Prevalence of common mental disorders in survivors of natural hazards – a meta-analytic comparison of exposed vs. non-exposed samples

Previous studies have reported high prevalence of common mental disorders in populations affected by natural hazards. Yet, it remains largely unknown to what extent the prevalence exceeds that of populations with similar backgrounds that have not been exposed to natural hazards. We conducted a meta-analysis comparing prevalence and symptom severity of mental disorders in survivors of natural hazards compared to non-exposed controls. We identified 41 reports of 33 studies with 30,508 participants and conducted random-effects meta-analyses. Being hazard-exposed (vs. non-exposed) was associated with significantly increased odds for current posttraumatic stress disorder (PTSD) in the first year after the event (OR = 4.46, 95 % CI 2.15; 9.26; n = 8,808) and in the long-term (mean: 12 years post-hazard, OR = 1.84, 95 % CI 1.32; 2.57; n = 2,199). There was an increased likelihood of current depression diagnosis on average four years following a hazard (OR, 3.38, 95 % CI 2.18; 5.26; n = 5,207). Three-level models showed significantly higher symptom severity of PTSD and depression in the hazard-exposed compared to the non-exposed group with moderate-to-large effects. Findings on other mental disorders were constrained by the limited number of available studies. Our results suggest that being exposed to natural hazards is associated with a considerable increased long-term risk of PTSD and depression relative to non-exposure. The findings highlight the need for both effective prevention and treatment as part of climate change mitigation strategies.