Being left-handed is not a hazard to your health after all, says a study that disputes an earlier report suggesting southpaws were at risk of dying up to 14 years sooner than righties.
Scientists at the National Institutes of Health and Harvard University examined the rates of death among elderly people in East Boston, Mass., and found that left-handed people were at no more risk of dying early than right-handed people.Dr. Jack M. Guralnik of the National Institute of Aging, a part of the NIH, said the data came from a six-year community study that included 3,774 people 65 or older in East Boston. All deaths were recorded and analyzed.
Although the study was conducted for other reasons, Guralnik said Thursday, the information collected included whether the subjects were left-handed or right-handed. That enabled the researchers to test a theory that southpaws die younger than do right-handed people, he said.
"Over the six-year period, the death rate was 32.2 percent among right-handers and 33.8 percent for left-handers," not a statistically significant difference, Guralnik said.
The preferred hand, or laterality, of the people was established by asking which hand was used to write and to cut with scissors.
Guralnik said 9.1 percent of the men and 5.8 percent of the women in the study were left-handed.
He said the East Boston study was the most accurate way to find any differences in the rate of deaths between left- and right-handers because it compares population groups of the same age. Also, he said, laterality was established by direct interview with the subjects, not by - pardon the expression - secondhand information.
A 1980 study first raised the possibility that being left-handed could mean an earlier death. That study found that there was a higher percentage of lefties among the young. It claimed that the mean age of death for lefties was 58, while for righties it was 72, a 14-year difference.
Guralnik said this study was flawed because the groups studied contained a higher proportion of young left-handers.
"Mean age of death is not a good thing to use," he said. "If you have two populations that are very different in age, you would expect the younger population to have a lower mean age of death. It may simply relate to the fact that the population was younger."
A study published in 1991 found that left-handed professional baseball players lived for an average of 64 years, about eight months less than righties.
Other researchers attacked the baseball study because it was based on how the players batted and threw, which they argued could have been based on training, not true laterality.