Investigating the Association Between Early Life Parental Care and Stress Responsivity in Adulthood

Hippocampus links perceived social support with self-esteem

Self-esteem is an important psychological resource with adaptive values, and numerous investigations have revealed that self-esteem is influenced by perceived social support. However, the potential neural basis linking perceived social support with self-esteem remains unclear. Therefore, we used voxel-based morphometry to explore whether the hippocampus and amygdala function as the neuroanatomical basis linking perceived social support with self-esteem in a cohort of 243 young healthy adults (128 women; mean age 22.64 years, standard deviation 1.01 years). The Social Provisions Scale and Rosenberg Self Esteem Scale were used for the survey. Magnetic resonance imaging was used to measure the gray matter volume of the hippocampus and amygdala. Correlation analysis revealed that those who perceived more social support had higher self-esteem. Notably, mediation analysis showed that hippocampal gray matter volume linked perceived social support with self-esteem. Our study suggests that the hippocampus plays a primary, but not exclusive, role in linking perceived social support with self-esteem, which provides a novel explanation for how perceived social support affects self-esteem from the perspective of cognitive neuroscience.

Childhood experiences of being parented, adult attachment, psychological inflexibility, social engagement, and mental health of autistic adults

BACKGROUND

Autistic adults have an increased risk of poor mental health. Although parental care and overprotection in childhood influence later attachment and mental health in the general adult population, this has not been investigated in the autistic population. Likewise, the roles of psychological inflexibility and social engagement in influencing mental health outcomes for autistic adults have yet to be examined.

AIMS

To examine if retrospectively recalled childhood experiences of parental care and overprotection, as well as current adult attachment, psychological inflexibility and social engagement are associated with mental health in autistic adulthood. Further, to examine mediators of the association between parental care and overprotection and mental health in autistic adults.

METHODS AND PROCEDURES

A community-recruited convenience sample of 126 Australian autistic adults completed an online survey assessing childhood experiences of parental care and overprotection and current adult attachment, psychological inflexibility, social engagement, and mental health.

OUTCOMES AND RESULTS

Linear regressions showed that psychological inflexibility was the strongest predictor of depression, anxiety, and stress, followed by attachment anxiety (depression, anxiety) and attachment avoidance (anxiety, stress). Mediation analyses revealed that psychological inflexibility and attachment anxiety mediated the associations between parental care and overprotection and mental health outcomes in autistic adulthood.

CONCLUSIONS AND IMPLICATIONS

Psychological inflexibility and adult attachment (anxious and avoidant attachment) are important to understanding mental health of autistic adults. Psychological inflexibility and attachment anxiety mediate associations between recalled childhood experiences of parental care and overprotection and mental health in autistic adulthood.

Effects of parental care and overprotection on adolescents' diurnal cortisol profiles

Parental bonding is a strong determinant of children's health. One of the proposed pathways through which parenting impacts children's health is by altering the functioning of stress response systems. The current study aims to investigate the associations between two types of parental bonding (care and overprotection) and functioning of hypothalamic-pituitary-adrenal (HPA) axis (i.e., diurnal cortisol secretion) in a sample of 255 healthy adolescents (46.3% girls; aged 11-14 years). Participants completed the Parental Bonding Instrument and provided eight cortisol samples across two consecutive days to assess patterns of diurnal cortisol secretion. Multilevel modeling and multiple linear regression were utilized to test the main effects and interactive effects of parental care and overprotection on adolescents' wakeup cortisol, cortisol awakening response, cortisol slope, and total cortisol secretion. Results showed that parental care was associated with higher cortisol levels at awakening, while parental overprotection was associated with lower cortisol levels at awakening. Parental overprotection, but not parental care, was associated with flatter cortisol slopes. No interactive effects between parental care and overprotection on cortisol parameters emerged. The current findings add to the existing literature on parenting behavior and HPA functioning by showing that parental care and overprotection differently regulated daily cortisol parameters implicated in health.

Predicting Health-Related Quality of Life in Trauma-Exposed Male Veterans in Late Midlife: A 20 Year Longitudinal Study

Trauma-exposed adults with high levels of posttraumatic stress symptoms (PTSS) report poorer health-related quality of life (HRQOL), but less is known about the persistence of this relationship over time. Participants from the Vietnam Era Twin Study of Aging reported on PTSS, health, and sociodemographic characteristics at average age 38; 775 participants reported having been exposed to trauma. Later, at average ages 56 and 62, mental and physical HRQOL were assessed with the Short-Form 36. Premorbid risk for anxiety/neuroticism was evaluated with a polygenic risk score derived from a large genome-wide association study meta-analysis. In multivariate mixed models, having higher levels of PTSS, poorer self-rated health, lower income, and less education at age 38 were associated with worse physical and mental HRQOL two decades later. Chronic health problems at age 38 predicted midlife physical but not mental HRQOL. Although genetic risk for neuroticism was correlated with HRQOL and PTSS, it was no longer significant in multivariate models. Health-related quality of life (HRQOL) predicts morbidity and mortality independently of objective health measures; early interventions may help to mitigate the ongoing impact of trauma on quality of life.

A review of associations between parental emotion socialization behaviors and the neural substrates of emotional reactivity and regulation in youth

As highlighted by Eisenberg, Cumberland, and Spinrad (1998), parents play a critical role in children's socioemotional development, in part, by shaping how children and adolescents process, respond to, and regulate their emotions (i.e., emotional reactivity/regulation). Although evidence for associations between parenting behavior and youth's emotional processing has relied primarily on behavioral measures of emotion, researchers have begun to examine how parenting is related to the neural substrates of youth's reactivity and regulation. This article reviews a growing literature linking parental behavior with structural brain development as well as functional activity and connectivity in neural regions supporting emotional reactivity/regulation during infancy, childhood, and adolescence. By focusing on normative parental behaviors, we evaluate the evidence for associations between typical variations in caregiving and neural processes thought to support youth's emotional reactivity/regulation. The purpose of this review is to (1) extend the model put forth by Eisenberg and colleagues to consider the ways that parenting behaviors are related to neural substrates of youth's emotional reactivity and regulation; (2) review the empirical evidence for associations between parenting, particularly parental "emotion-related socialization behaviors" (ERSBs), and neural substrates of youth's emotional reactivity/regulation; and (3) recommend future directions for this emerging area of research. (PsycINFO Database Record (c) 2020 APA, all rights reserved).

Neurobiological mechanisms underlying sex-related differences in stress-related disorders: Effects of neuroactive steroids on the hippocampus

Men and women differ in their vulnerability to a variety of stress-related illnesses, but the underlying neurobiological mechanisms are not well understood. This is likely due to a comparative dearth of neurobiological studies that assess male and female rodents at the same time, while human neuroimaging studies often don't model sex as a variable of interest. These sex differences are often attributed to the actions of sex hormones, i.e. estrogens, progestogens and androgens. In this review, we summarize the results on sex hormone actions in the hippocampus and seek to bridge the gap between animal models and findings in humans. However, while effects of sex hormones on the hippocampus are largely consistent in animals and humans, methodological differences challenge the comparability of animal and human studies on stress effects. We summarise our current understanding of the neurobiological mechanisms that underlie sex-related differences in behavior and discuss implications for stress-related illnesses.

Perceived maternal care is associated with emotional eating in young adults

INTRODUCTION

Early life adversity, including the perception of poor quality of maternal care, is associated with long-term metabolic and psychosocial consequences. The negative quality of mother/child relationship is associated with emotional overeating in young children, which is defined by eating in response to emotional arousal states such as fear, anger or anxiety. However, it is not known if this association persists through adolescence. Therefore, we aimed at verifying if maternal care during infancy can influence emotional eating in young adults.

METHODS

Seventy-five adolescents, residents of Porto Alegre, who participated in the PROTAIA Program (anxiety disorder in childhood and adolescence program), answered the Parental Bonding Instrument (PBI - assessment of perceived maternal care), and the Dutch Eating Behavior Questionnaire (DEBQ). Regression analysis models were built to predict Emotional Eating, a domain of the DEBQ, using maternal care, gender, and anxiety as independent variables.

RESULTS

The model was statistically significant when adjusted for potential confounders (r² = 0.272; p < 0.0001). Emotional eating was significantly predicted by levels of maternal care, anxiety and gender (beta = -0.316; p = 0.006).

CONCLUSION

The results demonstrated a negative association between the quality of maternal care and emotional eating in young adults, suggesting that the early environment could be involved on the development of eating disorders or on the differential eating behavior in adolescents with emotional disorders.

The brain's hemodynamic response function rapidly changes under acute psychosocial stress in association with genetic and endocrine stress response markers

Ample evidence links dysregulation of the stress response to the risk for psychiatric disorders. However, we lack an integrated understanding of mechanisms that are adaptive during the acute stress response but potentially pathogenic when dysregulated. One mechanistic link emerging from rodent studies is the interaction between stress effectors and neurovascular coupling, a process that adjusts cerebral blood flow according to local metabolic demands. Here, using task-related fMRI, we show that acute psychosocial stress rapidly impacts the peak latency of the hemodynamic response function (HRF-PL) in temporal, insular, and prefrontal regions in two independent cohorts of healthy humans. These latency effects occurred in the absence of amplitude effects and were moderated by regulatory genetic variants of KCNJ2, a known mediator of the effect of stress on vascular responsivity. Further, hippocampal HRF-PL correlated with both cortisol response and genetic variants that influence the transcriptional response to stress hormones and are associated with risk for major depression. We conclude that acute stress modulates hemodynamic response properties as part of the physiological stress response and suggest that HRF indices could serve as endophenotype of stress-related disorders.

Rare missense coding variants in oxytocin receptor (OXTR) in schizophrenia cases are associated with early trauma exposure, cognition and emotional processing

BACKGROUND

Oxytocin is a peptide hormone that influences the integration of social cognition with behavior and affect regulation. Oxytocin also prominently directs the transition of neuronal GABA neurotransmission from excitatory to inhibitory after birth. The oxytocin receptor (OXTR) is linked to schizophrenia, a heterogeneous syndrome. Relationships of OXTR polymorphisms with specific clinical features could aid in evaluating any role of oxytocin in the pathogenesis of schizophrenia.

METHOD

Schizophrenia cases with rare missense coding OXTR single nucleotide variants (SNVs) were identified from a well-characterized sample of cases and controls who were assessed for symptoms, cognition and early life trauma.

RESULTS

Five of 48 cases showed rare OXTR variants. Compared to the other cases they had less severe negative symptoms (deficits in emotional expression and motivation) and less severe general psychopathology scores (depression and anxiety). They demonstrated lower nonverbal (performance) than verbal intelligence due to deficient perceptual organization and slow processing speed. They also reported greater early trauma exposure (physical and sexual abuse and emotional trauma).

CONCLUSION

Cases carrying rare OXTR SNVs had less negative and affective symptoms than other cases, but similar psychotic symptoms, along with specific cognitive deficits. The clinical characterization of these cases occurred in association with environmental exposure to early trauma, especially sexual abuse, which may have influenced the expression of schizophrenia in subjects harboring specific SNVs in the OXTR.

Associations between subjective well-being and subcortical brain volumes

To study the underpinnings of individual differences in subjective well-being (SWB), we tested for associations of SWB with subcortical brain volumes in a dataset of 724 twins and siblings. For significant SWB-brain associations we probed for causal pathways using Mendelian Randomization (MR) and estimated genetic and environmental contributions from twin modeling. Another independent measure of genetic correlation was obtained from linkage disequilibrium (LD) score regression on published genome-wide association summary statistics. Our results indicated associations of SWB with hippocampal volumes but not with volumes of the basal ganglia, thalamus, amygdala, or nucleus accumbens. The SWB-hippocampus relations were nonlinear and characterized by lower SWB in subjects with relatively smaller hippocampal volumes compared to subjects with medium and higher hippocampal volumes. MR provided no evidence for an SWB to hippocampal volume or hippocampal volume to SWB pathway. This was in line with twin modeling and LD-score regression results which indicated non-significant genetic correlations. We conclude that low SWB is associated with smaller hippocampal volume, but that genes are not very important in this relationship. Instead other etiological factors, such as exposure to stress and stress hormones, may exert detrimental effects on SWB and the hippocampus to bring about the observed association.

Cord Blood DNA Methylation Biomarkers for Predicting Neurodevelopmental Outcomes

Adverse environmental exposures in pregnancy can significantly alter the development of the fetus resulting in impaired child neurodevelopment. Such exposures can lead to epigenetic alterations like DNA methylation, which may be a marker of poor cognitive, motor and behavioral outcomes in the infant. Here we review studies that have assessed DNA methylation in cord blood following maternal exposures that may impact neurodevelopment of the child. We also highlight some key studies to illustrate the potential for DNA methylation to successfully identify infants at risk for poor outcomes. While the current evidence is limited, in that observations to date are largely correlational, in time and with larger cohorts analyzed and longer term follow-up completed, we may be able to develop epigenetic biomarkers that not only indicate adverse early life exposures but can also be used to identify individuals likely to be at an increased risk of impaired neurodevelopment even in the absence of detailed information regarding prenatal environment.

Maternal sensitivity, infant limbic structure volume and functional connectivity: a preliminary study

Mechanisms underlying the profound parental effects on cognitive, emotional and social development in humans remain poorly understood. Studies with nonhuman models suggest variations in parental care affect the limbic system, influential to learning, autobiography and emotional regulation. In some research, nonoptimal care relates to decreases in neurogenesis, although other work suggests early-postnatal social adversity accelerates the maturation of limbic structures associated with emotional learning. We explored whether maternal sensitivity predicts human limbic system development and functional connectivity patterns in a small sample of human infants. When infants were 6 months of age, 20 mother-infant dyads attended a laboratory-based observational session and the infants underwent neuroimaging at the same age. After considering age at imaging, household income and postnatal maternal anxiety, regression analyses demonstrated significant indirect associations between maternal sensitivity and bilateral hippocampal volume at six months, with the majority of associations between sensitivity and the amygdala demonstrating similar indirect, but not significant results. Moreover, functional analyses revealed direct associations between maternal sensitivity and connectivity between the hippocampus and areas important for emotional regulation and socio-emotional functioning. Sensitivity additionally predicted indirect associations between limbic structures and regions related to autobiographical memory. Our volumetric results are consistent with research indicating accelerated limbic development in response to early social adversity, and in combination with our functional results, if replicated in a larger sample, may suggest that subtle, but important, variations in maternal care influence neuroanatomical trajectories important to future cognitive and emotional functioning.

Social Support Can Buffer against Stress and Shape Brain Activity

Social support from close relationship partners is an important resource for coping with stress, particularly during childhood. We discuss ethical challenges associated with studying stress and its social buffering in the laboratory, as well as emerging evidence regarding two potential neural substrates for the social buffering of stress: hypothalamic oxytocin activity and activation of areas in the prefrontal cortex associated with effective self-regulation. We also address the role of early-life social experiences in shaping brain development, as well as recommendations for practice and policy that would advance the ethical treatment of children and reduce social inequalities in early-life experiences and opportunities-e.g., investing in programs that prevent child maltreatment and facilitating access to high-quality child care for economically disadvantaged families. We also debate the ethical implications of using oxytocin nasal sprays to simulate the stress-reducing properties of social support and advise waiting for more evidence before recommending their use.

Much ado about much: stress, dynamic biomarkers and HPA axis dysregulation along the trajectory to psychosis

OBJECTIVES

In the context of a stress-vulnerability framework, hyperactivation of the hypothalamic-pituitary-adrenal (HPA) axis is thought contribute to the risk, onset and course of psychotic illness. However, recent reports regarding static and dynamic features of the HPA axis suggest a more complex set of phenomena at play in the early phases of psychosis.

METHODS

We review literature regarding structural and functional aspects of the HPA axis in subjects at risk for or experiencing the first episode of psychosis, including evidence favoring as well as that which contradicts a model of HPA axis hyperactivation.

RESULTS

Static measures of diurnal cortisol and hippocampal/pituitary volumes suggest that the HPA axis is in a hyperactivated state in early phases of psychosis. In contrast, the dynamic cortisol response to encountered or anticipated stress is blunted in the same populations. These incongruent findings need to be better understood.

CONCLUSIONS

We consider potential explanations for the seemingly contradictory elevation and blunting of HPA biomarkers in the early course of psychosis. Finally, we propose and explore implications of a conceptual model of tonic HPA hyperactivation and phasic HPA blunting that integrates and reconciles these data.

Childhood maternal care is associated with DNA methylation of the genes for brain-derived neurotrophic factor (BDNF) and oxytocin receptor (OXTR) in peripheral blood cells in adult men and women

In adults, reporting low and high maternal care in childhood, we compared DNA methylation in two stress-associated genes (two target sequences in the oxytocin receptor gene, OXTR; one in the brain-derived neurotrophic factor gene, BDNF) in peripheral whole blood, in a cross-sectional study (University of Basel, Switzerland) during 2007-2008. We recruited 89 participants scoring < 27 (n = 47, 36 women) or > 33 (n = 42, 35 women) on the maternal care subscale of the Parental Bonding Instrument (PBI) at a previous assessment of a larger group (N = 709, range PBI maternal care = 0-36, age range = 19-66 years; median 24 years). 85 participants gave blood for DNA methylation analyses (Sequenom(R) EpiTYPER, San Diego, CA) and cell count (Sysmex PocH-100i™, Kobe, Japan). Mixed model statistical analysis showed greater DNA methylation in the low versus high maternal care group, in the BDNF target sequence [Likelihood-Ratio (1) = 4.47; p = 0.035] and in one OXTR target sequence Likelihood-Ratio (1) = 4.33; p = 0.037], but not the second OXTR target sequence [Likelihood-Ratio (1) < 0.001; p = 0.995). Mediation analyses indicated that differential blood cell count did not explain associations between low maternal care and BDNF (estimate = -0.005, 95% CI = -0.025 to 0.015; p = 0.626) or OXTR DNA methylation (estimate = -0.015, 95% CI = -0.038 to 0.008; p = 0.192). Hence, low maternal care in childhood was associated with greater DNA methylation in an OXTR and a BDNF target sequence in blood cells in adulthood. Although the study has limitations (cross-sectional, a wide age range, only three target sequences in two genes studied, small effects, uncertain relevance of changes in blood cells to gene methylation in brain), the findings may indicate components of the epiphenotype from early life stress.

Stress and the city: impact of urban upbringing on the (re)activity of the hypothalamus-pituitary-adrenal axis

OBJECTIVE

Urbanization is a major challenge for the 21st century with a significant impact on health; mental health, in particular, can be negatively affected. The mechanisms linking urban living to psychopathology, however, remain unclear. We tested the hypothesis that urban upbringing may alter the activity of the hypothalamus-pituitary-adrenal (HPA) axis, one of the body's major stress response systems.

METHODS

In three independent experiments (n = 248 in total), we measured the changes in cortisol, the end-product of the HPA axis, in response to different stress tasks (memory recall with critical social evaluation [Experiment 1] or Socially Evaluated Cold Pressor Test [Experiment 2] and to awakening in participants raised in cities or more rural areas.

RESULTS

Urban upbringing was associated with elevated cortisol responses to acute stress (task × time point of measurement × urbanicity interaction: F(2,132) = 3.10 [p = .048] in Experiment 1 and F(2,112) = 3.29 [p = .041] in Experiment 2) but with a blunted cortisol awakening response (time point of measurement × urbanicity interaction: F(1,114) = 4.00, p = .048). The autonomic stress response, as indicated by blood pressure measurements, was not affected by urban upbringing. Moreover, current city living was not associated with any changes in the physiological responses to stress or awakening.

CONCLUSIONS

Our findings suggest that urban upbringing changes the (re)activity of the HPA axis. Given that changes in HPA axis regulation have been associated with several psychiatric disorders, this may represent a mechanism that contributes to the increased risk for psychopathology in urban populations.

Parental care influences leukocyte telomere length with gender specificity in parents and offsprings

BACKGROUND

There have been several reports suggesting that adverse childhood experiences such as physical maltreatment and long institutionalization influence telomere length. However, there has been no study examining the relationship of telomere length with variations in parental rearing. In the present study, we examined the relationship of leukocyte telomere length with parental rearing in healthy subjects.

METHODS

The subjects were 581 unrelated healthy Japanese subjects. Perceived parental rearing was assessed by the Parental Bonding Instrument consisting of the care and protection factors. Leukocyte relative telomere length was determined by a quantitative real-time PCR method for a ratio of telomere/single copy gene.

RESULTS

In the multiple regression analyses, shorter telomere length in males was related to lower scores of paternal care (β = 0.139, p < 0.05), while that in females was related to lower scores of maternal care (β = 0.195, p < 0.01).

CONCLUSION

The present study suggests that there is linear relationship between parental care and telomere length which covers both lower and higher ends of parental care, and that the effects of parental care on telomere length are gender-specific in parents and offsprings.

Long-term effects of maternal separation on the responsiveness of the circadian system to melatonin in the diurnal nonhuman primate (Macaca mulatta)

Depression is often linked to early-life adversity and circadian disturbances. Here, we assessed the long-term impact of early-life adversity, particularly preweaning mother-infant separation, on the circadian system's responsiveness to a time giver or synchronizer (Zeitgeber). Mother-reared (MR) and peer-reared (PR) rhesus monkeys were subjected to chronic jet-lag, a forced desynchrony protocol of 22 hr T-cycles [11:11 hr light:dark (LD) cycles] to destabilize the central circadian organization. MR and PR monkeys subjected to the T-cycles showed split locomotor activity rhythms with periods of ~22 hr (entrained) and ~24 hr (free-running), simultaneously. Continuous melatonin treatment in the drinking water (20 μg/mL) gradually increased the amplitude of the entrained rhythm at the expense of the free-running rhythm, reaching complete entrainment by 1 wk. Upon release into constant dim light, a rearing effect on anticipation for both the predicted light onset and food presentation was observed. In MR monkeys, melatonin did not affect the amplitude of anticipatory behavior. Interestingly, however, PR macaques showed light onset and food anticipatory activities in response to melatonin treatment. These results demonstrate for the first time a rearing-dependent effect of maternal separation in macaques, imprinting long-term plastic changes on the circadian system well into late adulthood. These effects could be counteracted by the synchronizer molecule melatonin. We conclude that the melatonergic system is targeted by early-life adversity of maternal separation and that melatonin supplementation ameliorates the negative impact of stress on the circadian system.

Psychobiological mechanisms underlying the social buffering of the hypothalamic-pituitary-adrenocortical axis: a review of animal models and human studies across development

Discovering the stress-buffering effects of social relationships has been one of the major findings in psychobiology in the last century. However, an understanding of the underlying neurobiological and psychological mechanisms of this buffering is only beginning to emerge. An important avenue of this research concerns the neurocircuitry that can regulate the activity of the hypothalamic-pituitary-adrenocortical (HPA) axis. The present review is a translational effort aimed at integrating animal models and human studies of the social regulation of the HPA axis from infancy to adulthood, specifically focusing on the process that has been named social buffering. This process has been noted across species and consists of a dampened HPA axis stress response to threat or challenge that occurs with the presence or assistance of a conspecific. We describe aspects of the relevant underlying neurobiology when enough information exists and expose major gaps in our understanding across all domains of the literatures we aimed to integrate. We provide a working conceptual model focused on the role of oxytocinergic systems and prefrontal neural networks as 2 of the putative biological mediators of this process, and propose that the role of early experiences is critical in shaping later social buffering effects. This synthesis points to both general future directions and specific experiments that need to be conducted to build a more comprehensive model of the HPA social buffering effect across the life span that incorporates multiple levels of analysis: neuroendocrine, behavioral, and social.

Adult cognitive ability and socioeconomic status as mediators of the effects of childhood disadvantage on salivary cortisol in aging adults

In this longitudinal study we investigate the influence of childhood disadvantage on midlife hypothalamic-pituitary-adrenal (HPA) axis regulation. Two mechanisms by which early life stress may affect later pathophysiology are through its influence on cognitive functioning or later socioeconomic (SES) disadvantage. We predicted that individual differences in young adult cognitive ability and midlife SES would mediate the influence of childhood disadvantage on midlife cortisol. On each of three nonconsecutive days, participants provided five salivary cortisol samples corresponding to their diurnal rhythm (N=727 men; mean age 55, SD=2.6). We calculated three measures of cortisol regulation (area-under-the curve cortisol reflecting total daytime cortisol output; cortisol-awakening-response; and wake-to-bed slope), averaging scores for each measure across multiple days. Childhood disadvantage combined four dichotomous indicators used previously by Rutter (1985): father low SES; mother education less than 12th grade; major family disruption/separation before age 18; and large family size (more than 5 siblings). The two mediators were a measure of general cognitive ability assessed at age 20 and highest achieved midlife SES. Men from more disadvantaged childhoods were significantly more likely to have dysregulated cortisol at midlife, with higher daytime cortisol levels decades after their childhood experience. Effects of childhood disadvantage were both direct and indirect. Cognitive ability and adult SES, however, only partially mediated the associations between early life stress and midlife cortisol. Specific indirect effects accounted for 33.8% of the total effect of childhood disadvantage [β=0.12 (0.05; 0.18)] on total daytime cortisol. Associations remained significant after accounting for ethnicity, smoking status, and self-reported depressive symptoms.

Psychobiological mechanisms underlying the social buffering of the hypothalamic-pituitary-adrenocortical axis: a review of animal models and human studies across development

Discovering the stress-buffering effects of social relationships has been one of the major findings in psychobiology in the last century. However, an understanding of the underlying neurobiological and psychological mechanisms of this buffering is only beginning to emerge. An important avenue of this research concerns the neurocircuitry that can regulate the activity of the hypothalamic-pituitary-adrenocortical (HPA) axis. The present review is a translational effort aimed at integrating animal models and human studies of the social regulation of the HPA axis from infancy to adulthood, specifically focusing on the process that has been named social buffering. This process has been noted across species and consists of a dampened HPA axis stress response to threat or challenge that occurs with the presence or assistance of a conspecific. We describe aspects of the relevant underlying neurobiology when enough information exists and expose major gaps in our understanding across all domains of the literatures we aimed to integrate. We provide a working conceptual model focused on the role of oxytocinergic systems and prefrontal neural networks as 2 of the putative biological mediators of this process, and propose that the role of early experiences is critical in shaping later social buffering effects. This synthesis points to both general future directions and specific experiments that need to be conducted to build a more comprehensive model of the HPA social buffering effect across the life span that incorporates multiple levels of analysis: neuroendocrine, behavioral, and social.

Blunted cortisol awakening response in men with first episode psychosis: relationship to parental bonding

Early life adversity has been associated with an increased risk for the development of mental health problems, including psychotic disorders, perhaps mediated by a changed regulation of the Hypothalamic Pituitary Adrenal (HPA) axis. Aim of the present study was to confirm our previous finding of an attenuated cortisol awakening response (CAR) in men with first episode psychosis (FEP) and to explore a possible link between a blunted CAR and early adversity as indicated by perceived parental bonding. Fifty-eight patients (38 men, 20 women; mean age 23.25±3.86) with a FEP and 33 healthy community controls (16 men, 17 women; mean age 22.91±3.64) participated in the study. Saliva samples for assessment of the CAR were collected immediately, 30 and 60min after awakening. Complete cortisol samples were available in a reduced sample of 56 patients (37 men) and 30 controls (13 men). Parental bonding during the first 16 years of life was assessed retrospectively with the Parental Bonding Inventory. Results showed a significantly blunted CAR in male compared to female patients, confirming our previously reported findings. We also found a lower CAR in the total FEP group compared to controls, which failed to reach significance after controlling for time of awakening. A significantly lower percentage of patients than controls reported optimal maternal parenting. Within the patient group, significantly fewer male than female patients reported optimal maternal and paternal parenting. Only in patients, unfavorable paternal parenting was related to a blunted CAR. Dysregulation of the HPA axis in male patients might be a consequence of non-optimal parenting and contribute to the less favorable course of psychosis in men compared to women.

Maternal interpersonal affiliation is associated with adolescents' brain structure and reward processing

Considerable animal and human research has been dedicated to the effects of parenting on structural brain development, focusing on hippocampal and prefrontal areas. Conversely, although functional imaging studies suggest that the neural reward circuitry is involved in parental affection, little is known about mothers' interpersonal qualities in relation to their children's brain structure and function. Moreover, gender differences concerning the effect of maternal qualities have rarely been investigated systematically. In 63 adolescents, we assessed structural and functional magnetic resonance imaging as well as interpersonal affiliation in their mothers. This allowed us to associate maternal affiliation with gray matter density and neural responses during different phases of the well-established Monetary Incentive Delay task. Maternal affiliation was positively associated with hippocampal and orbitofrontal gray matter density. Moreover, in the feedback of reward hit as compared with reward miss, an association with caudate activation was found. Although no significant gender effects were observed in these associations, during reward feedback as compared with baseline, maternal affiliation was significantly associated with ventral striatal and caudate activation only in females. Our findings demonstrate that maternal interpersonal affiliation is related to alterations in both the brain structure and reward-related activation in healthy adolescents. Importantly, the pattern is in line with typical findings in depression and post-traumatic stress disorder, suggesting that a lack of maternal affiliation might have a role in the genesis of mental disorders.

The Biology of Caring

Caring, a core tenet of nursing practice, grew out of a holistic approach. Nurse theorists often note the establishment of a therapeutic relationship as the beginning point of caring, with subsequent nursing interventions reliant upon this relationship for effectiveness. Relational exchange serves as a source of either stress or healing between participants, and rarely is its impact neutral. Relational stress, in fact, has become a primary contributor to many disease processes in terms of promotion and progression and perhaps even initiation. Patient–provider relationships have a long history in medical and nursing literature as critical to providing effective interventions, but our understanding of relational dynamics between patients and providers remains fairly superficial. This theoretical article adapts a previously described biobehavioral model to illustrate the nature and centrality of caring relationships in nursing practice. The dynamic process of face-to-face engagement is deconstructed from a psychobiological standpoint in order to understand the physiological, emotional, cognitive, and behavioral impacts of relational interaction. This understanding is then applied to the patient–provider relationship. Finally, the utility of biomarkers of stress, positive emotion and resonance, and of disease is discussed relative to the patient-provider relationship. Methodological and interpretive challenges inherent in this line of research, along with suggestions to address such challenges, are also presented.

A multivariate twin study of hippocampal volume, self-esteem and well-being in middle-aged men

Self-esteem and well-being are important for successful aging, and some evidence suggests that self-esteem and well-being are associated with hippocampal volume, cognition and stress responsivity. Whereas most of this evidence is based on studies on older adults, we investigated self-esteem, well-being and hippocampal volume in 474 male middle-aged twins. Self-esteem was significantly positively correlated with hippocampal volume (0.09, P = 0.03 for left hippocampus, 0.10, P = 0.04 for right). Correlations for well-being were not significant (Ps > 0.05). There were strong phenotypic correlations between self-esteem and well-being (0.72, P < 0.001) and between left and right hippocampal volume (0.72, P < 0.001). In multivariate genetic analyses, a two-factor additive genetic and unique environmental (AE) model with well-being and self-esteem on one factor and left and right hippocampal volumes on the other factor fits the data better than Cholesky, independent pathway or common pathway models. The correlation between the two genetic factors was 0.12 (P = 0.03); the correlation between the environmental factors was 0.09 (P > 0.05). Our results indicate that largely different genetic and environmental factors underlie self-esteem and well-being on one hand and hippocampal volume on the other.

Associations among parenting experiences during childhood and adolescence, hypothalamus-pituitary-adrenal axis hypoactivity, and hippocampal gray matter volume reduction in young adults

Recent human studies have indicated that adverse parenting experiences during childhood and adolescence are associated with adulthood hypothalamus-pituitary-adrenal (HPA) axis hypoactivity. Chronic HPA axis hypoactivity inhibits hippocampal gray matter (GM) development, as shown by animal studies. However, associations among adverse parenting experiences during childhood and adolescence, HPA axis activity, and brain development, particularly hippocampal development, are insufficiently investigated in humans. In this voxel-based structural magnetic resonance imaging study, using a cross-sectional design, we examined the associations among the scores of parental bonding instrument (PBI; a self-report scale to rate the attitudes of parents during the first 16 years), cortisol response determined by the dexamethasone/corticotropin-releasing hormone test, and regional or total hippocampal GM volume in forty healthy young adults with the following features: aged between 18 and 35 years, no cortisol hypersecretion in response to the dexamethasone test, no history of traumatic events, or no past or current conditions of significant medical illness or neuropsychiatric disorders. As a result, parental overprotection scores significantly negatively correlated with cortisol response. Additionally, a significant positive association was found between cortisol response and total or regional hippocampal GM volume. No significant association was observed between PBI scores and total or regional hippocampal GM volume. In conclusion, statistical associations were found between parental overprotection during childhood and adolescence and adulthood HPA axis hypoactivity, and between HPA axis hypoactivity and hippocampal GM volume reduction in healthy young adults, but no significant relationship was observed between any PBI scores and adulthood hippocampal GM volume.

Increased cortisol awakening response and afternoon/evening cortisol output in healthy young adults with low early life parental care

RATIONALE

Growing evidence from animal and human studies suggests a profound and long-lasting influence of early life experiences--ranging from variations in parenting behavior to severe adversity--on hypothalamic-pituitary-adrenal axis function.

OBJECTIVES

The aim of the current investigation was to examine the association between naturally occurring variations in early life parental care and the cortisol awakening response (CAR), afternoon/evening cortisol output and key psychological variables in a sample of healthy young adults.

METHODS

Fifty-eight (19 male and 39 female) participants between 18 and 30 years of age completed psychological questionnaires and collected saliva at awakening, 30 min thereafter and at 3 p.m., 6 p.m., and 9 p.m. on three non-consecutive weekdays.

RESULTS

Participants with low (compared to high) parental care experiences exhibited an increased CAR, increased afternoon/evening cortisol output, decreased self-esteem, and increased depressive symptomatology and anxiety.

CONCLUSIONS

We suggest that the elevated CAR and afternoon/evening cortisol levels might reflect a biological correlate of adversity-induced vulnerability for psychopathology. This study is first to show an association between the retrospective perception of early life parental care and cortisol circadian rhythms in healthy young adults.

Perceived early-life maternal care and the cortisol response to repeated psychosocial stress

BACKGROUND

In the past decade, a body of animal and human research has revealed a profound influence of early-life experiences, ranging from variations in parenting behaviour to severe adversity, on hypothalamic-pituitary-adrenal axis regulation in adulthood. In our own previous studies, we have shown how variations in early-life parental care influence the development of the hippocampus and modify the cortisol awakening response.

METHODS

In the present study, we investigated the influence of early-life maternal care on cortisol, heart rate and subjective psychological responses to the repeated administration of a psychosocial laboratory stressor in a population of 63 healthy young adults. Low, medium and high early-life maternal care groups were identified using the Parental Bonding Instrument.

RESULTS

Controlling for the effect of sex, we found an inverted u-shaped relation between increasing levels of maternal care and cortisol stress responsivity. Specifically, overall and stress-induced cortisol levels went from below normal in the low maternal care, to normal in the medium care, back to below normal in the high maternal care groups. We found no group differences with respect to heart rate and subjective psychological stress measures. Whereas low and high maternal care groups exhibited similarly low endocrine stress responses, their psychological profiles were opposed with increased levels of depression and anxiety and decreased self-esteem in the low care group.

LIMITATIONS

Sex was unequally distributed among maternal care groups, whereby the number of men with low maternal care was too small to allow introducing sex as a second between-group variable.

CONCLUSION

We discuss the potential significance of this dissociation between endocrine and psychological parameters with respect to stress vulnerability and resistance for each maternal care group.