What Is Autism?
- Autism is a complex, life-long biological disorder of development that results in
social interaction problems, communication difficulties, and restrictive or
repetitive interests and behaviors. The prevalence of autism estimates run from
approximately one-in-500 children, to one-in-1000 children, who
might be affected by some form of the disorder.* (See the reference listed in
the Autism and Vaccine Research fact sheet.)
- Autism can be reliably diagnosed by or before age three. Parents and expert
clinicians can usually detect symptoms during infancy, although a formal diagnosis
is generally not made until the child fails to develop functional language by age
two. Approximately 20 percent of children with autism reportedly experience a
"regression"; that is, they have apparently normal development followed by
a loss of communication and social skills.
- Boys are three-to-four times more likely to be affected by autism than girls.
Autism occurs in all racial, ethnic, and social groups.
- Although there is currently no known cure for autism, autism is treatable. Persons
with autism can make progress if they receive appropriate, individual intervention.
Pre-school children who receive intensive, individualized, behavioral interventions
show remarkable progress.** (See the reference listed in the Autism and Vaccine
Research fact sheet.) In addition, limited pharmacological interventions are
available to treat specific symptoms of autism.
What Causes Autism?
- In the majority of cases, no specific underlying cause can be identified. However,
a variety of factors are being investigated. These include infectious, metabolic,
genetic, and environmental factors.
- A working group, convened by the National Institutes of Health (NIH) in 1995,
reached a consensus that autism probably results from a genetic susceptibility that
involves multiple genes.
- To date, genetic causes for one disorder commonly accompanied by autism and one
autism spectrum disorder (ASD) have been identified�Fragile X and Rett Syndrome,
respectively�and genetic "hotspots" for more classic autism have been
indicated. Fragile X is the most common, genetically inherited form of mental
retardation currently known and produces many of the same behaviors and symptoms as
autism. Rett Syndrome, which affects only girls, is a progressive brain disease that
produces a loss of language/social skills that is similar to autism and is
classified as an autism spectrum disorder.*** (See the reference listed in the
Autism and Vaccine Research fact sheet.)
- NIH research on possible genetic, infectious, immunological, and environmental
causes and mechanisms of autism is underway.
Is There A Relationship Between Autism And Vaccines?
- To date, there is no conclusive evidence that any vaccine increases the risk of
developing autism or any other behavior disorder.
- Several epidemiological studies show no causal association between the measles/
mumps/ rubella (MMR) vaccine (or other measles-containing vaccines) and autism. In
January 1990, the Institute of Medicine (IOM) concluded that there was no evidence
to indicate a causal relationship between autism and the
diphtheria/tetanus/pertussis (DTP) vaccine or the pertussis component of the DTP
vaccine. In 2001, the IOM concluded that there is no causal relationship, at a
population level, between the MMR vaccine and ASDs.
- Currently, no study provides definitive evidence of an association between autism
and vaccines. However, continued research is needed to examine the mechanisms of
autism and any possible relationship to vaccines.
- For more information on autism and autism research, contact the National Institute
of Child Health and Human Development (NICHD) Clearinghouse at 1-800-370-2943, or
visit these NIH web sites:
http://www.nlm.nih.gov/medlineplus/autism.html
http://www.nichd.nih.gov/autism/
The CDC�s National Center on Birth Defects and Developmental Disabilities also
provides information about autism on their web site, at: http://www.cdc.gov/ncbddd/dd/ddautism.htm.
For more information on vaccines and vaccine safety, contact the National
Immunization Program (NIP) at 1-800-232-2522 (English) or 1-800-232-0233 (Spanish), or
visit the NIP web site at http://www.cdc.gov/nip.
MEDLINEplus Health Information: http://www.nlm.nih.gov/medlineplus/autism.html
NIH, National Institute of Child Health and Human Development: http://www.nichd.nih.gov/
CDC, National Immunization Program: http://www.cdc.gov/nip
Last updated: August 2001
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