Correlations between temperament and autistic trait measures – Quantitative or qualitative differences between children with and without autism spectrum disorders?

Background The study tested the spectrum hypothesis, which claims that children with Autism Spectrum Disorder with normal intelligence differ in terms of temperament from typically developing peers quantitatively and not qualitatively. Severity of autistic traits was also taken into account and the question whether temperament may serve as predictor for autistic traits was tested. Methods Participants included 352 children, aged 4–11 years, from the general population and 79 children with an ASD diagnosis. Parents completed questionnaires about the severity of autistic traits and temperament of their children. Results Quantitatively, differences in means were found between ASD and non-clinical groups in terms of emotionality, sociability, activity and shyness. Qualitatively, in the ASD group, there was higher variance in autistic traits, as well as sociability, activity, and shyness. There were also differences between ASD and non-clinical groups in internal consistency with respect to autistic traits and shyness but not activity, sociability and emotionality. In addition, the relationship between shyness and autistic traits was stronger in the ASD group than in the non-clinical group. Conclusions The results do not definitively confirm the spectrum hypothesis but further research is needed with better control for the severity of ASD symptoms in study groups and more sophisticated statistical analysis methods.