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Thursday, May 7, 2009
Northwest Hall (Chicago Hilton)
2:30 PM
Background: Autistic spectrum disorders (ASD) are characterised by impairments in social interactions, communication and the presence of repetitive and ritualistic behaviors. However, in addition to these core symptoms, a large number of children with ASD experience significant internalizing difficulties such as anxiety and depression. Very little is known about the etiological relationship between internalizing symptoms and ASD. The emergence and stability of these symptoms during childhood and adolescence also remains poorly resolved.
Objectives: The current study aimed to investigate the relationship between ‘autistic-like’ and internalizing traits within a population-representative sample in middle to late childhood. We assessed whether autistic-like traits had a direct influence upon later internalizing difficulties or vice versa and analysed the etiological factors influencing the longitudinal association between these traits.
Methods: Data was taken from the UK-based Twins Early Development Study (TEDS). Data for this study included approximately 5000 twin pairs assessed at ages 7 and 12. Autistic-like traits were measured using the parent-reported Childhood Asperger Syndrome Test (CAST; Scott et al 2002) at both ages and internalizing traits were measured using the emotional subscale of the Strengths and Difficulties Questionnaire (SDQ; Goodman et al 1997). A genetically informative longitudinal cross-lagged model was used to determine the etiological factors affecting autistic-like and internalizing traits at both ages. It also enabled us to disentangle the genetic and environmental influences upon the longitudinal association between these traits. Importantly, this model estimated the direct influence of autistic-like traits at age 7 on internalizing traits at age 12 and vice versa.
Results: Both traits were moderately to highly heritable at both time points, although they were largely independent with respect to their genetic influences (genetic correlation <0.18). With regard to the longitudinal results, there were bidirectional processes involved in the relationship between autistic-like and internalising traits. Autistic-like traits at age 7 significantly contributed to the emergence of internalizing traits at age 12. There was also a smaller but significant influence of earlier internalizing traits upon the presence of later autistic-like traits. Both traits showed moderate stability across the 5 year period, although etiological influences were largely specific to each time-point. There was moderate stability in the genetic influences on autistic-like traits over time.
Conclusions: Our results suggest that early autistic-like traits have a direct influence upon the presence of internalizing traits later in childhood. Furthermore, the reverse association is also supported, although to a lesser extent. That is, the presence of autistic-like traits in later childhood is also associated with earlier levels of internalizing traits. These results have important implications for our conceptualisation of the relationship between internalizing and autistic-like traits. If these symptoms serve to mutually exacerbate each other, this could also influence the timing and effectiveness of intervention methods.
Objectives: The current study aimed to investigate the relationship between ‘autistic-like’ and internalizing traits within a population-representative sample in middle to late childhood. We assessed whether autistic-like traits had a direct influence upon later internalizing difficulties or vice versa and analysed the etiological factors influencing the longitudinal association between these traits.
Methods: Data was taken from the UK-based Twins Early Development Study (TEDS). Data for this study included approximately 5000 twin pairs assessed at ages 7 and 12. Autistic-like traits were measured using the parent-reported Childhood Asperger Syndrome Test (CAST; Scott et al 2002) at both ages and internalizing traits were measured using the emotional subscale of the Strengths and Difficulties Questionnaire (SDQ; Goodman et al 1997). A genetically informative longitudinal cross-lagged model was used to determine the etiological factors affecting autistic-like and internalizing traits at both ages. It also enabled us to disentangle the genetic and environmental influences upon the longitudinal association between these traits. Importantly, this model estimated the direct influence of autistic-like traits at age 7 on internalizing traits at age 12 and vice versa.
Results: Both traits were moderately to highly heritable at both time points, although they were largely independent with respect to their genetic influences (genetic correlation <0.18). With regard to the longitudinal results, there were bidirectional processes involved in the relationship between autistic-like and internalising traits. Autistic-like traits at age 7 significantly contributed to the emergence of internalizing traits at age 12. There was also a smaller but significant influence of earlier internalizing traits upon the presence of later autistic-like traits. Both traits showed moderate stability across the 5 year period, although etiological influences were largely specific to each time-point. There was moderate stability in the genetic influences on autistic-like traits over time.
Conclusions: Our results suggest that early autistic-like traits have a direct influence upon the presence of internalizing traits later in childhood. Furthermore, the reverse association is also supported, although to a lesser extent. That is, the presence of autistic-like traits in later childhood is also associated with earlier levels of internalizing traits. These results have important implications for our conceptualisation of the relationship between internalizing and autistic-like traits. If these symptoms serve to mutually exacerbate each other, this could also influence the timing and effectiveness of intervention methods.