Autism has been in the news a lot this past week. The big story is a new study from the Centers for Disease Control and Prevention (CDC) about the prevalence of autism in the United States. Using data collected from both educational and health care sources, the CDC now reports that autism spectrum disorders (ASD), comprising autism, unspecified pervasive developmental delay (PDD-NOS) and Asperger disorder, have risen from one case for every 88 children in 2008 to one in 68 as of 2010. This represents an increase of about 30%.

I spoke with a colleague who specializes in developmental pediatrics, who expressed a lack of surprise at these numbers. They continue a trend that has already been demonstrated in numerous prior epidemiological studies, though the exact cause continues to elude us. This study doesn’t say anything about what’s actually causing these increases.

What this new report tells us is “how much” and “who.” Breaking down the numbers, we see that white children are more likely to carry an ASD diagnosis than black or Hispanic children, and that there is a great deal of variation throughout the country. (The study used data collected from 11 states to extrapolate rates for the US as a whole.) Boys are much more likely to be affected than girls, and nearly half of diagnosed patients had at least average intelligence.

As a pediatrician, the number that jumped out most to me is that only 44% of children with ASD diagnoses had a documented developmental evaluation by the time they reached 36 months of age. Though some ASD patients can present with very subtle findings early on, it worries me that 89% of them had documented concerns about their development by the same age. It seems that a large proportion of these patients are going too long without being evaluated even after problems are noted. Screening for delays in speech, motor, and social development during infant and toddler well-child checks is one of the most important things medical providers do, with the goal to get children into necessary therapies as promptly as possible. For many of these patients, it appears they didn’t get the attention and help they needed as early as they ought have.

Of course, what we would most like to know is what’s responsible for the rise in autism. It’s very frustrating to see these data and have little explanation for them. For all the pseudoscience and controversy, one of the few things we can know with certainty is that vaccines aren’t responsible. (In an amusing addendum to the week’s news, Donald Trump made the exciting career leap from laughingstock phantom gubernatorial candidate to laughingstock public health expert. With a series of tweets linking vaccines to the rise in autism, Trump proved to the world he understands medical science just as well as he grasps his own political appeal.)

Whatever the cause of autism, emerging evidence points to it happening early in development. In the other big news of the week, a new study in the New England Journal of Medicine reports evidence of brain abnormalities in autistic patients that likely began before birth. Comparing postmortem tissue samples from children with ASD against tissues from unaffected children, researchers found disorganization in nerve cells in the former group, a change that likely started prenatally.

At least some of this is probably related to genetics. Beyond that, however, the “why” of autism remains unclear. What is encouraging, according to one of the study’s authors, is that the disorganization was only found in certain areas of the brain, indicating that therapy may help mitigate the effects of ASD.

Viewed together, these two reports serve to remind pediatricians and other providers of how very important developmental screening is. Along with checking for normal growth and ensuring that our patients are as protected as possible against preventable diseases, we must be vigilant in detecting the delays that may be the earliest signs of ASD. Parents and teachers should also be sure to communicate with medical providers when they have concerns. Together, we can make sure these children get the help they need as early as possible.