Infant colic and HPA axis development across childhood.

This study examines the long-term impact of infant colic on Hypothalamic-Pituitary-Adrenal (HPA) axis development and the moderating role of attachment security, in a low-risk Dutch sample of 193 children. We assessed infant colic at 6 weeks, circadian cortisol concentrations at ages 1, 2.5, 6, and 10 years, and attachment security at 1 year. Findings indicated that infant colic was associated with steeper diurnal cortisol slopes and slightly higher cortisol concentrations throughout childhood. Attachment security did not moderate these associations. This is the first study to reveal a link between infant colic and the development of the HPA axis in healthy children beyond infancy. These findings have important implications for understanding early risk and protective factors in the stress system's development.

Adolescents' hair cortisol concentrations during COVID-19: Evidence from two longitudinal studies in the Netherlands and the United States.

BACKGROUND: Prolonged stress exposure is associated with alterations in cortisol output. The COVID-19 pandemic represented a stressor for many, including children. However, a high-quality caregiving environment may protect against psychological problems and possibly against elevations in cortisol. We examined adolescents' physiological stress responses to the pandemic and the role of attachment in two longitudinal samples from the Netherlands and the United States (https://aspredicted.org/HHY_8MK). METHODS: Cortisol was assessed from hair samples before and during the pandemic, while attachment was self-reported prepandemic. Study 1 included a Dutch sample (N = 158; examined at ages 10 and later at 14 years old), whereas Study 2 included a US sample (N = 153; examined at ages 9-11 and again 2 years later) and an age-matched prepandemic sample (N = 29, 10-13 years old). Repeated-measures analyses of variance examined changes in cortisol from prepandemic to during the pandemic and the effect of attachment in each sample separately. RESULTS: After accounting for age, both studies revealed nonsignificant changes in hair cortisol and a nonsignificant effect of attachment. A significant effect of sex emerged in Study 1, with Dutch girls showing a significant cortisol increase during the pandemic, which was not explained by puberty. CONCLUSION: These findings suggest differential associations of the pandemic with hair cortisol increases by sex and country.

Determinants of maternal breast milk cortisol increase: Examining dispositional and situational factors.

BACKGROUND: Breast milk is a rich nutritional source, containing numerous proteins, carbohydrates, and hormones that impact long-term offspring development. Strikingly, predictors and correlates of breast milk composition remain largely unknown. Building on a previously discovered increase in breast milk cortisol concentration from 2 to 12 weeks postpartum, we investigated potential predictors of maternal breast milk cortisol in the first three months post-delivery by examining a suite of maternal dispositional (e.g., attachment, adverse childhood experiences or ACEs) and situational factors (e.g., partner support, self-efficacy). METHODS: Data from 73 mothers were collected prenatally, at birth, and 2-, 6- and 12 weeks postpartum. The analyses, which sought to predict postnatal changes in breast milk cortisol, included a pool of theoretically-sound constructs (Table 1) and an exploratory data-driven approach. We fit models differing in complexity as preregistered: 1) Random Forest models, capable of modeling interactions and non-linear relationships, and 2) Bayesian linear models, allowing to model change over time while less prone to overfitting. RESULTS: Overall, we found that no single variable had strong predictive value beyond the known predictors of cortisol, such as time since awakening and time of collection. However, results from both models suggest that ACEs carry information that warrants future investigations, pointing towards a negative relationship with cortisol concentration in breast milk, albeit with a minimal effect size. CONCLUSION: Using sophisticated models, we found that early life stress may play a role in physiological stress markers in breast milk in the first three months postpartum, with potential implications for offspring development.

Are adolescent diet quality and emotional eating predicted by history of maternal caregiving quality and concurrent inhibitory control?

The risk for unhealthy eating behaviour, including poor diet quality and emotional eating, is heightened in adolescence and could result in profound and long-lasting psychological and physical implications. Caregiving quality and adolescents' regulatory skills, such as inhibitory control, may play an essential role in the development of adolescent eating behaviour. This preregistered study investigated whether maternal caregiving throughout the first 14 years of life predicts adolescent diet quality and emotional eating and whether potential associations are mediated by adolescents' inhibitory control. In this low-risk community cohort, maternal caregiving quality was observed at child ages five weeks, 12 months, 2.5, 10, and 14 years. At age 14, diet quality and emotional eating were assessed through self-report. Adolescent inhibitory control was assessed with three behavioural tasks and a maternal report. Mediation analyses were performed with structural equation modelling in R. No evidence was found for links between maternal caregiving quality and adolescent diet quality and emotional eating. Higher levels of adolescent inhibitory control predicted better adolescent diet quality. Longitudinal and experimental studies are needed to investigate directionality, and replication studies are needed in more representative samples (e.g. including high-risk families). Such studies will shed further light on potential links between the history of caregiving behaviour and adolescent regulatory and eating behaviour.

Breastfeeding and room-sharing during COVID-19 in the Netherlands: The impact of perinatal healthcare support.

AIM: The recommendations of 6 months of exclusive breastfeeding (EBF) and parent-infant room-sharing (RS) are often not followed. As these early caregiving practices may have been affected by the COVID-19-related restrictions, we documented BF and RS practices in the Netherlands (2020-2021) and the effects of perceived perinatal healthcare support. METHODS: Pregnant women and mothers of an infant younger than 6 months (N = 784) completed online questionnaires (e.g., demographic information, the impact of COVID-19 on their lives aspects, infant childcare practices) twice: at the beginning of the pandemic and when the infant reached 6 months of age. RESULTS: The pandemic EBF practices mirrored pre-pandemic Dutch reports (17.8 %; Mduration = 3.4 months), while RS rates and duration seemingly doubled (30.6 %; Mduration = 3.98 months). Higher maternal education (r = 0.18) and multiparity (r = 0.08) were significantly associated with longer EBF, and similarly for education (r = 0.17) and multiparity (r = 0.11) with RS durations. Higher perceived perinatal healthcare support predicted shorter RS duration [ß = -0.509, t(5,596) = -2.27, p = .023]. CONCLUSION: While the COVID-19 pandemic did not impact EBF, it may have promoted RS. The negative association between perinatal healthcare support and RS may suggest that parents who need more support from their providers also experience more challenges adhering to RS recommendations, yet this hypothesis remains to be corroborated.

Infants' sensitivity to emotional expressions in actions: The contributions of parental expressivity and motor experience.

Actions can convey information about the affective state of an actor. By the end of the first year, infants show sensitivity to such emotional information in actions. Here, we examined the mechanisms contributing to infants' developing sensitivity to emotional action kinematics. We hypothesized that this sensitivity might rely on two factors: a stable motor representation of the observed action to be able to detect deviations from how it would typically be performed and experience with emotional expressions. The sensitivity of 12- to 13-month-old infants to happy and angry emotional cues in a manual transport action was examined using facial EMG. Infants' own movements when performing an object transport task were assessed using optical motion capture. The infants' caregivers' emotional expressivity was measured using a questionnaire. Negative emotional expressivity of the primary caregiver was significantly related to infants' sensitivity to observed angry actions. There was no evidence for such an association with infants' own motor skill. Overall, our results show that infants' experience with emotions, measured as caregivers' emotional expressivity, may aid infants' discrimination of others' emotions expressed in action kinematics.

Prenatal hair cortisol concentrations during the COVID-19 outbreak: Associations with maternal psychological stress and infant temperament.

BACKGROUND: Maternal psychological stress during pregnancy, including stress resulting from disasters and trauma, has been linked to temperamental difficulties in offspring. Although heightened cortisol concentrations are often hypothesized as an underlying mechanism, evidence supporting this mechanism is not consistent, potentially because of methodological issues and low stress in the population. AIM: To address these issues, this preregistered study investigated the following associations between: 1) prenatal psychological stress and hair cortisol, as a biomarker for chronic stress, during the COVID-19 outbreak (i.e., as a major worldwide psychological stressor), and 2) maternal hair cortisol during the COVID-19 outbreak and later infant temperamental negative affectivity and orienting/regulation. Additionally, we explored whether associations were different for women with low versus high socioeconomic status (SES; maternal education and annual household income) and at different stages of pregnancy. METHOD: Pregnant women (N = 100) filled out online questionnaires during the first COVID-19 lockdown. Six months later, when most mothers were still pregnant or had just given birth, maternal hair samples were collected during home visits. When infants were six months old, mothers reported on their infant's temperament. RESULTS: Although hierarchical regression analyses revealed no associations between prenatal COVID-19 psychological stress and hair cortisol during the COVID-19 outbreak, SES proved to be a moderator in this association. Only pregnant women with higher levels of SES, not lower levels, showed a positive association between work-related and social support-related COVID-19 worries and hair cortisol. Finally, prenatal hair cortisol was not associated with later infant temperamental negative affectivity and orienting/regulation. CONCLUSION: Although the COVID-19 outbreak proved to be a major psychological stressor worldwide, the physiological impact of the crisis might be different for pregnant women with higher SES as compared to lower SES.

Parents of young infants report poor mental health and more insensitive parenting during the first Covid-19 lockdown.

BACKGROUND: The Covid-19 pandemic has put an unprecedented pressure on families with children. How parents were affected by the first Covid-19 lockdown during the early postpartum period, an already challenging period for many, is unknown. AIM: To investigate the associations between Covid-19 related stress, mental health, and insensitive parenting practices in mothers and fathers with young infants during the first Dutch Covid-19 lockdown. METHODS: The Dutch Covid-19 and Perinatal Experiences (COPE-NL) study included 681 parents of infants between 0 and 6 months (572 mothers and 109 fathers). Parents filled out online questionnaires about Covid-19 related stress, mental health (i.e. anxiety and depressive symptoms), and insensitive parenting. Hierarchical regression models were used to analyze the data. RESULTS: Parents of a young infant reported high rates of Covid-19 related stress, with higher reported stress in mothers compared to fathers. Additionally, the percentages of mothers and fathers experiencing clinically meaningful mental health symptoms during the pandemic were relatively high (mothers: 39.7% anxiety, 14.5% depression; fathers: 37.6% anxiety, 6.4% depression). More Covid-19 related stress was associated with more mental health symptoms in parents and increased insensitive parenting practices in mothers. CONCLUSIONS: The results emphasize the strain of the pandemic on young fathers' and mothers' mental health and its potential negative consequences for parenting. As poor parental mental health and insensitive parenting practices carry risk for worse child outcomes across the lifespan, the mental health burden of the Covid-19 pandemic might not only have affected the parents, but also the next generation.

Internalizing symptoms and family functioning predict adolescent depressive symptoms during COVID-19: A longitudinal study in a community sample.

BACKGROUND: The COVID-19 pandemic and lockdown pose a threat for adolescents' mental health, especially for those with an earlier vulnerability. Accordingly, these adolescents may need increased support from family and friends. This study investigated whether family functioning and peer connectedness protects adolescents with earlier internalizing or externalizing symptoms from increased depressive symptoms during the first Dutch COVID-19 lockdown in a low-risk community sample. METHODS: This sample comprised 115 adolescents (Mage = 13.06; 44% girls) and their parents (N = 111) and is part of an ongoing prospective study on child development. Internalizing and externalizing symptoms were self-reported a year before the COVID-19 lockdown. In an online survey during the first Dutch lockdown (April-May 2020), adolescents reported depressive symptoms and perceived peer connectedness, and parents reported family functioning. RESULTS: Twenty-four percent of adolescents reported clinically relevant symptoms of depression during the first COVID-19 lockdown. Depressive symptoms were significantly predicted by earlier internalizing, but not externalizing symptoms. Furthermore, higher quality of family functioning, but not peer connectedness, predicted fewer adolescent depressive symptoms. Family functioning and peer connectedness did not moderate the link between pre-existing internalizing symptoms and later depressive symptoms. CONCLUSIONS: In a low-risk community sample, one-in-four adolescents reported clinically relevant depressive symptoms at the first COVID-19 lockdown. Higher earlier internalizing symptoms and lower quality of family functioning increased risks. These results indicate that even in low-risk samples, a substantial group of adolescents and their families are vulnerable during times of crisis.

The risk and protective factors of heightened prenatal anxiety and depression during the COVID-19 lockdown.

While pregnant women are already at-risk for developing symptoms of anxiety and depression, this is heightened during the COVID-19 pandemic. We compared anxiety and depression symptoms, as indicators of psychological distress, before and during COVID-19, and investigated the role of partner, social network and healthcare support on COVID-19-related worries and consequently on psychological distress. A national survey, conducted during the first lockdown in The Netherlands, assessed COVID-19 experiences and psychological distress (N = 1421), whereas a comparison sample (N = 1439) was screened for psychological distress in 2017-2018. During COVID-19, the percentage of mothers scoring above the questionnaires' clinical cut-offs doubled for depression (6% and 12%) and anxiety (24% and 52%). Women reported increased partner support during COVID-19, compared to pre-pandemic, but decreased social and healthcare support. Higher support resulted in lower COVID-19-related worries, which in turn contributed to less psychological distress. Results suggest that a global pandemic exerts a heavy toll on pregnant women's mental health. Psychological distress was substantially higher during the pandemic than the pre-pandemic years. We identified a protective role of partner, social, and healthcare support, with important implications for the current and future crisis management. Whether increased psychological distress is transient or persistent, and whether and how it affects the future generation remains to be determined.

No evidence for modulation of facial mimicry by attachment tendencies in adulthood: an EMG investigation.

Mimicking another individual functions as a social glue: it smoothens the interaction and fosters affiliation. Here, we investigated whether the intrinsic motivation to affiliate with others, stemming from attachment relationships, modulates individuals' engagement in facial mimicry (FM). Participants (N = 100; MAge = 24.54 years, SDAge = 3.90 years) observed faces with happy, sad, and neutral expressions, while their facial muscle activity was recorded with electromyography. Attachment was measured with the Attachment Styles Questionnaire, which provides a multidimensional profile for preoccupied and dismissing styles. It was proposed that the preoccupied and dismissing styles are characterized by high and low intrinsic affiliation motivation, respectively, and these were hypothesized to manifest in enhanced and diminished FM. Participants showed happy and sad FM, yet attachment styles did not significantly predict FM. Bayes Factor analyses lend evidence favoring the null hypothesis, suggesting that adult attachment do not contribute to FM.

Identifying when children with visual impairment share attention: A novel protocol and the impact of visual acuity.

BACKGROUND: In Coordinated Joint Engagement (CJE), children acknowledge that they and their social partners are paying attention to the same object. The achievement of CJE, critical for healthy development, is at risk in infants with visual impairment (VI). Research on CJE in these children is limited because investigators use a child's gaze switch between social partner and object to index CJE. Research is needed that identifies CJE in children with VI using behaviors that do not require normal vision and that explores the relationship between CJE and visual function. This study aimed to (a) develop a protocol for identifying CJE in children with VI, and (b) explore the relationship between CJE and infants' visual acuity (VA) and contrast sensitivity (CS), measured with Preferential Looking (PL) techniques and Visual Evoked Potential (VEP). METHODS: A protocol that included 9 indices of CJE that did not require normal vision was developed to code videos of 20 infants with VI (mean age =1 year, 6 months, 27 days) and their caregivers. The percentage of CJE episodes in which each index was observed was calculated. Inter-coder reliability was measured using Cohen's Kappa. Linear regression analysis was used to examine the relationship between the infants' visual function and CJE. RESULTS: Inter-rater reliability between a first coder and each of two second coders were 0.98 and 0.90 for determining whether the child participated in CJE. The following indices were observed the most (in 43-62 % of CJE): child's body orientation to caregiver, gaze switch between caregiver and object, and vocalization to caregiver. The only significant model included VA (measured with PL) as a single predictor and explained 26.8 % of the variance in CJE. CONCLUSIONS: The novel protocol can be used to identify CJE in children with VI with good inter-coder reliability. The data suggest that children with lower VA exhibited less CJE.

Five-year-olds' facial mimicry following social ostracism is modulated by attachment security.

Social ostracism triggers an increase in affiliative behaviours. One such behaviour is the rapid copying of others' facial expressions, called facial mimicry. Insofar, it remains unknown how individual differences in intrinsic affiliation motivation regulate responses to social ostracism during early development. We examined children's facial mimicry following ostracism as modulated by individual differences in the affiliation motivation, expressed in their attachment tendencies. Resistant and avoidant tendencies are characterized by high and low affiliation motivation, and were hypothesized to lead to facial mimicry enhancement or suppression towards an ostracizing partner, respectively. Following an ostracism manipulation in which children played a virtual game (Cyberball) with an includer and an excluder peer, mimicry of the two peers' happy and sad facial expressions was recorded with electromyography (EMG). Attachment was assessed via parent-report questionnaire. We found that 5-year-olds smiled to sad facial expressions of the excluder peer, while they showed no facial reactions for the includer peer. Neither resistant nor avoidant tendencies predicted facial mimicry to the excluder peer. Yet, securely attached children smiled towards the excluder peer, when sad facial expressions were displayed. In conclusion, these findings suggest a modulation of facial reactions following ostracism by early attachment.

'Something in the way you move': Infants are sensitive to emotions conveyed in action kinematics.

Body movements, as well as faces, communicate emotions. Research in adults has shown that the perception of action kinematics has a crucial role in understanding others' emotional experiences. Still, little is known about infants' sensitivity to body emotional expressions, since most of the research in infancy focused on faces. While there is some first evidence that infants can recognize emotions conveyed in whole-body postures, it is still an open question whether they can extract emotional information from action kinematics. We measured electromyographic (EMG) activity over the muscles involved in happy (zygomaticus major, ZM), angry (corrugator supercilii, CS) and fearful (frontalis, F) facial expressions, while 11-month-old infants observed the same action performed with either happy or angry kinematics. Results demonstrate that infants responded to angry and happy kinematics with matching facial reactions. In particular, ZM activity increased while CS activity decreased in response to happy kinematics and vice versa for angry kinematics. Our results show for the first time that infants can rely on kinematic information to pick up on the emotional content of an action. Thus, from very early in life, action kinematics represent a fundamental and powerful source of information in revealing others' emotional state.

Correction: The modulation of facial mimicry by attachment tendencies and their underlying affiliation motives in 3-year-olds: An EMG study.

[This corrects the article DOI: 10.1371/journal.pone.0218676.].

The modulation of facial mimicry by attachment tendencies and their underlying affiliation motives in 3-year-olds: An EMG study.

From early in life, facial mimicry represents an important example of implicit non-verbal communication. Facial mimicry is conceived of as the automatic tendency to mimic another person's facial expressions and is thought to serve as a social glue among interaction partners. Although in adults mimicry has been shown to be moderated by the social context and one's needs to affiliate with others, evidence from behavioural mimicry studies suggest that 3-year-olds do not yet show sensitivity to social dynamics. Here, we examined whether attachment tendencies, as a proxy for interindividual differences in affiliation motivation, modulates facial mimicry in 3-year-olds. Resistant and avoidant insecure attachment tendencies are characterized by high and low affiliation motivation, respectively, and these were hypothesized to lead to either enhancement or suppression of mimicry. Additionally, we hypothesized that these effects will be moderated by inhibitory control skills. Facial mimicry of happy and sad expressions was recorded with electromyography (EMG), attachment tendencies were assessed with a parent-report questionnaire and inhibitory control with the gift delay task. The final sample consisted of 42 children, with overall scores suggesting secure attachment. Our findings revealed that 3-year-olds mimicked happy and sad facial expressions. Moreover, resistant tendencies predicted enhanced sad but not happy facial mimicry, whereas avoidant tendencies were not significantly related to mimicry. These effects were not moderated by inhibitory control skills. In conclusion, these findings provide the first evidence for the modulation of mimicry by attachment tendencies and their underlying motivation for affiliation in young children, specifically for negatively-valenced emotional expressions.