Association Between Intellectual Functioning and Autistic Traits in the General Population of Children.

Autistic traits are continuously distributed in the general population. The associations between autistic traits and intellectual functioning and/or behavioural difficulties, and the impact of intellectual functioning on behavioural difficulties are unclear. The study aims to describe the distribution of autistic traits in a population-based cross-sectional sample of children. Further aims are to examine the association between intellectual functioning and autistic traits, and between autistic traits and behavioural difficulties. Wechsler scales and ratings of autistic traits and behavioural problems in 874 children aged 7-9 years in the Swedish Environmental Longitudinal Mother and Child, Asthma and Allergy (SELMA) study were assessed. We found a continuous distribution of autistic traits. Intellectual functioning was negatively associated with autistic traits but not with behavioural difficulties. Behavioural difficulties were associated with autistic traits.