Chronic and transient loneliness in Western countries: risk factors and association with depression. A two-year follow-up study.

Depression is one of the most prevalent mental disorders and one that contributes substantially to the global burden of disease. The prevalence of the global population with depression in 2015 was 4.4% [1]. Among the main predictors of depressive disorders and symptoms in the elderly, lack or loss of close social contacts and, particularly, feelings of loneliness have a stronger association with depression than do other modifiable risk factors [2–4]. While the relationship between loneliness and depression might be bidirectional, prior research indicates that the prospective association between loneliness and depression is clearly stronger with loneliness as the origin [4,5].