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Graphic: Q and A

Q: Do vaccines cause autism spectrum disorder (ASD)?

A: Many studies that 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)External, which is working with the National Vaccine Advisory Committee (NVAC)External 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.

For more information about vaccines and ASD, see:

Immunization Safety Office

Chart of CDC’s Vaccine and ASD Research Cdc-pdf[PDF – 357 KB]

Q: Is there an ASD epidemic?

A: More people than ever before are being diagnosed with an ASD. It is unclear exactly 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. We believe the increase in the diagnosis of ASD is likely due to a combination of these factors.

CDC is working with partners to study the prevalence of ASD over time, so that we can find out if the number of children with these disorders is rising, dropping, or staying the same.

We do know that ASD are more common than we thought before and should be considered an important public health concern.

There is still a lot to learn about ASD. In addition, increased concern in the communities, continued demand for services, and reports estimating a prevalence of about 1.7 percent show the need for a coordinated and serious national response to improve the lives of people with ASD.

Learn more about the number of people with ASD »

Q: Can adults be diagnosed with an ASD?

A: Yes, adults can be diagnosed with an ASD. Diagnosis includes looking at the person’s medical history, watching the person’s behavior, and giving the person some psychological tests. But, it can be more challenging to diagnose an adult because it is not always possible to know about the person’s development during the first few years of life, and a long history of other diagnoses may complicate an ASD diagnosis. Because the focus of ASD has been on children, we still have much to learn about the prevalence and causes of ASD across the lifespan. Behavioral interventions can be effective for adults coping with a new diagnosis of autism.

Photo: child working with adult
Q: What are mitochondrial diseases?

A: Mitochondria are tiny parts of almost every cell in your body. Mitochondria are like the power house of the cells. They turn sugar and oxygen into energy that the cells need to work. In mitochondrial diseases, the mitochondria cannot efficiently turn sugar and oxygen into energy, so the cells do not work the way they should.

There are many types of mitochondrial disease, and they can affect different parts of the body: the brain, kidneys, muscles, heart, eyes, ears, and others. Mitochondrial diseases can affect one part of the body or many parts. The effects can be mild or very serious.

Not everyone with a mitochondrial disease will show symptoms. However, among the mitochondrial diseases that tend to affect children, symptoms usually appear in the toddler and preschool years.

Q: Is there a link between mitochondrial diseases and ASD?

A: A child with an ASD may or may not have a mitochondrial disease. When children have both an ASD and a mitochondrial disease, they sometimes have other problems too, including epilepsy, problems with muscle tone, or movement disorders.

More research is needed to find out how common it is for people to have an ASD and a mitochondrial disease. Right now, it seems rare. In general, more research about mitochondrial disease and ASDs is needed.

Learn more about mitochondrial diseases »


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  1. Data Accountability Center. Data tables for OSEP state reported data: IDEA Part B child count. 2010. [cited 2012 May]. Available at:
  2. Metropolitan Atlanta Developmental Disabilities Surveillance Program. Available at:
  3. Karapurkar Bhasin T, Brocksen S, Nonkin Avchen R, Van Naarden Braun K. Prevalence of four developmental disabilities among children aged 8 years—The Metropolitan Atlanta Developmental Disabilities Surveillance Program, 1996 and 2000. Morbidity and Mortality Weekly Report 2006;55(SS01):1-9.