By Pamela Weintraub on January 18, 2009 in Emerging Diseases
This now in from the U.C. Davis M.I.N.D. Institute:
A study by researchers at the UC Davis M.I.N.D. Institute has found that the seven- to eight-fold increase in the number children born in California with autism since 1990 cannot be explained by either changes in how the condition is diagnosed or counted - and the trend shows no sign of abating.
Published in the January 2009 issue of the journal Epidemiology, results from the study also suggest that research should shift from genetics to the host of chemicals and infectious microbes in the environment that are likely at the root of changes in the neurodevelopment of California's children.
"It's time to start looking for the environmental culprits responsible for the remarkable increase in the rate of autism in California," said UC Davis M.I.N.D. Institute researcher Irva Hertz-Picciotto, a professor of environmental and occupational health and epidemiology and an internationally respected autism researcher.
Hertz-Picciotto said that many researchers, state officials and advocacy organizations have viewed the rise in autism's incidence in California with skepticism.
The incidence of autism by age six in California has increased from fewer than nine in 10,000 for children born in 1990 to more than 44 in 10,000 for children born in 2000. Some have argued that this change could have been due to migration into California of families with autistic children, inclusion of children with milder forms of autism in the counting and earlier ages of diagnosis as consequences of improved surveillance or greater awareness.
Hertz-Picciotto and her co-author, Lora Delwiche of the UC Davis Department of Public Health Sciences, initiated the study to address these beliefs, analyzing data collected by the state of California Department of Developmental Services (DDS) from 1990 to 2006, as well as the United States Census Bureau and state of California Department of Public Health Office of Vital Records, which compiles and maintains birth statistics.
Hertz-Picciotto said that the study is a clarion call to researchers and policy makers who have focused attention and money on understanding the genetic components of autism. She said that the rise in cases of autism in California cannot be attributed to the state's increasingly diverse population because the disorder affects ethnic groups at fairly similar rates.
"We're looking at the possible effects of metals, pesticides and infectious agents on neurodevelopment," Hertz-Picciotto said.
The study gives credence to the suggestion, voiced more loudly in recent years, that the burgeoning epidemic of Lyme disease and other tick-borne infections may be driving part of the autism increase.