthropometric data, blood pressure, and heart rate were collected, and the questionnaires were applied: IPAQ-Short Form, Oswestry Disability Index, and the Visual Analog Scale for Pain. The submaximal exercise test (6WTA) was performed. Blood was collected for analysis of cortisol and CK levels. The training sessions were performed twice a week, for 4 weeks. In the intragroup comparisons, there were statistically significant changes in the TG_PBM and G_PBM groups in the outcomes pain intensity, disability (reductions in both groups), and in cortisol (increased in the TG_PBM and reduced in the G_PBM); in the TG_PLA group, there was a statistically significant reduction only in the outcome of pain intensity. In the intergroup comparison, in the comparison between TG_PBM and TG_PLA, there was a statistically significant difference in the level of cortisol, as well as in the comparison between TG_PBM and G_PBM, in which there was a statistically significant difference for this same outcome (cortisol) and for the 6WTA outcome. The effects of the combination of PBM and aquatic exercise have positive effects on reducing pain intensity, disability, and cortisol levels, but its effects on other variables (6WTA and CK) are too small to be considered significant. Trial registration number: NCT03465228-April 3, 2019; retrospectively registered (ClinicalTrials.gov).

Correlation between pain, anthropometric measurements, stress and biochemical markers in women with low back pain

Aim: To analyze the associations between pain duration, pain levels, anthropometric measures, perceived stress and biochemical markers in women with low back pain. Materials & methods: Forty-two participants were submitted to body mass, height, abdominal circumference, cortisol and creatine kinase (CK) collections. Pain duration, pain levels and stress were analyzed through specific questionnaires. Results: There were positive correlations between abdominal circumference and body mass, duration of pain and age, abdominal circumference, CK and age, CK and BMI, CK and abdominal circumference, and CK and duration of pain (p < 0.05). Conclusion: The higher the level of tissue damage over the years, the greater the tendency for higher levels of low back pain perception. Central fat was related to greater load on the spine.

Exploring the relationship between chronic pain and cortisol levels in subjects with osteoarthritis: results from a systematic review of the literature

OBJECTIVE

Several reports in the literature have identified an association between cortisol levels and the presence of chronic pain in conditions such as rheumatoid arthritis, low back pain or whiplash. In contrast, few have examined the association of cortisol and pain in people with osteoarthritis (OA). The purpose of this systematic review was to verify the association between cortisol and pain in the OA population.

DESIGN

The databases MEDLINE, CINAHL, EMBASE were searched systematically for human studies written in English up to December 2018. Two researchers screened titles and abstracts against predefined inclusion criteria; a third resolved discrepancies. Articles were included if they measured the cortisol levels in adults with pain in the OA population. Methodological quality was assessed using Methodological Index for non-randomized Studies (MINORS) score.

RESULTS

Seven studies reporting on 415 patients were included in this review. The MINORS scale yielded mean scores of 8.6 of 16 and 17.5 of 24, for the cohort and case-control studies respectively. In general, the studies were of poor quality. A discrepancy of noteworthy associations between cortisol level comparison and pain was found.

CONCLUSIONS

This study shows that there is a discrepancy in the relationship between cortisol and pain dependent on how and when cortisol is measured. Evidence from three low-quality studies suggest increased cortisol levels in patients with pain but the conclusions have a high risk of bias. It was not possible to make a quantitative analysis comparing the relationship between cortisol and pain in the OA population.

The interaction between stress and chronic pain through the lens of threat learning

Stress and pain are interleaved at multiple levels - interacting and influencing each other. Both are modulated by psychosocial factors including fears, beliefs, and goals, and are served by overlapping neural substrates. One major contributing factor in the development and maintenance of chronic pain is threat learning, with pain as an emotionally-salient threat - or stressor. Here, we argue that threat learning is a central mechanism and contributor, mediating the relationship between stress and chronic pain. We review the state of the art on (mal)adaptive learning in chronic pain, and on effects of stress and particularly cortisol on learning. We then provide a theoretical integration of how stress may affect chronic pain through its effect on threat learning. Prolonged stress, as may be experienced by patients with chronic pain, and its resulting changes in key brain networks modulating stress responses and threat learning, may further exacerbate these impairing effects on threat learning. We provide testable hypotheses and suggestions for how this integration may guide future research and clinical approaches in chronic pain.

The Cortisol Awakening Response: A Feasibility Study Investigating the Use of the Area Under the Curve With Respect to Increase as an Effective Objective Measure of Tinnitus Distress

Purpose Tinnitus is a chronic medical condition that can result in distress, concentration difficulties, and clinical depression. An effective, objective measure of tinnitus distress does not currently exist. Endocrinal studies into the condition have been few, with those investigating the cortisol awakening response limited in scope. It was hypothesized that distressed individuals with tinnitus would awaken and be unable to effectively prepare for the day ahead due to a blunted cortisol response. Method Twenty individuals with varying tinnitus distress were compared with a control group (n = 10) in a pilot study, which measured salivary cortisol concentrations on awakening. Multiple exclusion variables were applied. Results In line with previous studies, total cortisol volume (as measured by area under the curve) was not found to be significantly different in the most distressed individuals with tinnitus, F(2, 26) = 0.254, p = .777ns. However, a separate measure of changing cortisol levels-the area under the curve with respect to increase (or AUC_i)-was found to be significantly less robust in those individuals reporting the most severe tinnitus distress, F(2, 26) = 7.671, p = .002. This indicates that fewer resources would be available to cope with the demands of the day ahead. Additionally, the AUC_i correlated negatively with tinnitus distress later the same day. Conclusions Relationships between proposed objective and self-reported components of self-reported tinnitus distress are considered, with some aspects of tinnitus distress more closely related to physiological mechanisms than others. It is suggested that, with further research, the cortisol awakening response (AUC_i) may be put forward as a credible objective biomarker of tinnitus distress.

Are perinatal factors associated with musculoskeletal pain across the lifespan? A systematic review with meta-analysis

BACKGROUND

Musculoskeletal conditions are common health issues with great impact on individuals. Although many factors have been associated with the development of musculoskeletal pain, such as perinatal factors, its aetiology is still poorly understood.

OBJECTIVE

To systematically investigate whether perinatal factors can increase the risk of having musculoskeletal pain across the lifespan.

METHODS

MEDLINE, CINAHL, Scopus, Web of Science and EMBASE databases were searched from their inception to December 2017. Descriptors used in our search strategy were related to "perinatal factors" and "musculoskeletal pain". There were no language, age, sex or date restrictions. Meta-analysis was used to pool the estimates of association between perinatal factors and musculoskeletal pain.

RESULTS

Among the six articles included in this systematic review, three were extracted for the meta-analysis. The pooled of three and two studies showed no association between chronic musculoskeletal pain and low birth weight (OR 1.8, 95% CI 0.9-3.8, I² = 0; n = 157) or pre-term birth (OR 0.5, 95% CI 0.0-4.5; I² = 78%; n = 374) in adults, respectively. Overall, the quality of evidence after applying the GRADE approach was very low across all the studies.

CONCLUSION

In adults, our meta-analysis showed no association between birth weight or pre-term birth and musculoskeletal pain, and the quality of the evidence was very low. Thus, the very low quality of evidence and limited number of studies do not suggest a direct clear association. Further high-quality longitudinal studies accounting for more relevant confounders are needed to better understand the complex mechanism that may operate between perinatal factors and musculoskeletal pain.

Fear of pain and cortisol reactivity predict the strength of stress-induced hypoalgesia

Background

Acute stress can have an effect on pain sensitivity, yet the direction of the effect – whether it is hypoalgesic or hyperalgesic – is mixed across studies. Moreover, which part of the stress response influences pain sensitivity is still unclear. In the current experimental study, we aim to examine the effect of acute stress on heat pain thresholds and pain tolerance levels in healthy participants, while taking into account individual differences in stress responses.

Methods

Forty‐two healthy participants were randomly assigned to either a well‐validated stress paradigm: the Maastricht Acute Stress Task (MAST; combining physical and psychological stressors) or to a nonstressful version of the task. Heat pain thresholds and tolerance levels were assessed at three times: prior to the MAST, immediately after the MAST during the presumed sympatho‐adrenal medullary (SAM) response, and 15 min after MAST to cover the presumed hypothalamus–pituitary–adrenal (HPA) axis response. Stress responses were assessed both subjectively and physiologically.

Results

We observed that the acute stress induction led to increased heat pain thresholds, an effect that was present only in participants showing a cortisol response following stress induction and only in the presumed HPA axis time window. The strength of this hypoalgesic effect was further predicted by the change in cortisol and by fear of pain levels.

Conclusions

Our findings indicate that the HPA axis – and not the autonomic – stress response specifically underlies this stress‐induced hypoalgesic effect, having important implications for clinical states with HPA axis dysfunctions.

Significance

This experimental study shows that an acute stress induction – that combines physical and psychological stressors – increases heat pain thresholds, but not tolerance in healthy participants. Furthermore, the magnitude of this stress‐induced hypoalgesic effect is predicted by cortisol reactivity and fear of pain, revealing specific involvement of the HPA axis stress system and interactions with pain‐related psychosocial aspects.

Chronic Pain and Chronic Stress: Two Sides of the Same Coin?

Pain and stress share significant conceptual and physiological overlaps. Both phenomena challenge the body's homeostasis and necessitate decision-making to help animals adapt to their environment. In addition, chronic stress and chronic pain share a common behavioral model of failure to extinguish negative memories. Yet, they also have discrepancies such that the final brain endophenotype of posttraumatic stress disorder, depression, and chronic pain appears to be different among the three conditions, and the role of the hypothalamic-pituitary-adrenal axis remains unclear in the physiology of pain. Persistence of either stress or pain is maladaptive and could lead to compromised well-being. In this brief review, we highlight the commonalities and differences between chronic stress and chronic pain, while focusing particularly on the central role of the limbic brain. We assess the current attempts in the field to conceptualize and understand chronic pain, within the context of knowledge gained from the stress literature. The limbic brain-including hippocampus, amygdala, and ventromedial pre-frontal cortex-plays a critical role in learning. These brain areas integrate incoming nociceptive or stress signals with internal state, and generate learning signals necessary for decision-making. Therefore, the physiological and structural remodeling of this learning circuitry is observed in conditions such as chronic pain, depression, and posttraumatic stress disorder, and is also linked to the risk of onset of these conditions.

Cortisol awakening response is blunted and pain perception is increased during menses in cyclic women

BACKGROUND AND AIMS

The incidence of menstrual symptoms is reported to be as high as 90% in cyclic women. These symptoms, including anxiety and pain, might be associated with cortisol, as its receptors are widely distributed in the brain areas associated with behavior. Therefore, the current study aimed to assess the cortisol awakening response (CAR) throughout the menstrual cycle and correlate it with pain perception and trait anxiety.

MATERIALS AND METHODS

CAR was assessed by measuring salivary cortisol at 0, 15, 30, and 60min following awakening in the same women (n=59, age 22.2±0.37years) at various stages of the menstrual cycle (menses, midcycle, luteal and premenstrual phases). Progesterone and estradiol concentrations were also determined in saliva samples to assess cyclic changes. Self-reported pain, trait anxiety, and menstrual symptoms were assessed by visual analog scale (VAS), state-trait anxiety inventory (STAI-T), and the Daily Record of Severity of Problems (DRSP), respectively.

RESULTS

Estradiol was significantly elevated during the midcycle period and remained high during the early luteal phase (p<0.05). Progesterone was increased during the luteal phase (p<0.05). Post-awakening cortisol values increased during midcycle, luteal phase, and premenstrual phase (p<0.05, classical CAR), but not during the menses (p>0.05, blunted or flat CAR). Positive and significant correlations were found between cortisol and estradiol (R²=0.322; p=0.000), cortisol and progesterone (R²=0.156; p=0.000), and estradiol and progesterone (R²=0.349; p=0.001). Premenstrual symptom scores were higher in the menses and premenstrual phases than in the midcycle and luteal phases (p<0.001). Pain perception was the highest during the menses followed by the premenstrual phase (p<0.01).

CONCLUSIONS

CAR was blunted during the menses, suggesting that cortisol might play a phase-specific role in the regulation of the cycle. Additionally, premenstrual symptoms, including pain, were more severe when ovarian steroid levels reduced (i.e., menses and the premenstrual phase).

The Role of Stress Regulation on Neural Plasticity in Pain Chronification

Pain, especially chronic pain, is one of the most common clinical symptoms and has been considered as a worldwide healthcare problem. The transition from acute to chronic pain is accompanied by a chain of alterations in physiology, pathology, and psychology. Increasing clinical studies and complementary animal models have elucidated effects of stress regulation on the pain chronification via investigating activations of the hypothalamic-pituitary-adrenal (HPA) axis and changes in some crucial brain regions, including the amygdala, prefrontal cortex, and hippocampus. Although individuals suffer from acute pain benefit from such physiological alterations, chronic pain is commonly associated with maladaptive responses, like the HPA dysfunction and abnormal brain plasticity. However, the causal relationship among pain chronification, stress regulation, and brain alterations is rarely discussed. To call for more attention on this issue, we review recent findings obtained from clinical populations and animal models, propose an integrated stress model of pain chronification based on the existing models in perspectives of environmental influences and genetic predispositions, and discuss the significance of investigating the role of stress regulation on brain alteration in pain chronification for various clinical applications.

Adrenal fatigue does not exist: a systematic review

BACKGROUND

The term "adrenal fatigue" ("AF") has been used by some doctors, healthcare providers, and the general media to describe an alleged condition caused by chronic exposure to stressful situations. Despite this, "AF" has not been recognized by any Endocrinology society, who claim there is no hard evidence for the existence. The aim of this systematic review is to verify whether there is substantiation for "AF".

METHODS

A systematic search was performed at PUBMED, MEDLINE (Ebsco) and Cochrane databases, from the beginning of the data until April 22nd, 2016. Searched key words were: "adrenal" + "fatigue", "adrenal" + "burnout", "adrenal" + "exhaustion", "hypoadrenia", "burnout" + "cortisol", "fatigue" + "cortisol", "clinical" + "burnout", "cortisol" + "vitalility", "adrenal" + "vitality", and "cortisol" + "exhaustion". Eligibility criteria were: (1) articles written in English, (2) cortisol profile and fatigue or energy status as the primary outcome, (3) performed tests for evaluating the adrenal axis, (4) absence of influence of corticosteroid therapy, and (5) absence of confounding diseases. Type of questionnaire to distinct fatigued subjects, population studied, tests performed of selected studies were analyzed.

RESULTS

From 3,470 articles found, 58 studies fulfilled the criteria: 33 were carried in healthy individuals, and 25 in symptomatic patients. The most assessed exams were "Direct Awakening Cortisol" (n = 29), "Cortisol Awakening Response" (n = 27) and "Salivary Cortisol Rhythm" (n = 26).

DISCUSSION

We found an almost systematic finding of conflicting results derived from most of the studies methods utilized, regardless of the validation and the quality of performed tests. Some limitations of the review include: (1) heterogeneity of the study design; (2) the descriptive nature of most studies; (3) the poor quality assessment of fatigue; (4) the use of an unsubstantiated methodology in terms of cortisol assessment (not endorsed by endocrinologists); (5) false premises leading to an incorrect sequence of research direction; and, (6) inappropriate/invalid conclusions regarding causality and association between different information.

CONCLUSION

This systematic review proves that there is no substantiation that "adrenal fatigue" is an actual medical condition. Therefore, adrenal fatigue is still a myth.