The study is published in the Jan. 25 online issue of Pediatrics.
About 1 percent of children in the study were identified by their parents as being mixed-handed, while about 8 percent of kids were left-handed. The researchers found no association with being left-handed and any of the scholastic or mental health impairments.
One explanation for why mixed-handed children may be more prone to language difficulties and ADHD is because being ambidextrous is a proxy for atypical cerebral lateralization, or differences in the structure and function of the brain.
The brain is normally specialized, Rodriguez explained, with the left hemisphere of the brain dominant in right-handed people. Mixed-handed people, however, have differences in the typical dominance pattern of the brain.
Prior research has suggested that children with dyslexia and with ADHD have disturbances in the right hemisphere.
Though the study is interesting, it's probably of limited use as a diagnostic tool, said Dr. Andrew Adesman, chief of developmental and behavioral pediatrics at Schneider Children's Hospital in New Hyde Park, N.Y.
Most of the mixed-handed children in the study did not have ADHD, scholastic difficulties or any other mental health issues, he noted. And the majority of children who had ADHD or problems at school were not mixed-handed.
Still, it's an area that merits further research, Adesman said.
"Handedness has a relationship to brain development, and brain development has a relationship to ADHD and dyslexia," Adesman said. "The data support the idea that there seems to be an increased association between mixed-handedness and learning-attentional problems."
CHADD (Children and Adults with Attention Deficit/H
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