Autism and its causes: What to know before Trump’s announcement

Health Secretary Robert F. Kennedy Jr. promised earlier this year to determine the cause of autism by September.

A White House announcement about autism is expected Monday afternoon after President Donald Trump’s weekend comment that “I think we found an answer” to the developmental disorder.

Health Secretary Robert F. Kennedy Jr. promised earlier this year to determine the cause of autism by September. That baffled brain experts who say there is no single cause and that the rhetoric appears to ignore decades of science into the genetic and environmental factors that can play a role.

Here’s what we know about autism.

Autism isn’t a disease. It’s a complex developmental condition better known as autism spectrum disorder that affects different people in different ways.

It can include delays in language, learning or social and emotional skills. For some people, profound autism means being nonverbal and having intellectual disabilities, but the vast majority of people with autism experience far milder effects.

There are two main reasons. First, the definition of autism broadened as scientists expanded their understanding of its wide range of traits and symptoms. That led to changes in the criteria doctors use to diagnose autism and improvements in screening.

At the same time, parents increasingly sought a diagnosis as autism became better known and schools began offering educational services they hoped could help their kids.

As late as the 1990s, only children with the most profound symptoms were considered to have autism. In the early 2000s, as the definition began changing, the autism rate was estimated to be 1 in 150 children. The latest count found one in about 31 children are affected by autism spectrum disorder.