Journal of Neurodevelopmental Disorders

Phelan-McDermid syndrome (PMS) is a genetic neurodevelopmental disorder caused by a microdeletion within chromosome 22q13.3 1-6, and accounts for [~]1-3% of cases of autism spectrum disorders (ASD). Individuals with PMS typically present with neonatal hypotonia, severe speech delay, intellectual disability, motor impairments, and autism-related features, although additional manifestations such as epilepsy, sleep disturbances, and developmental regression are common. As in ASD, there is considerable heterogeneity in cognitive and behavioral impairments in PMS, making it difficult to determine which features arise directly from SHANK3/Shank3 deficiency and how deficits manifest across development. In the present study, we transferred the targeted Shank3 mutation, previously characterized on the Sprague Dawley background, onto the Long-Evans strain and performed a longitudinal behavioral assessment of Shank3-deficient rats from infancy to adulthood. The rats were evaluated for delays in early sensory and motor development, and ultrasonic vocalizations as neonates, social behavior, short term memory and gait as juveniles, and cognitive-executive dysfunction using a touchscreen-based visual discrimination and reversal learning task as adults. Despite profound reductions and/or complete loss of Shank3 protein expression, heterozygous and homozygous male and female rats showed normal physical and neurological reflexes across development, yet female Shank3 knockout pups showed a selective reduction in distress-associated ultrasonic vocalizations. As juveniles, subtle abnormalities emerged in short-term memory and limb coordination, while social preference for novelty and recognition was normal. Prominent behavioral abnormalities were observed in adults characterized by rapid and error-prone responding to visual stimuli during discrimination learning and reversal. These data suggest that rats with complete or partial Shank3 deficiency produce a selective behavioral profile in which high-order cognitive dysfunction is more pronounced than deficits in basic sensorimotor or select social behaviors. More broadly, these findings highlight executive dysfunction as a key consequence of the loss of Shank3. For the first time, we report the loss of Shank3 expression on a Long-Evans background strain as a valuable translational tool for investigating cognitive dysfunction and therapeutic windows in Shank3-associated disorders.

Background3q29 deletion syndrome (3q29del) is associated with a significantly increased risk for neurodevelopmental and neuropsychiatric phenotypes. Mild to moderate intellectual disability (ID) is common in this population, and previous work by our team identified substantial deficits in adaptive behavior. However, the full profile of adaptive function in 3q29del has not been described, nor has it been compared to other genomic syndromes associated with elevated risk for neurodevelopmental and neuropsychiatric phenotypes. MethodsIndividuals with 3q29del (n=32, 62.5% male) were evaluated using the Vineland Adaptive Behavior Scales, Third Edition, Comprehensive Parent/Caregiver Form (Vineland-3). We explored the relationship between adaptive behavior and cognitive function, executive function, and neurodevelopmental and neuropsychiatric comorbidities in our 3q29del study sample, and we compared subjects with 3q29del to published data on Fragile X syndrome, 22q11.2 deletion syndrome, and 16p11.2 deletion and duplication syndromes. ResultsIndividuals with 3q29del had global deficits in adaptive behavior that were not driven by specific weaknesses in any given domain. Individual neurodevelopmental and neuropsychiatric diagnoses had a small effect on adaptive behavior, and the cumulative number of comorbid diagnoses was significantly negatively associated with Vineland-3 performance. Both cognitive ability and executive function were significantly associated with adaptive behavior, and executive function was a better predictor of Vineland-3 performance than cognitive ability. Finally, the severity of adaptive behavior deficits in 3q29del was distinct from previously published data on comparable genomic disorders. ConclusionsIndividuals with 3q29del have significant deficits in adaptive behavior, affecting all domains assessed by the Vineland-3. Executive function is a better predictor of adaptive behavior than cognitive ability in this population and suggests that interventions targeting executive function may be an effective therapeutic strategy.

Some toddlers with autism spectrum disorder (ASD) have mild social symptoms and developmental improvement in skills, but for others, symptoms and abilities are moderately or even severely affected. Those with profound autism have the most severe social, language, and cognitive symptoms and are at the greatest risk of having a poor developmental outcome. The little that is known about the underlying biology of this important profound autism subtype, points clearly to embryonic dysregulation of proliferation, differentiation and neurogenesis. Because it is essential to gain foundational knowledge of the molecular biology associated with profound, moderate, and mild autism clinical subtypes, we used well-validated, data-driven patient subtyping methods to integrate clinical and molecular data at 1 to 3 years of age in a cohort of 363 ASD and controls representative of the general pediatric population in San Diego County. Clinical data were diagnostic, language, cognitive and adaptive ability scores. Molecular measures were 50 MSigDB Hallmark gene pathway activity scores derived from RNAseq gene expression. Subtyping identified four ASD, typical and mixed diagnostic clusters. 93% of subjects in one cluster were profound autism and 93% in a different cluster were control toddlers; a third cluster was 76% moderate ability ASD; and the last cluster was a mix of mild ASD and control toddlers. Among the four clusters, the profound autism subtype had the most severe social symptoms, language, cognitive, adaptive, social attention eye tracking, social fMRI activation, and age-related decline in abilities, while mild autism toddlers mixed within typical and delayed clusters had mild social symptoms, and neurotypical language, cognitive and adaptive scores that improved with age compared with profound and moderate autism toddlers in other clusters. In profound autism, 7 subtype-specific dysregulated gene pathways were found; they control embryonic proliferation, differentiation, neurogenesis, and DNA repair. To find subtype-common dysregulated pathways, we compared all ASD vs TD and found 17 ASD subtype-common dysregulated pathways. These common pathways showed a severity gradient with the greatest dysregulation in profound and least in mild. Collectively, results raise the new hypothesis that the continuum of ASD heterogeneity is moderated by subtype-common pathways and the distinctive nature of profound autism is driven by the differentially added profound subtype-specific embryonic pathways.

ImportanceMotor skill impairments affect up to 87% of children with autism spectrum disorder (ASD) and are associated with greater severity of repetitive behaviors. Yet, most research examining this relationship has treated ASD as a unitary condition. Understanding whether motor-behavior relationships differ by genetic etiology could inform stratified approaches to ASD research and clinical care. ObjectiveTo determine whether the relationship between motor function and restricted and repetitive behaviors (RRBs) differs between children with monogenic forms of ASD (SHANK3, DYRK1A, or SCN2A variants) and children with idiopathic ASD. Design, Setting, and ParticipantsMatched cohort cross-sectional study using data from the Simons Foundation Powering Autism Research for Knowledge (SPARK) database. Children with loss-of-function variants in SHANK3, DYRK1A, or SCN2A were matched to children with idiopathic autism and intellectual disability. Main Outcomes and MeasuresMotor function was assessed using the Developmental Coordination Disorder Questionnaire (DCDQ). Repetitive behaviors were assessed using the Repetitive Behavior Scale-Revised (RBS-R), with subscales categorized as lower-order (stereotyped, self-injurious) or higher-order (compulsive, ritualistic, sameness, restricted interests). The primary analysis compared motor-RRB correlations between groups. ResultsThe sample included 93 children with monogenic autism (SHANK3, n=34; DYRK1A, n=46; SCN2A, n=13) and 787 matched children with idiopathic ASD. In idiopathic ASD, motor function was negatively correlated with RRBs (r = -0.156); in monogenic ASD, this reversed to a positive correlation (r = +0.185; {Delta}r = 0.341, P = 0.002). This reversal was specific to higher-order RRBs (idiopathic r=-0.106; monogenic r=+0.234; {Delta}r=0.339, 95% CI 0.124-0.535, P=0.002) and was not observed for lower-order RRBs ({Delta}r=0.212, P=0.05). All three genes showed positive correlations (SHANK3 r=+0.033; DYRK1A r=+0.262; SCN2A r=+0.623) with no significant heterogeneity (P=0.153). Conclusions and RelevanceThe relationship between motor function and repetitive behaviors differs by genetic etiology, with children with monogenic ASD showing a positive motor-RRB correlation specific to higher-order behaviors, opposite to the negative correlation observed in idiopathic ASD. This reversal was consistent across three molecularly distinct genes. These findings support stratifying autism research and clinical care by genetic etiology. KEY POINTSO_ST_ABSQuestionC_ST_ABSDoes the relationship between motor function and restricted and repetitive behaviors (RRBs) differ between children with autism spectrum disorder (ASD) attributable to SHANK3, DYRK1A, or SCN2A variants and children with idiopathic ASD? FindingsWe conducted a matched cohort cross-sectional study comparing correlations between motor function and RRBs in children with monogenic ASD versus children with idiopathic ASD and intellectual disability. Motor function was negatively correlated with RRBs in children with idiopathic ASD but positively correlated in children with monogenic ASD. MeaningGenetic variants may alter behavioral organization, supporting the value of stratifying populations of individuals with ASD by genetic etiology in both research and clinical care.

BackgroundThe 1.6 Mb 3q29 deletion is associated with neurodevelopmental and neuropsychiatric phenotypes, including a 19-fold increased risk for autism spectrum disorder (ASD). Previous work by our team identified elevated social disability in this population via parent-report questionnaires. However, clinical features of ASD in this population have not been explored in detail. Methods31 individuals with 3q29 deletion syndrome (3q29del, 61.3% male) were evaluated using two gold-standard clinical ASD evaluations: the Autism Diagnostic Observation Schedule, Second Edition (ADOS-2) and the Autism Diagnostic Interview, Revised (ADI-R). Four matched comparators for each subject were ascertained from the National Database for Autism Research. Item-level scores on the ADOS-2 and ADI-R were compared between subjects with 3q29del and matched comparators. ResultsSubjects with 3q29del and no ASD (3q29del-ASD) had greater evidence of social disability compared to typically developing (TD) comparison subjects across the ADOS-2. Subjects with 3q29del and ASD (3q29del+ASD) were largely indistinguishable from non-syndromic ASD (nsASD) subjects on the ADOS-2. 3q29del+ASD performed significantly better on social communication on the ADI-R than nsASD (3q29+ASD mean = 11.36; nsASD mean = 15.70; p = 0.01), and this was driven by reduced deficits in nonverbal communication (3q29+ASD mean = 1.73; nsASD mean = 3.63; p = 0.03). 3q29del+ASD reported significantly later age at first two-word phrase compared to nsASD (3q29del+ASD mean = 43.89 months; nsASD mean = 37.86 months; p = 0.01). However, speech delay was not related to the improved nonverbal communication in 3q29del+ASD. LimitationsThere were not enough TD comparators with ADI-R data in NDAR to include in the present analysis. Additionally, our relatively small sample size made it difficult to assess race and ethnicity effects. Conclusions3q29del is associated with significant social disability, irrespective of ASD diagnosis. 3q29del+ASD have similar levels of social disability to nsASD, while 3q29del-ASD have significantly increased social disability compared to TD individuals. However, social communication is reasonably well-preserved in 3q29del+ASD relative to nsASD. It is critical that verbal ability and social disability be examined separately in this population to ensure equal access to ASD and social skills evaluations and services.

Infants born preterm are at a significantly higher likelihood of having autism spectrum disorder (ASD). Preterm birth and ASD are both associated with neurological differences, notably autonomic nervous system (ANS) dysfunction, pointing to preterm ANS dysfunction as a potential pathway to ASD, particularly in VPT infants. In this study, a subset of very preterm (VPT) infants enrolled in a large, multisite clinical trial were enrolled in this study at birth (N=20). Continuous measures of minute-by-minute thermal gradients, defined by the difference between central and peripheral temperatures, and hour-by-hour abnormal heart rate characteristics (HRCs) were collected from birth-28 days (>40,000 samples/infant). Following NICU discharge, standardized measures of cognition, language, and motor skills were collected at adjusted ages 6, 9, and 12 months. At 12 months, assessments of social communication and early ASD symptoms were administered. Results suggest significant ASD concerns for half of the sample by 12 months of age. Neonatal abnormal HRCs were strongly associated with 12-month ASD symptoms (r=0.81, p<.01), as was birth gestational age (GA), birth weight (BW), and abnormal negative thermal gradients. ANS measures collected in the first month of neonatal life, more than a year prior to the ASD evaluation, were surprisingly strong predictors of ASD. This study highlights complementary ANS measures that describe how ANS dysfunction, likely resulting from an imbalance between the parasympathetic and sympathetic systems, may impact very early regulatory processes for neonates who later develop ASD. This finding offers a promising avenue for researching ANS-related etiological mechanisms and biomarkers of ASD.

Overgrowth intellectual disability syndromes (OGIDs) caused by mutations in the PI3K-AKT-MTOR pathway present significant neurobehavioral challenges. While PTEN Hamartoma Tumor Syndrome (PHTS) has been behaviorally characterized, Smith-Kingsmore Syndrome (SKS) has not, limiting our understanding of shared and unique features across OGIDs. We conducted comprehensive neurobehavioral assessments in 17 individuals with SKS and compared them to previously characterized cohorts with PHTS (n=74), macrocephaly-associated autism (n=33), and healthy controls (n=32). Assessments included standardized measures of motor coordination, adaptive functioning, social interaction, and executive functioning. We performed genotype-phenotype correlation analyses and developed diagnostic classification models using recursive partitioning. Individuals with SKS showed significant impairments across multiple domains compared to controls. Compared to the PTEN-ASD group, SKS individuals demonstrated particularly severe deficits in motor coordination and adaptive functioning, while executive functioning and behavioral regulation were similarly impaired. Novel clinical features were identified, including immune dysregulation and chronic constipation in SKS, and notably high rates of neonatal teeth (44.7%) in PHTS. Diagnostic classification models incorporating both behavioral and medical features achieved above-chance accuracy in distinguishing between conditions, with neonatal teeth emerging as a key distinguishing feature for PHTS. Domain-specific analyses showed variants in the PTEN phosphatase domain were associated with more severe social and executive function deficits compared to C2 domain variants. Correlation analyses between variant pathogenicity scores and clinical measures revealed limited consistent associations, though Combined Annotation Dependent Depletion (CADD) scores showed stable correlations with sensory processing measures across cohorts. Our findings establish distinct neurobehavioral profiles between SKS and PHTS, suggesting different impacts of MTOR versus PTEN mutations on neural circuit development. The identification of novel phenotypic features expands the clinical spectrum of these disorders and provides new diagnostic markers. The limited predictive value of variant pathogenicity scores for neurobehavioral outcomes emphasizes the need for comprehensive individual assessments. These results provide a foundation for developing targeted interventions while highlighting the complexity of genotype-phenotype relationships in PI3K-AKT-MTOR pathway disorders.

Abstract Background & Aims: Language development in autism is heterogeneous and strongly predicts later functioning. The balance between receptive and expressive abilities and their developmental trajectories, however, remains poorly understood. While some autistic children exhibit a relative expressive advantage (ExpAdv), others show receptive advantage (RecAdv) or a balanced profile. Prior studies report inconsistent findings and are often limited by cross-sectional designs and small samples. The present study aimed to (1) describe longitudinal trajectories of receptive and expressive language in autistic and typically developing (TD) children; (2) classify children into ExpAdv, Balanced, and RecAdv profiles across early childhood; and (3) examine the stability and transitions of these profiles over time, including associated clinical features. Methods: We analyzed 1,174 longitudinal time points from 318 autistic children and 294 time points from 108 TD children (1.2-5.8 years) from the Geneva Autism Cohort. Receptive and expressive language were assessed with the Mullen Scales of Early Learning. Receptive-expressive balance was quantified as the ratio of receptive to expressive age equivalent scores, classifying children into ExpAdv, Balanced, and RecAdv profiles using adapted cut-offs. Mixed-effects models examined developmental trajectories, and Sankey diagrams visualized profile transitions. Autism features and adaptive behavior were compared across profiles. Results: Autistic children displayed lower expressive and receptive language than TD peers, with receptive abilities exceeding expressive skills in both groups. Overall, 30-35% of autistic children were classified as ExpAdv at 18-36 months, declining to ~12% by 48-54 months, while Balanced and RecAdv profiles became more prevalent with age. ExpAdv was associated with slower verbal and non-verbal developmental gains. Stability was highest for Balanced and RecAdv profiles (50-60%), whereas ExpAdv often transitioned to Balanced. Autistic children with stable ExpAdv profiles were more often female, less likely to receive early intervention, and showed weaker adaptive communication. Conclusions: Receptive-expressive language profiles in autistic children are dynamic. ExpAdv profile is more frequent in younger autistic children, less stable, and linked to slower verbal and non-verbal development and higher autism severity. Implications: ExpAdv may represent an early marker of autism associated with slower expressive and receptive language growth. Longitudinal monitoring of receptive and expressive skills is essential, as transitions toward Balanced or RecAdv profiles are associated with improved developmental outcomes. Early intervention before age three may facilitate transitions toward Balanced or RecAdv profiles, supporting more favorable language development and long-term outcomes. Keywords: autism; early childhood; longitudinal design; expressive language; receptive language; language profile; early intervention; language gap; discrepant profiles

IntroductionFragile X Syndrome (FXS), caused by Fmr1 mutations, is linked to cognitive and behavioral differences, including altered social interactions. Most mouse studies focus on adults, despite human research showing critical developmental changes in childhood and adolescence. We examined social behavior in juvenile male and female Fmr1 knockout (KO) mice as well as heterozygous (HET) females. We further assessed cortical activity in KO females to better understand early phenotypes. MethodsJuvenile mice of both sexes and genotypes were paired in same-sex, novel dyads for 10-minute interactions. Key social behaviors such as head, anogenital, and body sniffing, and physical touch, as well as distance travelled, were analyzed with a marker-less tracking software. Frontal-parietal EEG recordings were collected from wild-type (WT) and KO females in home cage and social contexts to analyze power spectra across frequency bands. ResultsHET and KO females engaged in more frequent but shorter interaction events compared to WT females, with HET females showing the highest counts. Males displayed similar trends when comparing KO and WT. Males engaged in overall higher interaction events than females. EEG analyses revealed altered oscillatory activity in KO females compared to WT females, especially within theta, alpha, and beta bands, most prominently during the early interaction phase. Locomotor activity correlated weakly with head/anogenital sniffing but more strongly with body sniffing and touch. DiscussionThese findings suggest that Fmr1-related differences in juvenile social behavior are sex-dependent and associated with cortical oscillatory changes. Characterizing these early phenotypes in both sexes allows us to further understand FXS development and informs potential routes for early intervention. Key PointsO_LIFragile X Syndrome (FXS), the leading inherited cause of autism, is associated with disruptions in social behavior. C_LIO_LIWhile social phenotypes are relatively well described in adult mouse models of FXS, juvenile manifestations remain poorly understood. C_LIO_LISocial behavior was assessed in juvenile male and female Fmr1 knockout (KO), heterozygous (HET, female only), and wildtype (WT) mice, and frontal-parietal EEG recordings were collected from WT and KO females. C_LIO_LIHET and KO females exhibited more frequent but shorter social interactions than WT females, with HET showing the greatest number of events. Males showed similar patterns when comparing KO and WT. Males engaged in higher overall interaction events than females. EEG recordings revealed altered oscillatory activity in KO compared to WT females, most pronounced during the early phase of social encounter. C_LIO_LIThese findings reveal sex- and genotype-dependent differences in juvenile social behavior and cortical activity, highlighting the importance of studying juvenile development in FXS. C_LI

Facial attractiveness plays a central role in first impressions, social interactions, and romantic relationships, yet remains difficult to quantify objectively due to its subjective and socially shaped nature. In the present study, we examined whether facial attractiveness and its modulation by social information can be captured using functional infrared thermal imaging (fITI). Participants rated the attractiveness of faces that were randomly preceded by an autism label. Although such labels influenced explicit attractiveness judgments, particularly among male participants, they did not modulate facial thermal responses. Instead, nose temperature systematically increased or decreased when participants rated faces as attractive or unattractive, respectively. Notably, temperature differences emerged several seconds after image onset, and for female faces, mean attractiveness ratings positively correlated with changes in nose temperature. Together, these findings reveal a dissociation between socially shaped explicit evaluations and autonomic physiological responses, highlighting the potential of fITI as a fully non-invasive tool for capturing implicit affective engagement with facial attractiveness.

People with autism spectrum disorder (ASD) frequently exhibit challenging behaviors throughout the lifespan, which can have pervasive effects on quality of life. Challenging behaviors have been shown to change over time as a function of various individual-level factors (e.g., cognitive ability), yet research is primarily limited to parent-reported measures. To expand upon this work, the present study aimed to examine trajectories of teacher- and parent-reported challenging behaviors (i.e., hyperactivity, irritability, social withdrawal) and to test whether predictors including ASD features, verbal intelligence quotient, and consistency in reporter impact these trajectories among individuals with ASD or non-spectrum delays from ages 9 to 18. Multilevel models revealed that, according to both teacher and parent report, participants showed the greatest improvement in hyperactivity, less but still notable improvement in irritability, and stable levels of social withdrawal over time. Higher cognitive ability and fewer ASD features emerged as important individual differences related to fewer challenging behaviors. The multi-informant perspective and longitudinal design provide novel insight into the manifestations of these challenging behaviors across different contexts and across time. Findings highlight the importance of addressing challenging behaviors as these behaviors tend to persist throughout development in both home and school contexts, especially for children with particular diagnostic and cognitive profiles. Lay SummaryAccording to both teacher and parent report, youth with autism showed the greatest improvement in hyperactivity, less but still notable improvement in irritability, and stable levels of social withdrawal from school-age to adolescence. Fewer autism features and greater cognitive ability were related to fewer challenging behaviors. This studys use of multiple reporters (e.g., teachers and parents) across time provided insight into the persistence of challenging behaviors in the home and school settings and across development.

Although language acquisition delays are frequently observed in children with autism spectrum disorder (autism), our current understanding of the neurobiological mechanisms underlying language development in autism is sparse. Previous studies have found resting-state electroencephalography (EEG) power to be associated with language abilities in autistic children. However, longitudinal studies examining resting-state EEG phase coherence in relation to language development in preschool-aged children with autism are limited. This study aimed to characterize age- and group-related changes in whole-brain coherence in neurotypical children and in autistic children with and without language delay. Resting-state EEG and language data were collected at 2, 3, and 4 years of age. Peak phase coherence within the alpha band (6-11 Hz) was calculated at each timepoint and differences in the developmental trajectory of peak alpha coherence (PAC) were analyzed. In neurotypical children, PAC increased between 2 and 4 years of age. In contrast, PAC did not significantly change with age in children with autism. However, when examining autistic children based on language delay status, PAC increased with age in autistic children without language delay, but not in children with language delay. Exploratory analysis revealed evidence for an interaction between PAC and age, suggesting that the direction of the association between PAC and VDQ varied across age. Overall, these results support previous findings of altered oscillatory connectivity in autism and suggest that differences become apparent early in development. Importantly, phase coherence may not only differentiate diagnostic groups but also capture meaningful variability within the autism group. Future research should further investigate the use of EEG coherence as a biomarker of language development in autism.

Autism spectrum disorder (ASD) is a highly heritable neurodevelopmental disorder. Sequencing analyses have identified 185 ASD-associated genes, which implicate neurons, but the specific brain regions through which these neurons influence neurodevelopment remain unclear. Here, we integrate over one million single-cell RNA sequencing profiles from 20 regions of the developing human brain (4-23 post-conceptual weeks) using a new framework, STARMAPS (Sparse Task-specific Analysis for Revealing Molecular Associations in Particular Single-cell datasets). STARMAPS accounts for coordinated regional and developmental perturbations in gene expression, enabling robust cross-region comparison. We replicate prior findings that ASD-associated genes are enriched in excitatory neurons during mid-fetal development, and we extend these results to reveal distinct spatial signatures. Across 26 excitatory neuron subtypes, six clusters showed significant enrichment for ASD-associated genes. These clusters localize to both cortical and subcortical regions, including the motor, temporal, and visual cortex, as well as the thalamus and hypothalamus. Our findings support a major role for excitatory neurons across distributed brain circuits, implicating previously underappreciated subcortical structures in ASD etiology. By providing a statistically rigorous framework for spatiotemporal integration of single-cell data, STARMAPS enables refined mapping of molecular vulnerability across the developing human brain.

PurposeThough co-occurring structural language impairment (LI) in autism is common and predicts long-term outcomes, little is known about LI in autism beyond childhood. One challenge to closing this gap is that there is no consensus definition of LI. This study focuses on LI in autistic adolescents and young adults, asking to what extent clinical classification differs by definition and examining performance across language measures, nonverbal intelligence (NVIQ), and autism traits. MethodParticipants (N = 75; ages 13-30) varying in levels of autism traits completed norm-referenced measures of overall expressive language, overall receptive language, receptive vocabulary, expressive vocabulary, nonword repetition, and NVIQ. Scores were compared to epidemiological definitions for LI varying in criteria and cutoffs from -1 SD to -1.5 SD. Data were analyzed using descriptives and clustering. ResultsMore stringent definitions yielded a greater proportion of participants meeting LI criteria, and more stringent cutoffs for LI yielded greater overall consistency in clinical classification across individual language measures, but there was no one-to-one ratio between cutoff and clinical classification. Clustering indicated three profiles differentiated on the basis of language and nonverbal cognitive skills, but each cluster was heterogeneous. Individual performance also varied across language measures. DiscussionFindings support multi-domain approaches to characterizing language skills in autistic adolescents and adults, including those with LI. Future work is needed to understand language skills in autism beyond childhood and how to develop effective assessment practices.

Language development, a core pillar of social communication, has variable trajectories in autism that include a regression or loss of skills in roughly 20% of autistic individuals. Language regression is most frequently identified through parent report but can also be observed as a decrease in raw scores on a repeated language assessment (measure-defined). Later language outcomes after regression have been observed to be highly variable, but not lower than children without a language regression. The current study explores rates of parent-reported and measure-defined language regression in a large sample of infants at high familial likelihood of autism due to having an older autistic sibling. Among all participants at high familial likelihood for autism (n=428), parent-reported regression was observed in 2.8% (n=12) and was associated with 2.77 times higher odds of receiving an autism diagnosis. Measure-defined regression was observed in 8% (n=36) and was associated with 1.21 times higher odds of autism diagnosis. These rates of regression are expectedly lower than estimates collected in autistic samples. Neither of these elevated odds was statistically significant and there was low concordance between these groups with only one participant present in both. Nearest-neighbor comparison samples of non-autistic infants at high and low likelihood for autism without language regression were selected to assess differences in language growth trajectories associated with regression. Infants with parent-reported language regression showed comparable language development to a matched high-likelihood sample while infants with measure-defined language regression showed slower overall language development than matched peers. Taken together, our results show that parent-report and direct measurement of regression capture unique aspects of child language development that may not be predictive of an autism diagnosis but may indicate delayed language growth in early toddlerhood. These language outcomes support previous findings of wide heterogeneity among those with regression and continued language growth after loss of skills. Key PointsO_LILanguage regression can be captured through parent-report or decrease in raw scores on repeated language assessment and is reported in approximately 20% of autistic toddlers. C_LIO_LIMost research on language regression uses retrospective report of regression in autistic children, but this study prospectively examines regression in toddlers at high familial likelihood for autism who do and do not receive later diagnoses. C_LIO_LIParent-reported and measure-defined regression in this high-likelihood sample have low concordance indicating that these may be different events in language development. C_LIO_LIThe presence of language regression was not associated with significantly higher odds of receiving an autism diagnosis. C_LIO_LIChildren who exhibit language regression continue growing and developing language and those with parent-reported regression display comparable language skills to children without language regression at three years of age. C_LI

Background: Autism Spectrum Disorder (ASD) and Attention-Deficit/Hyperactivity Disorder (ADHD) exhibit high clinical overlap, but categorical diagnostic boundaries obscure their shared, dynamic physiological vulnerabilities during real-world sensory processing. Methods: We analyzed multimodal eye-tracking synchrony in a large transdiagnostic pediatric cohort (N = 2,026) during naturalistic viewing of four distinct media paradigms. A novel 2D complex correlation framework captured gaze inter-subject correlation (ISC) magnitude and spatiotemporal phase divergence, while 1D pupil ISC measured autonomic arousal synchrony. Linear models evaluated dimensional (RDoC) and categorical (2x2 ANCOVA) diagnostic frameworks alongside rigorous medication and severity controls. Results: Dimensional models revealed a domain-general vulnerability: autistic traits independently predicted widespread reductions across gaze synchrony in all media contexts, and pupillary synchrony in narrative-driven contexts, whereas continuous ADHD traits showed minimal independent effects. In contrast, severe spatiotemporal misalignment (phase divergence) did not scale dimensionally but emerged strictly at clinical boundaries, reflecting highly idiosyncratic spatial locking in isolated ASD. Furthermore, categorical models demonstrated a robust, non-additive interaction: the clinical co-occurrence of ADHD paradoxically buffered against this severe spatiotemporal decoupling. Crucially, this protective phenotype was localized strictly to character-driven social narratives and remained highly significant after rigorously adjusting for daily stimulant medication, outlier instability, and baseline autism trait severity. Conclusions: These findings validate model-free physiological synchrony as a candidate transdiagnostic biomarker. Rather than compounding impairment, comorbid ASD and ADHD reflect competing, non-additive neurocognitive strategies that yield distinct, context-dependent visual phenotypes.

Sleep problems and sensory over-responsivity (SOR) are common, co-occurring, and early-emerging features of Autism Spectrum Disorder (ASD). Yet, the early neural mechanisms underlying this relationship remain unclear. Here, we used resting-state fMRI data from the Infant Brain Imaging Study (IBIS) to examine how brain connectivity at 6 months may relate to parent-reported measures of sleep-onset problems and SOR in infants at varying familial likelihood for ASD. The right anterior insula was used in seed-based analyses to investigate Salience Network (SN) connectivity to cortical and cerebellar regions of interest previously implicated in sleep disruption, sensory processing challenges, and ASD. Infants at high (HL) and low (LL) likelihood for ASD displayed divergent patterns of SN connectivity with sensorimotor cortex, as well as cerebellar regions involved in sensorimotor processing and higher-order functions. Furthermore, stronger SN connectivity with sensorimotor cortices and cerebellar regions was associated with worse sleep-onset problems and SOR in HL infants. In contrast, stronger SN-cerebellar connectivity was related to fewer sleep-onset problems and SOR in LL infants. Our findings indicate that altered SN connectivity may result in over-attribution of attention to sensory stimuli and highlight aberrant sensory prediction learning, which may underlie worse sleep problems and higher SOR in HL infants.

PurposeThis study aimed to examine the association between age-specific sleep sufficiency and autism spectrum disorders (ASD) among U.S. children aged 6-17 years. MethodsData were gathered from the 2022-2023 National Survey of Childrens Health (NSCH), including 63,866 children. Sleep sufficiency was defined based on age-specific guidelines from the American Academy of Sleep Medicine. Descriptive statistics, incidence risk ratios (IRRs), and adjusted logistic regression models were used to assess associations between ASD and key predictors. Stratified models by sex and BMI were conducted to explore effect modification. Additionally, a machine learning model was developed to predict the adjusted probability of ASD risk. ResultsChildren with insufficient sleep had a significantly higher incidence of ASD (5.16%) compared to those with sufficient sleep (4.05%) (p < 0.001). In adjusted models, sufficient sleep was associated with lower odds of ASD (OR = 0.78; 95% CI: 0.72-0.85; p < 0.001). Stratified analyses showed a protective effect in both males (OR = 0.78; 95% CI: 0.71-0.86) and females (OR = 0.80; 95% CI: 0.68-0.93), more pronounced in males. Machine learning analysis revealed that females with sufficient sleep and age below 14 years exhibited the lowest probability of ASD, whereas males aged 8 to 14 years with insufficient sleep demonstrated the highest likelihood of ASD risk. ConclusionThese results suggest that sufficient age-specific sleep is significantly associated with reduced odds of ASD, particularly in male children. Findings highlight the importance of sleep as a potentially modifiable factor in ASD risk and support targeted public health interventions.

Background3q29 deletion syndrome (3q29del) is a rare ([~]1:30,000) genomic disorder associated with a wide array of neurodevelopmental and psychiatric phenotypes. Prior work by our team identified clinically significant executive function deficits in 47% of individuals with 3q29del; however, the nuances of executive function in this population have not been described. MethodsWe used the Behavior Rating Inventory of Executive Function (BRIEF) to perform the first in-depth assessment of real-world executive functioning in a cohort of 32 individuals with 3q29del (62.50% male, mean age=14.50{+/-}8.26 years). High-resolution structural magnetic resonance imaging was performed on a subset of participants (n=24). ResultsWe found global deficits in executive function; individuals with 3q29del scored significantly higher than the population mean on the BRIEF Global Executive Composite (GEC) and all subscales. 81.25% of study subjects (n=26) scored in the clinical range on at least one BRIEF subscale. BRIEF GEC T scores were significantly higher among 3q29del participants with a diagnosis of ADHD, and BRIEF GEC T scores were significantly associated with schizophrenia spectrum symptoms as measured by the SIPS. The BRIEF-2 ADHD Form accurately (sensitivity=86.70%) classified individuals with 3q29del based on ADHD diagnosis status, highlighting its potential use as a screener for ADHD in this population. BRIEF GEC T scores were significantly correlated with cerebellar white matter and subregional cerebellar cortex volumes. ConclusionsTogether, these data expand our understanding of the phenotypic spectrum of 3q29del and identify executive function as a core feature linked to both psychiatric and neuroanatomical features of the syndrome.

Social affective and communication symptoms stand at the center of autism, and usually become apparent within the first 1-3 years of life. Symptom severity differs widely across toddlers and clinical outcomes, ranging from near-neurotypical to poor. The biological bases of this early and wide symptom diversity are largely unknown. While more than two dozen studies have attempted to subgroup early-age clinical heterogeneity, most studies fail to rigorously validate discovered subtypes using multiple methods, and none linked observed clinical subtypes with underlying functional neural signatures. Using a well-established approach for precision medicine patient subtyping (Similarity Network Fusion) and multiple rigorous validation methods, we integrated thoroughly replicated measures of social neurofunctional activation and social and language ability in 137 toddlers at early ages. Results identified three distinct social neural-clinical ASD subtypes, validated using multiple methods. One subtype was consistent with a profound autism profile with negligible social neural activation, severe social and language symptoms, low social interest, and little clinical improvement. Another ASD subtype had a contrasting pattern with only mildly reduced social neural activity, near neurotypical social and language abilities, and substantial age-related clinical improvement. One principal implication of these results is that the "spectrum" of ASD heterogeneity is not truly a continuous spectrum from the neurobiological and clinical perspective. The profound autism subtype is the neurofunctional, clinical and developmental opposite of the mild ASD subtype, suggesting different etiological mechanisms. A second implication is that neurobiological and clinical subtype differences highlight the need to develop subtype-specific treatments, particularly for the profound subtype. Third, treatment studies with an undetermined mix of subtypes could fail or succeed based on how many patients from each subtype are included in the mix.