Jana Strahler

Intra-individual psychological and physiological responses to acute laboratory stressors of different intensity

OBJECTIVES The phenomenon of stress is understood as a multidimensional concept which can be captured by psychological and physiological measures. There are various laboratory stress protocols which enable stress to be investigated under controlled conditions. However, little is known about whether these protocols differ with regard to the induced psycho-physiological stress response pattern. METHODS In a within-subjects design, 20 healthy young men underwent four of the most common stress protocols (Stroop test [Stroop], cold pressor test [CPT], Trier Social Stress Test [TSST], and bicycle ergometer test [Ergometer]) and a no-stress control condition (rest) in a randomized order. For the multidimensional assessment of the stress response, perceived stress, endocrine and autonomic biomarkers (salivary cortisol, salivary alpha-amylase, and heart rate) were obtained during the experiments. RESULTS All stress protocols evoked increases in perceived stress levels, with the highest levels in the TSST, followed by Ergometer, Stroop, and CPT. The highest HPA axis response was found in the TSST, followed by Ergometer, CPT, and Stroop, whilst the highest autonomic response was found in the Ergometer, followed by TSST, Stroop, and CPT. CONCLUSIONS These findings suggest that different stress protocols differentially stimulate various aspects of the stress response. Physically demanding stress protocols such as the Ergometer test appear to be particularly suitable for evoking autonomic stress responses, whereas uncontrollable and social-evaluative threatening stressors (such as the TSST) are most likely to elicit HPA axis stress responses. The results of this study may help researchers in deciding which stress protocol to use, depending on the individual research question.

Biomarkers of stress in behavioural medicine.

Purpose of review In recent years, a growing interest has emerged in behavioural medicine to examine the role of acute and chronic stress as a predisposing and contributing factor to physical health and illness. For a deeper understanding of these associations, research is in need of biological markers for alterations in biological stress systems. This review will summarize a selection of important recent findings in this area of research. Recent findings We will focus on essential peripheral stress-sensitive physiological systems, that is, the hypothalamic–pituitary–adrenal axis, the autonomic nervous system, and the immune system. We will present findings on commonly used stress biomarkers (cortisol, alpha-amylase, pro-inflammatory cytokines) regarding alterations in basal activity and stress-dependent reactivity in these systems, and discuss selected findings on intervention-induced changes of these biomarkers. Summary This review will highlight new developments and guide readers in their choice of suitable study designs and outcomes in behavioural medicine. The reviewed studies included here encourage optimism that the employment of stress biomarkers in behavioural medicine has the potential to significantly improve our understanding of physical health and illness.

Genetic contributions to acute autonomic stress responsiveness in children.

Identification of genetic factors that influence stress reactivity is important in order to link environmental demands, particularly adversity to disease outcome. There is ample literature on genetic contribution to the endocrine stress response, while evidence for genetic contribution to individual differences in autonomic nervous system function is sparse and produced conflicting results. Here, we investigated the influence of two polymorphisms in the Catechol-o-methyltransferase (COMT) and serotonin transporter (5-HTT; SCL6A4) gene. We examined the autonomic stress response to the Trier Social Stress Test for Children in 115 children. Salivary α-amylase (sAA) was obtained prior to the stressor and repeatedly during recovery as a marker of autonomic reactivity. Furthermore, heart rate (HR) and heart rate variability (HRV) were monitored continuously. We found differences in ANS stress response associated with each polymorphism (all p<.05). Children with the L variant of 5-HTTLPR showed a higher increase and sharper recovery of sAA in response to stress than those with S variants. For HR, we found differences associated with COMT, i.e. children carrying at least one met allele showed lower mean HR increase and slower HR recovery in response to the stressor compared to those with two val alleles (p<.001) as well as a significant decrease in heart rate variability (p<.05). Our findings indicate that these two polymorphisms do indeed influence the ANS response to stress. This study provides further evidence for the crucial role of genetic factors in the modulation of differences in the acute stress response during childhood.

Stress exacerbates pain in the everyday lives of women with fibromyalgia syndrome—The role of cortisol and alpha-amylase

OBJECTIVE Although fibromyalgia syndrome (FMS) is a chronic condition, its cardinal symptom pain is known to fluctuate over the day. Stress has often been claimed to exacerbate pain; however, there is barely any evidence on whether or not this is true on a day-to-day basis (and, alternatively, on whether pain leads to increased stress levels). Using an ecologically valid measurement design, we tested whether and how stress and pain are intertwined in participants with FMS. We additionally examined the role of the two major stress-responsive systems, the hypothalamic-pituitary-adrenal axis and the autonomic nervous system, as potential mediators of this relationship. METHODS An ambulatory assessment study was conducted over the course of 14 days. On each day, 32 females with FMS provided six diary entries on momentary stress and pain levels. Saliva samples were collected at the same time points to determine cortisol and alpha-amylase as indicators of stress-responsive systems. RESULTS Higher stress at a given measurement time point was associated with higher reported pain levels at the subsequent time point (UC=1.47, p<0.001), but not vice versa (UC<0.01, p=0.179). The stress-pain relationship was neither mediated by momentary cortisol nor by alpha-amylase; however, momentary cortisol was independently associated with momentary pain (UC=0.27, p=0.009). CONCLUSION Stress seems to be a powerful exacerbating factor for pain as experienced by patients with FMS in their everyday lives. Cortisol may be involved in the diurnal fluctuation of pain levels in patients with FMS. Future studies should identify relevant daily stressors in persons with FMS and scrutinize the mechanisms underlying the cortisol-pain relationship.

The effects of music listening on pain and stress in the daily life of patients with fibromyalgia syndrome

Music listening is associated with both pain- and stress-reducing effects. However, the effects of music listening in daily life remain understudied, and the psycho-biological mechanisms underlying the health-beneficial effect of music listening remain unknown. We examined the effects of music listening on pain and stress in daily life in a sample of women with fibromyalgia syndrome (FMS; i.e., a condition characterized by chronic pain) and investigated whether a potentially pain-reducing effect of music listening was mediated by biological stress-responsive systems. Thirty women (mean age: 50.7 ± 9.9 years) with FMS were examined using an ecological momentary assessment design. Participants rated their current pain intensity, perceived control over pain, perceived stress level, and music listening behavior five times per day for 14 consecutive days. At each assessment, participants provided a saliva sample for the later analysis of cortisol and alpha-amylase as biomarkers of stress-responsive systems. Hierarchical linear modeling revealed that music listening increased perceived control over pain, especially when the music was positive in valence and when it was listened to for the reason of ‘activation’ or ‘relaxation’. In contrast, no effects on perceived pain intensity were observed. The effects of music listening on perceived control over pain were not mediated by biomarkers of stress-responsive systems. Music listening in daily life improved perceived control over pain in female FMS patients. Clinicians using music therapy should become aware of the potential adjuvant role of music listening in daily life, which has the potential to improve symptom control in chronic pain patients. In order to study the role of underlying biological mechanisms, it might be necessary to use more intensive engagement with music (i.e., collective singing or music-making) rather than mere music listening.

Norepinephrine and epinephrine responses to physiological and pharmacological stimulation in chronic fatigue syndrome

Chronic fatigue syndrome (CFS) is characterized by fatigue lasting 6 months or longer. CFS has been associated with a disturbed (re-)activity of the autonomic nervous system. However, the sympathetic adrenomedulla (SAM) remains under-examined in CFS. To investigate SAM reactivity, we implemented a submaximal cycle ergometry (ERGO) and a pharmacological test (Insulin Tolerance Test, ITT) in 21 CFS patients and 20 age-, sex-, and BMI-matched controls. Plasma norepinephrine and epinephrine were collected once before and twice after the tests (+10/+20, and +30 min). Lower baseline levels and attenuated responses of epinephrine to the ERGO were found in CFS patients compared to controls, while the groups did not differ in their responses to the ITT. To conclude, we found evidence of altered sympathetic-neural and SAM reactivity in CFS. Exercise stress revealed a subtle catecholaminergic hyporeactivity in CFS patients. It is conceivable that inadequate catecholaminergic responses to physical exertion might contribute to CFS symptoms.

Acute psychosocial stress induces differential short-term changes in catecholamine sensitivity of stimulated inflammatory cytokine production.

BACKGROUND We have previously shown that psychosocial stress induces acute changes in glucocorticoid (GC) sensitivity of pro-inflammatory cytokine production. However, hormones of the sympathetic adrenal medullary system complement endocrine regulation of inflammatory responses. The current study therefore aimed at investigating the effects of repeated acute stress exposure on catecholamine sensitivity of inflammatory cytokine production. METHODS Twenty healthy male participants were subjected to the Trier Social Stress Test on two consecutive days. Blood samples were taken before and repeatedly after stress. Whole blood was stimulated with lipopolysaccharide and incubated with increasing concentrations of epinephrine (E) and norepinephrine (NE) for 18h. Tumor-necrosis-factor (TNF) alpha and interleukin (IL)-6 were measured in culture supernatants. RESULTS Overall, incubation with E and NE induced dose-dependent suppression of TNF-alpha (NE: F=77.66, p<.001; E: F=63.38, p<.001), and IL-6 production (NE: F=28.79, p<.001; E: F=24.66, p<.001). Acute stress exposure resulted in reduced sensitivity of TNF-alpha (NE: F=6.36, p<.001; E: F=4.86, p=.005), but not IL-6 (NE: F=1.07, p=.38; E: F=0.88, p=.50) to the inhibitory signals of E and NE. No evidence of habituation of these effects was found (all p⩾.22). CONCLUSIONS The present findings extend our knowledge on changes in inflammatory target tissue sensitivity in response to acute psychosocial stress from glucocorticoid-dependent effects to catecholamine-dependent effects. Stress-induced decreases in catecholamine sensitivity thereby suggest intracellular processes aiding in maintaining a healthy endocrine-immune interplay. Longitudinal studies will have to investigate the processes leading from a supposedly beneficial short-term catecholamine resistance in response to acute stress to basal catecholamine resistance observed in relation to negative health outcomes.

Lower stress system activity and higher peripheral inflammation in competitive ballroom dancers.

Although regular physical exercise is beneficial for health, competitive ballroom dancers anecdotally report increased disease susceptibility. This study aims to uncover possible biological mechanisms and pathways that may lead to higher disease susceptibility in a population of otherwise healthy young athletes. Experienced ballroom dancers and healthy controls provided blood and saliva samples in order to assess diurnal cortisol and alpha-amylase (sAA) output as well as inflammatory parameters interleukin (IL)-6 and C-reactive protein (CRP). We found diurnal cortisol and sAA output to be significantly lower in dancers. Additionally, higher levels in IL-6 but not in CRP were shown in dancers. Dancers described themselves as being more anxious and reported more physical health complaints. Competitive ballroom dancers show evidence for hypoactivity in stress systems and peripheral inflammation along with more self-reported physical complaints. Therefore, competitive ballroom dancing represents a chronic stressor that can lead to important functional consequences. It remains to be investigated whether these alterations are causally related to health.

Hormonal, metabolic, and cardiorespiratory responses of young and adult athletes to a single session of high-intensity cycle exercise.

This study aimed to determine the effects of a single high-intensity interval training (HIIT) session on salivary cortisol (SC) levels, physiological responses, and performance in trained boys and men. Twenty-three boys (11.5 ± 0.8 years) and 25 men (29.7 ± 4.6 years) performed HIIT (4 consecutive Wingate Anaerobic Tests). SC in boys and men increased after HIIT from 5.55 ± 3.3 nmol/l to 15.13 ± 9.7 nmol/l (+173%) and from 7.07 ± 4.7 nmol/l to 19.19 ± 12.7 nmol/l (+171%), respectively (p < .01). Pretest SC as well as posttest changes were comparable in both groups (both p < .01). Peak blood lactate concentration was significantly lower in boys (12.6 ± 3.5 mmol/l) than in men (16.3 ± 3.1 mmol/l; p < .01). Throughout the HIIT, mean heart rates in boys were higher (p < .001) but relative peak oxygen uptake (ml·min-1·kg-1; p < .05) and performance were lower (p < .001) in boys than in men. HIIT in young athletes is associated with a higher activation of the hormonal stress axis than other types of exercise regimes as described in the literature. This study is the first to show a pronounced SC increase to HIIT in trained boys accompanied by elevated levels of blood lactate concentrations and heart rate suggesting a high cardio-respiratory, metabolic, and hormonal response to HIIT in 11-year-old boys.

The stress-reducing effect of music listening varies depending on the social context.

OBJECTIVE Given that music listening often occurs in a social context, and given that social support can be associated with a stress-reducing effect, it was tested whether the mere presence of others while listening to music enhances the stress-reducing effect of listening to music. METHODS A total of 53 participants responded to questions on stress, presence of others, and music listening five times per day (30min after awakening, 1100h, 1400h, 1800h, 2100h) for seven consecutive days. After each assessment, participants were asked to collect a saliva sample for the later analysis of salivary cortisol (as a marker for the hypothalamic-pituitary-adrenal axis) and salivary alpha-amylase (as a marker for the autonomic nervous system). RESULTS Hierarchical linear modeling revealed that music listening per se was not associated with a stress-reducing effect. However, listening to music in the presence of others led to decreased subjective stress levels, attenuated secretion of salivary cortisol, and higher activity of salivary alpha-amylase. When listening to music alone, music that was listened to for the reason of relaxation predicted lower subjective stress. CONCLUSION The stress-reducing effect of music listening in daily life varies depending on the presence of others. Music listening in the presence of others enhanced the stress-reducing effect of music listening independently of reasons for music listening. Solitary music listening was stress-reducing when relaxation was stated as the reason for music listening. Thus, in daily life, music listening can be used for stress reduction purposes, with the greatest success when it occurs in the presence of others or when it is deliberately listened to for the reason of relaxation.