More recently, Fiori has found that friends, rather than family, may provide the best ladder out of the well of loneliness.
Why should friends matter more than family? Again, she says, it's the perception that matters.
Family members are there because they have to be, she says. It's in their job description.
But friends don't have to be there for you. The fact that they are, she has found, makes their contribution rich indeed.
Making friends is not always easy, and it can be especially difficult for elders. People may not tend to think of co-workers as friends, but they provide a social network that is lost after retiring. There are fewer opportunities to meet people, and that is especially true when one spouse dies.
Some research shows that men are particularly vulnerable. The wife is the "kin-keeper," as Fiori puts it, and when she's gone there's no one there to get the family together, and no one to arrange parties with friends. Isolation and loneliness take control.
Researchers suggest various ways to avoid that, like joining a club, or getting active in a hobby that involves other people. But there is some evidence that loneliness is not something we can all escape.
Psychologists at the University of Chicago found evidence that loneliness may be at least partly genetic. By studying 8,387 sets of identical and fraternal twins in the Netherlands, they found that half the identical twins, and only a fourth of the fraternal twins, shared similar characteristics of loneliness. That strongly suggests that feeling lonely is largely dictated by heredity.
"An interesting implication of this research is that feelings of loneliness may reflect an innate emotional response to stimulus conditions over which an individual may have little or no control," the researchers concluded. In other words, for at least some people, making friends may help, but it may not necessarily chase away loneliness.
Furthermore, the research indicates that the effect of heredity on loneliness doesn't diminish as we age.
So not only are our genes driving us toward loneliness, events beyond our control also tend to drive us into our own isolated world. Friends and family members die. Health deteriorates. Money seems in short supply.
As the old saying goes, growing old isn't for sissies.
But all the research points to at least one conclusion. It's best not to try it alone.