Until recently, researchers had limited evidence about how many years of healthy life could be lost because of loneliness and social isolation.

Loneliness and isolation linked to a shorter healthy lifespan

Researchers at Tulane University’s Celia Scott Weatherhead School of Public Health and Tropical Medicine are now working to quantify the potential health impact. Their first observational study, published in Nature Communications, found that loneliness and social isolation were associated with losing nearly six years of life free from mental illnesses such as depression and anxiety. The impact on physical health was smaller but still significant.

“Overall, this 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 at Tulane’s Celia Scott Weatherhead School of Public Health and Tropical Medicine. “This includes both physical and mental illnesses.”

Loneliness and social isolation are often treated as the same thing in everyday conversation, but researchers distinguish between them. Social isolation refers to an objective lack of social connections. Loneliness, by contrast, is an individual’s subjective dissatisfaction with the quality of their relationships, regardless of how many social interactions they have.

“This finding was not surprising to me,” Qi said. “Previous studies have found that social isolation and loneliness are associated with mortality, particularly premature mortality, and this study provides further evidence.”

Study tracked more than 277,000 adults

Researchers analyzed data from 277,489 adults between the ages of 40 and 69. At the beginning of the study, none of the participants 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 related to the number of years participants could expect to live without these illnesses.

Compared with people who experienced neither loneliness nor social isolation, women who experienced both were expected to have 2.4 fewer years free from physical illness. For men, the difference was 1.7 years.

The gap was even greater for mental health. Women who experienced both loneliness and social isolation lived approximately 3.7 fewer years free from mental illness, while men lived approximately 5.8 fewer years free from mental illness.

“This is due to gender differences between men and women,” Chee said. “Our study found that men are more susceptible to the effects of loneliness. We also found that women tend to live longer than men. Certain diseases have gender advantages.”

Healthy habits may help with social isolation, but not loneliness

The researchers also examined whether lifestyle factors could alter these associations. Healthy habits—including eating a nutritious diet, exercising regularly, getting enough sleep and not smoking—measurably reduced the loss of disease-free years associated with social isolation.

Loneliness showed a different pattern. A healthier lifestyle did not significantly reduce the additional health risks associated with loneliness. This difference suggests that loneliness and social isolation may require separate approaches to protect health.

The researchers plan to study larger populations and use clinical trials to investigate whether loneliness and social isolation directly cause the health effects observed in the study.