Word comprehension mediates the link between gesture and word production: Examining language development in infant siblings of children with autism spectrum disorder

Children's gesture production precedes and predicts language development, but the pathways linking these domains are unclear. It is possible that gesture production assists in children's developing word comprehension, which in turn supports expressive vocabulary acquisition. The present study examines this mediation pathway in a population with variability in early communicative abilities—the younger siblings of children with autism spectrum disorder (ASD; high‐risk infants, HR). Participants included 92 HR infants and 28 infants at low risk (LR) for ASD. A primary caregiver completed the MacArthur‐Bates Communicative Development Inventory (Fenson, et al., 1993) at 12, 14, and 18 months, and HR infants received a diagnostic evaluation for ASD at 36 months. Word comprehension at 14 months mediated the relationship between 12‐month gesture and 18‐month word production in LR and HR infants (ab = 0.263; p < 0.01). For LR infants and HR infants with no diagnosis or language delay, gesture was strongly associated with word comprehension (as = 0.666; 0.646; 0.561; ps < 0.01). However, this relationship did not hold for infants later diagnosed with ASD (a = 0.073; p = 0.840). This finding adds to a growing literature suggesting that children with ASD learn language differently. Furthermore, this study provides an initial step toward testing the developmental pathways by which infants transition from early actions and gestures to expressive language.     

Exploring cortical activation and connectivity in infants with and without familial risk for autism during naturalistic social interactions: A preliminary study

Behavioral signs of Autism Spectrum Disorder (ASD) are typically observable by the second year of life and a reliable diagnosis of ASD is possible by 2 to 3 years of age. Studying infants with familial risk for ASD allows for the investigation of early signs of ASD risk within the first year. Brain abnormalities such as hyper-connectivity within the first year may precede the overt signs of ASD that emerge later in life. In this preliminary study, we use functional near-infrared spectroscopy (fNIRS), an infant-friendly neuroimaging tool that is relatively robust against motion artifacts, to examine functional activation and connectivity during naturalistic social interactions in 9 high-risk (HR; older sibling with ASD) and 6 low-risk (LR; no family history of ASD) infants from 6 to 9 months of age. We obtained two 30-second baseline periods and a 5-minute social interaction period. HR infants showed reduced right and left-hemispheric activation compared to LR infants based on oxy (HbO₂) and deoxy (HHb) signal trends. HR infants also had greater functional connectivity than LR infants during the pre- and post-social periods and showed a drop in connectivity during the social period. Our findings are consistent with previous work suggesting early differences in cortical activation associated with familial risk for ASD, and highlight the promise of fNIRS in evaluating potential markers of ASD risk during naturalistic social contexts.     

Fine motor skill predicts expressive language in infant siblings of children with autism

We investigated whether fine motor and expressive language skills are related in the later‐born siblings of children with autism (heightened‐risk, HR infants) who are at increased risk for language delays. We observed 34 HR infants longitudinally from 12 to 36 months. We used parent report and standardized observation measures to assess fine motor skill from 12 to 24 months in HR infants (Study 1) and its relation to later expressive vocabulary at 36 months in HR infants (Study 2). In Study 1, we also included 25 infants without a family history of autism to serve as a normative comparison group for a parent‐report fine motor measure. We found that HR infants exhibited fine motor delays between 12 and 24 months and expressive vocabulary delays at 36 months. Further, fine motor skill significantly predicted expressive language at 36 months. Fine motor and expressive language skills are related early in development in HR infants, who, as a group, exhibit risk for delays in both. Our findings highlight the importance of considering fine motor skill in children at risk for language impairments and may have implications for early identification of expressive language difficulties.     

Parent‐selected interventions for infants at‐risk for autism spectrum disorders and their affected siblings

Infants with older siblings having Autism Spectrum Disorders (ASD) are at genetically increased risk for showing characteristics of ASD in the first 2 years of life. Parents, who already have at least one child with ASD, may closely monitor their later born children and implement interventions as soon as the children begin to show what the parents believe is aberrant behavior or development that may be early stages of ASD. To date, no study has examined the number and types of services and interventions these parents access for their at‐risk infants. Using a Service and Intervention Questionnaire developed for this study, we interviewed 23 parents involved in a larger prospective study of genetically at‐risk infants who reported developmental and/or behavior problems in their at‐risk infants. Parents reported utilizing a mean of 1.83 and 7.26 services and/or interventions for their at‐risk infants and older children with ASD, respectively. Two‐thirds of the interventions received by the infants were also given to their older affected siblings. The interventions included empirically validated approaches (e.g., early intensive behavioral intervention), professional services (speech–language therapy, occupational therapy), and non‐validated treatments (e.g., diet and vitamin therapies). Overall, 81 non‐validated and 18 validated interventions were used. On a Likert‐type rating scale, parents reported being involved and satisfied with what they generally thought were effective services. They felt more involved and satisfied with ABA, and felt it was more effective than non‐validated interventions. The findings suggest that parents with infants at‐risk for ASD and an older affected child will access a variety of autism services for both children, but the parents will implement primarily non‐validated interventions. Parent education is recommended to help parents make informed treatment decisions for their children. Copyright © 2009 John Wiley & Sons, Ltd.     

Differences in caregiver behaviors of infants at-risk for autism and typically developing infants from 9 to 15 months of age

During an object sharing paradigm, we compared infant-caregiver interactions between two groups: i) infants at high-risk (HR) for being diagnosed with Autism Spectrum Disorder (ASD) and ii) low-risk (LR) infants, observed at 9, 12, and 15 months of age. 16 HR infants (14 infants with an older sibling diagnosed with ASD and 2 preterm infants that received a diagnosis of ASD at 2 years) and 16 LR infants (typically developing infants without older siblings diagnosed with ASD) were included in the study. At each visit, infants played with objects in the presence of their caregivers as crawlers or walkers. Previously, we found that HR infants are less likely to share their object play with caregivers at walker ages. The present study found that caregivers of HR infants used greater directive bids including being more proximal to infants and using greater verbal and non-verbal bids to sustain their infant’s attention and to ensure their compliance during the task compared to caregivers of LR infants. Our study emphasizes the bidirectional and dynamic nature of infant-caregiver interactions. Our findings have implications for caregiver training programs that teach parents appropriate strategies to promote early social communication skills in at-risk infants.     

Attachment security differs by later autism spectrum disorder: A prospective study

Although difficulties with social relationships are key to autism spectrum disorder (ASD), no previous study has examined infant attachment security prior to ASD diagnosis. We prospectively assessed attachment security at 15 months in high‐risk infants with later ASD (high‐risk/ASD, n = 16), high‐risk infants without later ASD (high‐risk/no‐ASD, n = 40), and low‐risk infants without later ASD (low‐risk/no‐ASD, n = 39) using the Strange Situation Procedure. High‐risk/ASD infants were disproportionately more likely to be classified as insecure (versus secure) and more likely to be classified as insecure‐resistant (versus secure or avoidant) than high‐risk/no‐ASD and low‐risk/no‐ASD infants. High‐risk infants with insecure‐resistant attachments were over nine times more likely to receive an ASD diagnosis than high‐risk infants with secure attachments. Insecure‐resistant attachment in high‐risk infants suggests a propensity toward negative affect with the parent in conditions of stress. Insecure‐resistant attachment may prove useful as a potential early index of propensity toward ASD diagnosis in high‐risk siblings, while insecure‐resistant attachment in the context of emergent autism may contribute to difficulties experienced by children with ASD and their families.     

Splenium development and early spoken language in human infants

The association between developmental trajectories of language‐related white matter fiber pathways from 6 to 24 months of age and individual differences in language production at 24 months of age was investigated. The splenium of the corpus callosum, a fiber pathway projecting through the posterior hub of the default mode network to occipital visual areas, was examined as well as pathways implicated in language function in the mature brain, including the arcuate fasciculi, uncinate fasciculi, and inferior longitudinal fasciculi. The hypothesis that the development of neural circuitry supporting domain‐general orienting skills would relate to later language performance was tested in a large sample of typically developing infants. The present study included 77 infants with diffusion weighted MRI scans at 6, 12 and 24 months and language assessment at 24 months. The rate of change in splenium development varied significantly as a function of language production, such that children with greater change in fractional anisotropy (FA) from 6 to 24 months produced more words at 24 months. Contrary to findings from older children and adults, significant associations between language production and FA in the arcuate, uncinate, or left inferior longitudinal fasciculi were not observed. The current study highlights the importance of tracing brain development trajectories from infancy to fully elucidate emerging brain–behavior associations while also emphasizing the role of the splenium as a key node in the structural network that supports the acquisition of spoken language.     

Effects of maternal postpartum depression in a well‐resourced sample: Early concurrent and long‐term effects on infant cognitive,language, and motor development

This study examined early and long‐term effects of maternal postpartum depression on cognitive, language, and motor development in infants of clinically depressed mothers. Participants were 83 mothers and their full‐term born children from the urban region of Copenhagen, Denmark. Of this group, 28 mothers were diagnosed with postnatal depression three to four months postpartum in a diagnostic interview. Cognitive, language, and motor development was assessed with the Bayley Scales of Infant and Toddler Development third edition, when the infants were 4 and 13 months of age. We found that maternal postpartum depression was associated with poorer cognitive development at infant age four months, the effect size being large (Cohen's d = 0.8) and with similar effects for boys and girls. At 13 months of age infants of clinical mothers did not differ from infants of non‐clinical mothers. At this time most (79%) of the clinical mothers were no longer, or not again, depressed. These results may indicate that maternal depression can have an acute, concurrent effect on infant cognitive development as early as at four months postpartum. At the same time, in the absence of other risk factors, this effect may not be enduring. The main weaknesses of the study include the relatively small sample size and that depression scores were only available for 35 of the non‐clinical mothers at 13 months.     

Developmental change in the neuropsychological functioning of very low birth weight infants

Research on very low birth weight (VLBW) infants has not carefully evaluated developmental patterns of neurological and neuropsychological functioning across time. This study reports on a broad range of developmental outcomes for VLBW infants of low (LR, n = 116) and high (HR, n = 84) medical risk compared to full term infants (FT, n = 120) across 6, 12, and 24 months of age. While low risk infants showed initial delays in most areas, faster rates of change in motor and neurological development resulted in catch-up by 2 years of age as compared to the FT infants. The lack of acceleration in development of mental skills demonstrates a persistent lag in this area. In contrast, HR infants showed initial delays in all areas as compared to both LR and FT infants with slower rates of change in mental and expressive language skills. Although faster rates of change were evident for HR infants in motor, neurological, and receptive language skills, scores in these areas remain lower than those for the LR and FT infants. The absence of accelerated rates of development for certain VLBW infants has implications for prognosis and patient access to early intervention services.     

Behavioural markers for autism in infancy: Scores on the Autism Observational Scale for Infants in a prospective study of at-risk siblings

We investigated early behavioural markers of autism spectrum disorder (ASD) using the Autism Observational Scale for Infants (AOSI) in a prospective familial high-risk (HR) sample of infant siblings (N = 54) and low-risk (LR) controls (N = 50). The AOSI was completed at 7 and 14 month infant visits and children were seen again at age 24 and 36 months. Diagnostic outcome of ASD (HR-ASD) versus no ASD (HR-No ASD) was determined for the HR sample at the latter timepoint. The HR group scored higher than the LR group at 7 months and marginally but non-significantly higher than the LR group at 14 months, although these differences did not remain when verbal and nonverbal developmental level were covaried. The HR-ASD outcome group had higher AOSI scores than the LR group at 14 months but not 7 months, even when developmental level was taken into account. The HR-No ASD outcome group had scores intermediate between the HR-ASD and LR groups. At both timepoints a few individual items were higher in the HR-ASD and HR-No ASD outcome groups compared to the LR group and these included both social (e.g. orienting to name) and non-social (e.g. visual tracking) behaviours. AOSI scores at 14 months but not at 7 months were moderately correlated with later scores on the autism diagnostic observation schedule (ADOS) suggesting continuity of autistic-like behavioural atypicality but only from the second and not first year of life. The scores of HR siblings who did not go on to have ASD were intermediate between the HR-ASD outcome and LR groups, consistent with the notion of a broader autism phenotype.     

Additive effects of social and non‐social attention during infancy relate to later autism spectrum disorder

Emerging findings from studies with infants at familial high risk for autism spectrum disorder (ASD), owing to an older sibling with a diagnosis, suggest that those who go on to develop ASD show early impairments in the processing of stimuli with both social and non‐social content. Although ASD is defined by social‐communication impairments and restricted and repetitive behaviours, the majority of cognitive theories of ASD posit a single underlying factor, which over development has secondary effects across domains. This is the first high‐risk study to statistically differentiate theoretical models of the development of ASD in high‐risk siblings using multiple risk factors. We examined the prediction of ASD outcome by attention to social and non‐social stimuli: gaze following and attentional disengagement assessed at 13 months in low‐risk controls and high‐risk ASD infants (who were subsequently diagnosed with ASD at 3 years). When included in the same regression model, these 13‐month measures independently predicted ASD outcome at 3 years of age. The data were best described by an additive model, suggesting that non‐social attention, disengagement, and social attention as evidenced by gaze following, have a cumulative impact on ASD risk. These data argue against cognitive theories of ASD which propose that a single underlying factor has cascading effects across early development leading to an ASD outcome, and support multiple impairment models of ASD that are more consistent with recent genetic and neurobiological evidence.     

The over‐pruning hypothesis of autism

This article outlines the over‐pruning hypothesis of autism. The hypothesis originates in a neurocomputational model of the regressive sub‐type (Thomas, Knowland & Karmiloff‐Smith, 2011a, 2011b). Here we develop a more general version of the over‐pruning hypothesis to address heterogeneity in the timing of manifestation of ASD, including new computer simulations which reconcile the different observed developmental trajectories (early onset, late onset, regression) via a single underlying atypical mechanism; and which show how unaffected siblings of individuals with ASD may differ from controls either by inheriting a milder version of the pathological mechanism or by co‐inheriting the risk factors without the pathological mechanism. The proposed atypical mechanism involves overly aggressive synaptic pruning in infancy and early childhood, an exaggeration of a normal phase of brain development. We show how the hypothesis generates novel predictions that differ from existing theories of ASD including that (1) the first few months of development in ASD will be indistinguishable from typical, and (2) the earliest atypicalities in ASD will be sensory and motor rather than social. Both predictions gain cautious support from emerging longitudinal studies of infants at‐risk of ASD. We review evidence consistent with the over‐pruning hypothesis, its relation to other current theories (including C. Frith's under‐pruning proposal; C. Frith, 2003, 2004), as well as inconsistent data and current limitations. The hypothesis situates causal accounts of ASD within a framework of protective and risk factors (Newschaffer et al., 2012); clarifies different versions of the broader autism phenotype (i.e. the implication of observed similarities between individuals with autism and their family members); and integrates data from multiple disciplines, including behavioural studies, neuroscience studies, genetics, and intervention studies.     

Multifactorial pathways facilitate resilience among kindergarteners at risk for dyslexia: A longitudinal behavioral and neuroimaging study

Recent efforts have focused on screening methods to identify children at risk for dyslexia as early as preschool/kindergarten. Unfortunately, while low sensitivity leads to under‐identification of at‐risk children, low specificity can lead to over‐identification, resulting in inaccurate allocation of limited educational resources. The present study focused on children identified as at‐risk in kindergarten who do not subsequently develop poor reading skills to specify factors associated with better reading outcomes among at‐risk children. Early screening was conducted in kindergarten and a subset of children was tracked longitudinally until second grade. Potential protective factors were evaluated at cognitive‐linguistic, environmental, and neural levels. Relative to at‐risk kindergarteners with subsequent poor reading, those with typical reading outcomes were characterized by significantly higher socioeconomic status (SES), speech production accuracy, and structural organization of the posterior right‐hemispheric superior longitudinal fasciculus (SLF). A positive association between structural organization of the right SLF and subsequent decoding skills was found to be specific to at‐risk children and not observed among typical controls. Among at‐risk children, several kindergarten‐age factors were found to significantly contribute to the prediction of subsequent decoding skills: white matter organization in the posterior right SLF, age, gender, SES, and phonological awareness. These findings suggest that putative compensatory mechanisms are already present by the start of kindergarten. The right SLF, in conjunction with the cognitive‐linguistic and socioeconomic factors identified, may play an important role in facilitating reading development among at‐risk children. This study has important implications for approaches to early screening, and assessment strategies for at‐risk children.     

Developmental Changes in Pretend Play from 22- to 34-Months in Younger Siblings of Children with Autism Spectrum Disorder

Developmental trajectories of children’s pretend play and social engagement, as well as parent sensitivity and stimulation, were examined in toddlers with an older sibling with autism spectrum disorder (ASD, high risk; HR) and toddlers with typically-developing older siblings (low risk; LR). Children (N = 168, 97 boys, 71 girls) were observed at 22, 28, and 34 months during free play with a parent and elicited pretend play with an examiner. At 28 and 34 months, children were asked to imagine the consequences of actions pantomimed by the examiner on a pretend transformation task. At 36 months children were assessed for ASD, yielding 3 groups for comparison: HR children with ASD, HR children without ASD (HR-noASD), and LR children. Children in all 3 groups showed developmental changes, engaging in more bouts of pretend play and obtaining higher scores on the elicited pretend and transformation tasks with age, but children with ASD lagged behind the other 2 groups on most measures. Children with ASD were also less engaged with their parents or the examiner during play interactions than either LR or HR-noASD children, with minimal developmental change evident. Parents, regardless of group, were highly engaged with their children, but parents of HR-noASD children received somewhat higher ratings on stimulation than parents of LR children. Most group differences were not accounted for by cognitive functioning. Instead, lower social engagement appears to be an important correlate of less advanced pretend skills, with implications for understanding the early development of children with ASD and for early intervention.     

The relationship between biological and psychosocial risk factors and resting‐state functional connectivity in 2‐month‐old Bangladeshi infants: A feasibility and pilot study

Childhood poverty has been associated with structural and functional alterations in the developing brain. However, poverty does not alter brain development directly, but acts through associated biological or psychosocial risk factors (e.g. malnutrition, family conflict). Yet few studies have investigated risk factors in the context of infant neurodevelopment, and none have done so in low‐resource settings such as Bangladesh, where children are exposed to multiple, severe biological and psychosocial hazards. In this feasibility and pilot study, usable resting‐state fMRI data were acquired in infants from extremely poor (n = 16) and (relatively) more affluent (n = 16) families in Dhaka, Bangladesh. Whole‐brain intrinsic functional connectivity (iFC) was estimated using bilateral seeds in the amygdala, where iFC has shown susceptibility to early life stress, and in sensory areas, which have exhibited less susceptibility to early life hazards. Biological and psychosocial risk factors were examined for associations with iFC. Three resting‐state networks were identified in within‐group brain maps: medial temporal/striatal, visual, and auditory networks. Infants from extremely poor families compared with those from more affluent families exhibited greater (i.e. less negative) iFC in precuneus for amygdala seeds; however, no group differences in iFC were observed for sensory area seeds. Height‐for‐age, a proxy for malnutrition/infection, was not associated with amygdala/precuneus iFC, whereas prenatal family conflict was positively correlated. Findings suggest that it is feasible to conduct infant fMRI studies in low‐resource settings. Challenges and practical steps for successful implementations are discussed.     

Face engagement during infancy predicts later face recognition ability in younger siblings of children with autism

Face recognition difficulties are frequently documented in children with autism spectrum disorders (ASD). It has been hypothesized that these difficulties result from a reduced interest in faces early in life, leading to decreased cortical specialization and atypical development of the neural circuitry for face processing. However, a recent study by our lab demonstrated that infants at increased familial risk for ASD, irrespective of their diagnostic status at 3 years, exhibit a clear orienting response to faces. The present study was conducted as a follow‐up on the same cohort to investigate how measures of early engagement with faces relate to face‐processing abilities later in life. We also investigated whether face recognition difficulties are specifically related to an ASD diagnosis, or whether they are present at a higher rate in all those at familial risk. At 3 years we found a reduced ability to recognize unfamiliar faces in the high‐risk group that was not specific to those children who received an ASD diagnosis, consistent with face recognition difficulties being an endophenotype of the disorder. Furthermore, we found that longer looking at faces at 7 months was associated with poorer performance on the face recognition task at 3 years in the high‐risk group. These findings suggest that longer looking at faces in infants at risk for ASD might reflect early face‐processing difficulties and predicts difficulties with recognizing faces later in life.     

Infant motor skill predicts later expressive language and autism spectrum disorder diagnosis

Motor difficulties may be an early Autism Spectrum Disorder (ASD) risk indicator and may predict subsequent expressive language skills. Further understanding of motor functioning in the first year of life in children with ASD is needed. We examined motor skills in 6-month-olds (n = 140) at high and low familial risk for ASD using the Peabody Developmental Motor Scales (Grasping, Visual-Motor Integration, and Stationary subscales). In Study 1, motor skill at 6 months predicted ASD status at 24–36 months; ASD was associated with poorer infant motor skills. In Study 2, motor skill at 6 months predicted expressive language at 30 and 36 months. Findings provide evidence that vulnerability in motor function early in development is present in ASD. Findings highlight the importance of developmental monitoring in high-risk infants and possible cascading effects of early disruption in motor development.     

Adaptation of the Mullen Scales of Early Learning for use among infants aged 5‐ to 24‐months in rural Gambia

Infants in low‐resource settings are at heightened risk for compromised cognitive development due to a multitude of environmental insults in their surroundings. However, the onset of adverse outcomes and trajectory of cognitive development in these settings is not well understood. The aims of the present study were to adapt the Mullen Scales of Early Learning (MSEL) for use with infants in a rural area of The Gambia, to examine cognitive development in the first 24‐months of life and to assess the association between cognitive performance and physical growth. In Phase 1 of this study, the adapted MSEL was tested on 52 infants aged 9‐ to 24‐months (some of whom were tested longitudinally at two time points). Further optimization and training were undertaken and Phase 2 of the study was conducted, where the original measures were administered to 119 newly recruited infants aged 5‐ to 24‐months. Infant length, weight and head circumference were measured concurrently in both phases. Participants from both phases were split into age categories of 5–9 m (N = 32), 10–14 m (N = 92), 15–19 m (N = 53) and 20–24 m (N = 43) and performance was compared across age groups. From the ages of 10–14 m, Gambian infants obtained lower MSEL scores than US norms. Performance decreased with age and was lowest in the 20–24 m old group. Differential onsets of reduced performance were observed in the individual MSEL domains, with declines in visual perception and motor performance detected as early as at 10–14 months, while reduced language scores became evident after 15–19 months of age. Performance on the MSEL was significantly associated with measures of growth.     

Enhanced gaze‐following behavior in Deaf infants of Deaf parents

Gaze following plays a role in parent–infant communication and is a key mechanism by which infants acquire information about the world from social input. Gaze following in Deaf infants has been understudied. Twelve Deaf infants of Deaf parents (DoD) who had native exposure to American Sign Language (ASL) were gender‐matched and age‐matched (±7 days) to 60 spoken‐language hearing control infants. Results showed that the DoD infants had significantly higher gaze‐following scores than the hearing infants. We hypothesize that in the absence of auditory input, and with support from ASL‐fluent Deaf parents, infants become attuned to visual‐communicative signals from other people, which engenders increased gaze following. These findings underscore the need to revise the ‘deficit model’ of deafness. Deaf infants immersed in natural sign language from birth are better at understanding the signals and identifying the referential meaning of adults’ gaze behavior compared to hearing infants not exposed to sign language. Broader implications for theories of social‐cognitive development are discussed. A video abstract of this article can be viewed at https://youtu.be/QXCDK_CUmAI     

Implicit meaning in 18‐month‐old toddlers

A substantial body of evidence demonstrates that infants understand the meaning of spoken words from as early as 6 months. Yet little is known about their ability to do so in the absence of any visual referent, which would offer diagnostic evidence for an adult‐like, symbolic interpretation of words and their use in language mediated thought. We used the head‐turn preference procedure to examine whether infants can generate implicit meanings from word forms alone as early as 18 months of age, and whether they are sensitive to meaningful relationships between words. In one condition, toddlers were presented with lists of words taken from the same taxonomic category (e.g. animals or body parts). In a second condition, words taken from two other categories (e.g. clothes and food items) were interleaved within the same list. Listening times were found to be longer in the related‐category condition than in the mixed‐category condition, suggesting that infants extract the meaning of spoken words and are sensitive to the semantic relatedness between these words. Our results show that infants have begun to construct the rudiments of a semantic system based on taxonomic relations even before they enter a period of accelerated vocabulary growth.