Autism is a complex developmental disability that typically appears during the first three years of life and is the result of a neurological disorder that affects the normal functioning of the brain, impacting development in the areas of social interaction and communication skills. Both children and adults with autism typically show difficulties in verbal and non-verbal communication, social interactions, and leisure or play activities. One should keep in mind however, that autism is a spectrum disorder and it affects each individual differently and at varying degrees - this is why early diagnosis is so crucial. By learning the signs, a child can begin benefiting from one of the many specialized intervention programs.

Autism is one of five disorders that falls under the umbrella of Pervasive Developmental Disorders (PDD), a category of neurological disorders characterized by “severe and pervasive impairment in several areas of development.”

The five disorders under PDD are:

• Autism
• Asperger's Disorder
• Childhood Disintegrative Disorder (CDD)
• Rett's Disorder
• PDD-Not Otherwise Specified (PDD-NOS)

Each of these disorders has specific diagnostic criteria which been outlined in the American Psychiatric Association's Diagnostic & Statistical Manual of Mental Disorders (DSM-IV-TR).

Autism is the most common of the Pervasive Developmental Disorders, affecting an estimated 1 in 150 births (Centers for Disease Control Prevention, 2007). As many as 1.5 million Americans today are believed to have some form of autism. Based on statistics from the U.S. Department of Education, autism is growing at a startling rate of 10-17 percent per year. At this rate, the prevalence of autism could reach 4 million Americans in the next decade. Autism is four times more prevalent in boys than in girls.