ATLANTA
(AP) -- More than $1 billion has been
spent over the past decade researching autism. In some ways, the search for its
causes looks like a long-running fishing expedition, with a focus on everything
from genetics to the age of the father, the weight of the mother, and how close
a child lives to a freeway.
That
perception may soon change. Some in the field say they are seeing the beginning
of a wave of scientific reports that should strengthen some theories, jettison
others and perhaps even herald new drugs.
"I
do think over the next three to five years we'll be able to paint a much
clearer picture of how genes and environmental factors combine" to cause
autism, said Geraldine Dawson, a psychologist who is chief science officer for
the advocacy group Autism Speaks.
The
effort has been infused with new urgency by a recent federal report that found
autism disorders are far more common than was previously understood, affecting
1 in 88 U.S. children. Better diagnosis is largely responsible for the new
estimate, but health officials said there may actually be more cases of autism,
too.
If
autism's causes remain a mystery, "you're not going to be able to stop
this increase," said Irva Hertz-Picciotto, a researcher at the University
of California, Davis who is leading a closely watched study into what sparks
autism disorders.
In the
past week, a spate of studies released during National Autism Awareness Month
has offered tantalizing new information about potential causes. Research
published in the journal Nature widened the understanding of the genetic roots
of some cases and confirmed the elevated risks for children with older fathers.
Another study, released online Monday in Pediatrics, suggested maternal obesity
may play a role.
To be
sure, finding the causes of autism - an umbrella term for a variety of
disorders that delay children socially or intellectually - remains daunting.
The causes are believed to be complicated, and not necessarily the same for
each child. Some liken autism to cancer - a small word for a wide range of
illnesses. In many cases, autism can be blamed on both genetic problems that
load the gun and other factors that pull the trigger.
It has
been a growing public concern for two decades, as studies have found it to be
more and more prevalent. The U.S. government dramatically increased funding for
autism research in the last decade, and now budgets about $170 million a year
through the National Institutes of Health. That's only about a quarter of what
NIH will spend on breast cancer research and $50 million less than what it will
spend on asthma.
But
more than a half-dozen foundations and autism advocacy groups have been adding
to the pot, putting annual research spending in recent years at more than $300
million. About a third of that has been devoted to finding autism's causes.
The
lion's share of money for finding a cause has been spent on genetics, which so
far experts believe can account for roughly 20 percent of cases. The earliest
success was in the early 1990s and involved the discovery of the genetic
underpinnings of Fragile X syndrome, a rare condition that accounts for just 2
to 4 percent of autism cases but is the most common form of inherited
intellectual disability in boys.
The
focus on genetics has been bolstered by dramatic improvements in gene mapping
as well as the bioengineering of mice with autism symptoms. Dozens of risk
genes have been identified, and a half-dozen drug companies are said to be
working on developing new treatments.
"We've
made some very significant progress on the genetics end of this search,"
said Dr. Thomas Insel, director of the National Institute of Mental Health.
Scientists
have used autistic mice to test new drugs. Among the most promising is a small,
white, strawberry-flavored pill that is so experimental it doesn't have a name.
Developed by a Massachusetts company called Seaside Therapeutics Inc., the drug
is aimed at a problem area in the brains of autistic children, where neurons
connect and conduct signals through the nervous system.
It's a
bit like the way tree-hopping ants might cross the twig ends of one tree branch
to another. In Fragile X syndrome, scientists have noted the branches are
thinner and the twigs too numerous. The experimental drug thins the twigs and
strengthens the branches, allowing a more solid and centralized bridge.
The
same problem hasn't been as visible in other types of autism, but many believe
the phenomenon is somewhat similar.
The
drug was deemed successful in mice and is now being tested in children and
adults. In small, early studies, the drug made a striking difference in small
groups of Fragile X children, causing hermit-like youngsters to start hanging
out in the kitchen to chat with their mothers, said Dr. Paul Wang, Seaside's vice
president of clinical development.
Now it
is being tried in a preliminary study of about 150 children with a range of
other autism disorders, including Asperger's. The results are expected to be
presented at a scientific conference in the next year.
"It's
going to be an exciting time, we hope," when those results come in, said
Dawson, from Autism Speaks.
But
even genetics enthusiasts acknowledge that genes are only part of the answer.
Studies of identical twins have shown that autism can occur in one and not the
other, meaning something outside a child's DNA is triggering the disorder in
many cases. Some cases may be entirely due to other causes, Dawson said.
That
broad "other" category means "environmental" influences -
not necessarily chemicals, but a grab bag of outside factors that include
things like the age of the father at conception and illnesses and medications
the mother had while pregnant.
For
years, the best-known environmental theory involved childhood vaccines,
prompted by a flawed 1998 British study that has been thoroughly discredited.
Dozens of later studies have found no link between vaccines and autism.
But
there are other possible candidates. In all cases, these are
"association" studies - they don't prove cause and effect. They
merely find connections between certain factors and autism. And sometimes these
conclusions can be skewed by other things researchers failed to account for.
Some study results expected within a year:
-
Hertz-Picciotto's
study of 1,600 children in Northern California is comparing autistic children,
youngsters with other developmental disabilities, and those who have no such
diagnoses. Some results have been released already, including the recent
finding that suggests a link between autism and a mother's obesity. An earlier
part of the study found that children born to mothers living less than two
blocks from a freeway were twice as likely to have autism - presumably because
of auto exhaust and air pollution, the researchers speculated.
-
A
Centers for Disease Control and Prevention study involves 2,700 families
nationwide. The researchers are interviewing parents and poring over medical
records to look for common threads among autistic families, as well as doing
genetics tests and checking hair samples for mercury. Much of the focus is on
illnesses, medications, nutritional deficiencies or other problems during
pregnancy.
-
A
study by Pennsylvania researchers involves 1,700 families in various regions of
the country. Scientists are doing brain-imaging to look for changes over time
in the brains of infants who have an older autistic sibling.
-
A
large Scandinavian study is examining patient registries in six countries for
prenatal risk factors.
As
study findings are reported, researchers are hoping to see repetition -
confirmation, that is - that certain factors are playing significant roles.
Even
so, scientists are still casting nets.
Said
Coleen Boyle, a CDC official overseeing research into children's developmental
disabilities: "We're at the infancy of just understanding how these
factors relate to autism."
MIKE
STOBBE
AP
Online:
CDC
study under way: http://www.cdc.gov/ncbddd/autism/seed.html
Northern
California study: http://beincharge.ucdavis.edu
Pennsylvania
researchers' study: http://www.earlistudy.org
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