Examining Temperament in a Longitudinal Study of High-Risk Infants for ASD

Background: Infant siblings of children with ASD experience a 2 to 50-fold increase in risk for developing autism. In the first year of life, high-risk infants who later go on to develop ASD may exhibit subtle disruptions in temperament that occur prior to the onset of clinical symptoms. A prospective study of infant siblings of children with ASD found that infants who were later diagnosed with ASD displayed higher levels of passivity and decreased activity at 6 months, atypical reactivity at 12 months of age (Zwaigenbaum et al., 2005), early irritability and proneness to distress and difficulty controlling attention and behavior at 24 months (Bryson et al., 2007; Garon et al., 2009). The present study represents one of the ongoing efforts to explore how temperament may influence the trajectory for high-risk infants.

Objectives: To examine temperament in high-risk and low-risk infants at 6 and 12 months of age. It is expected that by 12 months, the high-risk group will have lower positive affect, higher negative affect, and more difficulty regulating behavior on a parent report of temperament. The stability of temperament, as assessed via parent report, will be examined from 6 to 12 months as well as the relationship between temperament and early ASD risk symptoms at 12 months.

Methods: Participants included infant siblings of children with ASD (high-risk infants) and infant siblings of children without ASD (low-risk infants). Measures were administered at 6 and 12 months of age including a parent report of temperament, the Infant Behavior Questionnaire Revised (IBQ-R), a behavior observation of autism risk markers (the Autism Observation Scale for Infants (AOSI)), and a measure of cognition (the Mullen Scales of Early Learning).

Results: Preliminary results indicate no significant group differences on each factor of the IBQ-R at 6 or 12 months. Future analysis will include a larger sample and will examine the relationship between temperament domains on the IBQ-R and ASD risk symptoms at 12 months. Additional analyses will examine change scores from 6 to 12 months of age to look at the stability of parent report of temperament.

Conclusions: Preliminary results found no group differences of temperament at 6 months which is consistent with previous high-risk studies using parent report of temperament. The lack of group differences at 12 months may be due to the small sample size in the preliminary analysis. A larger sample is currently being obtained in which we expect that the high-risk group will reportedly have lower positive affect, higher negative affect, and more difficulty regulating behavior on the IBQ-R and that this temperament profile will be associated with symptom severity at 12 months as measured by the AOSI. The study of temperament in high-risk infants may help inform efforts aimed at the earlier identification and intervention of ASD.