Syndrome Specific and Non-Syndrome Specific Predictors of Developmental Change in Higher Functioning Children with Autism

Background: Within typically developing and clinical populations (e.g., ASD, ADHD), behavior problems tend to decrease as children transition into adolescence. Among higher functioning adolescents with autism (HFA), improvements are seen in standard scores of language and cognitive functioning (Sutera et al., 2007). Predictors of symptom improvement tend to be factors that correlate with initial severity including cognitive functioning, age of diagnosis, expressive language, and intervention history. However, non-syndrome specific factors, such as temperamental social withdrawal and effortful control, have yet to be explored in relation to developmental change.

 

Objectives: 1)To examine change in symptom severity and social/emotional functioning over time in a sample of HFA and an age- and IQ- matched sample of typically developing adolescents (COM). 2)To examine syndrome specific (i.e., IQ and initial symptomatology) and non-syndrome specific (i.e., Age, Effortful Control, and Surgency) factors as predictors of change.

 

Methods: Participants were 41 HFA and 42 COM adolescents, between the ages of 9 and 18. Parents completed the BASC-2, ASSQ, SCQ, EATQ, and SRS. Adolescents completed the self-report BASC-2 and WISC-IV. Composite T-scores of parent and adolescent rated internalizing and externalizing behaviors were computed. All measures were collected at two time points separated by 1.5 to 2.5 years.

 

Results : Controlling for age, IQ, and initial symptomatology, repeated measures ANCOVAs did not reveal developmental changes in ASD symptoms. However, an interaction between diagnostic group and time, F(1,78)=4.31, p=.04, η²=.05, revealed that the COM group showed a significant decline in internalizing problems, F(1,38)=4.57, p=.04, η²=.11, but the HFA group did not. Similarly, externalizing problems were predicted by a diagnostic group by time interaction, F(1,78)=6.08, p=.01, η²=.07, with a significant decline in externalizing behaviors in the HFA group, F(1,37)=6.81, p=.01, η²=.16, but not the COM group.

A series of regressions were conducted within the HFA group to analyze syndrome specific (IQ, symptom severity) and non-syndrome specific (age, Effortful Control, Surgency) predictors of change in symptoms and behavior problems. The model for symptom change was not significant. However, change in internalizing problems was significant, F(5,41)=3.81, p=.01, with greater Surgency predicting more improvement, t(35)=.2.5, p=.02. The model for change in externalizing was also significant, F(5,41)=3.36, p=.01, with older age, t(35)=2.35, p=.02, and higher IQ, t(35)=2.18, p=.04, predicting more improvement.

 

Conclusions: In summary, HFA participants did not show a decline in symptom severity and did not, as a group, show a reduction in internalizing problems like the COM sample did. However, within the HFA group, more approach oriented children showed a greater reduction in internalizing problems. Temperamental approach may allow children with HFA to benefit from the rich social learning environments of adolescence and function to reduce feelings of anxiety and depression. Interestingly, HFA participants showed more improvement in externalizing problems than COM participants and these improvements were most pronounced for older participants and those with higher verbal IQs. These factors may allow for improved socialization both at school and in the home. Results will be discussed in terms of risk and protective factors promoting behavior change over the transition to adolescence.