July 05, 2006 -- Pervasive developmental disorders (PDD) like autism and Asperger Syndrome have been on the rise for years. Measles Mumps Rubella (MMR) vaccines and thimerosal-containing vaccines (which are approximately 50 percent ethylmercury) have been suggested as possible causes. A new MUHC study, published in the scientific journal Pediatrics today, assesses the link between childhood immunizations and PDD in 28,000 Quebec children and finally clears MMR vaccines and thimerosal-containing immunizations as risk factors.

"There is no relationship between the level of exposure to MMR vaccines and thimerosal-containing vaccines and rates of autism," says Dr. Eric Fombonne, Director of Pediatric Psychiatry at the Montreal Children's Hospital of the MUHC and lead investigator of the new study. Thimerosal was used to prevent bacterial and fungal contamination in the manufacture of various vaccines until its elimination from vaccine formulas in 1996 in Quebec. "According to our data, the incidence of autism was higher in children who were vaccinated after thimerosal was eliminated from vaccines," says Dr. Fombonne.

"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 resurgence of the measles, which caused the deaths of several young children in Europe." Dr. Fombonne's study indicates that autism rates continued to increase even with reductions in the use of MMR vaccinations. "We hope this study will finally put to rest the pervasive belief linking vaccines with developmental diseases like autism," says Dr. Fombonne.

Autism is a neuropsychiatry disorder that impairs a child's ability to communicate and interact with others. The prevalence is about 65 cases per 10,000 people (about 1 child in 155), making autism one of the most common childhood disorders. The Psychiatry Department at the Montreal Children's Hospital sees about 350 new cases of autism each year. However, Dr. Fombonne stresses that there is no demonstrated autism epidemic. He attributes the rise in autism rates to a broader definition of autism and greater awareness of the disorder.

The Montreal Children's Hospital is the pediatric teaching hospital of the McGill University Health Centre (MUHC). The institution is a leader in the care and treatment of sick infants, children and adolescents from across Quebec. The Montreal Children's Hospital provides a high level and broad scope of health care services, and provides ultra-specialized care in many fields including: cardiology and cardiac surgery; neurology and neurosurgery, traumatology; genetic research; psychiatry and child development and musculoskeletal conditions, including orthopedics and rheumatology. Fully bilingual and multicultural, the institution respectfully serves an increasingly diverse community in more than 50 languages. www.thechildren.com

The McGill University Health Centre (MUHC) is a comprehensive academic health institution with an international reputation for excellence in clinical programs, research and teaching. The MUHC is a merger of five teaching hospitals affiliated with the Faculty of Medicine at McGill University — the Montreal Children's, Montreal General, Royal Victoria, and Montreal Neurological Hospitals, as well as the Montreal Chest Institute. Building on the tradition of medical leadership of the founding hospitals, the goal of the MUHC is to provide patient care based on the most advanced knowledge in the health care field, and to contribute to the development of new knowledge.

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