"What this study shows is that the biological impact of social isolation reaches down into some of our most basic internal processes — the activity of our genes," says Steve Cole, an associate professor of medicine in the division of hematology and oncology at the David Geffen School of Medicine at UCLA and a member of the Cousins Center for Psychoneuroimmunology, in an article published in the UCLA Newsroom.

"We found that changes in immune cell gene expression were specifically linked to the subjective experience of social distance," says Cole in the article. "The differences we observed were independent of other known risk factors, such as health status, age, weight and medication use. The changes were even independent of the objective size of a person's social network."

Social isolation can also increase the risk of death. In fact, a study conducted by Brigham Young University and published in Perspectives on Psychological Science concluded that loneliness can increase the risk of death by 26 percent.

Those involved in the project find this statistic to be extremely concerning. “This is something that we need to take seriously for our health,” Brigham Young University researcher Julianne Holt-Lunstad, an author of the study, told Time. “This should become a public-health issue.” 

Other research suggests that loneliness can increase the risk of Alzheimer’s disease. In fact, one study found that the risk of Alzheimer’s disease was more than twice as high in people who are lonely compared to those who aren’t. In addition, those who feel lonely may experience faster cognitive decline in relation to the disease than those who are not lonely.