Types of Autism

Many people with autism are mentally challenged. In contrast to mental retardation alone, which is characterized by relatively even skill development, people with autism show uneven skill development. They may have problems in certain areas, especially the ability to communicate and relate to others. But they may have unusually developed skills in other areas, such as drawing, creating music, solving math problems, or memorizing facts. For this reason, they may test higher -- perhaps even in the average or above-average range -- on nonverbal intelligence tests.

Some of the different types of autism spectrum disorders include:

• 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. Known to occur mainly in girls, children with Rett syndrome start developing normally but begin to lose their communication and social skills. Beginning at the age of 1 to 4 years, repetitive hand movements replace purposeful use of the hands.
• Childhood disintegrative disorder. These children develop normally for at least two years and then lose some or most of their communication and social skills.

 Family income, lifestyle, or educational levels do not affect a child's chance of being autistic.