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By Stacy Tibbetts
Research/Penn State
Dustin Hoffman's memorable portrayal of an autistic savant
in the 1988 movie "Rain Man" brought unprecedented public
attention to the much misunderstood condition of autism. Hoffman's
character, Raymond Babbitt, is terrified of communicating
with other people, stammers when he speaks and doesn't understand
money, yet can perform complex mathematical calculations in
his head and recite obscure baseball statistics from memory.
Autism is a neurological disorder that typically is diagnosed
within the first three years of life, when affected children
fail to meet normal developmental milestones, particularly
in areas of language and socialization. The word autism derives
from the Greek word "autos," or "self," and refers to the
often withdrawn and self-focused perspective people with the
disorder appear to have. Four times more likely to occur in
boys than in girls, autism is considered an incurable condition
with an unknown cause.
Though autism encompasses a wide range of symptoms with varying
severity, autistic people generally share a difficulty connecting
emotionally to others, communicating verbally, and interpreting
non-verbal communication, such as facial expressions and gestures.
Like the character in "Rain Man," those with autism often
find any change in routine very disturbing and are prone to
repetitive movements, such as rocking or spinning. However,
unlike Dustin Hoffman's character, high I.Q. savants (with
extraordinary memories and computing abilities) are extremely
rare. The majority of autistic people have some degree of
mental retardation.
Public interest in autism is on the rise, as new diagnoses
have skyrocketed. (One well-known longitudinal study in Minnesota
schoolchildren concluded that the incidence of autism rose
from 5.5 cases per 100,000 children from 1980 to 1983, to
44.9 cases from 1995 to 1997.) Estimates vary, but today as
many as 1 in 166 children are diagnosed with autism or related
disorders, and about 1 in 500 to 1,000 people live with the
disability.
The spike in diagnoses has many seeking answers. A Penn State
conference on the subject in August drew more than 2,000 attendees.
One question on the minds of parents and professionals is
"What has caused this sharp increase?"
Some controversial studies have claimed that overexposure
to mercury in the form of thimerosal, a preservative used
in children's immunizations, is a likely culprit. During the
1990s, the Centers for Disease Control expanded the number
of thimerosal-containing vaccines on the infant immunization
schedule. According to some anti-thimerosal activists, some
vaccinated children may have been exposed to 125 times the
federal limit for mercury exposure.
Another intriguing line of inquiry concerns "mirror neurons,"
which Italian researchers recently discovered in the brains
of chimpanzees. Their hypothesis is that these specialized
neurons enable us to understand the actions and emotions of
others by replicating their states in our own brains. This
neurological "aping" bypasses conceptual reasoning as a means
of comprehension and relies instead on an internal, experiential
knowledge of others. If, as some believe, the mirror neuron
system is impaired in autistic individuals, it might explain
their characteristic inability to identify and empathize with
others.
"Studies of twins have indicated a strong genetic predisposition
to the disability," said Pamela Wolfe, associate professor
of special education at Penn State. "If one twin has autism,
the other is highly likely to have it as well. But I think
it's caused by a combination of genetic predisposition and
environmental factors." Wolfe attributed the apparent increase
in cases to a broadening of diagnostic criteria, which occurred
in the late 1980s. "We've seen significant improvements in
diagnosis techniques over the last few years,"she said. "Previous
autistic tendencies that might have gone undiagnosed now may
fall under that heading." Autism spectrum disorders, as they're
known in the profession, have grown to include mild forms
like Asperger's Syndrome as well as partial diagnoses like
PDD-NOS, which stands for "pervasive developmental disorder,
not otherwise specified."
Earlier diagnoses also contribute to the trend. Rebecca Landa,
the director of the Center for Autism and Related Disorders,
recently completed an early-detection study for siblings of
autistic children, with the goal of diagnosing and treating
children well before their third birthdays. "Landa's studies
have helped professionals understand the effects of autism
in younger and younger subjects," Wolfe noted. "This heightened
awareness refines our diagnostic abilities and enables us
to pinpoint the disorder more readily." Still, Wolfe suggested
that more long-term studies, which are difficult to conduct,
are needed to determine the root causes of autism. "Diagnoses
are quite complex and difficult, and mental retardation often
accompanies autism. Parents focus on the 'autism' label, because
it's preferable to the stigma of having a retarded child,
one who is simply developmentally delayed."
Wolfe currently teaches in Penn State's award-winning training
program for professionals involved in autism diagnosis. This
program, attended by school counselors, therapists and speech-language
pathologists among others, emphasizes applied behavioral analysis
to diagnose and treat early-childhood illness, and prepares
participants for a national certification examination in the
subject.
Parents seeking more information about autism and related
disorders may want to consult the Autism Encyclopedia, co-authored
by Wolfe and Penn State professor emeritus John Neisworth,
which defines terms and provides explanations of many aspects
of this complex condition.
Pamela S. Wolfe is associate professor of
special education. She can be reached at psw7@psu.edu. For
more Probing Questions, and other features about research
at Penn State, subscribe to Research/Penn State at http://www.rps.psu.edu/subscribe/
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