Loneliness and social isolation are widespread in the United States, with a 2023 report noting that about half of adults experience loneliness and nearly as many are socially isolated. Despite health consequences that can rival other major risk factors, the issues have long been overlooked as urgent public health concerns.
Researchers at Tulane University’s Celia Scott Weatherhead School of Public and Tropical Medicine have now attempted to quantify just how many years of good health might be lost to loneliness and social isolation. Their observational study, published in Nature Communications, found that loneliness and social isolation were associated with the loss of nearly six years of life free from mental disorders such as depression and anxiety, with physical-health effects smaller but still significant.
“Overall, the study found that social isolation and loneliness can have a significant impact on disease-free life expectancy,” said lead author Lu Qi, HCA Regents Distinguished Chair and professor in Celia Scott Weatherhead School of Public and Tropical Medicine at Tulane. “This includes both physical and mental disease.”
Researchers distinguish between loneliness and social isolation, though they are often treated as the same in everyday talk. Social isolation refers to an objective lack of social connections, whereas loneliness describes a person’s subjective dissatisfaction with the quality of their relationships, regardless of how many social interactions they actually have.
“The findings weren’t surprising to me,” Qi said. “Previous studies found that social isolation and loneliness are related to mortality, especially premature mortality, and this study provides additional evidence.”
Tracking more than 277,000 adults
The study analysed data from 277,489 adults aged between 40 and 69. At the outset, none had seven major chronic conditions—diabetes, heart disease, lung disease, dementia, cancer, depression or anxiety.
Using age 50 as a reference point, the researchers calculated how loneliness and social isolation were associated with the number of years participants could expect to live without these diseases.
Compared with people who experienced neither loneliness nor social isolation, women experiencing both had 2.4 fewer years free from physical disease, while men experienced 1.7 fewer years.
The difference was even larger for mental health. Women experiencing both loneliness and social isolation lived about 3.7 fewer years without mental disorders, while men lived approximately 5.8 fewer years free from those conditions.
“This comes down to the gender differences between men and women,” Qi said. “Our research found men are more susceptible to being affected by loneliness. We also know that women tend to live longer than men. There are gender advantages with certain diseases.”
Healthy habits help with isolation, but not loneliness
The researchers also examined whether healthier lifestyle choices could alter these associations. A healthier diet, regular exercise, sufficient sleep and not smoking reduced the loss of disease-free years linked to social isolation.
Loneliness, by contrast, produced a different pattern. A healthier lifestyle did not significantly reduce the additional health risks linked to feeling lonely, suggesting that loneliness and social isolation may require distinct approaches to health protection.
The team plans to study additional population groups in the future and to use clinical trials to investigate whether loneliness and social isolation directly cause the health effects observed in the study.
