How Does Temperamental Individuality Impact the Developmental Course of Symptoms and Maladjustment in Youth with Autism Spectrum Disorder? a 9-Year Longitudinal Study

Background:

Scholars increasingly suggest that the study of unique behavioural traits, as captured by temperament and personality models, may provide valuable keys to better grasp the wide behavioural variability demonstrated by individuals with autism spectrum disorders (ASD). Multiple cross-sectional studies have now identified salient temperament or personality differences associated with the autism spectrum condition, in adulthood but also in childhood and adolescence. Surprisingly little research, however, has addressed the longitudinal impact of these temperamental variables on developmental outcomes. Two important research questions, particularly salient in childhood and adolescence, relate to the impact of this behavioural uniqueness (ideally comprehensively assessed using temperament as well as personality constructs) on the developmental course of autism symptoms on the one hand, and on the course of psychosocial problems on the other.

Objectives:

This study evaluates the dynamic interplay between unique child characteristics, as measured by temperament and personality, the course of autism-related symptoms, and the manifestation of psychosocial problems, in a 9-year longitudinal study of children and adolescents with autism. First, this study addresses stability and change in temperament/personality, dimensional ASD-symptoms, and internalizing/externalizing problems. Second, the study evaluates the impact of temperament and personality traits on the developmental course of symptoms and of psychosocial problems.

Methods:

Parents of 139 children with ASD reported on their perceptions of the child’s temperament (Early Adolescent Temperament Questionnaire-Revised), personality (Hierarchical Personality Inventory for Children), dimensional autism symptoms (Social Responsiveness Scale) and psychosocial problems (Child Behavior Checklist) at three occasions. At Time 1 (T1), children were on average 10.2 years old (SD = 2.4). At Time 2 (T2), the mean age was 16.0 years and at Time 3 (T3), the mean age was 19.0 years.

Results:

Correlational and repeated measurement analyses indicate that all variables (temperament, personality, ASD-symptoms, and behavioural problems) demonstrate substantially high continuity across the nine-year interval. Nevertheless, some marked, yet limited, developmental changes can be noted: temperament and personality profiles tend to become slightly more adaptive and both ASD-symptoms and psychosocial problems linearly decrease across the measurement waves. Notably, we found that the impact of child temperament/personality on the course of SRS-symptoms was more modest than expected: higher scores on ASD-symptoms were moderately associated with higher temperamental Negative Affect and lower Effortful Control, and lower Benevolence in personality, both within- and across-time. By contrast, child temperament/personality had major, predictive validity for the presence as well as the developmental course of psychosocial problems. Externalizing problems were mainly predicted, both cross-sectionally and longitudinally, by perceived difficulties in temperamental Negative Affect, and in the personality traits Extraversion and Benevolence. Internalizing problems were mainly predicted by Negative Affect and lack of Emotional Stability in personality.

Conclusions:

This study documents that youth with ASD shows both substantial stability and change in the manifestation of temperament, personality, ASD-symptoms and psychosocial problems across childhood and adolescence. The relative impact of child temperament/personality on the developmental course of internalizing and externalizing problems appears to be much more pronounced than the impact of temperament/personality features on the developmental course of autism spectrum symptoms.