Temperament Mediates the Relationship between Symptom Severity and Adaptive Functioning in School-Aged Children with Autism Spectrum Disorder
Objectives: The objective of this study was twofold: a) to identify subgroups of school-aged children with ASD with distinct temperament profiles; and b) to examine whether temperament subgroup membership mediates the relationship between ASD symptom severity and adaptive functioning outcomes.
Methods: Data came from the Pathways in ASD study, a large Canadian longitudinal study of children with ASD. The sample was composed of 185 school-aged children with ASD at T1 (mean age: 7.8 years; males = 155). Temperament profile was indexed using the T1 Temperament in Middle Childhood Questionnaire (TMCQ). Children were followed over a 3-year period (T1-T3, with T1 as the first assessment between age 7-8 years and one assessment every 12 months for 2 consecutive years). Seventeen TMCQ dimension scores were used in hierarchical cluster analysis to derive subgroups of children. A test of binary mediation was conducted to test whether the relation between T2 autism symptom severity (Autism Diagnostic Observation Scale; ADOS) and T3 adaptive functioning level (Vineland Adaptive Behaviour Scale; VABS II) was mediated by a child’s temperament profile.
Results: A 2-cluster solution was selected as the best fit to the data; the two clusters were characterized by distinct temperament profiles (for most TMCQ dimensions). Compared to children in Cluster 2 (60.5% of sample), children in Cluster 1 (39.5% of sample) had higher scores on activation control, affiliation, assertiveness, attentional focusing, fantasy/openness, and soothability, and lower scores on anger/frustration, impulsivity, discomfort, fear, sadness, and shyness. Children in Cluster 1 had significantly lower adaptive functioning skills compared to children in Cluster 2 (F(1,165) = 44.98, p < 0.01). The total direct effect of ASD severity at T2 was a significant predictor of adaptive functioning outcome at T3, before entering the mediator variable (t(161) = - 3.51, p <0.001). The mediation test revealed that the total indirect effect for temperament profile was significant (p < 0.001; point estimate = -0.16, 95% CI = -0.41 to -0.13), and influenced the relation between ASD severity and adaptive functioning outcome.
Conclusions: Study findings show that in school-aged children with ASD, distinct temperament profiles influence the relation between ASD severity and adaptive functioning outcome. These findings suggest that temperament may be a previously under-researched but important child-level characteristic to consider when investigating developmental outcomes and intervention mechanisms in children with ASD.