Autism         Autism is one of the mental, emotional, and behavior disorders that appears in early childhood. Autism, or autistic disorder, almost always develops within the first 3 years of a child's life. Children and adolescents with autism cannot interact normally with other people. Autism thus affects many aspects of their development.         Children with and adolescents with autism typically: -have a difficult time communicating with others -exhibit very repetitious behaviors (like rocking back and forth, head banging, …showed first 75 words of 315 total…

…showed last 75 words of 315 total…the immune system, or genetics.         Scientists also have identified chemicals in the brain and the immune system that may be involved in autistic disorder. As a normal brain develops, the level of serotonin, a chemical found in the brain, declines. In some children with autistic disorder, however, the serotonin levels do not decline. Now researchers are trying to determine whether this happens only to children with autism and why, and whether other factors are involved.