Ambidextrous kids more prone to mental issues

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Ambidextrous kids more prone to mental issues

Ease with both hands also tied to language, academic problems, study says

By Jeanna Bryner

updated 2:35 p.m. ET, Mon., Jan. 25, 2010

Children who are ambidextrous, using either hand with the same ease, may be more

likely to have mental health, language and academic problems than their peers,

according to a new study.

The researchers say the findings may help teachers and health professionals

identify children who are particularly at risk of developing these problems.

The researchers aren't sure what is behind this link, though they suggest

differences in the brain between ambidextrous individuals and those who have a

dominant hand may play a role. In fact, scientists aren't sure why some people

can use both hands equally well (with no dominant hand), a skill also known as

mixed-handedness.

They also warn that since the phenomenon is rare, with just one out of every 100

people being mixed-handed, the study only focused on a small group of these

individuals.

" But our results are statistically and clinically significant, " said lead

researcher Alina of the Imperial College London. " That said, our

results should not be taken to mean that all children who are mixed-handed will

have problems at school or develop ADHD. We found that mixed-handed children and

adolescents were at a higher risk of having certain problems, but we'd like to

stress that most of the mixed-handed children we followed didn't have any of

these difficulties. "

The study is detailed in the most recent issue of the journal Pediatrics.

Handedness and language

The study involved nearly 8,000 children in Northern Finland, 87 of whom were

mixed-handed, who completed questionnaires at ages 7 and 8, and again at 15 and

16. Since 90 percent of the population is right-handed, they compared both

ambidextrous and left-handed individuals to this norm — right-handedness.

Parents and teachers also completed questionnaires regarding the 8-year-olds'

language abilities, scholastic performance and behavior. Teachers specifically

reported whether children had problems with reading, writing or mathematics, and

rated academic performance as below average, average or above average.

For all variables except math, left-handed individuals showed no problems

compared with their right-handed peers. For math, at ages 7 and 8, left-handers

were 30 percent more likely to have problems compared with right-handers. And

ambidextrous children were nearly 90 percent more likely than right-handers to

have these math problems.

Results also showed the ambidextrous 7 and 8-olds were twice as likely as their

right-handed peers to have language difficulties and to perform poorly in

school.

By age 15 or 16, mixed-handed adolescents were also at twice the risk of having

symptoms of attention deficit/hyperactivity disorder (ADHD). And those

ambidextrous teens with ADHD had more severe symptoms than their right-handed

counterparts.

The mixed-handed teens reported having greater difficulties with language than

left- or right-handed peers.

Brain hemisphere in charge

Here's how the link might work: Scientists know handedness is linked to the

hemispheres of the brain. For instance, studies have shown that in right-handed

individuals, the brain's left hemisphere is more dominant.

" Handedness is seen as a proxy for how the brain is functioning, and it's not a

perfect measurement. A more accurate method would be to use fMRI [magnetic

resonance imaging] scanning, but this isn't possible in a large-scale study, "

told LiveScience.

" All we can say from this is that they have an atypical brain lateralization;

that just means the brain circuitry and function is likely to differ from the

normal pattern, " seen in right-handed individuals, she said.

And the right hemisphere, for instance, might not function in the same way for

ambidextrous individuals as it does for right-handed individuals,

said. That could explain the association with ADHD, as one study has shown that

those with ADHD have difficulties processing information normally processed in

the right hemisphere of the brain.

The results would likely extend beyond Finland, the researchers say. " There is

no reason to believe that American children would behave in any other way as the

children in this study, " said.

The research was funded by the Academy of Finland, the Sigrid Juselius

Foundation, Thule Institute, University of Oulu, and the National Institute of

Mental Health. received support from VINNMER.

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