A new study shows the stress of losing an adult son does not contribute to higher death rates among parents, raising questions about the relationship between stress and the body's defenses and overall well-being.

The new Israeli study, published in the New England Journal of Medicine, tracked for a period of 10 years the deaths among parents of all 2,518 soliders who were killed during the Yom Kippur War in 1973.The mortality rate of parents of 1,128 men, aged 18 to 30, who had died in accidents between 1971 and 1975, was also analyzed for a decade.

The results show that during the 10-year followup period, no more deaths occurred among the beareaved parents compared with the general population, the study said.

The study said parents who were divorced or widowed at the time they lost a son did have slightly higher mortality rates, indicating the important support role spouses play during the time of mourning.

The study did not examine the effect of a daughter's death.

The study raises questions about grief as a factor that can lead to death, the authors of the study said.

The authors, led by Itzhak Levav of Hebrew University in Jerusalem, said there are few studies examining the effect of a child's death on the health of his or her parents.

Many investigators, however, have researched the effects of a spouse's death. Some studies show higher death rates among the surviving spouses while others show little or no effect, Levav's group said.

Research indicates severe emotional stress can trigger disruptions in heart function leading to death. Years after a loved one has died, research suggests that stress and depression, as well as lack of social and marital support, may lead to lower immune function.