Some of the different types of autism

• 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 catchall category for children who have some autistic problems but who don't fit into other categories.
• Rett's disorder - Known to occur only in girls, Rett's children begin to develop normally. Then they 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.