Autism: Getting to Know a Baffling Disorder
by Michael J. Dochniak
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.
What is autism? Autism
is a complex neurobiological disorder of development that lasts
throughout a person’s life. It is sometimes
called a developmental disability because it usually starts before
age three, in the developmental period, and because it causes delays
or problems in many different skills that arise from infancy to adulthood.
The main signs and symptoms of autism involve language, social behavior,
and behaviors concerning objects and routines:
• Communication—both verbal (spoken) and nonverbal (unspoken,
such as pointing, eye contact, or smiling)
• Social interactions—such as sharing emotions, understanding
how others think and feel (sometimes called empathy), and holding a
conversation, as well as the amount of time a person spends interacting
with others
• Routines or repetitive behaviors—often called stereotyped
behaviors, such as repeating words or actions, obsessively following
routines or schedules, playing with toys or objects in repetitive and
sometimes inappropriate ways, or having very specific and inflexible
ways of arranging items
People with autism might have problems talking with you, or they
might not look you in the eye when you talk to them. They may have
to line up their pencils before they can pay attention, or they may
say the same sentence again and again to calm themselves down. They
may flap their arms to tell you they are happy, or they might hurt
themselves to tell you they are not. Some people with autism never
learn how to talk. These behaviors not only make life challenging
for people who have autism, but also take a toll on their families,
their health care providers, their teachers, and anyone who comes
in contact with them. Because different people with autism can have
very different features or symptoms, health care providers think
of autism as a “spectrum” disorder—a group of disorders
with a range of similar features. Based on their specific strengths
and weaknesses, people with autism spectrum disorders (ASDs) may
have mild symptoms or more serious symptoms, but they all have an
ASD. This fact sheet uses the terms “ASD” and “autism” to
mean the same thing.
What conditions are in the ASD category? Currently, the ASD category
includes:
• Autistic disorder (also called “classic” autism)
• Asperger syndrome
• Pervasive Developmental Disorder Not Otherwise Specified (or
atypical autism)
In some cases, health
care providers use a broader term—pervasive
developmental disorders (PDD)—to describe autism. The PDD category
includes the ASDs mentioned above and: Childhood disintegrative disorder,
and Rett syndrome.
Depending on specific
symptoms, a person with autism may fall into the ASD or the PDD
category. Sometimes, the terms “ASD” and “PDD” are
used to mean the same thing because autism is in both categories.
What causes autism?
Scientists don’t know exactly what causes
autism at this time. Much evidence supports the idea that genetic
factors—that is, genes, their function, and their interactions—are
one of the main underlying causes of ASDs. But, researchers aren’t
looking for just one gene. Current evidence suggests that as many
as 10 or more genes on different chromosomes may be involved in autism,
to different degrees. Some genes may place a person at greater risk
for autism, called susceptibility. Other genes may cause specific
symptoms or determine how severe those symptoms are. Or, genes with
changes or mutations might add to the symptoms of autism because
the genes or gene products aren’t working properly. Research
has also shown that environmental factors, such as viruses, may also
play a role in causing autism. While some researchers are examining
genes and environmental factors, other researchers are looking at
possible neurological, infectious, metabolic, and immunologic factors
that may be involved in autism. Because the disorder is so complex,
and because no two people with autism are exactly alike, autism is
probably the result of many causes.
How many people have
autism? Currently, researchers don’t
know the exact number of people with an ASD in the United States.
Researchers use different ways to determine prevalence that often
give different results. Some estimates of prevalence rely on previously
published studies. Researchers review all the published data on a
topic and take the averages of these calculations to determine prevalence.
Independent researchers recently conducted two such reviews. Based
on these studies, the best conservative estimate of the prevalence
of ASDs in the United States is that one child in 1,000 children
has an ASD.
Is autism more common now than it was in the past? Researchers are
not certain whether autism is more prevalent now than in the past
for a number 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 more accurate
diagnoses of autism. The new definition of autism as a spectrum disorder
means that even people with mild symptoms can be classified as having
an ASD, which could also account for the increase in identified cases.
As research moves forward using the current definition of ASDs, more
definite numbers may be available to answer this question. n
The above info was taken from
Autism Overview: What We Know at the National Institute of Child
Health and Human Development, www.nichd.nih.gov/publications
