Journal of Autism and Developmental Disorders

Abstract Autistic young adults experience substantial gaps in services supporting community living and participation. The Community Autism Peer Support (CAPS) program is a community-based intervention in which trained autistic peer specialists provide individualized support to autistic young adults pursuing self-determined goals related to community participation and independent living. We conducted a single-site, two-arm randomized controlled trial to evaluate the feasibility of implementing the CAPS program. Forty autistic adults aged 18 to 30 years were randomized to CAPS (n = 20) or services as usual alone (n = 20) and assessed at baseline, 3 months, and 12 months. Study findings showed that CAPS attracted autistic young adults with diverse demographic and diagnostic backgrounds, and most intervention participants remained engaged in services for extended periods. While the study was underpowered to detect statistical differences in outcomes because it was not a main focus of the research, a consistent pattern of results favored the CAPS condition across all outcomes. The largest positive signals were observed for overall and social quality of life, with additional favorable changes in internalized stigma, unmet needs, social functioning, loneliness, and positive autistic identity. Findings provide support for the feasibility and promise of an autistic-delivered peer specialist model focused on community living and participation. The consistent pattern of favorable changes supports continued development of CAPS as a person-centered approach to addressing outcomes important to autistic adults.

In many high-income countries, autistic children attend preschools ranging from exclusive special education (SE) to inclusive mainstream education (ME). These settings differ in staff expertise, capacity to implement structured autism interventions, exposure to typically developing peers, and cost. In this prospective longitudinal study, we compared 119 autistic children across three preschool settings in southern Israel: SE with TABAM services, an extended intervention program; SE without TABAM; and ME. Children completed behavioral assessments at the beginning and end of their first preschool year, yielding measures of cognition, autism symptom severity, joint attention, verbal abilities, adaptive behaviors, and aberrant behaviors. Developmental trajectories varied across children, with some demonstrating marked gains and others showing limited progress. On average, developmental changes were modest across most domains and were not explained by educational setting. The only exception was verbal ability, where children in SE with TABAM showed greater gains than children in SE without TABAM. These findings suggest that autistic children in ME and SE demonstrated broadly similar developmental trajectories during their first preschool year. Further large-scale research is needed to identify which children may benefit more from specific educational environments and intervention approaches, and to inform ongoing efforts to optimize preschool services for autistic children.

The Autism Spectrum Quotient (AQ-50) is widely used to assess autistic traits, yet its Hungarian version has not been psychometrically evaluated. We assessed the reliability, factor structure, temporal stability, convergent validity, and clinical utility of the Hungarian AQ-50 and a revised translation (AQ-50-HU-R) in two samples (N1 = 1967; N2 = 423), including autistic and non-autistic participants. The AQ-50-HU-R showed high internal consistency and test-retest reliability. A bifactor model provided the best fit ({chi}2[1125] = 1650.433, p < 0.001; CFI = 0.991; TLI = 0.990; RMSEA = 0.033 [90% CI = 0.030-0.037]; SRMR = 0.083), with 71% of common variance attributable to a general autistic traits factor. The total score distinguished clinically verified autistic participants from participants reporting no ASD diagnosis (AUC = 0.906), with a cutoff of 25. Associations with ADOS scores were weak or nonsignificant. The AQ-50-HU-R is best interpreted as a reliable total-score screening measure, supporting referral for comprehensive autism assessment.

Autistic adults face considerable challenges in receiving adequate support, from both paid/formal (such as from disability services) and unpaid/informal (for example, from friends and family) sources. Having adequate support can lead to better health and well-being outcomes. However, most instruments designed to assess adequacy of support were not made specifically for/with autistic adults. This paper presents a psychometric validation of the AASPIRE Adequacy of Supports and Information Scale (AASIS), a community-informed adaptation of a previously developed instrument (the Quality of Care and Support scale; Lucas-Carrasco et al., 2011), designed to be relevant and accessible to autistic adults. We also used the AASIS to explore correlates of perceptions of support in a sample of 798 autistic adults. Our confirmatory factor analysis supported a two factor structure for the AASIS (factor one: Supports; factor two: Information). Further testing confirmed the instrument was invariant across several groups, including race/ethnicity, gender, intellectual disability, communication fluency, and self versus proxy-report. Regression analyses suggested that the way in which participants joined the study (i.e., through community advertisements or via established healthcare/disability services) impacted whether they viewed their support as adequate. Additionally, a higher number of adverse childhood events and greater experience of discrimination were related to worse perceptions of support adequacy across both factors. Our findings support the preliminary validity of the AASIS across a variety of autistic people, though further testing is warranted. Findings also point to the importance of addressing the needs of autistic people who are minoritized and/or who have complex trauma histories.

Purpose: In clinical trials, treatment efficacy is commonly assessed by comparing control and treatment groups. However, in large samples, even small and clinically trivial differences may achieve statistical significance. Accordingly, the Minimal Clinically Important Difference (MCID) is used as a threshold to determine whether statistically-significant effects are also clinically meaningful to patients. The objective of this study was to estimate the MCID for the Childhood Autism Rating Scale Second-Edition (CARS2) using the Patient Impression of Change (PIC) as an external anchor. Methods: Single-item PICs are not well suited to characterizing improvement in a multifaceted disorder such as ASD. Accordingly, the 77-item Autism Treatment Evaluation Checklist (ATEC) was used as a multi-item PIC. CARS2 and ATEC were administered concurrently to 62 children with ASD, aged 1.8-7.9 years, with assessments conducted six months apart. Results: The correlation between changes in CARS2 and ATEC total scores was 0.41-0.44 (p<0.0001), supporting the use of ATEC as an anchor measure. Two anchor-based methods yielded MCIDs of 2.39-2.82 CARS2 points. Two distribution-based methods produced MCIDs of 1.33-3.32. Conclusions: Taken together, these approaches suggest that a between-group difference of 2.6 CARS2 points (the midpoint of the anchor-based estimates) may serve as the MCID in children with ASD.

Purpose: This study examined whether word-based and non-word natural language sampling (NLS) measures complement standardized language scores in characterizing expressive communication among preschool children with autism with language impairment (AUT-LI), Down syndrome (DS), and fragile X syndrome (FXS). Method: Participants included 82 preschool children with AUT-LI (n = 32), DS (n = 34), or FXS (n = 16). Expressive communication was characterized using the Preschool Language Scales and 10-minute natural language samples collected during a standardized play-based protocol. NLS measures included traditional word-based metrics, such as lexical diversity, intelligibility, and word approximations, as well as tiered non-word vocalization measures, including non-speech, single-phoneme, and multi-phoneme vocalizations. Analyses examined age associations, diagnostic group differences, between group differences in variability, and exploratory communication profiles derived using principal component analysis and partitioning around medoids clustering. Results: Diagnostic groups did not significantly differ on standardized expressive language scores. Children with FXS showed higher performance than the AUT-LI and DS groups on several word-based NLS measures, whereas non-word vocalization measures primarily revealed differences in within-group variability. Word-based NLS measures were consistently associated with standardized expressive language skills, while associations for non-word vocalizations varied by vocalizations type. Cluster-validity indices factored a two-cluster solution. A hypothesis-informed three cluster solution that included non-word vocalizations suggested Higher Language, Lower Output, and High Output-Low Structure profiles. Conclusions: Standardized and NLS measures provide complementary descriptions of expressive communication in children with neurodevelopmental disorders. Non-word vocalization coding may be especially useful for describing clinical meaningful variation among children with limited expressive language. Keywords: Natural language sampling; expressive language; neurodevelopmental disorders; autism spectrum disorder; Down syndrome; Fragile X syndrome

Catatonia in autistic individuals may resemble worsening autism yet represent a potentially treatable departure from baseline functioning. We compared item-level catatonic signs in autistic and non-autistic patients and evaluated treatment-associated change during electroconvulsive therapy (ECT). This single-center observational cohort included patients with catatonia who received ECT from May 2022 through April 2026. The 23-item Bush-Francis Catatonia Rating Scale (BFCRS) was assessed longitudinally. Pretreatment BFCRS data were available for 104 patients, including 41 autistic and 63 non-autistic patients, with 993 near-complete repeated assessments available. Pretreatment item presence was modeled using a three-level clinical-group variable with adjustment for age, biologic sex, and calendar year. Compared with non-autistic patients, patients with autism and intellectual disability had higher adjusted odds of eight activated, repetitive, or behaviorally dysregulated signs and lower odds of immobility/stupor. Among 96 patients with paired first and last eligible BFCRS assessments, multiple items improved in both cohorts. Generalized estimating equations demonstrated longitudinal declines in total BFCRS scores and multiple psychomotor-domain scores, with no clinical-group-by-time interaction surviving false-discovery rate correction in unrestricted or 30-, 60-, 90-, and 180-day models. Autism-specific Kanner analyses identified seven significant fixed-endpoint severity-item improvements after false-discovery rate correction, six of which were reproduced longitudinally. Catatonia in autism with intellectual disability was characterized by a phenotype that may resemble worsening autism during later regression, and many constituent signs demonstrated treatment-associated improvement during ECT.

Generalization is a key cognitive process that allows humans to flexibly apply prior knowledge to guide new behaviors. Difficulties with generalization and flexibility are observed across neurodevelopmental disorders, especially autism, limiting adaptive function and quality of life. Cognitive-behavioral treatment benefits some but not all autistic individuals. As treatment requires application of learned skills to everyday life, variability in generalization ability may limit intervention success in autism. While cognitive substrates of learning and generalization are well established, their potential for explaining clinical outcomes is not known. Here, we combined a category learning task with computational modelling to distinguish two learning strategies underlying generalization -- prototype abstraction vs. exemplar memorization -- and tested whether individual differences in these learning strategies predicted real-world intervention outcomes in autistic youth. Fifty-four participants completed the category learning task at two pre-intervention timepoints, and then completed Unstuck and On Target:14-22 intervention targeting flexible problem solving, goal setting, and planning. We found that participants who consistently relied on prototype abstraction (N=26) were subsequently more likely to benefit from the intervention, showing improvement in parent- and self-reported flexibility. These findings identify prototype abstraction as a clinically relevant cognitive capacity that may help explain individual differences in intervention response and support the tailoring of interventions. More broadly, they demonstrate the value of linking basic cognitive mechanisms to clinical outcomes and may inform strategies to enhance the effectiveness of cognitive-behavioral interventions for youth with developmental disabilities.

Purpose Autistic adults have diverse communication characteristics that are not well captured by standard demographic measures. Communication affects self-determination, relationships, access to healthcare, and services. Characterizing communication differences may improve research and intervention targeting for meaningful subgroups of autistic adults. Methods The Academic Autism Spectrum Partnership in Research and Education (AASPIRE) Outcomes Project team used a community based participatory research (CBPR) approach to develop a self- or caregiver-report module to characterize communication among autistic adults. The 10-item module asks about receptive and expressive communication, literacy, speech reliability, usage of digital communication, use of alternatives to speech, and communication fluency. It can be completed directly, with or without support, or via a caregiver. We used baseline survey data from 844 autistic adults to evaluate the module and derived a five-level variable, Communication Profile, from selected module items to stratify participants. We examined completion feasibility, response consistency, and construct validity. We also assessed test-retest reliability in a 15% random subsample who completed a 2-week retest following the 6-month survey, with oversampling of caregiver-report respondents. Results The Communication Characteristics module demonstrated high completion feasibility, minimal systematic error, and strong construct validity. The Communication Profile variable stratified participants into five meaningful communication profiles and demonstrated strong construct validity and substantial test-retest reliability ({kappa} = .69). Conclusion The Communication Characteristics module and Communication Profile variable provide a valid approach for characterizing communication diversity among autistic adults for research, clinical, and service settings. The full AASPIRE Measurement Toolkit is available at https://aaspire.org/measurement. Lay Summary Autistic people communicate in many different ways, and their communication may change in different situations. We developed and tested a set of survey questions to describe an individuals communication. We also used the results to describe 5 groups of autistic people based on how they communicate, without treating these groups as different types of autism.

Objective: Mental health challenges are highly prevalent in autism, but the degree to which they are similar in experience and etiology to the general population remains unclear. This study's objective was characterization of phenotypic and genetic architectures of psychiatric symptomatology in versus out-of-autism. Methods: Psychiatric symptoms were evaluated using the Child Behavior Checklist (CBCL) in 22,152 children (8-15 years): 11,111 autistic children with verbal abilities from SPARK and 11,041 non-autistic children from ABCD. The CBCL's canonical, population-wide factor structure and genetic associations were compared between cohorts. In parallel, exploratory factor analysis was conducted in SPARK, with resulting dimensions associated with key clinical phenotypes (cognitive ability, co-occurring neuropsychiatric diagnoses), polygenic scores (PGS) for psychiatric disorders, and de novo burden in autism-associated genes. Results: Confirmatory factor analysis supported the canonical structure in ABCD but not in SPARK. Psychiatric PGS associations with canonical CBCL subscales were weaker in SPARK than in ABCD, with the ADHD PGS association to Attention problems lower in SPARK ({beta}=0.05 [CI: 0.04,0.06] than in ABCD ({beta}=0.17 [0.13,0.21]). SPARK exploratory factor analysis replicated canonical internalizing factors while revealing other structural departures, including a distinct Developmental Delays factor and dispersion of social problems across multiple factors. The Developmental Delays factor had the strongest associations with de novo burden and lower cognitive ability but was weakly associated with psychiatric PGS. In contrast, common genetic variation explained larger proportions of variances in somatic and inattentive factors and had stronger PGS associations. Conclusions: Correlation structures and genetic architectures of psychiatric symptoms differed in autism compared to the broader population, emphasizing the need for autism-specific approaches in assessment and treatment.

Background: Autistic Chronic Energy Depletion Syndrome, commonly referred to as Autistic Burnout, is a debilitating condition characterized by exhaustion, loss of function, and reduced tolerance to stimuli. While several instruments attempt to measure it, validation studies have only used cross-sectional designs and/or convenience samples with low support needs, limiting understanding of their performance across heterogeneous, autistic populations and over time. Methods: Using a community-based participatory research (CBPR) approach, we revised the 27-item AASPIRE Autistic Burnout Measure (AABM) into a 14-item AASPIRE Autistic Burnout Measure-Revised (AABM-R) and tested it in a longitudinal study of 835 autistic adults recruited from healthcare systems, disability services, and the community. Participants completed surveys directly (with or without support) or via a caregiver. We assessed structural validity and measurement invariance using exploratory and confirmatory factor analysis, tested construct validity through a priori hypothesis testing, examined discriminant validity from depression using longitudinal factor analysis and cross-lagged panel models, and assessed criterion validity using ROC analysis. Results: The AABM-R demonstrated a clear single-factor structure among direct reporters, with and without support, and measurement invariance across these groups; findings were less conclusive for the smaller caregiver-report subsample. Autistic burnout correlated as hypothesized with stressors (e.g., discrimination, masking, adverse childhood experiences), supports (e.g., social support, receiving needed help with daily living activities), and broader outcomes (e.g., quality of life, depression, anxiety). Longitudinal modeling supported autistic burnout as empirically distinct from, though related to, depression. ROC analysis (AUC = 0.89) supported cut-offs distinguishing probable (33-56, LR 7.38), unsure, and unlikely (0-22, LR 0.15) burnout. Conclusions: The AABM-R is a brief, accessible, psychometrically sound measure of autistic burnout suitable for heterogeneous autistic populations, with preliminary clinical cut-offs to guide screening. Further research is needed on the caregiver-report version and on longitudinal predictors and outcomes of burnout.

Background The global increase in autism spectrum disorder (ASD) diagnoses is expected to substantially increase demand for long-term rehabilitation services. However, little is known about how this increase affects rehabilitation service utilization and capacity in low- and middle-income countries. Methods We conducted a retrospective longitudinal study of children receiving developmental care at a tertiary rehabilitation center in Salvador, Brazil (2017-2026). Patients were classified into Childhood Autism, Other ASD, and non-ASD diagnostic groups according to ICD-10 diagnoses. Temporal trends in admissions and patients under follow-up were analyzed using generalized additive models and segmented Poisson regression. Factors associated with follow-up duration were evaluated using multivariable Cox proportional hazards models. Results Among 2,123 eligible children, 833 (39.2%) had Childhood Autism, 462 (21.8%) had Other ASD, and 828 (39.0%) had non-ASD diagnoses. Compared with children with non-ASD diagnoses, those with Childhood Autism entered care at younger ages, were predominantly male (77.9% vs. 57.2%), attended more visits, and remained under follow-up longer (all P<0.001). Admissions of children with Childhood Autism increased by 30.2% annually before 2023 but declined thereafter (-19.6% annually; P<0.001). Despite this decline, the number of children with Childhood Autism receiving ongoing rehabilitation continued to increase, reflecting prolonged follow-up. In adjusted analyses, Childhood Autism was associated with a substantially lower hazard of reaching the last recorded follow-up visit than non-ASD diagnoses (adjusted hazard ratio, 0.35; 95% CI, 0.30-0.40; P<0.001). Conclusions The rapid increase in ASD admissions fundamentally reshaped rehabilitation service utilization. Because children with ASD remained under follow-up substantially longer than those with other developmental conditions, they accounted for an increasing share of the rehabilitation caseload, even after new admissions began to decline. These findings highlight the importance of planning rehabilitation services according to both new admissions and the cumulative demand generated by long-term follow-up.

Background: Altered gamma-aminobutyric acid (GABA) neurotransmission is a proposed mechanism underlying autism spectrum disorder (ASD), prompting evaluation of several GABA-modulating pharmacotherapies. However, it remains unclear whether these interventions improve ASD broadly or preferentially affect specific symptom domains. Methods: We conducted a systematic review and random-effects meta-analysis of randomized controlled trials evaluating GABA-modulating pharmacotherapies in individuals with ASD. PubMed/MEDLINE, Embase, Scopus, and CENTRAL were searched from inception to April 1, 2026. Outcomes were prespecified as global autism severity, social communication, functional communication, restricted and repetitive behaviours (RRBs), adaptive behaviour, and irritability. Risk of bias was assessed using the Cochrane Risk of Bias 2 tool, and certainty of evidence was evaluated using GRADE. Results: Thirteen randomized controlled trials evaluating three GABA-modulating interventions (bumetanide, arbaclofen, and valproate) were included. GABA-modulating therapies were associated with statistically significant improvements in global autism severity (Hedges' g = -0.25, 95% CI -0.46 to -0.03; p = 0.028) and adaptive behaviour (Hedges' g = -0.09, 95% CI -0.15 to -0.02; p = 0.023). No significant pooled effects were observed for social communication (Hedges' g = -0.26, p = 0.077), functional communication (Hedges' g = -0.01, p = 0.869), RRBs (Hedges' g = -0.21, p = 0.126), or irritability (Hedges' g = -0.07, p = 0.543). After Holm-Bonferroni step down procedure, neither global autism severity nor adaptive behaviour remained statistically significant (Holm-adjusted p = .140 and .138, respectively). Adverse events were predominantly gastrointestinal, neurological, metabolic, and appetite-related. Overall risk of bias was variable, and the certainty of evidence ranged from very low to moderate. Conclusions: GABA-modulating pharmacotherapies did not demonstrate a robust, multiplicity-corrected benefit in any of the six prespecified ASD symptom domains. Nominal, unadjusted improvements in global autism severity and adaptive behaviour did not withstand correction for multiple comparisons and should be regarded as hypothesis-generating rather than confirmatory. Larger, adequately powered randomized trials using standardized domain-specific outcome measures are needed to determine whether individual GABA-modulating agents provide clinically meaningful benefit.

Primary ciliary dyskinesia (PCD) is a rare, genetic, multiorgan disease requiring lifelong management. Although PCD affects everyday life, little is known about how people with PCD experience social functioning (SF). We conducted a study within the international participatory Living with PCD study to comprehensively explore SF. First, we conducted a focus group and two semi-structured interviews with adults and parents of people with PCD. We analysed qualitative data thematically and used the findings to develop a multilingual online questionnaire on SF. The questionnaire was completed by 277 participants: 225 adults and adolescents with PCD (81%) and 52 parents of children with PCD (19%). Participants reported active social lives and strong close relationships. PCD had a positive impact on family relationships for 39% of adult/adolescent participants and 41% of parents reporting for children. Among adult/adolescent participants, 49% reported positive or no impact on romantic/intimate relationships, while 17% had avoided or ended a relationship because of PCD. PCD affected the ability to meet responsibilities for 54% of participants, free time for 58%, and planning effort for 53%. Participants were more comfortable discussing PCD with family, friends, and partners than in work or educational settings, where only 29% reported receiving support. Financial support, flexible work, or educational policies and better-trained healthcare professionals were the most frequently identified unmet needs. This study suggests that maintaining SF with PCD requires substantial individual and relational work. Improving SF for people with PCD requires systemic responses in healthcare, education, and employment, alongside support from close networks.

Gastrointestinal (GI) conditions are common among children with neurodevelopmental disabilities (NDDs), and are associated with functional impairment, behavioral symptoms, and increased health care utilization. A unique relationship between autism and GI dysfunction has been proposed, leading to a focus on autism in GI research, management guidelines, and clinical tool development. Leveraging >20 years of electronic health record data and a cohort of 42,204 cases with attention-deficit/hyperactivity disorder, autism, cerebral palsy, epilepsy, or intellectual disability and 297,402 controls without NDDs, we quantified associations between NDDs and GI conditions in children. GI conditions were more common in cases than controls across all individual NDDs; intellectual disability and cerebral palsy were most strongly associated with having a GI condition. In this work, clinically recognized GI morbidity was elevated across all NDDs and not unique to autism, suggesting that a broader, transdiagnostic approach to GI dysfunction in children with NDDs is warranted.

Objectives To evaluate the positive and adverse effects of parent-mediated interventions (PMIs) versus care as usual for children with autism. Setting Systematic review and meta-analysis and Trial Sequential Analyses (TSA), following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Methods We searched for randomised clinical trials of PMIs for children with autism in the databases CENTRAL, EMBASE, LILACS, PsycINFO, MEDLINE, and SCI-EXPANDED (up to 13 August, 2025), complemented with manual searches. 12,359 articles were screened. Data were synthesised using meta-analyses and Trial Sequential Analyses (TSA), and risks of bias and certainty of the evidence were evaluated. Primary and secondary outcome measures The primary outcome was autism characteristics. Secondary outcomes were adverse effects, child adaptive functioning, child language, child and parent quality of life, and parental stress. Ten exploratory outcomes were included. Results 32 trials (N=1,625) comparing PMIs to usual care, waiting list, or no intervention were included. All trials had a high risk of bias. The multiplicity-adjusted threshold for statistical significance was p = 0.013 due to the number of outcomes. Meta-analyses and TSAs showed it could be rejected that PMIs reduced autism characteristics (MD = -0.88; 95% confidence interval -2.92 to 1.15; p = 0.05, 4 trials, N=353, low certainty), child adaptive functioning (7 trials, N=408), child language (4 trials, N=308), or parental stress (7 trials, N=385). Due to insufficient data, the remaining secondary meta-analyses could not be conducted. Meta-analyses of exploratory outcomes showed beneficial effects concerning child behaviour problems and parent sensitivity/synchronicity. Conclusions This meta-analysis found no benefits of PMIs on child autism characteristics, child adaptive functioning, child language, or parental stress. Benefits were found in reduction of child behaviour problems and improved parent sensitivity/synchronicity. The evidence remains uncertain, and more trials including outcomes of adverse effects and quality of life are needed.

A body of research suggests that autistic individuals are less likely to drink alcohol than neurotypicals. However, emerging studies support a link between autism and alcohol use. This complex relationship is also reflected in studies that have examined the genetic overlap between the two traits. However, it is unclear whether there is a direct causal relationship between them. To explore this, we applied a combination of polygenic score and Mendelian randomisation analyses using publicly available genome-wide summary statistics and phenotypic measures of autism and alcohol consumption from UK Biobank. LD score regression analyses did not provide evidence of a genetic correlation between genetic liability for autism and drinks consumed per week (rg=-0.08; CI95%=-0.19, 0.03). Further, findings from polygenic score analyses did not support an association between genetic liability for autism and overall monthly alcohol intake. Univariable Mendelian randomisation analyses showed little evidence for a total effect of autism, attention deficit hyperactivity disorder (ADHD) or depression on overall monthly alcohol consumption. Multivariable Mendelian randomisation analyses also showed little evidence of a direct effect of autism on drinks per week when controlling for ADHD and depression. It is plausible that genetic liability for autism does not directly increase the amount of alcohol consumed but instead operates via commonly co-occurring difficulties in the autistic community. However, our findings may be due to methodological shortcomings, including weak instruments biasing effects towards to the null. Consequently, results should be interpreted with caution and further research conducted to address these issues.

Background Elevated resting gamma power is a reproducible, robust neurophysiology marker across species in fragile X syndrome (FXS), a major known cause of autism spectrum disorders (ASD). In FXS, this neurophysiological phenotype is well described and particularly prominent in males harboring fully methylated full CGG repeat expansions. However, gamma power evaluations in idiopathic ASD have yielded variable results. As a single-gene model of ASD, FXS hold promise to biologically model some of the autism spectrum. Exaggerated gamma power in FXS is thought to reflect increased cortical excitability, a common feature of ASD, and has been shown to correlate with symptoms in both human FXS individuals and the Fmr1 knockout mouse model of FXS. A recent clinical trial of the BK channel positive modulator, Codabakalner, provided encouraging signs that normalization of gamma power in FXS may provide therapeutic benefit [14]. Interventional and biomarker studies in ASD provide support that this may also be the case in ASD. We utilized gamma band power to evaluate neurophysiological overlap between ASD and FXS seeking to determine the prevalence and clinical characteristics of those with ASD who exhibit a FXS-like elevated resting state gamma phenotype. Methods This cross-sectional resting EEG analysis included 159 individuals with non-syndromic ASD and 41 males with fully methylated full mutation FXS. Relative gamma power was calculated as 30-100 Hz power divided by 1-100 Hz power across 10-20-equivalent electrodes, excluding 55-65 Hz. We defined the cutoff for elevated resting gamma band power in ASD as relative gamma power of greater than or equal to the median minus one standard deviation of gamma power in our FXS male sample. Results A FXS-derived relative-gamma threshold of 0.185 or greater was met by 22% of participants with ASD (n=35). As expected, the mean ASD group resting state gamma was lower than the male FXS sample (p < 0.001). ASD participant threshold proportions by age group were 3/37 (8.1%) below 13 years, 9/50 (18.0%) age 13-18 years, and 23/72 (31.9%) in the 18+ years group. Within the ASD group, there were no observable clinical characteristics that readily differentiated participants with an elevated gamma phenotype from those without this phenotype. Conclusions Approximately one fifth of all participants and slightly over 30 percent of adults with ASD met the FXS-derived elevated resting gamma band power criterion. This represents the first investigation using a translational brain neurophysiology marker in a syndromic form of autism to parse a clinical idiopathic ASD sample to identify potential overlapping brain features. The results will work to support potential targeting of ASD subgroups in the future utilizing therapeutic approaches initially established in a single-gene form of developmental disability.

Background Psychiatric diagnoses and psychotropic medication use among children, adolescents, and young adults have increased in high-income countries, with concerns about geographic variation. We described national trends and geographic variation in Denmark from 2010 to 2025 and developed an interactive online tool to explore these patterns. Methods We conducted a nationwide, descriptive, repeated cross-sectional register-based study of all Danish residents aged 0-24 years in 2010-2025 (n=2,930,744), using the Danish National Patient Registry and the Danish National Prescription Registry. We estimated annual incidence, prevalence, and, for selected diagnoses, lifetime prevalence, by age and sex, and age- and sex-standardised rates across regions, health councils, and municipalities. We assessed geographic variation using deviations from national means, coefficients of variation, Gini coefficients, and funnel plots. Findings Psychiatric diagnoses and psychotropic medication use increased from 2010 to 2025. The annual prevalence of attention-deficit hyperactivity disorder (ADHD) increased from 0.41 to 2.3 per 100 individuals, autism spectrum disorders from 0.20 to 1.2, and melatonin use from 0.14 to 3.0. ADHD and autism spectrum disorders were more prevalent among boys and anxiety disorders among girls. Sertraline use was also more prevalent among girls. Geographic variation was observed across diagnoses and psychotropic medications at regional, health council, and municipal levels. For example, lifetime prevalence of autism ranged from 1.3 to 5.9 per 100 across municipalities, and in 2025 regional coefficients of variation ranged from 0.11 (sertraline) to 0.41 (atomoxetine). Results can be explored in the interactive online tool (https://bupstat.sdu.dk/?lang=en). Interpretation Psychiatric diagnoses and psychotropic medication use increased among Danish children, adolescents, and young adults, with marked geographic variation. Descriptive data cannot establish the causes of this variation, but the findings identify areas for further review and support continued monitoring. Funding Best for Us project (www.bedstforos.dk), funded by the Novo Nordisk Foundation (NNF24SA0093635) and the Obel Family Foundation (69348).

Pharmacological treatments targeting core autistic features remain limited. In neurotypical adults, cannabidiol (CBD) alters mismatch negativity (MMN), an electrophysiological marker of automatic auditory deviance detection that has been associated with autistic traits. The effects of CBD on MMN, as measured using electroencephalography (EEG), in autistic children remain unknown. This secondary analysis of a pilot randomised, double-blind, placebo-controlled crossover trial examined the effects of 12 weeks of oral CBD oil on MMN during a duration-deviant auditory oddball task. We hypothesised that CBD would produce more negative MMN amplitudes and shorter peak latencies relative to placebo. Nineteen autistic children (6-12 years, 8 female) received CBD (dose) and placebo in randomised order, separated by an 8-week washout. Age-adjusted linear mixed-effects models tested Time (baseline, follow-up) x Treatment (CBD, placebo) effects on mean MMN amplitude and peak latency separately at Fz and FCz. Exploratory Spearman correlations examined baseline associations between MMN and Developmental Behaviour Checklist-2 (DBC-2) Social Relating scores. At FCz, latency decreased following CBD but increased following placebo but did not survive FDR correction (p = .029, pFDR = .058) and no other interactions were significant. Higher baseline DBC-2 Social Relating scores were associated with more negative MMN amplitude at FCz (rho = -.58, pFDR = .028) and Fz (rho = -.59, pFDR = .028). These findings provide tentative evidence that CBD may modulate MMN latency in autistic children. Larger trials should clarify CBDs effects on MMN and further examine the association between MMN amplitude and social-relating difficulties.