Jeffrey Munson

Randomized, Controlled Trial of an Intervention for Toddlers With Autism: The Early Start Denver Model

OBJECTIVE: To conduct a randomized, controlled trial to evaluate the efficacy of the Early Start Denver Model (ESDM), a comprehensive developmental behavioral intervention, for improving outcomes of toddlers diagnosed with autism spectrum disorder (ASD). METHODS: Forty-eight children diagnosed with ASD between 18 and 30 months of age were randomly assigned to 1 of 2 groups: (1) ESDM intervention, which is based on developmental and applied behavioral analytic principles and delivered by trained therapists and parents for 2 years; or (2) referral to community providers for intervention commonly available in the community. RESULTS: Compared with children who received community-intervention, children who received ESDM showed significant improvements in IQ, adaptive behavior, and autism diagnosis. Two years after entering intervention, the ESDM group on average improved 17.6 standard score points (1 SD: 15 points) compared with 7.0 points in the comparison group relative to baseline scores. The ESDM group maintained its rate of growth in adaptive behavior compared with a normative sample of typically developing children. In contrast, over the 2-year span, the comparison group showed greater delays in adaptive behavior. Children who received ESDM also were more likely to experience a change in diagnosis from autism to pervasive developmental disorder, not otherwise specified, than the comparison group. CONCLUSIONS: This is the first randomized, controlled trial to demonstrate the efficacy of a comprehensive developmental behavioral intervention for toddlers with ASD for improving cognitive and adaptive behavior and reducing severity of ASD diagnosis. Results of this study underscore the importance of early detection of and intervention in autism.

Autism genome-wide copy number variation reveals ubiquitin and neuronal genes

Autism spectrum disorders (ASDs) are childhood neurodevelopmental disorders with complex genetic origins. Previous studies focusing on candidate genes or genomic regions have identified several copy number variations (CNVs) that are associated with an increased risk of ASDs. Here we present the results from a whole-genome CNV study on a cohort of 859 ASD cases and 1,409 healthy children of European ancestry who were genotyped with ∼550,000 single nucleotide polymorphism markers, in an attempt to comprehensively identify CNVs conferring susceptibility to ASDs. Positive findings were evaluated in an independent cohort of 1,336 ASD cases and 1,110 controls of European ancestry. Besides previously reported ASD candidate genes, such as NRXN1 (ref. 10) and CNTN4 (refs 11, 12), several new susceptibility genes encoding neuronal cell-adhesion molecules, including NLGN1 and ASTN2, were enriched with CNVs in ASD cases compared to controls (P = 9.5 × 10-3). Furthermore, CNVs within or surrounding genes involved in the ubiquitin pathways, including UBE3A, PARK2, RFWD2 and FBXO40, were affected by CNVs not observed in controls (P = 3.3 × 10-3). We also identified duplications 55 kilobases upstream of complementary DNA AK123120 (P = 3.6 × 10-6). Although these variants may be individually rare, they target genes involved in neuronal cell-adhesion or ubiquitin degradation, indicating that these two important gene networks expressed within the central nervous system may contribute to the genetic susceptibility of ASD.

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

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

Brain structural abnormalities in young children with autism spectrum disorder

Objective To explore the specific gross neuroanatomic substrates of this brain developmental disorder, the authors examine brain morphometric features in a large sample of carefully diagnosed 3- to 4-year-old children with autism spectrum disorder (ASD) compared with age-matched control groups of typically developing (TD) children and developmentally delayed (DD) children. Methods Volumes of the cerebrum, cerebellum, amygdala, and hippocampus were measured from three-dimensional coronal MR images acquired from 45 children with ASD, 26 TD children, and 14 DD children. The volumes were analyzed with respect to age, sex, volume of the cerebrum, and clinical status. Results Children with ASD were found to have significantly increased cerebral volumes compared with TD and DD children. Cerebellar volume for the ASD group was increased in comparison with the TD group, but this increase was proportional to overall increases in cerebral volume. The DD group had smaller cerebellar volumes compared with both of the other groups. Measurements of amygdalae and hippocampi in this group of young children with ASD revealed enlargement bilaterally that was proportional to overall increases in total cerebral volume. There were similar findings of cerebral enlargement for both girls and boys with ASD. For subregion analyses, structural abnormalities were observed primarily in boys, although this may reflect low statistical power issues because of the small sample (seven girls with ASD) studied. Among the ASD group, structural findings were independent of nonverbal IQ. In a subgroup of children with ASD with strictly defined autism, amygdalar enlargement was in excess of increased cerebral volume. Conclusions These structural findings suggest abnormal brain developmental processes early in the clinical course of autism. Research currently is underway to better elucidate mechanisms underlying these structural abnormalities and their longitudinal progression.

Early recognition of 1-year-old infants with autism spectrum disorder versus mental retardation

Previous work based on observations of home videotapes indicates that differences can be detected between infants with autism spectrum disorder and infants with typical development at 1 year of age. The present study addresses the question of whether autism can be distinguished from mental retardation by 1 year of age. Home videotapes of first birthday parties from 20 infants later diagnosed with autism spectrum disorder, 14 infants later diagnosed with mental retardation (without autism), and 20 typically developing infants were coded by blind raters with respect to the frequencies of specific social and communicative behaviors and repetitive motor actions. Results indicated that 1-year-olds with autism spectrum disorder can be distinguished from 1-year-olds with typical development and those with mental retardation. The infants with autism spectrum disorder looked at others and oriented to their names less frequently than infants with mental retardation. The infants with autism spectrum disorder and those with mental retardation used gestures and looked to objects held by others less frequently and engaged in repetitive motor actions more frequently than typically developing infants. These results indicate that autism can be distinguished from mental retardation and typical development by 1 year of age.

Parenting stress and psychological functioning among mothers of preschool children with autism and developmental delay

Parents of children with developmental disabilities, particularly autism spectrum disorders (ASDs), are at risk for high levels of distress. The factors contributing to this are unclear. This study investigated how child characteristics influence maternal parenting stress and psychological distress. Participants consisted of mothers and developmental-age matched preschool-aged children with ASD (N = 51) and developmental delay without autism (DD) ( N = 22). Evidence for higher levels of parenting stress and psychological distress was found in mothers in the ASD group compared to the DD group. Childrens problem behavior was associated with increased parenting stress and psychological distress in mothers in the ASD and DD groups. This relationship was stronger in the DD group. Daily living skills were not related to parenting stress or psychological distress. Results suggest clinical services aiming to support parents should include a focus on reducing problem behaviors in children with developmental disabilities.

Neurocognitive Function and Joint Attention Ability in Young Children with Autism Spectrum Disorder Versus Developmental Delay

Studies have shown that young children with autism are not impaired on prefrontal tasks relative to what would be expected for their mental age, raising questions about the executive dysfunction hypothesis of autism. These studies did not include ventromedial prefrontal tasks, however. The present study examined whether young children with autism spectrum disorder (ASD) are impaired on ventromedial prefrontal tasks, and whether performance on such tasks is correlated with a core autism symptom, joint attention ability. Seventy-two 3- to 4-year-old children with ASD, 34 3- to 4-year-old developmentally delayed children, and 39 12- to 46-month-old typically developing children, matched on mental age, were administered ventromedial and dorsolateral prefrontal tasks and joint attention tasks. Children with ASD performed similarly to comparison groups on all executive function tasks, indicating that at this early age, there is no autism-specific pattern of executive dysfunction. Ventromedial, but not dorsolateral, prefrontal task performance was strongly correlated with joint attention ability, however. The ventromedial prefrontal cortex is hypothesized to play a role in the development of joint attention and possibly some aspects of the autistic syndrome.

Neurocognitive and electrophysiological evidence of altered face processing in parents of children with autism: Implications for a model of abnormal development of social brain circuitry in autism

Neuroimaging and behavioral studies have shown that children and adults with autism have impaired face recognition. Individuals with autism also exhibit atypical event-related brain potentials to faces, characterized by a failure to show a negative component (N170) latency advantage to face compared to nonface stimuli and a bilateral, rather than right lateralized, pattern of N170 distribution. In this report, performance by 143 parents of children with autism on standardized verbal, visual-spatial, and face recognition tasks was examined. It was found that parents of children with autism exhibited a significant decrement in face recognition ability relative to their verbal and visual spatial abilities. Event-related brain potentials to face and nonface stimuli were examined in 21 parents of children with autism and 21 control adults. Parents of children with autism showed an atypical event-related potential response to faces, which mirrored the pattern shown by children and adults with autism. These results raise the possibility that face processing might be a functional trait marker of genetic susceptibility to autism. Discussion focuses on hypotheses regarding the neurodevelopmental and genetic basis of altered face processing in autism. A general model of the normal emergence of social brain circuitry in the first year of life is proposed, followed by a discussion of how the trajectory of normal development of social brain circuitry, including cortical specialization for face processing, is altered in individuals with autism. The hypothesis that genetic-mediated dysfunction of the dopamine reward system, especially its functioning in social contexts, might account for altered face processing in individuals with autism and their relatives is discussed.

Disruption at the PTCHD1 locus on Xp22.11 in autism spectrum disorder and intellectual disability

Mutations of the X-linked gene PTCHD1 are associated with autism spectrum disorders and intellectual disability. A Patch in the Fabric of Autism What causes autism? This disabling disorder is characterized by severe language and social impairment and is now included under the umbrella term “autism spectrum disorder” (ASD), which also includes milder deficits in communication and social development. Numerous theories have been advanced as to its causes. These have ranged from discredited concepts—“refrigerator” mothers and vaccines—to the modern idea of gene-environment interactions. Although no one gene simply explains the predisposition of patients for ASD, these disorders are wellknown to have a strong genetic component. Here, Noor et al. report the results of genetic analysis in thousands of patients and control subjects: Mutations at the PTCHD1 (patched-related gene) locus are associated with the inheritance of ASD and with intellectual disability in a small fraction of cases. In this study, the authors analyzed the PTCHD1 gene from 1896 patients with ASD and 246 with intellectual disability, and compared these to more than 10,000 control individuals, and found mutations in various parts of this gene in 25 affected individuals in 20 different families, but not in any of the controls. Some patients had large deletions, in one case spanning the entire gene, and in others the culprit was a missense mutation. A result of this gene’s location on the X chromosome, the affected patients were almost all male, and most had unaffected mothers and other female relatives. The authors also present evidence that the PTCHD1 gene may be part of the Hedgehog signaling pathway, which is important in embryonic development. Autism and intellectual disability are not straightforward disorders that can be attributed to mutations in a single gene. Even when candidate genes such as PTCHD1 are known, differences in the gene sequence do not perfectly correlate with phenotype, because there are many as yet undefined additional genes and environmental influences that dictate the ultimate characteristics of the person. Identifying some of these genes, as Noor et al. have done in this study, allows a better understanding of the disorder and the development of ways to compensate for its disabilities. Autism is a common neurodevelopmental disorder with a complex mode of inheritance. It is one of the most highly heritable of the complex disorders, although the underlying genetic factors remain largely unknown. Here, we report mutations in the X-chromosome PTCHD1 (patched-related) gene in seven families with autism spectrum disorder (ASD) and in three families with intellectual disability. A 167-kilobase microdeletion spanning exon 1 was found in two brothers, one with ASD and the other with a learning disability and ASD features; a 90-kilobase microdeletion spanning the entire gene was found in three males with intellectual disability in a second family. In 900 probands with ASD and 208 male probands with intellectual disability, we identified seven different missense changes (in eight male probands) that were inherited from unaffected mothers and not found in controls. Two of the ASD individuals with missense changes also carried a de novo deletion at another ASD susceptibility locus (DPYD and DPP6), suggesting complex genetic contributions. In additional males with ASD, we identified deletions in the 5′ flanking region of PTCHD1 that disrupted a complex noncoding RNA and potential regulatory elements; equivalent changes were not found in male control individuals. Thus, our systematic screen of PTCHD1 and its 5′ flanking regions suggests that this locus is involved in ~1% of individuals with ASD and intellectual disability.

Evidence for multiple loci from a genome scan of autism kindreds

We performed a genome-wide linkage scan using highly polymorphic microsatellite markers. To minimize genetic heterogeneity, we focused on sibpairs meeting the strict diagnosis of autism. In our primary analyses, we observed a strong linkage signal (P=0.0006, 133.16 cM) on chromosome 7q at a location coincident with other linkage studies. When a more relaxed diagnostic criteria was used, linkage evidence at this location was weaker (P=0.01). The sample was stratified into families with only male affected subjects (MO) and families with at least one female affected subject (FC). The strongest signal unique to the MO group was on chromosome 11 (P=0.0009, 83.82 cM), and for the FC group on chromosome 4 (P=0.002, 111.41 cM). We also divided the sample into regression positive and regression negative families. The regression-positive group showed modest linkage signals on chromosomes 10 (P=0.003, 0 cM) and 14 (P=0.005, 104.2 cM). More significant peaks were seen in the regression negative group on chromosomes 3 (P=0.0002, 140.06 cM) and 4 (P=0.0005, 111.41 cM). Finally, we used language acquisition data as a quantitative trait in our linkage analysis and observed a chromosome 9 signal (149.01 cM) of P=0.00006 and an empirical P-value of 0.0008 at the same location. Our work provides strong conformation for an autism locus on 7q and suggestive evidence for several other chromosomal locations. Diagnostic specificity and detailed analysis of the autism phenotype is critical for identifying autism loci.