When people move, they typically have a certain level of unintentional, imperceptible motion. For most people, these motions largely disappear as they age. A new study from Indiana University and Rutgers University finds that people with autism spectrum disorder (ASD) have more of these movement fluctuations than typically developing individuals. The movement patterns could offer a method for identifying the severity of an individual’s autism.
In this blinded study, the researchers analyzed data from a movement task. The researchers outfitted the participants—30 people aged 3 to 30 with ASD, eight neurotypical adults, and 21 parents of children with ASD—with a high-sensitivity movement sensor attached to their arm. The sensor recorded 240 movements per second as the participants touched a moving spot on a screen. The spot moved continuously and the participants had to extend their arm to touch the spot about 100 times.
The researchers developed a quantitative method for analyzing the participants’ movements. Their analytical method focused on local spikes in speed, or the normally imperceptible movements that occur while an individual makes an intentional motion. These small movements are typically filtered out as “noise,” but they were the focus of this study.
The small fluctuations in movement—called peripheral spikes, or p-spikes—typically occur at the beginning or end of the arm extension movement for neurotypical adults. As the neurotypical adults extended and retracted their arms, there were not many p-spikes. The people with ASD, on the other hand, exhibited random p-spikes throughout their arm-extending movement. For typically developing individuals, these p-spikes become more organized as children develop, normally by the age of four or five. The study suggests that individuals with ASD may skip this developmental period.
Some of the parents of children with ASD also exhibited random p-spike fluctuations, similar to those of their children. This suggests that there may be a genetic component to movement normalization.
Individuals with more random p-spikes tended to have lower spoken language skills. Principal investigator Jorge V. Jose, Ph.D., professor of physics vice president of research at Indiana University, explained that p-spikes can indicate the severity of ASD. “Normally, children get more coordinated as they age, but we found that the young children with autism and the adults with autism all produced random p-spikes showing that they do not transition as they develop. We also found a correlation between the randomness of the p-spikes and the severity of the disorder”
This research was presented at the 2014 Society for Neuroscience annual meeting.
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