Loneliness makes stress even more unhealthy
Lonely people live less long than people with many social contacts. Loneliness is unhealthy, and researchers at Ohio State University may have discovered why. Loneliness increases the negative effect of stress. Stress exacerbates inflammatory processes, and loneliness boosts this.
Inflammatory processes are useful. The immune system uses them to clear up damaged tissue and to kill pathogens. But too much inflammation is anything but healthy. There are even scientists who describe aging as a cascade of inflammatory processes.
When inflammation takes place the immune cells communicate with the help of interleukins such as Interleukin-1-beta, Interleukin-6 and Tumor Necrosis Factor-alpha [spatial structure on right].
The researchers got healthy subjects to make a speech in front of the camera, in which they had to say why they were suitable for an imaginary job vacancy. That caused stress. The researchers examined immune cells in the subjects' blood just after they'd made the speech, 45 minutes later and again after 2 hours, and looked at how many inflammation-promoting interleukins the immune cells made.
The researchers used questionnaires to determine whether the subjects were lonely. The figure below shows that the immune cells of the lonely subjects produced more TNF-alpha than those of the subjects who were not lonely.
The researchers repeated the procedure with a group of women who had survived breast cancer. Cancer is associated with high levels of chronic stress, and the researchers wanted to know whether loneliness also influences the stress response in the women cancer survivors. And this was indeed the case, as you can see below.
"In sum, loneliness was linked to exaggerated proinflammatory cytokine production following an acute stressor, reflecting a proinflammatory phenotype among lonely individuals", the researchers write. "The current study demonstrates that loneliness has immune consequences and provides a glimpse into the pathways through which social relationships can impact health and well-being."
Psychol Sci. 2013 Jul 1;24(7):1089-97.
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