Lactation and stress: protective effects of breast-feeding in humans

Whilst most research on breast-feeding has been designed to assess its importance for infant health or to find a human nutrient replacement for infant formula, the effects of breast-feeding on maternal health have received little scientific attention. In several animal studies lactation has been shown to be associated with a marked blunting of physiological and behavioral responses to physical and psychological stress. However, the literature on the effects of lactation on stress in humans remains limited. This review focuses primarily on recent findings on the effects of breast-feeding on neuroendocrine and behavioral responses to acute stress exposure in lactating women. The available data suggest that breast-feeding suppresses the hypothalamic-pituitary-adrenal (HPA) axis response to physical and psychosocial stress. However, lactation in women, in contrast to lactating rats, does not seem to result in a general restraint of the endocrine stress response during the whole period of lactation. Recent data strongly suggest that the blunted HPA axis response to stress in women seems to be counterbalanced if the acute stressor, at least when of a psychosocial nature, occurs later than 1 h after suckling. Further elucidation of the underlying psychobiological mechanisms involved in suppressed stress responses during lactation will no doubt lead to new insights into improved health sequelae of breast-feeding in women and to a better understanding of the psychobiology of human stress protection in general.     

Lifetime stress exposure and health: A review of contemporary assessment methods and biological mechanisms

Life stress is a central construct in health research because it is associated with increased risk for a variety of serious mental and physical health problems, including anxiety disorders, depression, cardiovascular disease, autoimmune disorders, Alzheimer's disease, certain cancers, and other diseases of aging. In this review, we examine how lifetime stress exposure contributes to elevated disease risk and explore ongoing measurement and scientific issues related to this topic. To accomplish these goals, we first review existing instruments that have been developed for assessing perceived stress, self‐reported life events, interviewer‐assessed life stressors, and lifetime stress exposure. Next, we describe laboratory‐based tasks that have been used for characterizing individual differences in psychological and biological stress reactivity. These methods have yielded an enormous amount of data showing how life stress influences the activity of the hypothalamic–pituitary–adrenal axis, hypothalamic–pituitary–gonadal axis, sympathetic–adrenal–medullary axis, and immune system, and how such processes can in turn cause allostatic load and biological embedding of the stress effect at the level of the human brain and genome. At the same time, many critical measurement and scientific issues remain unresolved, and we discuss these topics last while describing some pressing issues and opportunities for future research on stress and health.     

Challenge-control interaction as reflected in sympathetic-adrenal and pituitary-adrenal activity: comparison between the sexes

The relative sensitivity of the sympathetic-adrenal and pituitary-adrenal systems to different psychosocial demands is considered on the basis of experimental data. It is concluded that positive and negative aspects of psychological arousal ("effort" and "distress") are differentially associated with the activity of each of the two systems, effort being related primarily to catecholamine secretion, distress primarily to cortisol secretion. Data are presented to illustrate the role of personal control as a major modulating factor. Controllability tends to reduce the negative aspects and enhance the positive aspects of arousal, thereby changing the balance between sympathetic-adrenal and pituitary-adrenal activity. The neuroendocrine pattern is the same for males and females, but there is a consistent sex difference in that females are less prone than males to respond to achievement demands by increased catecholamine secretion. The relative influence of biological and social factors on this sex difference in reactivity is discussed.     

皮质醇日常节律与儿童问题行为及心理社会因素的关系

HPA轴(下丘脑?垂体?肾上腺皮质轴, hypothalamic-pituitary-adrenal cortex axis)是人体应对压力的重要神经内分泌系统, 其终产物皮质醇常作为测量压力的生物学指标。目前的研究多通过皮质醇日常节律表示静息状态下HPA轴的活动, 而日常节律因其较高的稳定性和可靠性成为儿童生理健康评估的最佳指标。儿童期迅速发育的神经内分泌系统与儿童的行为相互作用, 并受到多种心理社会因素的影响。以往研究主要关注皮质醇日常节律与儿童问题行为及心理社会因素的关系, 未来研究应讨论逆境条件下影响儿童成长的危险性因素和保护性因素, 并探索环境对儿童行为影响可能存在的内分泌机制。     

Persistent neuroendocrine changes in multiple hormonal axes after a single or repeated stressor exposures

Many researchers have studied acute responses to stress in animals and how they are modified by prior stressor exposure, but relatively few have examined whether responses to stressors might last for prolonged periods of time. We have previously demonstrated that trough plasma corticosterone levels in rats are elevated for three to five days after single or repeated exposures to mild restraint and inescapable tailshock. The current study measured other aspects of the adrenal axis, and activity in other neuroendocrine systems, 24 hours after one or three consecutive exposures to the same stress paradigm. The data indicated persistent activation of the adrenal axis and prolactin levels, whereas the thyroid and reproductive hormone axes were inhibited after either one or three stress sessions. These changes are remarkable in that one would have expected acute responses to even intense stressors to have ended within hours after the end of the stressor. It will be important to understand the interactions among these responding neuroendocrine systems and to know how long such persistent changes last. Finally, it will be critical to understand the relative contributions of neuroendocrine and psychological factors in maintaining these persistent neuroendocrine changes after exposure to intense stressors.     

Biological basis of the stress response

Chronic, as well as acute emotional arousal, is a consequence of various types of social interaction, i.e., those between mother and infant and between controlling dominant and less effective subordinate. The neurohumoral accompaniments of this social stress include the sympathetic adrenal medullary and hypothalamic pituitary adrenal responses. A common ensuing pathophysiological state involves a chronic increase of blood pressure. Although Selye’s General Adaptation Syndrome presupposed the same response to a variety of stimuli; recent work shows that specific perceptions of control result in different patterns of neuroendocrine activation. A challenge perceived as easy to handle will elicit an active coping response and release of the neurosympathetic system’s norepinephrine. Testosterone will rise as the subject savors success. With increasing anxiety this active coping shifts to a more passive mode and the behavior becomes less assured as the animal loses control. The norepinephrine/epinephrine ratio decreases as epinephrine, prolactin, renin and fatty acids rise. As the outcome becomes still less certain and distress grows, adrenocorticotropic hormone and cortisol levels arise. Thus, the effort required on the one hand and the degree of frustration conflict and uncertainty on the other, determine the ratio of catecholamines to corticoids. With severe emotional trauma, brain dysfunction may occur. These effects can be lasting, and corticoids paradoxically return to normal as the behavior changes to that of post-traumatic stress disorder. Repression and denial set in and the organism responds with decreased concern of impaired attachment and increased irritability.     

Altruism or psychological escape: Why does empathy promote prosocial behavior?

Why does empathy promote prosocial behavior? Previous research suggests that empathically aroused individuals help those in need, even when physical escape from the need situation is easy, and this evidence has been used to support the claim that empathy evokes an altruistic motive. However, existing research has not addressed the possibility that empathically aroused participants help because ease of physical escape fails to provide adequate psychological escape from awareness of the victim's suffering and the aversive empathic arousal such awareness produces. The two experiments reported here examined this issue by directly manipulating empathic arousal and the perceived ease of psychological escape among potential helpers. In both experiments, higher rates of helping were observed among empathically aroused participants, even under conditions of easy psychological escape. The findings of both experiments suggest that empathy evokes an altruistic motive to reduce the victim's suffering rather than an egoistic aversive‐arousal reduction motive. In addition, the results of Experiment 1 suggest that concern for psychological escape from the suffering of others may constitute an important independent prosocial motive in need of future study. Copyright © 2008 John Wiley & Sons, Ltd.     

音乐能增强我们的免疫力吗——音乐的心理神经免疫学效应研究的新进展

近十年以来,音乐能够给人类带来健康的研究越来越多。其中,音乐对人免疫系统的影响属于较新的范畴。本文以音乐心理神经免疫学的视角,从内分泌反应、免疫反应以及免疫系统三个方面,探讨音乐是怎样增强人体免疫力的。音乐对于人体的生物学影响已经得到了公认,但是音乐的心理神经免疫学还是需要更多的量化证明,关于此方面的进一步的研究可能影响到我们医疗保健的整体模型。     

Acute stress reactions: can biological responses predict posttraumatic stress disorder?

What biological responses characterize those acute trauma reactions that develop into chronic psychiatric disorder? The need to understand the genesis of posttraumatic psychological disorders has resulted in much attention on biological reactions in the initial aftermath of trauma exposure. This review outlines the prevailing biological models of acute stress reaction and critiques the available evidence concerning biological responses to trauma that are associated with subsequent psychological disorder. The roles of peritraumatic dissociation and vulnerability factors for acute stress reaction are also reviewed. The major challenges for research on psychobiological responses to trauma are highlighted.     

人格特质对个体心理性应激反应的调节作用

心理性应激是个体的内稳态受到社会心理威胁时候的状态。面对急性心理性应激源, 有机体的各大机能系统, 包括神经内分泌系统、免疫系统以及自主神经系统等, 会出现一系列生物功能的改变。已有研究表明人格特质(如自尊、特质焦虑和大五人格)会影响个体在心理性应激情境中的反应差异且影响方式尚不统一, 并且不同文化环境下人格特质影响心理性应激反应的方式是不一样的, 然而这种结果的差异有可能是生物标记物的不一致造成的, 也有可能是心理性应激任务的不一致造成的, 不能直接进行比较。未来研究应该在控制这些无关变量的基础上, 从跨文化的角度去考察人格特质对个体心理性应激反应差异的影响。     

Concepts of God and Germs: Social Mechanisms and Cognitive Heuristics

Previous research has shown that the more individuals view observable entities as animate, the more those entities are associated with having psychological and physiological experiences. This study examined the relationship between children's animistic and anthropomorphic reasoning for concepts of unobservable scientific (i.e., germ) and religious (i.e., God) entities. This study further explored how children's conceptions vary according to the social learning opportunities (i.e., discourse, rituals) parents reportedly create. Parent–child dyads with young children from diverse ethnic and religious backgrounds participated. Three central findings emerged. First, children readily associated God with psychobiological characteristics but did not do so to the same extent for germs. Second, children applied more psychobiological properties to both entity types when they believed that the entity was animate. Third, engaging in rituals and discourse with parents was indirectly related to children's concepts of God but not related to their concepts of germs. Overall, this study presented support for a connection between children's animistic and anthropomorphic reasoning for unobservable entities, and an indirect effect of cultural input on this reasoning. The implications of these findings will be discussed.     

Dreading the boards: stress response to a competitive audition characterized by social-evaluative threat

The capacity of psychosocial stressors to provoke the hypothalamic–pituitary–adrenal axis has been demonstrated to vary depending upon a number of psychological factors. Laboratory stressors characterized by social-evaluative threat are proposed to be the most efficacious in the elicitation of a cortisol stress response. Salivary cortisol, cardiovascular, and subjective responses of 16 healthy adults facing a naturalistic stressor characterized by social-evaluative threat (competitive performance auditions) were examined. Audition exposure was sufficient to provoke significant cortisol, arterial blood pressure (systolic and diastolic), and subjective stress responses. Cortisol response reactivity (area under the curve with respect to increase [AUCi]) also correlated with participants' subjective rating of social-evaluative threat. The competitive performance audition context is therefore considered a promising context in which to further explore cortisol responsivity to social-evaluative threat.     

School-aged Children’s Psychobiological Divergence as a Prospective Predictor of Health Risk Behaviors in Adolescence

Recent attachment research suggests that children with avoidant attachment often underreport their psychological distress compared to their physiologic indicators of distress (neuroendocrine reactivity, startle response, event-related potentials). This pattern of behavior (referred to as psychobiological divergence) may confer risk for suboptimal coping behaviors, including substance use, sexual risk-taking, and non-suicidal self-injury (NSSI), because individuals who are not aware of or cannot express their emotional needs may engage in maladaptive strategies to regulate their emotions. In the current pilot study (N?=?45 youth), we investigate whether psychobiological divergence of neuroendocrine and self-reported reactivity in middle childhood prospectively predicts health risk behaviors (HRBs) in adolescence. The results revealed that divergence was significantly associated with adolescents’ substance use and non-suicidal self-injury (NSSI), but not with their sexual behavior. Among adolescents currently reporting low levels of attachment security, divergence was associated with greater self-reported NSSI. Our results provide initial evidence that psychobiological divergence confers risk for substance use and NSSI in combination with current relational distress. We discuss the implications of our findings for adolescent development and clinical risk.     

Child development in the context of adversity: experiential canalization of brain and behavior

The authors examine the effects of poverty-related adversity on child development, drawing upon psychobiological principles of experiential canalization and the biological embedding of experience. They integrate findings from research on stress physiology, neurocognitive function, and self-regulation to consider adaptive processes in response to adversity as an aspect of children's development. Recent research on early caregiving is paired with research in prevention science to provide a reorientation of thinking about the ways in which psychosocial and economic adversity are related to continuity in human development.     

Biological basis of the stress response.

Chronic, as well as acute emotional arousal, is a consequence of various types of social interaction, i.e., those between mother and infant and between controlling dominant and less effective subordinate. The neurohumoral accompaniments of this social stress include the sympathetic adrenal medullary and hypothalamic pituitary adrenal responses. A common ensuing pathophysiological state involves a chronic increase of blood pressure. Although Selye's General Adaptation Syndrome presupposed the same response to a variety of stimuli; recent work shows that specific perceptions of control result in different patterns of neuroendocrine activation. A challenge perceived as easy to handle will elicit an active coping response and release of the neurosympathetic system's norepinephrine. Testosterone will rise as the subject savors success. With increasing anxiety this active coping shifts to a more passive mode and the behavior becomes less assured as the animal loses control. The norepinephrine/epinephrine ratio decreases as epinephrine, prolactin, renin and fatty acids rise. As the outcome becomes still less certain and distress grows, adrenocorticotropic hormone and cortisol levels arise. Thus, the effort required on the one hand and the degree of frustration conflict and uncertainty on the other, determine the ratio of catecholamines to corticoids. With severe emotional trauma, brain dysfunction may occur. These effects can be lasting, and corticoids paradoxically return to normal as the behavior changes to that of post-traumatic stress disorder. Repression and denial set in and the organism responds with decreased concern of impaired attachment and increased irritability.     

Psychobiology of boredom

The study of the psychobiological bases of boredom has been limited by the vagueness of its clinical constructs and the difficulties in applying adequate experimental models. The theoretical background of previous research mainly has been based upon cognitive and behavioral psychology by using neuropsychological constructs, such as arousal, attention, motivation, sensation-seeking, and the reward system. Recently acquired data depict a complex and fragmentary picture. In this article, the author presents a review of the literature as well as some personal considerations on this intriguing topic.     

Effects of acute psychosocial stress exposure on endocrine and affective reactivity in college students differing in the 5-HTTLPR genotype and trait neuroticism

Enhanced stress vulnerability has been implicated in the pathogenesis of affective disorders. Although both genetic (5-HTTLPR) and cognitive (neuroticism) factors are known to increase stress vulnerability, no experimental study has investigated the interaction between these two factors on psychobiological reactivity following acute stress exposure. This study used a balanced experimental design to examine the interaction between the 5-HTTLPR genotype and trait neuroticism in neuroendocrine and affective stress responses. From a large group of 771 students, 48 carriers of the short/short (S/S) allele and 48 carriers of the long/long (L/L) allele with the lowest and the highest neuroticism scores (77 females, 19 males; mean age?±?SD: 20.6?±?2 years) were selected and exposed to an acute psychosocial stressor. Mood was assessed before and after the stressor, and salivary cortisol concentrations were measured before and at 20, 30, and 60?min after stressor onset. Acute stress increased salivary cortisol concentration regardless of either 5-HTTLPR genotype or neuroticism, but it caused a less profound negative mood change in L/L compared to S/S-allele carriers with the lowest neuroticism scores. The 5-HTTLPR genotype influences affective reactivity to acute stress conditional upon neuroticism, improving resilience to acute stress in L/L-allele carriers if they do not already possess high cognitive-affective (neuroticism) vulnerability.     

Cardiovascular and neuroendocrine activity in preschool children: Comparison between day-care and home levels

Thirty boys and 30 girls at nine day-care centers were examined at the mean age of 3.5 and 5.5 with regard to systolic and diastolic blood pressure, heart rate and neuroendocrine activity (urinary catecholamines and cortisol) during a day at their day-care center and in their home, respectively. Compared to home levels, day-care was associated with increased heart rate, epinephrine and norepinephrine excretion and decreased cortisol levels. Systolic blood pressure decreased at the day-care centers at the age of 3.5 and increased at the age of 5.5. No significant sex differences were found. The possible role of mental and physical arousal and the dissociation between the sympathetic-adrenal medullary and the pituitary-adrenal cortical responses are discussed.     

Formal Mentoring in Military Academies

We examined the relationship between mentoring functions and protégé outcomes in formal mentoring relationships in military academies. A total of 424 (listed as 424 under Method) freshmen and 659 senior cadets from six different military academies participated in the survey. Results of hierarchical multiple regression analyses suggest that career mentoring was positively related to mentor satisfaction and participants' provision of career mentoring to their protégés. Surprisingly, career mentoring was negatively related to freshmen's commitment to a military career. We found that psychosocial mentoring was positively related to mentor satisfaction and participants' commitment to a military career, leadership competency, and provision of psychosocial mentoring to their protégés. Furthermore, psychological mentoring was negatively related to stress. We discuss these findings and their implications for mentoring research and practices in the military.     

Salivary Cortisol as a Biomarker in Social Science Research

Cortisol, a neuroendocrine hormone measurable in saliva, responds to internal and external triggers. In providing a peripheral ‘window on the brain’, it has been increasingly incorporated into social psychological studies. Cortisol secretion can be studied in two main ways, examination of acute stress reactivity and examination of the basal circadian patterns. These can inform aspects of acute and chronic stress exposure and relationships with health. Within non‐clinical populations, cortisol effects are largely driven by differences in the perception of threat. For social psychologists, this provides an interesting avenue for the investigation of social factors that mediate perceptions of threat, such as social support, relationship processes, and group dynamics in acute and chronic stress. This paper provides a background to understanding the regulation and function of cortisol, and issues arising in relation to its measurement in saliva. It discusses and makes recommendations on the use of appropriate cortisol measures in the study of both acute and chronic stress. Used and interpreted appropriately, stress reactivity and basal ambulatory measures of salivary cortisol can provide a valuable adjunct to self‐report and observation in social psychological research. © 2013 John Wiley & Sons Ltd