Researchers at two British universities, the University of Surrey and Brunel University London, analyzed 30 past studies that looked into possible connections between social isolation, loneliness and physical inflammation in people aged 16 or older.
In synthesizing and reviewing those previous studies, the researchers found that social isolation was associated with the presence in the body of a substance known as C-reactive protein, which is made by the liver and is produced more frequently when there is an issue in the body causing inflammation. According to a March 5 news release by the University of Surrey, “inflammation is the body's way of signalling the immune system to heal and repair damaged tissue, as well as defending itself against viruses and bacteria.”
Prolonged inflammation in the body can damage healthy cells, tissues and organs and eventually lead to non-communicable illnesses such as cardiovascular disease. Social isolation was also associated with increased levels of the glycoprotein fibrinogen, which gets converted into fibrin-based blood clots during tissue and vascular injury.
The researchers found that the link between social isolation and physical inflammation was more likely to be seen in men than in women, suggesting that the former may respond differently to social stressors.
The findings also revealed that the link between loneliness and inflammation was not as consistent as that between social isolation and inflammation. In some cases, researchers found that loneliness correlated with cytokine IL-6, which can also be elevated in the event of inflammation, infection or some cancers.
“Our results suggest loneliness and social isolation are linked with different inflammatory markers. This shows how important it is to distinguish between loneliness and isolation, and that these terms should neither be used interchangeably nor grouped together,” Christina Victor, a professor of gerontology and public health at Brunel University London, noted in the release.
According to Dr. Kimberley Smith, a lecturer in health psychology at the University of Surrey, loneliness and social isolation can result in poorer health, but more research is needed to understand how the body’s inflammatory response system may be related to such factors.
“The evidence we examined suggests that social isolation may be linked with inflammation, but the results for a direct link between loneliness and inflammation were less convincing. We believe these results are an important first step in helping us to better understand how loneliness and social isolation may be linked with health outcomes,” Smith explained in the release.