Moderation of physiological stress responses by personality traits and daily hassles: less flexibility of immune system responses

Stress gets into the belly: Early life stress and the gut microbiome

Research has established that stress "gets under the skin," impacting neuroendocrine and neuroimmune pathways to influence risk for physical and mental health outcomes. These effects can be particularly significant for early life stress (ELS), or adverse childhood experiences (ACEs). In this review, we explore whether stress gets "into the belly," that is, whether psychosocial stress affects the gut microbiome. We review animal and human research utilizing a variety of stress paradigms (acute laboratory stressors, chronic stress, stressful life events, perceived stress, ELS, in utero stress) and their impacts on the gut microbiota, with a particular focus on ELS. We also review data on dietary interventions to moderate impact of stress on the gut microbiome. Our review suggests strong evidence that acute laboratory stress, chronic stress, and ELS affect the gut microbiota in rodents, and growing evidence that perceived stress and ELS may impact the gut microbiota in humans. Emerging data also suggests, particularly in rodents, that dietary interventions such as omega-3 fatty acids and pre- and pro-biotics may buffer against the effects of stress on the gut microbiome, but more research is needed. In sum, growing evidence suggests that stress impacts not only the neuroendocrine and neuroimmune axes, but also the microbiota-gut-brain-axis, providing a pathway by which stress may get "into the belly" to influence health risk.

Datasets for Cognitive Load Inference Using Wearable Sensors and Psychological Traits

This study introduces two datasets for multimodal research on cognitive load inference and personality traits. Different to other datasets in Affective Computing, which disregard participants’ personality traits or focus only on emotions, stress, or cognitive load from one specific task, the participants in our experiments performed seven different tasks in total. In the first dataset, 23 participants played a varying difficulty (easy, medium, and hard) game on a smartphone. In the second dataset, 23 participants performed six psychological tasks on a PC, again with varying difficulty. In both experiments, the participants filled personality trait questionnaires and marked their perceived cognitive load using NASA-TLX after each task. Additionally, the participants’ physiological response was recorded using a wrist device measuring heart rate, beat-to-beat intervals, galvanic skin response, skin temperature, and three-axis acceleration. The datasets allow multimodal study of physiological responses of individuals in relation to their personality and cognitive load. Various analyses of relationships between personality traits, subjective cognitive load (i.e., NASA-TLX), and objective cognitive load (i.e., task difficulty) are presented. Additionally, baseline machine learning models for recognizing task difficulty are presented, including a multitask learning (MTL) neural network that outperforms single-task neural network by simultaneously learning from the two datasets. The datasets are publicly available to advance the field of cognitive load inference using commercially available devices.

Individual differences in inflammatory and oxidative mechanisms of stress-related mood disorders

Emotional stress leads to the development of peripheral disorders and is recognized as a modifiable risk factor for psychiatric disorders, particularly depression and anxiety. However, not all individuals develop the negative consequences of emotional stress due to different stress coping strategies and resilience to stressful stimuli. In this review, we discuss individual differences in coping styles and the potential mechanisms that contribute to individual vulnerability to stress, such as parameters of the immune system and oxidative state. Initial differences in inflammatory and oxidative processes determine resistance to stress and stress-related disorders via the alteration of neurotransmitter content in the brain and biological fluids. Differences in coping styles may serve as possible predictors of resistance to stress and stress-related disorders, even before stressful conditions. The investigation of natural variabilities in stress resilience may allow the development of new methods for preventive medicine and the personalized treatment of stress-related conditions.

Effects of Mortality Salience on Physiological Arousal

Making the inevitability of mortality salient makes people more defensive about their self-esteem and worldviews. Theoretical arguments and empirical evidence point to a mediating role of arousal in this defensive process, but evidence from physiological measurement studies is scarce and inconclusive. The present study seeks to draw a comprehensive picture of how physiological arousal develops over time in the mortality salience (MS) paradigm, and whether contemplating one's mortality actually elicits more physiological arousal than reflecting on a death-unrelated aversive control topic. In a between-subjects design, participants were asked two open questions about their mortality or about dental pain. Cardiac, respiratory, and electrodermal indicators of arousal were measured both as participants provided written answers to the questions, and during a series of resting intervals surrounding the questions. A Bayes factor analysis indicated support for the hypothesis that the MS paradigm increases physiological arousal, both while answering the two open-ended questions and afterward. Regarding the MS versus dental pain comparison, the null hypothesis of no difference was supported for most analysis segments and signals. The results indicate that the arousal elicited by MS is not different from that elicited by dental pain salience. This speaks against the idea that worldview defense following MS occurs because MS produces higher physiological arousal. Of course, this finding does not rule the importance of other forms of arousal (i.e., subjective arousal) for MS effects.

Inflammation: A Proposed Intermediary Between Maternal Stress and Offspring Neuropsychiatric Risk

During pregnancy, programming of the fetal central nervous system establishes vulnerabilities for emergence of neuropsychiatric phenotypes later in life. Psychosocial influences during pregnancy, such as stressful life events and chronic stress, correlate with offspring neuropsychiatric disorders and inflammation, respectively. Stress promotes inflammation, but the role of inflammation as a mediator between maternal psychosocial stress and offspring neuropsychiatric outcomes has not been extensively studied in humans. This review summarizes clinical evidence linking specific types of stress to maternal inflammatory load during pregnancy. We propose that inflammation is a mediator in the relationship between psychosocial stress and offspring neuropsychiatric outcomes, potentially influenced by poor maternal glucocorticoid-immune coordination. We present relevant experimental animal research supporting this hypothesis. We conclude that clinical and preclinical research supports the premise that stress-induced maternal immune activation contributes in part to prenatal programming of risk. Programming of risk is likely due to a combination of vulnerabilities, including multiple or repeated inflammatory events; timing of such events; poor maternal regulation of inflammation; genetic vulnerability; and lifestyle contributors.

Effects of coping flexibility on cardiovascular reactivity to task difficulty

OBJECTIVE

Coping flexibility refers to an individual's ability to effectively modify his or her coping behavior to better fit the nature of each stressful situation they encounter. More flexible coping is believed to produce more adaptive psychological functioning and physical health.

METHODS

We examined the relationship between coping flexibility and cardiovascular reactivity (CVR) to psychological stress. Challenging tasks of two difficulty levels were presented to 24 men and 24 women aged 18 to 24years. Heart rate (HR), systolic blood pressure (SBP), and diastolic blood pressure were measured.

RESULTS

Change scores (from baseline to reactivity) for SBP and HR responses in the difficult task were higher than those in the easy task and were negatively correlated with coping flexibility during the difficult task but not the easy one.

CONCLUSIONS

The findings suggest that more flexible coping is associated with reduced CVR to a difficult task.

Physiological correlates of psychopathy, antisocial personality disorder, habitual aggression, and violence

This chapter reviews the existing literature on physiological correlates of psychopathy, antisocial personality disorder, and persistent violence/aggression. Coverage is provided of findings from studies utilizing peripheral, electrocortical, and neuroimaging measures. The review begins with a discussion of how psychopathy and antisocial personality are defined, and how these conditions relate to one another and to violent behavior. A case is made that the relationships psychopathy and ASPD show with violent and aggressive behavior, and similarities and differences in associations of each with physiological measures of various types can be understood in terms of symptomatic features these conditions have in common versus features that distinguish them. Following this, an overview is provided of major lines of evidence emerging from psychophysiological and neuroimaging studies conducted to date on these conditions. The final section of the chapter summarizes what has been learned from these existing studies and discusses implications and directions for future research.

Cortisol response to challenge involving low controllability: the role of control beliefs and age

Cortisol responses are typically more pronounced under low controllability conditions, yet little is known about the role of individual differences. This study examined whether cortisol response to a situation with low controllability differs as a function of preexisting control beliefs and age. We manipulated level of controllability using a driving simulator. Control beliefs were assessed prior to the lab session. Salivary cortisol was measured before and after the driving simulation. Participants were 152 adults aged 22-84 from a Boston area sample. In comparison to the normal controllability condition, those in the low controllability condition reported less perceived control over driving, supporting the effectiveness of the manipulation. In the low controllability condition those with higher control beliefs showed a greater cortisol response than those with low control beliefs. Older adults showed a greater cortisol response than younger adults during the challenge. Implications of acute cortisol responses for performance outcomes are discussed.

Cardiovascular and psychological reactivity and recovery from harassment in a biracial sample of high and low hostile men and women

BACKGROUND

This study emphasizes the importance of studying the emotional, motivational, and cognitive characteristics accompanying and the potential hemodynamic mechanisms underlying cardiovascular reactivity to and recovery from interpersonal conflict.

PURPOSE

The relation of dispositional hostility to cardiovascular reactivity during a frustrating anagram task and post-task recovery was investigated.

METHODS

The sample was composed of 99 healthy participants (age, 18-30 years; 53% women; 51% Caucasian; 49% African American)-half randomly assigned to a harassment condition. High and low hostility groups were created by a median split specific to sex and race subgroup score distributions on the Cook-Medley Hostility Scale. It was hypothesized that hostility would interact with harassment such that harassed, high hostile individuals would display the greatest cardiovascular and emotional reactivity and slowest recovery of the four groups. Participants completed a 10-min baseline, a 6-min anagram task, and a 5-min recovery period with blood pressure, heart rate, pre-ejection period, stroke index, cardiac index, and total peripheral resistance index measured.

RESULTS

Harassed participants displayed significantly greater cardiovascular responses and lower positive affect to the task and slower systolic blood pressure (SBP) recovery than did nonharassed participants. The high hostile group, irrespective of harassment, showed blunted cardiovascular responses during the task and delayed SBP recovery than the low hostile group.

CONCLUSION

Although the predicted interaction between hostility and harassment was not supported in the context of cardiovascular responses, such an interaction was observed in the context of blame attributions, whereby harassed hostile participants were found to blame others for their task performance than the other subgroups.

Allostatic load in an environmental riskscape: the role of stressors and gender

Stressors are theorized to be associated with higher allostatic load (AL), a concept of physiological wear measured as a composite of physical biomarkers. Risk of high AL may vary by gender and may be intensified in places with significant environmental risks, otherwise known as 'environmental riskscapes'. Yet, no study has examined the relationship between stressors, gender, and allostatic load in an environmental riskscape. Using primary data collected in a sample (N=1072) exposed to various environmental and social stressors, we find that long-term residence in Texas City (30 or more years), residential proximity to petrochemical plants, perceived poor neighborhood conditions, and daily hassles are associated with higher allostatic load components. Variation in AL differs by gender and the types of biomarkers examined. Gender moderates the effect of length of residence in Texas City on cardiovascular health risk. We discuss our findings in light of current research on stressors, gender, allostatic load, and double jeopardy within environmental riskscapes.

Psychophysiological correlates of aggression and violence: an integrative review

This paper reviews existing psychophysiological studies of aggression and violent behaviour including research employing autonomic, electrocortical and neuroimaging measures. Robust physiological correlates of persistent aggressive behaviour evident in this literature include low baseline heart rate, enhanced autonomic reactivity to stressful or aversive stimuli, enhanced EEG slow wave activity, reduced P300 brain potential response and indications from structural and functional neuroimaging studies of dysfunction in frontocortical and limbic brain regions that mediate emotional processing and regulation. The findings are interpreted within a conceptual framework that draws on two integrative models in the literature. The first is a recently developed hierarchical model of impulse control (externalizing) problems, in which various disinhibitory syndromes including aggressive and addictive behaviours of different kinds are seen as arising from common as well as distinctive aetiologic factors. This model represents an approach to organizing these various interrelated phenotypes and investigating their common and distinctive aetiologic substrates. The other is a neurobiological model that posits impairments in affective regulatory circuits in the brain as a key mechanism for impulsive aggressive behaviour. This model provides a perspective for integrating findings from studies employing different measures that have implicated varying brain structures and physiological systems in violent and aggressive behaviour.

Female temperament, tumor development and life span: relation to glucocorticoid and tumor necrosis factor alpha levels in rats

Behavioral characteristics closely associated with specific physiological profiles present an important area of research in understanding health disparities. In particular, glucocorticoid overproduction may be an important factor moderating disease progression; natural variance in production of this steroid has been proposed as one mechanism underlying individual differences in health and disease. In the current paper, we examined immune parameters in female rats of two different behavioral types previously shown to have differential glucocorticoid production and life spans. We categorized young female rats according to their behavioral response to novelty (high- or low-locomotion), and compared their glucocorticoid production, adrenal size, thymus size, tumor necrosis factor-alpha (TNF-alpha) production, tumor development and life span. As expected, high-locomotion females produced more glucocorticoids and had larger adrenal glands during young adulthood than did low-locomotion females. High-locomotion females had significantly smaller thymuses and reduced TNF-alpha levels compared to low-locomotion, suggesting altered immune function in young adulthood. Finally, high-locomotion females had shorter life spans than did low-locomotion females, and this was particularly true in females that developed pituitary tumors, but not in those that developed mammary tumors. These results, along with other published findings, suggest that high-locomotion rodent females experience life-long elevations in glucocorticoid responses to novelty, and that these elevated levels may be comparable to chronic stress. This naturally occurring endocrine profile may influence immune responses which in turn could affect disease susceptibility. Variance in immune function across personality types may be partially moderated by natural variance in glucocorticoid production.

Dehydration does not influence cardiovascular reactivity to behavioural stress in young healthy humans

Enhanced hydration increases the human cardiovascular reactivity to mental stress. If reduced water intake has the opposite effect, this would suggest controlling for water deprivation when studying such responses. Blood pressure, heart rate and parasympathetically dominated beat-to-beat heart rate fluctuations were assessed during resting baseline and mental stress. Two challenging cognitive-motor tasks, a 5-Choice Reaction Time Task (CRTT) and a Paced Auditory Serial Addition Task (PASAT), served as mental stress tests. Eight female and eight male volunteers were examined twice, after 24 h of water deprivation and after normal water intake (counterbalanced order, 7-day interval). Water deprivation resulted in moderate dehydration with a mean 2.6% decrease of total body weight. Dehydration did neither affect baseline blood pressure, heart rate, nor blood pressure reactivity to mental stress. However, dehydration slightly (-1.2 bpm) diminished heart rate reactivity to the PASAT (P = 0.03) and increased beat-to-beat heart rate fluctuations in response to the CRTT (P = 0.05). Dehydration intensified CRTT- and PASAT-induced reductions of beat-to-beat heart rate fluctuations in females (gender x dehydration interactions: P = 0.04-0.05). Moderate dehydration induced by water restriction has no effect on blood pressure reactivity to mental stress. The effects on heart rate reactivity are small. However, stress-induced parasympathetic withdrawal may be fortified during dehydration in females, which suggests controlling for water intake when studying such responses.

Imaging brain and immune association accompanying cognitive appraisal of an acute stressor

Acute stress elicits multiple responses in autonomic, endocrine, and immune systems. Cognitive appraisal is believed to be one important modulator of such stress responses. To investigate brain substrates of crosstalks between the homeostasis-maintaining systems accompanying appraisal of stressor controllability, we simultaneously recorded regional cerebral blood flow (rCBF) using 15O-water positron emission tomography, cardiovascular indices (heart rate (HR) and blood pressure (BP)), neuroendocrine indices (concentrations of epinephrine, norepinephrine, and adrenocorticotropic hormone (ACTH) in blood), and immune indices (proportions of subsets of lymphocytes (NK cells, helper T cells, cytotoxic T cells, and B cells) in blood), in 11 male subjects who performed a mental arithmetic task with either high controllability (HC) and low controllability (LC). The LC task resulted in less sense of control in subjects than the HC task. Significant increases of rCBF in the medial and lateral orbitofrontal cortices (OFC), and in the medial and lateral prefrontal cortices (MPFC, LPFC) were observed by subtracting the HC task from the LC task. More importantly, significant positive correlations between rCBF and HR, BP, and NK cells were commonly found in the OFC and MPFC during the LC tasks, but not during the HC tasks. The present results showed for the first time that the prefrontal neural network including the OFC and MPFC might be one pivotal region for bi-directional functional association between the brain and peripheral autonomic and immune activities accompanying appraisal of an acute stressor.

Association between plasma inflammatory markers and irrational beliefs; the ATTICA epidemiological study

OBJECTIVE

Recent research data suggest that inflammation and/or depression are associated with the development and progression of cardiovascular disease (CVD). Considering that depression may arise as a response to irrational beliefs according to the Ellis model of psychological disturbances and therapy, we sought to evaluate whether irrational beliefs are associated with plasma inflammatory factors in cardiovascular disease-free people.

METHOD

From May 2001 to December 2002 we randomly enrolled 453 men (23-69 years old) and 400 women (24-71 years old) stratified by age and gender. C-reactive protein, interleukin-6, serum amyloid-A, tumor necrosis factor-alpha and white blood cells were measured in all participants. Detailed dietary characteristics of these people were assessed through a validated food frequency questionnaire. Subjects completed also the irrational beliefs inventory (IBI), which is a brief self-report measure consistent with the Ellis model of psychological disturbance and therapy and the Zung's Depression questionnaire.

RESULTS

The IBI scores were similar in men and women (53+/-11 vs. 53+/-10, p = 0.83). IBI score was positively correlated with C-reactive protein (rho = 0.14, p = 0. 02), interleukin-6 (rho = 0.11, p = 0.02), tumor necrosis factor-alpha (rho = 0.21, p = 0.014) and white blood cell counts (rho = 0.14, p = 0.02). These associations were confirmed even after adjusting for age, sex, years of school, body mass index, physical activity status, depression level and food items consumed by the participants.

CONCLUSION

These findings indicate that irrational beliefs are associated with increased inflammation process, among apparently healthy individuals.

Examination stress as an ecological inducer of cortisol and psychological responses to stress in undergraduate students

The purpose of the present study was to investigate basic methodological issues related to the usage of an examination stress protocol in studies of psychoneuroendocrinology. In the present study, 57 undergraduate students served as participants. All subjects provided salivary samples and completed psychological inventories during a low examination stress period and again during a high examination stress period. Salivary samples were analyzed for cortisol. Three major findings were observed. First, the examination stress protocol proved to be an effective trigger of elevations in both psychological measures of stress and in cortisol levels. Second, sex differences were observed in cortisol levels, such that males showed an elevation in cortisol during the high examination stress session whereas females did not. Finally, no significant correlations were observed between elevations in psychological measures of stress and elevations in cortisol levels. These findings suggest that the examination stress protocol used in the present study effectively elevated both psychological stress and cortisol levels. Furthermore, these findings suggest that there are biological differences in how males and females respond to stress. Finally, no evidence was found to suggest a relationship between psychological and hormonal levels of stress. Together, these findings suggest the need to better define and consider the implications of both the specific measures of stress being used and individual differences in the subject samples in psychoendocrine studies.

Immune, endocrine and cardiovascular responses to controllable and uncontrollable acute stress

This study, using a triadic-yoked design, clarified the effects of controllability of acute stress on responses of immune, cardiovascular (heart rate and blood pressure), and cortisol activities. Forty-three women in their follicular phase completed a mental arithmetic task as a stressor in which controllability was manipulated by correct or yoked-bogus feedback. The task decreased proportions of CD3+ T cells, CD4+ T cells, and CD19+ B cells, whereas it increased the numbers of white blood cells, lymphocytes, natural killer (NK) cells, and NK cell activity (NKCA). Our main hypothesis that greater immune and cardiovascular responses to the task would be obtained under the uncontrollable condition than under the controllable condition was not supported. However, the uncontrollable stress condition, but not the controllable situation, led to higher correlations between heart rate or blood pressure, and various immune parameters. On the other hand, parameters of heart rate variability reflecting sympathetic and parasympathetic activities showed significant correlations only with NKCA. These results suggest that immune responses were most directly associated with cardiovascular activities under the uncontrollable condition.

Stress, social support, emotional regulation, and exacerbation of diffuse plaque psoriasis

The authors' aim was to investigate the role of stressful events, perceived social support, attachment security, and alexithymia in triggering exacerbations of diffuse plaque psoriasis. Inpatients experiencing a recent exacerbation of diffuse plaque psoriasis (N=33) were compared with inpatients with skin conditions believed to have a negligible psychosomatic component (N=73). Stressful events during the last year were assessed with Paykel's Interview for Recent Life Events. Attachment style, alexithymia, and perceived social support were assessed with the Experiences in Close Relationships questionnaire, the Toronto Alexithymia Scale, and the Multidimensional Scale of Perceived Social Support, respectively. Multiple logistic regression analysis was used to control for age, gender, education, marital status, and alcohol consumption. In relation to comparison subjects, the patients with psoriasis had lower perceived social support and higher attachment-related avoidance. Also, they were more likely to have high alexithymic characteristics. There were no differences between the patients with psoriasis and the comparison subjects in scores on the Experiences in Close Relationships anxiety scale, the total number of stressful events, and the number of undesirable, uncontrollable, or major events. Although caution should be applied in generalizing these findings to outpatients, this study suggests that alexithymia, attachment-related avoidance, and poor social support might increase susceptibility to exacerbations of diffuse plaque psoriasis, possibly through impaired emotional regulation. Several physiological mechanisms involving the neuroendocrine and the immune system might mediate the interplay between stress, personality, and diffuse plaque psoriasis.

Effects of appraisal and coping on the neuroendocrine response to extreme stress

Although many people are exposed to extreme stress, only some of them develop psychobiological disturbances that can lead to posttraumatic stress disorder (PTSD) or other posttrauma psychopathology. This paper examines the effects of different types of appraisal and coping to find clues to how individuals differ in their neuroendocrine responses to extreme stress. It proposes a conceptual model for components of the adult response to stressors. Threat appraisal and defensive coping may play crucial roles in determining the neuroendocrine response to trauma with potential mental health consequences, particularly PTSD.