BACKGROUND: Numerous studies describe the occurrence of post-traumatic stress disorder following disasters, but less is known about the risk of major depression.

AIMS: To review the risk of depressive disorder in people surviving disasters and in soldiers returning from military deployment.

METHOD: A systematic literature search combined with reference screening identified 23 controlled epidemiological studies. We used random effects models to compute pooled odds ratios (ORs).

RESULTS: The average OR was significantly elevated following all types of exposures: natural disaster OR = 2.28 (95% CI 1.30-3.98), technological disaster OR = 1.44 (95% CI 1.21-1.70), terrorist acts OR = 1.80 (95% CI 1.38-2.34) and military combat OR = 1.60 (95% CI 1.09-2.35). In a subset of ten high-quality studies OR was 1.41 (95% CI 1.06-1.87).

CONCLUSIONS: Disasters and combat experience substantially increase the risk of depression. Whether psychological trauma per se or bereavement is on the causal path is unresolved.