Feeling lonely can make you sick. Doctors have long known that loneliness is associated with cardiovascular problems, viral infections, and higher mortality. What they didn’t know is how this feeling begets illness. A study in the September issue of the online journal Genome Biology suggests that loneliness actually affects the very core of our bodies—our genes.
In a small population of patients, researchers surveyed more than 20,000 genes using DNA microarrays to compare how the genes of lonely and nonlonely individuals express themselves in molecular processes and, ultimately, in personal health. They found that gene expression is different at 209 sites in chronically lonely people and that many of those changes fit a pattern of elevated immune activation, inflammation, and depressed response to infection. “We now have a molecular framework for understanding the relationship between social experience and physical health,” explains the study’s lead author, Steve Cole of UCLA.
The study found that loneliness desensitizes the glucocorticoid receptors, cutting off the immune control and anti-inflammatory effects of cortisol, a stress-related hormone that also helps regulate the conversion of carbohydrates to energy. The depressed cortisol response concurs with the known effects of loneliness and provides a potential target for treatment.
This study—the first to link feelings with genomewide changes—is “in some sense groundbreaking,” says Emma Adam, an associate professor of human development and social policy at Northwestern University. “It fills in the black box.”
According to John Cacioppo, an author of the study and a psychologist from the University of Chicago, the work suggests that loneliness is a warning sign, much like physical pain. “This very process of feeling bad because of disconnection contributes to what it means to be human,” he says. “It makes us care for other people and want to reconnect when we’re disconnected.”
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