Autism is one of a group of neurodevelopmental disorders known as pervasive developmental disorders, which are characterized by impaired communication, impaired social interaction, and restricted, repetitive and stereotyped patterns of behaviors or interests. Autism spectrum disorders (ASDs) are used to describe three of the five pervasive developmental disorders, including autistic disorder, Asperger disorder, and a third category that includes pervasive developmental disorders that do not fit into the classic descriptions of developmental disorders.

Signs & Symptoms

Signs of these disorders usually become apparent in children by the time they are 3 years old. Autistic symptoms include a significant delay in language and cognitive development, while there is no significant language or cognitive development delay in Asperger syndrome. Because there are not significant language impairments in Asperger when compared to autism, Asperger syndrome may be referred to as "high functioning autism."
Symptoms can range from mild to severe. Some people may be considered autistic but function in society without issues, while for others, the condition can have a substantial impact on their lives and on the lives of those close to them.


Autism spectrum disorders are found across the world, seemingly regardless of race or cultural and economic background. ASD occurs more often in boys than in girls, with a 4:1 male:female ratio.
The U.S. Centers for Disease Control and Prevention (CDC) state that the numbers affected by autism are estimated to be around one out of every 110 children in the United States. However, various epidemiological studies have found varying rates of the condition, ranging from between one out of 80 children to one out of 240 children.
There are indications that instances of ASD are on the rise, but experts debate whether it is an actual increase or rather a case of more frequent diagnosis.

Types of Autism Spectrum Disorders

As its name infers, ASD refers to a range of symptoms.
ASDs were first defined as disorders in the 1940s by two different researchers working independently of each other. Dr. Leo Kanner studied what would come to be defined as severe or classic autism. At the same time, Dr. Hans Asperger defined the condition that now bears his name.
Classic autism usually entails substantial problems in all of the areas affected by ASDS, while someone with Asperger usually has issues with behavior and social interaction but often does not have problems with developing language. The symptoms experienced by people with Asperger are often also less severe.
There is debate as to whether Asperger Syndrome is a variation of classic autism (high-functioning autism) rather than a separate disorder.
PDD-NOS is a classification given when someone is exhibiting signs of autism but does not otherwise fit into the categories of classic autism or Asperger Syndrome.

Causes, Treatments & Outlook

The exact cause of autism and other autistic spectrum disorders is unknown. The most current science demonstrates that there is not a single cause for autism but that the disease is multi-factorial with a strong genetic component.
There is no cure for ASDs. The most effective treatments involve the use of early intensive behavioral interventions to improve the function of the child. It is generally agreed that the earlier a child is enrolled in these programs, the better their outlook.