Unmarried individuals 80% more likely to experience depressive symptoms compared to married counterparts

 Researchers suggest that the lower rates of depression among married couples could be attributed to the exchange of social support, better access to economic resources, and a positive influence on each other’s well-being.

In a recent study published in Nature Human Behaviour, a group of researchers investigated the association between marital status and depressive symptoms across seven culturally diverse countries while examining the mediating effects of education level, sex, and substance use on this relationship.

Background 

Depression is a significant global public health challenge, with an estimated prevalence of 5% among adults, projected to exceed 10% by 2025 in the post-pandemic era. It is linked to various somatic conditions, disability, and suicide, highlighting the need to identify modifiable risk factors.

While marital status is associated with mental health, most research has focused on Western countries, suggesting that marriage may protect against depression. However, socio-economic, cultural, and educational differences may affect these associations globally.

Further research is needed to explore the moderating factors and causal mechanisms influencing the relationship between marital status and depressive symptoms.

About the study

The present study utilized de-identified, nationally representative individual-level data from seven culturally diverse countries, including the United States of America (USA), United Kingdom (UK), Mexico, Korea, Ireland, China, and Indonesia, to explore the relationship between marital status and depressive symptoms.

In the first stage, a cross-sectional analysis was performed using population-based data from various surveys, with a total of 106,556 participants included after excluding those with missing data. The second stage involved a prospective longitudinal analysis, focusing on causal mechanisms, which included 20,865 participants after excluding those with incomplete baseline data or pre-existing depressive symptoms.

Marital status was categorized into four groups based on self-reported status: married, divorced/separated, single, and widowed. Mediators such as alcohol consumption and smoking were assessed through self-administered questionnaires. Depressive symptoms were evaluated using standardized instruments, ensuring comparability across countries. Key covariates included age, sex, income, educational attainment, and body mass index (BMI).

Statistical analyses involved survey-weighted logistic regression and multivariate causal mediation analysis to determine associations and underlying mechanisms, employing methodologies like bootstrapping for validation. All analyses were conducted using SAS, R, or GraphPad Prism, with a significance threshold set at p < 0.05, highlighting the study’s rigorous approach to examining complex relationships between marital status and mental health. 

Study results

The present study utilized a two-stage design integrating cross-sectional and longitudinal analyses, involving a total of 106,556 participants from eight cohorts across seven countries. Among these, 49,547 were male, with 22,490 individuals exhibiting depressive symptoms. The proportion of participants reporting marital status varied significantly by cohort, with 64.3% in the National Health and Nutrition Examination Survey (NHANES) cohort (USA) and 87.6% in the China Health and Retirement Longitudinal Study (CHARLS) cohort (China). Notably, educational attainment also differed across countries.

The longitudinal stage of the study included 20,865 participants, with a mean follow-up duration ranging from four years in the Korean Longitudinal Study of Aging (KLoSA) cohort to 18 years in the Wisconsin Longitudinal Study (WLS) cohort. During this period, 4,486 participants developed depressive symptoms.

The multivariable-adjusted analysis revealed that unmarried individuals had a significantly higher risk of depressive symptoms compared to their married counterparts, with a pooled odds ratio (OR) of 1.86 across all cohorts. The analysis further explored subcategories of unmarried status, showing increased risks of depressive symptoms for singles (OR: 1.79), divorced/separated individuals (OR: 1.99), and widowed participants (OR: 1.64). These associations remained consistent across sensitivity analyses.

The study identified several moderators affecting the relationship between marital status and depressive symptoms, including sex, country, and educational attainment. Unmarried individuals in Western countries exhibited a greater risk of depressive symptoms compared to those in Eastern countries. Furthermore, males demonstrated a higher risk of depressive symptoms associated with marital status than females, particularly among single individuals. The relationship between marital status and depressive symptoms was most pronounced in participants with higher educational attainment.

In examining causal mediators, the analysis highlighted alcohol consumption and smoking as significant pathways linking marital status to depressive symptoms. For instance, alcohol consumption mediated a notable portion of the risk among divorced/separated individuals in Korea, Mexico, and China. Similarly, smoking was identified as a significant causal pathway among single individuals from Mexico and China. However, no significant mediating effects were observed among unmarried Americans or Irish. 

Conclusions

To summarize, findings revealed that unmarried individuals had a higher risk of depressive symptoms compared to married counterparts, with variations based on sex, country, and educational attainment.

Notably, alcohol consumption and smoking served as significant mediators for increased depressive symptoms among unmarried individuals in China, Korea, and Mexico. The study emphasized the influence of cultural and societal factors on mental health and the importance of addressing these issues.