Developmental course of autistic social impairment in males

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