Loneliness may steal nearly 6 years of good health

Researchers at Tulane University's Celia Scott Weatherhead School of Public and Tropical Medicine have put a number on the toll of loneliness and social isolation: nearly six years of life free from mental disorders such as depression and anxiety.

The observational study, published in Nature Communications, is the first of its kind to estimate how these conditions shorten disease-free life expectancy. The effects on physical health were 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 at the Tulane school. "This includes both physical and mental disease."

Although people often use loneliness and social isolation interchangeably, researchers distinguish them. Social isolation means an objective lack of social connections. Loneliness describes a person's subjective dissatisfaction with the quality of their relationships, no matter how many social interactions they 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 team analyzed data from 277,489 adults ages 40 to 69. At the start, none had seven major chronic conditions: diabetes, heart disease, lung disease, dementia, cancer, depression and anxiety.

Using age 50 as a reference, they 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, women experiencing both had 2.4 fewer years free from physical disease. Men in the same situation had 1.7 fewer years.

The gap was larger for mental health. Women who experienced both lived about 3.7 fewer years without mental disorders. 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 looked at whether lifestyle could change these associations. Healthier habits, including a better diet, regular exercise, sufficient sleep, and not smoking, measurably reduced the loss of disease-free years linked to social isolation.

Loneliness showed a different pattern. A healthier lifestyle did not significantly reduce the extra health risks tied to feeling lonely. That distinction suggests loneliness and social isolation may need different public health approaches.

The team plans to study more population groups and run clinical trials to test whether loneliness and social isolation directly cause the health effects seen here.

One important note: this is an observational study, published in a peer-reviewed journal. It shows an association, not proof of cause and effect. The researchers themselves say experimental trials are still needed.

• loneliness
• Lu Qi
• Nature Communications
• public health
• social isolation
• Tulane University