Autism and the ASDs are complex disorders of development. Children with ASDs do not follow the typical patterns of child development. They often have language problems, difficulty with social interactions, unusual behaviors, and limited interests in play.

The terminology of the ASDs can be confusing, as the terms “autism,” “ASDs,” and “PDD” are often used interchangeably or to mean different things by different parents and professionals. Usually the terms “ASD” or “PDD” include autistic disorder (classic autism), Asperger's syndrome, and Pervasive Developmental Disorder Not Otherwise Specified (PDD-NOS or atypical autism).

Causes of ASDS

Scientists do not know what causes ASDs. There is a lot of evidence that indicates that genes, their functions, and their interactions play an important role in the development of ASDs. There is also evidence that indicates that environmental factors may also play a role in causing autism.

Many other causes of ASDs have been proposed, including vaccines and their preservatives. To date there is no conclusive scientific evidence that any part of a vaccine causes autism.