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Autistic traits in the general population: a twin study
John N Constantino1, Richard D Todd
1Department of Psychiatry, Washington University School of Medicine, St Louis, Mo 63110, USA. constantino@psychiatry.wustl.edu
Archives of General Psychiatry
|May 14, 2003
Summary
Autistic traits are common and heritable in the general population, with similar genetic influences in boys and girls. Females may be protected from developing more severe autistic traits due to environmental factors.
Area of Science:
- Psychiatry
- Genetics
- Developmental Psychology
Background:
- Autism spectrum disorder (ASD) is increasingly recognized as a spectrum, not a discrete condition.
- Family members of individuals with ASD often exhibit autistic traits of varying severity.
- These traits can exist below the diagnostic threshold for ASD.
Purpose of the Study:
- To investigate the prevalence and genetic underpinnings of autistic traits in the general population.
- To utilize the Social Responsiveness Scale (SRS) as a quantitative measure of autistic traits.
Main Methods:
- A sample of 788 twin pairs (ages 7-15) from the Missouri Twin Study was analyzed.
- Parents completed the Social Responsiveness Scale (SRS) for each child.
- Structural equation modeling was employed to analyze the data.
Main Results:
- Autistic traits demonstrated a continuous distribution and were moderately to highly heritable.
- Traits at or above the mean for patients with pervasive developmental disorder not otherwise specified were present in 1.4% of boys and 0.3% of girls.
- No sex-specific genetic influences were found; females may possess protective mechanisms against autistic traits.
Conclusions:
- Social deficits characteristic of ASD are prevalent in the general population.
- The continuous distribution of autistic traits suggests arbitrary cutoffs for diagnostic classification.
- Shared genetic influences for autistic traits exist in both sexes, with potential environmental factors contributing to lower prevalence/severity in females.