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NEW YORK (Reuters Health) - People who are strongly right-handed might be more vulnerable to distorted body image and eating disorders than those who are more adept at using both hands, a new study suggests.

Researchers speculate that the unusual connection might be explained by brain activity; people who consistently favor their right hand may be less able to access the body image processing centers in the brain's right hemisphere.

Other studies have found that people who are "mixed-handed" -- using their non-dominant hand for some tasks -- may have a stronger connection between the two sides of the brain. Compared with people who are strongly right-handed, they seem to have a larger corpus callosum, the bundle of nerves connecting the brain's two hemispheres.

This is relevant to body image and eating disorders because both sides of the brain appear to play a role in a person's perception of his or her own body.

What's more, there's evidence from brain-imaging research that the distorted body image associated with anorexia may be related to dysfunction in the brain's right hemisphere, explained Dr. Stephen D. Christman, a professor of psychology at the University of Toledo in Ohio and the lead author of the new study.

"So we interpret our findings of greater distortion of body image in strong right-handers as arising from their decreased access to right-hemisphere-based body image representations," Christman told Reuters Health.

The findings, which are published in International Journal of Eating Disorders, are based on assessments of two groups of college students. The first group, composed of 135 men and women, answered questions about their body image perceptions and beliefs about body appearance in general.

Overall, the researchers found, students who were strongly right-handed were more likely to have a distorted perception of their weight than those who were mixed-handed. (Because few people are exclusively left-handed, the study only compared strongly right-handed and mixed-handed individuals.)

Among the 185 students in the second group, strong right-handers generally scored higher on a measure of eating disorder risk factors, including body dissatisfaction and a strong desire for thinness.

The findings echo earlier research by Christman and his colleagues that found that people who are strongly right-handed tend to have poorer recollection of childhood memories and other life events -- another effect they suspect is related to the smaller corpus callosum and less interaction between the two brain hemispheres.

However, if it's true that strong right-handers are more susceptible to body image distortion, it's not clear what could be done with that information, according to Christman. People can't change the strength of their handedness, he noted, or increase the size of the brain's corpus callosum.

However, he noted, there's a psychotherapy technique called Eye Movement Desensitization and Reprocessing that is used to treat post-traumatic stress disorder. It involves side-to-side eye movements that, Christman and his colleagues hypothesize, might enhance the interaction between the two sides of the brain.

This hints that the therapy could help treat body image disturbances in people with eating disorders, according to Christman. For now, though, that remains speculation.

SOURCE: International Journal of Eating Disorders, April 2007.

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