Early temperament as a predictor of later personality

Infant Temperament Is Associated With Milk Cortisol but Not With Maternal Childhood Trauma

Previous studies have suggested that maternal childhood trauma (MCT) may influence infant temperament, but the underlying physiological mechanisms remain unclear. This study sought to confirm the involvement of breast milk cortisol in the link between MCT and infant temperament. The study sample included 90 mother-infant dyads recruited from the urban Polish population. MCT was assessed based on the Early Life Stress Questionnaire (ELSQ) and infant temperamental factors (surgency/extraversion, negative affectivity, and orienting/regulation) using the Infant Behavior Questionnaire-Revised at 12 months of life. Cortisol was assayed in milk samples collected at 5 months of life using the ELISA method. Based on the ELSQ median, the sample was divided into low and high MCT groups. The ANCOVA models with milk cortisol as a covariant were run to check the effect of low versus high MCT on infant temperament. We found a positive association between milk cortisol and orienting/regulation. Surprisingly, the low and high MCT groups did not significantly differ in milk cortisol. Furthermore, we found that MCT was unrelated to any infant temperamental factor. While recent literature on the association between milk cortisol and infant temperament is inconsistent, our results suggest that high orienting/regulation might be an adaptation to adverse environments such as stress. Moreover, the infant's temperament appears to be more responsive to the current exposition to maternal stress than her experience of traumatic stress.

Interactions of perinatal depression versus anxiety and infants' early temperament trajectories

This study examines the interplay between maternal depression/anxiety and infant temperament's developmental trajectory in 1687 Swedish-speaking mother-infant dyads from Uppsala County (2009-2019), Sweden. The sample includes a high proportion of university-educated individuals and a low share of foreign-born participants. Maternal depressive and anxiety symptoms were assessed using the Edinburgh Postnatal Depression Scale during gestational weeks 17 and 32 and postpartum at week 6. Multinomial regression explored associations between maternal variables and infant temperament trajectories at 6 weeks, 12 months, and 18 months. Prenatal anxiety is associated with the high-rising infant difficult temperament trajectory, while prenatal depression/anhedonia is associated with the stable-medium trajectory, attenuated postpartum. Associations between infant temperament and maternal mood depended on timing (pre/postpartum) and symptom type (depression/anhedonia vs. anxiety).

Trait continuity: Can parent-rated infant temperament predict HEXACO personality in early adulthood?

Examining the Raine cohort study, we tested the trait continuity hypothesis by examining the extent that young adults' (25-29 years old) self-reported HEXACO personality can be statistically predicted from multi-dimensional parental temperament ratings collected in infancy (1-2 years old). The study incorporated a lagged design (two waves), a large sample size (n = 563), and examined both temperament and personality as both dimensions and profiles. Overall, we found very limited evidence of trait continuity, with generally very weak and few statistically significant observed associations of infant temperament with early adulthood personality. Relations were weak whether profile or dimension-based operationalizations of both phenomena were adopted. Additionally, controlling for sex affected the relations of temperament and personality only to a small extent for most of the traits, and moderation effects of sex were generally zero-to-trivial in size. Altogether, parent-rated temperament in infancy seems to provide little information about HEXACO personality in early adulthood.

Relationship between the gut microbiota and temperament in children 1-2 years old in Chinese birth cohort

BACKGROUND

Understanding the relationship between the gut microbiota and temperament can provide new insights for the regulation of behavioral intervention in children, which is still lacking research. This study aimed to examine the relationship between the gut microbiota and temperament in a cohort of children in 1 year and 2 years old.

METHODS

This study included a total of 37 children with completed information, in which 51 samples at age 1 and 41 samples at age 2 were received respectively. We collected birth and demographic information. Parents reported their child's temperament characteristics using the Infant Behavior Questionnaire-revised (IBQ-R) and Early Childhood Behavior Questionnaire (ECBQ). Fecal samples were collected from each child at 1 and 2 years old and sequenced with MiSeq sequencer. Multiple linear regressions and linear mixed effect models were used to analyze the relationship between the temperament and their microbiota composition as well as the diversity and effect of gender or age on this relationship.

RESULTS

At age of year 2, Faecalibacterium was negatively associated with high-intensity pleasure and surgency. Bifidobacterium was negatively correlated with Perceptual sensitivity. Results showed no difference about three domains between year 1 and year 2, while gut microbiota showed diversity difference and genera difference. There was no gender and age difference on the relationship between temperament and the gut microbiota.

CONCLUSIONS

Temperament was associated with the gut microbiota over time. The temperament remained stable and the relationship between the gut microbiota and temperament wasn't associated with age and gender.

Stability and structure of infant and toddler temperament in two longitudinal studies in Germany

The present study investigated the factor structure and longitudinal stability of infant and toddler temperament measured with the Infant Behavior Questionnaire-Revised (IBQ-R) and the Early Childhood Behavior Questionnaire (ECBQ) in two German samples. Since the few studies using the German IBQ-R failed to replicate the commonly assumed three factors of infant temperament, another exploration of its factor structure was necessary. Whereas previous stability measurements are usually based on groups with relatively large age ranges, we investigated stability between concrete ages. In Study 1, the IBQ-R was applied in 9- and 12-month-old infants. In Study 2, both questionnaires were applied in 12-, 18-, and 24-month-olds. Factor analyses of the IBQ-R in both studies revealed a two-factor solution comprising Surgency/ Extraversion and Negative Affectivity, replicating earlier findings with German infants. The Orienting/ Regulation factor was not replicated for the IBQ-R, whereas analysis of the ECBQ revealed a three-factor solution for toddlers. The results showed stability of temperament ratings within infancy (Study 1) and toddlerhood (Study 2) as well as between the developmental periods within the second year of life (Study 2). Taken together, the present findings indicate that temperament stability emerges early in life and can be reliably measured using the IBQ-R and ECBQ, whereas the factor structure of temperament in infancy requires further validation.

Can you teach me not to be angry? Relations between temperament and the emotion regulation strategy distraction in 2-year-olds

Little is known about toddlers' acquisition of specific emotion regulation (ER) strategies, and how early ER is shaped by temperament. This study investigated if 24-month-old German toddlers, predominantly from families with high levels of parental education (N = 96, n = 49 male), learned the ER strategy distraction through observational learning, and its interaction with temperament. Increased use of distraction correlated with reduced negative affect. Use of distraction increased through observational learning. Highly active toddlers tended to use active playing activities to distract themselves in a frustrating situation, whereas toddlers with a less active temperament used calmer activities. Toddlers' learning to apply distraction through observational learning was independent of a match between their own temperament and the model's actions.

Maternal nutrients and effects of gestational COVID-19 infection on fetal brain development

BACKGROUND & AIMS

Maternal gestational infection is a well-characterized risk factor for offsprings' development of mental disorders including schizophrenia, autism, and attention deficit disorder. The inflammatory response elicited by the infection is partly directed against the placenta and fetus and is the putative pathogenic mechanism for fetal brain developmental abnormalities. Fetal brain abnormalities are generally irreversible after birth and increase risk for later mental disorders. Maternal immune activation in animals models this pathophysiology. SARS-CoV-2 produces maternal inflammatory responses during pregnancy similar to previously studied common respiratory viruses.

METHOD

Choline, folic acid, Vitamin D, and n-3 polyunsaturated fatty acids are among the nutrients that have been studied as possible mitigating factors for effects of maternal infection and inflammation on fetal development. Clinical and animal studies relevant to their use in pregnant women who have been infected are reviewed.

RESULTS

Higher maternal choline levels have positive effects on the development of brain function for infants of mothers who experienced viral infections in early pregnancy. No other nutrient has been studied in the context of viral inflammation. Vitamin D reduces pro-inflammatory cytokines in some, but not all, studies. Active folic acid metabolites decrease anti-inflammatory cytokines. N-3 polyunsaturated fatty acids have no effect.

CONCLUSIONS

Vitamin D and folic acid are already supplemented in food additives and in prenatal vitamins. Despite recommendations by several public health agencies and medical societies, choline intake is often inadequate in early gestation when the brain is forming. A public health initiative for choline supplements during the pandemic could be helpful for women planning or already pregnant who also become exposed or infected with SARS-CoV-2.

Male fetus susceptibility to maternal inflammation: C-reactive protein and brain development

BACKGROUND

Maternal inflammation in early pregnancy has been identified epidemiologically as a prenatal pathogenic factor for the offspring's later mental illness. Early newborn manifestations of the effects of maternal inflammation on human fetal brain development are largely unknown.

METHODS

Maternal infection, depression, obesity, and other factors associated with inflammation were assessed at 16 weeks gestation, along with maternal C-reactive protein (CRP), cytokines, and serum choline. Cerebral inhibition was assessed by inhibitory P50 sensory gating at 1 month of age, and infant behavior was assessed by maternal ratings at 3 months of age.

RESULTS

Maternal CRP diminished the development of cerebral inhibition in newborn males but paradoxically increased inhibition in females. Similar sex-dependent effects were seen in mothers' assessment of their infant's self-regulatory behaviors at 3 months of age. Higher maternal choline levels partly mitigated the effect of CRP in male offspring.

CONCLUSIONS

The male fetal-placental unit appears to be more sensitive to maternal inflammation than females. Effects are particularly marked on cerebral inhibition. Deficits in cerebral inhibition 1 month after birth, similar to those observed in several mental illnesses, including schizophrenia, indicate fetal developmental pathways that may lead to later mental illness. Deficits in early infant behavior follow. Early intervention before birth, including prenatal vitamins, folate, and choline supplements, may help prevent fetal development of pathophysiological deficits that can have life-long consequences for mental health.

Maternal choline and respiratory coronavirus effects on fetal brain development

Prenatal COVID-19 infection is anticipated by the U.S. Centers for Disease Control to affect fetal development similarly to other common respiratory coronaviruses through effects of the maternal inflammatory response on the fetus and placenta. Plasma choline levels were measured at 16 weeks gestation in 43 mothers who had contracted common respiratory viruses during the first 6-16 weeks of pregnancy and 53 mothers who had not. When their infants reached 3 months of age, mothers completed the Infant Behavior Questionnaire-Revised (IBQ-R), which assesses their infants' level of activity (Surgency), their fearfulness and sadness (Negativity), and their ability to maintain attention and bond to their parents and caretakers (Regulation). Infants of mothers who had contracted a moderately severe respiratory virus infection and had higher gestational choline serum levels (≥7.5 mM consistent with U.S. Food and Drug Administration dietary recommendations) had significantly increased development of their ability to maintain attention and to bond with their parents (Regulation), compared to infants whose mothers had contracted an infection but had lower choline levels (<7.5 mM). For infants of mothers with choline levels ≥7.5 μM, there was no effect of viral infection on infant IBQ-R Regulation, compared to infants of mothers who were not infected. Higher choline levels obtained through diet or supplements may protect fetal development and support infant early behavioral development even if the mother contracts a viral infection in early gestation when the brain is first being formed.

Epigenetic tuning of brain signal entropy in emergent human social behavior

BACKGROUND

How the brain develops accurate models of the external world and generates appropriate behavioral responses is a vital question of widespread multidisciplinary interest. It is increasingly understood that brain signal variability-posited to enhance perception, facilitate flexible cognitive representations, and improve behavioral outcomes-plays an important role in neural and cognitive development. The ability to perceive, interpret, and respond to complex and dynamic social information is particularly critical for the development of adaptive learning and behavior. Social perception relies on oxytocin-regulated neural networks that emerge early in development.

METHODS

We tested the hypothesis that individual differences in the endogenous oxytocinergic system early in life may influence social behavioral outcomes by regulating variability in brain signaling during social perception. In study 1, 55 infants provided a saliva sample at 5 months of age for analysis of individual differences in the oxytocinergic system and underwent electroencephalography (EEG) while listening to human vocalizations at 8 months of age for the assessment of brain signal variability. Infant behavior was assessed via parental report. In study 2, 60 infants provided a saliva sample and underwent EEG while viewing faces and objects and listening to human speech and water sounds at 4 months of age. Infant behavior was assessed via parental report and eye tracking.

RESULTS

We show in two independent infant samples that increased brain signal entropy during social perception is in part explained by an epigenetic modification to the oxytocin receptor gene (OXTR) and accounts for significant individual differences in social behavior in the first year of life. These results are measure-, context-, and modality-specific: entropy, not standard deviation, links OXTR methylation and infant behavior; entropy evoked during social perception specifically explains social behavior only; and only entropy evoked during social auditory perception predicts infant vocalization behavior.

CONCLUSIONS

Demonstrating these associations in infancy is critical for elucidating the neurobiological mechanisms accounting for individual differences in cognition and behavior relevant to neurodevelopmental disorders. Our results suggest that an epigenetic modification to the oxytocin receptor gene and brain signal entropy are useful indicators of social development and may hold potential diagnostic, therapeutic, and prognostic value.

Interaction of maternal choline levels and prenatal Marijuana's effects on the offspring

BACKGROUND

This study investigated whether higher maternal choline levels mitigate effects of marijuana on fetal brain development. Choline transported into the amniotic fluid from the mother activates α7-nicotinic acetylcholine receptors on fetal cerebro-cortical inhibitory neurons, whose development is impeded by cannabis blockade of their cannabinoid-1(CB1) receptors.

METHODS

Marijuana use was assessed during pregnancy from women who later brought their newborns for study. Mothers were informed about choline and other nutrients, but not specifically for marijuana use. Maternal serum choline was measured at 16 weeks gestation.

RESULTS

Marijuana use for the first 10 weeks gestation or more by 15% of mothers decreased newborns' inhibition of evoked potentials to repeated sounds (d' = 0.55, p < 0.05). This effect was ameliorated if women had higher gestational choline (rs = -0.50, p = 0.011). At 3 months of age, children whose mothers continued marijuana use through their 10th gestational week or more had poorer self-regulation (d' = -0.79, p < 0.05). This effect was also ameliorated if mothers had higher gestational choline (rs = 0.54, p = 0.013). Maternal choline levels correlated with the children's improved duration of attention, cuddliness, and bonding with parents.

CONCLUSIONS

Prenatal marijuana use adversely affects fetal brain development and subsequent behavioral self-regulation, a precursor to later, more serious problems in childhood. Stopping marijuana use before 10 weeks gestational age prevented these effects. Many mothers refuse to cease use because of familiarity with marijuana and belief in its safety. Higher maternal choline mitigates some of marijuana's adverse effects on the fetus.

Prospects for improving future mental health of children through prenatal maternal micronutrient supplementation in China

Prenatal micronutrients in pregnant women's diets, including supplements, have an essential role in fetal brain development and may reduce the risk of mental disorders in offspring. Folic acid, vitamin D, omega-3 fatty acids, and choline have been investigated for this purpose. Folic acid supplementation throughout pregnancy has well-established positive effects. Vitamin D, administered to the mother before birth or to the newborn, has also been shown to reduce the risk of neurodevelopmental disorders. Omega-3 fatty acids during pregnancy have a more uncertain role, with recent trials questioning a beneficial effect on cognition and attention deficit disorder, despite positive effects on prematurity and neonatal wheezing prevention. Choline supplementation is associated with positive effects on cognition and behavior, including early behaviors associated with the development of autism and schizophrenia. There is no experience yet with COVID-19, but adverse effects on fetal brain development of most common coronaviruses are mitigated by higher choline levels. Maternal dietary supplementation of nutrients is a benign and inexpensive intervention in pregnancy to prevent life-long disability from mental illness. Use of dietary supplements in poorer, rural areas of China is below recommendations. Physicians, midwives, and public health officials in China can promote prenatal nutrient supplementation to reduce the future burden of mental illnesses that might be prevented before birth.

Higher Gestational Choline Levels in Maternal Infection Are Protective for Infant Brain Development

OBJECTIVE

To assess whether maternal choline decreases effects of mothers' infections on fetal brain circuit development and on expression of infant behavior at 1 year of age.

STUDY DESIGN

A cross-sectional study was conducted in a public hospital obstetrics and midwifery service, with prenatal assessments of maternal infection, C-reactive protein, and choline level and postnatal assessments of cerebral neuronal inhibition in 162 newborns. At 1 year, 136 parents completed reports of their child's behavior.

RESULTS

Maternal infection at 16 weeks of gestation, experienced by 41% of mothers, raised mean maternal C-reactive protein (d' = 0.47, P = .002) and decreased the development of cerebral inhibition of auditory response at 1 month of age (d' = 0.39, P < .001). Decreased newborn cerebral inhibition manifested as decreased behavioral self-regulation at 1 year. Greater choline levels in mothers with infections were associated with improved newborn inhibition of auditory cerebral response, mitigating the effect of infection (β = -0.34 [95% CI, -5.35 to -0.14], P = .002). At 1 year of age, children of mothers with infection and greater gestational choline levels had improved development of self-regulation, approaching the level of children of mothers without infection (β = 0.29 [95% CI 0.05-0.54], P = .03).

CONCLUSIONS

Greater maternal choline, recommended by the American Medical Association as a prenatal supplement, is associated with greater self-regulation among infants who experienced common maternal infections during gestation. Behavioral problems with diminished self-regulation often lead to referrals to pediatricians and might lead to later mental illness.

Personality development in the context of individual traits and parenting dynamics

Our conceptualization of adult personality and childhood temperament can be closely aligned in that they both reflect endogenous, likely constitutional dispositions. Empirical studies of temperament have focused on measuring systematic differences in emotional reactions, motor responses, and physiological states that we believe may contribute to the underlying biological components of personality. Although this work has provided some insight into the early origins of personality, we still lack a cohesive developmental account of how personality profiles emerge from infancy into adulthood. We believe the moderating impact of context could shed some light on this complex trajectory. We begin this article reviewing how researchers conceptualize personality today, particularly traits that emerge from the Five Factor Theory (FFT) of personality. From the temperament literature, we review variation in temperamental reactivity and regulation as potential underlying forces of personality development. Finally, we integrate parenting as a developmental context, reviewing empirical findings that highlight its important role in moderating continuity and change from temperament to personality traits.