There are three main types of autism spectrum disorder, two types are quite rare.
The autism spectrum, also called autism spectrum disorders (ASD) or autism spectrum conditions (ASC), with the word autistic sometimes replacing autism, is a spectrum of psychological conditions characterized by widespread abnormalities of social interactions and communication, as well as severely restricted interests and highly repetitive behavior.
Autism spectrum disorders affect three different areas of a child's life:
Problems and difficulties with social interaction, such as a lack of understanding and awareness of other people's emotions and feelings.
Impaired language and communication skills, such as delayed language development and an inability to start conversations or take part in them properly.
Unusual patterns of thought and physical behavior. This includes making repetitive physical movements, such as hand tapping or twisting. The child develops set routines of behavior, which can upset the child if the routines are broken.
People with autism have difficulties with communication and social interaction and display restricted repetitive patterns of interest and activity. Autism is thought to be present soon after birth, with the characteristics of the disorder becoming apparent in the first three years of life.
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.
Around 75% of people with autism also have intellectual disability. The remaining 25% may have impaired insight, social functioning and communication skills but do not have intellectual disability or significantly reduced cognitive ability. This is called 'higher functioning autism'. A small number of people with higher functioning autism may have extraordinary creative or artistic skills and abilities. Asperger syndrome
This 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:
People with Asperger syndrome have social deficits and restricted patterns of interest and activity similar to people with autism. However, they do not have intellectual disability and the development of their language and cognitive skills appears to be normal, at least in the first two years of life. Professional and practical experience indicates clearly, however, that people with Asperger syndrome have disordered language and specific learning difficulties.
Formal recognition and diagnosis of Asperger syndrome usually occurs later than for autism. It is thought that it is probably because the person's social deficits don't become apparent until they spend time in social settings, such as kindergarten or school.
Signs of Rett syndrome that are similar to autism. Rett Syndrome is a childhood neuro-developmental disorder characterized by normal early development followed by loss of purposeful use of the hands, distinctive hand movements, slowed brain and head growth, gait abnormalities, seizures, and mental retardation. The signs of this disorder are most easily confused with those of Angelman syndrome, cerebral palsy and autism. It affects females almost exclusively. Rett syndrome is caused by mutations (structural alterations or defects) in the MECP2 (pronounced meck-pea-two) gene, which is found on the X chromosome.
Girls with Rett syndrome are prone to gastrointestinal disorders and up to 80% have seizures. They typically have no verbal skills, and about 50% of females are not ambulatory. Scoliosis, growth failure, and constipation are very common and can be problematic.
Rett Syndrome signs may stabilize for many decades, particularly for interaction and cognitive function such as making choices. Anti-social behavior may change to highly social behavior. Motor functions may slow as rigidity and dystonia appear. Seizures may be problematic, with a wide range of severity. Scoliosis occurs in most, and may require corrective surgery. Those who remain ambulatory tend to have less progression of scoliosis.
No single treatment is best and treatment is typically tailored to the child's needs. Intensive, sustained special education programs and behavior therapy early in life can help children acquire self-care, social, and job skills. The main goals of treatment are to lessen associated deficits and family distress, and to increase quality of life and functional independence. Available approaches include applied behavior analysis (ABA), developmental models, structured teaching, speech and language therapy, social skills therapy, and occupational therapy. ABA therapy has a strong research base but it maybe limited by diagnostic severity and IQ.