Aging Well

Loneliness Can Cause Illness in Older Adults

For older adults, perceived social isolation is a major health risk that can increase the risk of premature death by 14 percent, according to research done at the University of Chicago and published November 23rd 2015 in theProceedings of the National Academy of Sciences

A release from the university notes that researchers have long known the dangers of loneliness, but the cellular mechanisms by which loneliness causes adverse health outcomes have not been well understood. The University of Chicago team, including psychologist and leading loneliness expert John Cacioppo, has now shed new light on how loneliness triggers physiological responses that can ultimately make us sick. The paper shows that loneliness leads to fight-or-flight stress signaling, which can ultimately affect the production of white blood cells.

Along with Cacioppo, Steven W. Cole of UCLA and John P. Capitanio of the California National Primate Research Center at the University of California, Davis examined loneliness in both humans and rhesus macaques, a highly social primate species.

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. But the study also revealed several important new pieces of information about loneliness’ effect on the body.

First, the researchers found that loneliness predicted future CTRA gene expression measured a year or more later. Interestingly, CTRA gene expression also predicted loneliness measured a year or more later. Leukocyte gene expression and loneliness appear to have a reciprocal relationship, suggesting that each can help propagate the other over time. These results were specific to loneliness and could not be explained by depression, stress or social support.

Next, the team investigated the cellular processes linking social experience to CTRA gene expression in rhesus macaque monkeys at the California National Primate Research Center, which had been behaviorally classified as high in perceived social isolation. Like the lonely humans, the “lonely like” monkeys showed higher CTRA activity. They also showed higher levels of the fight-or-flight neurotransmitter, norepinephrine.


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