Everyone gets lonely from time to time; perhaps you have ended a significant relationship or someone you love is far away. But being lonely all the time could actually make you sick and more vulnerable to disease.
According to UCLA researcher Steve Cole, scientists have known for several decades that people who report being socially isolated for long periods are at increased risk for some kinds of diseases. But they haven't known why. So, Cole and his colleagues surveyed some people in Chicago who were already participating in another study and asked them about their social contacts.
"[Extremely] lonely people didn't seem to have lower amounts of objective social contact with friends and family members," Cole reports. "What they said is that they felt that that contact was much less rewarding and supportive than non-lonely people did." He concludes that It seems to be the quality of social interaction, rather than the quantity, that is the chief risk factor of loneliness.
The researchers took blood samples from each of these people and ran genetic screens on all the samples. They found some genes in the lonely people functioned differently. These were genes that controlled inflammation.
"Inflammation is actually the earliest stage of an immune response," Cole explains. "When you have cells that are damaged by a cut, or as a function of just simple aging, these cells release signals that say that they're dying and the tissue around them becomes inflamed. So when you have a cut on your arm and you see that redness and swelling... that's what inflammation is."
That is a normal part of the body's maintenance, as cells die and are replaced, but Cole and his colleagues found that the lonely subjects in their study had overactive genes that produced large amounts of inflammation.
"High levels of inflammatory activity contribute to a variety of the diseases that are most prevalent killers of people in industrialized nations these days," he says. "These are diseases like heart disease, neurodegenerative disorders, certain types of cancer are also related to inflammation."
Cole said this research will help scientists determine how psychological stress contributes to these diseases This could help doctors find better ways to intervene and keep people from the adverse health effects of inflammation.
Cole's research is published in the journal Genome Biology.