Teaching Students with Autism Spectrum Disorders

Chapter One What Is Autism?
Bryson, S. E., et al., (1997) “Epidemiology
of Autism: Overview and issues
outstanding”, in Handbook of Autism
and Pervasive Developmental Disorders
(2 nd ed.).
Szatmari, P. , et al., (1998) “Genetics
of Autism: Overview and new directions”,
Journal of Autism and Developmental
Disorders, 28 (5), 351-368.
Rodier, P., (January, 2000) “The early
origins of Autism”, Scientific American.
(1999) Clinical Practice Guideline:
Report of the Recommendations
Autism/Pervasive Developmental
Disorders, Assessment and Intervention
for Young Children (ages 0-3
years)
Although people with ASD share some common features, no
two individuals are the same. The pattern and extent of difficulties
may change with development. Knowledge of the common
characteristics, combined with knowledge of the specific interests,
abilities, and personality of each individual, helps us to understand
general needs associated with ASD.
Prevalence of Autism Spectrum Disorders
The generally accepted prevalence rate for Autistic Disorder,
per se, has increased from 4-5/10,000 to 10-15 in every 10,000 births,
even as high as 20 in 10,000 births, when the broader Autism
Spectrum is included. It is estimated that one in 250 children in New
Brunswick are affected with Autism Spectrum Disorder. Prevalence
is higher among males. The ratio varies depending on the definition,
but studies reveal a male-to-female ratio of between 3:1 and 4:1.
Causes of Autism Spectrum Disorders
While the cause or combination of causes of ASD is not fully
known, there is growing evidence that ASD is a genetic condition,
and that several different genes are likely involved. The mode of
genetic transmission appears complex. Scientists are focusing their
work on finding which genes may be involved and how these genes
are affected. To date, it appears that for at least a significant subgroup
of persons with ASD, a genetic susceptibility exists which differs
across families (that is, different genes may be responsible in different
families). Fragile X syndrome is the most common specific genetic
disorder that is sometimes associated with the clinical picture of
autism.
Evidence suggests that there may be a higher prevalence of
problems very early in the mother’s pregnancy, at birth, or even after
birth among children with ASD than among children who do not
have ASD. Early life events and environmental factors may interact
significantly with genetic susceptibility in the child.
Recently, various types of investigations, including imaging
studies, electro-encephalographic studies, tissue studies on autopsy
materials, and neuro-chemical studies, have provided further evidence
of a biological basis for ASD. The brains of individuals with ASD
appear to have some structural and functional differences from the
brains of other people. Abnormalities have been found in the brain
stem and cranial nerves.
A controversial argument of a causal relationship between
childhood immunizations and ASD persists. Currently, no definitive
empirical evidence of a relationship exists. Ongoing research may
4 Teaching Students with Autism Spectrum Disorders