The deadliness of loneliness

In May 2023, US Surgeon General Vivek Murthy, MD, MBA, issued a stark health advisory. “Our epidemic of loneliness and isolation has been an underappreciated public health crisis that has harmed individual and societal health,” he asserted. Dr Murthy cited research suggesting that poor social connections increase the risk of depression, anxiety, heart disease, stroke, dementia in older adults, and premature death. The World Health Organization likewise declared loneliness a global health threat in 2023, and other countries have raised the alarm on a problem likely exacerbated by social distancing during the coronavirus disease 2019 pandemic.

Studies of people who are lonely, socially isolated, or living alone have expanded the potential consequences to include a higher risk of developing and dying of cancer, increasing the urgency of understanding the problem, its contributing factors, and the potential solutions.

Despite the flurry of attention, Frank Infurna, PhD, a professor of psychology at Arizona State University in Tempe, says that the loneliness “epidemic” has been more of an endemic but growing problem in the United States, particularly within the Baby Boomer and Gen X generations. “We’re seeing over multiple generations, over multiple cohorts, that loneliness levels within the US are elevated. So, it’s been a problem not just recently; it’s been a problem for a while,” he says.

Kerri Winters-Stone, PhD, an exercise scientist and professor in the Division of Oncological Sciences at the Oregon Health & Science University in Portland, began shifting her work to focus on loneliness among cancer survivors a few years ago. “I think it’s a bigger problem than we’re acknowledging,” she says. If loneliness and isolation should be treated as cancer-abetting threats akin to smoking and the human papillomavirus, however, studies have not yet settled on how to similarly tamp down the danger.

The problem is complicated by related but different kinds of “aloneness.” Social isolation, for example, refers to a small or nonexistent social network or a lack of meaningful engagement with others, whereas loneliness refers to a mismatch between desired and actual social connections—the unwanted feeling of being alone or not close to others. “A person can be socially isolated but may not feel lonely, and vice versa,” says Hyunjung Lee, PhD, MS, MPP, MBA, a principal scientist on the American Cancer Society’s Cancer Disparities Research Team (the American Cancer Society publishes Cancer Cytopathology).

Living alone, by contrast, is a more objective measure “that can be easily assessed with a single question on the number of people in the household,” Dr Lee says. “People who live alone are more likely to be socially isolated or feel lonely, although this is not always the case.” Research also suggests that older people are more likely to live alone in the United States than elsewhere around the world—in agreement with studies suggesting that they also are more likely to be isolated and lonely.¹

A 2023 study led by Dr Lee found that working-age US adults who live alone, and thus are more likely to be isolated, have a higher risk of cancer-associated death than adults who live with others.² “Individuals who are socially isolated are more likely to smoke but less likely to maintain healthy diet, sleep, and physical activity or seek and adhere to medical care when needed,” she says. “Social isolation is also associated with stress, depression, and loneliness, which involves the hypothalamic-pituitary-adrenal axis and autonomic nervous system, leading to angiogenesis and promotion of tumor growth, which can result in accelerated cancer progression and death.”

The association between living alone and increased cancer mortality was most significant in non-Hispanic White adults, less significant in non-Hispanic Black adults, and absent in Hispanic, American Indian or Alaska Native, and Asian adults. Dr Lee suggests that some of the differences may be due in part to the level of social support from an individual’s broader community. Stronger support could alleviate some negative aspects of living alone, although she emphasizes that more research is needed on the contributing factors.

A separate 2023 meta-analysis of 90 studies from mostly higher income countries found that “both social isolation and loneliness were significantly associated with an increased risk of all-cause mortality and cancer mortality.”³ The study added to the growing evidence that the problem is worse in the United States: It found a significantly greater association between social isolation and all-cause mortality in Americans than in their foreign counterparts.

Even worse, other evidence suggests that both loneliness and isolation are increasing in the United States. In a study of 45- to 65-year-old people from the United States and 13 European countries, Dr Infurna and his colleagues found that Baby Boomers had the highest overall levels of loneliness, and that American Baby Boomers far outpaced their international peers.⁴ “It was certainly a surprise,” he says. “It really made us stop and pause for a bit.” In fact, the study found that the overall levels of loneliness in the United States were consistently higher than those in all other countries surveyed.

What might help to reverse the growing problem? For patients who live alone, Dr Lee says, patient navigation programs may help to increase the uptake of, and adherence to, cancer screening. That assistance, in turn, could aid the “timely diagnosis, treatment, and attendance of medical appointments, especially among historically marginalized populations,” she says. More generally, Dr Infurna suggests that finding ways to be more engaged in the community, such as volunteering or joining a church, club, or gym, may help to foster more meaningful interactions, friendships, and mutual support.

Dr Winters-Stone, in fact, has gathered some initial data pointing to the potential benefits of group exercise. She and her colleagues enrolled several hundred men with prostate cancer in a trial initially designed to assess the impact of an instructor-led group exercise program on reducing falls associated with hormone therapy. From listening to the participants’ conversations, however, she realized that the group exercise also might reduce feelings of loneliness, and she began tracking that metric as well in 145 of the men.

Approximately 87% of the men in that group were married. Even so, roughly 70% reported experiencing some level of isolation and disconnection due to what she terms cancer-related loneliness: “You don’t have people that you can talk to and confide in about your cancer diagnosis.” The program, now conducted virtually over Zoom, has included opportunities for the men to interact socially through breakout rooms. Initial findings, which Dr Winters-Stone presented in November at the annual Gerontological Society of America meeting in Seattle, suggested that the participants’ levels of cancer-related loneliness declined over a 6-month period, with the biggest declines occurring in those who initially reported the highest levels of loneliness.⁵

For men, she notes, notions of masculinity and cancer-associated stigma may prevent those who need help from asking for it. Some cancer coping mechanisms can appear as anger, and some medications can cause irritability; both can further isolate someone. “The lightbulbs, for me, just keep going off about why we need other types of social support,” Dr Winters-Stone says. Although a traditional support group may not be as desirable to some patients, an exercise or other affinity group could still provide opportunities for helpful connections. At the very least, she and other experts say, normalizing conversations about loneliness and isolation is an essential step toward more lasting—and lifesaving—solutions.