Story

Study links vaccine to autism
Others doubt findings: U.S. researcher calls preservative used in annual
flu shot a 'smoking gun'

Sharon Kirkey
CanWest News Service


Thursday, February 05, 2004
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OTTAWA - Scientists have found what they believe could be a "smoking
gun" linking additives in vaccines to autism and attention-deficit
hyperactivity disorder in children.

In a study that was rushed to print online today, two months ahead of
its scheduled publication in the journal Molecular Psychiatry, U.S.
researchers have discovered an apparent link between thimerosal, a
controversial mercury-based preservative once commonly used in childhood
vaccines, to an increased risk of neurological disorders such as autism
and ADHD.

While most vaccines distributed in Canada have been thimerosal-free
since the early 1960s, the preservative was used in the annual flu shot
that doctors recommended this year for even healthy children.

In tests on human brain cells, researchers found two natural chemicals
-- one compound that stimulates cell growth and also dopamine, which
transmits nerve signals -- are key to a process in the brain called
methylation. Methylation helps DNA work properly and is crucial to the
normal development of the brain.

The team found thimerosal, ethanol and the metals lead and mercury all
interfere with methylation. What's more, thimerosal not only did so in
amounts typically found after a child is vaccinated, but even at doses
100 times lower than a child would receive after a single shot with a
thimerosal-containing vaccine.

"It was by far the most potent," said investigator Dr. Richard Deth, a
professor of pharmacology at Northeastern University in Boston.

"Some would consider [thimerosal] a smoking gun," Dr. Deth said. "I
think it is."

"I don't want to impair the public health importance of vaccine
programs. It's not the vaccines that are the problem, it's the additives
that are the problems."

He said the study, which also involved researchers from Johns Hopkins
University, the University of Nebraska and Tufts University in Boston,
could account for the rising rates of autism since the early 1980s, when
more thimerosal-containing shots were added to a child's vaccine
schedule.

A recent review of vaccine-related "adverse events" in the United States
found a "significant correlation" between shots containing thimerosal
and autism, the researchers report.

In a press release, the journal said the new study is "the first to
offer an explanation for possible causes of two increasingly common
childhood neurological disorders."

But one of Canada's leading experts in vaccination says large studies
have repeatedly failed to find any association between brain damage and
vaccines that do, or do not, contain thimerosal.

"What [the researchers] are doing in the test tube may or may not have
any relationship to what happens in the body," added Dr. Ronald Gold,
professor emeritus of pediatrics at the University of Toronto and author
of Your Child's Best Shot: A Parent's Guide to Vaccination. He says
there is no evidence that the low doses of thimerosal researchers tested
would even cross a child's blood-brain barrier.

But Dr. Deth thinks there may be a link, and he believes thimerosal may
play a role for the one out of 200 children who will experience some
kind of developmental disorder.

Before the early '90s, most causes of autism were believed to have a
strong genetic component, and symptoms surfaced soon after the child was
born.

But a newer, and more common, form of the disease is known as regressive
autism, in which children appear to be developing normally, but then
suddenly regress. "They lose functions they had before, such as early
speech," Dr. Deth says. "Parental anecdotes and clinical reports have
suggested it happened during periods of high vaccine exposure."

"Up to now, people have said the cause, or causes of autism, are
unknown. Our work isn't final in any sense at all, but it seems to point
to this biochemistry as a potential, or even primary cause, of autism."

Thimerosal had been used to prevent the growth of bacteria or fungi in
multi-dose units of vaccines for diseases such as hepatitis and
diphtheria, pertussis (whooping cough) and tetanus, or DPT.

Ontario, Nova Scotia, Newfoundland and P.E.I have not used childhood
vaccines containing thimerosal since the early 1960s, when the provinces
switched to a DPT vaccine that was combined with the killed polio
vaccine. (Thimerosal could not be used with the combined shot because it
destroyed the efficacy of the polio vaccine.) All other provinces began
to move to thimerosal-free vaccines starting in 1997. As of March, 2001,
all vaccines for routine immunization of children in Canada have been
available without thimerosal.

But the annual flu shot -- which Canadian doctors this year began
pushing on even healthy children over six months of age -- contains the
preservative. And thimerosal is still found in larger, multi-dose
vaccines shipped to Third World countries.

Dr. Laszlo Palkonyay, medical-scientific advisor for Quebec-based flu
vaccine maker Shire Biologics, said a study published in the journal
Pediatrics last September, which was based on a registry of all
psychiatric admissions in Denmark between 1971 and 2000, found no trend
toward an increase in autism rates during the period thimerosal was used
in vaccines in that country. In fact, he said, the incidence of autism
increased after the preservative was removed from vaccines in 1990.

Dr. Deth believes it is more than coincidental that his team's work
"falls directly in line" with some current treatments for autism. For
example, his group found thimerosal inhibits the body's ability to break
down a form of vitamin B12, which doctors are now using, with some
success, to treat autistic children.

Groups such as the B.C.-based Vaccination Risk Awareness Network have
heard from parents convinced routine childhood vaccines sickened or
killed their children, and class-action lawsuits blaming vaccines for
deaths and disorders such as autism have been filed in the United States
and Canada.

Dr. Deth stressed more work needs to be done, and that there are other
risk factors for autism, such as genetic factors and other possible
environmental exposures. For example, antimony, a flame retardant found
in some baby blankets "commonly shows up in kids with autism; they're
not able to excrete it readily."

C National Post 2004