What Causes ASDs?

It is suspected that there may be multiple causes for ASD due to a complex interaction of genetic and environmental factors. Family studies have shed the most light on the genetic contribution to autism. Studies of twins have shown that in identical twins there is about a 75% rate of both twins having autism, while in non-identical twins this occurs about 3% of the time. The inheritance pattern is complex and suggests that a number of genes are involved.

For the majority of people with ASDs, the cause is not known; however, ASD tends to occur more frequently than expected among individuals who have certain other medical conditions, including Fragile X syndrome, tuberous sclerosis, congenital rubella syndrome, and untreated phenylketonuria (PKU). Some harmful substances ingested during pregnancy also have been associated with an increased risk of autism, specifically, the prescription drug thalidomide.

What are CDC's efforts?

CDC has established a collaborative autism research network to explore potential causes and factors that make it more likely that a child will have autism. Some of the theories being investigated include infection and immune function, hormones and reproductive factors, genetic factors, gastrointestinal factors, socio-demographic factors, and others.

CADDRE: Centers of Excellence for Autism and Developmental Disabilities Research and Epidemiology

The Children's Health Care Act of 2000 required the Centers for Disease Control and Prevention (CDC) to establish centers of excellence. The National Center on Birth Defects and Developmental Disabilities (NCBDDD) at CDC funded five Centers for Autism and Developmental Disabilities Research and Epidemiology (CADDRE).

If you would like to learn more about a specific genetic condition that you think could cause an ASD, you can go to the National Library of Medicine's Genetics Home Reference Web site. Information on each genetic condition includes symptoms, how common it is, related genes, treatments, and links to resources where you can learn more about the condition. The Genetics Home Reference also can help you learn more about genetics, including genetic testing, genetic counseling, and gene therapy.

There is no known cure for ASDs. However, early and intensive education can help children grow and learn new skills. The goal of these efforts is to help with the difficult symptoms of an ASD in a child and to improve the child's skills that help him or her talk, interact, play, learn, and care for his or her needs. Medicines can relieve symptoms and be helpful for some people, but structured teaching of skills (often called behavioral intervention) is currently the most effective treatment.

About the Author

The Centers for Disease Control and Prevention (CDC) is one of the 13 major operating components of the Department of Health and Human Services (HHS), which is the principal agency in the United States government for protecting the health and safety of all Americans and for providing essential human services, especially for those people who are least able to help themselves.