BABY SIBS STUDY
A Study of Infant Siblings of Children with Autism
Spectrum Disorders
A joint research project of The Children's Hospital
in Hamilton (Hamilton Health Sciences) and The
Hospital for Sick Children in Toronto and the IWK
Health Centre in Halifax
Principal Investigator: Lonnie Zwaigenbaum MD FRCPC;
Susan Bryson PhD
Co-Investigators: Peter Szatmari MD FRCPC; Isabel
Smith PhD; Wendy Roberts MD
We know that genetics
plays a role in autism. In 1977, Folstein and
Rutter published the first twin
study in autism and showed that the concordance
rate in identical twins was very much higher
than in non-identical twins.1 This finding has
now been
replicated several times and is well established.2
By following the development of infant siblings
of children already diagnosed with autism, we
are working to identify early behavioural markers
of
the condition so that interventions can be initiated
much earlier than is the case now.
Our infant
sibling study, which now includes over 100 families,
looks at the early development
of
siblings of children with autism/PDD. While most
siblings develop in an entirely typical fashion,
some siblings do show some differences in how
they communicate, interact and play, relative
to other
infants of the same age. We have developed a
new observational tool that has helped us to
elicit
and thoroughly document these atypical patterns
of development. This has helped us to identify
which infants require closer follow-up, and to
make suggestions to families on what may be helpful
for building their infants' skills.
Some of the
risk markers that we are investigating include
lack of social smiling, lack of response
to name calling, abnormal eye gaze and visual
tracking, decreased social responses, and sensory
overreactivity.
So far, we have found that approximately 25%
(1 in 4) of the infant siblings in our study
show
some indication of difficulty in early development
by the age of 12 months. We have also found that
the more early markers identified means the more
likely the child will show increased autistic
signs by the age of two. We are now developing
and evaluating
treatment strategies for children under the age
of 24 months who have been identified with early
signs of autism – interventions which may
ultimately prevent the full expression of this
severe disability.
This project is supported by the National
Alliance for Autism Research.
1Folstein S, Rutter M. Infantile autism: A
study of 21 twin pairs. J Child Psychol. Psychiatry
1977; 18:297-321
2Bailey A, LeCouteur A, Gottesman
I, Bolton P, Simonoff E, Yuzda E. Autism as a
strongly
genetic
disorder: Evidence from a British twin study.
Psychol. Med 1995;25:63-77
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