Loneliness is more than a feeling: For older adults, perceived social isolation is a major health risk that can increase the risk of premature death by 14%.
Researchers have long known the dangers of loneliness, but the cellular mechanisms by which loneliness causes adverse health outcomes have not been well understood. Now a team of researchers, including the University of Chicago psychologist and leading loneliness expert John Cacioppo, has released a study shedding new light on how loneliness triggers physiological responses that can ultimately make us sick.
The paper, which appeared in the Proceedings of the National Academy of Sciences, shows that loneliness leads to fight-or-flight stress signaling, which can ultimately affect the production of white blood cells, The Independent reported.
Along with Cacioppo, the research team includes Steven W. Cole of UCLA and John P. Capitanio of the California National Primate Research Center at the University of California, Davis.
The study examined loneliness in humans and rhesus macaques, a highly social primate species. The human subjects were participants in the Chicago Health, Aging, and Social Relations Study, a longitudinal study that began in 2002 with adults aged 50-68.
Previous research from this group had identified a link between loneliness and a phenomenon they called “conserved transcriptional response to adversity” or CTRA. This response is characterized by an increased expression of genes involved in inflammation and a decreased expression of genes involved in antiviral responses. Essentially, lonely people had a less effective immune response and more inflammation than non-lonely people.
For the current study, the team examined gene expression in leukocytes, cells of the immune system that are involved in protecting the body against bacteria and viruses.
As expected, the leukocytes of lonely humans and macaques showed the effects of CTRA—an increased expression of genes involved in inflammation and a decreased expression of genes involved in antiviral responses.
