People who are socially isolated are more likely to die prematurely, regardless of underlying health problems, according to a study of the elderly British population.

The findings, published online Monday in the Proceedings of the National Academy of Sciences, showed that when mental and physical health conditions were factored out, the lack of social contact still led to early death among 6,500 men and women tracked over seven years.

"They're dying of the usual causes, but isolation has a strong influence," said an author of the study, Andrew Steptoe, an epidemiologist at University College London.

The study also appeared to diminish the role that subjective feelings of "loneliness," as opposed to the lack of social contact, may have on a person's life span. Both lead to higher mortality risks, the study noted, but the effect of feeling lonely diminishes once demographic and health factors are taken into account.

Regardless of the distinction, the study reinforces the need to increase social support for the elderly, even as it adds to debate over the intertwined effects of social contact and feelings of loneliness in old age. A similar look at retired Americans in 2012 reinforced multiple studies that link loneliness to numerous illnesses, including heart trouble and high blood pressure.

People living alone account for more than a quarter of U.S households, and the proportion of Americans who said they had no one to talk to about important matters grew from 10 percent in 1985 to 25 percent in 2004, according to authors of the British study.