Molecular Autism

A large subset of ASD associated genes, almost 50% of the highest confidence risk genes listed on the Simons Foundation Autism Research Institute database, are epigenetic modifiers. This suggests that the organization of sensory biology and its coupling to underlying genetic control are an important element underpinning this discord. Furthermore, sensory processing changes in individuals with autism spectrum disorder (ASD) has been a growing area of study in recent years. C. elegans have robust readouts for both developmental and sensory biology allowing these signatures of ASD to be systematically modelled. 52 epigenetic modifiers (65 strains) were selected for study in C. elegans based on gene function, presence of orthologues in C. elegans and the availability of viable putative null strains. This highlighted significant changes to reproduction, gross development and sensory processing across the range of epigenetic modifiers. Each strain was filtered against selective criteria for significant sensory and developmental phenotypes allowing for selective phenotypic profiles to emerge. These were three primary groups, those with sensory perturbations but unaffected gross development (6), developmentally affected genes with intact sensory function (10) and finally genes with impaired gross development and sensory function (11). Thus, this study provides a link between sensory and developmental outcomes in ASD associated mutant strains and suggests that more regular sensory testing should be performed in human cohorts to further refine sub-categorisation of ASD cohorts.

Mutations in the synaptic scaffold protein SHANK3 represent one of the most frequent genetic causes of autism spectrum disorder (ASD), yet the circuit mechanisms through which SHANK3 dysfunction leads to behavioral alterations remain incompletely understood. The anterior insular cortex (aINS) is a key integrative hub involved in socio-emotional processing, anxiety regulation, and social cognition, a group of behaviors frequently disrupted in ASD. Here, we investigated whether selective deletion of SHANK3 signaling in glutamatergic neurons of the aINS is sufficient to produce ASD-relevant behavioral and circuit phenotypes. Using conditional Shank3flox4-22 mice combined with stereotaxic viral delivery of Cre recombinase under the CaMKII promoter, we selectively deleted Shank3 in glutamatergic neurons of the aINS. Behavioral phenotyping revealed increased anxiety-like behavior, enhanced repetitive behavior, and impaired social memory, while sociability and locomotor activity were largely preserved. These behavioral alterations were accompanied by genotype-dependent differences in neuronal activity revealed by calcium imaging, indicating disrupted activity dynamics in insular glutamatergic neurons following Shank3 deletion. To assess the broader relevance of these findings, we evaluated the behavioral profile of BTBR T+ Itpr3tf/J mice, a model of idiopathic ASD, in the same battery of behavioral tests. Several behavioral alterations observed following insular Shank3 deletion partially overlapped with those present in BTBR mice, supporting the relevance of aINS Shank3 in ASD-related phenotypes. Together, these findings identify glutamatergic neurons of the aINS as a critical locus through which Shank3 dysfunction can disrupt socio-emotional, cognitive, and repetitive behaviors. Our results highlight the aINS as a key circuit node contributing to ASD-related behavioral alterations and provide mechanistic insight into how synaptic scaffold disruption leads to circuit dysfunction and produces behavioral alterations.

BackgroundPhelan McDermid syndrome (PMS), caused by SHANK3 haploinsufficiency, is a genetic form of autism spectrum disorder (ASD) that provides a genetically defined model for studying ASD-related circuit dysfunction. SHANK3 mutations disrupt synaptic organization and cortical synchrony, leading to attenuated gamma-band auditory steady-state responses (ASSRs). We investigated whether PMS-related electrophysiological signatures could be identified using machine learning and whether similar patterns are present in a subset of individuals with idiopathic ASD (iASD). MethodsEEG recorded during a 40-Hz ASSR paradigm was collected from 123 participants (42 TD aged 2-30, 56 iASD aged 3-31, 25 PMS aged 2-26). We extracted time-series, ERSP, FOOOF-derived spectral, and intertrial phase coherence (ITPC) features. XGBoost models with leave-one-out cross-validation classified PMS versus TD; the best age/sex-adjusted ITPC model was then applied to iASD participants to derive a Synchrony Atypicality Index (SAI). Unsupervised clustering of high-dimensional ITPC features was also performed. ResultsITPC-based models showed the strongest discrimination between TD and PMS participants (AUROC = 0.83). When applied to iASD participants, 35.7% exhibited elevated SAI, indicating a PMS-like gamma-band phase-locking profile. Classification of iASD versus PMS performed poorly in the full sample but improved markedly after excluding high-SAI iASD individuals, consistent with substantial heterogeneity within iASD. Unsupervised clustering of ITPC features identified PMS-enriched clusters that also captured high-SAI iASD participants. Results were consistent after controlling for age in sensitivity analyses. ConclusionsReduced 40-Hz ITPC is a mechanistically interpretable electrophysiological signature of PMS and identifies a biologically meaningful PMS-like subgroup within iASD, supporting biomarker-guided stratification.

AO_SCPLOWBSTRACTC_SCPLOWAltered social behaviors are prevalent in neurodevelopmental disorders like monogenic Rett syndrome, which is caused by pathogenic variants in the gene encoding the methylated DNA binding transcriptional regulator MeCP2. Monosynaptic projections from the ventral hippocampus to the medial prefrontal cortex (mPFC) modulate social memory, and are altered in male Mecp2 knockout (KO) mice. The standard tube test was used to define the social hierarchy between age- and genotype-matched triads over six consecutive days of round-robin competitions, and revealed that male Mecp2 KO mice form social ranks but display more submissive behaviors than those observed between similarly aged triads of male wild-type (WT) littermate controls. The same triads of each genotype performed similarly in the warm spot test, where mice of each genotype compete to stand on a single warm spot in a cage with a cooled floor. The dominant WT mouse from the prior tube test had preferential and active access to the beneficial place in the competition test (warm spot) showing more dominant behaviors than the other two WT mice. On the contrary, all three Mecp2 KO mice shared the warm spot equally, showing more submissive behaviors than those observed between the three WT mice. In vivo Ca2+ imaging from pyramidal neurons in the prelimbic mPFC during the warm spot test confirmed the presence of socially sensitive neurons, i.e., neurons that either increase or decrease their spiking activity during social interactions. mPFC pyramidal neurons in male Mecp2 KO mice showed fewer and smaller Ca2+ transients during baseline, as well as during each social interaction in the warm spot test, when their activity is less synchronous than in those of WT mice. In addition, chronically inhibiting the activity of mPFC-projecting excitatory neurons of the ventral hippocampus using an intersectional DREADD approach restored behavioral deficits in male Mecp2 KO mice. Together, these results demonstrate that male Mecp2 mice show a low behavioral engagement during social competition tests that alters their social hierarchy and is reflected in altered activity and synchrony between mPFC pyramidal neurons. Our observations also underscore the potential relevance of this long-range projection for altered social behaviors in other mouse models of neurodevelopmental disorders associated with autism.

Atypical sensory experiences are highly prevalent in autistic children and include both hyper- and hypo-responsivity, often accompanied by sensory overload. Alpha oscillations (7-13 Hz), which dynamically regulate cortical excitability, represent a plausible neural mechanism underlying these phenomena: reduced alpha activity is associated with enhanced sensory responsiveness, whereas increased alpha supports suppression of external input. Although decreased alpha power has been repeatedly reported in autism, it remains unclear whether this reduction reflects lower oscillatory amplitude or reduced temporal stability of alpha rhythms, two mechanisms with distinct neurophysiological implications. To better characterize alpha activity in autism, we examined resting-state alpha dynamics in non-autistic children (NA; n = 39), autistic children (AU; n = 52), and siblings of autistic children (SIB; n = 26), aged 8-14 years. We combined traditional broadband measures of relative alpha power, parametric separation of periodic and aperiodic activity, and single-event analyses that quantify the temporal structure of alpha oscillations. Both broadband relative alpha power and periodic alpha power were reduced in autism over parietal regions, replicating prior findings. Importantly, ordinal analyses revealed an intermediate profile in siblings, supporting a liability-related gradient of alpha alterations. However, single-event analyses demonstrated that the average amplitude of individual alpha bursts did not differ between groups. Instead, autistic children showed significantly shorter alpha burst duration and reduced alpha abundance (i.e., proportion of time occupied by rhythmic alpha episodes), with siblings again exhibiting intermediate values. Linear regression analyses confirmed that reductions in relative and periodic alpha power were primarily driven by decreased alpha abundance rather than diminished burst amplitude. These findings indicate that altered alpha activity in autism reflects reduced temporal stability and density of alpha events rather than weaker oscillatory amplitude per se. Reduced persistence of alpha rhythms may therefore represent a neural marker of altered cortical excitability and sensory regulation in autism. Lay summaryAutistic children often experience the world differently at the sensory level, including being more easily overwhelmed by sounds, lights, or other stimuli. In this study, we looked at a type of brain activity called alpha rhythms, which help regulate how strongly the brain responds to incoming information. We found that, in autistic children, these alpha rhythms were not weaker when they occurred, but they lasted for a shorter time and happened less often. Siblings of autistic children showed an intermediate pattern. These results suggest that sensory differences in autism may be linked to less stable brain rhythms that normally help control sensory input. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=158 SRC="FIGDIR/small/716324v1_ufig1.gif" ALT="Figure 1"> View larger version (32K): org.highwire.dtl.DTLVardef@1be733dorg.highwire.dtl.DTLVardef@7fea49org.highwire.dtl.DTLVardef@1ee9124org.highwire.dtl.DTLVardef@17af139_HPS_FORMAT_FIGEXP M_FIG C_FIG

The mechanistic role of the third visual pathway in autism spectrum disorder (ASD) remains unknown. We previously developed a neurofeedback therapy for autism targeting the posterior superior temporal sulcus (pSTS), a region in this network that underlies the perception and imagery of emotional facial expressions, resulting in improvements in adaptive behavior and recognition of fear in facial expressions. Here, we investigated the impact of this 5-session therapy on the functional connectivity of that core region of the third visual pathway. We found evidence for a profound reorganization of this network with treatment-induced decreases in connectivity between low-level visual areas, the pSTS, and the posterior occipital face area (OFA), and increased connectivity with higher-level visual regions (fusiform face area - FFA), right middle STS (mSTS), and parietal cortex. These changes, suggesting the restoration of connectivity in regions known to be underconnected in ASD, such as mSTS and pSTS, and in a set of regions belonging to the temporoparietal junction and the ventral attention network, which are known to be involved in broader aspects of social cognition, were positively associated with clinical improvements. The demonstration of treatment response associated with network reconfiguration paves the way for multicentric trials to probe this observed reorganization as a treatment target.

Autism spectrum disorder (ASD) is associated with deficits in synaptic plasticity across brain regions. While striatal dysfunction is observed in various mouse models of ASD, the effect of ASD-associated genes on striatal plasticity has not been well characterised. We previously showed that overexpression of the SFARI ASD risk gene eIF4E in transgenic (eIF4E-TG) mice produces ASD-like behaviours and impairs dorsal striatal dopamine release. Here, we examined whether eIF4E overexpression alters striatal synaptic transmission and plasticity. Using microscopy, whole-cell electrophysiology, optogenetics and fast-scan cyclic voltammetry, we assessed dendritic morphology and excitatory synaptic properties of spiny projection neurons (SPNs). The eIF4E-TG mice exhibited higher dendritic spine density, elevated AMPA and NMDA receptor-mediated mEPSC frequency, and reduced AMPA mEPSC amplitude. We also observed an increased induction rate and magnitude of long-term potentiation (LTP) in SPNs, which is NMDA receptor-dependent but is not prevented by pharmacological D1 or D2 receptor antagonism under the conditions tested. Finally, we found that somatic and dendritic Ca2+ signals evoked by brief depolarisation are altered in SPNs from eIF4E-TG mice. Together, these findings are consistent with eIF4E overexpression promoting an NMDA receptor-dependent form of striatal LTP that is not prevented by D1/D2 receptor antagonism.

Autism Spectrum Disorder (ASD) is a heterogenous condition that has no biologically relevant subtypes yet. Here, we utilized a multidimensional approach considering social deficits in ASD alongside negative valence and empathy dysfunction to distinguish ASD from Neurotypicals (NT) and to generate ASD subtypes using machine learning approaches. 114 subjects were analyzed, with 70 being NT and 44 ASD, all male with an IQ greater than 70, with 5 domains of personality (NEO-PI-r) and Reading the Mind the Eyes Test (RMET) scores included in the main classifier. We then used a multitude of behavioral (such as IQ, Broader Autism Phenotype, Autism Quotient, Interpersonal Reactivity Index) and clinical measures such as Autism Diagnostic Interview-Revised (ADI-R) alongside biological methods including DNA methylation of OXTR gene and resting-state functional connectivity (rsFC) to validate the putative subtypes. 30 ASD who received IN-OXT in a randomized, placebo-controlled, within-subject design and 17 new NT were part of the rs-FC analysis. A random forest tree algorithm was used to classify NT and ASD and Shapley Additive Explanation Values were used to describe the model and to cluster ASD subtypes using K-Means clustering. Three subtypes were generated with two of them being highly distinctive in behavioral and brain functional traits. One subtype named NASA (or Negative Affect and Social Aloofness) was characterized by high Neuroticism and Low warmth alongside lower rsFC between networks involved in social cognition, self-awareness, and sensory processing, such as Superior Temporal Sulcus and Sensorimotor Network; or ACC/Insula with visual cortex, Posterior Cingulate Cortex and visual cortex. The second subtype NADR (Neurocognitive and Affect Dysregulation with Resistance to Change) was characterized by higher DNA methylation of OXTR, hyperconnectivity between default mode network, reward areas and inferior frontal and fusiform networks. NADR has more cognitive difficulties and higher ADI-R scores as well as higher Neuroticism, higher personal distress, higher rigidity and lower openness. In a mixed model analysis, we found that IN-OXT in a dose dependent manner impacted NASA subtype by modulating rsFC between PCC and cerebellum and between Brainstem/Cerebellum and Parietal cortex to probably enhance social cognition and to reduce negative valence in this subtype.

Previously we found that female autistic youth (Aut-F) showed reduced brain response in dorsal striatum (putamen) when viewing human motion, alongside larger rare copy number variants that included genes expressed in early striatal development. Thus, striatal differences may characterize Aut-F, but broader systems-level and behavioral implications of these differences remain unexplored. We conducted secondary data analysis of the sex-balanced cohort (8-17y) in which we first discovered these patterns, in order to: 1) understand how functional connectivity between putamen and frontal targets might vary from the non-autistic population, and differ by sex; and 2) explore which brain connectivity and phenotypic features best predicted executive function. Using psychophysiological interaction analysis (N=184), we found that Aut-F youth (n=45) showed reduced functional connectivity between left anterior putamen (Pa) and dorsal premotor cortex/pre-supplementary motor area versus matched non-autistic female peers (NAut-F; n=45), suggesting reduced engagement of a typical Pa-frontal pathway for attentional regulation. Best subsets regression (N=200) indicated that left Pa-left dorsolateral prefrontal functional connectivity explained significant variance in executive functioning across all participants, controlling for neurotype. These results suggest that striatal differences in Aut-F may have adaptive consequences in part due to impacts on connectivity between Pa and frontal regions important for attentional control. Lay summaryWe previously found that female autistic people show differences in a part of the brain called the striatum. Some parts of the striatum connect to the frontal lobe of the brain, and may help people control their attention and behavior. We studied how the striatum "talked to" the frontal lobe in autistic girls. We found out that this communication is lower in autistic than non-autistic girls. We also found out that how much striatum "talks to" frontal lobe helps explain differences in how well both autistic and non-autistic youth of both sexes control their attention and behavior.

A growing number of studies point to a key role of the amygdala in Autism Spectrum Disorders (ASD). The amygdala is involved in several processes in ASD including emotional valence, facial recognition, regulation of social learning, empathy, and anxiety. Brain imaging and postmortem studies demonstrate altered amygdala development in children with ASD, associated with impairment in social behavior and anxiety. There is limited information regarding the molecular pathology of the amygdala in children with ASD. We conducted RNAseq profiling on postmortem amygdala samples from male children (4-14 yrs old) with ASD (n=8) and normotypic male children (n=6). Furthermore, we conducted drug repurposing analysis to identify compounds predicted to reverse the transcriptomic signatures identified in order to identify potential therapeutic targets for development of early intervention treatments. Full transcriptome gene expression profiling implicated molecular pathways involved in neuroimmune signaling, glycogen and carbohydrate metabolism, matrix metalloproteases, neurodevelopment, estrogen receptor signaling, and synaptic signaling. Targeted pathway analysis of the top 10% of differentially expressed genes implicated pathways involved in extracellular matrix organization, immune signaling, and synaptic signaling. Our drug repurposing analysis identified sleep modifying compounds and anti-inflammatory compounds including COX2 and GSK3 inhibitors amongst the top predicted therapeutic compound classifications. PDGF receptor tyrosine kinase inhibitors were identified as a top potential therapeutic mechanism of action. Our results point to alterations in immune signaling, extracellular matrix organization, and synaptic signaling in the amygdala of children with ASD. Furthermore, our results identified a number of potential therapeutic drug targets for development of early intervention strategies.

Visual processing undergoes rapid refinement in the first year of life, supporting the emergence of higher-order cognitive, language, and motor functions. Visual evoked potentials (VEPs) provide a non-invasive measure of visual system maturation that may shed light on heterogeneous developmental trajectories among infants at high familial likelihood for autism. Infants with an older sibling with autism spectrum disorder (N = 177 at 6 months; N = 132 at 12 months) participated in the Infant Brain Imaging Study-Early Prediction (IBIS-EP) study. Pattern-reversal VEPs were recorded at 6 and 12 months, and developmental skills were assessed at 24 months using the Bayley Scales of Infant and Toddler Development (Bayley-III). VEP components were characterized by P1 amplitude, latency, and trial-to-trial variability in latency. Associations with 24-month cognitive, language, and motor scores were examined using general linear models controlling for age, site, sex, and trial count. Robust VEPs were observed at both timepoints, showing age-appropriate morphology and expected developmental changes, including decreases in P1 latency and amplitude from 6 to 12 months. Greater trial-to-trial variability in P1 latency at both timepoints was significantly associated with higher cognitive and language scores at 24 months. Variability in visual cortical response timing was the strongest neural correlate of developmental skills in infancy. These findings suggest that temporal variability in early neural responses may reflect adaptive sensory circuit flexibility rather than inefficiency, potentially facilitating experience-dependent tuning of visual pathways. VEPs offer a mechanistic window into how developing sensory systems scaffold individual differences in early developmental trajectories. Research HighlightsO_LITrial-to-trial variability in visual cortical response timing predicts cognitive and language outcomes at 24 months in infants at familial likelihood for autism. C_LIO_LIMean P1 latency did not predict outcomes, suggesting variability is a more sensitive early neural marker than average response timing. C_LIO_LIGreater neural response variability in infancy may reflect adaptive sensory circuit flexibility rather than noise or inefficient processing. C_LIO_LIVEP-based biomarkers provide a scalable mechanistic window into how early sensory processing scaffolds cognitive and language development. C_LI

The brain generates predictions to prepare for upcoming events. Because the environment is not perfectly predictable, the brain also estimates the certainty of these predictions and adjusts preparatory processes accordingly. Given that autistic individuals often resist even small changes to everyday routines, we hypothesized altered tuning of prediction certainty in autism. To test this, EEG was recorded from adolescents and young autistic adults (n = 20) and from age- and IQ-matched non-autistic adults (n = 19) during a probabilistic cued target identification task during which cue validity was systematically varied across four levels: 100%, 84%, 67%, and 33%. Participants were not informed of the cue-target validity nor when it changed. We focused on two neural signatures of anticipatory readiness, contingent negative variation (CNV) and alpha-band event-related desynchronization (-ERD), and one of cognitive updating: the P3 to targets and to invalid (e.g., a non-target in place of the target) stimuli. Across groups, preparatory activity increased as contextual certainty decreased, with larger CNV amplitudes and stronger -ERD preceding targets in lower-probability contexts, suggesting enhanced preparatory engagement under greater uncertainty. Furthermore, larger CNV amplitudes predicted faster reaction times, indicating functionally significant anticipatory dynamics. However, modulation of both neural preparation and response times as a function of cue-target probability was significantly reduced in the autistic group. In addition, autistic participants showed diminished probability-dependent modulation of the P3b to both targets and invalid stimuli, and coupling between anticipatory activity (CNV) and subsequent updating (P3b) was observed in non-autistic participants whereas it was absent in autism. Together, these findings suggest that while predictive mechanisms are present in autism, anticipatory processes are less flexibly tuned to contextual uncertainty and less effectively linked to subsequent cognitive updating. This reduced adaptability may reflect difficulty adjusting internal predictive models to changing environmental contingencies, potentially contributing to core features of autism such as resistance to change and insistence on sameness. HighlightsO_LIAnticipatory brain mechanisms (CNV and alpha desynchronization) are present in autism and are behaviorally relevant, predicting faster responses. C_LIO_LIAutistic individuals exhibit reduced modulation of anticipatory CNV and alpha activity as a function of cue-target validity. C_LIO_LIP3b responses to both targets and invalid stimuli show diminished sensitivity to contextual probability in autism, consistent with altered prior updating. C_LIO_LIThe link between anticipatory activity and cognitive updating (i.e., CNV to P3b) is disrupted in autism. C_LIO_LIP3a amplitude to invalid stimuli is reduced in autism, suggesting diminished engagement of violation-sensitive processes. C_LIO_LITogether, findings point to less flexible tuning of predictive mechanisms and reduced adaptation to contextual uncertainty in autism. C_LI

PurposeNavigational ability develops throughout childhood alongside the maturation of brain regions supporting egocentric and allocentric processing. In Autism Spectrum Disorder (ASD), atypical hippocampal development may impact flexible spatial memory; however, findings on navigational ability in autistic children remain inconsistent. This study aimed to compare both objective and perceived navigation ability in children with ASD and typically developing (TD) peers. MethodTwenty-six children with high-functioning ASD and twenty-five age- and gender-matched TD children (M_age = 12.04 years, SD = 1.64) completed a battery of navigational tasks from the Spatial Performance Assessment for Cognitive Evaluation (SPACE), including Path Integration, Egocentric Pointing, Mapping, Associative Memory, and Perspective Taking. Perceived navigation ability was assessed using the Santa Barbara Sense of Direction (SBSOD) scale. ResultsNo significant group differences were observed across any objective navigation tasks. However, children with ASD reported significantly lower perceived navigation ability compared to TD peers. ConclusionThese findings suggest a dissociation between perceived and actual navigational ability in ASD. By early adolescence, objective navigation performance appears intact, potentially reflecting sufficient maturation of underlying neural systems or the presence of compensatory mechanisms. The results underscore the importance of incorporating objective, task-based measures when assessing cognitive abilities in autistic populations.

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterized by a broad spectrum of behavioral impairments. While multiple genetic and environmental factors are attributed to its cause, biological underpinnings are still poorly understood. We investigated an ASD-associated gene, WAC, for its neurobehavioral aspects using C. elegans and mice. Studies of C. elegans with wac gene deletions (wac-1.1 and wac-1.2) showed enhanced acetylcholine-associated behavior, as indicated by the aldicarb assay. No alteration in acetylcholine levels or acetylcholinesterase activity was observed. Upon further investigation, we found that the elevated cholinergic transmission resulted from increased activity of nicotinic acetylcholine receptors (nAChRs). Additionally, we observed reduced motility and dopamine-associated behaviors, along with a reduced ability to switch from crawling to swimming, a serotonin-dependent behavior. Upregulation in mRNA expression of the lev-1 gene was observed. Conversely, a feedback-counterbalancing response in the form of downregulated genes, acr-2, unc-17, unc-63, and unc-50, was also observed. Surprisingly, lev-1 RNAi did not reverse the enhanced cholinergic transmission in PHX2587 worms, indicating the involvement of other players. To validate our findings, we also assessed CHRNA7 levels in Wac+/- mice. While some genetic compensation was observed in heterozygous mice, we found a direct, inverse correlation between Wac mRNA expression and CHRNA7 levels in the mouse brain cortex, corroborating our findings from C. elegans. Overall, these studies indicate that wac gene deletion in C. elegans exhibits a neurotransmitter alteration that is relatable to ASD. Graphical Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=61 SRC="FIGDIR/small/709202v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@1771dc4org.highwire.dtl.DTLVardef@1434b4eorg.highwire.dtl.DTLVardef@10525ecorg.highwire.dtl.DTLVardef@fcd8a9_HPS_FORMAT_FIGEXP M_FIG C_FIG

BackgroundAutistic individuals experience higher rates of sleep problems throughout their lives, and there is considerable heterogeneity in manifestations of these issues that remains unexplained. Here, we examine associations over time of heterogenous sleep trajectories with autism diagnosis, and behavioural and genetic factors related to autism. MethodWe used data from the Avon Longitudinal Study of Parents and Children (N=13,886, autistic n=150). The primary outcome was parent and self-reported night-time sleep duration, measured on 10 occasions (between 0.5y and 15.5y). The independent variables were autism diagnosis, autism polygenic score (PGS) and four parent-reported autistic traits: repetitive behaviour, social communication, speech coherence, and sociability. Latent class growth analysis was conducted to identify heterogenous classes of sleep trajectories, and these trajectory classes were regressed onto the independent variables. ResultsFour night-time sleep duration trajectory subclasses were identified; shorter (n=512, 4.1%), longer (n=1654, 13.1%), intermediate-shorter (n=3630, 28.8%), and intermediate-longer (used as the reference class; n=6825, 54.1%). An autism diagnosis was associated with a shorter or intermediate-shorter sleep duration trajectory, compared to the reference class. Similarly, higher scores in domains of repetitive behaviour, speech coherence and social communication were associated with shorter sleep duration trajectories. The autism PGS and sociability were not associated with any sleep trajectories compared to the intermediate-longer sleep trajectory (reference group). ConclusionAn autism diagnosis and specific autistic traits were associated with poorer long-term sleep outcomes across childhood and adolescence, highlighting the need for early, sustained sleep interventions, and the potential of trait-specific mechanisms for sleep problems. HighlightsO_LIFour distinct night-time sleep duration trajectories were identified across development C_LIO_LIAutism diagnosis predicted shorter and intermediate-shorter sleep trajectories C_LIO_LISpecific (but not all) autistic traits were linked to shorter sleep trajectories C_LIO_LIAutism PGS did not predict sleep duration trajectories C_LI

WAC is an autism-associated gene involved in neurodevelopment. However, the effects of reduced WAC function on behavior and synaptic regulation in vivo remain unclear. Taking cues from the previous studies on the wac gene and the C. elegans model of ASD, we elucidated the effects of wac gene deletion on food-leaving behavior, a known parameter linked to ASD associated genes along with the cholinergic pathway. wac-deficient worms exhibited curtailed food-leaving behavior. Notably, observed phenotype was similar to that exhibited by nematodes with mutation in ASD related gene, neuroligin. In addition, wac-deficient worms showed impaired growth, reduced pharyngeal pumping, and lifespan. To examine potential synaptic mechanisms, we analyzed expression of genes related to cholinergic signaling across all developmental stages (L1-L4) through young adult (YA). Stage-specific transcriptional changes were observed, with increased expression of ace-1 and acr-3 at L1, acr-3 at L3, and acr-3, cha-1, lev-1, and lev-10 at L4. The transcriptomic alteration was most prominent at YA stage, exhibiting upregulation of ace-1, cha-1, cho-1, lev-1, lev-10, unc-17, unc-29, unc-38, and unc-50. To identify specific suppressor of upmodulated Ach signaling, RNAi of the upregulated genes was performed. cho-1 was identified as a specific suppressor of elevated Ach signaling. cho-1 encodes a high-affinity choline transporter responsible for choline uptake in the pre-synapse. These studies identify the molecular mechanisms pertaining to up-modulation of cholinergic signaling in wac mutant worms. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=112 SRC="FIGDIR/small/719318v1_ufig1.gif" ALT="Figure 1"> View larger version (24K): org.highwire.dtl.DTLVardef@1bdf8a9org.highwire.dtl.DTLVardef@1104825org.highwire.dtl.DTLVardef@1f09682org.highwire.dtl.DTLVardef@293b08_HPS_FORMAT_FIGEXP M_FIG C_FIG

BackgroundNaturalistic fMRI provides an ecologically valid window into social brain function, yet binary diagnostic labels may obscure neural signatures linked to the continuous spectrum of social deficits. We investigated whether social brain alterations in autism spectrum disorder (ASD) follow a categorical, dimensional, or "dual-track" architecture. MethodsWe analyzed fMRI data from 428 youth (262 ASD, 166 typically developing; ages 5-22) watching two films: The Present and Despicable Me. Using Principal Component Analysis (PCA) to quantify primary (PC1) and secondary (PC2) synchronization, we employed variance partitioning to disentangle the contributions of categorical diagnosis from continuous symptom severity (Social Responsiveness Scale-2, SRS-2). ResultsDuring The Present, reduced synchronization was widespread. In social-motivational hubs (medial prefrontal cortex, caudate), reductions were largely explained by variance shared between diagnosis and SRS-2 scores. In contrast, the left amygdala exhibited a unique dimensional association with SRS-2 scores independent of categorical diagnosis. Secondary response patterns (PC2), reflecting complex temporal integration, revealed further unique dimensional effects in the cuneus. Notably, these signatures were stimulus-dependent, manifesting during the emotionally complex narrative of The Present but not during the slapstick-oriented Despicable Me. ConclusionsWhile core social-motivational hubs reflect overlapping diagnostic and dimensional deficits, the amygdala and secondary visual patterns provide distinct, dimension-specific signatures of social impairment. This variance partitioning approach supports a Research Domain Criteria (RDoC) framework, highlighting the necessity of integrating dimensional assessments and narrative complexity to characterize the neural architecture of autism.

BackgroundStructural white matter (WM) alterations are recognized in Autism Spectrum Disorder (ASD), yet the functional connectivity (FC) of WM networks and its clinical significance remain largely under-explored. MethodsThis study aimed to investigate aberrant FC patterns within intra-WM (WM-WM) and WM-gray matter (WM-GM) networks in a large ASD cohort. Resting-state fMRI data from 272 ASD individuals and 368 typical controls (TC) from the ABIDE-II dataset were analyzed. We constructed WM-WM and WM-GM FC networks using Pearson correlations between atlas-defined regions, applied ComBat harmonization, and employed Network-Based Statistics (NBS) to identify group differences. Associations with clinical symptoms were assessed using Social Responsiveness Scale (SRS) scores, and a CatBoost algorithm was used for diagnostic classification based on connectivity features. ResultsNBS analyses revealed significantly increased connectivity in ASD for 116 WM-WM pairs and 58 WM-GM pairs (P<0.05, FWER-corrected). Critically, the strength of these aberrant WM-WM functional connections exhibited a significant negative correlation with SRS total scores (r = -0.22, P < 0.001), whereas WM-GM connectivity showed no such significant association. The hybrid CatBoost classifier, integrating both WM-WM and WM-GM features, achieved moderate diagnostic discrimination (AUC = 0.669 {+/-} 0.040). ConclusionThese results offer novel insights into the aberrant functional architecture of WM-related networks in ASD, particularly linking intra-WM dysconnectivity to symptom severity, thereby enhancing our understanding of the neural substrates underlying social-communicative deficits.

Despite autism's prominent genetic etiology and early-life origins, parsing genetic effects contributing to the condition into those that operate directly (via allelic transmission to offspring) vs. indirectly (via influencing prenatal environment) remains challenging. We examined this using a novel design leveraging 3-generation family linkage in Danish national registers. The cohort included all children born in Denmark from 1998-2015 and their relatives identified through 3-generation family linkage. The analytic sample comprised full maternal cousin pairs, including parallel (children of mother's sister) and cross cousins (children of mother's brother). Exposures were diagnoses in the index mother previously associated with offspring autism; the outcome was autism diagnosis in cousins of the index child. We used Cox proportional hazards models to estimate associations separately in parallel and cross cousins, followed by comparisons of these hazard ratios to infer mechanisms. Several maternal diagnoses (e.g., postpartum hemorrhage, personality disorders, epilepsy) were associated with autism in both parallel and cross cousins, consistent with shared direct genetic effects. Other conditions (e.g., false labor, recurrent major depressive disorder, other anxiety disorders, systemic connective tissue involvement) showed stronger associations in parallel than cross cousins, supporting additional indirect genetic effects operating through the prenatal environment. Adjustment for the same diagnosis in the cousin's own mother did not substantially change estimates, providing no evidence for an additional role of non-genetic mechanisms associated with the diagnosis. These findings suggest that both direct and indirect genetic effects contribute to observed links between maternal health and offspring autism, highlighting etiologic heterogeneity and highlighting a registry-based family design to separate these pathways without genetic data.

Atypical social functioning is a core feature of autism, yet findings remain fragmented across components and development. We aimed to systematically integrate this literature and characterize the organization, development, and moderators of social functioning in autism. We conducted a systematic review and meta-analysis of behavioral studies published between January 1990 and August 2025, identified through PubMed, Web of Science, and prior reviews, including studies with clinically diagnosed autistic individuals and neurotypical controls. A qualitative synthesis and two complementary quantitative meta-analyses were performed, with risk of bias evaluated through study-level characteristics. A total of 2,622 studies (94,114 autistic and 172,847 neurotypical individuals across 32 countries) were included, covering 22 social components that clustered into five domains. Overall group differences were substantial (Hedges g = -0.744, 95% CI [-0.797, -0.690]). Differences emerged earliest in motivation-based processes ([~]6 months), followed by motor, emotion, and inference domains, and showed age-related divergence alongside improvement in some skills. Cross-domain analyses revealed stronger interdependencies in autism and an organizational pattern most consistent with serial relationships among domains. These findings should be interpreted in light of methodological heterogeneity, underpowered samples, and uneven cultural representation. Together, the results provide an integrative framework for understanding the organization and development of social functioning in autism, with implications for precision subtyping, developmentally timed interventions, and neurodiversity-informed research and policy. This study was pre-registered (PROSPERO: CRD42024566141).