Infant Siblings Research Articles

Prospective Interrelation Between Sensory Sensitivity and Fine Motor Skills During the First 18 Months Predicts Later Autistic Features.

Sensory features are included in the diagnostic criteria of autism and atypical sensory responsiveness may produce "cascading effects" on later development. Similarly, autistic individuals often struggle with motor coordination and early delays in the motor domain appear to be linked to later development. However, the longitudinal interrelation between early sensory profiles and motor features on later socio-communicative skills remains to be defined. This study aimed to investigate whether sensory sensitivity impacts fine motor abilities and vice versa from 12 to 18 months of age and to examine how sensory-motor interplay would be associated with later autistic traits at 24-36 months of age. The sample included 118 infant siblings of autistic children recruited at 12 months of age. Sensory sensitivity and eye-hand coordination were assessed at 12 and 18 months of age and autistic traits were evaluated at 24-36 months of age. Cross-lagged panel analysis revealed significant within-domain effects for sensory sensitivity and eye-hand coordination from 12 to 18 months. Furthermore, a significant association between these two domains on later autistic traits was found. In analyzing the longitudinal bidirectional relationship, we found that lower eye-hand coordination skills at 12 months predicted later sensory sensitivity at 18 months, and in turn, social communication skills at 24-36 months. The present study offers new empirical evidence supporting the potential clinical value of including sensory and motor measures besides social communication skills within early autism surveillance programs.

Preliminary isotopic assessment of weaning in bonobos shows evidence for extended nursing, sibling competition and invested first-time mothers.

Although considered a hallmark in early ontogeny, weaning from breastmilk is difficult to monitor in wild primates and weaning ages remain unknown for wild bonobos (Pan Paniscus). Here, we calculated inter-birth intervals from demographic data and measured the isotopic offsets (Δ15N and Δ13C) between mother (n = 17) and offspring (n = 28) fecal sample pairs (n = 131, total n = 246) in the LuiKotale bonobos to assess nutritional weaning for the first time. We tested the effects of infant age, female parity, and sibling competition on Δ15N and Δ13C values. We found bonobo inter-birth intervals ranging from 2.2 to 7.3 years (x̄ = 4.7 ± 1.3 years) at LuiKotale. The Δ15N and Δ13C values suggested nutritional weaning on average by 6.6 and 7.0 years of age respectively, considerably exceeding weaning ages reported for chimpanzees (P. troglodytes) using the same approach. Our Δ13C data suggested that the number of offspring present affected nursing, with first-time mothers nursing more and possibly longer. The Δ15N and Δ13C values decreased with the arrival of the next sibling, suggesting sibling competition reduces milk access. Nevertheless, offspring may continue nursing 2.5-3 years after the birth of the next sibling, corresponding well with observations on low infant mortality. In conclusion, bonobo mothers provide remarkably enduring materna l support in the form of nursing concurrently to several offspring.

Familial Recurrence of Autism: Updates From the Baby Siblings Research Consortium.

Autism spectrum disorder (ASD) is estimated to be ∼10 times higher in children with versus without an autistic sibling in population-based studies. Prospective studies of infant siblings have revealed even higher familial recurrence rates. In the current prospective longitudinal study, we provide updated estimates of familial ASD recurrence using a multinational database of infants with older autistic siblings. Data were collated across 18 sites of the Baby Siblings Research Consortium, an international network studying the earliest manifestations of ASD. A total of 1605 infants with an older autistic sibling were followed from early in life to 3 years, when they were classified as ASD or non-ASD. Hierarchical generalized linear modeling, with site as a random effect, was used to examine predictors of recurrence in families and calculate likelihood ratios. A total of 20.2% of siblings developed ASD, which is not significantly higher than the previously reported rate of 18.7%. Male infant sex and >1 older affected sibling were significant predictors of familial recurrence. Proband sex also influenced recurrence rates, with siblings of female probands significantly more likely to develop ASD than siblings of male probands. Race and maternal education were also associated with recurrence in families. The familial recurrence rate of ASD, as measured in infant sibling studies, has not changed appreciably since previous estimates were made in 2011. Younger siblings of autistic children, particularly those who are male, have an affected female sibling, multiple affected siblings, or are impacted by social inequities, should be closely monitored and promptly referred for diagnostic evaluation.

Sensitivity to temporal synchrony and selective attention in audiovisual speech in infants at elevated likelihood for autism: A preliminary longitudinal study

Autism Spectrum Disorder is a highly heritable condition characterized by sociocommunicative difficulties, frequently entailing language atypicalities that extend to infants with a familial history of autism. The developmental mechanisms underlying these difficulties remain unknown. Detecting temporal synchrony between the lip movements and the auditory speech of a talking face and selectively attending to the mouth support typical early language acquisition. This preliminary eye-tracking study investigated whether these two fundamental mechanisms atypically function in infant siblings. We longitudinally tracked the trajectories of infants at elevated and low-likelihood for autism in these two abilities at 4, 8, and 12 months (n = 29). We presented two talking faces (synchronous and asynchronous) while recording infants’ gaze to the talker’s eyes and mouth. We found that infants detected temporal asynchronies in talking faces at 12 months regardless of group. However, compared to their typically developing peers, infants with an elevated likelihood of autism showed reduced attention to the mouth at the end of the first year and no variations in their interest to this area across time. Our findings provide preliminary evidence on a potentially atypical trajectory of reduced mouth-looking in audiovisual speech during the first year in infant siblings, with potential cascading consequences for language development, thus contributing to domain-general accounts of emerging autism.

Homozygous TNNI3 frameshift variant in a consanguineous family with lethal infantile dilated cardiomyopathy.

Dilated cardiomyopathy (DCM) is characterized by dilatation of the left ventricle, systolic dysfunction, and normal or reduced thickness of the left ventricular wall. It is a leading cause of heart failure and cardiac death at a young age. Cases with neonatal onset DCM were correlated with severe clinical presentation and poor prognosis. A monogenic molecular etiology accounts for nearly half of cases. Here, we report a family with three deceased offspring at the age of 1 year old. The autopsy of the first deceased infant revealed a DCM. The second infant presented a DCM phenotype with a severely reduced Left Ventricular Ejection Fraction (LVEF) of 10%. Similarly, the third infant showed a severe DCM phenotype with LVEF of 30% as well, in addition to eccentric mitral insufficiency. Exome sequencing was performed for the trio (the second deceased infant and her parents). Data analysis following the autosomal dominant and recessive patterns of inheritance was carried out along with a mitochondrial pathways-based analysis. We identified a homozygous frameshift variant in the TNNI3 gene (c.204delG; p.(Arg69AlafsTer8)). This variant has been recently reported in the ClinVar database in association with cardiac phenotypes as pathogenic or likely pathogenic and classified as pathogenic according to ACMG. Genetic counseling was provided for the family and a prenatal diagnosis of choronic villus was proposed in the absence of pre-implantation genetic diagnosis possibilities. Our study expands the case series of early-onset DCM patients with a protein-truncating variant in the TNNI3 gene by reporting three affected infant siblings.

Cost-effectiveness analysis of pertussis booster vaccination for adolescents in Japan

IntroductionIn Japan, the introduction of a fifth diphtheria–tetanus–acellular pertussis (DTaP) vaccination has been considered, and adolescents aged 11–12 years old who are currently receiving the diphtheria–tetanus (DT) vaccine are one candidate group. We analyze the cost-effectiveness of replacing the DT vaccine with the DTaP vaccine for 11-year-old adolescents and investigate the indirect effect of vaccinated adolescents on unvaccinated infant siblings. We undertake two analyses using high- and low-morbidity pertussis cases, and based on the results, present suggestions for pertussis prevention in the post-COVID-19 pandemic era. MethodWe used the number of pertussis cases in 2019 as the high-morbidity case and the average number of cases in 2020–2021 as the low-morbidity case, and evaluated the incremental cost-effectiveness ratio (ICER) of the DTaP strategy to the DT strategy based on quality-adjusted life years (QALYs). The economic model contained adolescent and infant sub-models. The indirect effect for infants was considered as the probability of unvaccinated infants avoiding pertussis infection from their vaccinated siblings. ResultsThe ICER from the payers’ perspective was Japanese yen (JPY) 4,254,515 per QALY gained in the high-morbidity case and JPY 62,546,776 per QALY gained in the low-morbidity case. The sensitivity analysis showed that the utility of pertussis had the greatest impact on the ICER, with a 60.58% and 0% probability that the ICER was less than JPY 5 million per QALY gained in the high-morbidity case and low-morbidity case, respectively. ConclusionThe cost-effectiveness of replacing the DT vaccine with the DTaP vaccine is affected by the level of pertussis morbidity, with the ICER becoming more favorable in the high-morbidity case. The indirect effect has little impact on the ICER. Thus, policy-makers should continue to monitor the pertussis epidemic in the post-COVID-19 era, and determine the need to introduce a booster based on perceived trends.

White matter development and language abilities during infancy in autism spectrum disorder.

White matter (WM) fiber tract differences are present in autism spectrum disorder (ASD) and could be important markers of behavior. One of the earliest phenotypic differences in ASD are language atypicalities. Although language has been linked to WM in typical development, no work has evaluated this association in early ASD. Participants came from the Infant Brain Imaging Study and included 321 infant siblings of children with ASD at high likelihood (HL) for developing ASD; 70 HL infants were later diagnosed with ASD (HL-ASD), and 251 HL infants were not diagnosed with ASD (HL-Neg). A control sample of 140 low likelihood infants not diagnosed with ASD (LL-Neg) were also included. Infants contributed expressive language, receptive language, and diffusion tensor imaging data at 6-, 12-, and 24 months. Mixed effects regression models were conducted to evaluate associations between WM and language trajectories. Trajectories of microstructural changes in the right arcuate fasciculus were associated with expressive language development. HL-ASD infants demonstrated a different developmental pattern compared to the HL-Neg and LL-Neg groups, wherein the HL-ASD group exhibited a positive association between WM fractional anisotropy and language whereas HL-Neg and LL-Neg groups showed weak or no association. No other fiber tracts demonstrated significant associations with language. In conclusion, results indicated arcuate fasciculus WM is linked to language in early toddlerhood for autistic toddlers, with the strongest associations emerging around 24 months. To our knowledge, this is the first study to evaluate associations between language and WM development during the pre-symptomatic period in ASD.

Autism Observation Scale for Infants: Systematic Review and Meta-Analysis in Samples at Increased Likelihood of Autism Spectrum Disorders

AbstractThe Autism Observation Scale for Infants (AOSI) is being applied to non infant sibling populations. Assessment of the tool’s utility across increased likelihood (IL) populations is therefore needed. A systematic review and meta-analysis was conducted on 17 studies identified from six databases. The AOSI has been used in four IL contexts: infant siblings, infants with Fragile X Syndrome, Tuberous Sclerosis Complex, and Down Syndrome. There were three main findings: (1) five studies report classification data though no consistent approach was used; (2) group differences between IL-ASD, IL non-ASD, and controls started at 12-months; and (3) large effect sizes between IL-ASD and control samples was identified. Utility of the AOSI to identify early signs of ASD in IL populations was demonstrated.

Utility of the Language Use Inventory in Young Children at Elevated Likelihood of Autism.

The aims of this study were (a) to evaluate the convergent validity of the Language Use Inventory (LUI) with measures of autism spectrum disorder (ASD) symptoms, language, and social skills and (b) to assess discriminant validity of the LUI with measures of nonlanguage skills, including daily living skills and motor development. This study sample included participants from a longitudinal study (n = 239) of infant siblings with elevated familial likelihood of ASD and lower familial likelihood. Assessment measures completed at 36 months included the LUI, the Autism Diagnostic Observation Schedule-Second Edition (ADOS-2), the Mullen Scales of Early Learning, and the Vineland Adaptive Behavior Scales-Second Edition. Bivariate Pearson correlations were estimated between ADOS-2 comparison scores and four language and social skills measures. Additional correlations were estimated between LUI total scores and standard scores from nonlanguage measures. A series of Fisher's Z transformations were applied to evaluate whether bivariate correlations were significantly different. All four language and social skill measures were moderately to strongly associated with each other and ASD symptom severity scores. The correlation between ADOS-2 comparison scores and LUI total scores was significantly stronger than ADOS-2 correlations with all other measures. Our findings provide support for the LUI as a feasible, pragmatic language-targeted instrument for inclusion in early developmental evaluations prompted by language concerns. Administration of the LUI may accelerate earlier referral for a comprehensive assessment of ASD symptoms. Given the high correlation with ADOS-2 scores, an LUI total score in a clinical range of concern may encourage a clinician to refer families for a full diagnostic evaluation of ASD.

Comparing the effects of infant maternal and sibling separation on adolescent behavior in rats (Rattus norvegicus).

Maternal separation in early life has been observed to have lasting, detrimental effects that impair personal and social development and can persist into adulthood. Maternal separation during infancy can be most detrimental during adolescence, leading to long-term adverse effects on development and social behavior. This research study compared the effects of sibling and maternal separation in infancy on anxiety, sociability, or memory later in adolescence (postnatal day, PND, 50-58) in male and female Long-Evans Rats (Rattus norvegicus). Rat pups were semi-randomly assigned into eight conditions for daily isolation (PND 1-14). The groups were separated by the duration of isolation between 15 minutes (control group) or 180 minutes (experimental group) and the sex of the rat. They were also separated by comfort conditions with the dam present in an adjoining cage versus not present and siblings present or not present during isolation. The result was a 2 (15-min vs. 180-min) x 2 (dam vs. no dam) x 2 (single vs. grouped) x 2 (male vs. female) design. Once pups had reached adolescence (PND 50), researchers tested for differences in anxiety, activity, and social behavior using elevated plus-maze, open field habituation, a three-chamber social interaction, and a social discrimination task. Results indicate that longer isolation was more stressful and caused lower body weight. The female rats showed more anxious behavior in the open field but only if they were in the shorter isolation group. Social interaction showed that the rats isolated with the dam had different effects of isolation. In males, shorter isolation with the dam increased sociability but decreased sociability in females. These complicated findings may be due to the effects of inoculation, which describes how moderate stress combined with comfort may produce adaptation or immunity to stress and affect males and females differently.

EPCO-44. RHABDOID TUMOR PREDISPOSITION SYNDROME DUE TO A GERMLINE SMARCB1 MUTATION IN TWO INFANT SIBLINGS

Abstract INTRODUCTION Rhabdoid tumors (RTs) are highly aggressive malignancies caused by a loss–of–function mutation in the SMARCB1 tumor suppressor gene on chromosome 22 that makes up the SW1/SNF chromatin remodeling complex involved in gene transcription. In rhabdoid tumor predisposition syndrome (RTPS), a biallelic germline SMARCB1 mutation markedly increases the risk of affected individuals developing early, aggressive, and rapidly progressing RTs, most commonly in the CNS, referred to as atypical teratoid rhabdoid tumors (AT/RT), and the kidneys, but oftentimes presents with synchronous lesions. In this case series, we present a family affected by RTPS with a recurrence of AT/RT in two infant siblings with the same germline SMARCB1 mutation. CASE SERIES DESCRIPTION An 8-month-old female was brought to the emergency department for 3 months of vomiting, developmental regression, and CN VI palsy. Brain imaging revealed a posterior fossa mass, acquired obstructive hydrocephalus, and spinal metastasis. Four years later, her 3-month-old sister was also brought in for evaluation for 2 months of vomiting, irritability, increasing head circumference, and vertical gaze palsy. Her brain imaging similarly showed a posterior fossa mass and acquired obstructive hydrocephalus, but no metastasis. Both siblings underwent subtotal tumor resections and ventriculoperitoneal shunt placement followed by chemotherapy. While on active treatment, they experienced rapid disease progression and ultimately succumbed to their illness. Genetic testing on the family identified the same in-frame deletion in the SNF5 homology domain of SMARCB1 and loss of heterozygosity of chromosome 22 in the two sisters; their mother was found to be a carrier. CONCLUSION This case series describes a family affected by RTPS, demonstrating the risk of familial recurrence in SMARCB1 germline mutations and emphasizing the need for genetic testing and counseling for these families should they wish to have additional children.

Infant Communication Across the Transition to Walking: Developmental Cascades Among Infant Siblings of Children with Autism.

New motor skills can shape how infants communicate with their caregivers. For example, learning to walk allows infants to move faster and farther than they previously could, in turn allowing them to approach their caregivers more frequently to gesture or vocalize. Does the link between walking and communication differ for infants later diagnosed with autism spectrum disorder (ASD), whose communicative and motor development differs from their neurotypically developing peers? We prospectively followed two groups of infants longitudinally during the transition from crawling to walking: (1) N = 25 infants with no family history of ASD; and (2) N = 91 infants with an older sibling with ASD. Fifteen infants were later diagnosed with ASD, and 26 infants showed a language delay (but did not receive an ASD diagnosis). After learning to walk, infants without ASD or language delay showed considerable changes in their communication: They gestured more frequently, and increasingly coordinated their gestures and vocalizations with locomotion (e.g., by approaching a caregiver and showing a toy). Infants with language delay showed similar but attenuated growth in their communication. However, infants later diagnosed with ASD did not display enhanced communication after they began to walk.

Brief Report: Single and Repeat Screening with the Modified Checklist for Autism in Toddlers-Revised in Young Children at Higher Likelihood for Autism Spectrum Disorder.

To compare the utility of single versus repeated autism screening in a sample at higher likelihood (HL) for ASD, following both screen positives and all screen negatives to diagnostic outcome. Using a prospective infant sibling design, the current study followed 135 toddlers at HL for ASD and conducted diagnostic evaluations on the full sample at 18, 24, and 36 months. The psychometric properties of the M-CHAT-R using both concurrent and predictive diagnostic evaluations were compared in a group screened once (at 18 months only, n = 60) or twice (at both 18 and 24 months, n = 75). The study also examined consistency in reporting of ASD symptoms across the M-CHAT-R and a developmental concerns interview, comparing the HL group to a group with lower likelihood (LL) for ASD (n = 88). Sensitivity and specificity of the M-CHAT-R were high (75 - 95%), consistent with previous research. Positive predictive value (43 - 76%) was higher in this HL group than in previous community samples. Repeat screening improved sensitivity with little cost to specificity. At both 18 and 24 months, HL parents were more consistent in their reporting on the M-CHAT-R and a concerns interview than LL parents. The M-CHAT-R has strong psychometric properties when used with groups at HL for ASD, suggesting that scores over the screening cutoff of 3 should lead to prompt diagnostic evaluation referrals in children with older siblings on the spectrum.

EEG functional connectivity in infants at elevated familial likelihood for autism spectrum disorder

BackgroundMany studies have reported that autism spectrum disorder (ASD) is associated with atypical structural and functional connectivity. However, we know relatively little about the development of these differences in infancy.MethodsWe used a high-density electroencephalogram (EEG) dataset pooled from two independent infant sibling cohorts, to characterize such neurodevelopmental deviations during the first years of life. EEG was recorded at 6 and 12 months of age in infants at typical (N = 92) or elevated likelihood for ASD (N = 90), determined by the presence of an older sibling with ASD. We computed the functional connectivity between cortical sources of EEG during video watching using the corrected imaginary part of phase-locking values.ResultsOur main analysis found no significant association between functional connectivity and ASD, showing only significant effects for age, sex, age-sex interaction, and site. Given these null results, we performed an exploratory analysis and observed, at 12 months, a negative correlation between functional connectivity and ADOS calibrated severity scores for restrictive and repetitive behaviors (RRB).LimitationsThe small sample of ASD participants inherent to sibling studies limits diagnostic group comparisons. Also, results from our secondary exploratory analysis should be considered only as potential relationships to further explore, given their increased vulnerability to false positives.ConclusionsThese results are inconclusive concerning an association between EEG functional connectivity and ASD in infancy. Exploratory analyses provided preliminary support for a relationship between RRB and functional connectivity specifically, but these preliminary observations need corroboration on larger samples.

Predicting self-injurious behavior at age three among infant siblings of children with autism.

Existing research suggests that self-injurious behavior (SIB) is a relatively common interfering behavior that can occur across the lifespan of individuals with autism spectrum disorder (ASD). We previously reported that SIB or proto-injurious SIB at 12 months was related to increased risk of SIB at 24 months among a preschool sample of children with a high familial likelihood for ASD (Dimian et al., 2017). In the present study, we extend these findings, examine SIB occurrence, and associated potential risk factors at 36 months. The present sample included 149 infants with an older sibling with ASD (65.8% male) who completed assessments at ages 12, 24, and 36 months. Descriptive analyses and binary logistic regression models were utilized. SIB was more prevalent among those children who received a diagnosis of ASD. Logistic regression indicated that presence of SIB, stereotypy, hyper- and hypo- sensory responsivity, and lower intellectual functioning at age 12 months significantly predicted the occurrence of SIB at 36 months. These findings have implications for understanding developmental processes culminating in persistent SIB and may inform prevention programming.

Using the Infant Sibling-Design to Explore Associations Between Autism and ADHD Traits in Probands and Temperament in the Younger Siblings

The purpose of the current study was to use the infant sibling design to explore whether proband traits of autism and ADHD could provide information about their infant sibling’s temperament. This could help us to gain information about the extent to which infant temperament traits are differentially associated with autism and ADHD traits. We used parent-ratings of autistic traits and ADHD traits (CRS-3) in older siblings diagnosed with autism (age range 4 to 19 years), and their infant siblings’ temperament traits (IBQ) at 9 months of age in 216 sibling pairs from two sites (BASIS, UK, and EASE, Sweden) to examine associations across siblings. We found specific, but modest, associations across siblings after controlling for sex, age, developmental level and site. Proband autistic traits were specifically related to low levels of approach in the infant siblings, with infant developmental level explaining part of the variance in infant approach. Proband ADHD traits were specifically related to high levels of infant activity even after controlling for covariates. Our findings suggest that proband traits of autism and ADHD carry information for infant sibling’s temperament, indicating that inherited liability may influence early emerging behaviours in infant siblings. The impact of sex, age, developmental level and site are discussed.

Parent-child interaction and developmental outcomes in children with typical and elevated likelihood of autism

BackgroundEarly parent-child interactions have a critical impact on the developmental outcomes of the child. It has been reported that infants with a family history of autism and their parents may engage in different patterns of behaviours during interaction compared to those without a family history of autism. This study investigated the association of parent-child interactions with child developmental outcomes of those with typical and elevated likelihood of autism. MethodThis longitudinal study investigated the relationship between global attributes of parent-child interaction and the developmental outcomes of infant siblings with elevated likelihood (EL: n = 29) or typical likelihood (TL: n = 39) of developing autism. Parent-child interactions were recorded during a session of free-play when the infants were six months of age. Developmental assessments were carried out when the children were 12 and 24 months of age. ResultsThe intensity of mutuality was significantly higher in the TL group than in the EL group, and developmental outcomes were poorer in the EL group when compared to the TL group. Positive associations between parent-child interaction scores at six months and developmental outcomes at 12 months were observed only in the TL group. However, in the EL group, higher levels of infant positive affect and attentiveness paid to the caregiver is associated with lower autism symptoms. Due to the sample size and design of the study, the findings must be viewed as indicative. ConclusionThis preliminary investigation demonstrated differences in the association between parent-child interaction quality and developmental outcomes for children with typical and elevated likelihood for autism. Future studies should combine micro-analytic and macro-analytic approaches to parent-child interaction to further examine the nature of this relationship.

Factors related to retention in a longitudinal study of infants at familial risk for autism.

Reporting retention data is critical to determining the soundness of a study's conclusions (internal validity) and broader generalizability (external validity). Although selective attrition can lead to overestimates of effects, biased conclusions, or overly expansive generalizations, retention rates are not reported in many longitudinal studies. We examined multiple child- and family-level factors potentially associated with retention in a longitudinal study of younger siblings of children with autism spectrum disorder (ASD; n=304) or typical development (n=163). The sample was followed from the first year of life to 36months of age, for up to 7 visits. Of the 467 infant siblings who were consented and participated in at least one research visit, 397 (85.0%) were retained to study completion at 36months. Retention rates did not differ by familial risk group (ASD-risk vs. Low-risk), sex, race, ethnicity, age at enrollment, number of children in the family, maternal employment, marital status, or parent concerns about the child at enrollment. A stepwise regression model identified 4 variables that, together, provided the most parsimonious predictive model of study retention: maternal education, maternal age at child's birth, travel distance to the study site, and diagnostic outcome classification at the final study visit. The retained and not-retained groups did not differ on most demographic and clinical variables, suggesting few threats to internal and external validity. The significantly higher rate of retention of children diagnosed with ASD (95%) than typically developing children (83%) may, however, present biases when studying recurrence risk. We conclude by describing engagement and tracking methods that can be used to maximize retention in longitudinal studies of children at risk of ASD.

Associations Between Caregiver Stress and Language Outcomes in Infants With Autistic and Non-Autistic Siblings: An Exploratory Study.

Caregivers of autistic children present with high stress levels, which have been associated with poorer child outcomes in several domains, including language development. However, prior to this study, it was unknown whether elevated caregiver stress was associated with language development in infant siblings of autistic children (Sibs-autism), who are at increased likelihood of receiving a future diagnosis of autism and/or language impairment compared to infant siblings of non-autistic children. This study explored the degree to which, as well as the mechanisms by which, caregiver stress was linked with later language outcomes of Sibs-autism and infant siblings of non-autistic children (Sibs-NA). Participants were 50 infants (28 Sibs-autism; 22 Sibs-NA) aged 12-18 months at the first time point in this study (Time 1). Infants were seen again 9 months later, at 21-27 months of age (Time 2). Caregiver stress was measured via a validated self-report measure at Time 1. Caregiver language input, the putative mechanism by which caregiver stress may influence later language outcomes, was collected via two daylong recordings from digital recording (Language ENvironment Analysis) devices worn by the child at this same time point. Child language outcomes were measured via standardized and caregiver report measures at Time 2. Several models testing hypothesized indirect effects of caregiver stress on later child language outcomes through caregiver language input were statistically significant. Specifically, significant indirect effects suggest that (a) caregivers with increased stress tend to speak less to their infants, and (b) this reduced language input tends to covary with reduced child language outcomes later in life for Sibs-autism and Sibs-NA. This study provides new insights into links between caregiver stress, caregiver language input, and language outcomes in Sibs-autism and Sibs-NA. Further work is necessary to understand how to best support caregivers and optimize the language learning environments for infants. https://doi.org/10.23641/asha.21714368.

Bidding on the go: Links between walking, social actions, and caregiver responses in infant siblings of children with autism spectrum disorder.

The development of walking is associated with a shift in how neurotypical infants initiate social interactions. Walking infants are more likely to locate objects in distant places, carry them, and then share those objects by approaching caregivers and using gestures to show or offer their discoveries (i.e., moving bids). The simultaneous organization of the behaviors necessary to generate moving bids requires the coordination of multiple skills-walking, fine motor skills, and gesturing. Infants with an elevated likelihood (EL) for autism spectrum disorder (ASD) exhibit differences and delays in each of these behaviors. This study investigated interconnections between infant walking, social actions, and caregiver responses in 18-month-old EL infants with diverse developmental outcomes (ASD, non-ASD language delay, no diagnosis). We observed 85 infant-caregiver dyads at home during everyday activities for 45 minutes and identified all times when infants walked, instances of walking paired with social action (i.e., approaching the caregiver, approaching while carrying an object, producing a moving bid), and whether caregivers responded to their infants' social actions. There were no group differences in infants' production of social actions. Caregiver responses, however, were more clearly modulated by outcome group. While all caregivers were similarly and highly likely to respond to moving bids, caregivers of EL-ASD infants were substantially more likely to respond when their infants simply approached them (with or without an object in hand). Taken together, this research underscores the complexity of EL infant-caregiver interactions and highlights the role that each partner plays in shaping how they unfold.