It's abundant in cruciferous vegetables like broccoli, cauliflower, and cabbage and has been linked to a number of health benefits in the past. Now researchers, building on the way the chemical, sulforaphane, affects cells' stress response, have found that it may also reduce certain symptoms of autism — at least in very high doses.

Many parents of autistic children have noticed that their children's social interactions and language skills seemed to improve when their children had a fever. Researchers have studied this phenomenon and believe that it’s because fever activates the heat-shock response, which reduces inflammation in cells.

The improvements seen on the Social Responsiveness Scale were particularly remarkable.

Separately, another group of researchers had isolated sulforaphane, noticing that it plays an important role in the cellular stress response, the key to its benefits for breast health, heart health, and even a longer life.

So the two research teams got together to investigate whether sulforaphane might affect autism symptoms.

They had 44 young men (ages 13-27) with autism take either sulforaphane supplements or placebo for 18 weeks. All the participants had moderate or severe autism. Measures of behavior and social interaction were rated by caregivers and by the research staff at 4, 10, and 18 weeks after treatment began, and then at week 22, four weeks after the treatments were discontinued.

The study was double-blind — the researchers and participants (and caregivers) were unaware of which participants were getting the active treatment and where were receiving placebo.

“When we broke the code that revealed who was receiving sulforaphane and who got the placebo, the results weren't surprising to us, since the improvements were so noticeable,” said Zimmerman.

“The improvements seen on the Social Responsiveness Scale were particularly remarkable, and I've been told this is the first time that any statistically significant improvement on the SRS has been seen for a drug study in autism spectrum disorder.”

The participants’ average scores on the Aberrant Behavior Checklist decreased by 34%, and on the Social Responsiveness Scale about 17%. On the Clinical Global Impression scale, about half of the participants in the sulforaphane group showed improvements in social interaction, aberrant behaviors, and verbal communication. But about a third of the participants didn’t seem to show changes in any of the measures.

The positive changes that were seen in many of the participants dissipated by the 22-week mark, suggesting that it was indeed the sulforaphane that had the effect. It’s important to point out that the doses of sulforaphane used were very high, and many times what one could take in through food.

Of course, more research will be needed to understand how the compound works, and what dosing might be most effective. The team is currently working on another study to look at the effects of the compound in a larger number of people.

“Ultimately we need to get at the biology underlying the effects we have seen and study it at a cellular level. I think that will be done, and I hope it will teach us a lot about this still poorly understood disorder,” Zimmerman said.

The research was carried out by teams at Johns Hopkins University and MassGeneral Hospital, and is published in Proceedings of the National Academy of Sciences.