MATERNAL DEPRESSION AND CHILD OXYTOCIN RESPONSE; MODERATION BY MATERNAL OXYTOCIN AND RELATIONAL BEHAVIOR

Breast milk oxytocin and s-IgA modulate infant biomarkers and social engagement; The role of maternal anxiety

Breastfeeding has long been known to improve infants' health and mental development and to enhance the mother-infant bond, but much less research focused on the biological composition of breast milk and its associations with the infant's biomarkers and social development. In this exploratory study, we measured oxytocin (OT) and secretory immunoglobulin-A (s-IgA), the most abundant antibody in breast milk, and evaluated their associations with the same biomarkers in infant saliva and, consequently, with infant social engagement behavior. Fifty-five mother-infant dyads were home-visit and OT and s-IgA were assessed from breast milk and from infant saliva before and after a free-play interaction. Infant social behavior was coded offline using the Coding Interactive Behavior (CIB) and maternal anxiety self-reported. A path model revealed that mother's breast milk s-IgA impacted child social engagement via its links with child OT. In parallel, maternal breast milk OT was linked with infant social behavior through its association with the infant's immunity. This path was moderated by maternal anxiety; only in cases of high anxiety breast milk OT was positively connected to infant s-IgA. Our study, the first to measure OT and s-IgA in both breast milk and infant saliva in relation to observed social behavior, underscores the need for much further research on the dynamic interplay between breast milk composition, infant biomarkers, maternal mental health, and infant social outcomes. Results may suggest that biological systems in breast milk integrate to prepare infants to function in their social ecology through bio-behavioral feedback loops that signal the degree of stress in the environment.

The Impact of Postpartum Depression on the Early Mother-Infant Relationship during the COVID-19 Pandemic: Perception versus Reality

Postpartum depression (PPD) can interfere with the establishment of affective bonds between infant and mother, which is important for the cognitive, social-emotional, and physical development of the child. Rates of PPD have increased during the COVID-19 pandemic, likely due to the added stress and limited support available to new parents. The present study examined whether parenting-related stress, perceived bonding impairments, the quality of observed mother-infant interactions, and salivary oxytocin levels differ between depressed and non-depressed mothers, along with differential impacts of COVID-19 on depressed mothers. Participants included 70 mothers (45 depressed, 25 controls) with infants aged 2-6 months. All data were collected remotely to ease participant burden during the pandemic. Depression was associated with experiences of heightened parenting-related stress and bonding difficulties. These differences were not observed during mother-infant interactions or in salivary oxytocin levels. Differences in COVID-19-related experiences were minimal, though depressed mothers rated slightly higher stress associated with returning to work and financial impacts of the pandemic. Findings highlight the importance of early intervention for PPD to mitigate long-term effects on mothers, children, and families. Additionally, they underscore the need for early intervention to support the developing mother-infant dyad relationship during this crucial time.

Human sweat contains oxytocin

BACKGROUND

Oxytocin (OT) has been detected in various body fluids, including blood, urine, saliva, breastmilk, and spinal fluid. Consistent with models that regard skin as a social organ and in line with studies demonstrating that skin cells express both OT and its receptor, our study sought to examine the presence of OT in human sweat.

METHODS

Overall, 553 individuals participated in a pilot study and three experiments. Firstly, 50 participants provided sweat after engaging in various sports for different durations. Secondly, 26 participants provided sweat from forehead, upper-chest, forearm, and underarm, including 11 in natural setting and 15 following OT administration and a 30-minute exercise. Thirdly, of 435 volunteers, 97 provided sufficient axillary sweat for assaying. Of these, 84 participated in a naturalistic experiment that involved saliva and sweat collection in response to physical activity in either solitary or social settings. OT and testosterone (TS) were assayed in sweat and saliva.

RESULTS

Intense activity for at least 25 min was required to produce sufficient sweat for OT analysis. Highest OT levels were found in axillary sweat compared to sweat from the forehead, upper-chest, and forearm. Salivary OT and TS increased after both solitary and social physical activity; however, higher sweat OT was found after solitary sports. Post-hoc preliminary findings indicate that highly extroverted individuals exercising in solitary environments showed the highest sweat OT levels.

CONCLUSIONS

Findings demonstrate, for the first time, the presence of OT in human sweat and show the feasibility of its measurement. Much further research is required to illuminate how sweat OT is impacted by personality and social context and to uncover the role of the skin in OT production.

Influence of oxytocin on parenting behaviors and parent-child bonding: A systematic review

Oxytocin (OT) plays a pivotal role in early parent-child relationship formation and bonding that is critical for the social, cognitive, and emotional development of the child. Therefore, this systematic review aims to consolidate all available evidence regarding the associations of parental OT concentration levels with parenting behavior and bonding within the past 20 years. A systematic search was conducted in five databases from 2002 to May 2022, and 33 studies were finalized and included. Due to the heterogeneity of the data, findings were presented narratively based on the type of OT and parenting outcomes. Current evidence strongly suggests that parental OT levels are positively related to parental touch and parental gaze and affect synchrony and observer-coded parent-infant bonding. No gender difference in OT levels was observed between fathers and mothers, but OT strengthens affectionate parenting in mothers and stimulatory parenting in fathers. Child OT levels were also positively associated with parental OT levels. Family and healthcare providers could encourage more positive touch and interactive play between parent and child to strengthen parent-child relationships.

Peripheral oxytocin concentrations in psychiatric disorders - A systematic review and methanalysis: Further evidence

Increased interest in understanding how changes in the oxytocinergic system are associated with the etiology and progression of psychiatric disorders has currently boosted the publication of studies. We present a systematic literature review followed by meta-analyses assessing whether peripheral oxytocin (OXT) levels among psychiatric patients differ from healthy controls, considering the moderating role of methodological aspects and samples' characteristics. The following electronic databases were searched: PubMed, Web of Science, PsycINFO, SciELO, LILACS, and Scopus. Fifty-five papers were included in the analysis, and nine independent meta-analyses were performed according to the different diagnoses. Lower OXT concentrations were found in groups of specific disorders (i.e., schizophrenia, restricting and binge-eating/purging subtypes of anorexia nervosa, and borderline personality disorder) with medium to large effect sizes. Great heterogeneity was found among the studies, so that caution is needed to interpret the results. High OXT levels with an effect size of the same magnitude were found for bipolar disorder - type I and obsessive disorder. In contrast, no differences were found for bulimia, autism spectrum, depression, or social anxiety. No meta-analyses were performed for body dysmorphic disorder, post-traumatic stress disorder, or trichotillomania because only one study was identified for each of these disorders. Altered endogenous OXT concentrations are found in several disorders addressed and must be analyzed according to each disorder's specificities.

Social Behavior as a Transdiagnostic Marker of Resilience

The recent shift from psychopathology to resilience and from diagnosis to functioning requires the construction of transdiagnostic markers of adaptation. This review describes a model of resilience that is based on the neurobiology of affiliation and the initial condition of mammals that mature in the context of the mother's body and social behavior. The model proposes three tenets of resilience-plasticity, sociality, and meaning-and argues that coordinated social behavior stands at the core sustaining resilience. Two lines in the maturation of coordinated social behavior are charted, across animal evolution and throughout human development, culminating in the mature human reciprocity of empathy, mutuality, and perspective-taking. Cumulative evidence across ages and clinical conditions and based on our behavioral coding system demonstrates that social reciprocity, defined by plasticity at the individual, dyadic, and group levels, denotes resilience, whereas the two poles of disengagement/avoidance and intrusion/rigidity characterize specific psychopathologies, each with a distinct behavioral signature. Attention to developmentally sensitive markers and to the dimension of meaning in human sociality may open new, behavior-based pathways to resilience.

Early maternal and paternal caregiving moderates the links between preschoolers' reactivity and regulation and maturation of the HPA-immune axis

While early caregiving and child's temperamental dispositions work in concert to shape social-emotional outcomes, their unique and joint contribution to the maturation of the child's stress and immune systems remain unclear. We followed children longitudinally from infancy to preschool to address the buffering effect of early parenting on the link between temperamental dysregulation and hypothalamic-pituitary-adrenal (HPA)-immune axis in preschool-aged children. Participants included 47 typically developing children and their 94 parents in both mother-father and two-father families followed across the first 4-years of family formation. In infancy, we observed parent-infant synchrony and measured parental oxytocin; in preschool, we observed temperamental reactivity and self-regulation and assessed children's cortisol and secretory Immunoglobulin A (s-IgA), biomarkers of the stress and immune systems. Greater self-regulation and lower negative emotionality were associated with lower baseline s-IgA and cortisol, respectively. However, these links were defined by interactive effects so that preschoolers with low self-regulation displayed higher s-IgA levels only in cases of low parent-infant synchrony and negative emotionality linked with greater baseline cortisol levels only when parental oxytocin levels were low. Results emphasize the long-term stress-buffering role of the neurobiology of parental care, demonstrate comparable developmental paths for mothers and fathers, and delineate the complex developmental cascades to the maturation of children's stress-management systems.

Hypothalamic Gene Expression and Postpartum Behavior in a Genetic Rat Model of Depression

Postpartum depression is a complex illness that often occurs in genetically predisposed individuals. Closely related inbred rat strains are a great resource to identify novel causative genes and mechanisms underlying complex traits such as postpartum behavior. We report differences in these behaviors between the inbred depression model, Wistar Kyoto (WKY) More Immobile (WMI), and the isogenic control Wistar Kyoto Less Immobile (WLI) dams. WMI dams showed significantly lower litter survival rate and frequency of arched back and blanket nursing, but increased pup-directed licking, grooming, and retrieval during postpartum days (PPD) 1-10, compared to control WLIs. This increased pup-directed behavior and the frequency of self-directed behaviors segregated during selective breeding of the progenitor strain of WKY, which is also a depression model. These behaviors are manifested in the WMIs in contrast to those of WLIs. Furthermore, habitual differences in the self-directed behavior between light and dark cycles present in WLIs were missing in WMI dams. Hypothalamic transcript levels of the circadian rhythm-related gene Lysine Demethylase 5A (Kdm5a), period 2 (Per2), and the maternal behavior-related oxytocin receptor (Oxtr), vasopressin (Avp), and vasopressin receptor 1a (Avpr1a) were significantly greater in the post-weaning WMI dams at PPD 24 compared to those of WLIs, and also to those of WMI dams whose litter died before PPD 5. Expression correlation amongst genes differed in WLI and WMI dams and between the two time-points postpartum, suggesting genetic and litter-survival differences between these strains affect transcript levels. These data demonstrate that the genetically close, but behaviorally disparate WMI and WLI strains would be suitable for investigating the underlying genetic basis of postpartum behavior.

Concordance in parent and offspring cortico-basal ganglia white matter connectivity varies by parental history of major depressive disorder and early parental care

Social behavior is transmitted cross-generationally through coordinated behavior within attachment bonds. Parental depression and poor parental care are major risks for disruptions of such coordination and are associated with offspring's psychopathology and interpersonal dysfunction. Given the key role of the cortico-basal ganglia (CBG) circuits in social communication, we examined similarities (concordance) of parent-offspring CBG white matter (WM) connections and how parental history of major depressive disorder (MDD) and early parental care moderate these similarities. We imaged 44 parent-offspring dyads and investigated WM connections between basal-ganglia seeds and selected regions in temporal cortex using diffusion tensor imaging (DTI) tractography. We found significant concordance in parent-offspring strength of CBG WM connections, moderated by parental lifetime-MDD and care. The results showed diminished neural concordance among dyads with a depressed parent and that better parental care predicted greater concordance, which also provided a protective buffer against attenuated concordance among dyads with a depressed parent. Our findings provide the first neurobiological evidence of concordance between parents-offspring in WM tracts and that concordance is diminished in families where parents have lifetime-MDD. This disruption may be a risk factor for intergenerational transmission of psychopathology. Findings emphasize the long-term role of early caregiving in shaping the neural concordance among at-risk and affected dyads.

Chronic Depression Alters Mothers' DHEA and DEHA-to-Cortisol Ratio: Implications for Maternal Behavior and Child Outcomes

Maternal depression is a major public health problem that typically occurs in the period surrounding childbirth. The neurobiological mechanisms underlying maternal depression have been the focus of increasing research and studies pointed to the crucial role of the HPA axis in this disorder. However, most studies focused on cortisol expression and regulation while recent attention has shifted to include the sulfate steroids DHEA and DHEA-S. A community cohort of 1,983 women with no comorbid risk was recruited at birth and depression was assessed periodically across the first postpartum year. At 6 years, 156 families were re-visited: 46 mothers were defined as chronically-depressed and 103 controls reported no depression from birth to six years. Mothers and children were diagnosed by structured psychiatric interviews and mother-child interactions were observed. Maternal diurnal cortisol (CT) and dehydroepiandrosterone (DHEA) were assessed. Depressed mothers had lower levels of DHEA (AUCg), flattened DHEA diurnal variability (AUCi), and smaller DHEA-to-CT Ratio. Regression analysis demonstrated that maternal sensitivity during mother-child interaction was independently predicted by maternal depression, DHEA levels, child CT, and child social withdrawal. Results underscore the need for multi-level understanding of the dynamic interplay between maternal psychopathology, mother-child relationship, and pituitary-adrenal-cortex-to-medulla balance in studying the cross generational transfer of psychiatric vulnerability from depressed mothers to their children.

What is resilience: an affiliative neuroscience approach

Resilience - a key topic in clinical science and practice - still lacks a clear conceptualization that integrates its evolutionary and human-specific features, refrains from exclusive focus on fear physiology, incorporates a developmental approach, and, most importantly, is not based on the negation (i.e., absence of symptoms following trauma). Building on the initial condition of mammals, whose brain matures in the context of the mother's body and caregiving behavior, we argue that systems and processes that participate in tuning the brain to the social ecology and adapting to its hardships mark the construct of resilience. These include the oxytocin system, the affiliative brain, and biobehavioral synchrony, all characterized by great flexibility across phylogenesis and ontogenesis. Three core features of resilience are outlined: plasticity, sociality and meaning. Mechanisms of sociality by which coordinated action supports diversity, endurance and adaptation are described across animal evolution. Humans' biobehavioral synchrony matures from maternal attuned behavior in the postpartum to adult-adult relationships of empathy, perspective-taking and intimacy, and extends from the mother-child relationship to other affiliative bonds throughout life, charting a fundamental trajectory in the development of resilience. Findings from three high-risk cohorts, each tapping a distinct disruption to maternal-infant bonding (prematurity, maternal depression, and early life stress/trauma), and followed from birth to adolescence/young adulthood, demonstrate how components of the neurobiology of affiliation confer resilience and uniquely shape the social brain.

Postpartum stress and infant outcome: A review of current literature

Postpartum stress has been shown to have an association with infant growth, nutrition, bonding, temperament and ultimately childhood mental wellbeing. When persistent, recurring or chronic, it can negatively impact infant outcome, including the subscales of mental wellbeing such as growth, development, feeding, attachment and sleep. This study aims to define the physical and functional effect of postpartum stress on measures of infant mental wellbeing. A systematic review of English language articles published between 1995 and 2019 on PubMed, Medline and Psych base databases was carried out. Search terms used included postpartum, stress, infant, growth, development, nutrition, attachment and sleep. Both qualitative and quantitative studies were reviewed with eligibility criteria. Inclusion criteria of human studies, mothers diagnosed with depressive and anxiety symptoms postpartum with infant correlates were used. All animal studies and studies with women already on medication were excluded. A total of 74 articles were reviewed and summarized into postpartum stress associations with infant growth, development, nutrition, sleep and maternal fetal attachment. Postpartum stress is negatively associated with poor developmental trajectories and linear growth deficits, causing stunting in growth; poor language and cognitive development; poor gross and fine motor movement, and infant sleep. An inverse relationship exists with breast feeding and postpartum depression. More importantly, breastfeeding efficacy is important for sustaining positive infant feeding outcome. Increased maternal age during postpartum depression has been linked, as a contributing factor, to decreased maternal fetal attachment/bonding. A ripple effect exists from the association between postpartum stress and poor infant sleep. There is strong evidence that correlates PPS to infant outcome, mediated through many external factors. More research needs to be conducted to delineate and potentially mitigate the impact of modifiable factors. Not all articles in the literature were reviewed.

Oxytocin Response Following Playful Mother-Child Interaction in Survivors of the Great East Japan Earthquake

BACKGROUND

Children who are exposed to natural disasters are at greater risk of developing mental and behavior problems. Prior studies have suggested that positive parenting practices could prevent child mental and behavior problems among those who were exposed to natural disasters. Parent-child interaction increases oxytocin level in parents and infants; however, studies assessing the change in oxytocin level after positive parent-child interaction and its effect on child behavior problems among preadolescents who were exposed to natural disasters are lacking. This study investigated whether playful interaction stimulated oxytocin levels in 34 mother-child dyads who experienced the 2011 Great East Japan Earthquake in Kesennuma City in Miyagi Prefecture, Japan, and the effect of the maternal oxytocin changes on child behavior problems.

METHODS

Participants were recruited in 2012 after the Great East Japan Earthquake. Annual surveys were conducted from 2012 to 2017. Salivary oxytocin level was assessed before and after the playful interaction in 2015. Behavior problems were evaluated by caregivers, using the Child Behavior Checklist (CBCL) in 2017. Fixed effect regression analyses were conducted to determine the effect of playful mother-child interaction on oxytocin level by comparing the change in the 10 min after the interaction with the change in the 10 min before the interaction. We also examined the effect of maternal oxytocin changes before and after the playful interaction on the onset of child behavior problems in 2017.

RESULTS

A significant increase in maternal oxytocin level was detected following playful interaction, especially among mothers of first-born boys (2.63 pg/mg protein. 95% CI: 0.45, 4.81). Maternal psychological distress and trauma were also negatively associated with an increase of oxytocin levels. The increase in maternal oxytocin level was significantly associated with lower externalizing problem score of children 2 years later.

CONCLUSION

Our results might suggest a rational for potential preventive intervention for child behavior problems through playful mother-child interaction after natural disasters.

Intergenerational transmission of depression: clinical observations and molecular mechanisms

Maternal mental illness can have a devastating effect during the perinatal period, and has a profound impact on the care that the baby receives and on the relationships that the baby forms. This review summarises clinical evidence showing the effects of perinatal depression on offspring physical and behavioural development, and on the transmission of psychopathology between generations. We then evaluate a number of factors which influence this relationship, such as genetic factors, the use of psychotropic medications during pregnancy, the timing within the perinatal period, the sex of the foetus, and exposure to maltreatment in childhood. Finally, we examine recent findings regarding the molecular mechanisms underpinning these clinical observations, and identify relevant epigenetic and biomarker changes in the glucocorticoid, oxytocin, oestrogen and immune systems, as key biological mediators of these clinical findings. By understanding these molecular mechanisms in more detail, we will be able to improve outcomes for both mothers and their offspring for generations.

Exposure to early and persistent maternal depression impairs the neural basis of attachment in preadolescence

Maternal depression increases child vulnerability to psychopathology, loneliness, and social maladjustment; yet, its long-term effects on the social brain are unknown. In this prospective longitudinal study we examined the impact of early and persistent maternal depression on the neural basis of attachment in preadolescence. A community cohort was followed in two groups; children exposed to maternal depression from birth to 6 years and healthy controls. At 9 months and 6 years, mother-child interactions were coded for maternal sensitivity and affect synchrony and salivary oxytocin levels were assessed at 6 years. At preadolescence (11-13 years), children underwent magnetoencephalography (MEG) while exposed to own versus unfamiliar mother-child interaction. Own interaction elicited greater response in beta- and gamma-band oscillations across a wide cluster in temporal and insular cortices, including the Superior Temporal Sulcus, Superior Temporal Gyrus, Inferior Temporal Gyrus, and insula. Beta activations were predicted by maternal sensitivity across early childhood and gamma by affect synchrony. Oxytocin was related to beta response to social cues. Maternal depression impacted child's brain response in two ways. First, maternal depression significantly increased the prevalence of child affective disorder and such children showed no neural differentiation between attachment and non-attachment stimuli. Second, maternal depression decreased maternal sensitivity, affect synchrony, and child oxytocin across early childhood and these were longitudinally associated with aberrant neural response to attachment-specific and social-general cues in preadolescence. Our findings are the first to describe mechanisms by which maternal depression impairs the neural basis of attachment at the transition to adolescence and advocate the need for relationship-focused early interventions.

Neural correlates of emotion processing comparing antidepressants and exogenous oxytocin in postpartum depressed women: An exploratory study

Despite common use of antidepressants to treat postpartum depression, little is known about the impact of antidepressant use on postpartum brain activity. Additionally, although oxytocin has been investigated as a potential treatment for postpartum depression, the interaction between antidepressants and exogenous oxytocin on brain activity is unknown. We explored postpartum depressed women's neural activation in areas identified as important to emotion and reward processing and potentially, antidepressant response: the amygdala, nucleus accumbens and ventral tegmental area. We conducted a secondary analysis of a functional imaging study of response to sexual, crying infant and smiling infant images in 23 postpartum depressed women with infants under six months (11 women taking antidepressants, 12 unmedicated). Participants were randomized to receive a single dose of oxytocin or placebo nasal spray. There was significantly higher amygdala activation to sexual stimuli than either neutral or infant-related stimuli among women taking antidepressants or receiving oxytocin nasal spray. Among unmedicated women receiving placebo, amygdala activation was similar across stimuli types. There were no significant effects of antidepressants nor oxytocin nasal spray on reward area processing (i.e., in the nucleus accumbens or ventral tegmental area). Among postpartum women who remain depressed, there may be significant interactions between the effects of antidepressant use and exogenous oxytocin on neural activity associated with processing emotional information. Observed effect sizes were moderate to large, strongly suggesting the need for further replication with a larger sample.

Alteration in oxytocin levels induced by early social environment affects maternal behavior and estrogen receptor alpha in mandarin voles (Microtus mandarinus)

Many studies have shown that the early social environment exerts long-term effects on the brain and also the parental behavior of adults. Oxytocin (OXT) is one of the most important neurotransmitters that regulate social behavior; howerve, whether the early social environment affects parental behavior via OXT remains unclear. Using socially monogamous adult mandarin voles (Microtus mandarinus), the present study found that 1) both paternal deprivation and early social deprivation significantly decreased OXT expression in both the paraventricular hypothalamic nucleus (PVN) and the supraoptic nucleus (SON) of F2 generation offspring; 2) systemic neonatal OXT injection in naïve animals promoted maternal but not paternal behavior in adult F2 offspring; 3) systemic neonatal OXT injection significantly increased ERα expression in both the medial preoptic area (MPOA) and the ventro medial hypothalamic nucleus (VMH) in female but not in male mandarin voles; 4) systemic neonatal administration of an OXT antagonist significantly reduced ERα expression in the bed nucleus of the stria terminalis (BNST), VMH, and the arcuate hypothalamic nucleus (Arc) in females and in all examined brain regions in males. In summary, the obtained data demonstrate that the early social environment could affect OXT level, which in turn leads to long-term effects on ERα expression in relevant brain regions, consequently affecting maternal behavior but not paternal behavior.

Maternal depression impacts child psychopathology across the first decade of life: Oxytocin and synchrony as markers of resilience

BACKGROUND

While maternal depression is known to carry long-term negative consequences for offspring, very few studies followed children longitudinally to address markers of resilience in the context of maternal depression. We focused on oxytocin (OT) and mother-child synchrony - the biological and behavioral arms of the neurobiology of affiliation - as correlates of resilience among children of depressed mothers.

METHOD

A community birth-cohort was recruited on the second postbirth day and repeatedly assessed for maternal depression across the first year. At 6 and 10 years, mothers and children underwent psychiatric diagnosis, mother-child interactions were coded for maternal sensitivity, child social engagement, and mother-child synchrony, children's OT assayed, and externalizing and internalizing problems reported.

RESULTS

Exposure to maternal depression markedly increased child propensity to develop Axis-I disorder at 6 and 10 years. Child OT showed main effects for both maternal depression and child psychiatric disorder at 6 and 10 years, with maternal or child psychopathology attenuating OT response. In contrast, maternal depression decreased synchrony at 6 years but by 10 years synchrony showed only child disorder effect, highlighting the shift from direct to indirect effects as children grow older. Path analysis linking maternal depression to child externalizing and internalizing problems at 10 years controlling for 6-year variables indicated that depression linked with decreased maternal sensitivity and child OT, which predicted reduced child engagement and synchrony, leading to higher externalizing and internalizing problems. OT and synchrony mediated the effects of maternal depression on child behavior problems and an alternative model without these resilience components provided less adequate fit.

CONCLUSIONS

Maternal depression continues to play a role in children's development beyond infancy. The mediating effects of OT and synchronous, mutually regulated interactions underscore the role of plasticity in resilience. Results emphasize the need to follow children of depressed mothers across middle childhood and construct interventions that bolster age-appropriate synchrony.

Maternal depression alters stress and immune biomarkers in mother and child

BACKGROUND

Exposure to maternal depression bears long-term negative consequences for children's well-being. Yet, no study has tested the joint contribution of maternal and child's hypothalamic pituitary axis and immune systems in mediating the effects of maternal depression on child psychopathology.

METHODS

We followed a birth cohort over-represented for maternal depression from birth to 10 years (N = 125). At 10 years, mother and child's cortisol (CT) and secretory immunoglobulin A (s-IgA), biomarkers of the stress and immune systems, were assayed, mother-child interaction observed, mothers and children underwent psychiatric diagnosis, and children's externalizing and internalizing symptoms reported.

RESULTS

Depressed mothers had higher CT and s-IgA levels and displayed more negative parenting, characterized by negative affect, intrusion, and criticism. Children of depressed mothers exhibited more Axis-I disorders, higher s-IgA levels, and greater social withdrawal. Structural equation modeling charted four paths by which maternal depression impacted child externalizing and internalizing symptoms: (a) increasing maternal CT, which linked with higher child CT and behavior problems; (b) augmenting maternal and child's immune response, which were associated with child symptoms; (c) enhancing negative parenting that predicted child social withdrawal and symptoms; and (d), via a combined endocrine-immune pathway suppressing symptom formation.

CONCLUSIONS

Our findings, the first to test stress and immune biomarkers in depressed mothers and their children in relation to social behavior, describe mechanisms of endocrine synchrony in shaping children's stress response and immunity, advocate the need to follow the long-term effects of maternal depression on children's health throughout life, and highlight maternal depression as an important public health concern.

The Oxytocin Receptor: From Intracellular Signaling to Behavior

The many facets of the oxytocin (OXT) system of the brain and periphery elicited nearly 25,000 publications since 1930 (see FIGURE 1 , as listed in PubMed), which revealed central roles for OXT and its receptor (OXTR) in reproduction, and social and emotional behaviors in animal and human studies focusing on mental and physical health and disease. In this review, we discuss the mechanisms of OXT expression and release, expression and binding of the OXTR in brain and periphery, OXTR-coupled signaling cascades, and their involvement in behavioral outcomes to assemble a comprehensive picture of the central and peripheral OXT system. Traditionally known for its role in milk let-down and uterine contraction during labor, OXT also has implications in physiological, and also behavioral, aspects of reproduction, such as sexual and maternal behaviors and pair bonding, but also anxiety, trust, sociability, food intake, or even drug abuse. The many facets of OXT are, on a molecular basis, brought about by a single receptor. The OXTR, a 7-transmembrane G protein-coupled receptor capable of binding to either Gαior Gαqproteins, activates a set of signaling cascades, such as the MAPK, PKC, PLC, or CaMK pathways, which converge on transcription factors like CREB or MEF-2. The cellular response to OXT includes regulation of neurite outgrowth, cellular viability, and increased survival. OXTergic projections in the brain represent anxiety and stress-regulating circuits connecting the paraventricular nucleus of the hypothalamus, amygdala, bed nucleus of the stria terminalis, or the medial prefrontal cortex. Which OXT-induced patterns finally alter the behavior of an animal or a human being is still poorly understood, and studying those OXTR-coupled signaling cascades is one initial step toward a better understanding of the molecular background of those behavioral effects.

Role of oxytocin in parental behaviour

Both animal and human studies have provided conclusive evidence that oxytocin (OXT) acts in the brain (eg, medial preoptic area, ventral tegmental area, nucleus accumbens) to promote parental behaviour under different reproductive and physiological conditions. OXT appears to accelerate and strengthen the neural process that makes newborns attractive or rewarding. Furthermore, OXT reduces stress/anxiety and might improve mood and well being, resulting in indirect benefits for parents. However, OXT also plays a role in the development of species reproductive and social strategies, making some species or individuals more prone to display caring activities in nonreproductive contexts. There are important differences in the development of the OXT system and its regulation by gonadal hormones that can make individuals or species very different. Those intra- and interspecific differences in the OXT system have been associated with differences in parental behaviour. For example, differences in OXT levels in body fluids and genetic variants for the OXT and OXT receptor genes have been associated with variability in parental mood and behaviour in humans. Thus, OXT has received much attention as a potential therapeutic agent for affective, emotional and behavioural problems. Despite many preliminary studies indicating promising findings, several unknown aspects of the OXT system remain to be addressed before we can achieve a complete understanding of its function in the brain. The enormous interest that this area of study has attracted in the last decade will likely continually contribute to advancing our understanding of the role of OXT in parental behaviour and other behavioural and physiological functions.

Psychophysiological effects of oxytocin on parent-child interactions: A literature review on oxytocin and parent-child interactions

Oxytocin (OT), often called the 'hormone of love' or 'hormone of attachment,' plays a fundamental role in the establishment and quality of parent-infant bonding. However, emerging evidence indicates that OT can also produce antisocial behavior. To clarify these effects, we review studies examining the role of endogenous and exogenous OT on several determinants of attachment: parental sensitivity, and bonding or synchrony in parent-child dyads. Contextual and individual factors moderating the effect of intranasal OT and its peripheral levels are also reviewed. Finally, potential therapeutic applications for OT and current limitations in human OT research are examined. This systematic literature review was based on the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines, with two electronic databases and other bibliographic sources. We identified a total of 47 relevant studies for inclusion in our review. Most of the findings are in accordance with recent ideas that OT administration may increase parent-child prosocial interaction, showing that OT exerts beneficial effects on processes thought to promote bonding, sensitivity, and synchrony. However, we found that OT can induce antisocial behavior (e.g., anxiety) or adverse effects (modulation of maternal care recollections) that are moderated by different contextual (e.g., maltreatment level, presence of unfamiliar people) and individual (attachment style) factors. This review reinforces the importance of context- and individual-dependent factors, which must be taken into account when analyzing the psychophysiological effects of OT.

Testosterone, oxytocin, and the development of human parental care

The steroid testosterone (T) and neuropeptide oxytocin (OT) have each been implicated in the development of parental care in humans and animals, yet very little research addressed the interaction between these hormones at the transition to parenthood in mothers and fathers. One hundred and sixty mothers and fathers (80 couples) were visited 1 and 6months after the birth of their first child, plasma OT and T were assayed at each time-point, and interactions between each parent and the infant were observed and micro-coded for two key parental behaviors; affectionate touch and parent-infant synchrony. T showed gender-specific effects. While paternal T was individually stable across the first six months of parenting and predicted lower father-infant synchrony, maternal T was neither stable nor predictive of maternal behavior. An interaction of OT and T showed that T has complex modulatory effects on the relations of OT and parenting. Slope analysis revealed that among fathers, only when T was high (+1SD), negative associations emerged between OT and father affectionate touch. In contrast, among mothers, the context of high T was related to a positive association between OT and maternal touch. Our findings, the first to test the interaction of OT and T in relation to observed maternal behavior, underscore the need for much further research on the complex bidirectional effects of steroid and neuropeptide systems on human mothering and fathering.

Oxytocin trajectories and social engagement in extremely premature infants during NICU hospitalization

Extremely premature infants, born 28 weeks gestation or less, are at high risk for impaired socioemotional development, due in part to exposure to early stressful social experiences that alter brain development. Understanding mediators that link experience with outcomes is necessary to assess premature infant responses to social experiences that are critical to brain development. The hormone oxytocin (OT), released during supportive interactions, has potential as a biomarker of the premature infant's responses to social experiences. The purpose of this study was to examine associations among infant plasma OT trajectories and maternal-infant social engagement behaviors during initial hospitalization. This study also examined demographic correlates of engagement behaviors in mothers and infants. Plasma from 28 extremely premature infants, born gestational ages 25-28 6/7 weeks, was collected at 14 days of life, then weekly until 34 weeks. Social engagement behaviors were measured by the Parent-Child Early Relational Assessment during a videotaped feeding when the infant was receiving one-quarter full oral feeds. Maternal-infant demographics were extracted from the medical record. Higher infant plasma OT was associated with lower infant social engagement, but no associations were found with maternal social engagement. Infant social engagement was positively related to maternal social engagement. Maternal parity was related to maternal social engagement, and infant demographics did not predict infant social engagement. The significant, yet negative, association between infant OT and engagement provides support for the measurement of OT as a neurobiological antecedent to infant social behaviors. Finally, this research suggests that during the earliest period of infant socio-behavioral development, premature infants are behaviorally reactive to the social engagement behaviors of their mothers.

Fathering moderates the effects of maternal depression on the family process

Maternal depression negatively impacts children's development, yet few studies have focused on fathering and the family process in cases of maternal depression. A community cohort of married/cohabitating women was recruited on the second postbirth day (N = 1,983) and maternal depression repeatedly assessed across the first year and again at 6 years to form two cohorts: mothers chronically depressed from birth to 6 (N = 46) and nondepressed controls (N = 103). At 6 years, mother–child, father–child, and family interactions were observed. In families of depressed mothers, both mother and father exhibited lower sensitivity and higher intrusiveness, and children displayed lower social engagement during interactions with mother and father. Fathering moderated the effects of maternal depression on the family process. When fathers showed low sensitivity, high intrusiveness, and provided little opportunities for child social engagement, the family process was less cohesive, implying a decrease in the family's harmonious, warm, and collaborative style. However, in cases of high father sensitivity, low intrusiveness, and increased child engagement, the family process was unaffected by maternal depression. Findings describe both comparability and compensatory mechanisms in the effects of fathering on family life when maternal care is deficient, highlight the buffering role of fathers, and underscore the importance of father-focused interventions when mothers are depressed.

Oxytocin pathways in the intergenerational transmission of maternal early life stress

Severe stress in early life, such as childhood abuse and neglect, constitutes a major risk factor in the etiology of psychiatric disorders and somatic diseases. Importantly, these long-term effects may impact the next generation. The intergenerational transmission of maternal early life stress (ELS) may occur via pre-and postnatal pathways, such as alterations in maternal-fetal-placental stress physiology, maternal depression during pregnancy and postpartum, as well as impaired mother-offspring interactions. The neuropeptide oxytocin (OT) has gained considerable attention for its role in modulating all of these assumed transmission pathways. Moreover, central and peripheral OT signaling pathways are highly sensitive to environmental exposures and may be compromised by ELS with implications for these putative transmission mechanisms. Together, these data suggest that OT pathways play an important role in the intergenerational transmission of maternal ELS in humans. By integrating recent studies on gene-environment interactions and epigenetic modifications in OT pathway genes, the present review aims to develop a conceptual framework of intergenerational transmission of maternal ELS that emphasizes the role of OT.

The endocrinology of human caregiving and its intergenerational transmission

Variation in the quality of parental care has a tremendous impact on a child's social–emotional development. Research investigating the predictors of this variability in human caregiving behavior has mostly focused on learning mechanisms. Evidence is currently accumulating for the complementary underlying role of steroid hormones and neuropeptides. An overview is provided of the hormones and neuropeptides relevant for human caregiving behavior. Then the developmental factors are described that stimulate variability in sensitivity to these hormones and neuropeptides, which may result in variability in the behavioral repertoire of caregiving. The role of genetic variation in neuropeptide and steroid receptors, the role of testosterone and oxytocin during fetal development and parturition, and the impact of experienced caregiving in childhood on functioning of the neuroendocrine stress and oxytocin system are discussed. Besides providing a heuristic framework for further research on the ontogenetic development of human caregiving, a neuroendocrine model is also presented for the intergenerational transmission of caregiving practices. Insight into the underlying biological mechanisms that bring about maladaptive caregiving behavior, such as neglect and insensitive parenting, will hopefully result in more efficient approaches to reduce the high prevalence of such behavior and to minimize the impact on those affected.

Maternal depression across the first years of life compromises child psychosocial adjustment; relations to child HPA-axis functioning

Maternal depression across the first years of life negatively impacts children's development. One pathway of vulnerability may involve functioning of the hypothalamic-pituitary-adrenal (HPA) axis. We utilize a community cohort of 1983 women with no comorbid risk repeatedly assessed for depression from birth to six years to form two groups; chronically depressed (N=40) and non-depressed (N=91) women. At six years, mother and child underwent psychiatric diagnosis, child salivary cortisol (CT) was assessed three times during a home-visit, mother-child interaction was videotaped, and child empathy was coded from behavioral paradigms. Latent Growth curve Model using Structural Equation Modeling (SEM) estimated the links between maternal depression and mother's negative parenting and three child outcomes; psychopathology, social withdrawal, and empathy as related to child CT baseline and variability. Depressed mothers displayed more negative parenting and their children showed more Axis-I psychopathology and social withdrawal. SEM analysis revealed that maternal depression was associated with reduced CT variability, which predicted higher child psychopathology and social withdrawal. Whereas all children exhibited similar initial levels of CT, children of controls reduced CT levels over time while children of depressed mothers maintained high, non-flexible levels. Mother negativity was related to lower initial CT levels, which predicted decreased empathy. Findings suggest that chronic maternal depression may compromise children's social-emotional adjustment by diminishing HPA-system flexibility as well as limiting the mother's capacity to provide attuned and predictable caregiving.

Mother-preterm infant interactions at 3 months of corrected age: influence of maternal depression, anxiety and neonatal birth weight

Maternal depression and anxiety represent risk factors for the quality of early mother-preterm infant interactions, especially in the case of preterm birth. Despite the presence of many studies on this topic, the comorbidity of depressive and anxious symptoms has not been sufficiently investigated, as well as their relationship with the severity of prematurity and the quality of early interactions. The Aim of this study was to evaluate the quality of early mother-infant interactions and the prevalence of maternal depression and anxiety comparing dyads of extremely low birth weight (ELBW) and very low birth weight (VLBW) preterm infants with full-term ones. Seventy seven preterm infants (32 ELBW; 45 VLBW) and 120 full term (FT) infants and their mothers were recruited. At 3 months of corrected age, 5 min of mother-infant interactions were recorded and later coded through the Global Ratings Scales. Mothers completed the Edinburgh Postnatal Depression Scale and Penn State Worry Questionnaire. Infant levels of development were assessed through the Griffiths Mental Development Scales. A relation emerged among the severity of prematurity, depression, anxiety, and the quality of interactions. When compared with the FT group, the ELBW interactions were characterized by high maternal intrusiveness and low remoteness, while the VLBW dyads showed high levels of maternal sensitivity and infant communication. Depression was related to maternal remoteness and negative affective state, anxiety to low sensitivity, while infant interactive behaviors were impaired only in case of comorbidity. ELBW's mothers showed the highest prevalence of depressive and anxious symptoms; moreover, only in FT dyads, low maternal sensitivity, negative affective state and minor infant communication were associated to the presence of anxious symptoms. The results confirmed the impact of prematurity on mother-infant interactions and on maternal affective state. Early diagnosis can help to plan supportive interventions.