Autism What are the causes and risk factors?

We do not know all of the causes of ASD. However, we have learned that there are likely many causes for multiple types of ASD. There may be many different factors that make a child more likely to have an ASD, including environmental, biologic and genetic factors.

• Most scientists agree that genes are one of the risk factors that can make a person more likely to develop ASD.
• Children who have a sibling with ASD are at a higher risk of also having ASD.
• ASD tends to occur more often in people who have certain genetic or chromosomal conditions, such as fragile X syndrome or tuberous sclerosis.
• When taken during pregnancy, the prescription drugs valproic acid and thalidomide have been linked with a higher risk of ASD.
• There is some evidence that the critical period for developing ASD occurs before, during, and immediately after birth.
• Children born to older parents are at greater risk for having ASD.

ASD continues to be an important public health concern. Like the many families living with ASD, CDC wants to find out what causes the disorder. Understanding the factors that make a person more likely to develop ASD will help us learn more about the causes. We are currently working on one of the largest U.S. studies to date, called Study to Explore Early Development (SEED). SEED is looking at many possible risk factors for ASD, including genetic, environmental, pregnancy, and behavioral factors.

Research

There is still a lot to learn about ASD. Research on ASD has increased a great deal in recent years and CDC is part of the larger group of public and private organizations working to better understand ASD through research. Like the many families living with ASD, CDC considers ASD an important public health concern. CDC is committed to continuing to provide essential data on ASD, search for risk factors and causes, and develop resources that help identify children with ASD as early as possible.

Recent efforts to coordinate autism research are reflected in the “Strategic Plan for Autism Spectrum Disorder Research” by the Interagency Autism Coordinating Committee (IACC)

 

 

 

Determining How Many People Have ASD

More people than ever before are being diagnosed with ASD. It is unclear how much of this increase is due to a broader definition of ASD and better efforts in diagnosis. However, a true increase in the number of people with an ASD cannot be ruled out. The increase in ASD diagnosis is likely due to a combination of these factors.

By studying the number of children with ASD at different points in time, CDC can find out if the number is rising, dropping, or staying the same. We also can compare the number of children with ASD in different areas of the country and among different groups of people. This information can help direct our research into potential factors that might put children at risk for ASD, and can help communities direct their outreach efforts to those who need it most.

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Understanding Risk Factors and Causes

We do not know all of the causes of ASD. However, we have learned that there are likely many causes for multiple types of ASD. There may be many different factors that make a child more likely to have an ASD, including environmental and genetic factors.

• Most scientists agree that genes are one of the risk factors that can make a person more likely to develop ASD.
• Children who have a sibling with ASD are at a higher risk of also having ASD.
• ASD tends to occur more often in people who have certain genetic or chromosomal conditions, such as fragile X syndrome or tuberous sclerosis.
• When taken during pregnancy, the prescription drugs valproic acid and thalidomide have been linked with a higher risk of ASD.
• There is some evidence that the critical period for developing ASD occurs before, during, and immediately after birth.
• Children born to older parents are at greater risk for having ASD.

Vaccines Safety

Many studies have looked at whether there is a relationship between vaccines and autism spectrum disorder (ASD). To date, the studies continue to show that vaccines are not associated with ASD.

However, CDC knows that some parents and others still have concerns. To address these concerns, CDC is part of the Inter-Agency Autism Coordinating Committee (IACC), which is working with the National Vaccine Advisory Committee (NVAC) on this issue. The job of the NVAC is to advise and make recommendations regarding the National Vaccine Program. Communication between the IACC and NVAC will allow each group to share skills and knowledge, improve coordination, and promote better use of research resources on vaccine topics.