Research led by scientists at the USC Dornsife College of Letters, Arts and Sciences suggests that people who feel lonely show subtle signs of faster biological aging, possibly increasing their risk for age-related diseases. The findings add to growing evidence that social connection plays a critical role in long-term health.
“Loneliness has been called a public health crisis, and our study shows it may actually accelerate the aging process at the molecular level,” said Christopher Beam, associate professor of psychology at USC Dornsife and lead author of the study.
Beam and the research team analyzed blood samples from middle-aged twins who participated in the long-running Louisville Twin Study. Using a method called epigenome-wide association, the scientists searched for chemical changes in the twins’ DNA known as methylation — modifications that can affect how genes behave without altering the genes themselves.
The researchers studied both identical and fraternal twins, focusing in part on twin pairs where one sibling felt lonelier than the other. Twins offer a unique advantage for this kind of research because they share some or all (in the case of identical twins) of their genetic and early environmental background, Beam says. This makes it easier for scientists to isolate the effects of experiences like loneliness from genetics and shared upbringing.
Although the researchers did not find any single “loneliness gene,” they did identify 25 regions of DNA that were “suggestively” linked to feeling lonely — many of them near genes involved in immune response and inflammation.
More strikingly, people who felt lonelier also scored higher on a biological aging outcome called DunedinPACE, which measures the rate at which someone’s body is wearing down over time. In other words, lonelier people appeared to be aging faster.
“Our findings don’t prove loneliness causes illness, but they do suggest it can be a major contributing factor,” Beam said.
The study is one of the first to explore the connection between loneliness and DNA methylation in adults. Beam said more research with larger and more diverse populations is needed, but this early work highlights the power of social relationships to influence health in lasting ways.
“If we can understand more of the biology of loneliness,” Beam said, “we eventually might be able prevent some of the long-term harm it can cause.”
About the study
In addition to Beam, researchers on the study include Morgan Lynch, Alaina Gold and Alyssa Kam of USC Dornsife; Ebrahim Zandi of the Keck School of Medicine of USC; Thalida Em Arpawong of USC Leonard Davis School of Gerontology; Kelly Bakulski of the University of Michigan, Ann Arbor; Eric Turkheimer and Sophie Bell of the University of Virginia, Charlottesville; and Jonathan Becker and Deborah Winders Davis of the University of Louisville, Louisville.
The study was supported by National Institute on Aging grant R01AG063949.