Frequency and pattern of documented diagnostic features and the age of autism identification

Objective: The DSM-IV-TR specifies 12 behavioral features that can occur in hundreds of possible combinations to meet diagnostic criteria for autism spectrum disorder (ASD). This paper describes the frequency and variability with which the 12 behavioral features are documented in a population-based cohort of 8-year-old children under surveillance for ASD, and examines whether documentation of certain features, alone or in combination with other features, is associated with earlier age of community identification of ASD.

Method: Statistical analysis of behavioral features documented for a population-based sample of 2,757 children, 8 years old, with ASD in 11 geographically-defined areas in the US participating in the Autism and Developmental Disabilities Monitoring Network in 2006.

Results: The median age at ASD identification was inversely associated with the number of documented behavioral features, decreasing from 8.2 years for children with only seven behavioral features to 3.8 years for children with all 12. Documented impairments in nonverbal communication, pretend play, inflexible routines, and repetitive motor behaviors were associated with earlier identification, whereas impairments in peer relations, conversational ability, and idiosyncratic speech were associated with later identification.

Conclusions: The age dependence of some of the behavioral features leading to an autism diagnosis, as well as the inverse association between age at identification and number of behavioral features documented, have implications for efforts to improve early identification. Progress in achieving early identification and provision of services for children with autism may be limited for those with fewer ASD behavioral features, as well as features likely to be detected at later ages

Importance: The DSM-5 contains revised diagnostic criteria for autism spectrum disorder (ASD) from the DSM-IV-TR. Potential impacts of the new criteria on ASD prevalence are unclear.

Objective: To assess potential effects of the DSM-5 ASD criteria on ASD prevalence estimation by retrospectively applying the new criteria to population-based surveillance data collected for previous ASD prevalence estimation.

Design, setting, and participants: Cross-sectional, population-based ASD surveillance based on clinician review of coded behaviors documented in children’s medical and educational evaluations from 14 geographically defined areas in the United States participating in the Autism and Developmental Disabilities Monitoring (ADDM) Network in 2006 and 2008. This study included 8-year-old children living in ADDM Network study areas in 2006 or 2008, including 644 883 children under surveillance, of whom 6577 met surveillance ASD case status based on the DSM-IV-TR.

Main outcomes and measures: Proportion of children meeting ADDM Network ASD criteria based on the DSM-IV-TR who also met DSM-5 criteria; overall prevalence of ASD using DSM-5 criteria.

Results: Among the 6577 children classified by the ADDM Network as having ASD based on the DSM-IV-TR, 5339 (81.2%) met DSM-5 ASD criteria. This percentage was similar for boys and girls but higher for those with than without intellectual disability (86.6% and 72.5%, respectively; P < .001). A total of 304 children met DSM-5 ASD criteria but not current ADDM Network ASD case status. Based on these findings, ASD prevalence per 1000 for 2008 would have been 10.0 (95% CI, 9.6-10.3) using DSM-5 criteria compared with the reported prevalence based on DSM-IV-TR criteria of 11.3 (95% CI, 11.0-11.7).

Conclusions and relevance: Autism spectrum disorder prevalence estimates will likely be lower under DSM-5 than under DSM-IV-TR diagnostic criteria, although this effect could be tempered by future adaptation of diagnostic practices and documentation of behaviors to fit the new criteria.

Although social impairments are considered the hallmark deficit of autism, many behavioral intervention studies rely on cognitive functioning as a primary outcome. Fewer studies have examined whether changes in cognition are associated with changes in social functioning. This study examined whether cognitive gains among 192 students from 47 kindergarten-through-second-grade autism support classrooms participating in a year-long behavioral intervention study were associated with gains in social functioning. Children’s gains in cognitive ability were modestly associated with independent assessors’ and teachers’ evaluations of social functioning but were not associated with changes in parent ratings. Observed social gains were not commensurate with gains in cognition, suggesting the need both for interventions that directly target social functioning and relevant field measures of social functioning.

Keywords: autism spectrum disorder; intervention; social deficits.

Most recent estimates indicate that 1 in 68 children are affected by an autism spectrum disorder (ASD). Though decades of research have uncovered much about these disorders, the pathological mechanism remains unknown. Hampering efforts is the seeming inability to integrate findings over the micro to macro scales of study, from changes in molecular, synaptic and cellular function to large-scale brain dysfunction impacting sensory, communicative, motor and cognitive activity. In this review, we describe how studies focusing on neuronal circuit function provide unique context for identifying common neurobiological disease mechanisms of ASD. We discuss how recent EEG and MEG studies in subjects with ASD have repeatedly shown alterations in ensemble population recordings (both in simple evoked related potential latencies and specific frequency subcomponents). Because these disease-associated electrophysiological abnormalities have been recapitulated in rodent models, studying circuit differences in these models may provide access to abnormal circuit function found in ASD. We then identify emerging in vivo and ex vivo techniques, focusing on how these assays can characterize circuit level dysfunction and determine if these abnormalities underlie abnormal clinical electrophysiology. Such circuit level study in animal models may help us understand how diverse genetic and environmental risks can produce a common set of EEG, MEG and anatomical abnormalities found in ASD.

Keywords: ASD; EEG; MEG; VSDi; circuit; gamma; neurophysiology; translational.

Approximately 30% of hearing children with autism spectrum disorder (ASD) do not acquire expressive language, and those who do often show impairments related to their social deficits, using language instrumentally rather than socially, with a poor understanding of pragmatics and a tendency toward repetitive content. Linguistic abnormalities can be clinically useful as diagnostic markers of ASD and as targets for intervention. Studies have begun to document how ASD manifests in children who are deaf for whom signed languages are the primary means of communication. Though the underlying disorder is presumed to be the same in children who are deaf and children who hear, the structures of signed and spoken languages differ in key ways. This article describes similarities and differences between the signed and spoken language acquisition of children on the spectrum. Similarities include echolalia, pronoun avoidance, neologisms, and the existence of minimally verbal children. Possible areas of divergence include pronoun reversal, palm reversal, and facial grammar.