Earlier this week, the LA Times ran a provocative article under the questioning headline above. It suggested that autism’s twentyfold increase over the last generation may be “more of a surge in diagnosis than in disease.” In fact, scientific evidence suggests that autism’s dramatic increase is only partially explained by improved screening and diagnosis.
Some of the clearest evidence of this increase comes from research documenting a 600 percent jump in autism caseload in California between 1992 and 2006. In related studies (here and here), Peter Bearman estimated that around 42 percent of the increase can be explained by changes in diagnostic methods and awareness with another 11 percent possibly due to increases in parental age at the time of conception (a known risk factor).
Taking into account all the factors that have been studied, this leaves approximately half of the increase due to still-unidentified factors. Through research, we’re increasing our understanding of these influences. For example, we now know that prematurity and extreme low-birth weight increase autism risk in babies. Certainly survival rates for premature and very low birth weight infants have increased considerably over the last twenty years.
While no single factor is likely to explain the marked increase in autism’s prevalence, researchers agree that a number of influences likely work together to determine the risk that a child will develop an autism spectrum disorder (ASD).
Bottom line: It is undeniable that more children are being diagnosed with ASD than ever before. The need for increased funding for autism science and services has never been greater. Autism costs society is a staggering $35 billion per year. And with more cases, that figure is likely to increase. Fortunately, there is clear evidence that earlier identification and intervention and supports throughout the lifespan can improve outcomes and quality of life.
If you are concerned about your child’s development, please see the “Learn the Signs” page of our website. If you are an adult struggling with issues that might be related to autism, please follow the hyperlinks to our resource page for adults and our page on Asperger Syndrome.
Got more questions? Send them to GotQuestions@autismspeaks.org. And join our next live webchat with Dr. Dawson and her co-host, Autism Speaks assistant vice president and head of medical research Joe Horrigan, MD on January 5th. More information on their monthly webchats here.