Since the introduction of the Measles, Mumps and Rubella (MMR) vaccine, a number of scientists and parents have argued that the vaccine is responsible for an increase in pervasive developmental disorders (PDD), such as autism and Asperger syndrome. And while it's true that there has been a rise in PDDs over the years, new research shows that there is no link between them and the MMR vaccine.
The controversy associated with the MMR vaccine stems from a theory that thimerosal (ethylmercury), used to prevent bacterial and fungal contamination during the manufacture of the vaccine, is the culprit behind the rise in PDDs. But a new McGill University Health Center (MUHC) study, published in the journal Pediatrics, counters this claim with findings from a study involving 28,000 Quebec children. "There is no relationship between the level of exposure to MMR vaccines and thimerosal-containing vaccines and rates of autism," says Dr. Eric Fombonne, lead investigator of the new study.
The study discounts thimerosal as the culprit because Quebec ceased using it as a way to prevent bacterial and fungal contamination in 1996. "According to our data, the incidence of autism was higher in children who were vaccinated after thimerosal was eliminated from vaccines," says Dr. Fombonne.
Unfortunately, the fear caused by those who believed thimerosal vaccines were related to PDDs - the most infamous case being Dr. Andrew Wakefield's report that appeared in the medical journal The Lancet, which was later retracted by its co-authors - had dire consequences. "In the past, concern about a potential link between MMR vaccinations and autism led some parents to take the drastic step of refusing to inoculate their children against dangerous childhood diseases like measles," says Dr. Fombonne. "This action resulted in [a] resurgence of the measles, which caused the deaths of several young children in Europe."
"We hope this study will finally put to rest the pervasive belief linking vaccines with developmental diseases like autism," says Dr. Fombonne. Each year, the Psychiatry department at the Montreal Children's Hospital assesses approximately 350 new cases of autism. Rather than associating this rise with any particular drug or environmental factor, Dr. Fombonne suggests that the increase could be explained by broader definitions and awareness of the disorder.
Source: McGill University