Autism is called a developmental disability because it appears before age 3, when a child is developing skills like walking and talking. Autism causes delays in how the child develops and grows. It strikes males about four times more often than females. It continues throughout life. People with autism have a normal life expectancy. It's estimated that two to six people in every 1,000 individuals has autism.

People with autism often don't respond to others' emotions. They may not realize how their behavior affects others. They have difficulty interpreting others' tone of voice or facial expressions. Children with autism often speak later than other children and have hearing problems. They may also rock, twirl their hair or bang their heads repetitively. People with autism also don't feel pain as vividly as others, and they may have an abnormal response to sounds or touch.

You should have your child evaluated for autism immediately if any of these symptoms are present. Other behaviors that should raise concerns include possible deafness, or deafness that comes and goes; the child used to speak but now does not; the child doesn't smile when smiled at; the child throws intense temper tantrums; and the child walks on his or her toes.

Asperger syndrome is one of five illnesses, including autism, that are called autism spectrum disorders (ASDs). The others are pervasive developmental disorder/not otherwise specified (PDD/NOS), when children have some symptoms of autism but not enough to be diagnosed with it; childhood disintegrative disorder (CDD), in which children appear normal for the first several years of life but then begin to develop autistic behavior; and Rett syndrome, a genetic disorder in girls marked by limited brain growth and seizures.

A number of genes appear to play a role in autism, as do environmental factors. Research has found brain abnormalities in people with autism. Neurons in the cerebellum, amygdala, hippocampus, septum and mamillary bodies of autistic people are smaller than normal and have stunted nerve fibers. These changes may mean that something interfered with brain development of the fetus. Other studies have found problems with the signaling molecules in the brain of those with autism. Recent research found a significant increase in autism cases in California, although experts can't explain why. Other disorders, including Tourette syndrome, learning disabilities and attention deficit disorder, often occur with autism but do not cause it. About a third of children with autism eventually develop epilepsy.

Although some parents believe that the measles/mumps/rubella vaccine caused their children's autism, no scientific proof has been found to back this up. The symptoms of autism often appear around the same time as the MMR vaccine is given. That doesn't mean, however, that the vaccine has caused the autism. There is no scientific proof that any vaccine or combination of vaccines causes autism.

Autism has no cure. Behavioral therapy and medication may help ease symptoms, however. In behavioral therapy, therapists work one-on-one with children to help them develop social and language skills. The earlier a child is helped with this therapy, the better the outcome. Medication may be prescribed to ease troublesome behavior or other symptoms of autism. The medication affects the levels of signaling chemicals such as serotonin in the brain.