Autism Spectrum Disorders

The forms of autism are thought to overlap considerably. But the fact that there is wide variation in symptoms among children with autism led to the concept of autism spectrum disorder.

Autism seems to be on the rise, and autism spectrum disorders affect between two and six children out of every 1,000 in the U.S. It's unclear, though, whether the growing incidence of autism represents a real increase or just improved detection.

Early diagnosis of an autism spectrum disorder is important. That's because detection leads to treatment, and with early treatment, a child with autism can gain improved language and social skills.

Signs of Autism Spectrum Disorder

Autism spectrum disorders affect three different areas of a child's life:

• social interaction
• communication (nonverbal and/or verbal)
• repetitive behaviors or interests

Each child with an autism spectrum disorder will have his or her own individual pattern of autism. Sometimes, a child's development is delayed from birth. Other children with autism develop normally before suddenly losing social or language skills. In some children, a loss of language is the impairment. In others, unusual behaviors (like spending hours lining up toys) predominate.

Parents are usually the first to notice something is wrong. However, the diagnosis of autism is often delayed. The parents or a physician often downplay early signs of autism. They may optimistically suggest "it's just a phase" or a trivial delay in development. Children with a suspected autism spectrum disorder should be evaluated by a professional team with experience in diagnosing autism.

There are three main forms of autism spectrum disorder, and two rare, severe autistic-like conditions:

• Asperger's syndrome
• pervasive developmental disorder, not otherwise specified (PDD-NOS)
• autistic disorder
• Rett syndrome
• childhood disintegrative disorder

Asperger's Syndrome

The mildest form of autism, Asperger's syndrome affects boys three times more often than girls. Children with Asperger's syndrome become obsessively interested in a single object or topic. They often learn all about their preferred subject, and discuss it nonstop. Their social skills are markedly impaired, though. They are often awkward and uncoordinated physically.

Because Asperger's syndrome is mild compared to other autism spectrum disorders, some doctors call it "high-functioning autism." As children with Asperger syndrome enter young adulthood, though, they are at high risk for anxiety and depression.

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:

• impairment in 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

However, 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.