Taken together with previous findings, these results support the notion that genetic susceptibility factors responsible for common, subsyndromal social impairments may be related to the causes of categorically defined pervasive developmental disorders.

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Background Recent research has suggested that autistic social impairment (ASI) is continuously distributed in nature, and that subtle autistic-like social impairments aggregate in the family members of children with pervasive developmental disorders (PDDs). This study examined the longitudinal course of quantitatively-characterized ASI in 3 to 18 year old boys with and without PDD. Methods We obtained assessments of 95 epidemiologically ascertained male-male twin pairs and a clinical sample of 95 affected children using the Social Responsiveness Scale (SRS), at two time points, spaced 1–5 years apart. Longitudinal course was examined as a function of age, familial loading for PDD, and autistic severity at baseline. Results Inter-individual variation in SRS scores was highly preserved over time, with test-retest correlation of 0.90 for the entire sample. SRS scores exhibited modest general improvement over the study period; individual trajectories varied as a function of severity at baseline and were highly familial. Conclusion Quantitative measurements of ASI reflect heritable trait-like characteristics. Such measurements can serve as reliable indices of phenotypic severity for genetic and neurobiologic studies, and have potential utility for ascertaining incremental response to intervention.

Deficits in reciprocal social behavior are a characterizing feature of autism spectrum disorder (ASD). Autism‐related variation in reciprocal social behavior (AVR) in the general population is continuously distributed and highly heritable—a function of additive genetic influences that overlap substantially with those which engender clinical autistic syndromes. This is the first long‐term prospective study of the stability of AVR from childhood through early adulthood, conducted via serial ratings using the Social Responsiveness Scale, in a cohort‐sequential study involving children with ASD, other psychiatric conditions, and their siblings ( N = 602, ages = 2.5–29). AVR exhibits marked stability throughout childhood in individuals with and without ASD.

Autism spectrum disorders (ASDs) are characterized by correlated deficiencies in social and language development. This study explored a fundamental aspect of auditory information processing (AIP) that is dependent on social experience and critical to early language development: the ability to compartmentalize close-sounding speech sounds into singular phonemes. We examined this ability by assessing whether close-sounding non-native language phonemes were more likely to be perceived as disparate sounds by school-aged children with high-functioning ASD (n = 27), than by unaffected control subjects (n = 35). No significant group differences were observed. Although earlier in autistic development there may exist qualitative deficits in this specific aspect of AIP, they are not an enduring characteristic of verbal school-aged children with ASD.