Data from 10 sites of the NICHD/NIDCD Collaborative Programs of Excellence in Autism were combined to study the distribution of head circumference and relationship to demographic and clinical variables. Three hundred thirty-eight probands with autism-spectrum disorder (ASD) including 208 probands with autism were studied along with 147 parents, 149 siblings, and typically developing controls. ASDs were diagnosed, and head circumference and clinical variables measured in a standardized manner across all sites. All subjects with autism met ADI-R, ADOS-G, DSM-IV, and ICD-10 criteria. The results show the distribution of standardized head circumference in autism is normal in shape, and the mean, variance, and rate of macrocephaly but not microcephaly are increased. Head circumference tends to be large relative to height in autism. No site, gender, age, SES, verbal, or non-verbal IQ effects were present in the autism sample. In addition to autism itself, standardized height and average parental head circumference were the most important factors predicting head circumference in individuals with autism. Mean standardized head circumference and rates of macrocephaly were similar in probands with autism and their parents. Increased head circumference was associated with a higher (more severe) ADI-R social algorithm score. Macrocephaly is associated with delayed onset of language. Although mean head circumference and rates of macrocephaly are increased in autism, a high degree of variability is present, underscoring the complex clinical heterogeneity of the disorder. The wide distribution of head circumference in autism has major implications for genetic, neuroimaging, and other neurobiological research.

No abstract

In a multisite study of 351 children with autism spectrum disorders, 21 children with developmental delays, and 31 children with typical development, this study used caregiver interviews (i.e., the Autism Diagnostic Interview-Revised) at the time of entry into other research projects and follow-up telephone interviews designed for this project to describe the children's early acquisition and loss of social-communication milestones. Children who had used words spontaneously and meaningfully and then stopped talking were described by their caregivers as showing more gestures, greater participation in social games, and better receptive language before the loss and fewer of these skills after the loss than other children with autism spectrum disorders. A significant minority of children with autism without word loss showed a very similar pattern of loss of social-communication skills, a pattern not observed in the children with developmental delays or typical development.

Children with autism are often characterized as having abnormalities in auditory processing. This study examined automatic and active processing of simple auditory stimuli in children using a component of event related potentials, the mismatch negativity (MMN). Amplitude of MMN in children with autism was significantly smaller than in children with typical development in unattended conditions. However, children with autism exhibited a typical amplitude MMN when attending to the stimuli. Receptive language and MMN were not related in children with autism. Findings support the idea of abnormal automatic auditory processing by children with autism. Auditory discrimination of infrequent changes in streams of sounds appears to be accomplished through a different mechanism than in typical children, specifically through the investment of attention.

Autism is a developmental disorder marked by impairments in socialization, communication, and perseverative behavior and is associated with cognitive impairment and deficits in adaptive functioning. Research has consistently demonstrated that children with autism have deficits in adaptive functioning more severe than their cognitive deficits. This study investigates the correlates and predictors of adaptive functioning as measured by the Vineland Adaptive Behavior Scales in high- and low-functioning children with autism and their age and nonverbal IQ matched controls. Thirty-five 9-year-old children with high-functioning autism (HAD) were compared with 31 age-matched children with developmental language disorder (DLD), and 40 9-year-old children with low-functioning autism (LAD) were compared with 17 age-matched children with low IQ on adaptive functioning, IQ, autistic symptomology, and tests of language and verbal memory. Results indicate that both groups with autism were significantly impaired compared to their matched controls on Socialization and Daily Living, but not Communication and that these impairments were more pronounced in the HAD group than in the LAD group. Adaptive behavior was strongly correlated with autistic symptomology only in the HAD group. Regression analyses indicated that IQ was strongly predictive of adaptive behavior in both low-functioning groups, but tests of language and verbal memory predicted adaptive behavior in the higher functioning groups. Results suggest that IQ may act as a limiting factor for lower functioning children but higher functioning children are impaired by specific deficits, including autistic symptomology and impaired language and verbal memory.

No abstract

A multi-site study of 351 children with Autism Spectrum Disorders (ASD) and 31 typically developing children used caregiver interviews to describe the children's early acquisition and loss of social-communication milestones. For the majority of children with ASD who had experienced a regression, pre-loss development was clearly atypical. Children who had lost skills also showed slightly poorer outcomes in verbal IQ and social reciprocity, a later mean age of onset of autistic symptoms, and more gastrointestinal symptoms than children with ASD and no regression. There was no evidence that onset of autistic symptoms or of regression was related to measles-mumps-rubella vaccination. The implications of these findings for the existence of a 'regressive phenotype' of ASD are discussed.

Cluster analysis of test scores on expressive phonology and comprehension of words and sentences in 7-9-year-old children with preschool diagnosis of Autistic Disorder yielded 4 clusters. Cluster 1 (N = 11): phonology and comprehension both low; Cluster 2 (N = 4): phonology low, near average comprehension; Cluster 3 (N = 40): average phonology, comprehension low to low average; Cluster 4 (N = 7): average or better phonology and comprehension. The clusters support two major types of language disorders in autism driven by impaired expressive phonology, each divisible by comprehension ability. The clusters refute a single language disorder in autism and are consonant with earlier-defined clinical subtypes.