Messing with Your Head: Hurricanes, Flooding, and Heatwaves Increase the Risk of Some Mental Disorders
—Natural disasters have a complex impact on communities. These investigators found that higher risks of PTSD, anxiety, and depression were observed related to regionally relevant hazards.
Specific hazard types, including heatwaves, coastal flooding, and hurricanes, were associated with anxiety, depression, and post-traumatic stress disorder (PTSD) whereas there was no association between the overall natural hazard risk and poor mental health outcomes, a recent study suggests.1
“We aimed to evaluate the association between residential natural hazard risk and depression, anxiety, and PTSD using a hazards risk metric, the National Risk Index (NRI), accounting for community vulnerability and resilience. In addition, we evaluated adverse mental health outcomes related to specific hazard-types pertinent to communities living along the US Gulf Coast,” first author Kaitlyn G. Lawrence, PhD, Epidemiology Branch, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina, and colleagues noted in American Journal of Epidemiology.
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Study design and participants
This prospective cohort study included 32,608 adults aged 21 years or older (average age, 44; 78% men; 54% White) who had oil spill response and cleanup (OSRC) safety training but were not hired or participated in OSRC work following the Deepwater Horizon disaster. The sample included 9312 participants who completed home visit interviews and questionnaires for PTSD symptoms, generalized anxiety disorder, and major depressive disorder, and who had geocodable residential addresses and complete covariate information.
Overall, participants lived in areas with slightly increased social vulnerability index scores (53% vs 50%) and overall risk scores (55% vs 50%) compared with national US percentiles. Compared with the US national average, community resiliency scores were higher among the participants (64% vs 50%). This sample included 2327 census tracts that had 1 to 77 participants; 1212 tracts had only one participant; and 90% of tracts had 10 or fewer participants.
Associations between risk indices and mental health
There were no clear associations observed between the overall NRI and PTSD, depression, or anxiety despite a suggestive inverse association for Q3 vs Q1 between the NRI and anxiety (prevalence ratio 0.87; 95% CI 0.79–0.97).
Hurricane risk was associated with anxiety, depression, and PTSD, with increasing risk quartiles having an association with a higher depression prevalence. The strongest associations were observed between hurricane risk and PTSD (Q2 prevalence ratio 1.62 [95% CI 1.21–2.17]; Q4 prevalence ratio 2.29 [95% CI 1.74–3.01]). Associations between heatwave risk and anxiety were stronger in Q2 and Q4 but not in Q3, with similar associations observed with depression. There was a suggestive association observed between heatwave risk and PTSD in Q4 vs Q1 (prevalence ratio 1.20; 95% CI 0.94 – 1.52).
Higher risk of coastal flooding was associated with PTSD, depression, and anxiety, with the strongest associations observed for Q4 vs Q1 (prevalence ratios of 1.59, 1.19, and 1.22, respectively).
“Results stratified by participant self-reported race showed that associations were similar among Black vs. White participants with a few exceptions,” the authors noted in American Journal of Epidemiology. “Income-stratified results showed that associations were mostly similar among those making <$20,000 per year and those ≥$20,000 per year.”
Conclusions
In this study, the authors demonstrated that, despite a lack of association between the overall NRI score and mental health outcomes, there were associations between coastal flooding and hurricane risk and increased risk of PTSD, depression, and anxiety in an exposure-response manner.
“Associations between hurricane risk and mental health outcomes were suggestively stronger among White participants whereas associations with coastal flood risk were suggestively higher among Black participants,” the authors noted in American Journal of Epidemiology. “These differences may reflect different residential patterns and exposure vulnerability to specific hazards and/or underlying differences in adverse mental health burdens.”
Limitations of this study include potential underreporting or undercounting of less economically impactful hazards that contribute to mental strain, and the potential for not accounting for all direct and indirect losses due to the federal reporting data used at the census tract level.
“In this descriptive study, we observed that while overall residential natural hazard risk was not associated with adverse mental health outcomes, specific hazard types including those from hurricanes, coastal flooding, and heatwaves were associated with such outcomes, including anxiety, depression, and PTSD,” the authors concluded. “Policies targeting public mental health following natural hazards may target specific regions known to be at higher risk of hazards and consider a range of mental health conditions,” they added.
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