While it could be a chance finding and the evidence is far from conclusive, numerous reports have associated left-handedness with various disorders and, in general, a shorter life span, Dutch researchers note in their report in the journal Epidemiology.

"Left-handers are reported to be underrepresented in the older age groups, although such findings are still much debated," write Dr. Made K. Ramadhani and colleagues from University Medical Center Utrecht. It is estimated that about 1 in 10 people are lefties.

Among 12,178 middle-aged Dutch women the researchers followed for nearly 13 years, 252 died.

When left-handed women were compared with the other women, and the data were adjusted for a number of potentially confounding factors, lefties had a 40 percent higher risk of dying from any cause, a 70 percent higher risk of dying from cancer, and a 30 percent higher risk of dying from diseases of the circulatory system.

Left-handed women also had a 2-fold increased risk of dying from breast cancer, close to a 5-fold increased risk of dying from colorectal cancer, and more than a 3-fold higher risk of cerebrovascular mortality.

The underlying mechanisms remain elusive, although genetics and environmental factors may be involved, Ramadhani and colleagues suggest. Much of the research into handedness and mortality has been fueled by the hypothesis that left-handedness is the result of an insult suffered during prenatal life, which ultimately leads to the early death.

The author of a commentary, Dr. Olga Basso, who is left-handed, is highly skeptical, in general, of research relating disease and death with handedness. "I am not alone in thinking that the literature on handedness suffers from a number of ills," regardless of the putative illnesses seen in those who are left-handed, she notes.

"Having successfully dodged a number of disorders," adds Basso, "I doubt that my left hand is prematurely pulling me toward my grave."

Basso is with National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina.