Nav: Home

Study links autism symptoms to change in brain chemistry

December 17, 2015

Researchers reporting in the Cell Press journal Current Biology on December 17 have uncovered a direct link between the behavioral symptoms of people with autism and reduced action of an inhibitory neurotransmitter called GABA. GABA's primary responsibility is to dampen neural activity in the brain.

The findings suggest that drugs that increase brain concentrations of GABA might have potential for autism treatment, the researchers say.

"These findings mark the first empirical link between a specific neurotransmitter measured in the brains of individuals with autism and an autistic behavioral symptom," says Caroline Robertson of Harvard University and MIT's McGovern Institute for Brain Research.

Earlier evidence from genetic studies and animals had suggested an important role of GABA signaling in autism, but direct empirical evidence in humans had been lacking. Studies also showed that people with autism spectrum disorders are slower at a phenomenon called binocular rivalry, which is known to involve inhibition in the brain.

In binocular rivalry, two conflicting images are presented simultaneously, one to each eye. To make out one image or the other, the brain must inhibit neural signals to push one out of visual awareness. Typically, developing individuals suppress a visual image from awareness for many seconds at a time. People with autism, on the other hand, struggle to suppress the visual images.

Robertson, senior author Nancy Kanwisher of MIT, and their colleagues wanted to find out whether this difficulty could be traced to differences in GABA levels in the autistic brain. They asked 21 people with autism and 20 typical control individuals to complete a binocular rivalry task. As expected, adults with autism were slower to suppress the visual images.

The researchers then used magnetic resonance spectroscopy to measure GABA concentrations in the brain while individuals completed the task. Those measurements showed a strong link in typical control participants between binocular rivalry dynamics and levels of GABA. That connection between perception and GABA brain chemistry was completely absent in the brains of people with autism.

"Individuals with autism are known to have detail-oriented visual perception--exhibiting remarkable attention to small details in the sensory environment and difficulty filtering out or suppressing irrelevant sensory information," Robertson says. "It's long been thought this might have something to do with inhibition in the brain, and our findings lend support to this notion."

They note, however, that the GABA dysfunction that they've uncovered may vary substantially among people on the autism spectrum. There are also many other neurotransmitters that may play important roles in the behavioral manifestations of autism.

Further studies by the researchers will examine the genetic basis of the GABA imbalance. They are also examining binocular rivalry dynamics in children with autism and the potential of this phenomenon to serve as an early diagnostic marker.
-end-
This work was funded by a Harvard Milton Fund award, a NARSAD Young Investigator award, an MIT-MGH Strategic Partnership grant, and a grant from the Simons Center for the Social Brain.

Current Biology, Robertson et al.: "Reduced GABAergic Action in the Autistic Brain" http://dx.doi.org/10.1016/j.cub.2015.11.019

Current Biology (@CurrentBiology), published by Cell Press, is a bimonthly journal that features papers across all areas of biology. Current Biology strives to foster communication across fields of biology, both by publishing important findings of general interest and through highly accessible front matter for non-specialists. For more information please visit http://www.cell.com/current-biology. To receive media alerts for Cell Press journals, contact press@cell.com.

Cell Press

Related Autism Articles:

Genes, ozone, and autism
Exposure to ozone in the environment puts individuals with high levels of genetic variation at an even higher risk for developing autism than would be expected just by adding the two risk factors together, a new analysis shows.
A blood test for autism
An algorithm based on levels of metabolites found in a blood sample can accurately predict whether a child is on the autism spectrum of disorder (ASD), based upon a recent study.
New form of autism found
Autism spectrum disorders (ASD) affect around one percent of the world's population and are characterized by a range of difficulties in social interaction and communication.
Autism Speaks MSSNG study expands understanding of autism's complex genetics
A new study from Autism Speaks' MSSNG program expands understanding of autism's complex causes and may hold clues for the future development of targeted treatments.
Paths to Autism: One or Many?
A new report in Biological Psychiatry reports that brain alterations in infants at risk for autism may be widespread and affect multiple systems, in contrast to the widely held assumption of impairment specifically in social brain networks.
Raising a child with autism
Humans are resilient, even facing the toughest of life's challenges.
Explaining autism
Recognizing a need to better understand the biology that produces Autism Spectrum Disorder (ASD) symptoms, scientists at Duke-NUS Medical School (Duke-NUS) and the National Neuroscience Institute (NNI), Singapore, have teamed up and identified a novel mechanism that potentially links abnormal brain development to the cause of ASDs.
Autism breakthrough
Using a visual test that is known to prompt different reactions in autistic and normal brains, Harvard researchers have shown that those differences were associated with a breakdown in the signaling pathway used by GABA, one of the brain's chief inhibitory neurotransmitters.
New options for treating autism
The release of oxytocin leads to an increase in the production of anandamide, which causes mice to display a preference for interacting socially.
The Autism Science Foundation launches the Autism Sisters Project
The Autism Science Foundation, a not-for-profit organization dedicated to supporting and funding autism research, today announced the launch of the Autism Sisters Project, a new initiative that will give unaffected sisters of individuals with autism the opportunity to take an active role in accelerating research into the 'Female Protective Effect.'

Related Autism Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Setbacks
Failure can feel lonely and final. But can we learn from failure, even reframe it, to feel more like a temporary setback? This hour, TED speakers on changing a crushing defeat into a stepping stone. Guests include entrepreneur Leticia Gasca, psychology professor Alison Ledgerwood, astronomer Phil Plait, former professional athlete Charly Haversat, and UPS training manager Jon Bowers.
Now Playing: Science for the People

#524 The Human Network
What does a network of humans look like and how does it work? How does information spread? How do decisions and opinions spread? What gets distorted as it moves through the network and why? This week we dig into the ins and outs of human networks with Matthew Jackson, Professor of Economics at Stanford University and author of the book "The Human Network: How Your Social Position Determines Your Power, Beliefs, and Behaviours".