What is autism?
spectrum disorder (ASD) is a range of complex neurodevelopment
disorders, characterized by social impairments, communication
difficulties, and restricted, repetitive, and stereotyped patterns of
behavior. Autistic disorder, sometimes called autism or classical ASD,
is the most severe form of ASD, while other conditions along the
spectrum include a milder form known as Asperger syndrome, and childhood
disintegrative disorder and pervasive developmental disorder not
otherwise specified (usually referred to as PDD-NOS). Although ASD
varies significantly in character and severity, it occurs in all ethnic
and socioeconomic groups and affects every age group. Experts estimate
that 1 out of 88 children age 8 will have an ASD (Centers for Disease
Control and Prevention: Morbidity and Mortality Weekly Report, March 30,
2012). Males are four times more likely to have an ASD than females.
What are some common signs of autism?
hallmark feature of ASD is impaired social interaction. As early as
infancy, a baby with ASD may be unresponsive to people or focus intently
on one item to the exclusion of others for long periods of time. A
child with ASD may appear to develop normally and then withdraw and
become indifferent to social engagement.
Children with an ASD may
fail to respond to their names and often avoid eye contact with other
people. They have difficulty interpreting what others are thinking or
feeling because they can’t understand social cues, such as tone of voice
or facial expressions, and don’t watch other people’s faces for clues
about appropriate behavior. They lack empathy.
with an ASD engage in repetitive movements such as rocking and twirling,
or in self-abusive behavior such as biting or head-banging. They also
tend to start speaking later than other children and may refer to
themselves by name instead of “I” or “me.” Children with an ASD don’t
know how to play interactively with other children. Some speak in a
sing-song voice about a narrow range of favorite topics, with little
regard for the interests of the person to whom they are speaking.
with characteristics of an ASD may have co-occurring conditions,
including Fragile X syndrome (which causes mental retardation), tuberous
sclerosis, epileptic seizures, Tourette syndrome, learning
disabilities, and attention deficit disorder. About 20 to 30 percent of
children with an ASD develop epilepsy by the time they reach adulthood.
How is autism diagnosed?
varies widely in severity and symptoms and may go unrecognized,
especially in mildly affected children or when it is masked by more
debilitating handicaps. Very early indicators that require evaluation
by an expert include:
- no babbling or pointing by age 1
- no single words by 16 months or two-word phrases by age 2
- no response to name
- loss of language or social skills
- poor eye contact
- excessive lining up of toys or objects
- no smiling or social responsiveness.
Later indicators include:
- impaired ability to make friends with peers
- impaired ability to initiate or sustain a conversation with others
- absence or impairment of imaginative and social play
- stereotyped, repetitive, or unusual use of language
- restricted patterns of interest that are abnormal in intensity or focus
- preoccupation with certain objects or subjects
- inflexible adherence to specific routines or rituals.
care providers will often use a questionnaire or other screening
instrument to gather information about a child’s development and
behavior. Some screening instruments rely solely on parent
observations, while others rely on a combination of parent and doctor
observations. If screening instruments indicate the possibility of an
ASD, a more comprehensive evaluation is usually indicated.
comprehensive evaluation requires a multidisciplinary team, including a
psychologist, neurologist, psychiatrist, speech therapist, and other
professionals who diagnose children with ASDs. The team members will
conduct a thorough neurological assessment and in-depth cognitive and
language testing. Because hearing problems can cause behaviors that
could be mistaken for an ASD, children with delayed speech development
should also have their hearing tested.
Children with some
symptoms of an ASD but not enough to be diagnosed with classical autism
are often diagnosed with PDD-NOS. Children with autistic behaviors but
well-developed language skills are often diagnosed with Asperger
syndrome. Much rarer are children who may be diagnosed with childhood
disintegrative disorder, in which they develop normally and then
suddenly deteriorate between the ages of 3 to 10 years and show marked
What causes autism?
aren’t certain about what causes ASD, but it’s likely that both
genetics and environment play a role. Researchers have identified a
number of genes associated with the disorder. Studies of people with
ASD have found irregularities in several regions of the brain. Other
studies suggest that people with ASD have abnormal levels of serotonin
or other neurotransmitters in the brain. These abnormalities suggest
that ASD could result from the disruption of normal brain development
early in fetal development caused by defects in genes that control brain
growth and that regulate how brain cells communicate with each other,
possibly due to the influence of environmental factors on gene function.
While these findings are intriguing, they are preliminary and require
further study. The theory that parental practices are responsible for
ASD has long been disproved.
What role does inheritance play?
and family studies strongly suggest that some people have a genetic
predisposition to autism. Identical twin studies show that if one twin
is affected, there is up to a 90 percent chance the other twin will be
affected. There are a number of studies in progress to determine the
specific genetic factors associated with the development of ASD. In
families with one child with ASD, the risk of having a second child with
the disorder is approximately 5 percent, or one in 20. This is greater
than the risk for the general population. Researchers are looking for
clues about which genes contribute to this increased susceptibility. In
some cases, parents and other relatives of a child with ASD show mild
impairments in social and communicative skills or engage in repetitive
behaviors. Evidence also suggests that some emotional disorders, such
as bipolar disorder, occur more frequently than average in the families
of people with ASD.
Do symptoms of autism change over time?
many children, symptoms improve with treatment and with age. Children
whose language skills regress early in life—before the age of 3—appear
to have a higher than normal risk of developing epilepsy or seizure-like
brain activity. During adolescence, some children with an ASD may
become depressed or experience behavioral problems, and their treatment
may need some modification as they transition to adulthood. People with
an ASD usually continue to need services and supports as they get
older, but many are able to work successfully and live independently or
within a supportive environment.
How is autism treated?
is no cure for ASDs. Therapies and behavioral interventions are
designed to remedy specific symptoms and can bring about substantial
improvement. The ideal treatment plan coordinates therapies and
interventions that meet the specific needs of individual children. Most
health care professionals agree that the earlier the intervention, the
Therapists use highly structured and intensive skill-oriented training
sessions to help children develop social and language skills, such as
Applied Behavioral Analysis. Family counseling for the parents and
siblings of children with an ASD often helps families cope with the
particular challenges of living with a child with an ASD.
Doctors may prescribe medications for treatment of specific
autism-related symptoms, such as anxiety, depression, or
obsessive-compulsive disorder. Antipsychotic medications are used to
treat severe behavioral problems. Seizures can be treated with one or
more anticonvulsant drugs. Medication used to treat people with
attention deficit disorder can be used effectively to help decrease
impulsivity and hyperactivity.
There are a number of controversial therapies or interventions
available, but few, if any, are supported by scientific studies.
Parents should use caution before adopting any unproven treatments.
Although dietary interventions have been helpful in some children,
parents should be careful that their child’s nutritional status is
What research is being done?
Where can I get more information?
1997, at the request of Congress, the National Institutes of Health
(NIH) formed its Autism Coordinating Committee (NIH/ACC) to enhance the
quality, pace and coordination of efforts at the NIH to find a cure for
The NIH/ACC involves the participation of seven NIH Institutes and
Centers: the National Institute of Neurological Disorders and Stroke
(NINDS), the Eunice Kennedy Shriver National Institute of Child
Health and Human Development, the National Institute of Mental Health,
the National Institute on Deafness and Other Communication Disorders,
the National Institute of Environmental Health Sciences, the National
Institute of Nursing Research, and the National Center on Complementary
and Alternative Medicine. The NIH/ACC has been instrumental in the
understanding of and advances in ASD research. The NIH/ACC also
participates in the broader Federal Interagency Autism Coordinating
Committee (IACC) that is composed of representatives from various
component agencies of the U.S. Department of Health and Human Services,
as well as the U.S. Department of Education and other government
In fiscal years 2007 and 2008, NIH began funding
the 11 Autism Centers of Excellence (ACE), coordinated by the NIH/ACC.
The ACEs are investigating early brain development and functioning,
social interactions in infants, rare genetic variants and mutations,
associations between autism-related genes and physical traits, possible
environmental risk factors and biomarkers, and a potential new
more information on neurological disorders or research programs funded
by the National Institute of Neurological Disorders and Stroke, contact
the Institute's Brain Resources and Information Network (BRAIN) at:
P.O. Box 5801
Bethesda, MD 20824
Information also is available from the following organizations:
|Association for Science in Autism Treatment
P.O. Box 188
Crosswicks, NJ 08515-0188
|Autism National Committee (AUTCOM)
P.O. Box 429
Forest Knolls, CA 94933
|Autism Network International (ANI)
P.O. Box 35448
Syracuse, NY 13235-5448
|Autism Research Institute (ARI)
4182 Adams Avenue
San Diego, CA 92116
|Autism Science Foundation
419 Lafayette Street
New York, NY 10003
|Autism Society of America
4340 East-West Highway
Bethesda, MD 20814
Tel: 301-657-0881 800-3AUTISM (328-8476)
|Autism Speaks, Inc.
1 East 33rd Street
New York, NY 10016
Tel: 212-252-8584 (888) 288-4762
|Birth Defect Research for Children, Inc.
976 Lake Baldwin Lane
Orlando, FL 32814
|MAAP Services for Autism, Asperger Syndrome, and PDD
P.O. Box 524
Crown Point, IN 46308
|National Dissemination Center for Children with Disabilities
U.S. Dept. of Education, Office of Special Education Programs
1825 Connecticut Avenue NW, Suite 700
Washington, DC 20009
Tel: 800-695-0285 202-884-8200
|National Institute of Child Health and Human Development (NICHD)
National Institutes of Health, DHHS
31 Center Drive, Rm. 2A32 MSC 2425
Bethesda, MD 20892-2425
|National Institute on Deafness and Other Communication Disorders Information Clearinghouse
1 Communication Avenue
Bethesda, MD 20892-3456
Tel: 800-241-1044 800-241-1055 (TTD/TTY)
|National Institute of Environmental Health Sciences (NIEHS)
National Institutes of Health, DHHS
111 T.W. Alexander Drive
Research Triangle Park, NC 27709
|National Institute of Mental Health (NIMH)
National Institutes of Health, DHHS
6001 Executive Blvd. Rm. 8184, MSC 9663
Bethesda, MD 20892-9663
Tel: 301-443-4513/866-415-8051 301-443-8431 (TTY)
"Autism Fact Sheet
," NINDS. Publication date September 2009.
NIH Publication No. 09-1877
Back to Autism Information Page
See a list of all NINDS Disorders