Long-Term Study May Help Explain What Causes Autism

For more than 20 years, researchers have conducted a long-term study on autism – involving more than 115,000 children— looking into what causes it, and how it might be prevented.

"There are certainly strong genetic factors that are at play, but it's probably not a single factor," said Dr. Mady Hornig, Columbia University.

Doctor Mady Hornig is one of the study's researchers with Columbia's Mailman School of Public Health.

For her, the research is personal. Her son is on the autism spectrum.

The study involved blood and genetic testing, and detailed health questionnaires.

What did they find?

"What I call the 'three strikes hypothesis' - the genes, the environment, and the timing – together," said Dr. Hornig.

The hypothesis is that multiple circumstances need to come together, to create the conditions for autism.

That includes certain genetic markers.

And what they call 'environmental conditions' – specifically, inflammation in the body accompanied by a high fever during a very specific time in the pregnancy -- the second trimester, when critical neural pathways are developing.

Researchers looked closely at how those fevers in mothers were treated.

"When the mothers report that they have an infection, whether they have a fever, whether they took something for the fever, or didn't, and what they took for the fever, how long they took it," said Dr. Hornig.

Researchers stress it is important for pregnant women to discuss with their doctors... If they ever get a fever.

"Not allowing a fever to continue in a prolonged fashion is an important aspect," said Dr. Hornig.

In the study, a small subset of mothers took ibuprofen to reduce their fever, and researchers found.

"Zero. There were zero cases of autism among mothers who had fever during pregnancy, who took ibuprofen," said Dr. Hornig.

The autism study is ongoing with researchers continuing to mine the data.

"It's a very, very rich resource," said Dr. Hornig. 

In the hopes it can eventually provide answers to all parents of children with autism.

Scripps National: By Maya Rodriguez, Scripps National Desk.