Unmarried people are 86% more likely to have depressive symptoms compared to married people in all countries surveyed (United States, Mexico, China, Ireland, Korea, England). Within the three categories of ‘unmarried’ (single, divorced/separated, and widowed), no significant differences are found in the risk of manifesting such symptoms. The researchers reached this conclusion after conducting a double study: a cross-sectional study and a longitudinal one with a large representative sample of people from different locations who were followed over at least 4 years (and up to 18 in the best case).

Until now, there have been no studies with such a large sample (more than 100,000 people in the first study and more than 20,000 in the second, representing around 540 million and 210 million adults) that combine different methodologies, with the longitudinal one standing out, which is the one that allows the directionality of the variables to be identified with the greatest scientific confidence. Taking all of the above into account, it seems possible to extrapolate the results to the Spanish population. As a novelty, the authors find that alcohol and tobacco consumption mediate the relationship between marital status and depression, causally increasing the subsequent risk of presenting depressive symptoms in widowed, divorced/separated and single people in China and Mexico.

As a major limitation, it should be noted that same-sex couples were not considered due to the unavailability of data on same-sex marriage, thus highlighting the need to examine health implications in this population in the future.

If unmarried people are at higher risk of depression, and arrive at it through certain cultural, socioeconomic and behavioural determinants identified in this study, these should be considered in future research to better understand and address differences in mental health associated with marital status.