There is no one factor that causes autism — or explains its growing prevalence. Researchers are seeking explanations for the surge. Here are some possibilities.
When President-elect Donald J. Trump mused in a recent television interview about whether vaccines cause autism — a theory that has been discredited by dozens of scientific studies — autism researchers across the country collectively sighed in frustration.
But during the interview, on NBC’s “Meet The Press,” Mr. Trump made one passing comment with which they could agree: “I mean, something is going on,” he said, referring to skyrocketing rates of autism. “I think somebody has to find out.”
What is going on? Autism diagnoses are undeniably on the rise in the United States — about 1 in 36 children have one, according to data the Centers for Disease Control and Prevention collected from 11 states, compared with 1 in 150 children in 2000 — and researchers have not yet arrived at a clear explanation. They attribute most of the surge to increased awareness of the disorder and changes in how it is classified by medical professionals. But scientists say there are other factors, genetic and environmental, that could be playing a role too.
Autism spectrum disorder, as it is officially called, is inherently wide-ranging, marked by a blend of social and communication issues, repetitive behaviors and thinking patterns that vary in severity. A mildly autistic child could simply struggle with social cues, while a child with a severe case could be nonverbal. There is no blood test or brain scan to determine who has autism, just a clinician’s observations.
Because there is no singular cause of autism, scientists say there is therefore no singular driver behind the rise in cases.
But at the heart of the question is an important distinction: Are more people exhibiting the traits of autism, or are more people with such traits now being identified? It seems to be both, but researchers really aren’t sure of the math.