Study: Vaccines' mercury causes autism-like signs in mice
By TODD ACKERMAN
June 17, 2004, 1:38AM
Copyright 2004 Houston Chronicle Medical Writer
The mercury preservative used in some childhood vaccines can cause autism-like symptoms in newborn mice, but only in those with a particular genetic susceptibility, according to a new study.
The study, published online by the journal Molecular Psychiatry, comes a month after the Institute of Medicine, an influential adviser of the government, issued a report concluding there is no causal link between vaccines and autism.
"This shows the IOM report was premature," said Dr. Ian Lipkin, a Columbia University researcher and co-author of the study. "Our research shows a biological plausibility to the argument that the interaction of genes and environment could be associated with autism. A large study that doesn't parse out the genetically susceptible would miss the association."
The study was applauded by parents and autism groups that contend vaccines are a cause of the neurological disorder marked by jerky, repetitive movements, a lack of language skills and social withdrawal.
The contention has been fueled by an explosion in autism the last decade that no one can explain. The controversy has concerned public health leaders, who worry that the allegations could undermine a vaccine program considered one of the great medical breakthroughs of the past century. The mercury has been removed from most vaccines in the United States, but it is still commonly used in the Third World.
Dr. Steven Goodman, a member of the panel that prepared the IOM report, said the Columbia study was "tantalizing, but very far from being the kind of link needed to outweigh the human evidence we have."
Goodman stressed that it is unclear whether the mice had autism or were suffering from neurotoxicity, a known effect of mercury. He said "we have a hard enough time defining autism in humans, let alone in mice."
But Goodman acknowledged that if there is a genetic-environmental link to autism involving a small subset of the population, the kind of large human studies that have been done would miss such an association.
The study involved four strains of mice, including one in which mercury had previously been shown to stimulate autoimmune disorders. Newborn mice of each strain were injected with mercury comparable to those used in vaccines.
The three strains of mice with no autoimmune susceptibility showed no effects from the injections, but virtually all the ones with the susceptibility developed problems consistent with children with autism -- delayed growth, abnormal response to new environments, decreased exploration of their environments, brain architecture abnormalities and increased brain size.
Jeff Sell, a Houston attorney with autistic twins, said, "It's reassuring to see some credible, unbiased evidence from a Columbia research team that shows a causal connection between vaccines and what our children have."