WHY do some widows and widowers quickly follow their spouses to the grave? It seems the so-called widowhood effect could be caused by the combined effects of stress and age-related changes in the immune system.
Previous studies found that among elderly men and women the risk of dying within three months of being widowed increases between 30 and 90 per cent. It had been suggested that this might be connected with changes in the immune system, yet exactly how was unclear.
Now new research has identified some of those changes, and shown that increased cortisol levels caused by stressful events such as bereavement worsen the situation.
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Dehydroepiandrosterone sulphate, or DHEAS, is best known as an intermediary of sex hormones like testosterone and oestrogen, yet it also has a role in the immune system. While cortisol dampens immune responses, DHEAS boosts them. Levels of DHEAS usually peak and begin declining when people are in their thirties.
, an immunologist at the University of Birmingham, UK, has previously found that people over the age of 66 who had a hip fracture had higher blood cortisol to DHEAS ratios than similarly aged people without fractures. Those with the largest disparities were most likely to develop bacterial infections, and Lord鈥檚 team showed that in these people, white blood cells called neutrophils 鈥� a first line of defence against pathogenic bacteria 鈥� were less potent (Aging Cell, ).
When activated, neutrophils unleash a range of toxic molecules that kill pathogens. Now Lord鈥檚 team has demonstrated that the presence of DHEAS causes neutrophils to produce one of their more lethal compounds, superoxide (Molecular Endocrinology, ).
In another ongoing but as yet unpublished study, Lord studied widows and widowers aged 65 and over who had been bereaved during the previous two months. Preliminary results suggest they have higher cortisol to DHEAS ratios and lower neutrophil function than people who have not recently lost their partner. 鈥淲hen your cortisol is high, when you鈥檙e in a stressed situation, that鈥檚 when the lack of DHEAS will be important,鈥� she says. Lord鈥檚 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.
, at the University of Texas Health Science Center in San Antonio, says the new work is the 鈥渃learest, cleanest鈥� proof that DHEAS can have a direct immune system effect. However, he is yet to be convinced that its drop in old age compromises the immune system, even under stress.
