Background: Depression is one of the most prevalent mental disorders globally and has implications for various aspects of everyday-life. To date, studies assessing the association between social relationships and depression have provided conflicting results. The aim of this paper was to review the evidence on associations between social relationships and depression in the general population.

Methods: Studies investigating the association of social support, social networks, or social connectedness with depression were retrieved and summarized (searches using Pubmed, ScienceDirect, PsycNet were conducted in May 2014).

Results: Fifty-one studies were included in this review. The strongest and most consistent findings were significant protective effects of perceived emotional support, perceived instrumental support, and large, diverse social networks. Little evidence was found on whether social connectedness is related to depression, as was also the case for negative interactions.

Limitations: Due to the strict inclusion criteria relating to study quality and the availability of papers in the domain of interest, the review did not capture 'gray literature' and qualitative studies.

Conclusion: Future research is warranted to account for potential bias introduced by the use of subjective measures as compared to objective measures of received support and actual networks. Due to the heterogeneity between available studies on the measure of social relationships, the inclusion of comparable measures across studies would allow for more valid comparisons. In addition, well-designed prospective studies will provide more insight into causality. Future research should address how social support and networks interact and together affect risks for depression. Social connectedness and negative interactions appear to be underutilized as measures in population-based studies.