Compared with right-handed children, kids who can write with both hands may be twice as likely to have language and learning struggles, and to exhibit symptoms of Attention Deficit Hyperactivity Disorder (ADHD), according to new research published in the journal Pediatrics. This latest study, led by Dr. Alina Rodriguez from the Department of Epidemiology and Public Health at Imperial College London, adds to previous research into the associations between left-, right- and mixed-handedness and brain function, including studies that have suggested a link between ambidexterity and dyslexia. The researchers write that, together with this latest study, research in this area may indicate “possible interconnection among mixed-handedness, neurotransmitter dysfunction in the right hemisphere and ADHD symptoms.”
Researchers analyzed data for 7,871 Finnish children who were born in 1986 and assessed at age seven or eight, and again at age 16. At age 8, children were categorized as either left-handed, right-handed, or mixed-handed, according to their parents. In total, 1.1% of children (87) included in the study were ambidextrous, roughly the same proportion as in the general population. At age eight, language skills and behavioral problems were assessed by questionnaires given to parents and teachers. At 16, the study participants also filled out questionnaires, in addition to responses recorded from parents and teachers. ADHD symptoms were also assessed at age 16 according to a scale taken from the Diagnostic and Statistical Manual of Mental Disorders-IV.
The researchers found that, at age eight, children who were ambidextrous were twice as likely to have trouble with language skills and to struggle with academics, compared with their right-handed peers. When the study participants were assessed again as teenagers, researchers found that mixed-handed participants were twice as likely to exhibit symptoms of ADHD, and even compared with right-handers who had ADHD, ambidextrous kids were more likely to have severe symptoms of the disorder. Additionally, as adolescents, language struggles were more prevalent among those who were mixed-handed, compared with either left-handed or right-handed peers.
Obviously, as the researchers stress, these findings do not mean that every ambidextrous child will develop learning disabilities or ADHD, but they do suggest that mixed-handed kids may be at higher risk for these problems. Existing research indicates the connection between handedness and brain hemispheres—i.e, that the left hemisphere is more dominant among right-handed people—and has inspired hypotheses about the differing patterns of hemispheric dominance in people who are ambidextrous. Yet these latest findings highlight the need for more research in this area, Rodriguez and colleagues argue, because a better understanding of the brain mechanisms linking handedness with learning and language skills could not only yield a clearer understanding of conditions such as ADHD, but perhaps inspire techniques for early detection, and intervention.