John Cacioppo explains how loneliness differs from anxiety and depression.

Cacioppo:    Loneliness is the feeling that you’re socially isolated.  It’s related to being physically isolated from other people, but it’s not the same thing.  One can be lonely in a marriage, lonely in a family, they can be lonely in a crowd.  So we found it isn’t the number of contacts or the frequency of interaction with other people, it’s the quality of those interactions.  Freshmen who have gone to college find themselves among many, many other people, lots of social activities, they go to mixers, and they look around, everyone else is talking with other people and they’re sitting there, all alone in their head.  And so, that actually can make their feeling of isolation greater for that moment.  So, being around other people is not what makes people less lonely, it’s feeling connected to other people that makes them feel less lonely.

Question: How does loneliness differ from anxiety or depression?

Cacioppo:    Traditionally, loneliness and depression, loneliness and anxiety were treated as very similar constructs, so much so that one of the common measures of depression that’s used in epidemiology has, as one of the questions, “Do you feel lonely?”  Our own research and research of others have looked at whether loneliness and depression are the same thing and we find them to be separate constructs.  They’re separate mental states.  Our longitudinal research and our experimental research has shown that loneliness leads to increased depressive symptomatology.  So, if…  No matter how depressed you are today, if you’re feeling lonely today, you will be more depressed a year from now, above and beyond which our level of depression today would predict because of the loneliness.  We also find that depression lead you to withdrawal, so a difference in depression and loneliness is loneliness makes you want to reach out and contact other people, be a part of that group, be a part of that relationship.  Depression is associated with depressed affect but also with lethargy, kind of this withdrawal from others.  And, indeed, with depression, we find, over time, people do withdraw from others and that withdrawal and in the increased stress associated with that leads them to feel lonelier.  So, you have this pernicious feedback loop, the lonelier they are, the more depressed they’d become.  The depressed they are, the more they withdraw and the lonelier they become.  If you look at those two effects, though, the effect of loneliness and depression is stronger than the effect of depression on loneliness.  People can be depressed for other reasons and feeling lonely, but many people who go in to seek treatment for depression, at the root of the problem is their feeling of disconnection and isolation, and unless that’s treated, the depression or any attempt to fix that is really just kind of a transient band aid.  It’s not getting at the root problem.

Question: What are the symptoms of loneliness?

Cacioppo:    The measurement of loneliness is somewhat not obvious.  People know that they feel isolated.  They feel disconnected.  They don’t have others on whom they can rely or talk, but it’s mostly they don’t have a confidante.  They don’t have anyone who affirms who they are.  That’s part of it.  Now, if you ask people do they feel lonely, there tends to be this stigma associated with loneliness, I think, or research has suggested that it’s inappropriate stigma, but there’s nevertheless this stigma associated with loneliness.  So, people under report.  If you ask them, “Do you feel lonely?” they under report.  But if you ask them, are there others on whom they can rely, to whom they can relate and whom they can confide, that’s when you start to see people admitting this feeling of isolation.  There’s also this sense in which they don’t have a collective identity.  So, immediately after 9/11, when we all survived that tragedy, it made being an American salient.  That’s a social identity.  But, if you noticed, in this country, journalists were writing about the harmony, the goodwill that existed in America.  That was a step up of what had been felt a week before 9/11.  That’s part of being connected, and so, a lonely individual is also [absent at that] social identity and it may be in the form of feeling like you’re an American after a tragedy or [you might be a] Chicago Cubs or New York Yankee’s fan, these kinds of identity is a part of how we are connected to other individuals and other groups, and lonely individuals tend to lack those as well.

Question: How do we avoid being lonely?

Cacioppo:    There are several secrets to overcoming or avoiding loneliness.  I like to use the analog of hunger.  Loneliness has evolved because it has a very adaptive purpose.  We are fundamentally social species, but we need some signal when that important need isn’t being met, very much like hunger.  We need a reasonable level of blood sugar, else we don’t have the metabolic resources, the energy to pursue foraging and other activities.  When we start to have lower blood sugar levels, we become hungry, and that’s a signal that we should find food and eat and refuel.  If we ignore that hunger signal, if we think that somehow that’s stigmatizing, and so we simply persist in not pursuing any food and ignoring that signal, we can become so depleted of energy that we’re no longer able to seek that food.  So it can become chronic and deadly.  Loneliness is very much like that, and instead of sustaining us with calories, it sustains us with connections.  In evolutionary times, we were not able to fend off large, wild beasts very well, as individuals with a stick, nor were we able to take care of our offspring who have the longest period of abject dependency of any species, if we were simply solitary animals.  We are able to achieve reproduction, survival and/or offspring survival long enough so that they too reproduce because we acted as a group, as a collective.  So, finding yourself ostracized or separated from that group is a threatening, dangerous circumstance.  Recognizing that you’re also going to understand how the feeling of loneliness, the pain of loneliness, the threat that’s associated with this loneliness is a signal, very much like hunger, but it’s there to cue the need to reconnect, to protect that part of our existence, and if we respond to it as that cue, then it can be very healthy.  If you don’t respond to that cue, then you can fall into the grips of chronic loneliness, and that has, as I suggested, very deleterious mental, psychological effects, but also physiological effects.