Autistic 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 autistic spectrum disorder (ASD).

Autistic spectrum disorders seem to be on the rise. The NHS estimates ASD affects about one out of every 100 people in the UK. It's unclear, though, whether the growing incidence represents a real increase or just improved detection.

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

Signs of autistic spectrum disorder (ASD)

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

• Social interaction
• Communication (nonverbal and/or verbal)
• Repetitive behaviours or interests

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

Parents are usually the first to notice something is wrong. However, the diagnosis of ASD is often delayed. The parents or doctor often downplay early signs of autism. They may optimistically suggest "it's just a phase" or a trivial delay in development. Children with suspected ASD 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 syndrome
• Pervasive developmental disorder, not otherwise specified (PDD-NOS)
• Autistic disorder
• Rett syndrome
• Childhood disintegrative disorder

Asperger syndrome

The mildest form of autism, Asperger syndrome affects boys three times more often than girls. Children with Asperger 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 syndrome is mild compared to other autism spectrum disorders, some doctors call it "high-functioning autism". As children with Asperger’s syndrome enter young adulthood, though, they are at high risk of anxiety and depression.

Pervasive developmental disorder, not otherwise specified (PDD-NOS)

Pervasive Developmental Disorder – Not Otherwise Specified (PDD-NOS) is an autistic spectrum disorder. Children diagnosed with this condition share some traits of autistic disorder or Asperger syndrome.

Most children with PDD-NOS have milder symptoms than children with autistic disorder, but they do not share the language skills and above-average intelligence associated with Asperger syndrome.

Autistic disorder

Children who meet more rigid criteria for diagnosis of autism have autistic disorder. They have more severe impairments involving social and language functioning, as well as repetitive behaviours. Often, they have learning difficulties and seizures as well.

There are two rare, severe forms of autistic spectrum disorder that are considered separately from the others: Rett syndrome and childhood disintegrative disorder.