Definition
Autism is a complex developmental disorder that appears in the first 3 years of life, although it is sometimes diagnosed much later. It affects the brain's normal development of social and communication skills.
Common features of autism include impaired social interactions, impaired verbal and nonverbal communication, problems processing information from the senses, and restricted and repetitive patterns of behavior.
The symptoms may vary from moderate to severe. Two related, milder conditions are Asperger syndrome and "pervasive development disorder not otherwise specified" (PDD-NOS).
Alternative Names
Pervasive developmental disorder - autism
Causes, incidence, and risk factors
Autism is a physical condition linked to abnormal biology and chemistry in the brain. The exact causes of these abnormalities remain unknown, but this is a very active area of research. There are probably a combination of factors that lead to autism.
Genetic factors seem to be important. For example, identical twins are much more likely than fraternal twins or siblings to both have autism. Similarly, language abnormalities are more common in relatives of autistic children. Chromosomal abnormalities and other neurological problems are also more common in families with autism.
A number of other possible causes have been suspected, but not proven. They involve digestive tract changes, diet, mercury poisoning, vaccine sensitivity, and the body's inefficient use of vitamins and minerals.
The exact number of children with autism is not known. A report released by the U.S. Centers for Disease Control and Prevention (CDC) suggests that autism and related disorders are more common than previously thought, although it is unclear if this is due to an increasing rate of the illness or an increased ability to diagnose the illness.
Autism affects boys 3 to 4 times more often than girls. Family income, education, and lifestyle do not seem to affect the risk of autism.
Some parents have heard that the MMR vaccine that children receive may cause autism. This theory was based, in part, on two facts. First, the incidence of autism has increased steadily since around the same time the MMR vaccine was introduced. Second, children with the regressive form of autism (a type of autism that develops after a period of normal development) tend to start to show symptoms around the time the MMR vaccine is given. This is likely a coincidence due to the age of children at the time they receive this vaccine.
Several major studies have found NO connection between the vaccine and autism, however. The American Academy of Pediatrics and the Center for Disease Control and Prevention report that there is no proven link between autism and the MMR vaccine.
Some doctors attribute the increased incidence in autism to newer definitions of autism. The term "autism" now includes a wider spectrum of children. For example, a child who is diagnosed with high-functioning autism today may have been thought to simply be odd or strange 30 years ago.
Symptoms
Most parents of autistic children suspect that something is wrong by the time the child is 18 months old and seek help by the time the child is 2. Children with autism typically have difficulties in verbal and nonverbal communication, social interactions, and pretend play. In some, aggression -- toward others or self -- may be present.
Some children with autism appear normal before age 1 or 2 and then suddenly "regress" and lose language or social skills they had previously gained. This is called the regressive type of autism.
People with autism may perform repeated body movements, show unusual attachments to objects or have unusual distress when routines are changed. Individuals may also experience sensitivities in the senses of sight, hearing, touch, smell, or taste. Such children, for example, will refuse to wear "itchy" clothes and become unduly distressed if forced because of the sensitivity of their skin. Some combination of the following areas may be affected in varying degrees.
Communication:
- Lack of pointing to direct others' attention to objects (occurs in the first 14 months of life)
- Does not adjust gaze to look at objects that others are looking at
- Cannot start or sustain a social conversation
- Develops language slowly or not at all
- Repeats words or memorized passages, such as commercials
- Does not refer to self correctly (for example, says "you want water" when the child means "I want water")
- Uses nonsense rhyming
- Communicates with gestures instead of words
Social interaction:
- Shows a lack of empathy
- Does not make friends
- Is withdrawn
- Prefers to spend time alone, rather than with others
- May not respond to eye contact or smiles
- May actually avoid eye contact
- May treat others as if they are objects
- Does not play interactive games
Response to sensory information:
- Has heightened or low senses of sight, hearing, touch, smell, or taste
- Seems to have a heightened or low response to pain
- May withdraw from physical contact because it is overstimulating or overwhelming
- Does not startle at loud noises
- May find normal noises painful and hold hands over ears
- Rubs surfaces, mouths or licks objects
Play:
- Shows little pretend or imaginative play
- Doesn't imitate the actions of others
- Prefers solitary or ritualistic play
Behaviors:
- Has a short attention span
- Uses repetitive body movements
- Shows a strong need for sameness
- "Acts up" with intense tantrums
- Has very narrow interests
- Demonstrates perseveration (gets stuck on a single topic or task)
- Shows aggression to others or self
- Is overactive or very passive
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