People who are unmarried may be around 80% more likely to be experiencing depression than those who are married, new research suggests.
The study found the risk of depression for unmarried people could be higher in men and those who had more education.
Scientists suggest the findings may help with the identification of people who are at higher risk of the condition.
The authors suggest the lower rates of depression among married people could be because couples are able to socially support one another, have better access to economic resources and have a positive influence on each other’s well-being.
They analysed data from more than 100,000 people across seven countries, including nearly 7,000 from the UK.
Some 222 people from the UK’s 2007 Adult Psychiatric Morbidity Survey (APMS) reported having symptoms of depression.
Of those, 73 were married, 62 were single, 55 were divorced or separated and 32 were widowed.
“Our cross-country analysis suggests that unmarried individuals may be at greater risk of depression, and any efforts to mitigate this risk should consider the roles of cultural context, sex, educational attainment and substance use,” Kefeng Li of Macao Polytechnic University in Macau, China, and colleagues wrote in the journal Nature Human Behaviour.
Divorced or separated people had 99% higher risk of depression
The study, which also looked at people in the US, Mexico, Ireland, South Korea, China, and Indonesia over a follow-up period of four to 18 years, found being unmarried was associated with a 79% higher risk of depressive symptoms compared to those who are married.
It also found people who were divorced or separated had a 99% higher risk of showing signs of depression.
Meanwhile, those who were widowed had a 64% higher risk than those who were married.
Unmarried people in Western countries had a higher risk of depression than those in Eastern countries, according to the study.
Around 280 million people across the world have depression, accounting for about 5% of the world’s adult population, according to the World Health Organisation (WHO).
The authors noted the data was collected from self-reported questionnaires and not from clinical diagnoses of depression.
They also said all of the couples analysed were heterosexual.