Longitudinal Changes in the Expression of Autism Spectrum Disorders in Girls and Boys

Abstract

Few studies have examined sex differences in autism spectrum disorders (ASD) and none have used a longitudinal model. It is often difficult for studies to gather data on large samples of females with ASD across multiple time points, due to the prevalence differences between males and females with ASD. Developmental level, adaptive functioning, and ASD symptom profiles were examined across two time points (approximately two and four years of age) in 28 girls and 128 boys with a stable diagnosis of ASD. Data on cognitive and adaptive functioning suggest minimal differences between males and females with ASD at this young age, despite contradictory previous findings in older children. Neither were there many interaction effects between time point and sex nor differences in rates of increasing or decreasing performance. Autism severity was similar, although there were slight differences on overall severity or interactions between sex and time point depending on which measures of severity were used. Environmental influences and potential developmental pathways are discussed.