Autism prodrome 6 of 89
a younger sibling of a child diagnosed with ASD who is at genetically higher risk
compared to other children.
The aim of the current paper is to provide a state of the art summary regarding
the early signs, risk factors and prodrome of ASDs. We will examine common early
markers for ASDs first, as evidenced in retrospective and prospective studies of
samples children with ASDs as well as children who are at risk for ASDs, followed by
a review of the pre-, and peri-natal risk factors, and a section on genetics and ASD in
the context of risk markers and the prodrome and etiology of ASDs. We will
conclude with some ethical issues regarding early diagnosis and prevention/
intervention and some thoughts for future studies.
Our scientific ability to learn about the prodrome of ASDs is strongly
associated with the available technology and with the diagnostic criteria in existence.
When autism was a considerably rare behavioral disorder with a prevalence rate of 4-
5 cases per 10,000 live births (Lotter, 1966; see Fombonne, 2009, for a review) it was
impossible and not cost effective to conduct large screening studies. Such studies are
now much more feasible given that prevalence rates for the broadly defined autism
spectrum are now estimated to be between 1 in 100 to 1 in 150 (Baird et al., 2006;
CDC, 2007). Similarly, during the early years of the field we had to rely on parental
reports about early development knowing that the validity of these reports may not be
high due to factors such as selective memory and seeing things through the prism of
the disorder. With video recording becoming a common practice in many families in
western society, scientists were able to corroborate parental reports by collecting and
analyzing home video recordings of the children filmed prior to receiving an ASD
diagnosis. With the widening of the diagnostic criteria and the emergence of new