Researchers found that sulforaphane - a chemical found in broccoli and other vegetables - improved behavioral symptoms in some individuals with autism.
The team's findings are published in the Proceedings of the National Academy of Sciences (PNAS).
Autism is a developmental disability characterized by problems with social, emotional and communication skills, as well as repetitive and routine behaviors. Onset usually occurs before the age of 3 years, and the disorder is almost five times more common among boys than girls.
According to the Centers for Disease Control and Prevention (CDC), autism is the fastest growing disability in the US, with prevalence of the disorder increasing 289.5% over the past 12 years. More than 3.5 million Americans are living with autism.
At present, there are no medications that can treat the core symptoms of autism. But in this latest study, researchers found that sulforaphane could reduce certain behavioral symptoms of the disorder by targeting underlying cellular problems.
Sulforaphane boosts body's heat-shock response
Sulforaphane is a chemical found in a number of vegetables, including broccoli, broccoli sprouts, cabbage, cauliflower and Brussels sprouts.
- Around 1 in 68 children in the US have autism
- Approximately 35% of young adults aged 19-23 with autism have never had a job or postgraduate education after leaving high school
- Autism services cost the US $200-400 billion every year.
The chemical is most commonly associated with its cancer-fighting properties. Last year, for example, Medical News Today reported on a study suggesting that broccoli may protect against skin cancer because of its sulforaphane content.
Dr. Paul Talalay, co-author of this latest study and a professor of pharmacology and molecular sciences at Johns Hopkins, and colleagues first discovered the disease-fighting properties of sulforaphane in 1992. They found that it could boost the body's defenses against oxidative stress, inflammation and DNA damage.
But what is more, the researchers later discovered that sulforaphane can enhance the heat-shock response in the body. This is a series of events that protects cells from damage caused by high temperatures, such as when a person has a fever.
Dr. Talalay notes that around half of parents of children with autism say their child's behavioral symptoms significantly improve when they have a fever. This got the team thinking: could sulforaphane be used to induce a heat-shock response in individuals with autism and improve symptoms?
Comparing sulforaphane from broccoli sprouts with a placebo
For their study, the team enrolled 40 adolescents and young men aged 13-27 who had moderate to severe autism.
Of the participants, 26 were randomly assigned to receive either a dose of sulforaphane (9-27 mg dependent on their weight) once a day, which was extracted from broccoli sprouts, while 14 received a daily dose of a placebo.
The researchers note that the participants, their family and the study team did not know what treatments each subject was receiving.
At 4, 10 and 18 weeks after treatment started, a number of autism-related behaviors were measured in the participants using the Aberrant Behavior Checklist, the Social Responsiveness Scale and the Clinical Global Impression scale. Treatment was stopped at 18 weeks.
Behavioral improvements from sulforaphane 'so noticeable'
The researchers found that 4 weeks into the treatment, many of the participants who received sulforaphane started to show improvements in behavioral symptoms, and these improvements continued until treatment ceased.
By 18 weeks, participants who received sulforaphane saw their scores on the Aberrant Behavior Checklist reduce by 34%, while scores on the Social Responsiveness Scale reduced by 17%.
Study co-author Dr. Andrew Zimmerman, a professor of pediatric neurology at the University of Massachusetts, says the team was not shocked by the findings:
"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.
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 [this scale] has been seen for a drug study in autism spectrum disorder."
Furthermore, assessments using the Clinical Global Impression scale revealed that 46% of participants who received sulforaphane showed noticeable improvements in social interaction, 54% showed improvements in aberrant behaviors - such as irritability, awareness, repetitive movements, hyperactivity and motivation - while 42% showed improvements in verbal communication.
The researchers stress, however, that a third of patients had no behavioral improvements with sulforaphane, therefore the compound needs to be tested in a larger sample of individuals with autism - something the team hopes to do soon.
"Ultimately we need to get at the biology underlying the effects we have seen and study it at a cellular level," says Dr. Zimmerman. "I think that will be done, and I hope it will teach us a lot about this still poorly understood disorder."
Sulforaphane may pose other health benefits, too. In 2013, MNT reported on a study claiming the chemical may protect against osteoarthritis, while another study suggested that the broccoli-derived molecule could help prevent or treat breast cancer.