***
Over the bluff and down La Jolla Shores Drive, Eric Courchesne
(Cor-Shayn), Ph.D., ’75, and his colleagues are having success
with a very different approach.
Courchesne and his colleagues do their work a few blocks from
the beach in a teal and white converted office, with an Excel Fitness
Center and a State Farm Insurance office as neighbors. Though the
building is simple and nondescript, it is home to some of the most
advanced brain scanning equipment at UCSD. Courchesne and his colleagues
study why children become autistic in the first place, what happens
to the brain during those first critical years.
For a long time after the discovery of autism, researchers could
find nothing obviously wrong in the brain that might cause the
disorder. Unlike Alzheimer’s disease or spongiform encephalopathy,
there were no identifiable neural tangles or dead spots in the
brain.
In the mid 1980s, Courchesne’s lab used magnetic resonance
imaging (MRI) to show that the part of the brain called the cerebellum
is underdeveloped in autistic people. The cerebellum, a finely
wrinkled structure that sits behind and below the rest of the brain,
has long been thought to be involved in learned motor skills and
coordination. But Courchesne was one of the first researchers to
show that the cerebellum plays a part in attention, arousal, and
the integration of sensory information—precisely the things
that seem to be lacking in autistic children.
In more recent research, he noticed that autistic children tend
to have larger heads—and brains—than other children.
Children who would later become autistic had heads that were on
average a little smaller than normal at birth, but went through
very rapid brain growth during their first year. By the time they
were diagnosed with autism, these children had average head sizes
in the 85th percentile, which meant that seven out of eight children
had smaller heads than they did.
The study, which he published in 2003 with UCSD researchers Ruth
Carper, ’01, and Natacha Akshoomoff, ’92, was significant.
Unlike other autistic brain findings, these changes actually preceded
the diagnosis of autism. There is a good chance that the overgrowth
of the brain during the first year is a cause, rather than an effect
of the autism.
Courchesne’s working model is that brain growth is supposed
to occur slowly, shaped by the feedback of everyday experience. “Without
the guidance of experience and learning, the brain may be creating
abnormal connections that make it very hard for autistic children
to make sense of the world they live in,” he says.
The autistic brain may be like a garden that turns into a jungle,
because the plants and weeds grow too quickly for the gardener
to keep up.
This idea might also offer an explanation as to why autistic
children withdraw from the world, Courchesne and others say. While
most of us are easily able to block out random noises, sounds and
sights around us, concentrating only on what is important, autistic
children don’t have this ability. Their massively overwired
brains are like giant seine nets, capturing every stimulus in their
environment and becoming unbearably overexcited. Withdrawing, rhythmic
rocking and focusing on inanimate objects may be just some of the
ways that people with autism calm themselves.
Rapid increases in head size might also offer an easy diagnostic
test—one that could help parents catch autism early, when
it is most amenable to treatment. “If pediatricians did head
circumference measurements at each visit through the first year
they might catch an abnormally rapid brain growth and refer the
child for further testing,” Courchesne says.
***
Other researchers at UCSD are studying autism partly for what
it can tell us about the disorder, and partly for what it might
tell us about how the brain normally works. V.S. Ramachandran,
the director of the Center for Brain and Cognition, teamed up with
Jaime Pineda, ’87, director of UCSD’s Cognitive Neuroscience
Laboratory, and Eric Altschuler, Ph.D. ’99, to study what
are called mirror neurons. These neurons, located in the premotor
cortex, fire both when we do an action and when we see others do
the same action. Also called the “monkey see, monkey do” neurons,
they are thought to be involved not only in actions, but also in
higher functions like being able to put yourself in others’ shoes,
to imitate and learn from others’ actions, and intuit others’ intentions.
These neurons are also thought to be involved in language and communication.
These abilities are precisely what autistics are deficient in,
so Ramachandran, Altschuler and Pineda compared the activity of
the mirror neurons in normal and autistic subjects. They found
that although the mirror neurons were active when the autistic
subjects performed an activity, the neurons were silent when the
same subjects observed others performing the same activity.
Ramachandran believes this may be the key difference in autistic
brains, underlying many of the common aspects of autism. He points
out, however, that knowing the neural deficit still doesn’t
explain why the mirror neurons fail to do their job. “It
could be genetics, it could be inflammation, it could be predisposition
to viral infection,” he says. He believes that once we understand
what’s going on in the brain we can, perhaps, treat the cause,
and help the mirror neurons to function normally again.
***
The rapid rise in autism diagnoses has prompted desperate parents,
as well as real and self-appointed “experts,” to identify
various possible reasons for the epidemic, even though it’s
not clear that the number of autistic children has really increased
at all.
“ Part of the rise in diagnosis is the result of increased
awareness, better diagnostic tools, knowing what to look for in
younger children, and better services for autistic children,” Schreibman
says. “I’ve had doctors tell me that if a diagnosis
of autism will get the child more help, and they can squeeze out
that diagnosis, they will.
“ To some extent the rise in autism cases may be real, but
I don’t believe that the rate of autism has really increased
by a factor of 60,” she says.
That hasn’t stopped people from blaming the mercury in
vaccines, environmental toxins, food additives, infections and
various other causes for their children’s condition. Seeking
to bring reason and information to the debate, Schreibman is publishing
a book in November called The Science and Fiction of Autism (see
sidebar, page 20). She understands that parents are angry, scared
and desperate, but she would like them to be able to think critically
about the controversies, to understand a little more about how
science works and how evidence is gathered.
This mission is something Schreibman works on every day. On the
ground floor of McGill Hall, an adorable 2-year-old named Tyler
drapes himself over a chair, happily pressing his cheek against
the vinyl seat. In one of the toy-filled rooms off the main hall,
Schreibman and her colleagues will work with Tyler, encouraging
him to express himself, to interact, to make contact. Just as important,
they will be working with Tyler’s mother, teaching her about
her son’s condition, modeling teaching techniques, lifting
her hopes when they can and tempering her expectations where they
must.
“ You can’t sit out waiting for a miracle pill that
is going to cure everything,” Schreibman says. “All
I can do is offer years of hard work, but it’s what we have,
and it can make a huge difference.”
Christopher Vaughan has written numerous books and articles
on medical topics. He lives in the Bay Area. |
