Autism is not a disease,
but a developmental disorder of brain function.
People with classical autism show three types of symptoms: impaired
social interaction, problems with verbal and nonverbal communication,
and unusual or severely limited activities and interests. Symptoms of
autism usually appear during the first three years of childhood and
continue throughout life. These symptoms can vary in severity. In
addition, people with autism often have abnormal responses to sounds,
touch, or other sensory stimulation. Although there is no cure,
appropriate early educational intervention may improve social
development and reduce undesirable behaviors. People with autism have
a normal life expectancy.
Autism affects
an estimated 10 to 20 of every 10,000 people, depending on the
diagnostic criteria used. Most estimates that include people with
similar disorders are two to three times greater. Autism strikes males
about four times as often as females, and has been found throughout
the world in people of all racial and social backgrounds. Recent
studies strongly suggest that some people have a genetic
predisposition to autism. Researchers are looking for clues about
which genes contribute to this increased susceptibility. In some
children, environmental factors also may play a role. Studies of
people with autism have found abnormalities in several regions of the
brain which suggest that autism results from a disruption of early
fetal brain development.
Autism varies a
great deal in severity. The most severe cases are marked by extremely
repetitive, unusual, self-injurious, and aggressive behavior. This
behavior may persist over time and prove very difficult to change,
posing a tremendous challenge to those who must live with, treat, and
teach these individuals. The mildest forms of autism resemble a
personality disorder associated with a perceived learning disability.
The hallmark
feature of autism is impaired social interaction. Children with autism
may fail to respond to their names and often avoid looking at other
people. They often have difficulty interpreting tone of voice or
facial expressions and do not respond to others' emotions or watch
other people's faces for cues about appropriate behavior. They appear
unaware of others' feelings toward them and of the negative impact of
their behavior on other people.
Many children
with autism engage in repetitive movements such as rocking and hair
twirling, or in self-injurious 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."
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.
People with
autism often have abnormal responses to sounds, touch, or other
sensory stimulation. Many show reduced sensitivity to pain. They also
may be extraordinarily sensitive to other sensations. These unusual
sensitivities may contribute to behavioral symptoms such as resistance
to being cuddled.
Autism is
classified as one of the pervasive developmental disorders. Some
doctors also use terms such as "emotionally disturbed" to describe
people with autism. Because it varies widely in its severity and
symptoms, autism may go unrecognized, especially in mildly affected
individuals or in those with multiple handicaps. Researchers and
therapists have developed several sets of diagnostic criteria for
autism. Some frequently used criteria include:*
• Absence or
impairment of imaginative and social play
• Impaired
ability to make friends with peers
• Impaired
ability to initiate or sustain a conversation with others
• Stereotyped,
repetitive, or unusual use of language
• Restricted
patterns of interests that are abnormal in intensity or focus
• Apparently
inflexible adherence to specific routines or rituals
• Preoccupation with parts of objects
Children with
some symptoms of autism, but not enough to be diagnosed with the
classical form of the disorder, are often diagnosed with pervasive
developmental disorder - not otherwise specified (PDD - NOS). People
with autistic behavior but well-developed language skills are often
diagnosed with Asperger syndrome. Children who appear normal in their
first several years, then lose skills and begin showing autistic
behavior, may be diagnosed with childhood disintegrative disorder (CDD).
Girls with Rett syndrome, a sex-linked genetic disorder characterized
by inadequate brain growth, seizures, and other neurological problems,
also may show autistic behavior. PDD - NOS, Asperger syndrome, CDD,
and Rett syndrome are referred to as autism spectrum disorders.
Since hearing
problems can be confused with autism, children with delayed speech
development should always have their hearing checked. Children
sometimes have impaired hearing in addition to autism. About half of
people with autism score below 50 on IQ tests, 20 percent score
between 50 and 70, and 30 percent score higher than 70. However,
estimating IQ in young children with autism is often difficult because
problems with language and behavior can interfere with testing. A
small percentage of people with autism are savants. These people have
limited but extraordinary skills in areas like music, mathematics,
drawing, or visualization.
Autism has no
single cause. Researchers have identified a number of genes that play
a role in the disorder. In some children, environmental factors also
may play a role in development of the disorder. Studies of people with
autism have found abnormalities in several regions of the brain,
including the cerebellum, amygdala, hippocampus, septum, and mamillary
bodies. Neurons in these regions appear smaller than normal and have
stunted nerve fibers, which may interfere with nerve signaling. These
abnormalities suggest that autism results from disruption of normal
brain development early in fetal development. Other studies suggest
that people with autism have abnormalities of serotonin or other
signaling molecules in the brain. While these findings are intriguing,
they are preliminary and require further study. The early belief that
parental practices are responsible for autism has now been disproved.
In a minority
of cases, disorders such as fragile X syndrome, tuberous sclerosis,
untreated phenylketonuria (PKU), and congenital rubella cause autistic
behavior. Other disorders, including Tourette syndrome, learning
disabilities, and attention deficit disorder, often occur with autism
but do not cause it. While people with schizophrenia may show some
autistic-like behavior, their symptoms usually do not appear until the
late teens or early adulthood. Most people with schizophrenia also
have hallucinations and delusions, which are not found in autism.
Recent studies
strongly suggest that some people have a genetic predisposition to
autism. Scientists estimate that, in families with one autistic child,
the risk of having a second child with the disorder is approximately
five percent, or one in 20, which is greater than the risk for the
general population (see "What is autism?"). Researchers are looking
for clues about which genes contribute to this increased
susceptibility. In some cases, parents and other relatives of an
autistic person show mild social, communicative, or repetitive
behaviors that allow them to function normally but appear linked to
autism. Evidence also suggests that some affective, or emotional,
disorders occur more frequently than average in families of people
with autism.
Symptoms in
many children with autism improve with intervention or as the children
mature. Some people with autism eventually lead normal or near-normal
lives. About a third of children with autistic spectrum disorders
eventually develop epilepsy. The risk is highest in children with
severe cognitive impairment and motor deficits. Adolescence may worsen
behavior problems in some children with autism, who may become
depressed or increasingly unmanageable. Parents should be ready to
adjust treatment for their child's changing needs.
There is no
cure for autism at present. Therapies, or interventions, are designed
to remedy specific symptoms in each individual. The best-studied
therapies include educational/behavioral and medical interventions.
Although these interventions do not cure autism, they often bring
about substantial improvement.
Appropriate treatment may foster relatively normal development and reduce
undesirable behaviors. Educational/behavioral therapies and drug
interventions are designed to remedy specific symptoms.
Educational/behavioral therapies emphasize highly structured and often
intensive skill-oriented training. Doctors also may prescribe a
variety of drugs to reduce symptoms of autism. Other interventions
are available, but few, if any, scientific studies support their use.
Educational/behavioral interventions:
These strategies emphasize highly structured and often intensive
skill-oriented training that is tailored to the individual child.
Therapists work with children to help them develop social and language
skills. Because children learn most effectively and rapidly when very
young, this type of therapy should begin as early as possible. Recent
evidence suggests that early intervention has a good chance of
favorably influencing brain development.
Medication:
Doctors may prescribe a variety of drugs to reduce self-injurious
behavior or other troublesome symptoms of autism, as well as
associated conditions such as epilepsy and attention disorders. Most
of these drugs affect levels of serotonin or other signaling chemicals
in the brain.
Many other
interventions are available, but few, if any, scientific studies
support their use. These therapies remain controversial and may or may
not reduce a specific person's symptoms. Parents should use caution
before subscribing to any particular treatment. Counseling for the
families of people with autism also may assist them in coping with the
disorder.
People with
autism have normal life expectancies. Symptoms in many children
improve with intervention or as the children age. Some people with
autism eventually lead normal or near-normal lives. Adolescence can
worsen behavior problems in some children, and parents should be ready
to adjust treatment for the child's changing needs. About a third of
children with autistic spectrum disorders eventually develop epilepsy.
The risk is highest in children with severe cognitive impairment and
motor deficits.
Research
includes studies aimed at identifying the underlying brain
abnormalities of autism through new methods of brain imaging and other
innovative techniques. Researchers also are investigating possible
biologic markers present at birth that can identify infants at risk
for the development of autism. Some scientists hope to identify genes
that increase the risk of autism. Others are studying specific aspects
of behavior, information processing, and other characteristics to
learn precisely how children with autism differ from other people and
how these characteristics change over time. The findings may lead to
improved strategies for early diagnosis and intervention. Related
studies are examining how the cerebellum develops and processes
information, how different brain regions function in relation to each
other, and how alterations in this relationship during development may
result in the signs and symptoms of autism. Researchers hope this
research will provide new clues about how autism develops and how
brain abnormalities affect behavior.
Other studies are
aimed at identifying the underlying brain abnormalities of autism
through new methods of brain imaging and other innovative techniques,
and at identifying genes that increase the risk of autism. Researchers
also are investigating possible biologic markers present at birth that
can identify infants at risk for the development of autism. Other
studies are examining how different brain regions develop and function
in relation to each other, and how alterations in these relationships
may result in the signs and symptoms of autism. Researchers hope these
studies will provide new clues about how autism develops and how brain
abnormalities affect behavior.
(The above compilation was prepared by
Steven Merahn, MD, Chief Medical Officer of Medalis, Inc., located
in Philadelphia. Dr. Merahn produced this compilation through
materials developed at the National Institutes of Health. Dr.
Merahn generously granted permission for use of this compilation.)