Differentiating autism spectrum disorder from other developmental delays in the first two years of life.

Advances in the identification of the early signs of autism spectrum disorder (ASD) have occurred despite the heterogeneity of the disorder and its variable onset and presentation. Using various methodologies including retrospective studies, community samples, and sibling cohorts, researchers have identified behavioral markers of the disorder that emerge over the first 2 years of life. However, there are characteristics of ASD that overlap with other types of developmental delay (DD), which may complicate differential diagnosis in young children. A review of the literature was conducted to identify the most promising behavioral markers that distinguish ASD from other types of DD in the first 2 years of life. The review identified profiles of behavioral markers in the social realm by 12 months and in the communication realm by 18 months, which along with additional atypical motor behaviors could distinguish ASD from DD. This constellation of features coupled with a flat or declining trajectory in specific aspects of social and communication development, may assist clinicians in targeting early interventions to at-risk infants.

Early language and communication development of infants later diagnosed with autism spectrum disorder.

It is well recognized that delayed "first words" is among the most common presenting symptoms of autistic spectrum disorders (ASD). However, data on earlier language and communication development in children with ASD are limited to retrospective reports from parents and from home videos. In this study, we prospectively collected parent report data on early communication and language development in 97 infant siblings of children with ASD and 49 low-risk controls. Parents completed the MacArthur Communicative Development Inventory--Infant Form at 12 and 18 months. Analysis compared 3 groups defined on the basis of diagnostic assessment at 24 months: (1) siblings with ASD (n = 15), (2) siblings not meeting diagnostic criteria for ASD (n = 82), and (3) low-risk controls, none of whom had ASD (n = 49). Children with ASD showed delays in early language and communication compared with non-ASD siblings and controls. At 12 months, the ASD group was reported to understand significantly fewer phrases and to produce fewer gestures. At 18 months, they showed delays in their understanding of phrases, comprehension and production of single words, and use of gestures. Siblings not diagnosed with ASD also used fewer play-related gestures at 18 months than low-risk controls, even when children with identified language delays were excluded. Overall, this prospective study confirms that delays in communication and language development are apparent early in life in children with ASD, and emphasizes that developmental surveillance should include monitoring for delays in gesture, which may be among the earliest signs of ASD.