The effect of average temperature on suicide rates in five urban California counties, 1999–⁠2019: an ecological time series analysis

Abstract

Background Suicide is among the top 10 leading causes of premature morality in the United States and its rates continue to increase. Thus, its prevention has become a salient public health responsibility. Risk factors of suicide transcend the individual and societal level as risk can increase based on climatic variables. The purpose of the present study is to evaluate the association between average temperature and suicide rates in the five most populous counties in California using mortality data from 1999 to 2019. Methods Monthly counts of death by suicide for the five counties of interest were obtained from CDC WONDER. Monthly average, maximum, and minimum temperature were obtained from nCLIMDIV for the same time period. We modelled the association of each temperature variable with suicide rate using negative binomial generalized additive models accounting for the county-specific annual trend and monthly seasonality. Results There were over 38,000 deaths by suicide in California’s five most populous counties between 1999 and 2019. An increase in average temperature of 1 °C corresponded to a 0.82% increase in suicide rate (IRR = 1.0082 per °C; 95% CI = 1.0025–1.0140). Estimated coefficients for maximum temperature (IRR = 1.0069 per °C; 95% CI = 1.0021–1.0117) and minimum temperature (IRR = 1.0088 per °C; 95% CI = 1.0023–1.0153) were similar. Conclusion This study adds to a growing body of evidence supporting a causal effect of elevated temperature on suicide. Further investigation into environmental causes of suicide, as well as the biological and societal contexts mediating these relationships, is critical for the development and implementation of new public health interventions to reduce the incidence of suicide, particularly in the face increasing temperatures due to climate change.

Assessing the Burden of Suicide Death Associated With Nonoptimum Temperature in a Changing Climate

“…Our results suggest that higher temperature was associated with an increased risk of suicide death with an approximately linear relationship, which is consistent with previous studies . For example, a multicountry analysis indicated that higher ambient temperature was associated with increased risks of suicide death, with the country-specific RRs ranging from 1.31 in the US to 1.61 in South Korea, which is comparable to our estimate (RR = 1.44).…”

“…mately linear relationship, which is consistent with previous studies. 13,17,18,22 For example, a multicountry analysis indi-cated that higher ambient temperature was associated with increased risks of suicide death, with the country-specific RRs The associations were presented as the cumulative relative risks comparing a given temperature with the minimum-mortality temperature over a 0-to 3-day lag. The solid lines are mean risk estimates, and the shaded areas are their 95% CIs.…”

The Impact of Foehn Wind on Mental Distress among Patients in a Swiss Psychiatric Hospital

“…Extreme weather events elevate the risk of symptom exacerbation (cf. Lõhmus [ 58 ]), suicide [ 8 , 13 , 14 , 15 ], and a three-times-higher risk of mortality during heatwaves compared to people without mental disorders [ 18 ]. Other marginalized groups constitute women (especially pregnant or postnatal women), children, groups with less social support, insufficient medical care, people suffering from financial difficulties, and minoritized ethnic groups [ 3 , 23 , 65 , 66 , 67 , 68 , 69 , 70 ].…”

“…Data particularly show negative consequences related to ambient temperature and heat, with an increase in temperature being associated with an increase in mental distress, hospitalizations for mental disorders (including bipolar disorder, schizophrenia, and dementia) [ 8 , 10 , 11 , 12 ], and increased suicide rates [ 6 , 8 , 13 , 14 , 15 , 16 ].…”

The Impact of Foehn Wind on Mental Distress among Patients in a Swiss Psychiatric Hospital

“…Extreme weather events elevate the risk of symptom exacerbation (cf. Lõhmus [57]), suicide [8,[13][14][15], and a three times higher risk of mortality during heatwaves compared to people without mental disorders [18]. Other marginalized groups constitute women (especially pregnant or postnatal women), children, groups with less social support, insufficient medical care, people suffering from financial difficulties, and minoritized ethnic groups [3,23,[64][65][66][67][68][69].…”