Unmarried people may be about 80% more likely to have depressive symptoms than those who are married, suggests an analysis of more than 100,000 individuals across 7 countries, published in Nature Human Behaviour.

The risk of depression for unmarried individuals was also found to be higher in male individuals and those who had higher educational attainment. The findings may help identify demographic groups at higher risk of depression.

Depression is a major public health issue, and approximately 5% of adults worldwide have major depressive disorder. Although previous research has suggested that marriage may lower the risk of depression, these studies often focus on single (often Western) countries.

Additionally, results across these studies have often differed by country, and little is known about the interplay between marital status and other factors, including variations in socioeconomic status, age and education.

Kefeng Li and colleagues analyzed individual-level data from 106,556 participants in 7 countries—US, UK, Mexico, Ireland, South Korea, China, and Indonesia—to investigate the risk of depressive symptoms among married and unmarried individuals across a follow-up period of 4 to 18 years for a subset of 20,865 individuals. They found that unmarried status is associated with a 79% higher risk of depressive symptoms compared to those who are married.

Divorced or separated individuals had a 99% higher risk of depressive symptoms, and widowed individuals had a 64% higher risk than married individuals. Unmarried participants in Western countries (including the US, UK and Ireland) had a higher risk of depression than their counterparts in Eastern countries (including South Korea, China and Indonesia). This risk was found to be greater among unmarried male individuals as compared to unmarried female individuals, and in those with higher versus lower educational attainment.

Li and colleagues suggest that the lower rates of depression among married couples could be due to the exchange of social support within a couple, better access to economic resources and positive influence on each other's well-being. However, the authors note that a limitation of the study is that data were collected via self-report questionnaires and not from clinical diagnoses of depression, and that all of the couples analyzed in this study were heterosexual.