KIDS
October 5, 2012

Autism's Underlying Neural Processing Issues

Researchers may have found a treatment for one form of the disorder. GABA levels matter, too.

Autism spectrum disorder (ASD) is one of the most complex neurological disorders there is, with a wide range of behavioral and cognitive symptoms. The causes of autism, of course, are even more elusive. Researchers are beginning to get a clearer picture of what’s going on in the brains of people with autism. But we still have a ways to go.

One new study offers promise for a potential treatment for fragile X syndrome, a type of ASD that’s caused by a single-gene mutation. Intellectual impairment and social withdrawal are the core deficits in fragile X, and, according to the CDC, about 1 in 4,000 males and 1 in 6,000 to 8,000 females are born with the disorder.

The researchers found that certain behaviors were improved, particularly on the social-avoidance measure.

Earlier research had found that the syndrome may result from reduced levels of the neurotransmitter gamma-amino butyric acid (GABA). Researchers believe that the social deficits may be a direct result of impaired GABA function.

Researchers had tested a compound called Arbaclofen or STX 209, which enhances GABA levels, in mice, and found that it reduced symptoms in the mouse equivalent of fragile X. But it had not been tested in humans until now. In the current study, people with fragile X, ranging from six to 39 years old, were given the drug over a six-week-long treatment period; adults took 10 mg doses three times daily, while younger participants took it twice daily.

The participants were rated on the Aberrant Behavior Checklist, which tests for stereotypic or repetitive behavior, irritability, hyperactivity, and lethargy or withdrawal. The researchers found that certain behaviors were improved, particularly on the social-avoidance measure. Irritability was the only behavior that was no different from participants who had taken Placebo.

The researchers are hopeful that the treatment could be applied to a larger population with other types of ASD. "Additional studies also are suggesting that STX 209 can be helpful for autism without fragile X syndrome,” said author Randi Hagerman of the UC Davis MIND Institute in a news release. “Until now, there have been no targeted treatments available for autism. This appears to be the first."

The results of a second study suggest that the social, behavior and language issues seen in people with ASD may be the result of an overall deficit in neural processing, rather than a constellation of problems in different areas of the brain.

Another study just released is aimed at understanding the global changes that are present in the autistic brain. "Within the autism research community, most researchers are looking for either a dysfunctional brain region or inadequate connections between brain regions," said lead study author Ilan Dinstein of Carnegie Mellon University. "We're taking a different approach and thinking about how a general characteristic of the brain could be different in autism—and how that might lead to behavioral changes."

Dinstein and his team used magnetic resonance imaging (MRI) to see what was going on in the brains of people with autism during three different sensory conditions: Watching dots move across a screen, listening to a tone, and feeling puffs of air on their hands. The researchers found that their brains showed “noisy responses” to all the conditions, meaning that neural transmission was less uniform than in controls.

These results suggest that the social, behavior and language issues seen in people with ASD may be the result of an overall deficit in neural processing, rather than a constellation of problems in different areas of the brain. The researchers hope that the results will lead to a greater understanding not just of autism, but of other neurological disorders and diseases like schizophrenia and epilepsy.

The first study was published in Science Translational Medicine, the second in Neuron.

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