ISLAMABAD: Researchers links loneliness to a number of dysfunctional immune responses, suggesting that being lonely has the potential to harm overall health.

According to the research, people who were more lonely showed signs of elevated latent herpes virus reactivation and produced more inflammation-related proteins in response to acute stress than people who felt more socially connected.

These proteins signal the presence of inflammation, and chronic inflammation is linked to numerous conditions, including coronary heart disease, Type 2 diabetes, arthritis and Alzheimer's disease, as well as the frailty and functional decline that can accompany aging.

Reactivation of a latent herpes virus is known to be associated with stress, suggesting that loneliness functions as a chronic stressor that triggers a poorly controlled immune response.

“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 postdoctoral fellow at the Institute for Behavioral Medicine Research at Ohio State University and lead author of the research.

The researchers measured loneliness in all studies using the UCLA Loneliness Scale, a questionnaire that assesses perceptions of social isolation and loneliness. They first sought to obtain a snapshot of immune system behavior related to loneliness by gauging levels of antibodies in the blood that are produced when herpes viruses are reactivated.

Lonelier participants had higher levels of antibodies against cytomegalovirus than did the less lonely ones, and those higher antibody levels were related to more pain, depression and fatigue symptoms. No difference was seen in Epstein-Barr virus antibody levels, possibly because this reactivation is linked to age and many of these participants were somewhat older, meaning reactivation related to loneliness would be difficult to detect, Jaremka explained.

Previous research has suggested that stress can promote reactivation of these viruses, also resulting in elevated antibody titers.

“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 an additional 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.

Baseline blood samples were taken from all participants, who were then subjected to stress. Researchers followed by stimulating the participants' immune systems with lipopolysaccharide, a compound found on bacterial cell walls that is known to trigger an immune response.

In both populations, those who were lonelier produced significantly higher levels of a cytokine called interleukin-6, or IL-6, in response to acute stress than did participants who were more socially connected. Levels of another cytokine, tumor necrosis factor-alpha, also rose more dramatically in lonelier participants than in less lonely participants, but the findings were significant by statistical standards in only one study group, the healthy adults.

When the scientists controlled for a number of factors, including sleep quality, age and general health measures, the results were the same.

“We saw consistency in the sense that more lonely people in both studies had more inflammation than less lonely people,” researcher said.