Divorced people are three times more likely to be depressed than people who are married, a study has found.

Questionnaires sent to more than 100,000 people in seven countries revealed that, overall, unmarried people are 79 per cent more likely to report depressive-like symptoms than those in a marriage.

In the UK, unmarried people are 2.3 times more likely to be depressed.

About 2 per cent of the married British people in the study said they were depressed, but this rose to 6.6 per cent for those who are divorced and 4 per cent for widows.

This is a 2.9 and 2.3-fold increased risk of depression compared with those who are married, respectively, when accounting for a range of other factors, such as health, age, sex and income.

Previous studies have found marriage reduces depression risk, but this study is the first to focus on the impact of matrimony internationally.

It found that while married people worldwide were less likely to be depressed, the effect was significantly more noticeable in Western countries such as the UK and Ireland.

In Indonesia, for example, unmarried people are 28 per cent more likely to be depressed than those who are married, while in Korea it is 47 per cent and in China 52 per cent.

In contrast, unmarried people are more than twice as likely to be depressed than married peers in both the United States and Ireland, as well as the UK.

"This finding implies that cultural, societal and economic factors unique to certain countries may influence the relationship between marital status and depressive symptoms," the scientists from Harvard and Macao Polytechnic University write in their study.

"Eastern cultures tend to tolerate higher levels of emotional distress before it becomes problematic, which may partially explain the lower risk of depressive symptoms in unmarried participants from these countries."

The study also found that unmarried men were more likely to be depressed than unmarried women. In the UK, an unmarried man was 2.93 times more likely to be depressed than a married one, while an unmarried woman was 2.6 times more likely to be depressed than a married one.

The study's authors attribute this higher risk in men to women having "larger and stronger social support networks".

"[This study] found that being unmarried, regardless of subcategories, was associated with a higher risk of having depressive symptoms," the authors write in their study, published in the journal Nature Human Behaviour.

"This heightened vulnerability emerged especially among single, highly educated males in Western nations."