The researchers suspect that older people who have few social ties may not be getting the care they need. No one is urging them to eat right or take their medicine, and in a crisis no one is there to help.
"There are plenty of people who are socially isolated but who are perfectly happy with that," Steptoe says. "But even then we should be trying to make sure there's enough contacts with them so that if something does go wrong . . . they're going to be advised and supported." Even those who are content to be alone, he says, should have some regular contact with other people who can encourage and check on them.
Other researchers praise the new work as rigorous and well-controlled. But they say it's far from clear that social isolation, not loneliness, is always the real culprit when it comes to increased mortality.
Other studies, including an analysis of older Americans led by John Cacioppo, a psychology professor at the University of Chicago, have shown a link between loneliness and a higher death rate. Cacioppo suspects that the discrepancy between his study and the new research could lie with cultural differences between Steptoe's British subjects and Americans. "The culture of the stiff upper lip may mean people are answering somewhat differently . . . than they do in America," he says, adding that Britons and Americans may define friends differently, too.
Health psychologist Bert Uchino, of the University of Utah, lauds the new study for its large sample size and its direct comparison of social isolation and loneliness, but he says that researchers are still far from understanding how those two factors affect one another and other health-related behaviors.
"They've done a really good study here," Uchino says. "I just don't think it's going to be the final word on the issue."