An Overview of Autism and Possible Causes

For years, most people thought of autistic children as people who could barely talk, who banged their heads on the wall in a repetitive motion and who were extremely mentally retarded. Today, we’ve learned so much more. Perhaps the biggest change in our knowledge is that there is an extremely wide range of behavior that can be classified as autistic. So much so that many researchers now prefer to call it “autism spectrum disorder, (ASD)” because cases range from very mild to severe. There are some children with ASD who are very mentally retarded and need to go to special schools, but other ASD kids can go to regular schools (and get special education services), speak completely intelligibly, learn to read, etc. About 70 percent of kids with ASD are mentally retarded to some degree. But a small percentage of ASD children eventually seem to recover completely and go on to lead normal lives.

The hallmark of autism is that people who have it always experience some level of difficulty relating to other people, understanding the emotions and feelings of others and “reading” facial expressions. They are unable to pick up on the subtle clues that allow people to feel empathy for others and to act appropriately in society. They simply do not blend in easily in the world, so even if they’re not mentally retarded, they may not be able to hold down a job or live independently.

What do we know about the cause of autism?
Earlier, researchers thought that autism was caused by the way a child was raised. There even used to be a term—“refrigerator mothers”—that some researchers used to describe the parenting style of women who had autistic children. The theory was that children with autism had cold, distant mothers who withheld love and affection. Part of that may have stemmed from the fact that autistic children often have “flat” personalities, and they seem indifferent to cuddling or other affectionate behaviors.

Now, experts believe that autism is caused by an interplay of genetic and environmental factors. While nobody knows the cause, in the past decade researchers have identified several factors that they hope will eventually explain why autism occurs and that may provide new treatments. For example, children with autism have:

• Larger brains than normal children.
• Larger outer zones of white matter in proportion to the rest of the brain
• Larger gray matter and a larger cerebellum in proportion to the rest of the brain
• Smaller brain cerebral cortex and hippocampus
• Smaller stacks of neurons in the brain; these stacks are also greater in number and more uniform than in normal brains.

Additionally, children with autism generally focus on different points in a setting than people who don’t have autism. For example, if you show a scene from a movie in which several people are having a conversation, normal people would focus on watching the characters who are talking. But someone with autism may focus instead on something completely different, such as a doorknob.

Even though researchers have learned these things about the brains of people with autism, they still really don’t know why these abnormalities cause the condition. But the hope is that eventually, all of the clues will uncover the cause and lead to new, improved treatments.

In terms of causes, there is no evidence that vaccines are contributors, although some of the more radical autism groups continue to believe that vaccines may have something to do with the condition. There are also some researchers who believe that food allergies may play a role. Additionally, it seems that genetics are a factor. Parents who have one child with autism are at a 100 times increased risk of having another child with autism. And in twin studies, if one identical twin has autism, the other twin has a 60 to 85 percent chance of having it as well.

Source:
The National Institute of Mental Health; The New York Times, Science Times Section, “Lifting the Veils of Autism, One by One,” 24 February 2004;