Autism Birth Cohort Study

“The frequency of this disorder is likely to be increasing … it’s an area that has deserved a great deal more emphasis than it has had for a long time,” said Dr. Ian Lipkin, director of the Autism Birth Cohort and a professor at the School of Public Health.

The Cohort is a broad-based epidemiological study that uses new
technology to identify how genetics, environment, and timing combine to
cause autism.

A government attempt to free chemical companies from liability for
chemicals linked to autism inadvertently attracted major publicity.

Preliminary research indicated a relationship between prenatal and infant
exposure to thimerosal, present in several vaccines, and autism. In
November 2002 an unknown senator embedded deep within a 475-page homeland security bill a provision removing the liability of manufacturers of thimerosal.

While the ensuing scandal caused the provision to be scrapped in January 2002, thimerosal’s relationship to autism remains unclear.

“People just want this issue to go away,” said Dr. Mady Hornig, an
associate professor of epidemiology whose research corroborates the
connection between autism and thimerosal. She also works with the Autism
Birth Cohort.

Thimerosal is one of the many possible toxic and infectious agents whose effects the Autism Birth Cohort will examine. The Cohort will follow over 75,000 Norwegian expectant mothers and their children, analyzing their medical records, blood samples, and survey questionnaires in order to
trace specific agents to the onset of the disease.

New technology will allow for intensified study into gene expression
of study participants. Hornig said that one of the most revolutionary
aspects of the Autism Birth Cohort is its access to funds to buy a certain
type of test tube.

“I know that sounds very trivial, but this is basically the turning
point that turns this birth cohort into one that is unique in the world,”
she said, because the test tubes allow for the collection of the genetic
material RNA.

Early DNA collection is nothing revolutionary because an
individual’s DNA remains constant throughout their lifetime. According to Hornig, RNA differs because it “tells you which genes are turned on and off at a particular point in time … [and provides a] look at gene expression at a
particular point in time.”

Hornig’s research with mice helped demonstrate a link between
thimerosal and autism worth pursuing in the Autism Birth Cohort.

Research on mice is less complex than on humans for many reasons,
including the presence of a specific gene group, H-2S, which can cause
autism-like behavior in mice. In humans no specific genes indicating a
predisposition to autism have been identified.

Finding a conclusive single specific cause of autism is extremely unlikely despite Hornig’s initial findings about thimerosal.

“We think it is unlikely to be a singular environmental factor” that causes autism, Hornig said. Autism itself is understood to be a spectrum of disorders, increasing the “difficulty in teasing out this complexity.”

Despite the lack of a definite link, Hornig’s findings in mice have caused her to question the use of thimerosal in vaccines. Thimerosal is not actually a necessary component of vaccines: it serves only as an anti-microbial preservative for multi-dose vials. Today it is largely found in flu shots and older vaccinations.

“There is no legitimate reason other than cost” to use this additive, Hornig said, adding that at an additional cost of approximately four dollars a vial manufacturers could simply produce single-dose packages and eliminate thimerosal entirely.

The issue is hotly political, however, and it is unlikely policy and health officials will reach a consensus on thimerosal in the near future. Rejecting research like Hornig’s, the Center for Disease Control Web site states, “No harmful effects have been reported from thimerosal at doses used in vaccines, except for minor reactions like redness or swelling at the reaction site.”

Despite the clarity of their conclusions, the CDC does say no vaccines used on preschool children against infectious diseases contain thimerosal.

This is significant because children generally begin exhibiting signs of
autism between the ages of 12 and 15 months. Prenatal exposure to
different triggers like thimerosal is a major focus of autism research.
In looking to further study the possible effects of thimerosal, the Autism Birth Cohort will focus its research on the prenatal and infancy stages of development. The project, however, will continue for the long term, which Lipkin hopes will allow researches studying other chronic diseases such as asthma, diabetes, and schizophrenia to be able to use the data as well.

“This is the Autism Birth Cohort project, but it’s really much, much
more. It’s the paradigm for any sort of efforts to investigate” the normal
trajectory of disease, Lipkin said.