|
Autistic Traits in the
General Population
A Twin Study
John N. Constantino, MD;
Richard D. Todd, PhD, MD
Arch Gen Psychiatry. 2003;60:524-530.
Background Recent research has
indicated that autism is not a discrete
disorder and that family members of autistic
probands have an increased likelihood of exhibiting
autistic symptoms with a wide range of
severity, often below the threshold for a
diagnosis of an autism spectrum disorder.
Objective To examine the distribution and
genetic structure of autistic traits in the
general population using a newly established
quantitative measure of autistic traits, the Social
Responsiveness Scale (formerly known as the
Social Reciprocity Scale).
Methods The sample consisted of 788 pairs of
twins aged 7 to 15 years, randomly selected
from the pool of participants in a large
epidemiologic study (the Missouri Twin Study). One
parent of each pair of twins completed the Social
Responsiveness Scale on each child. The data
were subjected to structural equation
modeling.
Results Autistic traits as measured by the
Social Responsiveness Scale were continuously
distributed and moderately to highly
heritable. Levels of severity of autistic traits at or
above the previously published mean for
patients with pervasive developmental
disorder not otherwise specified were found in 1.4% of
boys and 0.3% of girls. Structural equation
modeling revealed no evidence for the
existence of sex-specific genetic influences,
and suggested specific mechanisms by which females may
be relatively protected from vulnerability to
autistic traits.
Conclusions These data indicate that the
social deficits characteristic of autism
spectrum disorders are common. Given the
continuous distribution of these traits, it may be
arbitrary where cutoffs are made between
research designations of being "affected" vs
"unaffected" with a pervasive developmental disorder.
The genes influencing autistic traits appear to be
the same for boys and girls. Lower prevalence
(and severity) of autistic traits in girls
may be the result of increased sensitivity to
early environmental influences that operate to promote
social competency.
From the Departments of Psychiatry (Drs
Constantino and Todd), Pediatrics (Dr Constantino), and
Genetics (Dr Todd), Washington University School of
Medicine, St Louis, Mo.
RELATED ARTICLES IN
ARCHIVES OF GENERAL PSYCHIATRY
This Month in Archives of General
Psychiatry
Arch Gen Psychiatry. 2003;60:441.
FULL TEXT
|
