α-Amylase as a reliable and convenient measure of sympathetic activity: don't start salivating just yet!

Oral health, organic and inorganic saliva composition of men with Schizophrenia: Case-control study

BACKGROUND

Schizophrenia (SCZ) presents complex challenges related to diagnosis and clinical monitoring. The study of conditions associated with SCZ can be facilitated by using potential markers and patterns that provide information to support the diagnosis and oral health.

METHODS

The salivary composition of patients diagnosed with SCZ (n = 50) was evaluated and compared to the control (n = 50). Saliva samples from male patients were collected and clinical parameters were evaluated. The concentration of total proteins and amylase were determined and salivary macro- and microelements were quantified by ICP OES and ICP-MS. Exploratory data analysis based on artificial intelligence tools was used in the investigation.

RESULTS

There was a significant increase in the salivary concentrations of Al, Fe, Li, Mg, Na, and V, higher prevalence of caries (p < 0.001), periodontal disease (p < 0.001), and reduced salivary flow rate (p = 0.019) in SCZ patients. Also, samples were grouped into six clusters. As, Co, Cr, Cu, Mn, Mo, Ni, Se, and Sr were correlated with each other, while Fe, K, Li, Ti, and V showed the highest concentrations in the samples distributed in the clusters with the highest association between SZC patients and controls.

CONCLUSIONS

The results obtained indicate changes in salivary flow, organic composition, and levels of macro- and microelements in SCZ patients. Salivary concentrations of Fe, Mg, and Na may be related to oral conditions, higher prevalence of caries, and periodontal disease. The exploratory analysis showed different patterns in the salivary composition of SCZ patients impacted by associations between oral health conditions and the use of medications. Future studies are encouraged to confirm the results investigated in this study.

Changes in salivary proteome before and after cigarette smoking in smokers compared to sham smoking in nonsmokers: A pilot study

INTRODUCTION

Smoking is the leading cause of preventable disease. Although smoking results in an acute effect of relaxation and positive mood through dopamine release, smoking is thought to increase stress symptoms such as heart rate and blood pressure from nicotine-induced effects on the HPA axis and increased cortisol. Despite the importance in understanding the mechanisms in smoking maintenance, little is known about the overall protein and physiological response to smoking. There may be multiple functions involved that if identified might help in improving methods for behavioral and pharmacological interventions. Therefore, our goal for this pilot study was to identify proteins in the saliva that change in response to an acute smoking event versus acute sham smoking event in smokers and non-smokers, respectively.

METHODS

We employed the iTRAQ technique followed by Mass Spectrometry to identify differentially expressed proteins in saliva of smokers and non-smokers after smoking cigarettes and sham smoking, respectively. We also validated some of the salivary proteins by ELISA or western blotting. In addition, salivary cortisol and salivary amylase (sAA) activity were measured.

RESULTS

In all, 484 salivary proteins were identified. Several proteins were elevated as well as decreased in smokers compared to non-smokers. Among these were proteins associated with stress response including fibrinogen alpha, cystatin A and sAA. Our investigation also highlights methodological considerations in study design, sampling and iTRAQ analysis.

CONCLUSIONS

We suggest further investigation of other differentially expressed proteins in this study including ACBP, A2ML1, APOA4, BPIB1, BPIA2, CAH1, CAH6, CYTA, DSG1, EST1, GRP78, GSTO1, sAA, SAP, STAT, TCO1, and TGM3 that might assist in improving methods for behavioral and pharmacological interventions for smokers.

Salivary Cortisol and α-Amylase Production at Awakening is Associated with Positivity (POS) Levels in Healthy Young Subjects

A large variety of positive outcomes including social adjustment, psychological well-being and health, have been recently closely associated with positivity (POS). On the assumption that differences in the POS degree might be associated with different individual neuroendocrine assets that enables people to cope effectively with stress, the present study examined the association between POS, salivary cortisol and α-Amylase (α-Amy) production in a group of healthy male volunteers university students, respectively scoring high (POS-H, N = 10) and low (POS-L, N = 10) in POS. Participants were selected from a larger sample of 300 students of the Medical School at Sapienza University of Rome on the basis of their positivity level: POS was analysed and the upper and lower 25% were invited to participate in this new study. The findings report a distinct salivary cortisol and α-Amy production in the study population: in comparison to the POS-H group, the POS-L subjects presented a lower salivary cortisol awake response (CAR) and a flattened α-Amy production at 30 and 60 min after awakening. In addition, salivary cortisol and α-Amy areas under the curve (AUCs), which were calculated as indicators of the two subclinical biomarkers production during the first hour after awakening, resulted significantly lower in the POS-L group in comparison to the POS-H group. Further studies on larger and different populations are needed to definitively confirm that the different cortisol and α-Amy secretion patterns between POS-H and POS-L individuals is associated with a potentially better capacity to preserving an adequate quality of life in individuals being equipped with a system apparently able to better respond to external and/or internal stimuli. Lastly, a better understanding of the biological correlates of POS is crucial to design psychological interventions able to take advantage of individuals’ assets and thus to integrate and strengthen the efficacy of traditional medications.

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.

Mild hyperbaric oxygen for the early improvement of mood disturbance induced by high-intensity exercise

BACKGROUND

Excessive training stress can result in decreased performance and deep fatigue due to hormonal changes. There are few available data on recovery methods for mood disturbance, especially fatigue, after high-intensity training. This study, therefore, aimed to examine the effects of mild hyperbaric oxygen at 1.3 atmospheres absolute with 31% oxygen on mood disturbance induced by high-intensity exercises.

METHODS

Ten healthy adult men participated in and completed 2 trials: the control (CON) trial and the mild hyperbaric oxygen (MHO) trial. In a randomized crossover design, each subject cycled for 60 min at the physical work capacity at 75% of their maximal heart rate and were subsequently exposed to the CON and MHO conditions for 60 min as the recovery period.

RESULTS

During the 20 to 40 min recovery time points, the average change ratio of heart rates was lower in the MHO trial than in CON (p < 0.05). We observed that the fatigue-inertia, tension-anxiety, and total mood disturbance Profile of Mood States (POMS) scores decreased 60 min post-exercise in the MHO trial, but no differences of these score were observed in the CON trial. There were no differences in oxidative stress, derived-reactive oxygen metabolites, and biological antioxidant potential between both trials. These results suggest that impaired mood states induced by high-intensity exercise can be improved early by MHO without any changes in oxidative stress. This improvement may be associated with decreased heart rate secondary to MHO exposure after the high intensity exercise.

CONCLUSIONS

We conclude that MHO can improve mood disturbances, especially in the fatigue-inertia and tension-anxiety domains, after high-intensity exercise. This study suggest that MHO is potentially an effective recovery method for mood states after high-intensity training.

Audio Described vs. Audiovisual Porn: Cortisol, Heart Rate and Engagement in Visually Impaired vs. Sighted Participants

Audio description remains the cornerstone of accessibility for visually impaired audiences to all sorts of audiovisual content, including porn. Existing work points to the efficacy of audio description to guarantee immersion and emotional engagement, but evidence on its role in sexual arousal and engagement in porn is still scant. The present study takes on this challenge by comparing sighted and visually impaired participants’ experiences with porn in terms of their physiological response [i.e., cortisol and heart rate (HR)] and self-report measures of affect [Positive and Negative Affect Schedule (PANAS); Watson et al., 1988], anxiety [State-Trait Anxiety Inventory (STAI); Spielberger et al., 1970], sexual reactivity and arousal [Sexual Inhibition/Sexual Excitation Scale (SIS/SES); Moyano and Sierra (2014); and the Ratings of Sexual Arousal (RSA); Mosher (2011)], and narrative engagement or transportation [The Transport Narrative Questionnaire, Green and Brock (2013)]. 69 Spanish participants were allocated into three different groups: 25 sighted participants who watched and heard the porn scenes in their audio-visual version (AV); 22 sighted participants who listened to the audio described version without images (AD); and 22 visually impaired participants who also listened to the audio described version without images (ONCE). Overall, results on physiological and self-report measures revealed no significant differences between groups or different versions of the clips. The analysis of cortisol reactivity to porn as the maximum increase or decrease in cortisol (t+12) with respect to baseline values (t−20) revealed no significant differences between the groups, but pointed to a higher percentage of non-responders than responders in the three groups, the highest being found in the ONCE group. As for participants’ cardiac response to the clips, no significant differences were found across the groups, with the highest HR levels being registered in the baseline phase. Self-report measures revealed significant between-group differences in negative affect. The ONCE group displayed the highest pre-task levels of negative affect and was the only group that showed a decrease in negative affect after exposure to the clips. Sighted and visually impaired participants reported to be moderately aroused and immersed in the films, regardless of exposure to AV or AD porn. In addition, correlations found between participants’ levels of self-report sexual arousal and transportation and post-task affect pointed to a positive relationship between exposure to porn and perceived levels of sexual arousal and affect. Results from the study reflected the efficacy of audio description in providing sighted and visually impaired audiences with a similar experience to that offered by original AV porn scenes. This study is exploratory but provides valid, initial groundwork for further research on the impact of audio description on porn reception.

Salivary markers of stress system activation and social withdrawal in humans

Social withdrawal is an early and common feature of psychiatric disorders. Hypothalamic-pituitary-adrenal (HPA)-axis activation through increased salivary cortisol (sC) and sympathetic activation through increased salivary alpha-amylase (sAA) may play a role. We aimed to study whether the link between increased sC and sAA on the one hand and depression on the other hand is mediated by social withdrawal. In this cross-sectional, observational study, sC and sAA measures were measured in seven saliva samples in 843 participants (231 psychiatric patients and 612 healthy controls). Social withdrawal was assessed through the Brief Symptom Inventory (BSI)-, the Short Form 36-, and the Dutch Dimensional Assessment of Personality Pathology social withdrawal subscales, and analyzed using linear regression and mediation analyses. On average, participants were 44.0 years old (SD = 12.8; 64.1% female). Basal and diurnal sAA were unrelated to any social withdrawal scale and depression. Certain sC measures were positively associated with the BSI social withdrawal subscale (i.e., area under the curve with respect to the increase, beta = 0.082, p = 0.02; evening sC value: beta = 0.110, p = 0.003; and mean sC value: beta = 0.097; p = 0.01). We found limited support for statistical mediation by social withdrawal (measured using a composite social withdrawal score) on the relationship between evening sC and depression. Thus, although we found no support for a role of basal and diurnal sAA in social withdrawal, HPA-axis activation may partly aggravate social withdrawal in depressive disorders.

Autonomic Nervous System Response to Psychosocial Stress in Anorexia Nervosa: A Cross-Sectional and Controlled Study

To foster understanding in the psychopathology of patients with anorexia nervosa (P_AN) at the psychological and physiological level, standardized experimental studies on reliable biomarkers are needed, especially due to the lack of disorder-specific samples. To this end, the autonomic nervous system (ANS) response to a psychosocial stressor was investigated in n = 19 P_AN (BMI: 18.7 ± 3.3 kg/m²), age, and gender-matched to n = 19 healthy controls (HC; BMI: 24.23 ± 3.0 kg/m²). For this purpose, heart rate (HR) and heart rate variability (HRV) parameters were assessed in a cross-sectional study design under two experimental conditions: (1) rest and (2) stress (Trier Social Stress Test). In addition, psychological indicators of stress were assessed. An 2 × 2 × 8 ANOVA demonstrated similar HR and HRV patterns (except LF-HRV) between P_AN and HC at rest. Under stress, P_AN (vs. HC) demonstrated a blunted HR [condition^*time^*group: F_{(2.91, 104.98)} = 9.326, p = 0.000, η² = 0.206] and an attenuated HRV response (reduced SNS/PNS reactivity). Significant effects of stress appraisal (SA) and BMI on HRV-reactivity were revealed. SA on SDNN = Condition^*time^*SA = F_{(4.12, 140.15)} = 2.676, p = 0.033, η² = 0.073. BMI on LF/HF-Ratio = Condition^*time^*BMI = F_{(3.53, 60.16)} = 3.339, p = 0.019, η² = 0.164. Psychological indices suggested higher levels of chronic and appraised stress in P_AN relative to HC. Additional analyses demonstrated that ED-symptoms are highly correlated with the latter constructs, as well as with psychological burden, but not with weight. Further, it was shown that abnormalities in reactivity persisted despite normalized ANS activity. Overall, we suggested that besides weight recovery, improvement in stress appraisal could be beneficial for cardiac health. In this light, a combination of therapy (e.g., development and activation of coping skills, cognitive reappraisal) and biofeedback training may improve treatment outcomes and regulate stress reactivity.

Elevated Activity of the Sympathetic Nervous System Is Related to Diminished Practice Effects in Memory: A Pilot Study

Background:

Reductions in memory practice effects have gained interest as risk factor for future cognitive decline. Practice effects vary with age and can be moderated by factors such as individual variability in arousal or stress experience acting as an additional cognitive load.

Objective:

In the current pilot study, we examined whether sympathetic nervous system activation moderates the relationship between age and practice effects.

Methods:

Thirty cognitively healthy individuals aged 40–70 years performed a mnemonic discrimination task twice. Salivary alpha amylase (sAA) samples were obtained at different time points as a proxy of sympathetic activity. Spearman correlations examined the relation between practice effects and sAA. Subsequently, age by sAA interactions on practice scores were explored with bootstrapped linear regression models. Additionally, participants were divided in learners (exhibiting practice effects) and non-learners based on the difference in mnemonic discrimination performance.

Results:

Higher age and baseline SNS activity were independently related to lower practice effects. The non-learners showed significantly higher sAA scores at all time points compared to learners. Among the learners, baseline-adjusted lower levels of sAA after encoding were associated with greater practice effects, particularly in middle-aged individuals. No such interaction was observed for non-learners.

Conclusion:

These results show that higher baseline sympathetic activation is associated with worse practice effects independently of age. Additionally, in a subgroup of middle-aged learners practice effects were observed when sympathetic activity remained low during learning. These findings suggest that elevated sympathetic nervous system activation may be a promising indicator of imminent cognitive decline.

Changes in Salivary Amylase and Glucose in Diabetes: A Scoping Review

BACKGROUND AND OBJECTIVE

Diabetes mellitus (DM) is a common long-term disease which can be related with salivary amylase levels. DM has recently been associated with salivary amylase diagnostics that could further impair diagnoses in the diabetic population, as well as being an interesting alternative to traditional methods of determine glucose levels. The main advantage of this method is related to the fact that it is a fast diagnostic method. The DM population experiences changes to their metabolism which affects their salivary parameters, making this an alternative procedure for diagnosis and follow-up of the illness due to the non-invasive nature of salivary analyzes. The objective of this review is to summarize the evidence regarding the changes in salivary amylase and glucose levels, and their relationship with blood markers of glycemic control used in clinical settings such as blood glucose and glycated hemoglobin. The differences in salivary amylase levels depending on the method of saliva collection under fasting or non-fasting conditions. The changes in salivary amylase depends on the type of diabetes, the type of insulin treatment or the quality of glycemic control.

CONCLUSIONS

Salivary amylase concentration is increased in diabetic patients in most of the studies and salivary glucose concentration in all studies in both fasting and non-fasting (post-prandial) conditions. Salivary amylase and glucose concentration represent potential non-invasive biomarkers to evaluate glycemic control and clinical management of diabetic patients, although it is necessary to evaluate the influence of potential modulating factors such as age, duration diseases, sex and the effects of pharmacological treatments in these outcomes which remained to be elucidated.

Salivary cortisol and alpha-amylase daily profiles and stress responses to an academic performance test and a moral cognition task in children with neurodevelopmental disorders

There is evidence that children with neurodevelopmental disorders may exhibit atypical responses to stress and alterations in concentrations and diurnal secretion of stress hormones. We assessed diurnal profiles and stress responses of salivary cortisol and alpha-amylase (sAA) in children with attention-deficit hyperactivity disorder (ADHD), autism spectrum disorder (ASD) and specific learning disorder (SLD) compared to typically developing children (TD). A total of 157 children of both sexes, aged between 6 and 12 years old, took part in the study distributed into four groups: ADHD (N = 34), ASD (N = 56), SLD (N = 43) and TD (N = 24). Salivary samples were collected at three time points during a day, as well as before and 5 min after an academic performance test and a moral cognition task. ADHD children had lower evening and diurnal sAA levels, adjusted for age. Also, ASD children showed lower diurnal sAA secretion, adjusted for age. The mean percentage change for salivary cortisol and sAA after both tests did not differ between the groups. In conclusion, we demonstrated alterations in diurnal autonomic functioning in children with ADHD and ASD, while hypothalamic-pituitary-adrenal axis functioning did not differ between the clinical and the comparison groups.

Externalizing behavior and stress system functioning in infants exposed to early adversity: A multi-system exploration

Children who experience early adversity often show alterations across multiple stress response systems, including the hypothalamic-pituitary-adrenal (HPA) axis and autonomic nervous system (ANS). Changes in the diurnal rhythm of salivary cortisol (a marker of HPA axis functioning) and alpha-amylase (a marker of ANS functioning) may increase their probability of developing behavior problems. The goal of this study is to examine how these analytes may interact to predict externalizing behavior in infants exposed to early stress. Participants included 179 parents and their 6- to 20-month old infants recruited from a low-income neighborhood. Parents reported on their infants' externalizing behaviors and collected saliva samples from their children at wake-up and bedtime over three days. Diurnal cortisol and alpha-amylase were modeled using latent difference scores. Four models were tested examining the effects of cortisol and alpha-amylase morning values and slopes, as well as their interactions, on externalizing behavior. Results showed a significant interaction effect of cortisol and alpha-amylase morning values, such that low morning cortisol was associated with decreased externalizing behavior when morning alpha-amylase was high but not low. These findings highlight the importance of examining multiple systems when characterizing the physiological correlates of externalizing behavior among infants experiencing adversity.

Perceived Social Support and Children's Physiological Responses to Stress: An Examination of the Stress-Buffering Hypothesis

OBJECTIVE

The current study aimed to examine the stress-buffering effect of children's perceived social support on their hypothalamic-pituitary-adrenocortical axis and autonomic nervous system reactivity to an acute laboratory stressor.

METHODS

A sample of 150 children (aged 9-13 years, mean [standard deviation] age = 10.69 [0.93] years, 74 girls) reported perceived social support, stressful life events, and underwent the Modified Trier Social Stress Test, during which six saliva samples were collected. A two-piece multilevel growth curve model with landmark registration was used to detect trajectory differences in the reactivity and recovery phases of the stress response and account for individual variation in the timing of poststressor peak hormone concentrations.

RESULTS

The interaction between stressful life events and perceived social support significantly predicted poststressor peak cortisol levels (β = 0.0805, SE = 0.0328, p = .015) and cortisol recovery slope (β = -0.0011, SE = 0.0005, p = .040). Children with more life events and low social support exhibited the lowest poststressor peak cortisol levels and the flattest cortisol recovery slope. In contrast, children high in stressful life events and high in social support displayed cortisol response profiles more similar to those of children with low stressful life events. Conversely, there were no statistically significant two-way interactions of stressful life events and perceived social support on salivary α-amylase parameters (i.e., poststressor peak [p = .38], reactivity slope [p = .81], and recovery slope [p = .32]).

CONCLUSIONS

These results provide preliminary evidence for the buffering effect of children's perceived social support on the association between life stress and hypothalamic-pituitary-adrenocortical axis response profiles.

Associations Between Cardiorespiratory Fitness and Endocrine, Autonomous and Psychological Stress Reactivity in Male Adolescents

Abstract. High stress burden during adolescence can have severe long-term health consequences. While some studies reported that adults with higher fitness levels show lower stress reactivity, research on adolescents is scarce. Accordingly, the aim of the present study was to investigate the association between cardiorespiratory fitness and physiological and psychological stress reactivity in male adolescents. Forty-three healthy, male adolescents aged 16–20 years underwent the Physical Working Capacity 170 bicycle ergometer test to determine cardiorespiratory fitness. The Trier Social Stress Test (TSST) was used to trigger a stress reaction, which was measured physiologically with changes in salivary cortisol and alpha-amylase concentrations, and psychologically using self-rated changes in state-anxiety. Under consideration of potential confounders, hierarchical regression analyses were calculated for each outcome. For cortisol and psychological stress reactivity, fitness did not significantly explain variance. However, 28% of variance in alpha-amylase reactivity were explained by fitness and sleep complaints [adjusted R2 = .28, F(2, 36) = 8.36, p = .001], with 16% of variance explained by fitness alone (β = −.41, p = .006). Accordingly, higher fitness was associated with lower stress reactivity of the autonomous nervous system in male adolescents. The promotion of cardiorespiratory fitness may therefore be considered an important factor in preventing negative health consequences of stress in this age group.

Effects of nightmares on the cortisol awakening response: An ambulatory assessment pilot study

Previous studies have reported an association between sleep-related factors such as sleep duration, sleep quality and time of awakening with the cortisol awakening response (CAR). Preliminary evidence suggests that frequent nightmares are associated with a blunted CAR. In the present pilot study we investigated the effect of acute nightmares on the CAR and the cortisol profile of the subsequent day using a within-subject ambulatory assessment study design. Thirty healthy volunteers who reported frequent nightmares enrolled in the study. Over a period of 14 days, salivary samples in addition to sleep-related and state variables were collected at home over the day. Salivary profiles of free cortisol and alpha amylase for up to two days following a nightmare were compared to those following a neutral dream. Overall, mood and health were decreased and the CAR was elevated following nightmares compared to neutral dreams. No differences were found for alpha amylase and for all variables over the remaining part of the day. Results suggest that sleep-related factors such as the occurrence of nightmares account for a certain amount of variance observed in the CAR. This has important methodological implications for CAR studies in general and might have even more relevance for studies in clinical populations suffering from chronic sleep disturbances.

Treatment Response Biomarkers in Anxiety Disorders: From Neuroimaging to Neuronally-Derived Extracellular Vesicles and Beyond

Multiple and diverse psychotherapeutic or psychopharmacologic treatments effectively reduce symptoms for many patients with anxiety disorders, but the trajectory and magnitude of response vary considerably. This heterogeneity of treatment response has invigorated the search for biomarkers of treatment response in anxiety disorders, across the lifespan. In this review, we summarize evidence for biomarkers of treatment response in children, adolescents and adults with generalized, separation and social anxiety disorders as well as panic disorder. We then discuss the relationship between these biomarkers of treatment response and the pathophysiology of anxiety disorders. Finally, we provide context for treatment response biomarkers of the future, including neuronally-derived extracellular vesicles in anxiety disorders and discuss challenges that must be overcome prior to the debut of treatment response biomarkers in the clinic. A number of promising treatment response biomarkers have been identified, although there is an urgent need to replicate findings and to identify which biomarkers might guide clinicians in selecting from available treatments rather than just simply identifying patients who may be less likely to respond to a given intervention.

Cranial osteopathic treatment and stress-related effects on autonomic nervous system measured by salivary markers: A pilot study

BACKGROUND

Variations in the concentration of salivary alpha amylase (sAA) may indicate a change in the autonomic nervous system functionality. In osteopathic medicine it has long been stated that the osteopathic manipulative treatment (OMT) can modulate the autonomic nervous system. Studies carried out on the compression of the fourth ventricle (CV4) have shown a positive effect in reducing the sympathetic tone. The goal of this pilot study is measuring the physiological response of the sAA levels after CV4 technique.

METHODS

90 subjects were randomly assigned to a sham, a control or a CV4 group. Randomization accounted for sex and score in the STAI-2 (form Y) questionnaire. Each subject completed the STAI-1 (form Y) questionnaire to evaluate the anxiety of the moment. sAA activity and saliva flow rate were measured. Saliva was collected before, immediately after and 30 min after treatment.

RESULTS

Within group analysis revealed that sAA activity increased significantly immediately after the technique application only in the CV4 group (p = 0,05). Between groups analysis show a significant difference of the sAA activity in the CV4 group respect the control group (p < 0,05), but no significant difference between CV4 and sham group (p > 0,05). The effect in the CV4 group after the intervention is highly variable and appeared to be related to the level of stress measured with the STAI-Y1 questionnaire (p = 0,002).

CONCLUSIONS

This study shows a positive effect of the CV4 procedure on sAA activity even if not significantly different from the sham procedure, probably due to the confounding effect of stress variability between groups.

Towards an understanding of neurophysiological self-regulation in early childhood: A heuristic and a new approach

Self-regulation in early childhood encompasses both "top down," volitional processes, as well as the "bottom up" activity of three neurophysiological systems: the parasympathetic nervous system (PNS), the sympathetic nervous system (SNS), and the hypothalamic-pituitary-adrenal (HPA) axis. In this paper we briefly review the structure, function, and early development of each of these systems and then explain why neurophysiological self-regulation is most accurately defined as a function of their joint activity. We note that while there are a number of predictive models that employ this definition, the field would benefit from a straightforward heuristic and aligned methods of visualization and analysis. We then present one such heuristic, which we call neurophysiological space, and outline how it may facilitate a new, collaborative approach to building a better understanding of self-regulation in early childhood. We conclude with a presentation of early education as one setting in which our heuristic and methods could be applied.

Salivary Cortisol and α-Amylase Production at Awakening is Associated with Positivity (POS) Levels in Healthy Young Subjects

A large variety of positive outcomes including social adjustment, psychological well-being and health, have been recently closely associated with positivity (POS). On the assumption that differences in the POS degree might be associated with different individual neuroendocrine assets that enables people to cope effectively with stress, the present study examined the association between POS, salivary cortisol and α-Amylase (α-Amy) production in a group of healthy male volunteers university students, respectively scoring high (POS-H, N = 10) and low (POS-L, N = 10) in POS. Participants were selected from a larger sample of 300 students of the Medical School at Sapienza University of Rome on the basis of their positivity level: POS was analysed and the upper and lower 25% were invited to participate in this new study. The findings report a distinct salivary cortisol and α-Amy production in the study population: in comparison to the POS-H group, the POS-L subjects presented a lower salivary cortisol awake response (CAR) and a flattened α-Amy production at 30 and 60 min after awakening. In addition, salivary cortisol and α-Amy areas under the curve (AUCs), which were calculated as indicators of the two subclinical biomarkers production during the first hour after awakening, resulted significantly lower in the POS-L group in comparison to the POS-H group. Further studies on larger and different populations are needed to definitively confirm that the different cortisol and α-Amy secretion patterns between POS-H and POS-L individuals is associated with a potentially better capacity to preserving an adequate quality of life in individuals being equipped with a system apparently able to better respond to external and/or internal stimuli. Lastly, a better understanding of the biological correlates of POS is crucial to design psychological interventions able to take advantage of individuals’ assets and thus to integrate and strengthen the efficacy of traditional medications.

Where Do We Stand in the Domestic Dog ( Canis familiaris ) Positive-Emotion Assessment: A State-of-the-Art Review and Future Directions

Although there have been a growing number of studies focusing on dog welfare, the research field concerning dog positive-emotion assessment remains mostly unexplored. This paper aims to provide a state-of-the-art review and summary of the scattered and disperse research on dog positive-emotion assessment. The review notably details the current advancement in dog positive-emotion research, what approaches, measures, methods, and techniques have been implemented so far in emotion perception, processing, and response assessment. Moreover, we propose possible future research directions for short-term emotion as well as longer-term emotional states assessment in dogs. The review ends by identifying and addressing some methodological limitations and by pointing out further methodological research needs.

Comparative evaluation of salivary alpha amylase level for assessment of stress during third molar surgery with and without piano music and co-relation with pain catastrophizing scale: an in vivo study

Objectives

Preoperative nervousness and anxiety are frequently encountered by individuals who undergo extractions of impacted wisdom teeth. The aim of the present study is to evaluate salivary alpha amylase (sAA) level in patients for assessment of stress during third molar surgery while listening to piano music and to determine its co-relation with pain catastrophizing scale (PCS).

Materials and Methods

Seven patients (four males and three females) indicated for surgical extraction of bilaterally impacted mandibular third molars were included. Pre-surgical patient assessments were completed, and three samples of saliva were collected during surgery—one at baseline, one 30 minutes after commencement of surgery, and one after suturing. Assessment was performed on both sides separately with and without piano music, and the samples were assessed for sAA level and correlated with the patient’s self-reported PCS.

Results

Statistically significant results were obtained in patients who underwent surgical extraction while listening to piano music (P=0.046). The correlation of sAA level with PCS was not significant.

Conclusion

Music demonstrated a beneficial effect on lowering the levels of stress and anxiety that a patient exhibits during any surgical procedure, and sAA can be a useful biomarker for similar assessments.

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.

Stress & executive functioning: A review considering moderating factors

A multitude of studies investigating the effects of stress on cognition has produced an inconsistent picture on whether - and under which conditions - stress has advantageous or disadvantageous effects on executive functions (EF). This review provides a short introduction to the concept of stress and its neurobiology, before discussing the need to consider moderating factors in the association between stress and EF. Three core domains are described and discussed in relation to the interplay between stress and cognition: the influence of different paradigms on physiological stress reactivity, individual differences in demographic and biological factors, and task-related features of cognitive tasks. Although some moderating variables such as the endocrine stress response have frequently been considered in single studies, no attempt of a holistic overview has been made so far. Therefore, we propose a more nuanced and systematic framework to study the effects of stress on executive functioning, comprising a holistic overview from the induction of stress, via biological mechanisms and interactions with individual differences, to the influence of stress on cognitive performance.

Neuroendocrine coordination and youth behavior problems: A review of studies assessing sympathetic nervous system and hypothalamic-pituitary adrenal axis activity using salivary alpha amylase and salivary cortisol

Externalizing and internalizing behavior problems can have deleterious psychosocial consequences for youth. Both sympathetic nervous system (SNS) and hypothalamic-pituitary adrenal (HPA) axis activity and reactivity may contribute to behavior problems but have largely been studied separately, with inconsistent findings. Because the SNS and HPA axis interact to carry out physiological processes (e.g., responding to stressors), considering SNS and HPA axis activity jointly may elucidate disparate findings. This review discusses studies that simultaneously assessed SNS and HPA axis (re)activity and youth behavior problems using measures of salivary alpha amylase (sAA) and salivary cortisol. Multiple patterns of SNS and HPA axis coordination were associated with problem behaviors, especially when considering individual differences and youth's psychosocial context. Importantly, many study findings may be artifacts of widespread methodological differences. The reviewed studies lay the foundation for future research on neuroendocrine coordination as a contributing factor to youth problem behaviors and some recommendations for future research are discussed.

Dose-Dependent Acute Effects of Everolimus Administration on Immunological, Neuroendocrine and Psychological Parameters in Healthy Men

The rapamycin analogue everolimus (EVR) is a potent inhibitor of the mammalian target of rapamycin (mTOR) and clinically used to prevent allograft rejections as well as tumor growth. The pharmacokinetic and immunosuppressive efficacy of EVR have been extensively reported in patient populations and in vitro studies. However, dose-dependent ex vivo effects upon acute EVR administration in healthy volunteers are rare. Moreover, immunosuppressive drugs are associated with neuroendocrine changes and psychological disturbances. It is largely unknown so far whether and to what extend EVR affects neuroendocrine functions, mood, and anxiety in healthy individuals. Thus, in the present study, we analyzed the effects of three different clinically applied EVR doses (1.5, 2.25, and 3 mg) orally administered 4 times in a 12-hour cycle to healthy male volunteers on immunological, neuroendocrine, and psychological parameters. We observed that oral intake of medium (2.25 mg) and high doses (3 mg) of EVR efficiently suppressed T cell proliferation as well as IL-10 cytokine production in ex vivo mitogen-stimulated peripheral blood mononuclear cell. Further, acute low (1.5 mg) and medium (2.25 mg) EVR administration increased state anxiety levels accompanied by significantly elevated noradrenaline (NA) concentrations. In contrast, high-dose EVR significantly reduced plasma and saliva cortisol as well as NA levels and perceived state anxiety. Hence, these data confirm the acute immunosuppressive effects of the mTOR inhibitor EVR and provide evidence for EVR-induced alterations in neuroendocrine parameters and behavior under physiological conditions in healthy volunteers.

Salivary Gland Dysfunction, Protein Glycooxidation and Nitrosative Stress in Children with Chronic Kidney Disease

This study is the first to evaluate protein glycooxidation products, lipid oxidative damage and nitrosative stress in non-stimulated (NWS) and stimulated whole saliva (SWS) of children with chronic kidney disease (CKD) divided into two subgroups: normal salivary secretion (n = 18) and hyposalivation (NWS flow < 0.2 mL min-1; n = 12). Hyposalivation was observed in all patients with severe renal failure (4-5 stage CKD), while saliva secretion > 0.2 mL/min in children with mild-moderate CKD (1-3 stage) and controls. Salivary amylase activity and total protein content were significantly lower in CKD children with hyposalivation compared to CKD patients with normal saliva secretion and control group. The fluorescence of protein glycooxidation products (kynurenine, N-formylkynurenine, advanced glycation end products), the content of oxidative damage to lipids (4-hydroxynonneal, 8-isoprostanes) and nitrosative stress (peroxynitrite, nitrotyrosine) were significantly higher in NWS, SWS, and plasma of CKD children with hyposalivation compared to patients with normal salivary secretion and healthy controls. In CKD group, salivary oxidation products correlated negatively with salivary flow rate, -amylase activity and total protein content; however, salivary oxidation products do not reflect their plasma level. In conclusion, children with CKD suffer from salivary gland dysfunction. Oxidation of salivary proteins and lipids increases with CKD progression and deterioration of salivary gland function.

Diurnal trajectories of salivary cortisol and α-amylase and psychological profiles in patients with central serous chorioretinopathy

It has been hypothesized that the occurrence of central serous chorioretinopathy (CSC) might be associated with stress. Therefore, our purpose was to investigate the diurnal trajectories of salivary cortisol and α-amylase (α-Amy) - markers of hypothalamic-pituitary-adrenal (HPA) axis and sympathetic-adrenal-medullary (SAM) system activity, respectively - and psychological profiles in idiopathic acute CSC. This cross-sectional observational case-control study, which included self-reported psychometric questionnaires, was formally approved by the Ethics Committee. Written informed consent was obtained from all participants. Home diurnal saliva collection was scheduled at several timepoints: at awakening, 30 and 60 min later, and at approximately 13:00 h and 20:00 h. Twenty consecutive male subjects with first-episode CSC attending the outpatient clinic of the Retina Medical Service at the Bietti Foundation were enrolled in the study. Twenty age-matched subjects were recruited as controls. After their initial enrollment, 3 subjects per group were excluded. The production of cortisol and α-Amy and the scores on the negative subscale of the Positive/Negative Affect Schedule, the Daily Hassles and Stress Scale and the Beck Depression Inventory were higher in the CSC group than in the control group. To estimate the diurnal trends in the production of salivary cortisol and α-Amy, an equation was derived for each group of the study population. The equations describing the interpolated regression lines gave salivary cortisol and salivary α-Amy slopes that were determined to be significantly different by Student's t-test (cortisol: t = 3.533, p < .001; α-Amy: t = 2.382, p = .018). Furthermore, the area under the curve with respect to the ground (AUC_G) was calculated to summarize repeated salivary biomarker measurements from 07:00 h to 08:00 h for assessment of the cortisol awakening response (CAR) and the α-Amy awakening response (AR). The diurnal cortisol AUC_G and diurnal α-Amy AUC_G were calculated from 07:00 h to 20:00 h. The CAR AUC_G values of the CSC patients were significantly higher than those of the controls. No differences between the two groups were detected for the α-Amy AR AUC_G. The present study adds novel information to the growing body of data suggesting that abnormal diurnal activity of the HPA axis and the SAM system is associated with CSC in susceptible individuals, providing ophthalmologists with a new chronobiological approach for these patients.

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.

Validity and reliability evidence of a point of care assessment of salivary cortisol and α-amylase: a pre-registered study

PURPOSE

The iPro Cube is a small portable point-of-care device designed to analyse salivary markers of stress in a user-friendly manner (e.g., fast, convenient). Our aim was to test the reliability and validity of the iPro Cube to measure salivary cortisol and α-amylase as compared to the common laboratory standard method (ELISA immunoassay) prior to and after moderate intensity exercise.

METHODS

The study was a repeated measures, pre-registered design, and statistical framework that incorporated prior knowledge directly into the estimation process. Twenty-nine individuals (age = 27.4 ± 6.6 y; body-mass = 70.8 ± 11.3 kg; height = 1.74 ± 0.92 m; 18 males) completed a single PWC75%HRmax, with repeated measures of salivary cortisol and -amylase pre, immediately post, and 30 min post-exercise.

RESULTS

Correlation between the iPro Cube and laboratory-based assessments of salivary cortisol was moderate-to-large (0.53 > r < 0.81) across all three testing points. In contrast, correlation between the iPro Cube and laboratory-based assessments of -amylase was small-to-moderate (0.25 > r < 0.46). We found a large correlation between duplicate samples of iPro Cube cortisol assessment (0.75 > r < 0.82), and a moderate-to-large correlation for -amylase (0.51> r < 0.77).

CONCLUSIONS

The iPro Cube is capable of taking measures of salivary cortisol that are moderately correlated to values obtained via ELISA immunoassay, however the unit underestimates salivary cortisol and overestimates salivary -amylase at rest and post-moderate intensity exercise. It is recommended that researchers continue using standard laboratory techniques to assess these salivary stress markers.

Effect of food contamination and collection material in the measurement of biomarkers in saliva of horses

This study aims to evaluate the effect of the presence of food and the material used in a panel of biomarkers in saliva of horses. For the food effect study, clean saliva was incubated with a known amount of food consisting of oats, hay or grass. Significant changes were observed when saliva was incubated with oats for total protein (P = .050) and phosphorus (P = .008), with grass for total protein (P = .037), salivary alpha-amylase (sAA, P = .018), total esterase (TEA, P = .018), butyrilcholinesterase (BChE, P = .037), adenosine deaminase (ADA, P = .037), and total bilirubin (P = .018), and with hay for sAA (P = .018), phosphorus (P = .037), γ-glutamyl transferase (gGT, P = .004), and creatine kinase (CK, P = .016). For the material-based collection study, saliva using a sponge and a cotton role at the same time were collected and compared. Lower values were obtained in clean saliva collected with cotton role compared to sponge for sAA (P = .030), TEA (P = .034), BChE (P = .003), gGT (P = .002) and cortisol (P < .001) In conclusion, the presence of food and the material used for its collection, can influence the results obtained when analytes are measured in saliva of horses.

Analytical Strategies in Lipidomics for Discovery of Functional Biomarkers from Human Saliva

Human saliva is increasingly being used and validated as a biofluid for diagnosing, monitoring systemic disease status, and predicting disease progression. The discovery of biomarkers in saliva biofluid offers unique opportunities to bypass the invasive procedure of blood sampling by using oral fluids to evaluate the health condition of a patient. Saliva biofluid is clinically relevant since its components can be found in plasma. As salivary lipids are among the most essential cellular components of human saliva, there is great potential for their use as biomarkers. Lipid composition in cells and tissues change in response to physiological changes and normal tissues have a different lipid composition than tissues affected by diseases. Lipid imbalance is closely associated with a number of human lifestyle-related diseases, such as atherosclerosis, diabetes, metabolic syndromes, systemic cancers, neurodegenerative diseases, and infectious diseases. Thus, identification of lipidomic biomarkers or key lipids in different diseases can be used to diagnose diseases and disease state and evaluate response to treatments. However, further research is needed to determine if saliva can be used as a surrogate to serum lipid profiles, given that highly sensitive methods with low limits of detection are needed to discover salivary biomarkers in order to develop reliable diagnostic and disease monitoring salivary tests. Lipidomic methods have greatly advanced in recent years with a constant advance in mass spectrometry (MS) and development of MS detectors with high accuracy and high resolution that are able to determine the elemental composition of many lipids.

Changes in Saliva Analytes Correlate with Horses' Behavioural Reactions to An Acute Stressor: A Pilot Study

Simple Summary

Emotionality is an individual characteristic defined as the propensity to respond to stress-inducing stimuli such as fear-inducing objects or social separation. Evaluation of emotionality in horses is important as it may impact their learning performance. Although emotionality is usually assessed by measuring behavioural patterns, biomarkers could provide additional information about stress response, especially with respect to its temporal dynamics. In this study, behavioural responses were measured as well as a panel of salivary biomarkers related to stress, including salivary alpha-amylase, lipase, total esterase, butyrylcholinesterase, adenosine deaminase, and cortisol, in riding horses after acute experimental stress (the sudden opening of an umbrella). We found significant changes in most of the salivary biomarkers evaluated after the induced stress, where increases in butyrylcholinesterase were more closely related to behavioural responses to acute stress and low salivary alpha-amylase values were more closely related to quietness behaviours. Therefore, this preliminary research provides information about the relationship between behaviour patterns and biomarkers of stress in saliva in horses, and opens the possibility of wider use of selected biomarkers in saliva, such as butyrylcholinesterase or alpha-amylase, for the evaluation of acute stress in horses.

Abstract

Acute stress induces an array of behavioural reactions in horses that vary between individuals. Attempts to relate behavioural patterns and physiological responses have not always given clear-cut results. Here, we measured the changes in a panel of salivary components: salivary alpha-amylase (sAA), lipase, total esterase (TEA), butyrylcholinesterase (BChE), adenosine deaminase (ADA), and cortisol, and their potential link with horses’ behaviours after acute stress. Saliva samples were collected in nine riding horses subjected to a test consisting of opening an umbrella. Saliva sampling was obtained at a basal time point in the stall (T1), in the test indoor arena (T2), at a time of stress (T3), and 30 min (T4) and 60 min (T5) later. The horses’ behaviour was recorded at T3 for 1 min. sAA, lipase, TEA, and BChE showed significant changes along time, increasing at T3 for BChE, and decreasing at T4 for sAA and BChE. Butyrylcholinesterase appeared to be the most reliable predictor of behavioural responses, as it correlated with the index of emotionality, of laterality, and the occurrence of alarm signals, while sAA decreased when horses expressed quieter behaviours. These first results bring promising lines for novel, more precise physiological markers of acute stress in horses that can bridge the gap between behaviour and physiology.

Repeated stress leads to enhanced cortisol stress response in child social anxiety disorder but this effect can be prevented with CBT

Social anxiety disorder (SAD) is associated with continual social stress in everyday life. Two physiological components of stress are the hypothalamus-pituitary-adrenal axis, as captured by cortisol reactivity, and the autonomous nervous system, as captured by salivary alpha amylase (sAA) reactivity. In children with SAD, initial evidence points to dysregulated physiological stress reactivity for both systems. Furthermore, hardly any studies have assessed stress reactivity twice, including exploring possible changes after cognitive behavioral therapy (CBT). Children with SAD (n = 65; aged 9-13 years) and healthy controls (HCs, n = 55) participated in a social stress task (Trier Social Stress Test for Children, TSST-C), which was repeated with children with SAD after either 12 sessions of CBT or a waiting period to explore possible habituation or sensitization effects. Before treatment, children in the SAD and HC groups did not differ in their cortisol stress reactivity toward the TSST-C but did differ in their sAA response with a more pronounced response in the SAD group. After treatment, children with SAD in the waitlist group differed from children with SAD in the CBT group by showing stronger cortisol reactivity and a higher responder rate, indicative of a possible sensitization to stress. No difference was found for sAA. Future research should compare children with SAD and HC children concerning the effect of repeated stress on sensitization.

Salivary alpha-amylase enzyme is a non-invasive biomarker of acute stress in Japanese macaques (Macaca fuscata)

Salivary alpha-amylase (sAA) enzyme functions as a digestive enzyme in many species that consume starch in their diet. Human studies have also revealed that sAA enzyme activity levels are positively correlated with the release of the stress hormone norepinephrine, allowing sAA to act as a biomarker for sympathetic nervous system activity. Recent non-human primate studies have incorporated sAA as a physiological stress marker. However, no published reports have investigated the time course of sAA from a stressful event to return to baseline levels in non-human primates. Furthermore, no validation of sAA as a stress biomarker has been reported for Japanese macaques (Macaca fuscata). This study had two primary aims: (1) to develop a systematic method for non-invasive saliva collection and, (2) to investigate sAA as a biomarker of acute stress in M. fuscata in order to better understand its acute stress-related characteristics. We developed a non-invasive method for cooperative saliva collection using positive reinforcement training (PRT) and tracked individual progress over 595 trials in ten individually housed Japanese macaques. We detected sAA enzyme in M. fuscata via kinetic reaction assay, then performed 22 acute stress tests. Four tests met conditions for interpreting sAA in response to an acute stressor and these results show that on average sAA activity rapidly increased post-stressor (mean ± SD = 4.2 ± 0.9 min) and returned to baseline shortly thereafter (10.4 ± 0.6 min). Our report reveals for the first time the temporal dynamics of sAA when applying acute stress to Japanese macaques and could be a useful tool for assessing animal welfare.

Exploratory Investigation of Infrared Thermography for Measuring Gorilla Emotional Responses to Interactions with Familiar Humans

Simple Summary

Interactions between zoo professionals and animals, such as positive reinforcement training, occur regularly and are thought to be enriching for animals. However, there is little empirical information on how animals perceive these interactions or on the interactions’ effects on animals’ emotional states. Our objective was to assess the effectiveness of infrared thermography for measuring the emotional responses of three western lowland gorillas at the Detroit Zoo to routine interactions (positive reinforcement training and cognitive tasks) with familiar humans. In addition to thermal images, we collected saliva samples for hormone analysis before and after human–animal interactions and a control condition, and we recorded behavioral data during all conditions. Nasal temperatures consistently decreased for two gorillas during interactions, while the third gorilla showed repeated increases. The behavior of all three gorillas suggested that they were engaged in the interactions, without exhibiting behaviors that could indicate negative welfare impacts. Oxytocin and cortisol both decreased following all conditions, including the control, and were thus equivocal for interpreting the meaning of the changes in nasal temperature. As mixed results in previous research show, infrared thermography may detect emotional arousal; however, additional indicators are necessary to determine the valence of the observed changes. The variability in responses we observed do not lend themselves to making firm conclusions about the validity of infrared thermography (IRT) for measuring emotion in this context or about how these gorillas responded to interactions. Challenges and suggestions for future studies using infrared thermography to examine interactions between humans and zoo animals are discussed.

Abstract

Interactions between zoo professionals and animals occur regularly and are believed to be enriching for animals. Little empirical information exists on how animals perceive these interactions, and particularly how the interactions affect the emotional states of animals. Infrared thermography (IRT) has shown some promise in the assessment of emotions in a variety of species, but further research is needed to determine if this method is useful in a zoo setting. We conducted a pilot study to determine if IRT is a valid measure of the emotional responses to routine interactions (positive reinforcement training and cognitive tasks, compared to a control condition) with familiar humans on three western lowland gorillas at the Detroit Zoo. We measured nasal temperatures associated with emotional change using IRT. To examine the validity of the IRT data, we collected saliva samples for hormone analysis before and after each condition, in addition to behavioral data during the interactions and control condition. Decreases in nasal temperatures for two gorillas and an increase in the third indicate that arousal changed consistently within individuals following the interactions but not the control condition. Pre-post cortisol levels and oxytocin concentrations decreased for all conditions, but the decreases seen did not differ among the conditions. The gorillas were highly engaged in the interactions, and two produced more grumble vocalizations during the human-animal interactions (HAIs) compared to the control condition. Additionally, the gorillas performed self-directed behaviors more often during the control condition, also suggesting HAIs were not a negative experience. In summary, we were able to measure changes in arousal using IRT, but we were unable to determine the emotional valence of these changes based on the additional indicators employed. Additionally, the inconsistency across these measures precluded firm conclusions about either the validity of IRT for measuring emotion in this context or how the interactions impacted these gorillas. These findings highlight the challenges of using IRT to measure emotional states in non-human animals, and we discuss further steps necessary to apply this method in future studies.

Evaluation of the socially evaluated cold-pressor group test (SECPT-G) in the general population

Background

In stress research, economic instruments for introducing acute stress responses are needed. In this study, we investigated whether the socially evaluated cold-pressor group test (SECPT-G) induces salivary alpha-amylase (sAA) and/or cortisol responses in the general population and whether this is associated with anthropometric, experimental, and lifestyle factors.

Methods

A sample of 91 participants from the general population was recruited. Salivary cortisol and sAA levels were assessed prior to (t₀), immediately after (t₁), and 10 min after the SECPT-G (t₂).

Results

A robust cortisol increase was found immediately after the SECPT-G, which further increased between t₁ and t₂. This was independent of most of the control variables. However, men showed a trend toward higher cortisol increases than women (p = 0.005). No sAA responses were found at all. However, sAA levels were dependent on measurement time point with highest levels between 9 pm and 9:30 pm. Participants who immersed their hands into the ice water for the maximally allowed time of 3 min showed higher sAA levels at all time points than participants who removed their hands from the water earlier.

Conclusions

We conclude that the SECPT-G is a good means of an acute stress test when cortisol—but not necessarily sAA—responses are intended.

Variation of human salivary alpha-amylase proteoforms in three stimulation models

OBJECTIVES

To evaluate the sAA proteoforms' expression during different stimulation situations.

MATERIALS AND METHODS

This study evaluated the salivary alpha-amylase (sAA) proteoforms' behavior by western blot (WB) analysis and high-resolution mass spectrometry (LC-MS/MS) in different situations that produce increases in sAA activity. For this purpose, six healthy women with a similar body mass index, age, and fit, underwent different sAA stimulation tests, such as acetic acid stimulation, psychological stress using the standardized Trier social stress test, and physical effort using the Cooper treadmill test.

RESULTS

The three models showed an increase in sAA activity. The WB demonstrated seven common bands observed in the six women (band one at 59 kDa, two at 56 kDa, three at 48 kDa, four at 45 kDa, five at 41 kDa, six at 36 kDa, and seven at 14 kDa), in which sAA protein was identified. The individual WB analysis showed that band two, which corresponded to the native non-glycosylated sAA proteoform, had a higher increase after the three sAA stimulation inducers, and this band was also the only proteoform correlated with sAA activity (r = 0.56, P = 0.001). In addition, when the label-free quantification analysis was performed, the different proteoforms showed different responses depending on the type of stimulation.

CONCLUSIONS

This preliminary study showed that the diverse sAA proteoforms' expression depends on the different stimulation models.

CLINICAL RELEVANCE

This study opens new perspectives and challenges for the use of the different alpha-amylase proteoforms as possible biomarkers in addition to the sAA activity.

Subjective unpleasantness of malodors induces a stress response

Unpleasant odors impair our mood and may affect physical health, even when the odorants are not toxic. A possible cause for such negative effects is stress induced by odors; however, whether the unpleasantness itself elicited stress or not has not been clear. Thus, we examined whether unpleasantness of odors induced the stress responses of emotion, the hypothalamic-pituitary-adrenal (HPA) axis, and the sympathetic nervous system (SNS). Six experiments were conducted, where salivary cortisol or salivary alpha amylase (sAA), markers for activities of the HPA and the SNS, respectively, were measured, along with subjective ratings of odors and emotion. First, the responses to three malodors listed in the Offensive Odor Control Law in Japan were examined. While these odors were rated as unpleasant, and exposure to them increased anxiety, no response of the HPA was observed (experiment 1, n = 69). In contrast, an increase of the SNS activity was observed after exposure to two of the three malodors, while the SNS did not respond to pleasant odors (experiments 2-4, n = 35, 34 and 30). To examine the effect of unpleasantness further, the SNS response was examined while subjective unpleasantness of odors was manipulated by adding negative verbal information (experiment 5, n = 92), or by mixing in a pleasant odor (experiment 6, n = 35). The SNS responses upon inhalation of the same odorous substances were found to be dependent on whether they were perceived as unpleasant. Finally, a correlation analysis on the pooled data from experiments 2-6 showed that the odor-elicited SNS activity and anxiety were strongly correlated with perceived unpleasantness of odors. These results suggest that subjective unpleasantness of odors per se can induce the stress response of emotion and the SNS.

Prospective memory under acute stress: The role of (output) monitoring and ongoing-task demands

Prospective memory (PM) refers to the ability to postpone retrieval and execution of intended actions until the appropriate situation (PM cue) has come, while engaging in other ongoing activities or tasks. In everyday live we often perform PM tasks in stressful situations. While it has been shown that acute stress does not impair PM-cue identification and intention retrieval, little is known about acute stress effects on PM performance and memory for having performed an action (output monitoring) under varying ongoing-task demands. Here we investigated this in eighty healthy participants who performed event-based PM tasks during low- and high-demanding ongoing working memory tasks after having undergone either a standardized stress induction (Maastricht Acute Stress Test) or a standardized control protocol. Successful stress induction in the stress group compared to the no-stress group was confirmed by increased salivary cortisol, an indicator of stress-related hypothalamus-pituitaryadrenal axis activity, throughout the event-based PM tasks. Nevertheless, not-only PM-cue identification but also output monitoring remained fully intact after stress induction. The absence of these effects was independent of ongoing-task demands. Nonetheless, we replicated recent findings of a stress-induced reduction in performance cost of monitoring for PM-cue occurrences. Taken together our findings suggest that acute stress alters PM monitoring by enhancing selective attention, decreasing PM response thresholds or by shifting performance towards more automatic processes in PM, while not affecting PM-cue identification and output monitoring.

Enhancing memory with stress: Progress, challenges, and opportunities

Stress can strongly influence what we learn and remember, including by making memories stronger. Experiments probing stress effects on hippocampus-dependent memory in rodents have revealed modulatory factors and physiological mechanisms by which acute stress can enhance long-term memory. However, extending these findings and mechanisms to understand when stress will enhance declarative memory in humans faces important challenges. This review synthesizes human and rodent studies of stress and memory, examining translational gaps related to measurements of declarative memory and stress responses in humans. Human studies diverge from rodent research by assessing declarative memories that may not depend on the hippocampus and by measuring peripheral rather than central stress responses. This highlights opportunities for future research across species, including assessing stress effects on hippocampal-dependent memory processes in humans and relating peripheral stress responses to stress effects on the function of memory-related brain regions in rodents. Together, these investigations will facilitate the translation of stress effects on memory function from rodents to humans and inform interventions that can harness the positive effects of stress on long-term memory.

Transcutaneous vagus nerve stimulation (tVNS) enhances conflict-triggered adjustment of cognitive control

Response conflicts play a prominent role in the flexible adaptation of behavior as they represent context-signals that indicate the necessity for the recruitment of cognitive control. Previous studies have highlighted the functional roles of the affectively aversive and arousing quality of the conflict signal in triggering the adaptation process. To further test this potential link with arousal, participants performed a response conflict task in two separate sessions with either transcutaneous vagus nerve stimulation (tVNS), which is assumed to activate the locus coeruleus-noradrenaline (LC-NE) system, or with neutral sham stimulation. In both sessions the N2 and P3 event-related potentials (ERP) were assessed. In line with previous findings, conflict interference, the N2 and P3 amplitude were reduced after conflict. Most importantly, this adaptation to conflict was enhanced under tVNS compared to sham stimulation for conflict interference and the N2 amplitude. No effect of tVNS on the P3 component was found. These findings suggest that tVNS increases behavioral and electrophysiological markers of adaptation to conflict. Results are discussed in the context of the potentially underlying LC-NE and other neuromodulatory (e.g., GABA) systems. The present findings add important pieces to the understanding of the neurophysiological mechanisms of conflict-triggered adjustment of cognitive control.

Time course of the physiological stress response to an acute stressor and its associations with the primacy and recency effect of the serial position curve

Whether stress affects memory depends on which stress pathway becomes activated and which specific memory system is involved. The activation of the sympathetic nervous system (SNS), leads to a release of catecholamines. The activation of the hypothalamic-pituitary-adrenal (HPA) axis, leads to a release of glucocorticoids. In thus study, it was investigated whether SNS and/or HPA axis activation are associated with long-term memory (LTM) and/or working memory (WM) performance in humans. Thirty-three participants underwent the socially evaluated cold-pressor test. Salivary alpha-amylase (sAA) was used as a marker for the activation of the SNS and cortisol as marker for HPA axis activation. Memory was assessed by means of word lists with 15 words each. The primacy effect (i.e., the correctly recalled words from the beginning of the lists) of the serial position curve was considered as indicator for LTM. The recency effect (i.e., the correctly recalled words from the end of the lists) were used as estimator for WM performance. In sAA responders, the recency effect and, therefore, WM performance increased immediately after the stressor. This was not found in sAA non-responders. In cortisol responders, the primacy effect and, thus, LTM performance decreased 20 minutes after the stressor. No change in LTM performance was found in cortisol non-responders. Our study supports the assumptions that 1) SNS activation is associated with WM processes via stimulation of the prefrontal cortex, and 2) HPA axis activation is associated with LTM processes through interactions with the hippocampus.

A single bout of hard RPE-based cycling exercise increases salivary alpha-amylase

Exercise exerts beneficial effects on cognition, in part by stimulating an arousal response that includes the release of catecholamines. Sympathetic nervous system arousal and activation of the noradrenergic system in particular may enhance cognitive performance. Measurement of salivary alpha-amylase, a non-invasive biomarker of central noradrenergic activity, is a promising avenue for characterizing the arousal-mediated effects of exercise on cognition. However, the effectiveness of high-intensity acute exercise, and the time course of sAA concentrations following exercise, has not been clearly described. The purpose of this study was to determine the effects of 20 min of perceived exertion-based high-intensity cycling exercise on salivary alpha-amylase levels in healthy young adults. We utilized a repeated-measures design to examine the sAA response to cycling exercise, rest, and an emotional picture viewing task. Thirty-two participants between the ages of 18-30 viewed pleasant, neutral, and unpleasant pictures from the International Affective Picture System. Before and after the task, participants completed either 20 min of seated rest or cycling exercise at an intensity corresponding to 15 ("hard") on Borg's Ratings of Perceived Exertion scale. Salivary alpha-amylase was assessed at time points immediately before and after rest, exercise, and the picture viewing task. Exercise elicited a robust increase in salivary alpha-amylase approximately six times higher than that induced by emotional picture viewing. Importantly, the observed exercise-induced increase in salivary alpha-amylase returned to a level comparable to baseline after ten minutes. These findings have meaningful implications for future work characterizing the relationship between exercise and arousal-mediated effects on cognitive performance.