The Facts About Autism

Researchers at the National Institute of Child Health and Human Development (NICHD), part of the National Institutes of Health (NIH), are trying to understand autism: what it is, what causes it, how to diagnose it, how to treat it. Autism is very complex. No two people with autism are exactly the same and no two people with autism respond to treatment in the same way. So research in autism is also very complex. Learn more about autism here.
What is autism?
Some people have compared solving the puzzle of autism to peeling an onion: new insights reveal themselves one layer at a time. Knowledge of autism is always changing, as research peels away more and more layers of this perplexing disease. This article explains what NICHD researchers who study autism have found out so far in their attempts to understand autism.

Autism is a complex biological disorder that generally lasts throughout a person's life. It is called a developmental disability because it starts before age three, in the developmental period, and causes delays or problems with many different ways in which a person develops or grows.

In most cases, autism causes problems with:

  • Communication, both verbal (spoken) and nonverbal (unspoken)
  • Social interactions with other people, both physical (such as hugging or holding) and verbal (such as having a conversation)
  • Routines or repetitive behaviors, like repeating words or actions over and over, obsessively following routines or schedules for their actions or having very specific ways of arranging their belongings

The symptoms of the disorder cut off people with autism from the world around them.Children with autism may not want their mothers to hold them. Adults with autism may not look others in the eye. Some people with autism never learn how to talk. These behaviors not only make life difficult for people who have autism, but also make life hard for their families, their health care providers, their teachers and anyone who comes in contact with them.

Why do some people get autism?
Autism is not a disease that you "get," the same way you can get the flu. Instead, scientists think autism has its beginnings before a person is even born. No one knows the exact cause or causes of autism, but scientists have some theories.

Some of the researchers in the Network on the Neurobiology and Genetics of Autism: Collaborative Programs of Excellence in Autism (CPEA), a worldwide research network co-sponsored by the NICHD and the National Institute on Deafness and Other Communication Disorders (NIDCD), are focusing their efforts on possible genetic causes of autism.

In 2000, scientists in the CPEA Network released the results of two studies that found genes were involved in autism. Additional papers were published in 2001 by CPEA researchers and other NIH-funded scientists as part of an international consortium on genetics research. These results lead researchers to believe that some people could have an error in their genes that makes them more likely to develop autism. The CPEA Network and other NICHD-supported researchers are also looking into other factors that could be involved in autism, in addition to genetics, including neurological, infectious, metabolic, immunologic and environmental.

How many people have autism?
Currently, the exact number of cases of autism is not known, but estimates range from one-in-500 cases, to one-in-1,000 cases of autism diagnosed in the US every year.

Initial studies done in the 1960s pointed to four-to-five cases of autism in 10,000 people, which is why autism was once thought of as a rare condition. However, dramatic increases in autism disorders in the US and throughout the world clearly show that autism is not rare.

Keep in mind that changes in how autism is diagnosed, changes in what is considered autism and changes in how autism cases are reported could account for some of the increases in the number of cases reported.

Who usually gets autism?
Current figures show that autism occurs in all racial, ethnic and social groups. These statistics also show that boys are three-to-four times more likely to be affected by autism than girls are. In addition, if a family has one child with autism, there is a 5 to10 percent chance that the family will have another child with autism. In contrast, if a family does not have a child with autism, there is only a 0.1 to 0.2 percent chance that the family will have a child with autism.

When do people usually show signs of autism?
In most cases, the symptoms of autism are measurable by certain screening tools at 18 months of age. However, parents and experts in autism treatment can usually detect symptoms before this time. In general, a formal diagnosis of autism can be made when a child is two, but is usually made when a child is between two and three, when he or she has a noticeable delay in developing language skills.

Recent studies show that at least 20 percent of children with autism experienced a "regression,"" as reported by their parents. This means that the children had a mostly normal development, but then had a loss of social or communication skills. To date, however, there is little information about this type of regression, such as the age it seems to start, how severe it is, and what, if anything, triggers it. NICHD researchers are looking into a variety of possible causes for both early onset and regressive

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