Infant-directed song potentiates infants' selective attention to adults' mouths over the first year of life.

The mechanisms by which infant-directed (ID) speech and song support language development in infancy are poorly understood, with most prior investigations focused on the auditory components of these signals. However, the visual components of ID communication are also of fundamental importance for language learning: over the first year of life, infants' visual attention to caregivers' faces during ID speech switches from a focus on the eyes to a focus on the mouth, which provides synchronous visual cues that support speech and language development. Caregivers' facial displays during ID song are highly effective for sustaining infants' attention. Here we investigate if ID song specifically enhances infants' attention to caregivers' mouths. 299 typically developing infants watched clips of female actors engaging them with ID song and speech longitudinally at six time points from 3 to 12 months of age while eye-tracking data was collected. Infants' mouth-looking significantly increased over the first year of life with a significantly greater increase during ID song versus speech. This difference was early-emerging (evident in the first 6 months of age) and sustained over the first year. Follow-up analyses indicated specific properties inherent to ID song (e.g., slower tempo, reduced rhythmic variability) in part contribute to infants' increased mouth-looking, with effects increasing with age. The exaggerated and expressive facial features that naturally accompany ID song may make it a particularly effective context for modulating infants' visual attention and supporting speech and language development in both typically developing infants and those with or at risk for communication challenges. A video abstract of this article can be viewed at https://youtu.be/SZ8xQW8h93A. RESEARCH HIGHLIGHTS: Infants' visual attention to adults' mouths during infant-directed speech has been found to support speech and language development. Infant-directed (ID) song promotes mouth-looking by infants to a greater extent than does ID speech across the first year of life. Features characteristic of ID song such as slower tempo, increased rhythmicity, increased audiovisual synchrony, and increased positive affect, all increase infants' attention to the mouth. The effects of song on infants' attention to the mouth are more prominent during the second half of the first year of life.

Infant viewing of social scenes is under genetic control and is atypical in autism.

Long before infants reach, crawl or walk, they explore the world by looking: they look to learn and to engage, giving preferential attention to social stimuli, including faces, face-like stimuli and biological motion. This capacity-social visual engagement-shapes typical infant development from birth and is pathognomonically impaired in children affected by autism. Here we show that variation in viewing of social scenes, including levels of preferential attention and the timing, direction and targeting of individual eye movements, is strongly influenced by genetic factors, with effects directly traceable to the active seeking of social information. In a series of eye-tracking experiments conducted with 338 toddlers, including 166 epidemiologically ascertained twins (enrolled by representative sampling from the general population), 88 non-twins with autism and 84 singleton controls, we find high monozygotic twin-twin concordance (0.91) and relatively low dizygotic concordance (0.35). Moreover, the characteristics that are the most highly heritable, preferential attention to eye and mouth regions of the face, are also those that are differentially decreased in children with autism (χ2 = 64.03, P < 0.0001). These results implicate social visual engagement as a neurodevelopmental endophenotype not only for autism, but also for population-wide variation in social-information seeking. In addition, these results reveal a means of human biological niche construction, with phenotypic differences emerging from the interaction of individual genotypes with early life experience.

Eye-Tracking-Based Measurement of Social Visual Engagement Compared With Expert Clinical Diagnosis of Autism.

Importance: In the US, children with signs of autism often experience more than 1 year of delay before diagnosis and often experience longer delays if they are from racially, ethnically, or economically disadvantaged backgrounds. Most diagnoses are also received without use of standardized diagnostic instruments. To aid in early autism diagnosis, eye-tracking measurement of social visual engagement has shown potential as a performance-based biomarker. Objective: To evaluate the performance of eye-tracking measurement of social visual engagement (index test) relative to expert clinical diagnosis in young children referred to specialty autism clinics. Design, Setting, and Participants: In this study of 16- to 30-month-old children enrolled at 6 US specialty centers from April 2018 through May 2019, staff blind to clinical diagnoses used automated devices to measure eye-tracking-based social visual engagement. Expert clinical diagnoses were made using best practice standardized protocols by specialists blind to index test results. This study was completed in a 1-day protocol for each participant. Main Outcomes and Measures: Primary outcome measures were test sensitivity and specificity relative to expert clinical diagnosis. Secondary outcome measures were test correlations with expert clinical assessments of social disability, verbal ability, and nonverbal cognitive ability. Results: Eye-tracking measurement of social visual engagement was successful in 475 (95.2%) of the 499 enrolled children (mean [SD] age, 24.1 [4.4] months; 38 [8.0%] were Asian; 37 [7.8%], Black; 352 [74.1%], White; 44 [9.3%], other; and 68 [14.3%], Hispanic). By expert clinical diagnosis, 221 children (46.5%) had autism and 254 (53.5%) did not. In all children, measurement of social visual engagement had sensitivity of 71.0% (95% CI, 64.7% to 76.6%) and specificity of 80.7% (95% CI, 75.4% to 85.1%). In the subgroup of 335 children whose autism diagnosis was certain, sensitivity was 78.0% (95% CI, 70.7% to 83.9%) and specificity was 85.4% (95% CI, 79.5% to 89.8%). Eye-tracking test results correlated with expert clinical assessments of individual levels of social disability (r = -0.75 [95% CI, -0.79 to -0.71]), verbal ability (r = 0.65 [95% CI, 0.59 to 0.70]), and nonverbal cognitive ability (r = 0.65 [95% CI, 0.59 to 0.70]). Conclusions and Relevance: In 16- to 30-month-old children referred to specialty clinics, eye-tracking-based measurement of social visual engagement was predictive of autism diagnoses by clinical experts. Further evaluation of this test's role in early diagnosis and assessment of autism in routine specialty clinic practice is warranted. Trial Registration: ClinicalTrials.gov Identifier: NCT03469986.

Early social communication development in infants with autism spectrum disorder.

Social-communication differences are a robust and defining feature of autism spectrum disorder (ASD) but identifying early points of divergence in infancy has been a challenge. The current study examines social communication in 9- to 12-month-old infants who develop ASD (N = 30; 23% female; 70% white) compared to typically developing (TD) infants (N = 94, 38% female; 88% white). Results demonstrate that infants later diagnosed with ASD were already exhibiting fewer social-communication skills using eye gaze, facial expression, gestures, and sounds at 9 months (effect size: 0.42-0.89). Moreover, three unique patterns of change across distinct social-communication skills were observed within the ASD group. This study documents that observable social-communication differences for infants with ASD are unfolding by 9 months, pointing to a critical window for targeted intervention.

Research Review: Outcomes of 24- to 36-month-old children with autism spectrum disorder vary by ascertainment strategy: a systematic review and meta-analysis.

BACKGROUND: Despite widespread recommendations for early surveillance of risk for autism spectrum disorder (ASD), no research to date has shown that early surveillance leads to better clinical outcomes. Preliminary research has suggested that children with ASD ascertained via prospective follow-up have better outcomes than those ascertained via community referral. Because prospective studies include early surveillance, by comparing outcomes of children with ASD across ascertainment strategies, we may gain insight into the effects of early surveillance relative to its absence. METHODS: A systematic review was conducted to identify studies reporting outcomes of 24- to 36-month-olds with ASD ascertained via prospective follow-up, community referral, or universal screening. A meta-analysis using a random effects model was used to calculate overall effect size estimates for developmental level and symptom severity across ascertainment cohorts. RESULTS: Eleven prospective, ten community referral, and eight universal screening studies were identified, reporting on 1,658 toddlers with ASD. We found no differences in outcomes between community referral and universal screening studies. Relative to both, prospective studies reported significantly higher developmental levels and lower symptom severities. CONCLUSIONS: Outcomes of young children with ASD ascertained via prospective follow-up are better than those of children with ASD recruited via community referral or universal screening. Although we discuss why sampling bias is not likely the driving force behind these findings, we cannot rule out the possibility that sampling bias contributes to the observed differences; future studies should probe the effects of sociodemographic variables on clinical outcomes as a function of ascertainment strategy. This limitation notwithstanding, our results raise the possibility that prospective follow-up may confer a 'surveillance effect' that contributes to improved developmental and diagnostic outcomes in children with ASD. Future research should test this hypothesis and determine the specific mechanism by which surveillance may improve outcomes.

Development of attention from birth to 5 months in infants at risk for autism spectrum disorder.

Social-communication skills emerge within the context of rich social interactions, facilitated by an infant's capacity to attend to people and objects in the environment. Disruption in this early neurobehavioral process may decrease the frequency and quality of social interactions and learning opportunities, potentially leading to downstream deleterious effects on social development. This study examined early attention in infant siblings of children with autism spectrum disorder (ASD) who are at risk for social and communication delays. Visual and auditory attention was mapped from age 1 week to 5 months in infants at familial risk for ASD (high risk; N = 41) and low-risk typically developing infants (low risk; N = 39). At 12 months, a subset of participants (N = 40) was administered assessments of social communication and nonverbal cognitive skills. Results revealed that high-risk infants performed lower on attention tasks at 2 and 3 months of age compared to low-risk infants. A significant association between overall attention at 3 months and developmental outcome at 12 months was observed for both groups. These results provide evidence for early vulnerabilities in visual attention for infants at risk for ASD during a period of important neurodevelopmental transition (between 2 and 3 months) when attention has significant implications for social communication and cognitive development.

Affording autism an early brain development re-definition.

The national priority to advance early detection and intervention for children with autism spectrum disorder (ASD) has not reduced the late age of ASD diagnosis in the US over several consecutive Centers for Disease Control and Prevention (CDC) surveillance cohorts, with traditionally under-served populations accessing diagnosis later still. In this review, we explore a potential perceptual barrier to this enterprise which views ASD in terms that are contradicted by current science, and which may have its origins in the current definition of the condition and in its historical associations. To address this perceptual barrier, we propose a re-definition of ASD in early brain development terms, with a view to revisit the world of opportunities afforded by current science to optimize children's outcomes despite the risks that they are born with. This view is presented here to counter outdated notions that potentially devastating disability is determined the moment a child is born, and that these burdens are inevitable, with opportunities for improvement being constrained to only alleviation of symptoms or limited improvements in adaptive skills. The impetus for this piece is the concern that such views of complex neurodevelopmental conditions, such as ASD, can become self-fulfilling science and policy, in ways that are diametrically opposed to what we currently know, and are learning every day, of how genetic risk becomes, or not, instantiated as lifetime disabilities.

Attention to eyes is present but in decline in 2-6-month-old infants later diagnosed with autism.

Deficits in eye contact have been a hallmark of autism since the condition's initial description. They are cited widely as a diagnostic feature and figure prominently in clinical instruments; however, the early onset of these deficits has not been known. Here we show in a prospective longitudinal study that infants later diagnosed with autism spectrum disorders (ASDs) exhibit mean decline in eye fixation from 2 to 6 months of age, a pattern not observed in infants who do not develop ASD. These observations mark the earliest known indicators of social disability in infancy, but also falsify a prior hypothesis: in the first months of life, this basic mechanism of social adaptive action--eye looking--is not immediately diminished in infants later diagnosed with ASD; instead, eye looking appears to begin at normative levels prior to decline. The timing of decline highlights a narrow developmental window and reveals the early derailment of processes that would otherwise have a key role in canalizing typical social development. Finally, the observation of this decline in eye fixation--rather than outright absence--offers a promising opportunity for early intervention that could build on the apparent preservation of mechanisms subserving reflexive initial orientation towards the eyes.

Assessing Binary Diagnoses of Bio-behavioral Disorders: The Clinical Relevance of Cohen's Kappa.

Cohen's (Educ Psychol Meth. 1960;23:37-40) kappa statistic has been criticized recently for providing low chance-corrected coefficients (<0.40) despite high levels of examiner agreement (e.g., ≥85%). The AC1 statistic (Series. 2002;2:1-9; BMC Med Res Methodol. 2013;13:61), the alpha statistic (J Clin Epidemiol. 1996;49:775-782), the B statistic (BMC Med Res Methodol. 2013;13:97), and the delta statistic (Commun Statist Theory Meth. 2008;37:760-772) were developed to "correct" this "problem." Each of these statistics produces inaccurate results because they either derive from levels of chance agreement that are incorrect (Gwet's AC1 statistic) or fail to correct for chance levels of agreement (the alpha, B, and delta approaches). Implications for diagnoses of psychiatric disorders are critically discussed. The importance of kappa is demonstrated in a number of clinical scenarios.

Rapid video-referenced ratings of reciprocal social behavior in toddlers: a twin study.

BACKGROUND: Reciprocal social behavior (RSB) is a developmental prerequisite for social competency, and deficits in RSB constitute a core feature of autism spectrum disorder (ASD). Although clinical screeners categorically ascertain risk of ASD in early childhood, rapid methods for quantitative measurement of RSB in toddlers are not yet established. Such measurements are critical for tracking developmental trajectories and incremental responses to intervention. METHODS: We developed and validated a 20-min video-referenced rating scale, the video-referenced rating of reciprocal social behavior (vrRSB), for untrained caregivers to provide standardized ratings of quantitative variation in RSB. Parents of 252 toddler twins [Monozygotic (MZ) = 31 pairs, Dizygotic (DZ) = 95 pairs] ascertained through birth records, rated their twins' RSB at two time points, on average 6 months apart, and completed two developmental measures, the Modified Checklist for Autism in Toddlers (M-CHAT) and the MacArthur Communicative Development Inventory Short Form (MCDI-s). RESULTS: Scores on the vrRSB were fully continuously distributed, with excellent 6-month test-retest reliability ([intraclass correlation coefficient] ICC = 0.704, p < .000). MZ twins displayed markedly greater trait concordance than DZ twins, (MZ ICC = 0.863, p < .000, DZ ICC = 0.231, p < .012). VrRSB score distributions were highly distinct for children passing versus failing the M-CHAT (t = -8.588, df = 31, p < .000), incrementally improved from 18-24 months, and were inversely correlated with receptive and expressive vocabulary on the MCDI-s. CONCLUSIONS: Like quantitative autistic trait ratings in school-aged children and adults, toddler scores on the vrRSB are continuously distributed and appear highly heritable. These ratings exhibited minimal measurement error, high inter-individual stability, and developmental progression in RSB as children matured from 18-24 months, supporting their potential utility for serially quantifying the severity of early autistic syndromes over time and in response to intervention. In addition, these findings inform the genetic-environmental structure of RSB in early typical development.

Two-year-olds with autism orient to non-social contingencies rather than biological motion.

Typically developing human infants preferentially attend to biological motion within the first days of life. This ability is highly conserved across species and is believed to be critical for filial attachment and for detection of predators. The neural underpinnings of biological motion perception are overlapping with brain regions involved in perception of basic social signals such as facial expression and gaze direction, and preferential attention to biological motion is seen as a precursor to the capacity for attributing intentions to others. However, in a serendipitous observation, we recently found that an infant with autism failed to recognize point-light displays of biological motion, but was instead highly sensitive to the presence of a non-social, physical contingency that occurred within the stimuli by chance. This observation raised the possibility that perception of biological motion may be altered in children with autism from a very early age, with cascading consequences for both social development and the lifelong impairments in social interaction that are a hallmark of autism spectrum disorders. Here we show that two-year-olds with autism fail to orient towards point-light displays of biological motion, and their viewing behaviour when watching these point-light displays can be explained instead as a response to non-social, physical contingencies--physical contingencies that are disregarded by control children. This observation has far-reaching implications for understanding the altered neurodevelopmental trajectory of brain specialization in autism.

Common genetic variants on 5p14.1 associate with autism spectrum disorders.

Autism spectrum disorders (ASDs) represent a group of childhood neurodevelopmental and neuropsychiatric disorders characterized by deficits in verbal communication, impairment of social interaction, and restricted and repetitive patterns of interests and behaviour. To identify common genetic risk factors underlying ASDs, here we present the results of genome-wide association studies on a cohort of 780 families (3,101 subjects) with affected children, and a second cohort of 1,204 affected subjects and 6,491 control subjects, all of whom were of European ancestry. Six single nucleotide polymorphisms between cadherin 10 (CDH10) and cadherin 9 (CDH9)-two genes encoding neuronal cell-adhesion molecules-revealed strong association signals, with the most significant SNP being rs4307059 (P = 3.4 x 10(-8), odds ratio = 1.19). These signals were replicated in two independent cohorts, with combined P values ranging from 7.4 x 10(-8) to 2.1 x 10(-10). Our results implicate neuronal cell-adhesion molecules in the pathogenesis of ASDs, and represent, to our knowledge, the first demonstration of genome-wide significant association of common variants with susceptibility to ASDs.

Toward innovative, cost-effective, and systemic solutions to improve outcomes and well-being of military families affected by autism spectrum disorder.

The burdens faced by military families who have a child with autism are unique. The usual challenges of securing diagnostic, treatment, and educational services are compounded by life circumstances that include the anxieties of war, frequent relocation and separation, and a demand structure that emphasizes mission readiness and service. Recently established military autism-specific health care benefits set the stage for community-viable and cost-effective solutions that can achieve better outcomes for children and greater well-being for families. Here we argue for implementation of evidence-based solutions focused on reducing age of diagnosis and improving access to early intervention, as well as establishment of a tiered menu of services, individualized to the child and family, that fit with the military ethos and system of health care. Absence of this new model of care could compromise the utility and sustainability of the autism-specific benefit.

Inhibition of eye blinking reveals subjective perceptions of stimulus salience.

Spontaneous eye blinking serves a critical physiological function, but it also interrupts incoming visual information. This tradeoff suggests that the inhibition of eye blinks might constitute an adaptive reaction to minimize the loss of visual information, particularly information that a viewer perceives to be important. To test this hypothesis, we examined whether the timing of blink inhibition, during natural viewing, is modulated between as well as within tasks, and also whether the timing of blink inhibition varies as a function of viewer engagement and stimulus event type. While viewing video scenes, we measured the timing of blinks and blink inhibition, as well as visual scanning, in a group of typical two-year-olds, and in a group of two-year-olds known for attenuated reactivity to affective stimuli: toddlers with Autism Spectrum Disorders (ASD). Although both groups dynamically adjusted the timing of their blink inhibition at levels greater than expected by chance, they inhibited their blinking and shifted visual fixation differentially with respect to salient onscreen events. Moreover, typical toddlers inhibited their blinking earlier than toddlers with ASD, indicating active anticipation of the unfolding of those events. These findings indicate that measures of blink inhibition can serve as temporally precise markers of perceived stimulus salience and are useful quantifiers of atypical processing of social affective signals in toddlers with ASD.

A biomarker-based solution for the limited access to early diagnosis and assessment of autism.

With the upsurge of community uptake in population-based early screening for autism, the main obstacle to increasing access to early treatment and intervention services is the extremely limited access to high quality diagnosis, specifically the shortage of expert clinicians. Diagnostic evaluation models deployed by academic centers of excellence, which typically require the investment of 6-10 hours by specialized multidisciplinary teams, is not a viable solution to the vast needs of communities, resulting in parents' "diagnostic odysseys" and delays, often of several years, for treatment, interventions and supports. Biomarker-based objective procedures for early diagnosis and assessment of autism are now available, clinically validated, and cleared for broad implementation by the US Food and Drug Administration (FDA). They are intended to increase access while maintaining high quality. Such solutions, however, will require change in entrenched models of diagnostic care, and aggressive prioritization of the needs of the community at large. If these innovations are successful, the number of children diagnosed in the first three years of life will double or triple. This will, in turn, require much greater investments in resources for treatment, including massive workforce training of providers capable of delivering community-viable caregiver-mediated interventions, and of early educators capable of serving autistic children in therapeutic inclusive preschool settings.

Con el aumento de la aceptación comunitaria de la detección temprana del autismo basada en la población, el principal obstáculo para aumentar el acceso al tratamiento temprano y a los servicios de intervención es el acceso extremadamente limitado a un diagnóstico de alta calidad, específicamente la escasez de médicos expertos. Los modelos de evaluación diagnóstica implementados por centros académicos de excelencia, que normalmente requieren la inversión de 6 a 10 horas por parte de equipos multidisciplinarios especializados, no son una solución viable para las vastas necesidades de las comunidades, lo que resulta en "odiseas diagnósticas" y retrasos, a menudo de gran importancia, para los padres varios años, para tratamiento, intervenciones y apoyos. Los procedimientos objetivos basados en biomarcadores para el diagnóstico temprano y la evaluación del autismo ya están disponibles, clínicamente validados y aprobados para su amplia implementación por la Administración de Alimentos y Medicamentos de EE. UU. (FDA). Su objetivo es aumentar el acceso manteniendo una alta calidad. Sin embargo, tales soluciones requerirán cambios en los modelos arraigados de atención de diagnóstico y una priorización agresiva de las necesidades de la comunidad en general. Si estas innovaciones tienen éxito, el número de niños diagnosticados en los primeros tres años de vida se duplicará o triplicará. Esto, a su vez, requerirá inversiones mucho mayores en recursos para el tratamiento, incluida la capacitación masiva de la fuerza laboral de proveedores capaces de brindar intervenciones comunitarias viables mediadas por cuidadores, y de educadores tempranos capaces de atender a niños autistas en entornos preescolares terapéuticos inclusivos.

Access to Part C, Early Intervention for children younger than 4 years evaluated for autism spectrum disorder.

LAY ABSTRACT: Health disparities are defined as preventable differences in the opportunities to achieve optimal health outcomes experienced by marginalized and underrepresented communities. For families with autistic children, health disparities limit accessing early intervention services-which have been found to improve quality of life and other outcomes. One specific early intervention service in the United States is Individuals with Disabilities Education Act, Part C Early Intervention programs, which are federally funded interventions for children birth-to-three with developmental delays. This study adds to this topic by examining which factors impact accessing Part C, Early Intervention services for children who were evaluated for autism. Results showed that only half of the sample received these services despite there being concerns about development for all children. In addition, results showed that those who identified as Black had decreased odds of having accessed Part C, Early Intervention compared to those who identified as White. These results suggest that there are disparities when it comes to accessing important early intervention services that may be negatively impacting the Black autistic community.

Neural signatures of autism.

Functional magnetic resonance imaging of brain responses to biological motion in children with autism spectrum disorder (ASD), unaffected siblings (US) of children with ASD, and typically developing (TD) children has revealed three types of neural signatures: (i) state activity, related to the state of having ASD that characterizes the nature of disruption in brain circuitry; (ii) trait activity, reflecting shared areas of dysfunction in US and children with ASD, thereby providing a promising neuroendophenotype to facilitate efforts to bridge genomic complexity and disorder heterogeneity; and (iii) compensatory activity, unique to US, suggesting a neural system-level mechanism by which US might compensate for an increased genetic risk for developing ASD. The distinct brain responses to biological motion exhibited by TD children and US are striking given the identical behavioral profile of these two groups. These findings offer far-reaching implications for our understanding of the neural systems underlying autism.

Translating advances in developmental social neuroscience into greater access to early diagnosis in autism spectrum disorder.

Early identification and diagnosis of autism spectrum disorder (ASD) is necessary to promote access to early treatment, a critical factor in optimizing children's lifetime outcomes. And yet, diagnosis is often late, delaying interventions to a time in which symptoms have aggravated and communication skills already show impairing differences. This review illustrates progress in developmental social neuroscience that shows promise in generating novel tools for objective and cost-effective early diagnosis of ASD. We focus on research of social visual engagement, which is the way infants and toddlers look at and learn from their social environment. Moment-by-moment quantification of social visual engagement is yielding measures that are beginning to approximate best-practice procedures used by experienced clinicians in the assessment of young children. This progress and potential solutions have public health import ance because experienced clinicians are limited in number, and specialized clinical assessment services tend to be lengthy, costly, and plagued by extended wait time, all of which contributing to limited access, particularly in the case of low-resource families. The research reviewed here illustrates a wider effort to advance biomarker-based measurements intended to develop better and more efficient tools and procedures for screening, diagnosing and monitoring treatment response in children with ASD. The advent of such tools could increase access to early diagnostic services and promote efficiencies in early treatment delivery, with the ultimate goal of ensuring that children with ASD are afforded the services they need to thrive.

La identificación y el diagnóstico temprano del trastorno del espectro autista (TEA) son necesarios para promover el acceso al tratamiento temprano, un factor crítico para optimizar los resultados de por vida de los niños. Y, sin embargo, el diagnóstico suele llegar tarde, lo que retrasa las intervenciones hasta un momento en el que los síntomas se han agravado y las habilidades de comunicación ya muestran diferencias perjudiciales. Esta revisión ilustra el progreso en la neurociencia social del desarrollo que se muestra prometedora en la generación de herramientas novedosas para el diagnóstico temprano objetivo y rentable de los TEA. Hacemos énfasis en la investigación del compromiso visual social, que es la forma en que los bebés y los niños pequeños miran y aprenden de su entorno social. La cuantificación momento a momento del compromiso visual social está generando medidas que comienzan a aproximarse a los procedimientos de mejores prácticas utilizados por médicos experimentados en la evaluación de niños pequeños. Este progreso y las posibles soluciones tienen importancia para la salud pública porque los médicos con experiencia son limitados en número y los servicios de evaluación clínica especializados tienden a ser largos, costosos y están plagados de tiempo de espera prolongado, todo lo cual contribuye a un acceso limitado, particularmente en el caso de familias con bajos recursos. La investigación revisada aquí ilustra un esfuerzo más amplio para avanzar en las mediciones basadas en biomarcadores destinadas a desarrollar herramientas y procedimientos mejores y más eficientes para la detección, el diagnóstico y el seguimiento de la respuesta al tratamiento en niños con TEA. El advenimiento de tales herramientas podría aumentar el acceso a los servicios de diagnóstico temprano y promover la eficiencia en la entrega del tratamiento temprano, con el objetivo final de garantizar que los niños con TEA reciban los servicios que necesitan para prosperar.