Autistic disorder. This is what most people think of when they hear the word "autism." It refers to problems with social interactions, communication, and imaginative play in children younger than 3 years.
Asperger's syndrome. These children don't have a problem with language — in fact, they tend to score in the average or above-average range on intelligence tests. But they have the same social problems and limited scope of interests as children with autistic disorder.
Pervasive developmental disorder or PDD — also known as atypical autism. This is a kind of catch-all category for children who have some autistic behaviors but who don't fit into other categories.
Rett syndrome. Children with Rett syndrome, primarily girls, start developing normally but then begin losing their communication and social skills. Beginning at the age of 1 to 4 years, repetitive hand movements replace purposeful use of the hands. Children with Rett syndrome are usually severely cognitively impaired.
Childhood disintegrative disorder. These children develop normally for at least two years and then lose some or most of their communication and social skills. This is an extremely rare disorder and its existence as a separate condition is a matter of debate among many mental health professionals.
These disorders may now be diagnosed as either a social communication disorder or autism spectrum disorder based on the primary impairments.
*These are individual disorders*
Pervasive Developmental Disorder, Not Otherwise Specified (PDD-NOS)
This mouthful of a diagnosis applies to most children with autistic spectrum disorder. Children whose autism is more severe than Asperger's syndrome but not as severe as autistic disorder are diagnosed with PDD-NOS.
Autism symptoms in kids with PDD-NOS vary widely, making it hard to generalize. Overall, compared to children with other autistic spectrum disorders, children with PDD-NOS have:
Impaired social interaction (like all children with autistic spectrum disorder)
Better language skills than kids with autistic disorder but not as good as those with Asperger's syndrome
Fewer repetitive behaviors than children with Asperger's syndrome or autistic disorder
A later age of onset
No two children with PDD-NOS are exactly alike in their symptoms. In fact, there are no agreed-upon criteria for diagnosing PDD-NOS. In effect, if a child seems autistic to professional evaluators but doesn't meet all the criteria for autistic disorder, he or she has PDD-NOS.
Autistic Disorder
Children who meet more rigid criteria for a diagnosis of autism have autistic disorder. They have more severe impairments involving social and language functioning as well as repetitive behaviors. Often, they also have mental retardation and seizures.
Rett Syndrome
Almost exclusively affecting girls, Rett syndrome is rare. About one in 10,000 to 15,000 girls develop this severe form of autism. Between 6 and 18 months of age, the child stops responding socially, wrings her hands habitually, and loses language skills. Coordination problems appear and can become severe. Head growth slows down significantly and by the age of two is far below normal.
Rett syndrome is usually caused by a genetic mutation. The mutation usually occurs randomly, rather than being inherited. Treatment focuses on physical therapy and speech therapy to improve function.
Childhood Disintegrative Disorder
The most severe autistic spectrum disorder, childhood disintegrative disorder (CDD), is also the least common.
After a period of normal development, usually between age 2 and 4, a child with CDD rapidly loses multiple areas of function. Social and language skills are lost as well as intellectual abilities. Often, the child develops a seizure disorder. Children with childhood disintegrative disorder are severely impaired and don't recover their lost function.
Fewer than two children per 100,000 with an autistic spectrum disorder meet criteria for childhood disintegrative disorder. Boys are affected by CDD more often than girls.
The American Academy of Pediatrics (AAP) recommends screening children for autism during regularly scheduled well-child visits.5 This policy helps doctors identify signs of autism early in its course. Early diagnosis and treatment can help the child reach his or her full potential.
