Autism Spectrum Disorder (ASD), is a complex lifelong neurodevelopmental disorder that typically appears within the first three years of life. It is considered to be a spectrum disorder meaning the primary symptoms can be expressed in varying degrees of severity.  Individuals with autism will have difficulties with verbal and non-verbal social communication, social interactions, and can display a range of rigid or stereotyped, repetitive behaviors, often with insistence on a specific routine that they will show resistance to changing.  Hyper- or hypo-sensitivity to sensory stimuli is also often observed. 

The diagnostic criteria for ASD was recently revised in May 2013 in the Fifth Edition of the Diagnostic and Statistical Manual (DSM-V) produced by the American Psychiatric Association (APA).  The edition immediately preceding it, the DSM-IV, had ASD or Autistic Disorder as one of five disorders under the umbrella of Pervasive Developmental Disorders (PDD):  Autistic Disorder, Asperger’s Disorder, Childhood Disintegrative Disorder (CDD), Rett’s Disorder, and Pervasive Development Disorder-Not Otherwise Specified (PDD-NOS).  Each of these disorders had specific diagnostic criteria but shared the primary symptoms of deficits in social communication, social interaction and rigid, stereotypical behaviors.



Exactly what causes ASD is still unknown. Current research suggests that a predisposition to autism might be inherited. Researchers have not found a specific “autism gene” but instead a nonspecific factor, which may increase the likelihood of having cognitive impairments.  Over the last five years, scientists have identified a number of rare gene changes, or mutations, associated with autism.  Researchers have also found neuro-biological differences in the brains of individuals with autism.  The current theory is that ASD is caused by a combination of “risk genes” and environmental factors in the early brain development period.