A crippling disorder that is difficult to treat strikes nearly everyone at various stages in life, and complications can contribute to heart disease, stress, emotional instability and even death. It is particularly ruthless when it hits elders, as well as adolescents, and in some cases it may be nearly impossible to cure.
It's called "loneliness."
A growing body of research reveals that for many people, lonely is normal, especially during the holiday season. It can be brought on by a number of causes:
Most of us are lonely from time to time, but "the prevalence of loneliness may be different for different ages," says Katherine Fiori, who is just finishing up her work toward a doctorate in developmental psychology at the University of Michigan in Ann Arbor. "It may be particularly prevalent among older adults, and among adolescents, and at certain points in the lifespan when people are going through different changes, like retirement," she says.
"But the prevalence and types of loneliness may differ by age."
Nowhere is that more apparent than among the elderly, according to Fiori's research. A close personal relationship with her grandparents led her into a field that many younger researchers shun, gerontology.
She was especially close to her grandmother, and when she died, Fiori says, the impact on her grandfather was very hard to watch.
"Watching my grandfather go through the process of grieving made me particularly interested in loneliness," she says.
That helped focus her attention on research she carried out a few years ago while spending a year at the Max Planck Institute for Human Development in Berlin. While there, she had access to a rich body of work called the Berlin Aging Study. For more than a decade now researchers there have been interviewing participants in the study, all of whom were at least 70 years old.
They began with 516 seniors, Fiori says. Fewer than 50 are still alive.
Combing through those interviews, she found some disturbing numbers.
Most of those senior citizens -- nearly 60 percent -- described themselves as lonely. Some felt socially isolated. Others felt emotionally lonely. Some felt both socially and emotionally out of the loop.
Surprisingly, those with the largest number of friends were among those who were hardest hit by loneliness. They found themselves not only alone in a crowd, but alone in an aging crowd. Furthermore, while they may have had many friends, they described themselves as more depressed and less satisfied with their lives than those with fewer friends.
The reason, Fiori concludes, is that success does not lie in numbers. Instead, it's how the relationship is perceived that matters.
"People can have large social networks and still feel really lonely," she says. "Even if they have a lot of people around them, they may not feel they have people they can turn to, or people they feel close to. It's really a perception."
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.