Researchers have identified a mechanism in the brains of some people with autism spectrum disorder that may explain "noisy brain,” in which those with ASD are unable to sift out important information in social settings or visual information becomes overwhelming.
The study, published in the journal Science Translational, looked at the GABA receptors in the brain, which control nerve cells. Some believe there is an imbalance in the brain’s ability to regulate signals in those with ASD, and that perhaps a medication could help even those signals out.
Prof. Grainne McAlonan, a neuroscientist at King's College London, U.K., and her team measured levels of GABA in the brains of 44 adults -- 19 with autism and 25 without it.
Researchers gave some test subjects a 30 mg single dose of the experimental drug arbaclofen -- a drug that modifies levels of GABA in the brain. Others received a placebo.
The test subjects were then shown a computer-generated image involving vertical lines, four large dots and a small one that would flicker almost imperceptibly, while scientists measured brain levels of GABA with EEG and Magnetic Resonance Spectroscopy.
Those with autism who received arbaclofen showed brain activity that closely matched people without a diagnosis of the disorder.
The study clearly points to a reason why some people with autism may experience distressing symptoms, and
that perhaps medications that balance GABA in the brain might help. There are no approved treatments for symptoms of autism.
"If we understand the mechanisms better then at least we can offer people choices. And at the moment, there are very few choices,” says McAlonan.
It is a small but important study, says Dr. Evdokia Anagnostou, assistant director at the Bloorview Research Institute at Toronto’s Holland Bloorview Kids Rehabilitation Hospital.
"What they're showing with this particular experimental task is that they can connect with a single dose of medication in this small sample. They can correct some of the noisiness in the brain by giving a dose of arbaclofen," says Anagnostou, who is also the Research Chair in Translational Therapeutics in Autism Spectrum Disorder at Holland Bloorview.
Her team is part of a trial of daily doses of arbaclofen in 90 children with ASD in Canada.
Recruitment has been completed with data expected in June. Similar studies are underway in Europe.
But despite the encouraging signs for the drug, Anagnostou says it remains experimental and not available to the general public in Canada.
"I know it's very frustrating for families. … It's important that we wait for the trials,” she says.
Studies of arbaclofen were first conducted nearly a decade ago. But they were abandoned by the company that owned the patent because the results showed little to no benefit -- even though some parents of children with autism insisted the medication had made a difference in their children's behaviour.
McAlonan says it could be because initial studies took all comers with autism, but this medication may work specifically on those with autism who show the biological mechanism involving GABA.
“So that has meant that possibly we've been missing out on identifying strategies that might actually help some people,” McAlonan says. “Because there's no way that one kind of intervention -- pharmacological intervention or psychological intervention -- will help all people with autism. Everybody has different needs. And not all people with autism even needed a treatment per se.”
The Simons Foundation purchased the patent to arbaclofen, and is sponsoring research into its use.
