Age Related Differences of Executive Functions in Children and Adolescents in the Autism Spectrum

Background: There is a convincing amount of evidence of executive dysfunctions in children and adolescents with Autism Spectrum Disorders (ASD). However, given that patterns of individual profiles of executive functioning (EF) depend partly on age, it is important to take developmental perspective when studying EF in ASD. In everyday life, EF seems clearly deficient in people with ASD, even when adult level performances on EF laboratory tasks are reached. The behavior rating inventory of executive function (BRIEF: Gioia et al., 2000) is widely used in clinical practice to measure everyday EF, but the development of everyday EF in people with ASD has not yet received much attention.

Objectives: Exploring 1) age related patterns in everyday EF of children and adolescents with ASD; 2) the role of symptom severity in these age related patterns; 3) how many children with ASD actually have clinically relevant EF problems in daily life.

Methods: In a cross-sectional study of 116 children and adolescents (15 girls, 101 boys; age M = 13, SD = 2.8; age range 6-17) with ASD, four age groups (6-8, 9-11, 12-14, and 15 to 17 years) were compared on four BRIEF subscale scores (inhibition, working memory, shift, and planning).The Autism Diagnostic Observation Scale (ADOS: Lord et al., 2000) severity score was used as ASD symptom severity measure.

 Results: For two BRIEF subscales, inhibition, and planning there was a significant effect for age group. Compared to 6-8 year olds, 15-17 years old showed a decrease in inhibition problems, while the other posthoc group comparisons were not significant. Compared to 9-11 year olds, 12-14 year olds showed an increase of planning problems, but again the other comparisons were not significant. There were no significant correlations between symptom severity and the four subscales. Clinical scores of cognitive flexibility were observed in 52% of the sample, and in 44% for inhibition, 25 % for working memory, and 21% for planning. Hence, there are large individual differences in the deficits the children and adolescents with ASD encountered according to their parents.

Conclusions: Consistent with former studies, everyday EF deficits and individual differences were found in children and adolescents with ASD. Positive age development was seen for inhibition, while problems in planning increased with age. This might suggest that age effects for planning are due to changing demands from the school environment. This raises questions whether the BRIEF planning subscale is appropriate to provide information about EF development. Severity did not affect everyday EF. Cognitive flexibility seems to be the main problem area while planning was only affected in a relatively small proportion of the children and adolescents with ASD.