Understanding ASD: Autism Spectrum Disorder

What is Autism?

Autism is a severe and chronic developmental disorder that results in significant lifelong disability for most persons. Very few individuals afflicted with Autism ever live to achieve normal and independent functioning (Shapiro & Accardo, 2008). Autism generally refers to a spectrum of disorders rather than a single illness. It includes several pervasive developmental disorders (PDDs) such as Asperser’s disorder and Pervasive Developmental disorder, Not Otherwise specified (PDD-NOS), all characterized by significant impairments in social and communication skills and by stereotyped patterns of interests and behaviors. Individuals with autism vary widely in the form, pervasiveness, and severity of their symptoms and abilities. As such, individuals diagnosed with autism can be vastly different from one another (Mash & Wolfe, 2009).

from: http://www.healthofchildren.com/images/gech_0001_0001_0_img0029.jpg
from: http://www.healthofchildren.com/images/gech_0001_0001_0_img0029.jpg

Currently, the diagnostic criteria of ASD are commonly those listed in the Diagnostic and Statistical Manual (DSM) of the American Psychiatric Association. According to the DSM, a diagnosis of ASD requires the presence of qualitative impairments in three core areas: social interaction, communication, and behavioral impairments. The DSM states that “there are must be qualitative impairment in reciprocal social interaction, relative to developmental level” (Frith, 2003) for the diagnosis of ASD. Behavioral manifestations include poor use of eye gaze and hand gestures. The second diagnostic criterion requires the presence of qualitative impairment in verbal and nonverbal communication (such as eye contact, gaze and facial expression). Behavioral signs include absent or delayed speech development, inability to initiate or sustain conversation, stereotyped and repetitive language as well as a lack of developmentally appropriate imaginative play. The last diagnostic criterion requires the presence of behavioral impairment including restricted, repetitive, and stereotyped patterns of behavior, interests and activities. Self-injurious and aggressive behavior may be present, along with repeated body movements such as hand flapping or rocking. The DSM further stipulates that the triad of deficits must occur prior to age three for a diagnosis of ASD.

According to Autism Society Canada, the prevalence rate of ASD in the general Canadian population is approximately 1 in 200 (Autism Society Canada, 2009). The prevalence rate is slightly higher for school age children, with 1 in every 165 diagnosed with ASD. These figures are consistent with those reported in United States and United Kingdom, where rates of around 0.6% (or 1 in 167) have been found (2009). Interestingly, ASD is about three to four times more common in boys than girls (Koenig & Tsatsanis, 2005). It also shows no particular ethnic or class difference in prevalence rate (2005). The long term prognosis for autism is very poor. In most cases, it results in lifelong disability. Early studies on adult outcomes of autistic children found that majority of autistic adults (70 percent or more) had poor outcomes with limited progress. Given the poor prognosis and lifelong cost of this disability, significant efforts are needed in finding an effective comprehensive treatment program for autism.


American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders (4th ed., text revision). Washington, DC: American Psychiatric Association.

Autism Society Canada. (2009). Prevalence. In Autism Society Canada.

Frith, U. (2003). Autism: explaining the enigima. Malden, MA: Blackwell Publishing.

Koenig, K., & Tsatsanis, K. D. (2005). Pervasive developmental disorder in girls. In D. J.Bell, S. L. Foster, & E. J. Mash (Eds.), Handbook of emotional and behavioral disorders in girls (pp. 211-237). New York: Kluwer.

Mash, E. J., & Wolfe, D. A. (2009). Abnormal Child Psychology: Fouth Edition. Belmont, CA: Wadsworth.

Shapiro, B. & Accardo, P. (2008). Autism Frontiers: Clinical Issues and Innovation. Chelsea, Michigan: Paul H. Brookes Publishing Co.

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