N I C H D
What We Know
Eunice Kennedy Shriver
National Institute of
Child Health and
Eunice Kennedy Shriver National Institute of Child
Health and Human Development (NICHD), part of
the National Institutes of Health (NIH), within the U.S.
Department of Health and Human Services, is one of many
federal agencies working to understand autism. The NICHD
supports and conducts research on what causes autism, how
many people have autism, how best to treat the symptoms
of autism, and other topics.
Even though autism was first described in the 1940s, little was
really known about the disorder until the 1990s. Even today,
there is a great deal that researchers, scientists, and health care
providers don’t know about autism.
But there are things that we do know about autism. This fact
sheet offers broad information about autism and answers
some of the more common questions that parents and
families often have about the disorder. You can get more
detailed information on these topics from the sources listed in
References section. Ke p in mind that the articles listed
are geared toward scientists and researchers, so the
information is more technical than what is presented here.
Knowledge of autism is always growing as research examines
more and different sides of the disorder. The NICHD joins
other federal agencies, organizations, and support groups in
helping those with autism achieve their full potential to live
healthy, productive lives.
U.S. Department of Health
and Human Services
National Institutes of Health
AUTISM RESEARCH AT THE NICHD
What is autism?
calm themselves down. They may flap their
to tell you they are happy, or they might
is a complex neurobiological disorder of
themselves to tell you they are not. Some
that lasts throughout a person’s life.
with autism never learn how to talk.
is sometimes called a developmental disability
behaviors not only make life challenging
it usually starts before age three, in the
people who have autism, but also take a toll
their families, their health care providers, their
because it causes
and anyone who comes in contact
Check the Glossary on
or problems in
pages 1415 to learn
how to say the bolded
arise from infancy
words and what
different people with autism can have
different features or symptoms, health care
think of autism as a “spectrum”
main signs and symptoms of autism
group of disorders with a range of
language, social behavior, and behaviors
features. Based on their specific strengths
objects and routines:
weaknesses, people with autism spectrum
disorders (ASDs) may have mild symptoms or
more serious symptoms, but they all have an
verbal (spoken) and
(unspoken, such as pointing, eye
This fact sheet uses the terms “ASD” and
autism” to mean the same thing.
interactions—such as sharing emotions,
What conditions are in the
how others think and feel
called empathy), and holding a
as well as the amount of time a
the ASD category includes:
spends interacting with others
disorder (also called “classic” autism)
or repetitive behaviors—often called
behaviors, such as repeating
or actions, obsessively following
or schedules, playing with toys or
Developmental Disorder Not
in repetitive and sometimes
Specified (or atypical autism)
ways, or having very specific and
ways of arranging items
some cases, health care providers use a
term—pervasive developmental disorders
with autism might have problems talking
(PDD)—to describe autism. The PDD category
you, or they might not look you in the eye
the ASDs mentioned above and:
you talk to them. They may have to line
disintegrative disorder, and
their pencils before they can pay attention, or
may say the same sentence again and again
Depending on specific symptoms, a person with Because
the disorder is so complex, and because
may fall into the ASD or the PDD
two people with autism are exactly alike,
Sometimes, the terms “ASD” and
is probably the result of many causes.
PDD” are used to mean the same thing because
autism is in both categories.
Is there a link between autism
To date, there is no conclusive scientific evidence
What causes autism?
any part of a vaccine or any combination of
vaccines causes autism, even though researchers
have carried out many studies to answer this
don’t know exactly what causes autism
important question. There is also no proof that
any material used to make or preserve vaccines
plays a role in causing autism.
evidence supports the idea that genetic
factors—that is, genes, their function, and their
Although there have been reports of studies that
one of the main underlying
relate vaccines to autism, the findings have not
of ASDs. But, researchers aren’t looking
held up under further investigation. Researchers
just one gene. Current evidence suggests
have been unable to replicate the studies that
as many as 12 or more genes on different
found a link betwe n autism and
may be involved in autism, to
There is a great deal of research and discussion
genes may place a person at greater risk
on the topic of vaccines and autism—too much
autism, called susceptibility. Other genes
to cover here. The U.S. Centers for Disease
cause specific symptoms or determine how
Control and Prevention (CDC) conducts and
those symptoms are. Or, genes with
supports most of the federal epidemiological
or mutations might add to the
studies that seek to answer questions about
of autism because the genes or gene
vaccines and autism.
aren’t working properly.
Currently, the CDC provides the most accurate
has also shown that environmental
and uptodate information about research on
such as viruses, may also play a role in
autism and vaccine research, both supported by
the federal government and funded
independently. For more information, visit
some researchers are examining genes and
factors, other researchers are
at possible neurological, infectious,
metabolic, and immunologic factors that may be
involved in autism.
AUTISM RESEARCH AT THE NICHD
How many people
Is autism more common in
certain groups of people?
Currently, researchers don’t know the exact
figures show that autism occurs in all
of people with an ASD in the United
ethnic, and social groups equally, with
individuals in one group no more or less likely to
ASDs than those in other groups. Three
use different ways to determine
groups are at higherthannormal risk for ASDs,
prevalence that often give different results.
Some estimates of prevalence rely on previously
● Boys. Statistics show that boys are thre to
studies. Researchers review all the
times more likely5 to be affected by
data on a topic and take the averages
than are girls.
these calculations to determine prevalence.
Independent researchers3 recently conducted two
● Siblings of those with ASDs. Among families
reviews. Based on these studies, the best
have one child with an ASD, recurrence of
estimate4 of the prevalence of
in another sibling is betwe n6 2 percent
in the United States is that one child in
8 percent, a figure much higher than in the
children has an ASD.
● People with certain other developmental disorders.
Is autism more common now than
For certain disorders, including Fragile X
it was in the past?
syndrome, mental retardation, and tuberous
are not certain whether autism is
sclerosis, autism is common in addition to the
prevalent now than in the past for a
symptoms of the disorder.
of reasons. Although more cases of
autism are being identified, it is not clear why.
Some of the increase may result from better
education about the symptoms of autism or
When do people usually show
more accurate diagnoses of autism.
signs of autism?
The new definition of autism as a spectrum
means that even people with mild
number of the behavioral symptoms7 of
can be classified as having an ASD,
are observable by 18 months of age,
could also account for the increase in
problems with eye contact, not
cases. As research moves forward
to one’s name, joint attention
the current definition of ASDs, more
underdeveloped skills in pretend play
numbers may be available to answer this
imitation, and problems with nonverbal
Possible Red Flags for Autism11
studies also note that, although more
subtle, some signs of autism are detectable at
● The child does not respond to his/her name.
months8 of age.
● The child cannot explain what he/she wants.
general, the average age of autism diagnosis is
The child’s language skills are slow to develop or speech is
three years old. In many cases, a delay
in the child’s starting to speak around age two
● The child doesn’t follow directions.
problems to parents’ attention, even
● At times, the child seems to be deaf.
other, less noticeable signs may be
at an earlier age.9
The child seems to hear sometimes, but not other times.
● The child doesn’t point or wave “byebye.”
also show that a subgroup of children
● The child used to say a few words or babble, but now
ASDs experiences a “regression,” meaning
stop using the language, play, or social skills
had already learned. This regression usually
The child throws intense or violent tantrums.
between the first and second birthdays.
● The child has odd movement patterns.
● The child is overly active, uncooperative, or resistant.
are still learning about the features
of regression in ASDs, and whether the features
● The child doesn’t know how to play with toys.
from those shown by individuals who
● The child doesn’t smile when smiled at.
signs of autism in early life.
● The child has poor eye contact.
● The child gets “stuck” doing the same things over and over
and can’t move on to other things.
What are some of the
● The child seems to prefer to play alone.
possible signs of autism?
● The child gets things for him/herself only.
● The child is very independent for his/her age.
caregivers, family members, teachers,
others who spend a lot of time with
The child does things “early” compared to other children.
can look for “red flags.” Some may
● The child seems to be in his/her “own world.”
a delay in one or more areas of
● The child seems to tune people out.
while others are more typical of
ASDs. A list of red flags appears to the right.
● The child is not interested in other children.
● The child walks on his/her toes.
● The child shows unusual attachments to toys, objects, or
schedules (i.e., always holding a string or having to put
socks on before pants).
● Child spends a lot of time lining things up or putting things
in a certain order.
AUTISM RESEARCH AT THE NICHD
In addition, your child’s health care provider will Your
child’s health care provider will note your
your child for an evaluation if you report
and concerns, will ask some other
of the behaviors listed below; such an
and will determine the best plan of
would consider ASDs, among other
In some cases, the health care provider
will ask you to complete a questionnaire about
your child to get more specific information
If the child…
about symptoms. To rule out certain conditions,
the health care provider will also test your child’s
not babble or coo by 12 months of age
and check your child’s lead level before
deciding on a course of action.
not gesture (point, wave, grasp, etc.) by
12 months of age
If red flags are present, and if the lead and
hearing tests show no problems, your child’s
not say single words by 16 months
care provider may refer you to a specialist
in child development or another specialized
health care provider. The specialist will conduct
not say twoword phrases on his or her
number of tests to determine whether or not
(rather than just repeating what someone
child has autism or an ASD.
to him or her) by 24 months of age
What if I don’t notice any symptoms?
ANY loss of ANY language or social
skill at ANY age
If you don’t report any of these signs, your
child’s health care provider will continue to check
for problems at every wellbaby and wellchild
visit.14 If your child’s health care provider does
What should I do if I think my
routinely check your child with such tests,
you should ask that he or she do so.
child has a developmental
problem or autism?
In this developmental screening, the provider
questions related to normal development
your child’s health care provider immediately
can help measure your child’s specific
you think something is wrong.
Typically, these questions are similar to
red flags listed earlier. Based on your
to the American Academy of Pediatrics
the health care provider may send your
(AAP) , “Pediatricians should listen carefully to
for further evaluation.
discussing their child’s development.
are reliable sources of information and
AAP recommends15 that health care
concerns should be valued and addresses
ask questions about different aspects
development. These questions include (but
are not limited to) those listed here.
Does your child…15
Is there a cure for autism?
speak as well as other children
date, there is no cure for autism, but
children with ASDs make so much
progress that they no longer show the full
poor eye contact?
of autism when they are older.
as if he/she is in his/her own world?
Research16 shows that early diagnosis and
interventions delivered early in life, such as in
to “tune out” others?
the preschool period, are more likely to result in
smile when smiled at?
positive effects on later skills and
symptoms. The sooner a child begins to get
unable to tell you what he/she wants,
help, the more opportunity for learning. Because
so takes your hand and leads you to what
a young child’s brain is still forming, early
wants, or gets it him/herself?
intervention gives children the best start possible
the best chance of developing their full
trouble following simple directions?
potential. Even so, no matter when a person is
play with toys in a usual way?
with autism, it’s never too late to
benefit from treatment. People of all ages with
bring things to you to “show” you
at all levels of ability generally respond
positively to well designed interventions.
point to interesting things or direct your
Public Law 10877: Individuals with Disabilities
to items of interest?
Education Improvement Act (2004) and Public
Law 10517: Individuals with Disabilities Act, or
unusually long or severe temper
require your child’s primary care
provider to refer you and your family to an early
an unusual attachment to objects,
service. Every state operates an
“hard” ones, such as a flashlight or
intervention program for children from
chain, instead of “soft” ones, such as a
to age three; children with autism should
or stuffed animal?
qualify for these services. Early intervention
programs typically include behavioral methods,
to play alone?
early developmental education, communication
occupational and physical therapy, and
pretend or play “make believe” (if the
structured social play.
is older than age two)?
AUTISM RESEARCH AT THE NICHD
What are the treatments
in mind that other therapies, beyond ABA,
also be effective for persons with autism.
Talk to your health care provider about the best
options for your child.
there is no definitive, single treatment
for ASDs. However, there are a variety of ways
A variety of health care providers can also help
help minimize the symptoms and maximize
individuals with ASDs and their families to work
Persons with an ASD have the best
through different situations.
of using all of their individual capabilities
and skills if they receive appropriate behavioral
● Speechlanguage therapists can help people
other therapies, education, and medication.
autism improve their general ability to
some cases, these treatments can help people
communicate and interact with others
autism function at nearnormal levels.
effectively, as well as develop their speech and
language skills. These therapists may teach
possible treatments for autism are
nonverbal ways of communicating and may
below. If you have a question about
improve social skills that involve
you should talk to a health care
communicating with others. They may also
who specializes in caring for people
help people to bet er use words and sentences,
and to improve rate and rhythm of speech and
Behavioral therapy and other
Occupational therapists can help people with
autism find ways to adjust tasks and conditions
general, behavior management therapy
that match their needs and abilities. Such help
to reinforce wanted behaviors and reduce
may include finding a specially designed
behaviors. At the same time, these
computer mouse and keyboard to ease
also suggest what caregivers should do
communication, or identifying skills that build
or between episodes of problem
on a person’s interests and individual
and what to do during or after these
capabilities. Occupational therapists may also
Behavioral therapy is often based on
do many of the same types of activities as
Applied Behavior Analysis (ABA). Different
physical therapists do (see below).
of ABA commonly used for people
with autism include: Positive Behavioral
● Physical therapists design activities and
and Support (PBS), Pivotal
exercises to build motor control and to
Training (PRT), Incidental Teaching,
improve posture and balance. For example,
Therapy, Verbal Behavior, and Discrete
they can help a child who avoids body contact
Teaching (DTT), among others.
to participate in activities and games with other
Special services are often available to preschool To
qualify for special education services, the
schoolaged children, as well as to teens,
must meet specific criteria as outlined by
the local public school system. In many
and state guidelines. You can contact a
services provided by specialists in the
school principal or special education
setting are free. More intense and
to learn how to have your child
help is available through private
to see if he or she qualifies for services
but the family usually has to pay for
services, although some health insurance
plans may help cover the cost.
If your child qualifies for special services, a team
of people, including you and your family,
caregivers, teachers, school psychologists, and
other child development specialists, will work
to design an Individualized
with ASDs are guaranteed free,
Educational Plan (IEP)
your child. An
public education under federal laws.
includes specific academic, communication,
Public Law 10877: Individuals with Disabilities
learning, functional, and socialization
Education Improvement Act (2004) and Public
for a child based on his or her educational
Law 10517: The Individuals with Disabilities
The team also decides how best to carry
Education Act—IDEA (1997) make it possible
the IEP, such as determining any devices or
children with disabilities to get free
assistance the child needs, and identifying
services and educational devices to
developmental specialists who will work
them learn as much as they can. Each child
entitled to these services from age three
high school, or until age 21, whichever
special services team should evaluate and
your child on a regular basis to see
your child is doing and whether any
laws state that children must be taught in
are needed in his or her plan.
least restrictive environment, appropriate for
individual child. This statement does not
number of parents’ organizations, both
that each child must be placed in a regular
and local, provide information on
Instead, the laws mean that the
and educational services and how to
environment should be designed to
these services for a child. Visit
a child’s learning needs, while minimizing
on the child’s access to typical
a listing of these organizations, or check the
experiences and interactions. Educating
with ASDs often includes a combination
of onetoone, small group, and regular
AUTISM RESEARCH AT THE NICHD
used to treat the symptoms of
autism20 may include (but are not limited to):
there is no medication that can cure
ASDs or all of the associated symptoms.
● Selective serotonin reuptake inhibitors (SSRIs)
the Food and Drug Administration
are a group of antidepressants that treat
(FDA) has not approved any drugs specifically
problems, such as obsessivecompulsive
the treatment of autism or its causes. But, in
behaviors and anxiety, resulting from an
cases, medication can treat some of the
imbalance in one of the body’s chemical
associated with ASDs.
systems that are sometimes present in autism.
These medications may: reduce the frequency
Please note that the NICHD does not endorse or
and intensity of repetitive behaviors; decrease
support the use of any of these medications for
irritability, tantrums, and aggressive behavior;
treating symptoms of ASDs, or for other conditions
and improve eye contact.
for which the medications are not FDA approved.
● Tricyclics are another type of antidepressant
can improve the behavior of a
used to treat depression and obsessive
with autism. Health care providers often
compulsive behaviors. Although these drugs
medications to deal with a specific behavior,
tend to cause more side effects than the SSRIs,
as reducing selfinjurious behavior. With
sometimes they are more effective for certain
symptom minimized, the person with autism
focus on other things, including learning and
communication. Some of these medications
● Psychoactive or antipsychotic medications affect
serious risks involved with their use; others
the brain of the person taking them. Use of
make symptoms worse at first or may take
this group of drugs is the most widely studied
weeks to become effective.
treatment for autism. In some people with
ASDs, these drugs may decrease hyperactivity,
every medication helps every person with
reduce stereotyped behaviors, and minimize
of autism. Health care providers
withdrawal and aggression.
prescribe medications on a trial basis, to
see if it helps. Your child’s health care provider
● Stimulants may be useful in increasing focus
have to try different dosages or different
and decreasing hyperactivity in people with
of medications to find the most
autism, particularly in higherfunctioning
plan. Families, caregivers, and health
individuals. Because of the risk of side effects,
providers need to work together to make
health care providers should monitor those
that medications are working and that the
using these drugs carefully and often.
medication plan is safe.
● Antianxiety drugs can help relieve anxiousness
and panic disorders associated with autism.