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Autism's Rising Prevalence: I See It Every Week

Guest blog post by pediatrician Bob Sears, a primary-care pediatrician in Capistrano Beach, California, and the author of The Autism Book. “Dr. Bob,” as he likes to be known, is one of three pediatrician sons of the well-known pediatrician William Sears and pediatric nurse Martha Sears. More about their “family practice” can be found at

For years, many in the medical community have claimed that autism spectrum disorder (ASD) isn’t truly on the rise – that we simply have better diagnosis. I believe that these numbers reveal autism for what it truly is – a national public health priority.

In the 70s, using different research techniques, ASD was estimated to be about 1 in 10,000. In the 80s, about 1 in 1000.

Now what the CDC does is study groups of 8-year-olds all born in a given year in various cities around the country. It then determines the rate of ASD in those 8 year olds. Here are the data we have so far:

Studied in 2002, the rate of ASD for children born in 1994 was 1 in 150.

In 2006, the rate of ASD for children born in 1998 was 1 in 110.

In 2008, the rate of ASD for children born in 2000 was 1 in 88.

In 2010, the rate of ASD for children born in 2002 was 1 in 68 – this latest report. These are children who were born 12 years ago.

If this rate of increase were to continue, this implies that the ASD rate for children born in 2014, is going to be 1 in what? 40? 30? 20? No one knows.

But I can tell you, as a full-time practicing pediatrician, I’m having the “I’m worried your toddler may have autism” talk with parents almost every week now. It used to be a few times each year, when I started practicing back in 1998. Now, I’m happy when a week goes by without finding a newly suspected case.

I applaud the CDC’s hard work on this matter. One aspect to their research that I see as positive is that they are now going to start tracking groups of four year olds, in addition to eight year olds. This will give us data at younger ages, which will be useful.

However, missing from the CDC report are three keys factors that I would like to see given new emphasis:

1. An acknowledgement that there truly is a real increase and that we are facing a serious problem that continues to grow. Many in the medical community still claim that it’s mostly due to better diagnosis.

2. While much has been discussed about early diagnosis and treatment, we also need to hear a clear commitment – on the part of the CDC and the National Institutes of Health – to find the causes and work on prevention.

3. In particular, I would like to see a greater emphasis on research aimed at uncovering environmental causative factors. Genetics are involved in autism, but I believe that environmental factors are causing the genetic problems in the first place. We need to stop pretending that autism has always been this common. I believe that the dramatic rise in prevalence points to significant environmental causes. We need to find them.

Finally, the CDC report focuses on the fact that a greater proportion of the children being diagnosed with autism have higher IQs than those diagnosed in the past. This is a good trend. But it’s very little consolation to those with autism. It’s still autism. It’s still an enormous financial and educational challenge that affects daily day-to-day life for these families. 

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The Autism Speaks blog features opinions from people throughout the autism community. Each blog represents the point of view of the author and does not necessarily reflect Autism Speaks' beliefs or point of view.