International Left Handers Day in August

Left Handedness and Your Health

Girl writing with her left hand
Photography by Tera Fraley/Moment Open/Getty Images

August 13 marks the annual international left-handers day. Left handers day was established over 20 years ago, in 1992, to raise awareness of the pluses and minuses that are an inherent part of being left handed. About 10-15% of the worldwide population is left handed, and most of us who are left handed have a strong preference for using our left hand for writing and for most skill oriented, intricate tasks.


Left Handedness and Your Health

 If you ever need to see a neurologist for any reason, one of the first questions a neurologist will ask you is whether you are right handed or left handed. Because of the way our brains are wired, the medical evaluation of neurological conditions, including stroke, is largely guided by whether you are right handed or left handed.

Left Handedness and Language After a Stroke

Left handedness and language after a stroke

A stroke, in particular, is a medical illness that affects left handed stroke survivors differently than right handed stroke survivors because some of our most important brain abilities are situated almost exclusively on only the dominant or non dominant side of the brain. The dominant side of your brain corresponds to whether or you are right handed or left handed. The dominant side of your brain is the side opposite your preferred hand. So, if you are left handed, you are right brain dominant.

Why does this matter in a stroke?

Your speech center is located in the dominant side of your brain, which is opposite the hand you use. A stroke of the dominant parietal lobe or dominant temporal lobe can cause a condition called aphasia, which is a serious speech disturbance.

Left Handedness and Your Spatial Perception After a Stroke

Left handedness and your spatial perception after a stroke

 A stroke involving the sensory portion of the cerebral cortex can cause a condition called hemiagnosia, which is a deficit in awareness of one side of your body or a deficit in perception of one side of your surroundings, often referred to as hemispatial neglect. If you have a stroke in the sensory portion of your non-dominant cerebral cortex, which is on the same side as your dominant hand, this serious handicap can result.

Left Handedness and Weakness After a Stroke

Left handedness and weakness after a stroke

 The motor portion of one side of your brain controls the movements of the opposite side of your body. If you are left handed, a stroke in the right cortical or subcortical motor region of the brain can cause weakness of your dominant left arm and leg. This would be a more significant problem for you than a stroke on the left side of your brain, which would weaken your right, less coordinated, non-dominant side. You can more easily adapt to weakness on the non-dominant side of your body because most of the time, your dominant side can take over.

Benefits of Left Handedness

Benefits of left handedness

Overall, there are some unexpected benefits of being left handed, including advantages in sports and professional accomplishments. A detailed research study identified an interesting upshot of left handedness in that athletes are slower to anticipate and respond to left handed players’ moves than to right handed players’ moves.

And, population based analyses show that left handed people are more likely to attain higher educational levels, achieve better incomes and hold more prominent positions in the work setting.

The left handed advantage is interesting, but the reasons are not well understood. It may have to do with the fact that left handed people are forced to make some unnatural physical adjustments early in life, and thus subconsciously learn to better able to adapt imperfect situations. Or, it may have to do with the atypical allocation and distribution of language and spatial abilities between the two hemispheres of the brain, which might force more communication than usual between the two hemispheres.


Whatever the explanation, being left handed is worthy of a special day once a year.

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