Children are receiving diagnoses of autism spectrum disorder (ASD) at earlier ages and the American Academy of Pediatrics recommends that all children be screened for ASD at 18 and 24 months. Therefore, research about the early diagnostic features of ASD is increasingly important. Since DSM-IV-TR criteria were developed before the diagnosis of toddlers was common, it is important to examine the utility of DSM-IV-TR criteria with a young sample of toddlers with ASD.
The purpose of this study was 1) to describe the diagnostic features of a sample of 18-24 month old toddlers with ASD using DSM-IV-TR criteria, and 2) to compare clinical observation and parent report of core diagnostic features of ASD.
Children were recruited by the FIRST WORDS® Project from a general population sample using a broadband screener for communication delays followed by an autism-specific screener. Children participating in this study were diagnosed with ASD (n=60) before 24 months of age. Measures of early diagnostic features of ASD were derived from each child’s initial diagnostic assessment which included a clinical observation using the Autism Diagnostic Observation Schedule-Toddler Module (ADOS-T: Luyster et al., 2009) and parent report of symptoms using the Early Screening for Autism and Communication Disorders (ESAC; Wetherby, Woods, & Lord). Items from the ADOS-T and ESAC were delineated by DSM-IV-TR domains and diagnostic features.
A preliminary analysis was completed on 47 children between 15-24 months (M=19.3, SD=1.76). The majority of children showed three of the diagnostic features in the DSM Social Interaction domain— shared enjoyment (95%), social-emotional reciprocity (95%), and multiple nonverbal behaviors (94%), but difficulty with peer relationships was infrequent (13%). In the Communication domain, the majority of children showed all four diagnostic features- spoken language (98%), symbolic play (98%), reciprocal communication (92%) and repetitive language (83%). In the Repetitive Behavior domain, restricted interests (95%), rituals and routines (78%) and preoccupation with parts of objects (70%) were common while stereotyped mannerisms (43%) were less frequent. Agreement between parent and clinical observations for diagnostic features was examined by DSM domain. Preliminary results suggest fair to moderate agreement between parent and clinician reports in the Social and Communication domains. Agreement between parent and clinician report was weaker in the Repetitive Behavior domain.
Preliminary analyses indicate that these toddlers with ASD exhibited diagnostic features in all three DSM-IV-TR domains. Features in Social Interaction and Communication domains were most common while Repetitive Behavior features were less frequent but present in most of these toddlers. As expected, difficulty with peer relationships was not a common feature in toddlers with ASD. These findings add to existing research examining the early ASD phenotype and document the utility of DSM-IV-TR criteria for very young toddlers. Further research is needed to examine the frequency of these diagnostic features in toddlers without ASD to ensure specificity of diagnostic criteria. These results provide important information for consideration in the upcoming revision of diagnostic criteria for the DSM-V.