Recent research has focused on the prevalence rates of autistic symptomatology in the siblings of individuals with an autism spectrum disorder (ASD). This interest is related to the evidence linking genetic risk factors to the development of autism. It has led to the development of a body of literature supporting the existence of social and language deficits, although not severe, in siblings of individuals with autism.
Objectives:
This investigation used the NEPSY-II Social Perception scales – Theory of Mind and Affect Recognition – to investigate social deficits in children with an ASD and their siblings compared to an age- and gender-matched control group. The NEPSY-II has been shown to be both reliable and valid as an instrument and is one of the few established neuropsychological assessments to include a theory of mind subscale.
Methods:
Participants included children with autism, their siblings, and neurotypical controls between the ages of 3 and 12 years. Subjects were recruited to participate in a larger study examining the relationships between oxytocin biology and social deficits as measured by the NEPSY-II’s Theory of Mind and Affect Recognition tasks. Autism diagnosis was based on the Autism Diagnostic Observation Schedule (ADOS), Autism Diagnostic Interview Revised (ADI-R), and expert clinical opinion.
Results:
To date 105 participants (62 boys and 43 girls) have completed the study procedures including 28 children with an ASD, 29 siblings, and 48 controls. There were no significant age or gender differences between groups. As expected, children with an ASD performed significantly worse on both tasks compared to the control sample [Affect Recognition: F(1, 71) = 20.933, p = 0.000, Theory of Mind: F(1, 71) = 29.407, p = 0.000]. Interestingly, the siblings group performed better than the affected probands on both Theory of Mind [F(1, 52) = 15.830, p = 0.000] and Affect Recognition [F(1, 53) = 7.153, p = 0.010] tests, with no differences between siblings and controls. Additionally, no significant gender differences were observed, either overall or within groups.
Conclusions:
Findings from this preliminary investigation indicate that the siblings of children with an ASD have minimal deficits in theory of mind tasks and affect recognition, as measured by the NEPSY-II. Future studies with larger sample sizes are needed to further examine these observations, especially in light of the mounting evidence suggesting that siblings exhibit some levels of social deficits.