Changes in stress pathways as a possible mechanism of aerobic exercise training on brain health: a scoping review of existing studies

Physical activity (PA) in the form of aerobic exercise (AE) preserves and improves neurocognitive function across the lifespan. However, a mechanistic understanding of the pathways by which aerobic exercise impacts brain health is still lacking, particularly with respect to stress-related pathways. One mechanistic hypothesis is that AE improves neurocognitive health in part by modifying circulating levels of stress-related hormones and signaling factors associated with the hypothalamic-pituitary-adrenal (HPA) axis and autonomic nervous system (ANS), as commonly measured by the biomarkers cortisol (CORT) and salivary α-amylase (sAA). Thus, this hypothesis predicts that changes in stress biomarkers, such as CORT and sAA, are possible explanatory pathways mediating the positive effects of AE on neurocognitive health. In the present review article, we provide a summary of available studies examining the possibility that exercise-induced changes to stress biomarkers could partly account for exercise-related improvements in neurocognitive health. Our review indicates that despite the intuitive appeal of this hypothesis, there is insufficient evidence available to conclude that chronic and habitual AE affects neurocognitive health by altering stress biomarker pathways. The cross-sectional nature of the majority of reviewed studies highlights the need for well-controlled studies to adequately test this hypothesis.

How is music listening purpose related to stress recovery? - two preliminary studies in men and women

Introduction

Studies have suggested that listening to music can reduce psychological and biological responses to a stressor. However, it is unclear whether music has the same effect on stress recovery. According to field studies, people commonly use music in daily life for the specific purpose of relaxation. We explored whether individuals who generally use music for relaxation purposes show improved recovery from an acute stressor.

Methods

In two independent studies, twenty-seven healthy female participants (Mage = 24.07) (Study 1) and twenty-one healthy male participants (Mage = 23.52) (Study 2) were separated into two groups based on their frequency of using music for relaxation purposes (low vs. high). All participants underwent a lab-based psychosocial stress test. Subjective stress levels were measured using visual analogue scales. Salivary cortisol and salivary alpha-amylase were measured to assess endocrine and autonomic stress responses, respectively. Subjective stress levels and saliva samples were measured nine times throughout the stress induction and recovery procedure. Chronic stress levels were assessed using the Perceived Stress Scale and the Screening Scale of Chronic Stress.

Results

No significant differences were observed in subjective stress levels, salivary alpha-amylase activity, or cortisol concentration between the two groups in either of the two studies. Further analyses revealed that among male participants, increased use of music for relaxation purposes was related to more chronic stress levels (t (10.46) = 2.45, p = 0.03, r = 0.60), whereas female participants exhibited a trend in the opposite direction (t (13.94) = -1.92, p = 0.07, r = 0.46).

Discussion

Contrary to our expectations, the results indicate that habitual music listening for relaxation purposes is not associated with improved recovery from a stressor. However, due to the small sample size, future exploration is necessary to enhance the statistical power of the results of the study.

ForDigitStress: presentation and evaluation of a new laboratory stressor using a digital job interview-scenario

Introduction

Since the COVID-19 pandemic, working environments and private lives have changed dramatically. Digital technologies and media have become more and more important and have found their way into nearly all private and work environments. Communication situations have been largely relocated to virtual spaces. One of these scenarios is digital job interviews. Job interviews are usually-also in the non-digital world-perceived as stressful and associated with biological stress responses. We here present and evaluate a newly developed laboratory stressor that is based on a digital job interview-scenario.

Methods

N = 45 healthy people participated in the study (64.4% female; mean age: 23.2 ± 3.6 years; mean body mass index = 22.8 ± 4.0 kg/m²). Salivary alpha-amylase (sAA) and cortisol were assessed as measures for biological stress responses. Furthermore, perceived stress was rated at the time points of the saliva samplings. The job interviews lasted between 20 and 25 min. All materials, including instructions for the experimenter (i.e., the job interviewer) and the data set used for statistical analysis, as well as a multimodal data set, which includes further measures, are publicly available.

Results

Typical subjective and biological stress-response patterns were found, with peak sAA and perceived stress levels observed immediately after the job interviews and peak cortisol concentrations 5 min afterwards. Female participants experienced the scenario as more stressful than male participants. Cortisol peaks were higher for participants who experienced the situation as a threat in comparison to participants who experienced it as a challenge. Associations between the strength of the stress response with further person characteristics and psychological variables such as BMI, age, coping styles, and personality were not found.

Discussion

Overall, our method is well-suited to induce biological and perceived stress, mostly independent of person characteristics and psychological variables. The setting is naturalistic and easily implementable in standardized laboratory settings.

Comparison of distraction techniques using salivary biomarkers during local anaesthesia administration in children aged 3-5 years: A clinical study

Aim

In paediatric dentistry, pain is adversely influenced by a child's level of anxiety. Ironically, the most common form of pain control used in dentistry, local anaesthesia, can itself produce anxiety. One of the techniques to overcome a child's anxiety is using distraction. The aim of the present study was to evaluate the effectiveness of distraction techniques, i.e. audio distraction (AD) and audio-visual distraction (AVD) by measuring salivary stress biomarker (salivary cortisol and salivary alpha-amylase) levels in 3-5 year-old children.

Materials and Methods

Forty children aged 3-5 years were divided randomly into two groups; (Group I = AD, Group II = AVD). Cotton pellets were placed in the lingual vestibule to collect a sample of saliva. Children were then asked to wear overhead phones in the AD group, connected to a phone, and rhymes were played. In AVD, a cartoon movie was shown to the children using AV glasses. Simultaneously, local anaesthesia was administrated to children, after which another saliva sample was collected. Biomarker estimation was done using ELISA. Fisher's exact test was used for statistical analysis.

Results

Statistically significant results were seen with Group II compared to Group I (cortisol-P = 0.009; salivary alpha-amylase-P = 0.03).

Conclusion

Both distraction techniques are effective in reducing stress but compared to AD, AVD is more efficacious.

Cananga odorata Aromatherapy Reduces Anxiety in Unexperienced Patients Hospitalized for Interventional Neuroradiology Procedures: A Randomized Control Trial

The hospitalization and the unfamiliar experiences of patients in interventional radiology procedures cause a moderate to high levels of anxiety. This study was aimed to evaluate the anxiolytic effect of Cananga odorata essential oil (COE) aromatherapy in unexperienced patients hospitalized for interventional neuroradiology (INR) procedures. Forty-four patients admitted for their first INR procedure were randomly divided into COE and placebo control groups. COE or distilled water was dropped onto 2 pieces of mulberry paper and attached to the participant's gown at the shoulder level overnight. The main outcomes were observed from the morning salivary cortisol levels and salivary alpha-amylase activity after intervention. The Thai version of Spielberger State-Trait Anxiety Inventory (STAI) and the vital signs (blood pressure and heart rate) were also assessed before and after COE intervention as the secondary outcome. The demographic and baseline data of both groups did not show any significant difference. After intervention, COE group had a significantly lower salivary alpha-amylase activity than placebo control group. The post-intervention scores of Trait (STAI-T) and State (STAI-S) anxiety were significantly less than those of baseline in both groups. Interestingly, the COE group had a greater percentage reduction on STAI-T after intervention than placebo control group. No significant difference was observed in other outcomes. In addition, the salivary alpha-amylase activity was weak but showed significant correlation with STAI anxiety scores. This study indicates that COE aromatherapy reduces the saliva alpha amylase activity and STAI-T anxiety in unexperienced patients hospitalized for INR procedures.

The Effect of Dental Treatments in Caries Management on Stress and Salivary Protein Levels

A great burden is put on healthcare systems by dental caries and understanding patients’ treatment needs is of utmost importance. The aim of this pre−post study was to assess dental anxiety and the psychological stress induced by two different types of dental treatment (prophylaxis and cavity preparation), by combining psychometric evaluations with salivary biomarkers, in a group of 28 schoolchildren presenting in a university clinic. Pre- and post-treatment unstimulated whole saliva was collected and levels of cortisol, alpha-amylase (sAA) and total protein content were measured. The State−Trait Anxiety Inventory for Children and the Frankl Behaviour Rating Scale (FBRS) were applied. Statistical analysis was performed using the Stata/IC 16 (StataCorp) programme. All salivary parameters showed strong positive correlations between pre- and post-treatment levels. Post-treatment, salivary cortisol decreased (p = 0.008, paired t-test), sAA did not change significantly (p = 0.572, sign test), while the sAA/cortisol ratio (AOC) increased (p = 0.036, sign test). There were no correlations between state and trait anxiety levels. State anxiety scores registered significantly higher values for children with an FBRS score of 3 compared with a score of 4 (p < 0.001, unpaired t-test). The post-treatment decrease in the salivary cortisol level was higher for prophylaxis compared with the cavity preparation group (p = 0.024, t-test). These results demonstrate that sAA and cortisol levels are altered differently by psychological stress induced by two different types of dental treatment.

Neuroendocrine Response and State Anxiety Due to Psychosocial Stress Decrease after a Training with Subject's Own (but Not Another) Virtual Body: An RCT Study

Previous research involving healthy participants has reported that seeing a moving virtual body from the first person perspective induces the illusion of ownership and agency over that virtual body. When a person is sitting and the virtual body runs, it is possible to measure physiological, behavioral and cognitive reactions that are comparable to those that occur during actual movement. Capitalizing on this evidence, we hypothesized that virtual training could also induce neuroendocrine effects that prompt a decreased psychosocial stress response, as occurs after physical training. While sitting, 26 healthy young adults watched a virtual avatar running for 30 min from the first person perspective (experimental group), while another 26 participants watched the virtual body from the third person perspective (control group). We found a decreased salivary alpha-amylase concentration (a biomarker for the stress response) after the virtual training among the experimental group only, as well as a decreased subjective feeling of state anxiety (but no difference in heart rate). We argue that the virtual illusion of a moving body from the first person perspective can initiate a cascade of events, from the perception of the visual illusion to physiological activation that triggers other biological effects, such as the neuroendocrine stress response.

No evidence for a modulating effect of continuous transcutaneous auricular vagus nerve stimulation on markers of noradrenergic activity

Although transcutaneous auricular vagus nerve stimulation (taVNS) is thought to increase central noradrenergic activity, findings supporting such mechanism are scarce and inconsistent. This study aimed to investigate whether taVNS modulates indirect markers of phasic and tonic noradrenergic activity. Sixty-six healthy participants performed a novelty auditory oddball task twice on separate days: once while receiving taVNS (left cymba concha), once during sham (left earlobe) stimulation. To maximize potential effects, the stimulation was delivered continuously (frequency: 25 Hz; width: 250 μs) at an intensity individually calibrated to the maximal level below pain threshold. The stimulation was administered 10 min before the oddball task and maintained throughout the session. Event-related pupil dilation (ERPD) to target stimuli and pre-stimulus baseline pupil size were assessed during the oddball task as markers of phasic and tonic noradrenergic activity, respectively. Prior to and at the end of stimulation, tonic pupil size at rest, cortisol, and salivary alpha-amylase were assessed as markers of tonic noradrenergic activity. Finally, we explored the effect of taVNS on cardiac vagal activity, respiratory rate, and salivary flow rate. Results showed a greater ERPD to both target and novelty compared to standard stimuli in the oddball task. In contrast to our hypotheses, taVNS did not impact any of the tested markers. Our findings strongly suggest that continuous stimulation of the cymba concha with the tested stimulation parameters is ineffective to increase noradrenergic activity via a vagal pathway.

Evaluation of Salivary Alpha-Amylase Levels for Determining Stress Variations in Patients Undergoing Spinal Anesthesia for Infra-Umbilical Surgery

Aims and Objectives:

To evaluate salivary alpha-amylase (sAA) levels for determining stress variations in patients undergoing spinal anesthesia for infra-umbilical surgery.

Materials and Methods:

One hundred and twenty subjects (age 18–65 years) planned for infra-umbilical surgery under spinal anesthesia were included and allocated to Groups A and B ensuring age and sex matching. In both groups, sAA levels (S1 to S4) were assessed sequentially at different times (E1 to E4). S1 and S2 were collected on the evening before surgery (E1) and in the preoperative room on the day of surgery (E2), respectively. Thereafter, in Group A, S3 and S4 were collected before (E3) and 15 min after spinal anesthesia (E4), following which intravenous Midazolam was given. In Group B, intravenous Midazolam was administered first, S3 was collected 5 min later (E3), spinal anesthesia was administered and S4 was collected after15 min (E4).

Results:

In both groups, sAA levels showed a mild increase from E1 to E2 (not significant). Thereafter from E2 to E3 and E3 to E4, a significant sharp rise in sAA levels in Group A and a significantly acute decline in Group B was noted. Mean sAA levels in Group A were higher as compared to group B (P < 0.005) in E3 and E4.

Conclusion:

Sequential documentation of increase in sAA levels in our study, starting with the baseline levels, presents a comprehensive report of the stress that the patients experience during preoperative period and reinforces the need of anxiolytic before spinal anesthesia.

Effects of transcutaneous auricular vagus nerve stimulation on reversal learning, tonic pupil size, salivary alpha-amylase, and cortisol

This study investigated whether transcutaneous auricular vagus nerve stimulation (taVNS) enhances reversal learning and augments noradrenergic biomarkers (i.e., pupil size, cortisol, and salivary alpha-amylase [sAA]). We also explored the effect of taVNS on respiratory rate and cardiac vagal activity (CVA). Seventy-one participants received stimulation of either the cymba concha (taVNS) or the earlobe (sham) of the left ear. After learning a series of cue-outcome associations, the stimulation was applied before and throughout a reversal phase in which cue-outcome associations were changed for some (reversal), but not for other (distractor) cues. Tonic pupil size, salivary cortisol, sAA, respiratory rate, and CVA were assessed at different time points. Contrary to our hypothesis, taVNS was not associated with an overall improvement in performance on the reversal task. Compared to sham, the taVNS group performed worse for distractor than reversal cues. taVNS did not increase tonic pupil size and sAA. Only post hoc analyses indicated that the cortisol decline was steeper in the sham compared to the taVNS group. Exploratory analyses showed that taVNS decreased respiratory rate but did not affect CVA. The weak and unexpected effects found in this study might relate to the lack of parameters optimization for taVNS and invite to further investigate the effect of taVNS on cortisol and respiratory rate.

Effects of Green Color Exposure on Stress, Anxiety, and Pain during Peripheral Intravenous Cannulation in Dental Patients Requiring Sedation

Intravenous cannulation is an invasive procedure that causes stress, anxiety, and pain for many patients. A recent animal study found that exposure to green light induced antinociceptive and anxiolytic effects. This study examined whether green color exposure reduced stress, anxiety, and pain during peripheral intravenous cannulation (PIC) for sedation in dental patients. In this controlled clinical trial, 24 patients (mean age 40.9 years) were randomized to wear clear glasses or green-colored glasses for 15 min before PIC on two separate days in a cross-over manner. The primary outcome measures were salivary alpha-amylase (sAA) activity and stress-related hemodynamic changes, and the secondary outcome measures were the visual analog scale anxiety (VAS-A) and pain (VAS-P) scores during PIC. The sAA level in the clear group significantly increased during PIC compared with baseline, but did not increase in the green group. Median VAS-P scores during PIC were lower in the green group than in the clear group (VAS-P, 17.0 vs. 50.0). Green color exposure with glasses significantly reduced stress and pain during PIC without any adverse effects. This simple, safe, and effective method may be useful during painful medical procedures.

Salivary Markers of Stress in Grandparents Rearing Grandchildren in Rural Appalachia: The Role of Mental Health, Religiosity, and Social Support

This study examines changes in salivary cortisol and alpha-amylase among grandparents rearing grandchildren in rural Appalachia. Grandparent-caregivers experience greater stress than non-grandparent-caregivers. Participants included 20 grandparent-caregivers and a child for which they cared, who completed questionnaires assessing family functioning and mental health via interview. Grandparent-caregivers provided morning saliva samples once a year for two years. For grandparent-caregivers low in social support and religiosity, grandparent-caregiver depressive symptoms, child depressive symptoms, and child stress were associated with increased grandparent-caregiver salivary alpha-amylase. For grandparent-caregivers high in social support and religiosity, child depressive symptoms, child stress, and child aggression were associated with increased grandparent-caregiver cortisol.

Use of a non-invasive biomarker salivary alpha-amylase to assess the role of probiotics in sleep regulation and stress attenuation in surgical patients: A randomised double-blind clinical trial

BACKGROUND AND AIMS

The influence of gut microbiota on human behaviour, stress and sleep is currently a novel topic of research. A prospective double-blind randomised trial was planned to find out whether probiotics by alteration of the gut microbiome can allay surgery-related stress and improve sleep.

METHODS

A total of 160 elective surgical patients were randomised to receive either probiotic or placebo capsule twice daily for four and a half consecutive preoperative days. They were subjected to the Perceived Stress Scale (PSS) questionnaire, a psychomotor vigilance task (PVT) and estimation of salivary alpha-amylase (SAA), a well-known biomarker of stress on the evening of admission and on the evening just before the day of scheduled surgery. Data were analysed using Chi-square test, Student's t-test and Mann-Whitney test.

RESULTS

On comparing between the two groups, there was a significant difference in PSS scores, SAA levels and PVT scores after probiotic/placebo therapy. There was a decrease in the PSS scores by 11.38% (P < 0.05) and SAA levels by 11.38% (P < 0.05) and an increase in the PVT scores (12.13%, P < 0.05) following probiotic treatment.There was a mean difference of 52.85 in SAA levels in probiotic group and - 69.32 in placebo group with a definite fall in SAA levels in probiotic group, which showed that these patients had reduced stress levels and improved psychomotor vigilance implying improved sleep.

CONCLUSION

Gut microbiome alteration with probiotics results in lowering of psychological stress and sleep improvement in the preoperative period in surgical patients.

Physiological and Perceptual Recovery-Stress Responses to an Elite Netball Tournament

PURPOSE

To investigate and explore the relationships between physiological and perceptual recovery and stress responses to elite netball tournament workloads.

METHODS

Nine elite female netballers were observed across a 3-day (T1-3), 4-match tournament. Participants provided salivary samples for cortisol and alpha-amylase analysis, completed the Short Recovery Stress Scale (SRSS), and reported session ratings of perceived exertion. Inertial measurement units and heart-rate monitors determined player load, changes of direction (COD), summated heart-rate zones, and jumps.

RESULTS

Analysis revealed 6 significant SRSS time effects: (1) decreased recovery markers of physical performance (P = .042), emotional balance (P = .034), and overall recovery (P = .001) and (2) increased perceptual stress markers of muscular stress (P = .001), negative emotional state (P = .026), and overall stress (P = .010). Salivary cortisol decreased over the tournament (T1-3) before progressively increasing posttournament with greater salivary samples for cortisol on T+2 compared with T3 (P = .014, ES = -1.29; -2.24 to -0.22]) and T+1 (P = .031, ES = -1.54; -2.51 to -0.42). SRSS overall recovery moderately negatively correlated with COD (r = -.41, P = .028) and session ratings of perceived exertion (r = -.40, P = .034). Cumulative workload did not relate to posttournament perceptual or salivary responses. Percentage change in salivary variables related (P < .05) to total player load, total COD, and overall recovery across specific cumulative time periods.

CONCLUSIONS

During and after an elite netball tournament, athletes indicated increased perceptual stress and lack of recovery. The SRSS is a valuable tool for recovery-stress monitoring in elite tournament netball. It is recommended that practitioners monitor COD due to its negative influence on perceived overall recovery.

Changes Occurring on the Activity of Salivary Alpha-Amylase Proteoforms in Two Naturalistic Situations Using a Spectrophotometric Assay

Simple Summary

Salivary alpha-amylase (sAA) is considered a biomarker of acute stress since this enzyme is released in saliva after autonomic nervous system activation, in response to psychological or physical stress situations. This enzyme has different isoforms that could be differentially expressed depending on the stressful situation. The aims of the present research were (1) to develop and validate an easy and fast method to estimate the activity of the major sAA proteoforms (both non-glycosylated and glycosylated proteoforms) in saliva samples, and (2) to evaluate the possible changes occurring in the activity of both proteoforms when measured by this method in two different stress models (physical effort and psychological challenge). This new method was precise and, when applied to the different stress models, allowed to detect changes of different magnitudes in both proteoforms. Therefore, this research opens a new field for the evaluation of isoforms of sAA as potential biomarkers of stress.

Abstract

This study aimed to evaluate the changes in the activity of total salivary alpha-amylase (TsAA) and both the non-glycosylated and glycosylated salivary alpha-amylase proteoforms (NGsAA and GsAA, respectively) in physical and psychological stress models, estimated using a simple and easily set-up method. The method used was a spectrophotometric assay with 2-chloro-4-nitrophenyl-α-D-maltotriose (CNPG3) as a substrate, incubated with Concanavalin A (ConA) to remove most of the glycosylated protein from the sample. This method allowed the measurement of TsAA and estimation of NGsAA and GsAA activities with imprecision lower than 10%. When this method was applied to two different stress models, differences in the responses of the proteoforms were observed, with the NGsAA activity showing changes of higher magnitude after stress induction than the GsAA activity, and the highest correlation with the State–Trait Anxiety Inventory Scale in the Trier Social Stress Test (TSST). In conclusion, the activity of the two main sAA proteoforms can be easily estimated in saliva, and their measurement can provide additional information on TsAA activity in physical or psychological stress situations.

Frontal Electroencephalogram Alpha Asymmetry during Mental Stress Related to Workplace Noise

This study aims to investigate the effects of workplace noise on neural activity and alpha asymmetries of the prefrontal cortex (PFC) during mental stress conditions. Workplace noise exposure is a pervasive environmental pollutant and is negatively linked to cognitive effects and selective attention. Generally, the stress theory is assumed to underlie the impact of noise on health. Evidence for the impacts of workplace noise on mental stress is lacking. Fifteen healthy volunteer subjects performed the Montreal imaging stress task in quiet and noisy workplaces while their brain activity was recorded using electroencephalography. The salivary alpha-amylase (sAA) was measured before and immediately after each tested workplace to evaluate the stress level. The results showed a decrease in alpha rhythms, or an increase in cortical activity, of the PFC for all participants at the noisy workplace. Further analysis of alpha asymmetry revealed a greater significant relative right frontal activation of the noisy workplace group at electrode pairs F4-F3 but not F8-F7. Furthermore, a significant increase in sAA activity was observed in all participants at the noisy workplace, demonstrating the presence of stress. The findings provide critical information on the effects of workplace noise-related stress that might be neglected during mental stress evaluations.

Acute and Chronic Stress in Daily Police Service: A Three-Week N-of-1 Study

On duty, police officers are exposed to a variety of acute, threatening stress situations and organizational demands. In line with the allostatic load model, the resulting acute and chronic stress might have tremendous consequences for police officers' work performance and psychological and physical health. To date, limited research has been conducted into the underlying biological, dynamic mechanisms of stress in police service. Therefore, this ecological momentary assessment study examined the associations of stress, mood and biological stress markers of a 28-year-old male police officer in a N-of-1 study over three weeks (90 data points). Four times a day (directly after waking up, 30 minutes later, 6 hours later, before going to bed), he answered questions about the perceived stress and mood using a smartphone application. With each data entry, he collected saliva samples for the later assessment of salivary cortisol (sCort) and alpha-amylase (sAA). In addition, data was collected after six police incidents during duty. sCort and sAA were not related to perceived stress in daily life and did not increase in police incidents. Regarding mood measures, deterioration of calmness, but not valence and energy was associated with perceived stress. The results suggest continued police service to constitute a major chronic stressor resulting in an inability to mount a proper response to further acute stress. As an indicator of allostatic load, psychological and biological hyporesponsivity in moments of stress may have negative consequences for police officers' health and behavior in critical situations that require optimal performance. Prospectively, this research design may also become relevant when evaluating the efficacy of individualized stress management interventions in police training.

Positive and Negative Post Performance-Related Thoughts Predict Daily Cortisol Output in University Music Students

Psychophysiological research on music performance has focused on musicians' short-term affective, cognitive, and physiological responses. Much less attention has been devoted to the investigation of musicians' psychophysiological activity beyond the performance situation. Musicians report having both positive and negative performance-related thoughts (e.g., "My concert was good" and "I made a lot of mistakes") for days following performances. The potential physiological implications of this post-performance cognitive processing are largely unknown. Salivary cortisol (sC) and salivary alpha-amylase (sAA) are markers of the activity of the hypothalamic-pituitary-adrenal (HPA) axis and the sympathoadrenal medullary (SAM) system, respectively. The goal of the present study was to investigate whether self-reported positive and negative post performance-related thoughts predict the daily sC output and the daily sAA activity at the between- and within-person levels during a 2-day period following a solo music performance. Seventy-two university music students collected saliva samples six times per day and reported their positive and negative performance-related thoughts for 2 days after a solo performance. We tested between-person and within-person components of positive and negative post performance-related thoughts as predictors of the diurnal area under the curve with respect to ground (AUCg) for sC and sAA while adjusting for relevant person-level and day-level variables. Negative post performance-related thoughts were positively associated with sC AUCg both at the between- and within-person levels, whereas positive post performance-related thoughts were negatively associated with sC AUCg at the between-person level. Post performance-related thoughts did not significantly predict sAA AUCg. These findings provide evidence for a relationship between affectively valenced cognitive processing of a recent music performance and the activity of the HPA axis. Although the directionality of this relationship remains to be established more conclusively, the study makes a significant contribution to the literature on the prolonged psychophysiological effects of music performance situations and more broadly of social-evaluative stressors. Integrating the topic of post-performance cognitive processing and its optimal management into performance training programs would likely have positive effects on music students.

Salivary Alpha-Amylase in Experimentally-Induced Muscle Pain

Salivary alpha-amylase (sAA) is a marker of psychological stress and might also be a potential marker for pain-associated stress due its non-invasive, cost-effective, and stress-free collection. The current study aimed to investigate whether the levels of sAA are influenced by experimentally induced muscle pain. In this study, 26 healthy, pain-free and age-matched participants (23.8 ± 2.6 years) were included, 13 women and 13 men. Prior to the experiment, questionnaires assessing health and anxiety were completed. Muscle pain was then induced through intramuscular injection of 0.4 mL hypertonic saline (56.5 mg/mL) into the masseter muscle and unstimulated whole saliva samples were collected at baseline before injection, 2 min, and 15 min after injection. A commercially available colorimetric assay was used to analyze the sAA. Perceived pain and stress were assessed using a 0–100 Numeric Rating Scale for each sample. There were no significant differences in sAA levels prior and after injection of hypertonic saline (p > 0.05) although sAA levels showed a slight decrease during experimentally-induced muscle pain. However, a strong correlation was observed between self-reported pain and perceived level of stress during experimentally-induced muscle pain (r₂ = 0.744; p < 0.0001). Furthermore, there was a moderate correlation between the levels of sAA at baseline and during experimental pain (r₂ = 0.687; p < 0.0001). In conclusion, this study could not show any association between the levels of sAA and perceived pain and or/stress. However, since a significant strong correlation could be observed between perceived stress and pain intensity, this study indicates that experimentally-induced muscle pain could be used as a stress model.

Transcutaneous Vagus Nerve Stimulation (tVNS) Improves High-Confidence Recognition Memory but Not Emotional Word Processing

Previous clinical research found that invasive vagus nerve stimulation (VNS) enhanced word recognition memory in epileptic patients, an effect assumed to be related to the activation of brainstem arousal systems. In this study, we applied non-invasive transcutaneous auricular VNS (tVNS) to replicate and extend the previous work. Using a single-blind, randomized, between-subject design, 60 healthy volunteers received active or sham stimulation during a lexical decision task, in which emotional and neutral stimuli were classified as words or non-words. In a subsequent recognition memory task (1 day after stimulation), participants' memory performance on these words and their subjective memory confidence were tested. Salivary alpha-amylase (sAA) levels, a putative indirect measure of central noradrenergic activation, were also measured before and after stimulation. During encoding, pleasant words were more accurately detected than neutral and unpleasant words. However, no tVNS effects were observed on task performance or on overall sAA level changes. tVNS also did not modulate overall recognition memory, which was particularly enhanced for pleasant emotional words. However, when hit rates were split based on confidence ratings reflecting familiarity- and recollection-based memory, higher recollection-based memory performance (irrespective of emotional category) was observed during active stimulation than during sham stimulation. To summarize, we replicated prior findings of enhanced processing and memory for emotional (pleasant) words. Whereas tVNS showed no effects on word processing, subtle effects on recollection-based memory performance emerged, which may indicate that tVNS facilitates hippocampus-mediated consolidation processes.

Salivary α-Amylase Activity and Starch-Related Sweet Taste Perception in Humans

Starch-related sweet taste perception plays an important role as a part of the dietary nutrient sensing mechanisms in the oral cavity. However, the release of sugars from starchy foods eliciting sweetness has been less studied in humans than in laboratory rodents. Thus, 28 respondents were recruited and evaluated for their starch-related sweet taste perception, salivary alpha-amylase (sAA) activity, oral release of reducing sugars, and salivary leptin. The results demonstrated that a 2-min oral mastication of starchy chewing gum produced an oral concentration of maltose above the sweet taste threshold and revealed that the total amount of maltose equivalent reducing sugars produced was positively correlated with the sAA activity. In addition, respondents who consistently identified the starch-related sweet taste in two sessions (test and retest) generated a higher maltose equivalent reducing sugar concentration compared to respondents who could not detect starch-related sweet taste at all (51.52 ± 2.85 and 29.96 ± 15.58 mM, respectively). In our study, salivary leptin levels were not correlated with starch-related sweet taste perception. The data contribute to the overall understanding of oral nutrient sensing and potentially to the control of food intake in humans. The results provide insight on how starchy foods without added glucose can elicit variable sweet taste perception in humans after mastication as a result of the maltose generated. The data contribute to the overall understanding of oral sensing of simple and complex carbohydrates in humans.

Moving beyond belief: A narrative review of potential biomarkers for transcutaneous vagus nerve stimulation

Transcutaneous vagus nerve stimulation (tVNS) is a non-invasive neurostimulation technique that is currently being tested as a potential treatment for a myriad of neurological and psychiatric disorders. However, the working mechanisms underlying tVNS are poorly understood and it remains unclear whether stimulation activates the vagus nerve for every participant. Finding a biological marker of tVNS is imperative, as it can help guide research on clinical applications and can inform researchers on optimal stimulation sites and parameters to further optimize treatment efficacy. In this narrative review, we discuss five potential biomarkers for tVNS and review currently available evidence for these markers for both invasive and tVNS. While some of these biomarkers hold promise from a theoretical perspective, none of the potential biomarkers provide clear and definitive indications that tVNS increases the vagal activity or augments activity in the locus coeruleus-noradrenaline network. We conclude the review by providing several recommendations for how to tackle the challenges and opportunities when researching potential biomarkers for the effects of tVNS.

Assessing the association of university stress and physiological reactivity with decision-making among students

Compared with age-matched employees, university students report higher levels of chronic stress and this may affect their decision-making. The impact of chronic stress and physiological reactivity upon cognitive function is receiving more attention, but few studies have empirically assessed the associations of these variables concurrently. Our aim was to investigate if chronic student stress, as assessed by effort-reward imbalance (ERI) and overcommitment, and physiological reactivity, were related to decision-making. As measures of physiological reactivity, we collected salivary alpha-amylase (sAA) and continuously recorded heart rate variability (HRV) data from male students (n = 79) at pretest and immediately after some computerized decision-making tasks (simple and choice- reaction times). Our findings suggest that students who are higher in overcommitment and who are more physiologically reactive (sAA and HRV indices) at the pretest stage may be more "at-risk" of poor decision-making than others. If others can replicate our findings in more diverse samples, this will contribute to an evidence base for interventions targeted at reducing overcommitment, ERI, and dysregulated autonomic reactivity to improve decision-making.

Ambulatory Assessment of Psychological and Physiological Stress on Workdays and Free Days Among Teachers. A Preliminary Study

Objective

Teachers are affected by high levels of job stress, leading to one of the highest rates of burnout. The purpose of our pilot study was to investigate the diurnal course of teachers’ psychological and physiological stress responses [cortisol levels, alpha-amylase, heart rate (HR), and heart rate variability (HRV)]. Another aim of the project was to test the applicability of ambulatory assessment methods in daily teaching situations.

Methods

In a non-clinical sample of eight primary school teachers (mean age = 43, SD = 15.22, 6 females) in Switzerland, continuous biopsychological data on two workdays and a free day were assessed. The teachers’ HRs and HRV were measured continuously using an ambulatory ECG. Additionally, eight saliva samples were collected from the teachers repeatedly throughout the day to determine the diurnal course of salivary cortisol and alpha-amylase (sAA). Perceived stress and anger ratings were assessed simultaneously.

Results

As hypothesized, the teachers’ morning cortisol levels, perceived stress, and anger levels were significantly higher, and their overall HRV was significantly lower on workdays than on a free day. Conversely, sAA levels and HRs showed no significant differences between working and free days. Salivary markers exhibited the expected diurnal course, with decreasing cortisol and increasing sAA levels over the course of the day, while self-rated stress reached the maximum at midday during working days.

Conclusion

The results of the present explorative study show that physiological and psychological parameters differ within working and free days for teachers. A comparison between working and free days resulted in differences in morning cortisol levels, HRV as well as stress and anger levels. The ambulatory assessment method was found to be applicable in daily teaching situations.

Pilot Study on the Effect of Biophysical Therapy on Salivary Alpha-Amylase as a Surrogate Measure of Anxiety/Stress: In Search of a Novel Noninvasive Molecular Approach for the Management of Stress

Anxiety and depression impact dramatically on public health, underlying the importance of alternative cost-effective treatments. Previous studies have shown that biophysical treatment can significantly reduce anxiety symptoms and recently, salivary alpha-amylase (SAA) has been identified as an objective correlate of the sympathetic-parasympathetic imbalance related to increased stress burden, defined as allostatic load. The aim of this study was to evaluate the effect of biophysical therapy on SAA levels, in addition to the Depression Anxiety Stress Scale (DASS)-21 questionnaire. Twenty-four workers (sales representatives) presenting with mild anxiety/stress symptoms (Generalized Anxiety Disorder 7-item scale of > 5) were randomized to biophysical treatment (N = 12) or placebo control (N = 12). The biophysical group underwent electromagnetic information transfer through an aqueous system procedure, with daily self-administration for one month. SAA collection and the DASS-21 questionnaire were undertaken at baseline and after one month in all patients. Clinical characteristics and baseline DASS-21 subscale scores were similar between placebo and biophysical group at baseline. After one month, patients receiving biophysical therapy had significantly reduced SAA levels compared to the placebo group (27.8 ± 39.4 vs. 116.8 ± 114.9 U/mL, p = 0.019). All three DASS-21 subscales, depression (9.3 ± 5.1 vs. 5.7 ± 5.5, p = 0.1), anxiety (6.7 ± 25 vs. 3.7 ± 2.2, p = 0.0049) and stress (10.8 ± 4.2 vs. 7.3 ± 3.7, p = 0.041) were also decreased after biophysical treatment compared to placebo after one month. Our findings suggest that biophysical therapy can benefit workers with mild (subclinical) anxiety/stress. These results were also validated by the concomitant reduction of SAA levels and an improvement in DASS-21 subscales. The underlying molecular mechanisms of this therapy remain to be characterized.

Salivary Alpha-Amylase Mediates the Increase in Hunger Levels in Adolescents with Excess Weight after Viewing Food Images

Background: Salivary alpha-amylase (sAA) initiates the digestion process in the mouth and its levels might influence feelings of hunger and the propensity toward obesity. This study aims to evaluate basal differences in sAA between adolescents with excess weight (EW) and normal weight (NW), and the associations between sAA levels and feelings of hunger after viewing food images. Methods: Adolescents (13-18 years old) classified as EW (n = 30) or NW (n = 30) participated in the study. Saliva samples were collected before the administration of a food-choice task. Hunger was evaluated before and after the food-choice task. Results: EW adolescents showed lower basal sAA levels than NW adolescents and a greater increase in hunger levels after viewing food images. In addition, sAA levels had a significant inverse relationship with the increase in hunger in EW adolescents, but not in NW adolescents. Finally, significant inverse associations between sAA, BMI, and body fat percentage were found. Conclusions: Levels of hunger and changes therein, after viewing food are dependent on sAA levels in EW adolescents. This finding indicates that sAA levels may be a mediator of feelings of hunger in individuals with overweight in the context of viewing food cues, suggesting the utility of the sAA enzyme as a marker of hunger and propensity toward obesity.

Association of salivary alpha-amylase and salivary flow rate with working memory functioning in healthy children

The aim of this study was to examine the association between auditory and visual working memory (WM) performance and salivary alpha-amylase (sAA) and salivary flow rate (SFR) in a sample of 63 children (38 boys). WM was assessed by means of WISC-V subtests: four auditory subtests (Digit Span and Letter-Number Sequencing) and one visual subtest (Picture Span). SAA activity, output, and SFR were measured at baseline (10 min prior to testing), one minute prior to testing, one minute after the end of the auditory WM subtests and one minute after the end of the visual WM subtest. Our statistical analyses showed an association among SAA activity, output and SFR levels and the number of recalled digits in the last attempt score in Letter-Number Sequencing subtest. Specifically, our results showed that working performance in this task was associated with a concurrent decrease in SFR (r(63) = -0.423, p < .05). This salivary measure was the best predictor of this specific index of working memory performance (β = -0.423, p < .05). These results show that the changes in SFR, which represents changes in parasympathetic tone, could be employed in future studies as a noninvasive marker of working memory performance in child studies.

Listening to Sutra-Chanting Reduces Bereavement Stress in Japan

Buddhist Chaplains chanting sutras after the Great East Japan Earthquake in 2011 often encountered survivors who felt that hearing sutra chanting itself ameliorated their bereavement grief. This research is the first experimental examination of the effects of sutra chanting on listeners' bereavement stress. Prior research demonstrates that sudden pet loss causes bereavement stress in students and that physiological stress can be noninvasively measured by salivary alpha-amylase. We asked Japanese college students to raise pet goldfish until they developed an attachment to them, then confiscated the fish, and told the students that they had to be killed. To compare the bereavement stress of groups listening and not listening to sutra chanting, we used psychological and salivary analyses. Perceived Stress Scale (PSS), Multidimensional Empathy Scale (MES), and State half of the State Trait Anxiety Inventory (STAI) psychological scales showed no statistically significant differences between sutra and control groups, but salivary analyses indicated measurable stress reduction in the sutra-listening group only. This pilot study tentatively confirmed the hypothesis that listening to Buddhist sutra chanting reduces Japanese bereavement stress. Further research is needed both to verify these stress-reduction effects and to determine whether such effects are primarily musical or cultural/spiritual.

The creative thinking cognitive process influenced by acute stress in humans: an electroencephalography study

This study examined the underlying neural mechanism of acute stress affecting creative thinking. Twenty-six male participants underwent the Alternative Uses Test before and after acute stress test (Montreal Imaging Stress Task). Compared to before stress, stressed participants responded with higher salivary cortisol and salivary alpha-amylase. The electroencephalogram results indicated a general decrease in upper-frequency alpha power after stress, compared with that of before stress. The decrease in upper-frequency alpha power observed in the first stage after exposure to stress was related to memory and attention. Additionally, stress also reduced the differences between individuals with different creative abilities. In summary, these findings indicated that acute stress impaired creative thinking and primarily affected the earlier phase of the process of creative cognition. This study provides some practical implications for educational practice and corporate innovation in that a more relaxed environment promotes creative output. Lay Summary Acute stress impaired creative thinking performance and mainly affects the earlier phase of the process of creative cognition. Additionally, stress seems to reduce the differences between individuals with different creative abilities.

Salivary alpha-amylase activity and concentration in horses with acute abdominal disease: Association with outcome

BACKGROUND

Salivary biomarkers could be useful to objectively evaluate critical illness and prognosis for survival in horses with acute abdominal disease.

OBJECTIVES

To compare salivary alpha-amylase (sAA) activity and concentration in healthy horses and horses with acute abdominal disease, and evaluate the association between sAA activity and concentration with disease severity and outcome.

STUDY DESIGN

A prospective cohort.

METHODS

sAA activity, measured using a colorimetric commercial kit, and concentration, measured using a Time-resolved immunofluorometric assay, in 25 healthy horses and in 33 horses with acute abdominal disease was compared using an ANOVA. Associations between survival to discharge and sAA activity and concentration and other clinical parameters were examined using univariable logistic regression and Spearman correlation.

RESULTS

sAA activity and concentration were different between healthy (median = 4.3 [2.6-11.2] IU/L and 58.4 [53.4-80.6] ng/mL, respectively) and diseased (median = 29.8 [14.2-168.9] IU/L and 388.3 [189.1-675.8] ng/mL, respectively) (P<0.001). The sAA activity was higher in non-survivors (median = 479.0 [78.7-2064.0] IU/L, n = 8) compared to survivors (median = 19.3 [12.1-103.7] IU/L, n = 25, P<0.001) and sAA activity and concentration correlated (P<0.001) moderately with HR (r = 0.66 and r = 0.61, respectively). sAA activity correlated weakly with salivary cortisol (r = 0.45, P<0.001) and systemic inflammatory response syndrome score (r = 0.43, P<0.05), while activity and concentration correlated (P<0.001) moderately with plasma lactate concentration (r = 0.57 and r = 0.60, respectively). The sAA activity was significantly (P = 0.01) associated with increased risk of nonsurvival.

MAIN LIMITATIONS

Pain scores were not recorded. The sample population was small.

CONCLUSIONS

The sAA activity, but not concentration, shows potential as a biomarker of prognosis for survival in horses with acute abdominal disease. The summary is available in Spanish - see Supporting Information.

Associations between digit ratio (2D4D), mood, and autonomic stress response in healthy men

The ratio between the length of the second (index) and the fourth (ring) finger (2D4D) is a putative biomarker of prenatal testosterone (T) exposure, with higher exposure leading to a smaller ratio. 2D4D has further been linked to mental and somatic disorders. Healthy male Swiss recruits (N = 245; M_age = 20.30 years) underwent a psychosocial stress test. Mood and salivary alpha-amylase (sAA) were assessed before and after the stress test, while heart rate (HR) and heart rate variability (HRV) were measured continuously. Additionally, 2D4D (right: R2D4D; left: L2D4D) was determined and divided into quartile groups. Correlation analysis showed no associations between R/L2D4D and outcome measures. Comparing calculated quartiles for R2D4D, subjects in the lowest R2D4D quartile expressed trendwise (p < 0.10) lower positive and higher negative affect, significantly elevated sAA activity (p < 0.05), but no HR and HRV differences at baseline as compared to subjects in the upper three quartiles. With regard to acute stress, subjects in the lowest as compared to subjects in the upper three R2D4D quartiles showed a higher increase of negative affect and a stronger cardiac response (p < 0.05), but no alterations in positive affect and sAA activity. Young healthy men in the lowest R2D4D quartile revealed a more negative affect and increased physiological activity at baseline and in response to acute stress. An exposure to high levels of prenatal T might constitute a risk factor potentially increasing vulnerability to stress-related disorders in men.

Basal Levels of Salivary Alpha-Amylase Are Associated with Preference for Foods High in Sugar and Anthropometric Markers of Cardiovascular Risk

Salivary alpha-amylase (sAA) influences the perception of taste and texture, features both relevant in acquiring food liking and, with time, food preference. However, no studies have yet investigated the relationship between basal activity levels of sAA and food preference. We collected saliva from 57 volunteers (63% women) who we assessed in terms of their preference for different food items. These items were grouped into four categories according to their nutritional properties: high in starch, high in sugar, high glycaemic index, and high glycaemic load. Anthropometric markers of cardiovascular risk were also calculated. Our findings suggest that sAA influences food preference and body composition in women. Regression analysis showed that basal sAA activity is inversely associated with subjective but not self-reported behavioural preference for foods high in sugar. Additionally, sAA and subjective preference are associated with anthropometric markers of cardiovascular risk. We believe that this pilot study points to this enzyme as an interesting candidate to consider among the physiological factors that modulate eating behaviour.

Effect of Seminar on Compassion on student self-compassion, mindfulness and well-being: A randomized controlled trial

OBJECTIVE

Mindfulness-based interventions have been shown to have psychological benefits in college students. We explored the effects of an academic Seminar on Compassion on student psychological health.

PARTICIPANTS

Forty-one participants (14 male, 27 female, mean age 19.8 ± 1.4 years) were assessed pre- and post- spring semesters 2013 and 2014.

METHODS

Students were randomized to the Seminar on Compassion or a wait-list control group. Participants completed self-report measures on anxiety, depression, perceived stress, self-compassion, compassion and mindfulness. Salivary alpha-amylase was also assessed.

RESULTS

At baseline, self-compassion and mindfulness were negatively correlated with depression, anxiety, and perceived stress. There were significant changes between the intervention and control group from Time 1 to Time 2 in mindfulness, self-compassion, compassion, and salivary alpha-amylase; however, there were no significant changes in depression, anxiety, and perceived stress.

CONCLUSIONS

The course was effective in increasing mindfulness, self-compassion and compassion, and decreasing a salivary marker of stress.

Effects of Transcutaneous Vagus Nerve Stimulation (tVNS) on the P300 and Alpha-Amylase Level: A Pilot Study

Recent research suggests that the P3b may be closely related to the activation of the locus coeruleus-norepinephrine (LC-NE) system. To further study the potential association, we applied a novel technique, the non-invasive transcutaneous vagus nerve stimulation (tVNS), which is speculated to increase noradrenaline levels. Using a within-subject cross-over design, 20 healthy participants received continuous tVNS and sham stimulation on two consecutive days (stimulation counterbalanced across participants) while performing a visual oddball task. During stimulation, oval non-targets (standard), normal-head (easy) and rotated-head (difficult) targets, as well as novel stimuli (scenes) were presented. As an indirect marker of noradrenergic activation we also collected salivary alpha-amylase (sAA) before and after stimulation. Results showed larger P3b amplitudes for target, relative to standard stimuli, irrespective of stimulation condition. Exploratory post hoc analyses, however, revealed that, in comparison to standard stimuli, easy (but not difficult) targets produced larger P3b (but not P3a) amplitudes during active tVNS, compared to sham stimulation. For sAA levels, although main analyses did not show differential effects of stimulation, direct testing revealed that tVNS (but not sham stimulation) increased sAA levels after stimulation. Additionally, larger differences between tVNS and sham stimulation in P3b magnitudes for easy targets were associated with larger increase in sAA levels after tVNS, but not after sham stimulation. Despite preliminary evidence for a modulatory influence of tVNS on the P3b, which may be partly mediated by activation of the noradrenergic system, additional research in this field is clearly warranted. Future studies need to clarify whether tVNS also facilitates other processes, such as learning and memory, and whether tVNS can be used as therapeutic tool.

Animal Assisted Therapy (AAT) Program As a Useful Adjunct to Conventional Psychosocial Rehabilitation for Patients with Schizophrenia: Results of a Small-scale Randomized Controlled Trial

Currently, one of the main objectives of human-animal interaction research is to demonstrate the benefits of animal assisted therapy (AAT) for specific profiles of patients or participants. The aim of this study is to assess the effect of an AAT program as an adjunct to a conventional 6-month psychosocial rehabilitation program for people with schizophrenia. Our hypothesis is that the inclusion of AAT into psychosocial rehabilitation would contribute positively to the impact of the overall program on symptomology and quality of life, and that AAT would be a positive experience for patients. To test these hypotheses, we compared pre-program with post-program scores for the Positive and Negative Syndrome Scale (PANSS) and the EuroQoL-5 dimensions questionnaire (EuroQol-5D), pre-session with post-session salivary cortisol and alpha-amylase for the last four AAT sessions, and adherence rates between different elements of the program. We conducted a randomized, controlled study in a psychiatric care center in Spain. Twenty-two institutionalized patients with chronic schizophrenia completed the 6-month rehabilitation program, which included individual psychotherapy, group therapy, a functional program (intended to improve daily functioning), a community program (intended to facilitate community reintegration) and a family program. Each member of the control group (n = 8) participated in one activity from a range of therapeutic activities that were part of the functional program. In place of this functional program activity, the AAT-treatment group (n = 14) participated in twice-weekly 1-h sessions of AAT. All participants received the same weekly total number of hours of rehabilitation. At the end of the program, both groups (control and AAT-treatment) showed significant improvements in positive and overall symptomatology, as measured with PANSS, but only the AAT-treatment group showed a significant improvement in negative symptomatology. Adherence to the AAT-treatment was significantly higher than overall adherence to the control group's functional rehabilitation activities. Cortisol level was significantly reduced after participating in an AAT session, which could indicate that interaction with the therapy dogs reduced stress. In conclusion, the results of this small-scale RCT suggest that AAT could be considered a useful adjunct to conventional psychosocial rehabilitation for people with schizophrenia.

Influence of a Suggestive Placebo Intervention on Psychobiological Responses to Social Stress: A Randomized Controlled Trial

We tested the hypothesis that a suggestive placebo intervention can reduce the subjective and neurobiological stress response to psychosocial stress. Fifty-four healthy male subjects with elevated levels of trait anxiety were randomly assigned in a 4:4:1 fashion to receive either no treatment (n = 24), a placebo pill (n = 24), or a herbal drug (n = 6) before undergoing a stress test. We repeatedly measured psychological variables as well as salivary cortisol, alpha-amylase, and heart rate variability prior to and following the stress test. The stressor increased subjective stress and anxiety, salivary cortisol, and alpha-amylase, and decreased heart rate variability (all P < .001). However, no significant differences between subjects receiving placebo or no treatment were found. Subjects receiving placebo showed increased wakefulness during the stress test compared with no-treatment controls (P < .001). Thus, the suggestive placebo intervention increased alertness, but modulated neither subjective stress and anxiety nor the physiological response to psychosocial stress.

Salivary cytokines as a minimally-invasive measure of immune functioning in young children: correlates of individual differences and sensitivity to laboratory stress

There is growing interest in minimally-invasive measures of environmentally-responsive biological systems in developmental science. Contributing to that endeavor, this study explores the intercorrelations, correlates, and task-sensitivity of proinflammatory salivary cytokines in childhood. Saliva was sampled from 125 healthy five-year old children (49% male) across a series of cognitive and emotional challenge laboratory tasks. Samples were assayed for cytokines (IL-1β, IL-6, IL-8, TNFα), and markers of hypothalamic-pituitary-adrenal (HPA) and autonomic nervous system (ANS) activation (salivary cortisol and alpha-amylase [sAA]). Cytokines were positively intercorrelated and task-sensitivity varied. Except IL-8, cytokines were elevated in children with oral health issues and tobacco smoke exposure. Among boys, cytokines were positively related to sAA and negatively related to cortisol. The findings suggest that in healthy children, salivary cytokine levels reflect compartmentalized oral immune activity. Associations between ANS and HPA activity and cytokines in saliva may present opportunities for minimally-invasive methods to explore neuroendocrine-immune interactions during development.

Self-compassionate young adults show lower salivary alpha-amylase responses to repeated psychosocial stress

In this study we tested the hypothesis that participants higher in dispositional self-compassion would show lower stress-induced reactivity of salivary alpha-amylase (sAA), a marker of sympathetic nervous system activation. Thirty-three healthy participants (18-34 years old) were exposed to a standardized laboratory stressor on two consecutive days. Self-compassion, self-esteem, and demographic factors were assessed by questionnaire and sAA was assessed at baseline and at 1, 10, 30, and 60 minutes following each stressor. Self-compassion was a significant negative predictor of sAA responses on both days. This relationship remained significant when controlling for self-esteem, subjective distress, age, gender, ethnicity, and Body Mass Index (BMI). These results suggest that self-compassion may serve as a protective factor against stress-induced physiological changes that have implications for health.

Age Differences of Salivary Alpha-Amylase Levels of Basal and Acute Responses to Citric Acid Stimulation Between Chinese Children and Adults

It remains unclear how salivary alpha-amylase (sAA) levels respond to mechanical stimuli in different age groups. In addition, the role played by the sAA gene (AMY1) copy number and protein expression (glycosylated and non-glycosylated) in sAA activity has also been rarely reported. In this study, we analyzed saliva samples collected before and after citric acid stimulation from 47 child and 47 adult Chinese subjects. We observed that adults had higher sAA activity and sAA glycosylated levels (glycosylated sAA amount/total sAA amount) in basal and stimulated saliva when compared with children, while no differences were found in total or glycosylated sAA amount between them. Interestingly, adults showed attenuated sAA activity levels increase over those of children after stimulation. Correlation analysis showed that total sAA amount, glycosylated sAA amount, and AMY1 copy number × total sAA amount were all positively correlated with sAA activity before and after stimulation in both groups. Interestingly, correlation r between sAA levels (glycosylated sAA amount and total sAA amount) and sAA activity decreased after stimulation in children, while adults showed an increase in correlation r. In addition, the correlation r between AMY1 copy number × total sAA amount and sAA activity was higher than that between AMY1 copy number, total sAA amount, and sAA activity, respectively. Taken together, our results suggest that total sAA amount, glycosylated sAA amount, and the positive interaction between AMY1 copy number and total sAA amount are crucial in influencing sAA activity before and after stimulation in children and adults.

Enhanced stress response by a bilateral feet compared to a unilateral hand Cold Pressor Test

The Cold Pressor Test (CPT) is a frequently employed laboratory stress protocol. However, with many experimental designs the application in its classic form (immersion of the dominant hand into ice-water) is problematic as unilateral stimulation may need to be avoided and/or hands are required for further measurements. Here, we describe a simple modification of the classic CPT in which both feet are immersed into ice-water and compare the evoked neuroendocrine stress response to the classic CPT in a within-subjects design. Twenty-four healthy participants were exposed to each of both CPT versions on two subsequent days in randomized order. Heart rate, blood pressure, salivary alpha-amylase and cortisol were measured at baseline and during or after CPT exposition, respectively, along with subjective ratings of pain and stress. The bilateral feet CPT induced marked increases in all measured stress parameters. Moreover, with the exception of blood pressure, autonomic and endocrine responses were enhanced compared to the classic CPT. The bilateral feet CPT thus is a valid and simple modification and may be useful when the application of the classic CPT is unfeasible or a stronger neuroendocrine stress response is of interest.

Psychometric and biohormonal indices of dental anxiety in children. A prospective cohort study

The stress of dental treatment often elicits negative emotions in children, expressed as dental fear or anxiety. Highly anxious children obstruct treatment and avoid therapy, further amplifying oral health problems. The aim of this study was to examine the neuroendocrine and autonomic nervous system responses to dental treatment and their possible interactions and associations with psychometric indices of anxiety, caries, previous dental experience, anesthesia, age and gender in school children. Upon informed consent, saliva was obtained from 97 children (59% males, mean age ±  SD: 89.73 ± 15 months) in the Clinic of pediatric dentistry before treatment, immediately post-treatment and at the recall visit to determine cortisol and salivary alpha-amylase (sAA) levels. Dental and general anxiety was assessed through specific questionnaires completed by the children. Compared to pre-treatment, cortisol levels were increased following treatment, while sAA levels were higher at the recall. Pre- and post-treatment cortisol and sAA responses were positively correlated. Dental and general anxiety questionnaire scores were also significantly correlated with each other. The integrated autonomic and neuroendocrine responses prior to treatment were correlated with state anxiety and those following treatment with dental anxiety. However, univariable and multivariable linear regression analysis associated post-treatment cortisol, but not sAA, levels with dental anxiety. No associations of cortisol or sAA responses with caries, age, gender, previous dental experience or anesthesia were detected. These data provide some evidence that both sAA and cortisol levels are altered in children in anticipation or during dental treatment, but only cortisol levels are associated to dental anxiety.

Individual differences in the cortisol and salivary α-amylase awakening responses in early childhood: relations to age, sex, and sleep

Recent studies have examined post-waking changes in cortisol as a marker of HPA functioning, but questions remain about the stability of this response, as well as its relation to sleep and other ANS markers. The purposes of this study were to a) examine the presence and developmental changes in the cortisol awakening response (CAR) and salivary α-amylase awakening (sAA-AR) in a toddler sample and b) determine whether and how sleep relates to these responses in this age group. We measured cortisol and sAA upon awakening (and 30 min post-waking) and sleep characteristics using actigraphy (e.g., total sleep time, sleep efficiency, number of awakenings) in toddlers (N = 47; 36% female, ages 12-24 months). Forty-six percent of toddlers demonstrated a CAR and 52% demonstrated a sAA-AR. Strength of either response did not change linearly with age. Additionally, likelihood of demonstrating the CAR and sAA-AR was unrelated to age, sex, awakening time, time between samples, and time since feeding. Higher waking cortisol levels were associated with a shorter total sleep time and an earlier awakening. No associations were observed between sleep characteristics and the sAA-AR, ps > .05. Our findings suggest that these awakening responses function independently of sleep in toddlers. Additionally, the lack of change in percentage of children showing a CAR or sAA-AR across these ages suggests that these responses are stable and not emerging reliably across the second year of life.

Psychophysiological and stress responses to competition in team sport coaches: an exploratory study

Examinations of stress in coaches have mainly been qualitative and focused on chronic stressors. This exploratory study examined stress responses in coaches during competition, including psychological and physiological indices. Using reversal theory, we examined metamotivational state profiles during competition. Ten male team sport coaches (mean age 39.8 ± 13.12 years) reported levels of subjective stress, pleasant and unpleasant emotions, metamotivational state, and provided saliva samples, on a competition day: 15 min prior to the pre-match team talk; start of the match; end of the first half; start of the second half, and end of the match, then at equivalent times on a noncompetition day. Saliva samples were assayed for alpha-amylase activity. On competition day, alpha-amylase activity was significantly higher, as were subjective stress, arousal, and unpleasant emotions. Prior to and during active play, participants were mainly in the conformist, alloic (other-oriented), and mastery states, and at the end of the match, in the telic and sympathy states. Only 22 metamotivational state reversals were observed, mostly at the start and end of the match. The elevated levels of subjective stress, alpha-amylase activity, and unpleasant emotions suggest that educational programs may be useful for some coaches to manage psychological states during competition.

Asymmetry in children's salivary cortisol and alpha-amylase in the context of marital conflict: links to children's emotional security and adjustment

Recent research supports the promise of examining interactive models of physiological processes on children's adjustment. The present study investigates interactions between children's autonomic nervous system activity and adrenocortical functioning in the context of marital discord; specifically, testing models of concurrent responses proposed by Bauer et al. ([2002] Developmental and Behavioral Pediatrics 23:102-113) in the prediction of children's behavioral responses to conflict and adjustment. Asymmetry and symmetry in children's salivary alpha-amylase and cortisol were examined in 195 children (M age = 8 years) in response to viewing conflict vignettes. Results were partially consistent with an interactive model in the context of high marital discord; asymmetry among higher alpha-amylase and lower cortisol related to higher emotional insecurity and concurrent and subsequent maladjustment. In contrast, patterns of symmetrical responses were related to greater maladjustment for children exposed to lower levels of marital discord, supporting an additive model. Findings support the importance of a multisystem approach to investigating the adaptiveness of children's physiological stress responses, while also highlighting the value of considering physiological responses in the context of family risk.

Disentangling sources of individual differences in diurnal salivary α-amylase: reliability, stability and sensitivity to context

In the present study, we employ a longitudinal design and a generalizability framework to examine the sources of variance in the diurnal rhythm of salivary α-amylase (sAA). The sample consisted of 122 first-year law students (55% male, mean age=23.9 years), who collected five saliva samples on each of three consecutive days at each of five data collection waves. In total, over 6900 saliva samples were collected, which allowed us to examine the properties of diurnal variation in sAA in great detail. Systematic individual differences accounted for 15-29% of the variability in the awakening response and diurnal slope, and for 61-65% of the variation in overall daily levels (i.e., diurnal mean, area under the curve with respect to ground [AUCg]). Although less than 1% of the variation was due to differences between waves and between days, the generalizability analyses revealed that between 16% and 17% of the variance in the diurnal mean, slope and AUCg is due to person by wave interactions, indicating that individuals vary in their biological sensitivity to environmental influences. In sum, this study documents sufficient stability and variation in diurnal sAA to warrant future studies on the origins and consequences of alterations in the diurnal rhythm of sAA worthwhile, and proposes guidelines on obtaining reliable measures.

Salivary alpha-amylase activity and salivary flow rate in young adults

The secretion of salivary alpha-amylase (sAA) is more associated with psychoneuroendocrinological response to stress than with the flow rate and age. The aim of this cross sectional study is to build an explanatory model based on patterns of relationship between age 20-39 in resting and stimulated saliva under no stressful condition in healthy volunteers. Both resting and stimulated saliva were collected from 40 subjects. The sAA values were log-transformed, the normality assumption was verified with the Shapiro-Wilk test and the reliability of the measurements was estimated by the Pearsons’ r correlation coefficient. The estimated model was based on the theory of the Linear Mixed Models. Significant mean changes were observed in flow rate and sAA activity between resting and stimulated saliva. The final model consists of two components, the first revealed a positive correlation between age and sAA while the second one revealed a negative correlation between the interaction of age × flow rate in its condition (resting or stimulated saliva), with sAA. Both flow rate and age influence sAA activity.

Sociodemographic risk, parenting, and effortful control: relations to salivary alpha-amylase and cortisol in early childhood

Early sociodemographic risk, parenting, and temperament were examined as predictors of the activity of children's (N = 148; 81 boys, 67 girls) hypothalamic-pituitary-adrenal axis and autonomic nervous system. Demographic risk was assessed at 18 months (T1), intrusive/overcontrolling parenting and effortful control were assessed at 30 months (T2), and salivary cortisol and alpha-amylase were collected at 72 (T3) months of age. Demographic risk at T1 predicted lower levels of children's effortful control and higher levels of mothers' intrusive/overcontrolling parenting at T2. Intrusive/overcontrolling parenting at T2 predicted higher levels of children's cortisol and alpha-amylase at T3, but effortful control did not uniquely predict children's cortisol or alpha-amylase levels. Findings support the open nature of stress responsive physiological systems to influence by features of the early caregiving environment and underscore the utility of including measures of these systems in prevention trials designed to influence child outcomes by modifying parenting behavior.