Lefties are used to getting the short end of the stick—from having to work around right-handed school desks, computer mice and pretty much anything else that requires a dominant hand to being regarded as an aberration that needs to be “fixed” to even being looked upon with fear (because there happens to be a very old and extremely lengthy list of folklore and left-handed superstitions all pointing to the left side equalling bad luck).
Research on south paws hasn’t exactly turned up the best of news, either. The Wall Street Journal, in an examination of several different studies, found that left-handed people really do have bad luck—if you consider having a higher risk for brain and developmental disorders as ”bad luck,” that is.
Lefties make up about 10% of the population and further 1% are mixed-handed (neither right- nor left-hand is dominant— either hand may be used for different daily tasks). But studies have shown that 20% of schizophrenia sufferers are left-handed, and that links exist between being a lefty and dyslexia, ADHD, and language development issues. These links are even more pronounced for people with mixed-handedness.
While there is a 25% chance that genetics will play a part in defining a person’s handedness (the dominant-side hand) , it is environmental factors that play the biggest part in making a lefty—especially by stress experienced in the womb. Older mothers and low birth weights are also more likely to produce left-handed children. One Danish study found that women who experienced multiple traumas in their third trimester were more than three times as likely to have a child with mixed-handedness. Cortisol, a stress hormone able to cross the placental barrier, may affect fetal brain development and be the reason why left-handed people’s brain hemispheres process information differently than right-handed people’s.
There are positives to being left-handed, of course—research shows that lefties are better at divergent thinking, an element of creativity that allows one to develop new concepts from existing facts, being left-handed can give an edge to athletes in certain sports, like tennis, baseball, and fencing, and it can be a source of pride in our individualistic society. It is often noted, as well, that there have been six left-handed U.S. presidents out of the last 12, Barack Obama, Harry Truman and a mixed-handed Ronald Reagan included.
The link between stresses in the womb, how that affects the “wiring” of the brain, and how that wiring affects psychiatric and developmental disorders is the crux of these studies—being left-handed, especially mixed-handed, appears to be an indication of that different wiring. What this means for parents is that doctors could begin to view being left- or mixed-handed as a risk factor for these disorders—which could help children who experience difficulties at school or who have behavioral problems get evaluations more quickly. And earlier diagnoses will hopefully get some children children the help they need sooner.
File under “anecdotal evidence”: I have a son with ADHD who is also mixed-handed. I can also verify that I had a lot of stress during my third trimester. Coincidence? There isn’t a genetic link for lefties in our families, so I doubt it. Do you have anecdotal evidence of any of these links, too? Do you think this research, if it gains enough attention in the media, could become a source of teasing or lead to stereotyping by teachers left-handed children?
Photo Credit: © Solaria – Fotolia.com
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