Scientists have found that answer to why the risk of dying increases among widows and widowers following their spouses' death.
They believe that the so-called widowhood effect could be caused by the combined effects of stress and age-related changes in the immune system.
Janet Lord, an immunologist at the University of Birmingham, UK, has found that increased cortisol levels caused by stressful events such as bereavement worsen the situation.
Lord's team showed that in these people, white blood cells called neutrophils - a first line of defence against pathogenic bacteria - were less potent . Neutophils are developed when people have higher blood cortisol to DHEAS ratios.
While cortisol dampens immune responses, DHEAS (Dehydroepiandrosterone sulphate) boosts them. When activated, neutrophils unleash a range of toxic molecules that kill pathogens. Now Lord's team has demonstrated that the presence of DHEAS causes neutrophils to produce one of their more lethal compounds, super oxide.
"When your cortisol is high, when you're in a stressed situation, that's when the lack of DHEAS will be important," New Scientist quoted Lord as saying.
The team plans to give supplements of a chemical closely related to DHEAS to people for three months after hip fractures to see if it increases neutrophil function.