David C. Rettew, MD, is a child psychiatrist at the UVM Medical Center and director of the Child & Adolescent Psychiatry Residency Program.

David Rettew, MD, is the Director of the Pediatric Psychiatry Clinic at the University of Vermont Medical Center and Associate Professor of Psychiatry and Pediatrics at the Larner College of Medicine at UVM.

Data released just this month from the Center for Disease Control show that an autistic spectrum disorder affects 1 in 68 children and 1 in 42 boys. These numbers haven’t increased from the last report about two years ago but represent a startling increase in prevalence compared to just a few decades earlier. This rise has raised alarm for parents and the medical community alike.  What could be behind this?

Let’s first start with what is not behind it: vaccines. While there remains some vocal critics, study upon study continue to show no link between vaccines and autism. 

Furthermore, what may look like an actual increase in prevalence is at least in part driven by three well documented phenomena. 

  • The first is that the medical community is being much more vigilant about screening and investigating autism which in turn leads to many more children being diagnosed. 
  • Second, the threshold for what “counts” as autism has been decreasing.  Thirty years ago, it was only the very classically presenting and most severely affected individuals who received a diagnosis.  By contrast, current standards allow the diagnosis to be given to children who can be quite verbal and can be functioning relatively well but still struggling in particular ways. 
  • Third, in instances when more than one diagnosis could be applied, autism is becoming the preferred “choice.”   A large study looking at special education records of over 6 million children, for example, found that, from 2000 to 2010, the increase in children receiving services for autism moved in synch with the decrease in children receiving services under other categories such as intellectual disability, specific learning problems, or other diagnoses that some, but certainly not all, children with autism could alternately receive. 

The question remains, however, whether or not there also could be other things that might be causing an albeit smaller “real” increase in autism. One factor that probably is accounting for some of the rise in autism prevalence is increasing average parental age at the time a child is born, but this effect is probably small.  There is much speculation about other possible factors from internet dating sites to environmental toxins, but solid scientific evidence here is more difficult to obtain. 

The current data just released suggest that perhaps we have hit a plateau with regard to the rate of autism diagnoses. While there will likely be further adjustments in the future, it remains important that parents of infants and toddlers collaborate with their primary care providers to ensure that the recommended screenings are being done and any concerns about autism are brought up and discussed.

David Rettew, MD, is the Director of the Pediatric Psychiatry Clinic at the University of Vermont Medical Center and Associate Professor of Psychiatry and Pediatrics at the Larner College of Medicine at UVM. He is the Program Director for the Child & Adolescent Psychiatry Fellowship Program. He is the author of Child Temperament:  New Thinking About the Boundaries Between Traits and Illness.  You can follow him on Twitter at @PediPsych. 

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