Stress-Induced Allodynia – Evidence of Increased Pain Sensitivity in Healthy Humans and Patients with Chronic Pain after Experimentally Induced Psychosocial Stress

Background: Experimental stress has been shown to have analgesic as well as allodynic effect in animals. Despite the obvious negative influence of stress in clinical pain conditions, stress-induced alteration of pain sensitivity has not been tested in humans so far. Therefore, we tested changes of pain sensitivity using an experimental stressor in ten female healthy subjects and 13 female patients with fibromyalgia. Methods: Multiple sensory aspects of pain were evaluated in all participants with the help of the quantitative sensory testing protocol before (60 min) and after (10 and 90 min) inducing psychological stress with a standardized psychosocial stress test (“Trier Social Stress Test”). Results: Both healthy subjects and patients with fibromyalgia showed stress-induced enhancement of pain sensitivity in response to thermal stimuli. However, only patients showed increased sensitivity in response to pressure pain. Conclusions: Our results provide evidence for stress-induced allodynia/hyperalgesia in humans for the first time and suggest differential underlying mechanisms determining response to stressors in healthy subjects and patients suffering from chronic pain. Possible mechanisms of the interplay of stress and mediating factors (e.g. cytokines, cortisol) on pain sensitivity are mentioned. Future studies should help understand better how stress impacts on chronic pain conditions

Associations between jet lag and cortisol diurnal rhythms after domestic travel.

Objective: Millions of adults in the United States travel abruptly across time zones each year. Nevertheless, the impact of traveling over relatively short distances (across 3 or fewer time zones) on diurnal patterning of typical physiological response patterns has yet to be studied in a large, epidemiological sample. Design: The current research focuses on 764 middle-aged men comparing variations in diurnal cortisol regulation based on number of time zones traveled eastward or westward the day before. Main Outcome Measure: Participants provided samples of salivary cortisol at waking, 30-min postwaking, 10 a.m., 3 p.m., and bedtime. Results: Eastward travel was associated with a steeper salivary cortiso

Influence of prenatal psychosocial stress on cytokine production in adult women

The aim of the present study was to determine the association between prenatal stress and immune function in human adults. Peripheral blood mononuclear cells (PBMCs) from 34 healthy young women whose mothers experienced major negative life events during their pregnancy (Prenatal Stress, PS group, mean age 25, SD 4.34 years), and from a female comparison group (n¼28, CG, mean age 24 3.40 years), were stimulated with phytohemagglutinin (PHA), and subsequent cytokine production was measured. A bias for T-helper 2 (Th2) cytokine production due to an overproduction of IL-4 relative to IFN-g after PHA stimulation was observed in PS subjects. In addition, IL-6 and IL-10 were also significantly elevated. To the best of our knowledge, this study is the first to suggest a direct association between prenatal stress exposure and alterations in immune parameters in adult women

Negative emotionality, depressive symptoms and cortisol diurnal rhythms: 2 Analysis of a community sample of middle-aged males

Prior research suggests that individuals with particular personality traits, like negative emotionality, are at 32 greater risk for adverse health outcomes. Despite bivariate associations between negative emotionality, 33 depressive symptoms and the hypothalamic pituitary adrenal axis (HPA axis), few studies have sought to 34 understand the biological pathways through which negative emotionality, depressive symptomatology and 35 cortisol-one of the primary hormonal products of the HPA axis-are associated. The present study explored 36 whether negative emotionality influenced cortisol dysregulation through current depressive symptomatol-37 ogy and whether negative emotionality served as a moderator of the relationship between depressive 38 symptoms and cortisol. In the community-based Vietnam Era Twin Study of Aging, 783 male twins completed 39 two days of cortisol saliva sampling in their natural environments. Three measures of cortisol were analyzed: 40 waking levels, the cortisol awakening response, and the peak to bed slope. Depressive symptoms significantly 41 mediated the associations between negative emotionality and the peak to bed slope. A 2-way interaction 42 between depressive symptoms and negative emotionality was significant for the peak to bed slope and for 43 waking levels of cortisol. Exploration of the interactions illustrated that depressive symptoms only affected 44 cortisol slopes at average or high levels of negative emotionality and only affected waking levels at low levels 45 of negative emotionality. Negative emotionality and depressive symptoms were not related to the cortisol 46 awakening response. This is the first study to find indirect associations between negative emotionality and 47 peak to bed cortisol slopes through depressive symptoms. These findings illustrate the complex interplay 48 between personality characteristics, depressive symptoms and different indices of the cortisol diurnal 49 rhythm. 5

Salivary cortisol and prefrontal cortical thickness in middle-aged men: A twin study.

Although glucocorticoid receptors are highly expressed in the prefrontal cortex, the hippocampus remains the predominant focus in the literature examining relationships between cortisol and brain. We examined phenotypic and genetic associations of cortisol levels with the thickness of prefrontal and anterior cingulate cortex regions, and with hippocampal volume in a sample of 388 middle-aged male twins who were 51-59 years old. Small but significant negative phenotypic associations were found between cortisol levels and the thickness of left dorsolateral (superior frontal gyrus, left rostral middle frontal gyrus) and ventrolateral (pars opercularis, pars triangularis, pars orbitalis) prefrontal regions, and right dorsolateral (superior frontal gyrus) and medial orbital frontal cortex. Most of the associations remained significant after adjusting for general cognitive ability, cardiovascular risk factors, and depression. Bivariate genetic analyses suggested that some of the associations were primarily accounted for by shared genetic influences; that is, some of the genes that tend to result in increased cortisol levels also tend to result in reduced prefrontal cortical thickness. Aging has been associated with reduced efficiency of hypothalamic-pituitary-adrenal function, frontal lobe shrinkage, and increases in health problems, but our present data do not allow us to determine the direction of effects. Moreover, the degree or the direction of the observed associations and the extent of their shared genetic underpinnings may well change as these individuals age. Longitudinal assessments are underway to elucidate the direction of the associations and the genetic underpinnings of longitudinal phenotypes for changes in cortisol and brain morphology