Autism Research Gets Boost With New Cdc Study

The Centers for Disease Control and Prevention (CDC) announced in October that it will allocate $5.9 million for a multi-site study into the causes of autism. One expert said these studies are needed to address widespread assumptions about the disorder's causes.

The study will follow approximately 2,700 children for five years to focus on genetic and environmental factors that contribute to autism. Participating study sites include the CDC headquarters in Atlanta, GA; the Kaiser Foundation Research Institute in California; the Colorado Department of Public Health and Environment; Johns Hopkins University in Maryland; the University of North Carolina at Chapel Hill; and the University of Pennsylvania. Together they make up the Centers for Autism and Developmental Disabilities Research and Epidemiology Network.

The study comes in response to a legislative mandate, the Children's Health Act of 2000 (PL 106-310), that directs the CDC and NIH to increase research into autism. The NIH supports two major research networks to investigate the causes, diagnosis, early detection, prevention, and treatment of autism: the Collaborative Programs of Excellence in Autism and Studies to Advance Autism Research and Treatment Network.

FOCUS ON MATERNAL-FETAL ISSUES

Andrew Zimmerman, MD, who will serve as a consultant for the CDC study at Johns Hopkins, said the research should focus on maternal-fetal issues during pregnancy. He said that while there is abundant evidence that autism occurs before birth and is primarily due to genetic factors, external triggers of the disease seem likely and could include infections, such as rubella; pregnancy labor drugs, such as terbutaline; and environmental factors.

Dr. Zimmerman is Director of Medical Neuroscience at the Center for Autism and Related Disorders at the Kennedy Krieger Institute.

The field is evolving, he said, much as research for childhood cancer and learning disabilities did 10 to 20 years ago. Many assumptions are made about causes of the disorder that lead to fuzzy thinking and expensive treatments without scientific basis.

PETITION TO RESTRICT VACCINES WITH THIMEROSAL DENIED

In other news related to environmental factors in autism, the FDA announced in October that it has denied a petition to restrict the use of vaccines that contain the mercury-based preservative thimerosal. The Coalition for Mercury-free Drugs, a group comprising scientists and parents of children with autism, petitioned the agency in 2004, citing concerns that the preservative is linked to autism.

Only a small number of licensed and approved products still contain thimerosal, and the available evidence supports FDA's conclusion that all currently licensed vaccines and other pharmaceutical drug products containing thimerosal are safe, Jeffrey Shuren, MD, FDA Assistant Commissioner for Policy, wrote in denying the petition.

Beginning in 2001, thimerosal has been removed from vaccines for children. Since the CDC study will focus on children ages 2 to 5, it will limit researchers' ability to examine thimerosal-containing vaccines as a cause of autism. But Dr. Zimmerman said this issue has already been studied well. He cited a 2004 report by the Institute of Medicine, Immunization Safety Review: Vaccines & Autism, that concluded that there is no association between vaccines and autism. There may be some children with immunologic vulnerability that might contribute to individual exceptions where a vaccine reaction occurs, he said. Right now, we see the need for prospective studies.