June Carter Cash and Johnny Cash were devoted to each other

A University of Glasgow study looked at over 4,000 couples found bereavement did increase the risk a widow or widower would die.

Couples who seemed unable to live without one another include singers Johnny Cash and June Carter Cash, who died within months of each other.

Heart experts said people who lost a partner often adopted unhealthy habits such as smoking and poor diet.

Bereavement impact

The Scottish study, published in the Journal of Epidemiology and Community Health, looked at married couples aged 45 to 64 when the study began in the early 1970s.

"It is really about how we cope with the bereavement, rather than the process itself

Cathy Ross, British Heart Foundation

The researchers logged when one partner died, and then looked at the mortality incidence in their partners until 2004.

More than twice the number of women than men were bereaved during the follow-up period.

There was a high risk of death from any cause in the first six months after a spouse died, and a higher risk of heart disorders in the first five years.

The link remained even when individual risk factors, such as smoking and blood pressure, were taken into account.

Writing in the journal, the researchers led by Dr Carole Heart, said: "We have shown that bereavement does have an impact on mortality risk, in addition to that of individual risk factors - which had a fairly small influence - and that the effects are persistent."

Stewart Wilson, of the counselling charity Cruse Bereavement Care, said: "When a couple have been together a long time, the incidence of long-term survival is relatively low for the other partner."

Cathy Ross, of the British Heart Foundation, said the common ways of coping with the death of a loved one often led to health problems.

"Some people will smoke more, other people may drink more and they tend not to eat - or to eat really badly.

"It is really about how we cope with the bereavement, rather than the process itself."

June Carter Cash died aged 73 in May 2003 after heart surgery. Four months later, Johnny Cash died from complications of diabetes aged 71.

And former prime minister James Callaghan died aged 92 in 1995 just 10 days after Audrey, his wife of 67 years.