Autism Spectrum Disorders (ASDs)

N I C H D
Autism Overview:
What We Know
Eunice Kennedy Shriver
National Institute of
Child Health and
The
Human Development
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
the
Autism
References section. Ke p in mind that the articles listed
are geared toward scientists and researchers, so the
Research at
information is more technical than what is presented here.
the NICHD
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
www.nichd.nih.gov

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AUTISM RESEARCH AT THE NICHD
to
What is autism?
calm themselves down. They may flap their
arms
Autism
to tell you they are happy, or they might
hurt
is a complex neurobiological disorder of
development
themselves to tell you they are not. Some
people
that lasts throughout a person’s life.
It
with autism never learn how to talk.
These
is sometimes called a developmental disability
because
behaviors not only make life challenging
for
it usually starts before age three, in the
developmental
people who have autism, but also take a toll
on
period,
and
their families, their health care providers, their
teachers,
because it causes
delays
and anyone who comes in contact
Check the Glossary on
with
or problems in
many
them.
pages 14­15 to learn
different skills
that
how to say the bolded
Because
arise from infancy
to
words and what
different people with autism can have
they mean.
very
adulthood.
different features or symptoms, health care
providers
The
think of autism as a “spectrum”
disorder—a
main signs and symptoms of autism
involve1
group of disorders with a range of
similar
language, social behavior, and behaviors
concerning
features. Based on their specific strengths
and
objects and routines:
weaknesses, people with autism spectrum
disorders (ASDs) may have mild symptoms or
● Communication—both
more serious symptoms, but they all have an

verbal (spoken) and
non­verbal
ASD.
(unspoken, such as pointing, eye
contact,
This fact sheet uses the terms “ASD” and
“
or smiling)
autism” to mean the same thing.
● Social

interactions—such as sharing emotions,
understanding
What conditions are in the
how others think and feel
(sometimes
ASD category?
called empathy), and holding a
conversation,
Currently,
as well as the amount of time a
person
the ASD category includes:
spends interacting with others
● Autistic

disorder (also called “classic” autism)
● Routines

or repetitive behaviors—often called
stereotyped
Asperger
behaviors, such as repeating
words
●
syndrome
or actions, obsessively following
routines
Pervasive
or schedules, playing with toys or
objects
●
Developmental Disorder Not
Otherwise
in repetitive and sometimes
inappropriate
Specified (or atypical autism)
ways, or having very specific and
inflexible
In
ways of arranging items
some cases, health care providers use a
broader
People
term—pervasive developmental disorders
with autism might have problems talking
with
(PDD)—to describe autism. The PDD category
includes
you, or they might not look you in the eye
when
the ASDs mentioned above and:
Childhood
you talk to them. They may have to line
up
disintegrative disorder, and
their pencils before they can pay attention, or
they
Rett syndrome.
may say the same sentence again and again
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AUTISM OVERVIEW
Depending on specific symptoms, a person with Because
autism
the disorder is so complex, and because
may fall into the ASD or the PDD
no
category.
two people with autism are exactly alike,
Sometimes, the terms “ASD” and
autism
“
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
and vaccines?
To date, there is no conclusive scientific evidence
that
What causes autism?
any part of a vaccine or any combination of
vaccines causes autism, even though researchers
Scientists
have carried out many studies to answer this
don’t know exactly what causes autism
at
important question. There is also no proof that
this time.
any material used to make or preserve vaccines
Much
plays a role in causing autism.
evidence supports the idea that genetic
factors—that is, genes, their function, and their
interactions—are
Although there have been reports of studies that
one of the main underlying
causes
relate vaccines to autism, the findings have not
of ASDs. But, researchers aren’t looking
for
held up under further investigation. Researchers
just one gene. Current evidence suggests
that
have been unable to replicate the studies that
as many as 12 or more genes on different
reportedly
chromosomes
found a link betwe n autism and
may be involved in autism, to
different
vaccines.
degrees.
Some
There is a great deal of research and discussion
genes may place a person at greater risk
for
on the topic of vaccines and autism—too much
autism, called susceptibility. Other genes
may
to cover here. The U.S. Centers for Disease
cause specific symptoms or determine how
severe
Control and Prevention (CDC) conducts and
those symptoms are. Or, genes with
changes
supports most of the federal epidemiological
or mutations might add to the
symptoms
studies that seek to answer questions about
of autism because the genes or gene
products
vaccines and autism.
aren’t working properly.
Research
Currently, the CDC provides the most accurate
has also shown that environmental
factors,
and up­to­date information about research on
such as viruses, may also play a role in
causing
autism and vaccine research, both supported by
autism.
the federal government and funded
While
independently. For more information, visit
some researchers are examining genes and
environmental
http://www.cdc.gov/nip/vacsafe/concerns/autism/
factors, other researchers are
looking
default.htm.
at possible neurological, infectious,
metabolic, and immunologic factors that may be
involved in autism.
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AUTISM RESEARCH AT THE NICHD
How many people
Is autism more common in
have autism?
certain groups of people?
Currently, researchers don’t know the exact
Current
number
figures show that autism occurs in all
of people with an ASD in the United
racial,
States.
ethnic, and social groups equally, with

individuals in one group no more or less likely to
have
Researchers
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.
including:
Some estimates of prevalence rely on previously
published
● Boys. Statistics show that boys are thre to
studies. Researchers review all the
four
published
times more likely5 to be affected by
data on a topic and take the averages
autism
of
than are girls.
these calculations to determine prevalence.
Independent researchers3 recently conducted two
such
● Siblings of those with ASDs. Among families
reviews. Based on these studies, the best
that
conservative
have one child with an ASD, recurrence of
estimate4 of the prevalence of
ASD
ASDs
in another sibling is betwe n6 2 percent
in the United States is that one child in
and
1,000
8 percent, a figure much higher than in the
children has an ASD.
general population.
● People with certain other developmental disorders.
Is autism more common now than
For certain disorders, including Fragile X
it was in the past?
Researchers
syndrome, mental retardation, and tuberous
are not certain whether autism is
more
sclerosis, autism is common in addition to the
primary
prevalent now than in the past for a
number
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
from
When do people usually show
more accurate diagnoses of autism.
signs of autism?
The new definition of autism as a spectrum
disorder
A
means that even people with mild
number of the behavioral symptoms7 of
symptoms
autism
can be classified as having an ASD,
are observable by 18 months of age,
which
including:
could also account for the increase in
problems with eye contact, not
identified
responding
cases. As research moves forward
to one’s name, joint attention
using
problems,
the current definition of ASDs, more
underdeveloped skills in pretend play
definite
and
numbers may be available to answer this
imitation, and problems with non­verbal
question.
communication

and language.
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AUTISM OVERVIEW
Some
Possible Red Flags for Autism11
studies also note that, although more
subtle, some signs of autism are detectable at
eight
● The child does not respond to his/her name.
months8 of age.
● The child cannot explain what he/she wants.
In
●
general, the average age of autism diagnosis is
currently
The child’s language skills are slow to develop or speech is
delayed.
three years old. In many cases, a delay
in the child’s starting to speak around age two
brings
● The child doesn’t follow directions.
problems to parents’ attention, even
though
● At times, the child seems to be deaf.
other, less noticeable signs may be
present
●
at an earlier age.9
The child seems to hear sometimes, but not other times.
Studies10
● The child doesn’t point or wave “bye­bye.”
also show that a subgroup of children
with
● The child used to say a few words or babble, but now
ASDs experiences a “regression,” meaning
they
he/she doesn’t.
stop using the language, play, or social skills
they
●
had already learned. This regression usually
happens
The child throws intense or violent tantrums.
between the first and second birthdays.
● The child has odd movement patterns.
Researchers
● The child is overly active, uncooperative, or resistant.
are still learning about the features
of regression in ASDs, and whether the features
differ
● The child doesn’t know how to play with toys.
from those shown by individuals who
show
● 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.
Parents,
● The child is very independent for his/her age.
caregivers, family members, teachers,
and
●
others who spend a lot of time with
children
The child does things “early” compared to other children.
can look for “red flags.” Some may
mean
● The child seems to be in his/her “own world.”
a delay in one or more areas of
development,
● 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.
5

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AUTISM RESEARCH AT THE NICHD
In addition, your child’s health care provider will Your
send
child’s health care provider will note your
your child for an evaluation if you report
comments
any
and concerns, will ask some other
of the behaviors listed below; such an
questions,
evaluation
and will determine the best plan of
would consider ASDs, among other
action.
possible
In some cases, the health care provider
causes.12
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
● Does
hearing

not babble or coo by 12 months of age
and check your child’s lead level before
deciding on a course of action.
● Does

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
● Does
health

not say single words by 16 months
of
care provider may refer you to a specialist
age
in child development or another specialized
health care provider. The specialist will conduct
● Does
a

not say two­word phrases on his or her
own
number of tests to determine whether or not
(rather than just repeating what someone
your
says
child has autism or an ASD.
to him or her) by 24 months of age
● Has
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
not
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
asks
Tell
questions related to normal development
that
your child’s health care provider immediately
if
can help measure your child’s specific
progress.
you think something is wrong.
Typically, these questions are similar to
the
According
red flags listed earlier. Based on your
answers,
to the American Academy of Pediatrics
13
the health care provider may send your
child
(AAP) , “Pediatricians should listen carefully to
parents
for further evaluation.
discussing their child’s development.
[Parents]
The
are reliable sources of information and
their
AAP recommends15 that health care
providers
concerns should be valued and addresses
immediately.”
ask questions about different aspects
of

development. These questions include (but
are not limited to) those listed here.
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AUTISM OVERVIEW
Does your child…15
Is there a cure for autism?
● Not
To

speak as well as other children
his/her
date, there is no cure for autism, but
sometimes,
age?
children with ASDs make so much
progress that they no longer show the full
● Have
syndrome

poor eye contact?
of autism when they are older.
● Act

as if he/she is in his/her own world?
Research16 shows that early diagnosis and
● Seem
interventions delivered early in life, such as in

to “tune out” others?
the preschool period, are more likely to result in
● Not
major

smile when smiled at?
positive effects on later skills and
symptoms. The sooner a child begins to get
● Seem

unable to tell you what he/she wants,
and
help, the more opportunity for learning. Because
so takes your hand and leads you to what
he/she
a young child’s brain is still forming, early
wants, or gets it him/herself?
intervention gives children the best start possible
and
● Have
the best chance of developing their full

trouble following simple directions?
potential. Even so, no matter when a person is
● Not
diagnosed

play with toys in a usual way?
with autism, it’s never too late to
benefit from treatment. People of all ages with
● Not
ASDs

bring things to you to “show” you
something?
at all levels of ability generally respond

positively to well designed interventions.
● Not

point to interesting things or direct your
attention
Public Law 108­77: Individuals with Disabilities
to items of interest?
17
Education Improvement Act (2004) and Public
● Have
Law 105­17: Individuals with Disabilities Act, or

unusually long or severe temper
tantrums?
18 (1997)

IDEA
require your child’s primary care
provider to refer you and your family to an early
● Show
intervention

an unusual attachment to objects,
especially
service. Every state operates an
“hard” ones, such as a flashlight or
early
key
intervention program for children from
chain, instead of “soft” ones, such as a
birth
blanket
to age three; children with autism should
or stuffed animal?
qualify for these services. Early intervention
programs typically include behavioral methods,
● Prefer

to play alone?
early developmental education, communication
skills,
● Not
occupational and physical therapy, and

pretend or play “make believe” (if the
child
structured social play.
is older than age two)?
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AUTISM RESEARCH AT THE NICHD
Ke p
What are the treatments
in mind that other therapies, beyond ABA,
may
for autism?
also be effective for persons with autism.
Talk to your health care provider about the best
Currently
options for your child.
there is no definitive, single treatment
for ASDs. However, there are a variety of ways
to
A variety of health care providers can also help
help minimize the symptoms and maximize
learning.
individuals with ASDs and their families to work
Persons with an ASD have the best
chance
through different situations.
of using all of their individual capabilities
and skills if they receive appropriate behavioral
and
● Speech­language therapists can help people
other therapies, education, and medication.
In
autism improve their general ability to
some cases, these treatments can help people
with
communicate and interact with others
autism function at near­normal levels.
effectively, as well as develop their speech and
Some
language skills. These therapists may teach
possible treatments for autism are
explained
non­verbal ways of communicating and may
below. If you have a question about
treatment,
improve social skills that involve
you should talk to a health care
provider
communicating with others. They may also
who specializes in caring for people
with
help people to bet er use words and sentences,
autism.
and to improve rate and rhythm of speech and
conversation.
Behavioral therapy and other
●
therapeutic options
Occupational therapists can help people with
In
autism find ways to adjust tasks and conditions
general, behavior management therapy
works
that match their needs and abilities. Such help
to reinforce wanted behaviors and reduce
unwanted
may include finding a specially designed
behaviors. At the same time, these
methods
computer mouse and keyboard to ease
also suggest what caregivers should do
before
communication, or identifying skills that build
or between episodes of problem
behaviors,
on a person’s interests and individual
and what to do during or after these
episodes.
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
applications
physical therapists do (see below).
of ABA commonly used for people
with autism include: Positive Behavioral
Interventions
● Physical therapists design activities and
and Support (PBS), Pivotal
Response
exercises to build motor control and to
Training (PRT), Incidental Teaching,
Milieu
improve posture and balance. For example,
Therapy, Verbal Behavior, and Discrete
Trial
they can help a child who avoids body contact
Teaching (DTT), among others.
to participate in activities and games with other
children.
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AUTISM OVERVIEW
Special services are often available to preschool To
and
qualify for special education services, the
school­aged children, as well as to teens,
child
through
must meet specific criteria as outlined by
the local public school system. In many
federal
cases,
and state guidelines. You can contact a
services provided by specialists in the
local
school
school principal or special education
setting are free. More intense and
coordinator
individualized
to learn how to have your child
help is available through private
assessed
clinics,
to see if he or she qualifies for services
but the family usually has to pay for
under
private
these laws.
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
Educational and/or
other child development specialists, will work
school­based options
together
Children
to design an Individualized
19 for
with ASDs are guaranteed free,
appropriate
Educational Plan (IEP)
your child. An
IEP
public education under federal laws.
includes specific academic, communication,
motor,
Public Law 108­77: Individuals with Disabilities
17
learning, functional, and socialization
goals
Education Improvement Act (2004) and Public
for a child based on his or her educational
needs.
Law 105­17: The Individuals with Disabilities
18
The team also decides how best to carry
out
Education Act—IDEA (1997) make it possible
for
the IEP, such as determining any devices or
special
children with disabilities to get free
educational
assistance the child needs, and identifying
the
services and educational devices to
help
developmental specialists who will work
with
them learn as much as they can. Each child
is
the child.
entitled to these services from age three
through
The
high school, or until age 21, whichever
comes
special services team should evaluate and
re­evaluate
first.
your child on a regular basis to see
how
The
your child is doing and whether any
changes
laws state that children must be taught in
the
are needed in his or her plan.
least restrictive environment, appropriate for
that
A
individual child. This statement does not
mean
number of parents’ organizations, both
national
that each child must be placed in a regular
classroom.
and local, provide information on
therapeutic
Instead, the laws mean that the
teaching
and educational services and how to
get
environment should be designed to
meet
these services for a child. Visit
a child’s learning needs, while minimizing
restrictions
http://www.nlm.nih.gov/medlineplus/autism.html
for
on the child’s access to typical
learning
a listing of these organizations, or check the
local
experiences and interactions. Educating
persons
phone book.
with ASDs often includes a combination
of one­to­one, small group, and regular
classroom instruction.
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AUTISM RESEARCH AT THE NICHD
Medications
Medication options
used to treat the symptoms of
Currently,
autism20 may include (but are not limited to):
there is no medication that can cure
ASDs or all of the associated symptoms.
Further,
● Selective serotonin re­uptake inhibitors (SSRIs)
the Food and Drug Administration
are a group of antidepressants that treat
(FDA) has not approved any drugs specifically
for
problems, such as obsessive­compulsive
the treatment of autism or its causes. But, in
many
behaviors and anxiety, resulting from an
cases, medication can treat some of the
symptoms
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.
Medication
● Tricyclics are another type of antidepressant
can improve the behavior of a
person
used to treat depression and obsessive­
with autism. Health care providers often
use
compulsive behaviors. Although these drugs
medications to deal with a specific behavior,
such
tend to cause more side effects than the SSRIs,
as reducing self­injurious behavior. With
the
sometimes they are more effective for certain
symptom minimized, the person with autism
can
people.
focus on other things, including learning and
communication. Some of these medications
have
● Psychoactive or anti­psychotic medications affect
serious risks involved with their use; others
may
the brain of the person taking them. Use of
make symptoms worse at first or may take
several
this group of drugs is the most widely studied
weeks to become effective.
treatment for autism. In some people with
Not
ASDs, these drugs may decrease hyperactivity,
every medication helps every person with
symptoms
reduce stereotyped behaviors, and minimize
of autism. Health care providers
usually
withdrawal and aggression.
prescribe medications on a trial basis, to
see if it helps. Your child’s health care provider
may
● Stimulants may be useful in increasing focus
have to try different dosages or different
combinations
and decreasing hyperactivity in people with
of medications to find the most
effective
autism, particularly in higher­functioning
plan. Families, caregivers, and health
care
individuals. Because of the risk of side effects,
providers need to work together to make
sure
health care providers should monitor those
that medications are working and that the
overall
using these drugs carefully and often.
medication plan is safe.
● Anti­anxiety drugs can help relieve anxiousness
and panic disorders associated with autism.
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