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Children with Autism May Have Inherited Abnormal "Micro-Movement" Patterns

ByAllison EckNOVA NextNOVA Next

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Autism may be a neurodevelopmental disorder, but some scientists are turning to physics to understand the subtleties of its symptoms.

According to unpublished results presented Sunday at the 2014 Society for Neuroscience (SfN) annual meeting in Washington, D.C., children with autism and their parents frequently share anomalous movement patterns that are invisible to the naked eye. While it’s widely known that autistic people have problems with motor skills, the “micro-movements” referred to in this new study are smaller, less perceptible, and not within a person’s conscious control.

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Subtle body movements could reveal whether or not a person has autism—and these micro-patterns might even be genetic.

Researchers recorded the movements of 30 people with autism, eight neurotypical adults, and 21 parents of children with autism as they pointed at and reached for a target in the middle of a screen about 100 times in a row. What they found is that all subjects demonstrated brief increases in speed along the way, called peripheral spikes (or “p-spikes”). But these minuscule gestures actually broke down into different types.

Here’s Sarah DeWeerdt, writing for the Simons Foundation Autism Research Initiative:

In healthy adults, most p-spikes occur at either end of the loop: when beginning to reach the arm outward or at the end of pulling it back. In people with autism, the pattern of spikes “is totally randomly distributed all over the place,” says Di Wu, a graduate student in Jose’s lab who presented the poster.

Typically developing children 3 to 5 years of age also have random patterns of p-spikes, similar to the autism group, the researchers found. This suggests that p-spikes normally become more organized with age, but that this maturation doesn’t occur in people with autism. The autism group in the study included individuals between 10 and 30 years old.

The researchers also measured p-spikes in 14 mothers and 7 fathers who have a child with autism. Surprisingly, most of these unaffected parents have movement patterns like those of their children, and not like those of typical adults. This suggests that genetics plays a strong role in p-spike patterns, the researchers say.

While the finding doesn’t suffice as an autism marker on its own (not all people with irregular p-spikes have autism), it could at least supplement existing diagnostic tests. More erratic p-spikes are associated with lower functioning overall, too. What’s still uncertain is whether or not p-spikes can help with early diagnosis, since neurotypical three- to five-year-olds also evidence the aberration. But if there’s reason to believe a young child might have autism, then testing their parents’ movements could help evaluate the likelihood that they has the disorder.

Previous research has suggested that autistic people are prone to sensory overload —so in addition to irregular self-movement, visual perception of movement could be suppressed, too. Another unpublished study presented at the SfN meeting has shown that mice with Angelman syndrome—an autism-related disorder caused by mutations or deletions of the maternal copy of the UBE3A gene—exhibit abnormal brain responses to motion.

Here’s Virginia Hughes, also writing for the Simons Foundation Autism Research Initiative:

The researchers measured changes in brain activity while the animals watched vertical black bars moving from left to right at various speeds. When watching a visual stimulus change from a slow to a high speed, normal mice show a burst of activity in ‘higher-order’ visual areas, meaning those that process the visual information after it passes through other areas of cortex. By contrast, the Angelman mice show no such activation.

This difference occurs only after a certain age, however. Mice open their eyes at 14 days old. At 20 days of age, the researchers saw no differences in brain activity between Angelman mice and controls. By 85 days, the differences were stark. This age dependence is exciting, Townsend says. “It suggests that there might be a therapeutic intervention window.”

Clinical trials, for example, may rely on either of these tests (micro-movement analysis or visual cortex imaging, if it’s proven in humans) to assess a drug’s effectiveness, adding to the increasing number of methods that are being considered for early intervention.