U.S. autism rates reach new height: CDC
NEW YORK |
(Reuters) - About one in 88 children in the United States has autism or a related disorder, the highest estimate to date and one that is sure to revive a national argument over how the condition is diagnosed and treated.
The estimate released on Thursday by the Centers for Disease Control and Prevention represents an overall increase of about 25 percent since the last analysis in 2006 and a near-doubling of the rate reported in 2002.
Among boys, the rate of autism spectrum disorders is one in 54, almost five times that of girls, in whom the rate is one in 252.
"One thing the data tells us with certainty - there are many children and families who need help," said CDC Director Thomas Frieden. "We must continue to track autism spectrum disorders because this is the information communities need to guide improvements in services to help children."
Advocates for people with autism seized on the apparent spike in the prevalence of the disease to call for more research to identify its causes and services for those affected by it.
"This is a national emergency and it's time for a national strategy," said Mark Roithmayr, president of the research and advocacy group Autism Speaks. He called for a "national training service corps" of therapists, caregivers, teachers and others who are trained to help children with autism.
Some researchers have questioned whether the increases over the last decade are real or reflect greater awareness that has led parents and teachers to see symptoms of autism in children who would not have received the diagnosis a generation ago.
"Inevitably when these statistics come out, the question is, what is driving the increase?" said Roithmayr. Better diagnoses, broader diagnostic criteria and higher awareness, he estimated, account for about half the reported increase.
The new analysis from the CDC comes from the Autism and Developmental Disabilities Monitoring Network, which currently operates in 14 states.
To determine whether a child has autism or a related disorder, what CDC calls "clinician reviewers" examined the medical and school records of 8-year-olds in those states and also conducted screening. Children whose records included either an explicit notation of autism-spectrum disorder or merely descriptions of behavior consistent with the disorder were counted as falling on the autism spectrum.
CDC investigators warned, however, that the 14 sites are not "nationally representative." As a result, the rate of autism being reported on Thursday in CDC's Morbidity and Mortality Weekly Report, "should not be generalized to the United States as a whole," they wrote.
Autism spectrum disorders are marked by a suite of symptoms, all arising from atypical brain development that results in problems with socialization, communication, and behavior.
Although the disorder can be mild or severe, in general children with autism have difficulty communicating and making friends. Many find it painful to look other people in the eyes, which impairs their ability to understand what others are thinking and feeling.
There is no brain-imaging test for autism, let alone a blood test or other rigorously objective diagnostic. Instead, physicians determine whether someone fits the criteria laid out in the American Psychiatric Association's Diagnostic and Statistical Manual, or DSM.
The manual has undergone significant changes over the years, including in the diagnostic criteria for autism. In its current version, someone must fit at least eight of 16 criteria, including symptoms involving social interaction, communication, and repetitive or restricted behaviors and interests.
The previous version was stricter, describing one diagnostic criterion as "a pervasive lack of responsiveness to other people." In the current manual, that became "a lack of spontaneous seeking to share . . . achievements with other people" and friendships that appear less sophisticated than the norm for a child's age.
The earlier manual also required "gross deficits in language development" and "peculiar speech patterns" for a diagnosis, while the current one lists difficulty "sustain(ing) a conversation" or "lack of varied . . . social imitative play."
Psychologist Morton Ann Gernsbacher, a professor of psychology and autism researcher at the University of Wisconsin, Madison, and others have cited these changes to question the reality of the reported autism increase.
Scientists had long estimated that 90 percent of autism risk was genes and 10 percent reflected environmental factors. But a 2011 study of twins by scientists at Stanford University concluded that genes account for 38 percent of autism risk and environmental factors 62 percent.
Exactly what those factors are, however, remains the subject of intense research, with two large studies funded by the National Institutes of Health examining everything from what the mother of a child with autism ate during her pregnancy to what cleaners were in the house and what pollutants were in the dust.
"There is not a clear frontrunner" among possible environmental causes of autism, said Craig Newshaffer, chair of the Department of Epidemiology and Biostatistics at Drexel University School of Public Health and lead investigator of one of the NIH-sponsored studies.
There is, however, what he called "good evidence" that any environmental culprit is present during the second or third trimester, the peak of synapse formation. Scientists believe that faulty brain wiring underlies autism.
They have also focused on factors that have changed in the last two decades, including pregnant women's use of certain antidepressants, increasing parental age and the rise in pre-term births and low-birth weight babies, said Newshaffer.
Research funded by Autism Speaks found that autism costs the United States $126 billion annually. That reflects the cost of healthcare, special education and other services, as well as loss of productivity, underemployment and unemployment among adults with autism.