How Much Depression Shortens Life, Measured Across Millions

This is the most comprehensive quantification to date of how depression relates to length of life, and its scale is what gives it weight. Researchers pooled 268 cohort studies covering more than ten million people with diagnosed depression against a control population numbering in the billions. The headline figure is stark: all-cause mortality was about twice as high in people with depression, a relative risk of 2.10. The excess was greatest for suicide, but was also clearly raised for deaths from natural causes, meaning the effect is not explained by suicide alone but runs through the body. Two findings matter for how the number should be read. First, when people with depression were compared with others carrying the same physical illnesses, the raised risk shrank but did not vanish, so comorbidity explains part of the association but not all of it. Second, the analysis examined treatment as a moderator rather than assuming depression is fixed. Where the evidence stops: these are observational studies with very high statistical heterogeneity, so the precise magnitude varies by population, and association is not proof that depression itself causes each death. What is beyond reasonable doubt is the direction and seriousness. Depression is not only a burden on quality of life but a measurable risk to its length, which is the strongest possible argument for treating it as central to whole-body health rather than separate from it.