Different Types of Autism
There are five different types of autism, each with its own particular diagnostic symptoms. Some types of autism are more functional than others. Autism always involves severe social interaction difficulties and usually includes behavior that is highly repetitive and ritualistic.
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Types
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Five types of autism include childhood autism, Asperger's syndrome, childhood disintegrative disorder, Rett syndrome and pervasive developmental disorder not otherwise specified (PDDNOS). These are not ordered on a scale of disability, but each has its own unique diagnostic features.
Theories/Speculation
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Researchers have not determined exactly what causes autism, although several theories prevail about the different types. Most evidence points to brain abnormalities or genetic factors, even if no other family members show signs of autism. Many families do show a pattern of autism or similar disabilities. Autism appears to affect all races and ethnic groups and all income and educational levels, in about the same percentage.
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Time Frame
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Childhood autism symptoms always appear before the child is three years old, and he will show severe impairment in communication and social interaction. Many will not display any speech skills at all. They typically show repetitive or obsessive behavior. About one in 5,000 children develop this form of autism, and boys have it three to four times more than girls. About 75 percent of cases occur in children who are mentally handicapped in other ways as well.
Identification
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Most children with Asperger's syndrome have fewer difficulties than those with childhood autism. They have problems with social interaction and typically exhibit repetitive and restrictive behavior. Sometimes they become intensely focused on one area of interest to the exclusion of almost everything else. They may do very well academically and have very impressive memories, yet may be unable to take care of themselves. This syndrome affects boys six to eight times more than girls, and studies vary in determinations of how many people are affected; estimates range from about one in 1,000 to five in 1,000.
Effects
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Children with CDD exhibit normal development for the first three or four years, then rapidly regress into severe disability. They may lose all the language skills they had developed and reject social interaction. Often they show repetitive behavior such as head bobbing. This is a relatively rare syndrome and affects only about one in 100,000 children. Again, more boys are affected than girls, with the disorder appearing about four times more often in boys.
Size
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Rett syndrome mainly affects girls, and boys very rarely. The child will develop normally for six months and then severely regress. The disease is associated with microcephaly, or an abnormally small head. The head stops growing after about six months to a year. The syndrome is often misdiagnosed as cerebral palsy. Teeth grinding and hand wringing are common definitive signs, and the children often develop other conditions, such as seizures. Estimates of how often the disease occurs vary from one in 10,000 to one in 23,000.
Features
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PDD NOS children have a lower degree of impairment and do not fit into any of the other four categories. They have severe difficulties with social interaction or communication, and typically show the repetitive ritualistic behavior associated with Asperger's.
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