Cognitive and behavioral differences in toddlers with autism spectrum disorder from multiplex and simplex families

Early identification of autism spectrum disorder based on machine learning with eye-tracking data

BACKGROUND

Early identification of autism spectrum disorder (ASD) improves long-term outcomes, yet significant diagnostic delays persist.

METHODS

A retrospective cohort of 449 children (ASD: 246, typically developing [TD]: 203) was used for model development. Eye-movement data were collected from the participants watching videos that featured eye-tracking paradigms for assessing social and non-social cognition. Five machine learning algorithms, namely random forest, support vector machine, logistic regression, artificial neural network, and extreme gradient boosting, were trained to classify children with ASD and TD. The best-performing algorithm was selected to build the final model which was further evaluated in a prospective cohort of 80 children. The Shapley values interpreted important eye-tracking features.

RESULTS

Random forest outperformed other algorithms during model development and achieved an area under the curve of 0.849 (< 3 years: 0.832, ≥ 3 years: 0.868) on the external validation set. Of the ten most important eye-tracking features, three measured social cognition, and the rest were related to non-social cognition. A deterioration in model performance was observed using only the social or non-social cognition-related eye-tracking features.

LIMITATIONS

The sample size of this study, although larger than that of existing studies of ASD based on eye-tracking data, was still relatively small compared to the number of features.

CONCLUSIONS

Machine learning models based on eye-tracking data have the potential to be cost- and time-efficient digital tools for the early identification of ASD. Eye-tracking phenotypes related to social and non-social cognition play an important role in distinguishing children with ASD from TD children.

Parent-Child Interactions May Help to Explain Relations Between Parent Characteristics and Clinically Observed Child Autistic Behaviours

The importance of supporting parent-child interactions has been noted in the context of prodromal autism, but little consideration has been given to the possible contributing role of parental characteristics, such as psychological distress. This cross-sectional study tested models in which parent-child interaction variables mediated relations between parent characteristics and child autistic behaviour in a sample of families whose infant demonstrated early signs of autism (N = 103). The findings suggest that associations between parent characteristics (psychological distress; aloofness) and child autistic behaviours may be mediated by the child's inattentiveness or negative affect during interactions. These findings have important implications in developing and implementing interventions in infancy which target the synchrony of parent-child interaction with the goal to support children's social communication development.

Examination of Clinical and Assessment Type Differences Between Toddlers with ASD from Multiplex and Simplex Families

Few studies have examined differences in autism spectrum disorder (ASD) phenotype between children from multiplex and simplex families at the time of diagnosis. The present study used an age- and gender-matched, community-based sample (n = 105) from the southwestern United States to examine differences in ASD symptom severity, cognitive development, and adaptive functioning. No significant differences between children from multiplex and simplex families were observed. Exploratory analysis revealed that parents underreported receptive and expressive language and fine motor skills compared to professional observation, especially among children from multiplex families. These findings suggest that diagnosticians may need to consider family structure when choosing and interpreting assessments of receptive language, expressive language, and fine motor skills.

From personification abuse to normal expression: emotional treatment for language disorders in schools

Introduction

The escalating prevalence of personification abuse in language disorders among students poses a substantial challenge for autistic students in the domain of language disorders. While prior research has mainly focused on the cognitive hurdles faced by autistic students, ongoing debates persist about the onset, severity, and roots of these challenges in their classroom behavior, with limited exploration of how preconceived notions impact personification abuse. This study aims to delve into emotional treatments for language disorders, specifically targeting personification abuse, to facilitate the shift from distorted perceptions to normative expression. It seeks to pinpoint the primary emotional interventions linked to instances of personification abuse and scrutinize the emotional factors influencing therapeutic approaches for language disorders.

Methods

The research encompassed a cohort of 110 autistic students, aged 2 to 5 years, diagnosed with language disorders, all clinically determined to have autism by developmental pediatricians at a prestigious medical facility. Among these children, 95 were attending specialized schools, while 15 were situated in community settings.

Results

The outcomes disclosed that children across all developmental phases displayed instances of personification abuse in language disorders, showcasing noteworthy enhancements in personification abuse following emotional treatment. Significantly, the discernible disparity in personification abuse performance and emotional treatment can be linked to the simultaneous cognitive advancement of autistic students across four grade levels, with variations noted based on normative expressions.

Discussion

These findings underscore the insufficiency of solely relying on intrinsic trends to comprehend personification abuse within an emotional treatment context. The study accentuates the potential pitfalls associated with emotional treatment for language disorders and stresses the imperative need for additional research and psychiatric intervention strategies.

Differential cognitive and behavioral development from 6 to 24 months in autism and fragile X syndrome

BACKGROUND

Specifying early developmental differences among neurodevelopmental disorders with distinct etiologies is critical to improving early identification and tailored intervention during the first years of life. Recent studies have uncovered important differences between infants with fragile X syndrome (FXS) and infants with familial history of autism spectrum disorder who go on to develop autism themselves (FH-ASD), including differences in brain development and behavior. Thus far, there have been no studies longitudinally investigating differential developmental skill profiles in FXS and FH-ASD infants.

METHODS

The current study contrasted longitudinal trajectories of verbal (expressive and receptive language) and nonverbal (gross and fine motor, visual reception) skills in FXS and FH-ASD infants, compared to FH infants who did not develop ASD (FH-nonASD) and typically developing controls.

RESULTS

Infants with FXS showed delays on a nonverbal composite compared to FH-ASD (as well as FH-nonASD and control) infants as early as 6 months of age. By 12 months an ordinal pattern of scores was established between groups on all domains tested, such that controls > FH-nonASD > FH-ASD > FXS. This pattern persisted through 24 months. Cognitive level differentially influenced developmental trajectories for FXS and FH-ASD.

CONCLUSIONS

Our results demonstrate detectable group differences by 6 months between FXS and FH-ASD as well as differential trajectories on each domain throughout infancy. This work further highlights an earlier onset of global cognitive delays in FXS and, conversely, a protracted period of more slowly emerging delays in FH-ASD. Divergent neural and cognitive development in infancy between FXS and FH-ASD contributes to our understanding of important distinctions in the development and behavioral phenotype of these two groups.

An affective assessment: incarnate biases in picture captions for autistic children

Previous studies have explored cognitive disabilities experienced by autistic children between the ages of 2 and 5 who attend special schools. However, there is still debate regarding the onset, scope, and causes of these problems, particularly when considering incarnate biases that may arise from affective notions. Early affective issues could potentially be a key factor contributing to observing such biases in picture captions. In this study, we employed an affective approach-simultaneous observation and questionnaire-to investigate how incarnate biases impact picture caption activities. Specifically, we looked at the performances of autistic children across four grades: PreK, K1, K2, and K3. We found that autistic children across all grades demonstrated instances of incarnation-biased interpretations in picture captions, although K3 performed better than the other grades. Furthermore, their incarnate biases tended to be negative rather than positive in affection, depending on the level of activity involved. Ultimately, the sources of these incarnate biases may stem from three spheres: school, society, and family. Thus, it is essential to consider these factors when designing educational programs for children with autism. It highlights the potential dangers associated with negative biases in picture captions. Unlike previous studies that focused on identifying discrepancies in picture caption, our research suggests that over time, as we take into account the onset of incarnate biases from the three affective spheres discussed in this study, picture caption may improve among autistic children as their incarnate biases decrease.

Heterogeneity of autism symptoms in community-referred infants and toddlers at elevated or low familial likelihood of autism

Evidence suggests autistic individuals at elevated familial likelihood of autism spectrum disorder (by virtue of having an autistic sibling) have stronger cognitive abilities on average than autistic individuals with no family history of the condition, who have a low familial likelihood of autism. Investigating phenotypic differences between community-referred infants and toddlers with autism symptoms at elevated or low familial likelihood of autism may provide important insight into heterogeneity in the emerging autism phenotype. This study compared behavioral, cognitive, and language abilities of community-referred infants and toddlers with confirmed autism symptoms at elevated (EL) or low familial likelihood of autism (LL). Participants were 121 children aged 12 to 36 months who participated in two larger randomized trials of parent-mediated interventions for children with autism symptoms. Behavioral phenotypes were compared across three groups: children with at least one autistic sibling (EL-Sibs, n = 30), those with at least one older, non-autistic sibling and no family history of autism (LL-Sibs, n = 40), and first-born children with no family history of autism (LL-FB, n = 51). EL-Sibs had less severe autism symptoms and stronger cognitive abilities than children in LL groups. While the rate of receptive language delay was similar across groups, the rate of expressive language delay was markedly lower among EL-Sibs. After controlling for age and nonverbal cognitive ability, EL-Sibs were significantly less likely to present with expressive language delay than LL-Sibs. Familial likelihood of autism may play an important role in shaping the emerging autism phenotype in infancy and toddlerhood.

The first six months of life: A systematic review of early markers associated with later autism

There is now good evidence that behavioural signs of autism spectrum conditions (autism) emerge over the first two years of life. Identifying clear developmental differences early in life may facilitate earlier identification and intervention that can promote longer-term quality of life. Here we present a systematic review of studies investigating behavioural markers of later autism diagnosis or symptomology taken at 0-6 months. The following databases were searched for articles published between 01/01/2000 and 15/03/2022: Embase, Medline, Scopus, PubMed, PsycINFO, CINAHL, Web of Science and Proquest. Twenty-five studies met inclusion criteria: assessment of behaviour at 0-6 months and later assessment of autism symptomology or diagnosis. Studies examined behaviours of attention, early social and communication behaviours, and motor behaviours, as well as composite measures. Findings indicated some evidence of measures of general attention, attention to social stimuli, and motor behaviours associated with later autism diagnosis or symptomology. Findings were inconsistent regarding social and communication behaviours, with a lack of repeated or validated measures limiting drawing firm conclusions. We discuss implications of the findings and suggest recommendations for future research.

Infants later diagnosed with autism have lower canonical babbling ratios in the first year of life

BACKGROUND

Canonical babbling-producing syllables with a mature consonant, full vowel, and smooth transition-is an important developmental milestone that typically occurs in the first year of life. Some studies indicate delayed or reduced canonical babbling in infants at high familial likelihood for autism spectrum disorder (ASD) or who later receive an ASD diagnosis, but evidence is mixed. More refined characterization of babbling in the first year of life in infants with high likelihood for ASD is needed.

METHODS

Vocalizations produced at 6 and 12 months by infants (n = 267) taking part in a longitudinal study were coded for canonical and non-canonical syllables. Infants were categorized as low familial likelihood (LL), high familial likelihood diagnosed with ASD at 24 months (HL-ASD) or not diagnosed (HL-Neg). Language delay was assessed based on 24-month expressive and receptive language scores. Canonical babble ratio (CBR) was calculated by dividing the number of canonical syllables by the number of total syllables. Generalized linear (mixed) models were used to assess the relationship between group membership and CBR, controlling for site, sex, and maternal education. Logistic regression was used to assess whether canonical babbling ratios at 6 and 12 months predict 24-month diagnostic outcome.

RESULTS

No diagnostic group differences in CBR were detected at 6 months, but HL-ASD infants produced significantly lower CBR than both the HL-Neg and LL groups at 12 months. HL-Neg infants with language delay also showed reduced CBR at 12 months. Neither 6- nor 12-month CBR was significant predictors of 24-month diagnostic outcome (ASD versus no ASD) in logistic regression.

LIMITATIONS

Small numbers of vocalizations produced by infants at 6 months may limit the reliability of CBR estimates. It is not known if results generalize to infants who are not at high familial likelihood, or infants from more diverse racial and socioeconomic backgrounds.

CONCLUSIONS

Lower canonical babbling ratios are apparent by the end of the first year of life in ASD regardless of later language delay, but are also observed for infants with later language delay without ASD. Canonical babbling may lack specificity as an early marker when used on its own.

The course and prognostic capability of motor difficulties in infants showing early signs of autism

Delays within the motor domain are often overlooked as an early surveillance marker for autism. The present study evaluated motor difficulties and its potential as an early predictive marker for later autism likelihood in a cohort of infants (N = 96) showing early behavioral signs of autism aged 9-14 months. The motor domain was evaluated using the motor subscales of the Mullen Scales of Early Learning at baseline, and at a 6-month follow-up. The Autism Diagnostic Observation Schedule - Toddler Module (ADOS-T) was completed at follow-up as a measure of autism likelihood. Motor difficulties were common at baseline, with 63/96 (65.6%) infants scoring very low or below average in the gross motor domain and 29/96 (30.2%) in the fine motor domain. At follow-up, gross motor difficulties had resolved for many, with 23/63 (36.5%) infants maintaining these difficulties. Fine motor difficulties resolved in fewer infants, with 20/29 (69.0%) continuing to present with fine motor delays at follow-up. Adjusted linear regression models suggested that fine motor scores at baseline (β = -0.12, SE = 0.04) and follow-up (β = -0.17, SE = 0.05) were associated with higher ADOS-T scores; with difficulties across both timepoints (β = 5.60, SE = 1.35) the strongest (largest in magnitude) association with ADOS-T scores of the predictors examined. Motor difficulties are prominent in children displaying emerging signs of autism, with persistent fine motor difficulties predictive of the developing autism phenotype. The findings indicate the potential clinical value of including evaluation of motor skills within early autism surveillance measures. LAY SUMMARY: This prospective study evaluated motor development over a 6-month period in infants showing early behavioral signs of autism. Atypical motor development was a common feature of infants showing early signs of autism and persistent fine motor difficulties were predictive of the emerging autism phenotype.

Exons as units of phenotypic impact for truncating mutations in autism

Autism spectrum disorders (ASD) are a group of related neurodevelopmental diseases displaying significant genetic and phenotypic heterogeneity. Despite recent progress in understanding ASD genetics, the nature of phenotypic heterogeneity across probands remains unclear. Notably, likely gene-disrupting (LGD) de novo mutations affecting the same gene often result in substantially different ASD phenotypes. Nevertheless, we find that truncating mutations affecting the same exon frequently lead to strikingly similar intellectual phenotypes in unrelated ASD probands. Analogous patterns are observed for two independent proband cohorts and several other important ASD-associated phenotypes. We find that exons biased toward prenatal and postnatal expression preferentially contribute to ASD cases with lower and higher IQ phenotypes, respectively. These results suggest that exons, rather than genes, often represent a unit of effective phenotypic impact for truncating mutations in autism. The observed phenotypic patterns are likely mediated by nonsense-mediated decay (NMD) of splicing isoforms, with autism phenotypes usually triggered by relatively mild (15-30%) decreases in overall gene dosage. We find that each ASD gene with recurrent mutations can be characterized by a parameter, phenotype dosage sensitivity (PDS), which quantifies the relationship between changes in a gene's dosage and changes in a given disease phenotype. We further demonstrate analogous relationships between exon LGDs and gene expression changes in multiple human tissues. Therefore, similar phenotypic patterns may be also observed in other human genetic disorders.

12-Month peak alpha frequency is a correlate but not a longitudinal predictor of non-verbal cognitive abilities in infants at low and high risk for autism spectrum disorder

Although studies of PAF in individuals with autism spectrum disorder (ASD) report group differences and associations with non-verbal cognitive ability, it is not known how PAF relates to familial risk for ASD, and whether similar associations with cognition in are present in infancy. Using a large multi-site prospective longitudinal dataset of infants with low and high familial risk for ASD, metrics of PAF at 12 months were extracted and growth curves estimated for cognitive development between 12-36 months. Analyses tested whether PAF 1) differs between low and high risk infants, 2) is associated with concurrent non-verbal/verbal cognitive ability and 3) predicts developmental change in non-verbal/verbal ability. Moderation of associations between PAF and cognitive ability by familial risk status was also tested. No differences in 12-month PAF were found between low and high risk infants. PAF was associated with concurrent non-verbal cognitive ability, but did not predict change in non-verbal cognitive over development. No associations were found between PAF and verbal ability, along with no evidence of moderation. PAF is not related to familial risk for ASD, and is a neural marker of concurrent non-verbal cognitive ability, but not verbal ability, in young infants at low and high risk for ASD.

Attentional bias to fearful faces in infants at high risk for autism spectrum disorder

Individuals with autism spectrum disorder (ASD) and their first-degree relatives show differences from neurotypical individuals in emotional face processing. Prospective studies of infant siblings of children with ASD, a group at high risk for autism (HRA), allow researchers to examine the early emergence of these differences. This study used eye tracking to examine disengagement of attention from emotional faces (fearful, happy, neutral) at 6, 9, and 12 months in low-risk control infants (LRC) and HRA infants who received a subsequent clinical judgment of ASD (HRA+) or non-ASD (HRA-). Infants saw centrally presented faces followed by a peripheral distractor (with face remaining present). For each emotion, latency to shift to the distractor and percentage of trials with no shift were calculated. Results showed increased saccadic latency and a greater percentage of no-shift trials for fearful faces. No between-group differences were present for emotion; however, there was an interaction between age and group for disengagement latency, with HRA+ infants slower to shift at 12 months compared with the other 2 groups. Exploratory correlational analyses looking at shift biases to fearful faces alongside measures of social behavior at 12 and 18 months (from the Communication and Symbolic Behavior Scales) revealed that for HRA+ infants, 9- and 12-month fear biases were significantly related to 12- and 18-month social abilities, respectively. This work suggests that both low- and high-risk infants show biases to threat-relevant faces, and that for HRA+, differences in attention shifting emerge with age, and a stronger fear bias could potentially relate to less social difficulty. (PsycInfo Database Record (c) 2020 APA, all rights reserved).

DAS-II Cognitive Profiles Are Not Diagnostically Meaningful For Autism: A ROC Analysis

Intelligence assessment is an integral part of a comprehensive autism evaluation. Many past studies have described a cognitive profile of autistic individuals characterized by higher nonverbal than verbal IQ scores. The diagnostic utility of this profile, however, remains unknown. We leveraged receiver operating characteristic methods to determine the sensitivity, specificity, and area under the curve (AUC) of three different IQ profiles in a large sample of children who have an autism spectrum disorder diagnosis (N = 1,228, Simons Simplex Collection) who completed the Differential Ability Scales-Second Edition (DAS-II), School Age compared to the normative sample provided by the DAS-II publisher (N = 2,200). The frequently discussed nonverbal > verbal IQ profile performed near chance at distinguishing ASD from normative individuals (AUC: 0.54, 95% CI [0.52-0.56]), and performed significantly worse for females than males (AUC: females: 0.46 [0.41-0.52]; males: 0.55 [0.53-0.58]). All cognitive profiles showed AUC < 0.56. We conclude that while significant differences between verbal and nonverbal IQ scores exist at the group level, these differences are small in an absolute sense and not meaningful at an individual level. We do not recommend using cognitive profiles to aid in autism diagnostic decision-making. LAY SUMMARY: Some researchers and clinicians have reported an "autistic cognitive profile" of higher nonverbal intelligence than verbal intelligence. In an analysis of over 1,000 autistic children, we found that the group's average nonverbal intelligence is usually higher than their verbal intelligence. However, this pattern should not be used by clinicians to make an individual diagnosis of autism because our results show it is not helpful nor accurate.

The development of the social brain in baby siblings of children with autism

PURPOSE OF REVIEW

Impairments in social interaction/communication become apparent after 12 months of age in children who develop Autism spectrum disorder (ASD). Studies of baby siblings of children with ASD provide the means to detect changes in the brain that are present before behavioral symptoms appear. In this review, advances from brain imaging studies of infant siblings over the past 18 months are highlighted.

RECENT FINDINGS

During the first 2 months of life, functional differences in social brain regions and microstructural differences in dorsal language tracks are found in some high-risk baby siblings. At 4-6 months of age, differences in subcortical and cerebellum volumes and atypical cortical responses to social stimuli are evident. At 6 months, extra-axial cerebrospinal fluid is increased, and at 8 months there is evidence of cortical hyper-reactivity. Patterns of functional connectivity are distinct in infant siblings and suggest dysfunctional activation and integration of information across the cortex and neural networks underlying social behaviors.

SUMMARY

Further replication in very large independent samples is needed to verify the majority of the findings discussed and understand how they are related within individual infants. Much more research is needed before translation to clinical practice.

Pre-emptive Intervention for Autism Spectrum Disorder: Theoretical Foundations and Clinical Translation

Autism spectrum disorders (ASD) are an emergent public health problem, placing significant burden upon the individual, family and health system. ASD are polygenetic spectrum disorders of neural connectome development, in which one or more feedback loops amplify small genetic, structural, or functional variations in the very early development of motor and sensory-motor pathways. These perturbations trigger a 'butterfly effect' of unpredictable cascades of structural and functional imbalances in the global neuronal workspace, resulting in atypical behaviors, social communication, and cognition long-term. The first 100 days post-term are critically neuroplastic and comprise an injury-sensitive developmental window, characterized by a neural biomarker, the persistence of the cortical subplate, and a behavioral biomarker, the crying diathesis. By the time potential diagnostic signs are identified, from 6 months of age, ASD neuropathy is already entrenched. The International Society for Autism Research Special Interest Group has called for pre-emptive intervention, based upon rigorous theoretical frames, and real world translation and evaluation. This paper responds to that call. It synthesizes heterogenous evidence concerning ASD etiologies from both psychosocial and biological research literatures with complexity science and evolutionary biology, to propose a theoretical framework for pre-emptive intervention. This paper hypothesizes that environmental factors resulting from a mismatch between environment of evolutionary adaptedness and culture initiate or perpetuate early motor and sensory-motor lesions, triggering a butterfly effect of multi-directional cascades of atypical developmental in the complex adaptive system of the parent and ASD-susceptible infant. Chronic sympathetic nervous system/hypothalamic-pituitary-adrenal axis hyperarousal and disrupted parent-infant biobehavioral synchrony are the key biologic and behavioral mechanisms perpetuating these atypical developmental cascades. A clinical translation of this evidence is proposed, for application antenatally and in the first 6 months of life, as pre-emptive intervention for ASD.

Differences in Cognition and Behaviour in Multiplex and Simplex Autism: Does Prior Experience Raising a Child with Autism Matter?

Previous research has found multiplex (MPX) children have an advantage in cognition compared to simplex (SPX) children. However, MPX parent's previous experience with older diagnosed siblings has not been considered. We used a large database sample to investigate the MPX advantage and contribution of birth order. Children from the Autism Genetic Resource Exchange (AGRE) were stratified into first- (MPX¹, n  = 152) and second-affected MPX (MPX², n  = 143), SPX (n  = 111), and only-child SPX (SPX^OC, n  = 23) groups. Both MPX groups had higher cognitive scores compared to SPX groups, with no differences between MPX¹ and MPX² groups. No differences were found for autism symptoms or adaptive behaviour. These results suggest parent experience due to birth order is an unlikely contributor to the MPX cognitive advantage.

Pre-emptive intervention versus treatment as usual for infants showing early behavioural risk signs of autism spectrum disorder: a single-blind, randomised controlled trial

BACKGROUND

Great interest exists in the potential efficacy of prediagnostic interventions within the autism spectrum disorder prodrome, but available evidence relates to children at high familial risk. We aimed to test the efficacy of a pre-emptive intervention designed for infants showing early behavioural signs of autism spectrum disorder.

METHODS

In this single-blind, randomised controlled trial done at two specialist centres in Australia, infants aged 9-14 months were enrolled if they were showing at least three early behavioural signs of autism spectrum disorder on the Social Attention and Communication Surveillance-Revised (SACS-R) 12-month checklist. Infants were randomly assigned (1:1) to receive a parent-mediated video-aided intervention (iBASIS-VIPP) or treatment as usual. Group allocation was done by minimisation, stratified by site, sex, age, and the number of SACS-R risk behaviours. Assessments were done at baseline (before treatment allocation) and at the 6 month endpoint. The primary outcome was Autism Observation Scale for Infants (AOSI), which measures early behavioural signs associated with autism spectrum disorder. Secondary outcomes were a range of infant and caregiver outcomes measured by Manchester Assessment of Caregiver-Infant interaction (MACI), Mullen Scales of Early Learning (MSEL), Vineland Adaptive Behaviour Scales, 2nd edition (VABS-2), MacArthur-Bates Communicative Development Inventory (MCDI), and Parenting Sense of Competence (PSOC) scale. This trial is registered with Australian New Zealand Clinical Trials Registry, number ANZCTR12616000819426.

FINDINGS

Between June 9, 2016, and March 30, 2018, 103 infants were randomly assigned, 50 to the iBASIS-VIPP group and 53 to the treatment-as-usual group. After the intervention, we observed no significant differences between groups on early autism spectrum disorder behavioural signs measured by the AOSI (difference estimate -0·74, 95% CI -2·47 to 0·98). We also observed no significant differences on secondary outcomes measuring caregiver non-directiveness (0·16, -0·33 to 0·65), caregiver sensitive responding (0·24, -0·15 to 0·63), and infant attentiveness (-0·19, -0·63 to 0·25) during parent-child interactions (MACI), as well as on researcher-administered measures of receptive (1·30, -0·48 to 3·08) and expressive language (0·54, -0·73 to 1·80), visual reception (0·31, -0·77 to 1·40), and fine motor skills (0·55, -0·32 to 1·41) using the MSEL. Compared with the treatment-as-usual group, the iBASIS-VIPP group had lower infant positive affect (-0·69, -1·27 to -0·10) on the MACI, but higher caregiver-reported receptive (37·17, 95% CI 10·59 to 63·75) and expressive vocabulary count (incidence rate ratio 2·31, 95% CI 1·22 to 4·33) on MCDI, and functional language use (difference estimate 6·43, 95% CI 1·06 to 11·81) on VABS. There were no significant group differences on caregiver-reported measures of MCDI infant gesture use (3·22, -0·60 to 7·04) and VABS social behaviour (3·28, -1·43 to 7·99). We observed no significant differences between groups on self-reported levels of parenting satisfaction (difference estimate 0·21, 95% CI -0·09 to 0·52), interest (-0·23, -0·62 to 0·16) and efficacy (-0·08, -0·38 to 0·22) on PSOC.

INTERPRETATION

A pre-emptive intervention for the autism spectrum disorder prodrome had no immediate treatment effect on early autism spectrum disorder symptoms, the quality of parent-child interactions, or researcher-administered measures of developmental skills. However, we found a positive effect on parent-rated infant communication skills. Ongoing follow-up of this infant cohort will assess longer-term developmental effects.

FUNDING

Western Australia Children's Research Fund, Autism Cooperative Research Centre, La Trobe University, and Angela Wright Bennett Foundation.