Child Characteristics Associated with Motivational Biases and Diagnostic Stability of ASD in the First Three Years of Life

Background: Research from retrospective studies has suggested that child characteristics associated with motivational style may be related to symptom onset and expression in children with Autism Spectrum Disorders (ASDs). These suggestions have recently received support from prospective studies with high-risk infant sibling cohorts. Specifically, among children who received a diagnosis of an ASD at 36 months, those who were rated by their parents as high approach were identified later (after 14 months), when compared to their high withdrawal counterparts (identified by 14 months), (Garon et al., 2009). Novel to this line of research is the investigation of the association between child characteristics and symptom course and expression as assessed via clinical impression of ASD diagnosis, over the first three years of life.

Objectives: The association of diagnostic stability and child characteristics (i.e., temperament traits and communicative style) was assessed. Diagnostic impression data were reviewed across study time points (14, 18, 24, 30, and 36 months) and stability ratings were assigned for 38 children with ASD. Diagnostic stability was operationalized as consistent ASD impression based on clinician ratings across all available data points. Subjects who were inconsistently rated as ASD positive or who received the diagnosis after 14 months of age were classified as having unstable diagnosis. Children with unstable profiles were expected to show more approach-oriented temperament traits (e.g., high approach, activity) and more frequent communicative behaviors.

Methods: Data on temperament characteristics were collected via parent report on the Toddler Temperament Scale (TTS) at 24 months of age. Behavioral assessment of communicative style was measured using the Communication and Symbolic Behavior Scales, Developmental Profile (CSBS DP) at 24 months. A Social Approach composite was computed by adding total frequency scores of behavioral regulatory communicative acts and shared positive affect. The Mullen Scales of Early Learning, Early Learning Composite (ELC) score was used as a covariate in all analyses given group differences on this measure (i.e., unstable diagnosis group demonstrated significantly higher ELC scores).

Results: Results indicated that children with unstable diagnostic profiles were rated by their parents as more distractible to extraneous environmental stimuli when compared to children with stable ASD profiles (TTS, Distractibility Scale, F (3, 35) = 8.48, p = .006). Additional analyses indicated that an unstable ASD diagnostic profile was associated with more social communication bids when compared to children with stable profiles (CSBS DP, Social Approach Composite, F (3, 35) = 4.24, p = .047).

Conclusions: This study suggests that child characteristics associated with motivational biases are meaningfully related to symptom course and expression as assessed by using clinician impression data. Children with unstable diagnostic impressions were more effectively (easily) distractible by extraneous environmental stimuli and more engaged communicatively both to share positive affect and regulate examiner behavior (e.g., requesting, refusing). Interestingly, frank motivational differences (approach vs. avoidance) were not apparent based on parent report, but were reflected in behavioral observation data of communicative style.