Temperament and Adaptive Functioning in a High-Risk Infant Sib Cohort
Siblings of children with Autistic Spectrum Disorder (ASD) have been found to be at higher risk of developing the disorder. As such this population provides a unique opportunity to investigate early mechanisms that influence the trajectory of individuals who develop ASD. Recent findings indicate that temperament may provide insight into the heterogeneous nature of ASD. Research supports a pattern of low positive affect, high negative affect and low regulation in prospective studies of high-risk infants subsequently diagnosed with ASD (Bryson et al., 2007; Garon et al., 2009). Notably, two studies have indicated that infants who are subsequently diagnosed with ASD show distinctive temperament trajectories in the first year of life (Clifford et al., 2013; del Rosario et al., 2014). Of interest for the current study, Evans and Rothbart (2009) have found evidence for two higher order temperament factors, which involve an integration of regulation and reactivity. Recently, Garon et al. (2015) have found differences in how these two main aspects of temperament were structured in a high risk population. In particular, Positive and Negative Affect factors at 24 months were positively associated with one another in the high risk population while the association was non-significant for the low risk population.
The current study had two main objectives. The first was to determine the higher order factor structure of temperament in a high risk population. The second was to determine whether these high order temperament factors at 12 and 24 months predicted adaptive functioning at 5 years.
Infant siblings of children with ASD were assessed prospectively at 12 months on the Infant Behavior Questionnaire (IBQ) and at 24 months on the Toddler Behavior Assessment Questionnaire (TBAQ), both completed by parents. At 36 months, an independent ‘gold-standard’ diagnostic assessment for ASD was conducted including the Autism Diagnostic Observation Schedule (ADOS). At 5 years, parents completed the Vineland Adaptive Behavior Scale II (VABS-II). A confirmatory factor analysis (CFA) was used to derive two higher order temperament factors. A multivariate analysis of variance (MANOVA) was used to explore whether the temperament factors predicted different aspects of adaptive functioning. The dependent variables were VABS-II subscale scores while the independent variables were the two temperament factors and ASD symptoms as measured by the ADOS severity score at 36 months.
The hierarchical CFA resulted in two higher order temperament factors. The first factor labelled Regulation included significant loadings from the Positive Affect at 12 months, Positive Affect at 24 months, and Effortful Control at 24 months. The second factor, labelled Reactivity, included loadings from Negative Affect at 12 months, Negative Affect at 24 months and Positive Affect at 24 months. The MANOVA indicated that both Reactivity and Regulation made significant contributions to the prediction of adaptive function. Furthermore, these temperament factors remained significant predictors even when ASD symptoms at 36 months were included in the analysis.
The present findings highlight the importance of early temperament. Further, these results suggest that temperament provides additional information beyond that provided by early ASD symptoms.