A report by the French Health Authority (Haute Autorité de la santé) says one child in 150 has a pervasive development disorder.
In 2009, it was estimated that there were 7 cases of pervasive development disorder (PDD) per 1,000 people under 20 years of age. There are two cases of autism per 1000. Autism is one category of pervasive developmental disorders. Other PDDs include Asperger’s Syndrome (AS) and Rett’s disorder (RD), Childhood Disintegrative Disorder (CDD) and Pervasive Developmental Disorder – Not Otherwise Specified (PDD-NOS).
The Autism Society of Canada explains that "Individuals with ASDs (Austistic Spectrum Disorders) have varying degrees of difficulty in social interaction and communication and may show repetitive behaviours and have unusual attachments to objects or routines."
The society’s website goes on to say that "Autism is the most common neurological disorder affecting children and one of the most common developmental disabilities affecting Canadians in general. ASDs change the way the brain processes information and can affect all aspects of a person’s development. Classic autism usually appears during the first three years of life. Autism is four times more common in boys than girls."