New study suggests that loneliness can lead to to a number of dysfunctional immune responses, thus causing harm to overall health.
Researchers observed that the more lonely individuals had symptoms of high latent herpes virus reactivation than more socially-connected individuals. Also, in such loners acute stress produced more inflammation-related proteins than the others.
"It is clear from previous research that poor-quality relationships are linked to a number of health problems, including premature mortality and all sorts of other very serious health conditions. And people who are lonely clearly feel like they are in poor-quality relationships," said Lisa Jaremka, a post-doctoral fellow at the Institute for Behavioral Medicine Research at Ohio State University and lead author of the research.
"One reason this type of research is important is to understand how loneliness and relationships broadly affect health. The more we understand about the process, the more potential there is to counter those negative effects — to perhaps intervene. If we don't know the physiological processes, what are we going to do to change them?"
The results are based on a series of studies conducted with two samples: a healthy group of overweight middle-aged adults and a group of breast cancer survivors. The researchers measured loneliness in all studies using the UCLA Loneliness Scale, a questionnaire that assesses perceptions of social isolation and loneliness.
The researchers first sought to understand the immune system behaviour related to loneliness by measuring levels of antibodies in the blood that are produced when herpes viruses are reactivated.
Lonelier participants had higher levels of antibodies than did less lonely participants, and high antibody levels usually cause pain, depression and fatigue symptoms.
Previous research has suggested that stress can promote reactivation of these viruses, also resulting in elevated antibody levels.
"The same processes involved in stress and reactivation of these viruses is probably also relevant to the loneliness findings," Jaremka said. "Loneliness has been thought of in many ways as a chronic stressor – a socially painful situation that can last for quite a long time."
In another set of studies, the scientists sought to determine how loneliness affected the production of proinflammatory proteins, or cytokines, in response to stress. These studies were conducted with 144 women from the same group of breast cancer survivors and a group of 134 overweight middle-aged and older adults with no major health problems.
In both groups, those who were lonelier produced significantly higher levels of a cytokine when subjected to acute stress than did participants who were more socially connected.
"We saw consistency in the sense that more lonely people in both studies had more inflammation than less lonely people," Jaremka said.
"It's also important to remember the flip side, which is that people who feel very socially connected are experiencing more positive outcomes," she said.
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