Genetic, environmental, and gender effects on individual differences in toddler expressive language

Influence of Respiratory Tract Infections on Vocabulary Growth in Relation to Child's Sex: The STEPS Study

Common health issues have been less examined in studies of early language development, particularly in relation to the child's sex. Respiratory tract infections, often complicated by acute otitis media, are common in children during the first years of life, when early vocabulary development takes place. The present study, conducted in Finland, aimed to investigate whether possible associations between recurrent respiratory tract infections, background factors, and vocabulary growth differ in boys and girls aged 13 to 24 months. The participants (N = 462, 248 boys and 214 girls) were followed for respiratory tract infections and acute otitis media from 0 to 23 months of age. The parents completed daily symptom diaries of respiratory symptoms, physician visits, and diagnoses. The expressive vocabulary was measured with parental reports. We found that recurrent respiratory tract infections were not associated with slower vocabulary development in boys or girls. In fact, boys with recurrent respiratory tract infections had more vocabulary growth during the second year than boys who were less sick. We found that vocabulary growth was associated differently with respiratory tract infections and background factors as a function of the child's sex. The vocabulary growth of boys seems to be more influenced by environmental factors than that of girls.

A broadened estimate of syntactic and lexical ability from the MB-CDI

A critical question in the study of language development is to understand lexical and syntactic acquisition, which play different roles in speech to the extent it would be natural to surmise they are acquired differently. As measured through the comprehension and production of closed-class words, syntactic ability emerges at roughly the 400-word mark. However, a significant proportion of the developmental work uses a coarse combination of function and content words on the MacArthur-Bates Communicative Development Inventory (MB-CDI). Using the MB-CDI Wordbank database, we implemented a factor analytic approach to distinguish between lexical and syntactic development from the Words and Sentences (WS) form that involves both function words and the explicit categorizations. Although the Words and Gestures (WG) form did not share the factor structure, common WG/WS elements recapitulate the expected age-related changes. This parsing of the MB-CDI may prove simple, yet fruitful in subsequent investigation.

Caregiver Language Input Supports Sentence Diversity in Young Children With Autism Spectrum Disorder

PURPOSE

Sentence diversity is a measure of early language development that has yet to be applied to individuals with autism spectrum disorder (ASD). The primary aim of this study was to identify whether children with ASD show change in sentence diversity over 6 months of treatment with Naturalistic Developmental Behavioral Intervention (NDBI). The secondary aim was to examine possible predictors of changes in children's sentence diversity, including caregiver use of NDBI strategies, naturally occurring instances of caregiver Toy Talk, and child characteristics.

METHOD

Fifty children with ASD (ages 2-4 years) and their caregivers, who were receiving NDBI, engaged in two 10-min video-recorded play interactions, 6 months apart. Child speech was transcribed and coded for sentence diversity. Caregiver input was transcribed and coded for naturally occurring Toy Talk. Zero-inflated negative binomial mixed models were used to explore predictors of change in child sentence diversity.

RESULTS

Children's sentence diversity improved over time. Changes in caregiver NDBI strategy use and caregiver baseline Toy Talk were significant predictors of changes in sentence diversity, as were baseline age, nonverbal ratio IQ, and child sex. Additionally, a significant interaction of caregiver baseline Toy Talk and change in caregiver NDBI strategies emerged; the effect of caregiver baseline Toy Talk on children's sentence diversity change was stronger when NDBI strategy use improved.

CONCLUSIONS

Sentence diversity is a developmentally sensitive measure of language development in ASD. NDBI strategies that facilitate reciprocal social communication, combined with input composed of declarative sentences with noun or third-person pronoun subjects, may provide optimal support for children's sentence development.

The Babytwins Study Sweden (BATSS): A Multi-Method Infant Twin Study of Genetic and Environmental Factors Influencing Infant Brain and Behavioral Development

Twin studies can help us understand the relative contributions of genes and environment to phenotypic trait variation, including attentional and brain activation measures. In terms of applying methodologies such as electroencephalography (EEG) and eye tracking, which are key methods in developmental neuroscience, infant twin studies are almost nonexistent. Here, we describe the Babytwins Study Sweden (BATSS), a multi-method longitudinal twin study of 177 MZ and 134 DZ twin pairs (i.e., 622 individual infants) covering the 5-36 month time period. The study includes EEG, eye tracking and genetics, together with more traditional measures based on in-person testing, direct observation and questionnaires. The results show that interest in participation in research among twin parents is high, despite the comprehensive protocol. DNA analysis from saliva samples was possible in virtually all participants, allowing for both zygosity confirmation and polygenic score analyses. Combining a longitudinal twin design with advanced technologies in developmental cognitive neuroscience and genomics, BATSS represents a new approach in infancy research, which we hope to have impact across multiple disciplines in the coming years.

Epigenetic consequences of hormonal interactions between opposite-sex twin fetuses

Previous studies reported inconsistent evidence about some phenotypic traits of females in human opposite-sex twins (opposite-sex females [OSF]) being distinct from females in same-sex twins (SSF). Comparatively, less evidence showed significant differences between males in OS twins (opposite-sex males [OSM]) and males in same-sex twins (SSM). The twin testosterone transfer hypothesis suggests that prenatal exposure of testosterone in utero may be a possible explanation for the differential traits in OSF; however, the underlying mechanism is unknown. Here, we investigated the potential epigenetic effects of hormone interactions and their correlation to the observed phenotypic traits. In the study, DNA methylomic data from 54 newborn twins and histone modification data (H3K4me3, H3K4me1, H3K27me3, and H3K27ac) from 14 newborn twins, including same-sex females (SSF), OS twins, and same-sex males (SSM) were generated. We found that OSF were clearly distinguishable from SSF by DNA methylome, while OSM were distinguishable from SSM by H3K4me1 and H3K4me3. To be more specific, compared to SSF, OSF showed a stronger correlation to males (OSM and SSM) in genome-wide DNA methylation. Further, the DNA methylomic differences between OSF and SSF were linked to the process involving cognitive functions and nervous system regulation. The differential H3K4me3 between OSM and SSM was linked to immune responses. These findings provide epigenetic evidence for the twin testosterone transfer hypothesis and offer novel insights on how prenatal hormone exposure in utero may be linked to the reported differential traits of OS twins.

Dementia risk in women higher in same-sex than opposite-sex twins

INTRODUCTION

Hormones may be one possible mechanism underlying sex differences in dementia incidence. We examined whether presumed differential prenatal hormone milieu is related to dementia risk by comparing dementia rates in same- and opposite-sex dizygotic twin pairs in male and female twins.

METHODS

The sample comprised 43,254 individuals from dizygotic twin pairs aged 60 and older from the Swedish Twin Registry. Survival analyses were conducted separately for females and males.

RESULTS

Female twins from opposite-sex pairs had significantly lower dementia risk than female twins from same-sex pairs, but the differences emerged only after age 70 (hazard ratio = 0.64, P = 0.004). Results were not explained by postnatal risk factors for dementia, and no interaction between twin type and apolipoprotein E (APOE) ε4 was found. Male twins from same-sex versus opposite-sex pairs did not differ significantly.

DISCUSSION

The results suggest that relatively masculine prenatal hormone milieus correlate with lower dementia risk in females.

Opposite-sex and same-sex twin studies of physiological, cognitive and behavioral traits

A scientific interest in opposite-sex (OS) twins comes from animal studies showing hormone transfer between fetuses in utero. A parallel effect in humans may occur, especially for OS females who may be exposed to androgens, in particular testosterone, from the male co-twin. Conversely, OS males may be exposed to lower levels of prenatal testosterone than do same-sex (SS) males. In this special issue, we reviewed published studies investigating potential differences between OS and SS twins in physiological, cognitive and behavioral traits focusing on the Twin Testosterone Transfer (TTT) hypothesis. Sixty articles fulfilled the eligibility criteria including 23 studies published since the review by Tapp et al. (2011). In general, studies of cognition are conflicting, but it is the phenotype for which most support for the TTT hypothesis is found. Less consistent evidence has been found regarding physiological and behavioral traits. We hope that this special issue will stimulate a discussion about how an investigation of the TTT hypothesis should continue in future research.

Characteristics and influence of home literacy environment in early childhood-centered literacy orientation

Background:

The home literacy environment (HLE) and joint parent–child book reading are key factors in children’s language and literacy acquisition. Child-centered literacy orientation (CCLO) refers to the child’s level of engagement in literacy events.

Aim:

To describe the HLE and identify demographic and HLE variables associated with a poor CCLO at 12 months of age.

Methods:

Parents of Singaporean children enrolled in the Growing Up in Singapore Towards healthy Outcomes (GUSTO; n = 1152, birth cohort 2009–2010) completed a childhood literacy questionnaire at 12 months to obtain scores on HLE (0–17) and CCLO (0–6). Logistic regression analyses were employed to identify predictors of low CCLO.

Results:

Parents of 525 children completed the questionnaire. Mothers were the main caregivers in half the households. Mandarin was the main language (34%). Majority of the respondents had a library card that was used less than weekly, and had fewer than 10 children’s books. 18% of parents read to the child daily, of whom one-quarter read at bedtime. Amongst half of the families who had a CCLO score of 0, two-thirds had the lowest HLE scores (0–2). Correlational analyses indicated significant association between HLE with CCLO at 12 months ( p < 0.001). Non-English speaking caregivers and mothers who had only completed primary education were at high risk of a poor 12-month CCLO.

Conclusion:

A literacy-rich home environment is associated with 12-month child-centered literacy orientation. Pediatricians and early years’ professionals may be able to promote benefits of literacy related activities to families at risk of poor child-centered literacy orientation.

Sex Differences in Language Across Early Childhood: Family Socioeconomic Status does not Impact Boys and Girls Equally

Child sex and family socioeconomic status (SES) have been repeatedly identified as a source of inter-individual variation in language development; yet their interactions have rarely been explored. While sex differences are the focus of a renewed interest concerning emerging language skills, data remain scarce and are not consistent across preschool years. The questions of whether family SES impacts boys and girls equally, as well as of the consistency of these differences throughout early childhood, remain open. We evaluated consistency of sex differences across SES and age by focusing on how children (N = 262), from 2;6 to 6;4 years old, from two contrasting social backgrounds, acquire a frequent phonological alternation in French - the liaison. By using a picture naming task eliciting the production of obligatory liaisons, we found evidence of sex differences over the preschool years in low-SES children, but not between high-SES boys and girls whose performances were very similar. Low-SES boys' performances were the poorest whereas low-SES girls' performances were intermediate, that is, lower than those of high-SES children of both sexes but higher than those of low-SES boys. Although all children's mastery of obligatory liaisons progressed with age, our findings showed a significant impeding effect of low-SES, especially for boys.

Stability of core language skill from early childhood to adolescence: a latent variable approach

This four-wave prospective longitudinal study evaluated stability of language in 324 children from early childhood to adolescence. Structural equation modeling supported loadings of multiple age-appropriate multisource measures of child language on single-factor core language skills at 20 months and 4, 10, and 14 years. Large stability coefficients (standardized indirect effect = .46) were obtained between language latent variables from early childhood to adolescence even when accounting for child nonverbal intelligence and social competence and maternal verbal intelligence, education, speech, and social desirability. Stability coefficients were similar for girls and boys. Stability of core language skill was stronger from 4 to 10 to 14 years than from 20 months to 4 years, so early intervention to improve lagging language is recommended.

Testing alternative hypotheses regarding the association between behavioral inhibition and language development in toddlerhood

Studies have reported an inverse association between language development and behavioral inhibition or shyness across childhood, but the direction of this association remains unclear. This study tested alternative hypotheses regarding this association in a large sample of toddlers. Data on behavioral inhibition and expressive and receptive language abilities were collected from 816 twins at ages 14, 20, and 24 months. Growth and regression models were fit to the data to assess the longitudinal associations between behavioral inhibition and language development from 14 to 24 months. Overall, there were significant associations between behavioral inhibition and expressive language, and minimal associations with receptive language, indicating that the association is better explained by reticence to respond rather than deficient language development.

Late talking, typical talking, and weak language skills at middle childhood

To better understand early predictors of weak language and academic abilities, we identified children with and without weak abilities at age 8. We then looked back at age 2 vocabulary and word combining, and evaluated these measures as predictors of age 8 outcomes. More than 60% of children with weak oral language abilities at 8 were not late talkers at 2. However, no word combining at 2 was a significant risk factor for poor oral language, reading comprehension, and math outcomes at 8. The association of no word combining with age 8 reading comprehension and math ability was mediated by age 8 oral language ability. The findings indicate that children take different developmental pathways to weak language abilities in middle childhood. One begins with a delayed onset of language. A second begins with language measures in the typical range, but ends with language ability falling well below typical peers.

Stability of language in childhood: a multiage, multidomain, multimeasure, and multisource study

The stability of language across childhood is traditionally assessed by exploring longitudinal relations between individual language measures. However, language encompasses many domains and varies with different sources (child speech, parental report, experimenter assessment). This study evaluated individual variation in multiple age-appropriate measures of child language derived from multiple sources and stability between their latent variables in 192 young children across more than 2 years. Structural equation modeling demonstrated the loading of multiple measures of child language from different sources on single latent variables of language at ages 20 months and 48 months. A large stability coefficient (r = .84) obtained between the 2 language latent variables. This stability obtained even when accounting for family socioeconomic status, maternal verbal intelligence, education, speech, tendency to respond in a socially desirable fashion, and child social competence. Stability was also equivalent for children in diverse childcare situations and for girls and boys. Across age, from the beginning of language acquisition to just before school entry, aggregating multiple age-appropriate methods and measures at each age and multiple reporters, children show a strong stability of individual differences in general language development.

Wisconsin Twin Panel: Current Directions and Findings

The Wisconsin Twin Panel is based on the population of all twins born in the state of Wisconsin, United States. Our research focus is the etiology and developmental course of early emotions, temperament, childhood anxiety and impulsivity, the autism spectrum, auditory and tactile sensory sensitivity, and related psychobiological and behavioral phenotypes. We employ a range of research methods including structured interviews with caregivers, observer ratings, child self-report, home-based behavioral batteries, biological measures of basal and reactive cortisol, palm prints, birth records, genotyping, cognitive testing, and questionnaires. Reported results highlight the utility of employing multiple modes of assessment when studying child development and psychopathology.

Parameterization of Sex-Limited Autosomal Linkage Analysis for Mx

Incorporation of sex-limitation (genotype-sex interaction) effects into a model of quantitative trait loci (QTL) analysis has been shown to increase the power to detect linkage when analyzing traits in which sex limitation is present (Towne et al., 1997). The present note provides a parameterization of the nonscalar sex-limitation ACE model incorporating autosomal sex-limited QTL effects for use with the Mx matrix algebra program (Neale et al., 2002). An example script designed for use with extended sib- ships that takes advantage of the versatile treatment of covariates within Mx is included.

How Reading Books Fosters Language Development around the World

Research on literacy development is increasingly making clear the centrality of oral language to long-term literacy development, with longitudinal studies revealing the continuity between language ability in the preschool years and later reading. The language competencies that literacy builds upon begin to emerge as soon as children begin acquiring language; thus, the period between birth and age three also is important to later literacy. Book reading consistently has been found to have the power to create interactional contexts that nourish language development. Researchers, pediatricians, and librarians have taken notice of the potential for interventions designed to encourage parents to read with their children. This article reviews research on the connections between language and later reading, environmental factors associated with language learning, and interventions developed in varied countries for encouraging book use by parents of young children.

Evaluating the twin testosterone transfer hypothesis: a review of the empirical evidence

In this paper we review the evidence that fetuses gestated with a male co-twin are masculinized in development, perhaps due to the influence of prenatal androgens: the so-called twin testosterone transfer (TTT) hypothesis. Evidence from studies of behavioral, perceptual, cognitive, morphological and physiological traits in same- and opposite-sex human twins is considered. Apart from two studies reporting increases in aspects of sensation-seeking for females with a male rather than a female co-twin, there is sparse evidence supporting the TTT hypothesis in behavioral studies. Outcomes from studies of perception (in particular otoacoustic emissions) and cognition (in particular vocabulary acquisition and visuo-spatial ability) provide more consistent evidence in support of masculinized performance in twins with a male co-twin compared to twins with a female co-twin. The outcomes favorable to the TTT hypothesis for otoacoustic emissions and visuo-spatial ability are restricted to females. Studies of physiology and morphology (e.g., brain volume, tooth size and 2D:4D ratio) also show some influence of co-twin sex, but again these effects are often restricted to female twins. Because females produce little endogenous testosterone, the effects of gestation with a male co-twin may be more pronounced in females than males. Thus, while uneven, the evidence for the TTT hypothesis is sufficient to warrant further investigation, ideally using large samples of same- and opposite-sex twins, along with control groups of same- and opposite-sex siblings when the characteristics assessed are potentially open to social influences.

Body awareness in preschool children with psychiatric disorder

The purpose of this study was to investigate the body awareness of preschool children with a psychiatric disorder as measured by the test imitation of gestures (Bergès & Lézine, 1978), using the subsections for pointing to body parts (passive vocabulary) and naming body parts (active vocabulary). Seventy-seven children from 37 to 72 months of age with psychiatric disorders and 67 children without psychiatric disorders were matched for age and sex. A MANOVA indicated no significant interaction effects on the results between the sexes in the psychiatric group and the control group for passive vocabulary (F(1,150)=.59, p≥0.05) or for active vocabulary (F(1,150)=.61, p≥0.05). An ANOVA was conducted to determine the differences between the boys and girls for passive and active vocabulary, and the differences between the psychiatric group and the control group for passive and active vocabulary. No significant differences between the boys and girls for passive vocabulary (F(1,150)=1.968, p≥0.05) and active vocabulary (F(1,150)=1.57, p≥0.05) were found. There was a significant difference between the psychiatric and the control group for passive vocabulary (F(1,150)=9.511, p=0.002) and active vocabulary (F(1,150)=16.18, p=0.00009). The study provides support for the presence of language disorders associated with active and passive body awareness in children with psychiatric disorders compared to typically developing children.

Child and adolescent psychiatric genetics

The current status of child and adolescent psychiatric genetics appears promising in light of the initiation of genome-wide association studies (GWAS) for diverse polygenic disorders and the molecular elucidation of monogenic Rett syndrome, for which recent functional studies provide hope for pharmacological treatment strategies. Within the last 50 years, tremendous progress has been made in linking genetic variation to behavioral phenotypes and psychiatric disorders. We summarize the major findings of the Human Genome Project and dwell on largely unsuccessful candidate gene and linkage studies. GWAS for the first time offer the possibility to detect single nucleotide polymorphisms and copy number variants without a priori hypotheses as to their molecular etiology. At the same time it is becoming increasingly clear that very large sample sizes are required in order to enable genome wide significant findings, thus necessitating further large-scaled ascertainment schemes for the successful elucidation of the molecular genetics of childhood and adolescent psychiatric disorders. We conclude by reflecting on different scenarios for future research into the molecular basis of early onset psychiatric disorders. This review represents the introductory article of this special issue of the European Child and Adolescent Psychiatry.

Early vocabulary development in Mandarin (Putonghua) and Cantonese

Parent report instruments adapted from the MacArthur-Bates Communicative Development Inventories (CDI) examined vocabulary development in children aged 0 ; 8 to 2 ; 6 for two Chinese languages, Mandarin (n=1694) and Cantonese (n=1625). Parental reports suggested higher overall scores for Mandarin- than for Cantonese-speaking children from approximately 1 ; 4 onward. Factors relevant to the difference were only-child status, monolingual households and caregiver education. In addition to the comparison of vocabulary scores overall, the development of noun classifiers, grammatical function words common to the two languages, was assessed both in terms of the age and the vocabulary size at which these terms are acquired. Whereas age-based developmental trajectories again showed an advantage for Beijing children, Hong Kong children used classifiers when they had smaller vocabularies, reflecting the higher frequencies and greater precision of classifier use in adult Cantonese. The data speak to the importance of using not just age, but also vocabulary size, as a metric by which the acquisition of particular linguistic elements can be examined across languages.

Predictive validity of Bayley scale in language development of children at 6-36 months

BACKGROUND

The aim of the present study was to investigate the prediction of development among 6-, 18-, and 36-month-old infants on the Bayley Scale of Infant Development (BSID).

METHODS

One hundred infants were assessed using the BSID at 6 months; of these, 70 completed the 18 and 36 month assessment at follow up.

RESULTS

Multivariate regression and structural equation modeling were used to determine predictive validity in the mental and psychomotor developmental scales. Structural equation analysis also confirmed the conceptual scheme of the stability of development from 6 to 36 months for boys. Boys had a steadier overall developmental trajectory compared to girls.

CONCLUSIONS

The validity of BSID was consistent with previous studies. The language spurt in girls, however, from 6 to 18 months affected the stability of the BSID. Thus, the gender difference in language development should be considered in clinical assessment.

African American English: An Overview

This article presents a summary of African-American English (AAE) for the speech-language pathologist. An overview of research on AAE and of the specific linguistic characteristics of AAE is presented. Examples of lexical, phonological, grammatical, and prosodic features of AAE and their implications for assessment are discussed. Linguistic variation within AAE is also described. Educational issues surrounding AAE and teachers' attitudes concerning student use of AAE are considered. The challenges in assessment that AAE presents for the SLP are highlighted along with resources for further information regarding AAE.

Factors affecting vocabulary acquisition at age 2 in children born between 23 and 28 weeks' gestation

Language development is often slower in preterm children compared with their term peers. We investigated factors associated with vocabulary acquisition at 2 years in a cohort of children born at 28 weeks' gestation or less. For children entered into the United Kingdom Oscillation Study, language development was evaluated by using the MacArthur-Bates Communicative Development Inventories score, completed by parents as part of a developmental questionnaire. The effect of demographic, neonatal, socioeconomic factors, growth, and disability were investigated using multifactorial random effects modelling. Questionnaires were returned by 288 participants (148 males, 140 females). The mean number of words vocalized was 42 (SD 29). Multifactorial analysis showed only four factors were significantly associated with vocabulary acquisition. These were: (1) level of disability (mean words: no disability, 45; other disability, 38; severe disability, 30 [severe disability is defined as at least one extreme response in one of the following clinical domains: neuromotor, vision, hearing, communication, or other physical disabilities]; 95% confidence interval [CI] for the difference between no and severe disability 7- 23); (2) sex (39 males, 44 females; 95% CI 0.4-11); (3) length of hospital stay (lower quartile, 47; upper quartile, 38; 95% CI -12 to -4); and (4) weight SD score at 12 months (lower quartile, 39; upper quartile, 44; 95% CI 1-9). There was no significant association between gestational age and vocabulary after multifactorial analysis. There was no significant effect of any socioeconomic factor on vocabulary acquisition. We conclude that clinical factors, particularly indicators of severe morbidity, dominate the correlates of vocabulary acquisition at age 2 in children born very preterm.

Linguistic Features of Japanese Twins at 3 or 4 Years of Age Evaluated by Illinois Test of Psycholinguistic Abilities

In general, twins have delayed language development early in childhood compared with singletons. The purpose of this study was to clarify the overall linguistic features of twins. A Japanese version of the Illinois Test of Psycholinguistic Abilities (ITPA) was administered in 24 twin pairs (aged 3 to 4 years) at their own homes. The overall language abilities of the twins were in the normal range (based on ITPA normative data: mean scale score 36.0 ± 6.0 points), and for the ITPA subtests only, Auditory Reception fell within the range of language disorder (mean scale score 24.9 ± 5.1 points). The findings suggest that in 3- to 4-year-old Japanese twins, overall language abilities are not delayed. However, there may be specific difficulties with auditory reception skills.