Characterizing Repetitive, Stereotyped, and Sensory Behaviors in Toddlers with Autism, Developmental Delay and Typical Development

Background: Repetitive/stereotyped behaviors are crucial to the diagnosis of autism. However, data are needed to clarify the specificity of these features to autism and to evaluate the validity of assessment strategies in young children.

Objectives:   We sought to characterize repetitive/stereotyped behaviors and sensory issues in toddlers with autism (n=60), developmental delays (DD; n=21), and typical peers (n=20). Among children with autism, we examined the association between repetitive behaviors, sensory issues, social impairment, and cognitive functioning. Finally, we examined correlations between parent reported repetitive behaviors and examiner observation.

Methods:   Participants included toddlers ages 18-30 months recruited from community pediatricians and agencies.  Participants were evaluated for autism using the ADOS-Module 1 and ADI-R Toddler. Repetitive behaviors and sensory issues were assessed using parent reports on the Repetitive Behavior Scale (RBS) and the Short Sensory Profile (SSP), and with examiner ratings on the ADOS.  Cognitive ability was assessed using the Mullen Scales.

Results:   Toddlers with autism exhibited more repetitive behaviors than children in the DD (p<0.01) and typically developing groups (p<0.01).  Toddlers with autism showed more sensory issues than typical peers (p<.01), but this did not distinguish children with autism from those with DD.  In the autism group, repetitive behaviors were predictive of greater social impairment on the ADI-R and ADOS and lower cognitive scores on the Mullen. Parent report and examiner observations of repetitive behavior were moderately correlated (r = .28 to .489). 

Conclusions:   Repetitive behaviors differentiated toddlers with autism from those with DD and typical peers, and were associated with greater impairment within the autism group.  Toddlers with autism and DD both displayed more sensory issues than typical peers. Clinically, this suggests that repetitive behaviors, but not sensory issues, are important in distinguishing toddlers with autism versus DD. Parent report was correlated with clinician ratings, suggesting utility for initial screening.