More than half of kids and adolescents with autism are physically aggressive and new research suggests that sleep, sensory and other underlying issues may be responsible for the behaviors.

In a study of 1,584 children with autism ages 2 to 17, researchers report this month in the journal Research in Autism Spectrum Disorders that about 53 percent were aggressive.

The report is based on an assessment of children enrolled in the Autism Treatment Network, a nationwide network of care centers for kids with the developmental disorder. Parents were asked whether or not their child intentionally hit or bit others or demonstrated similar types of physical aggression. Then, researchers analyzed other clinical assessments and parent-submitted data on the children to identify trends differentiating those who were aggressive from those who were not.

While the race or gender of a child did not appear to impact their odds of displaying challenging behaviors, the study found that other characteristics did. Specifically, children were most likely to lash out physically if they engaged in self-injury or had sleep or sensory problems.

Younger kids were also more likely to be aggressive than older ones, researchers found, though they said the problem behaviors remained present at an “alarming rate” in the teenage years, with nearly half of adolescents in the study exhibiting aggression.

Other factors including the education level of a child’s caregiver and the presence of gastrointestinal issues, communication and social skills deficits were also linked to the presence of aggression, but to a lesser degree.

“Overall, the results of the current study indicate that aggression is markedly prevalent among children and adolescents with ASD, and that some sets of co-occurring problems may place individuals at risk for aggression,” wrote Micah Mazurek of the University of Missouri and her colleagues in the study. “The results suggest that increased attention should be given to the identification and treatment of sleep problems, self-injury and sensory problems, in particular.”

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