The impact of climate change on mental health in vulnerable groups: a systematic review

Background: Climate change events may disproportionately affect vulnerable groups, exacerbating existing socioeconomic, racial, and cultural inequalities. This systematic review summarises the evidence on the mental health impacts of climate change events on vulnerable populations: (1) low socioeconomic status groups; (2) minoritised ethnic or racial groups; (3) Indigenous groups; and (4) housing-insecure groups. Methods: We searched MEDLINE, EMBASE, PsycINFO, Scopus, Web of Science for studies published before 17 July 2023 (PROSPERO: CRD42023442489). Key search terms included (1) climate change events; (2) mental health; and (3) vulnerable groups. Titles/abstracts and full texts were screened for inclusion, followed by quality assessment and narrative synthesis. Results: Of the 1,197 articles were retrieved, and 32 met inclusion criteria. Most studies (n=27) examined acute weather events, with few exploring sub-acute weather events (n=2), gradual environmental changes (n=2), or combined events (n=2). Studies predominantly examined low socioeconomic groups (n=26) and minoritised ethnic or racial groups (n=12), with limited research on Indigenous groups (n=2) or housing-insecure groups (n=1). The most common mental health outcomes were post-traumatic symptoms/disorder (n=15), depressive disorder (n=12), general mental health (n=8), anxiety disorder (n=6), and psychological distress (n=6). 25 of the studies originated from high-income countries, 8 were from middle-income countries, and none from low-income countries. Study quality varied: 7 rated low, 16 medium, and 9 high. Eighteen studies found worse mental health outcomes in vulnerable groups following climate change exposure compared to the general population, five studies found mixed results, and nine found no evidence of worse outcomes in vulnerable groups. Conclusions: Vulnerable groups generally experienced worse mental health outcomes following climate change events compared to the general population, though some studies found mixed or null effects. There were critical evidence gaps, including limited high-quality evidence on sub-acute and gradual climate change events, Indigenous or housing-insecure groups, and low-and-middle-income countries. The wide range of mental health outcomes assessed makes direct comparisons challenging. Addressing these gaps is critical to understanding the interplay between existing social inequalities and the mental health impact of climate change, as well as informing effective public health policies in the context of increasing frequency and severity of climate change events globally.