[Paleopsych] MSNBC: As autism cases soar, a search for clues

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As autism cases soar, a search for clues
http://www.msnbc.msn.com/id/6947652/ et seq.

    Today show
    By Jacqueline Stenson
    Contributing editor
    Updated: 2:58 p.m. ET Feb. 24, 2005

    Once a rare diagnosis, it seems there's now an epidemic of autism
    sweeping the nation. Many of us know a child with the disorder, and
    concerned parents are searching for suspicious signs even in young
    babies. But while more kids are being labeled with autism, whether the
    condition is truly more common among today's children than past
    generations of youngsters is largely unclear.

    There's no question that autism diagnoses are increasing, but it's
    unknown how much of that is due to greater awareness of the disorder
    by doctors and the public, a broader definition of it, a true increase
    in incidence or other factors.

    "There is a chance we're seeing a true rise, but right now I don't
    think anybody can answer that question for sure," says Dr. Chris
    Johnson, a professor of pediatrics at the University of Texas Health
    Sciences Center at San Antonio and co-chair of the American Academy of
    Pediatrics Autism Expert Panel.

    Parents who believe the disorder is increasing due to some modern
    threat that is damaging the brains of children have pointed the finger
    at childhood vaccinations and the mercury-containing preservative
    thimerosal that was once widely used in many of them. There are also
    suspicions about lead or other toxins in the environment, diet,
    viruses and medications. Indeed, some experts say it's possible that
    exposures in utero or in early childhood may play a role.

    Frustrated parents struggling to cope with a disorder that seemed to
    appear virtually overnight understandably want answers. But clear
    insights are hard to come by.

    Cases skyrocketing
    Studies done in the 1960s indicated that autism was quite rare,
    affecting only about one person in every 2,000 to 2,500, according to
    the Centers for Disease Control and Prevention. Other research in 1970
    put the figure at one case per 10,000, Johnson says.

    Precisely how many people have autism today is unknown. But estimates
    suggest there are five to six cases of autism spectrum disorders
    (ASDs) per 1,000 people, says Johnson. That roughly equates to as many
    as one case out of every 166 people.

    It's important to note that today's figures apply to the whole
    category of ASDs, which includes autism as well as related conditions
    like Asperger Syndrome and Pervasive Developmental Disorder Not
    Otherwise Specified. Children with these disorders have varying
    degrees of impaired communication and social interaction.

    Diagnostic criteria changed dramatically in 1987, broadening the
    number of people who could be considered to have ASDs. In decades
    earlier, only those with severe autistic characteristics would be
    diagnosed with autism; others might have been categorized as mentally
    retarded, for example. So making comparisons across decades is

    "The frequency of the diagnosis has clearly increased but that doesn't
    tell you beans," emphasizes Dr. William Barbaresi, a pediatrician at
    the Mayo Clinic in Rochester, Minn.

    To get a better picture of autism and its potential causes, Barbaresi
    and colleagues examined new cases of autism in Olmsted County, Minn.,
    from 1976 to 1997.

    Using data on every child living in the county during those years, the
    researchers used modern diagnostic criteria to conclude that the
    incidence of autism specifically rose dramatically, from 5.5 cases per
    100,000 children from 1980 to 1983, to 44.9 cases from 1995 to 1997.

    A sharp increase started between 1988 and 1991, a period during which
    broader diagnostic criteria for autism were newly in use and increased
    awareness of the disorder occurred, Barbaresi says.


    Other studies also have failed to link vaccinations to autism,
    prompting the Institute of Medicine, an independent group that advises
    the federal government, to conclude there is no connection.

    But no one knows exactly what causes ASDs, and until they do, much
    about these disorders will remain a source of great speculation.

    Many unknowns
    To say that there's a lot doctors don't know about these conditions is
    "an understatement," says Dr. Leonard Rappaport, director of the
    Developmental Medicine Center at Children's Hospital Boston.

    "Most things we don't know," he says.

    Rappaport suspects there may be a true rise in ASDs, though he says
    it's not at all clear why or to what extent.

    To better understand the causes, and hopefully improve diagnosis and
    treatment, Rappaport is involved in a new study that is focusing on
    genetic underpinnings of the disorders that he says may play a role in
    upwards of 90 percent of cases. The federal government also has
    organized an international coalition to explore the genetics.

    Many scientists believe that ASDs are largely caused by genes. Studies
    have shown, for instance, that if one identical twin has autism the
    second twin is very likely to also have the disorder. But the risk
    isn't 100 percent, suggesting that other factors can contribute, even
    if they aren't the main cause.

    "I think it's clear that there's a strong genetic predisposition,"
    says Dr. Steve Sommer, chairman of the department of molecular
    genetics at City of Hope National Medical Center in Duarte, Calif.

    One theory behind a cluster of cases of high-functioning autism and
    Asperger Syndrome in Silicon Valley holds that people who carry the
    genes gravitate toward high-tech professions like computer science
    that don't necessarily require a lot of social interaction. And when
    these people, who may not have the full-blown disorders, meet and have
    children together, the kids could be fully affected because of the
    double genetic whammy from both parents.

    Down the line, scientists suspect they may find many genes involved in

    Sommer's research has shown that a mutation in the neuroligin 4 gene,
    which is involved in creating healthy connections between neurons in
    the brain, is defective in about 3 percent of people with autism. But
    that doesn't mean that everyone who inherits the defective gene will
    develop autism, he says. And there are likely many more genes that
    play a role in the condition in certain people.

    "From a genetic point of view, autism is likely to be many -- perhaps
    a hundred or more -- diseases," he says.

    Sleepless nights
    But if autism spectrum disorders are truly on the rise, genes aren't
    the reason. "The gene pool doesn't change," explains Rappaport. "It
    would have to be something that's environmental."

    That something -- if it does exist -- remains a huge mystery and a
    source of endless worry for parents, especially given that there is
    currently no known way to prevent autism.

    Rappaport says many parents fear they may have done something to
    trigger the problem, like taking their kids to get regularly scheduled
    immunizations or exposing themselves to environmental toxins.

    "Parents are searching for answers, and they're blaming themselves for
    a million different things," he says.

    "I can't even imagine all the sleepless nights."

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