Here's a look at the different types of autism spectrum disorders:
Autistic Disorder- This is what people commonly think of when they hear the term "autism." This diagnosis refers to problems with communication, social interaction and imaginative play in kids younger than three. It's usually diagnosed during a child's toddler years and symptoms can range from mild to severe.
Asperger's Syndrome- People with this type tend to have excellent language skills and average or above-average intelligence and do well on standardized tests. However, they lack social skills and aren't able to interact with their peers in a usual manner. It's a mild form of autism and children are able to do well in school, but have troubles with classmates due to the diagnosed child's awkward, sometimes odd, behaviors. Sometimes people aren't diagnosed with Asperger's until they're teens or adults. With specialized training, these people can lead typical lives and be active members of society.
Pervasive Developmental Disorder (PDD)- Also called atypical autism, this type is a miscellaneous category for people who don't clearly fit into one of the other, more defined, categories. People who fit this category have one or more traits of a few autistic categories but don't meet the criteria for any one diagnosis.
Rett Syndrome- This is found only in girls, but quite rare. Children with this type of autism develop normally for several years, and then their communication skills and social skills begin to regress. Between the ages of 1 and 4, they discontinue using their hands purposefully, and begin to make repetitive hand movements instead.
Childhood Disintegrative Disorder (CDD)- This is a rare type of autism. Children with this disorder develop normally for the first two years of life and then start to lose most of their motor, language, social, communication and potty skills.
Autism tends to run in families, and is found in people of all nationalities, races and socioeconomic levels. Researchers believe that certain types of genes predispose a child to the disorder. It's very rare that the disorder can be diagnosed at birth, but one is typically made before the child enters school.