Autism Spectrum Disorder – Incidence Rates

There’s been a lot in the news lately about the CDC reporting an increase in the incidence rates of Autism Spectrum Disorders. The recent studies (from the CDC) focus on incidence rates from 2000 to the present. The Wikipedia article on Autism shows a chart with an almost linear growth shown from 1996 to 2007.

Autism Rates by Eubulides used under a Creative Commons Attribution Share Alike license

However, based on data reported  by the National Institute of Health and the Center for Disease Control, the reported incidence rates of Autism Spectrum Disorder since the 1970′s look like this:

Autism Incidence Rate Chart

I didn’t include all years in this chart because the data-points are taken specifically from the CDC and NIH reports as well as a few other reports from years prior to 2000.

The big question is WHY? Broader definitions? Better diagnostic procedures? The scary part is that if you do the math, there has been an increase of 3900% in the incidence of Autism Spectrum Disorders from 1970 to 2013 from .5 per 1000 to 20 per 1000 in a 43 year period. Even if we say that definitions are broader and diagnosis is better, that’s still a horrifying increase in the incidence rates of this spectrum of disorders. I just saw that Time published a study on June 1, 2013 about genetic markers for Autism. More reading to do….

Why do you think Autism Spectrum Disorders have increased so dramatically in the last 50 years?