About AutismEMS
ASD/Autism Info
What are ASD?
The Spectrum
Autistic Meltdown
Course Materials

What are Autism Spectrum Disorders?

ASD TriangleAutism spectrum disorder (ASD) is a grouping Autism spectrum disorder (ASD) is a grouping of three closely-related developmental disabilities that are neurobiological in origin and are characterized by impaired social function, impaired communication and restrictive, repetitive interests, activities and behaviors (Jones et al, 2006).  The three disorders that comprise ASD are Asperger’s Syndrome (AS), Pervasive Developmental Disorder-Not Otherwise Specified (PDD-NOS) and Autistic Disorder (AD), sometimes referred to as “classic autism” (Johnson et al, 2007).   The generic term “autism” can be used to describe any of the autism spectrum disorders.

By definition, ASD is manifest by age 3, but often diagnosis is not made until several years later, with some people not being diagnosed until adulthood.  Diagnosis is based on the patient meeting a specific set of behavior characteristics and frequently occurs after other possible conditions have been excluded.  The criterion is defined in the current Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) and can be found at http://www.cdc.gov/ncbddd/autism/hcp-dsm.html.* 

Behavioral examples include:


Impaired Communication
Restrictive, Repetitive,
Behaviors, Interests
and Activities
Poor Eye Contact  

Poor use of facial

Selfishness/not sharing

Lack of interest in
   socializing with peers

Isolation / Resisting
   inclusion in group

Inability to recognize
   effect of their behavior 
   on others
Delay or absence of speech

Inability to perceive humor,
   sarcasm, idolism
   (takes everything seriously)

Inability to begin/sustain 

Inability to interpret other’s
    non-verbal communications
    (gesturing/facial expressions)

Lack of non-verbal communication 
    (pointing, etc)
Stereotyped motor mannerisms 

Rigid, inflexible adherence 
     to nonfunctional routines
     and rituals

Excessive preoccupation
      towards specific

The most current data indicates that approximately 1 in 91 children (age 3-17 years old) in the US are affected by the condition (Kogan et al, 2009) and the Autism Society of America (2008) estimates that 1.5 million American have a diagnosis on the spectrum.  It affects males about 4 times more often than females.  There are no significant differences in social-economic classes or nationality of those affected.  However, ASDs affect white, non-Hispanic persons more than the black or Hispanic populations.  The reason for this is not yet well understood and the prevalence between races is small (Centers for Disease Control, 2007).   

The cause of ASD is not well understood. A genetic connection has been demonstrated, although specific genes have yet to be identified and the heredity model is very complex. (Newschaffer, et al, 2007).  The only known risk factors are heredity (children with a sibling with an ASD are more likely to have an ASD) and chromosomal anomalies (children with certain genetic conditions are more likely to be diagnosed with an ASD).  

Environmental factors were once thought to be responsible for autism, although data does not support this link.  There is interest, however, of a genetic predisposition combined with an environmental “trigger,” causing the onset of symptoms (Lawler, et al, 2004). Vaccinations have also historically been blamed for causing ASD and there are many persons today still promoting this theory.  However, multiple recent studies, including Fombonne, et al (2001), the Institute of Medicine (2004) and others have concluded quite clearly that vaccinations do not cause autism spectrum disorders.  There are other factors that have been falsely accused of causing autism, such as stress, early life trauma, traumatic exposures (Autism Society of America, 2008) or “bad” parents or poor parental styles.  It is important to remember that none of these are true; in fact, parents now play a key role in effective treatment and support of the persons affected by autism (Myers et al, 2003).