Scientists Collaborate On Autism

Nearly 400 of the world’s top autism researchers gathered in
Sacramento on Friday for the third annual International Meeting for Autism
Research.

The gathering, sponsored by the National Institutes for Health, the
M.I.N.D. Institute at UC Davis, Cure Autism Now and the National Alliance
for Autism Research, concludes today.

By expanding their knowledge of how infant brains develop, scientists
seek to solve one of the biggest puzzles surrounding the autism explosion:
Why do many parents report that their children develop normally, then
suddenly regress at about 18 months or 2 years? Dr. Steve Dager, a
researcher at the University of Washington, said his team found that at age
3 or 4, autistic children have larger cerebral brain volumes than their
counterparts.

The cerebrum consists of dense, convoluted masses of tissue. The outer
layer is the cerebral cortex or gray matter. In adults, the cortex contains
most of the nerve cells in the nervous system.

“What we’re finding is that by age 6, this kind of interesting
over-growth of the brain or larger brain is no longer apparent,” Dager said.
Kimberley McAllister of the Center for Neuroscience at UC Davis has
focused on uncovering growth patterns in the cerebral cortex during the
first two years of life. She has zeroed in on synapses, or the point at
which an electrical impulse passes from one nerve cell to another.

“The development of these synapses is incredibly critical for proper
functioning of the brain,” she said, noting that it is where information
processing takes place. Her lab is looking at the core components of
synapses, including the hundreds of proteins involved.

Because the formation of synapses occur at about the time autistic
symptoms emerge in many children, “we believe that something about this
process of cellular growth is part of what is causing autism,” she said.
Several other researchers recently published papers suggesting that
abnormalities in a protein known as neuroligin, which plays a role in
forming synapses, may be a factor leading to autism, McAllister said.

While some scientists focus on brain development, others search for
clues in the unusual behavior of autistic children, who often engage in
repetitive activities such as hand flapping, rocking, lining up Lego bricks,
adhering to rituals and becoming upset with change.

It is one of the most understudied fields of autism, said one leading
expert on repetitive behavior.

“Somehow, (autistic) individuals are using these behaviors to order
their environment,” said Mark Lewis, a behavioral scientist at the McKnight
Brain Institute at the University of Florida. Yet little is known about why
they are drawn to such activities.

Experiments with mice shed some light, however. Using drugs,
scientists interrupted the circuitry in mice’s basal ganglia, an area of the
brain that helps the cortex prioritize information. That affected the
animals’ repeated jumping, backflips and other repetitive behavior.

Research on the brain and behavior may reveal what leads to autism,
but it leaves unanswered the question of what triggers it.

Most researchers believe genetics play a role. But others wonder
whether an environmental factor, such as exposure to a toxic material or a
reaction to a vaccine, may push genetically vulnerable children over the
edge into autism.

Many children make progress with early intervention, but there is no
cure. Scientists have scrambled for answers because of a rapid rise in the
number of autistic children throughout the United States, England, Scotland
and other countries. The disorder takes an emotional toll on families and
burdens governments with costly services.

“Each one of these meetings gives us new opportunities to learn about
autism and to build a more complete foundation from which to work,” said
conference chairwoman Sally Rogers in her welcoming letter.
“We will come to understand this disorder based on our collective
knowledge, not any one person’s knowledge.