Short-term impacts of air temperature on hospitalizations for mental disorders in Lisbon
Graphical abstract
Introduction
The effect of ambient temperature on human health is well known, with several studies providing evidence supporting the association between temperatures and several diseases (Ballester, 2003). These studies usually show an increasing trend for morbidity and mortality as the temperature deviates from the optimum temperature value (Curriero et al., 2002; Gasparrini et al., 2015). The magnitude of the morbidity and mortality increase changes significantly between diseases and regions, depending on environmental, socioeconomic and biological factors (Almendra et al., 2017; Bunker et al., 2016; Iñiguez et al., 2010).
When comparing to other diseases (e.g. cerebrovascular, cardiovascular, respiratory), the effects of temperature on mental health are not often studied (Bunker et al., 2016), probably due to the complexity of interactions between all the environmental and non-environmental determinants that may interfere with mental health and wellbeing. A common misbelief persists that mental illness is associated instead with winter weather conditions (Rau, 2004) when, in fact, the number of hospital admissions for mental diseases tends to increase with higher temperatures (Peng et al., 2017; Vida et al., 2012).
Individuals with mental illness are more vulnerable to the effects of extreme temperature due to the disruption of normal thermoregulation functions from the use of psychotropic medication, psychiatric illness, and due to behavioral issues (Hansen et al., 2008; Wang et al., 2014). Studies from Sulman (Sulman et al., 1978, Sulman et al., 1970) have suggested that the increased vulnerability associated with heat may be attributed to atmospheric electrical changes, in particular, air ion concentrations and the ion polarity ratio, which interfere with the serotonin system.
Several other environmental factors such as air pollution and pollen concentration may play an important role in the development of mental disorders. Shin et al. (2018) identified a positive association between high concentrations of air pollutants (PM10, NO2, and CO) and the prevalence of high stress, depressiveness, diagnosis of depression, and suicide ideation. Allergic symptoms due to pollen concentration was found to be associated with aggravation of anxiety symptoms (Postolache et al., 2008), with the worsening of depression In patients with bipolar disorders (Manalai et al., 2012) or suicide behavior (Besancenot et al., 2011).
In 2014, Portugal ranked second amongst the European Union countries with highest percentage of people reporting depressive symptoms (Eurostat, 2018) and third with respect to higher prevalence of chronic depression (OECD, 2017). Despite the significant extent of Mental Disorders (MD) and their social and economic consequences, the role of ambient temperature in mental health is still to be addressed. It is believed that a better understanding of the relationship between temperature and mental illness may contribute to better response care and preparedness of the medical system. Thus, this study aims to assess the short-term impacts of daily mean temperature on hospitalizations for MD in the Lisbon (Portugal) Metropolitan Area (henceforth referred to as Lisbon).
Section snippets
Location
The Lisbon Metropolitan Area is an administrative region organized into 18 municipalities distributed along the north and south shores of the Tagus River (Fig. 1). Lisbon has the largest population concentration in Portugal, and nearly 96% of the population live in predominantly urban areas. According to the Statistics Portugal (2017), 2,821,349 inhabitants lived in Lisbon in 2016, and the percentage of women was slightly higher than men, corresponding to 53% and 47%, respectively. About 23% of
Descriptive analysis
Between 2008 and 2014, 30,139 hospital admissions for MD were recorded (median of 12 hospitalizations per day), 14,200 for men and roughly 16,000 for women (Table 2). The median daily temperature was 16.8 °C, ranging between 3.9 °C and 32.7 °C. The median relative humidity was 72.1% (minimum: 15.6%; maximum: 100%). The median mean daily concentration of O3 was 70.5 μg/m3 and 20.8 μg/m3 for Pm10.
Distributed lagged effects of temperature on hospital admissions
The association between daily mean temperature and MD was estimated over a 7-day period and is
Discussion
To our knowledge, this is the first study assessing the association between ambient temperature and hospital admissions for MD in Portugal. The methods applied in this study are widely used to analyze lag-exposure-response relationship in time-series studies (Antunes et al., 2017; Gasparrini et al., 2015; Peng et al., 2017).
A significant positive association between mean daily temperature and hospital admissions by MD was found above 30 °C between on the day of exposure, and 27 °C at lag 0–1
Conclusion
The findings of this study are in conformity with similar studies applied in different locations, suggesting that high temperatures are indeed a significant risk for MD in the Lisbon Metropolitan Area. The results of this study highlight the need to strengthen patient management services following extreme high temperatures alerts and to include measures to decrease the vulnerability of individuals in healthcare programs.
Acknowledgments
This study was funded by FCT doctoral fellowship SFRH/BD/92568/2013 and by the CEGOT group Cities, competitiveness, and well-being (UID/GEO/04084/2013) through COMPETE 2020. Giovani Silva was partially funded by FCT-Portugal project UID/MAT/00006/2013.
References (36)
- et al.
Effects of air temperature on climate-sensitive mortality and morbidity outcomes in the elderly; a systematic review and meta-analysis of epidemiological evidence
EBioMedicine
(2016) - et al.
Mortality risk attributable to high and low ambient temperature: a multicountry observational study
Lancet
(2015) - et al.
Effects of ambient temperature on daily hospital admissions for mental disorders in Shanghai, China: a time-series analysis
Sci. Total Environ.
(2017) - et al.
Ambient temperature and added heat wave effects on hospitalizations in California from 1999 to 2009
Environ. Res.
(2018) - et al.
Acute impacts of extreme temperature exposure on emergency room admissions related to mental and behavior disorders in Toronto, Canada
J. Affect. Disord.
(2014) - et al.
Evidence of social deprivation on the spatial patterns of excess winter mortality
Int. J. Public Health
(2017) - et al.
The effect of extreme cold temperatures on the risk of death in the two major Portuguese cities
Int. J. Biometeorol.
(2017) - et al.
Heat wave impact on morbidity and mortality in the elderly population: a review of recent studies
Maturitas
(2011) Weather, climate, and public health
J. Epidemiol. Community Health
(2003)- et al.
Has allergenic pollen an impact on non-allergic diseases?
Eur Ann Allergy Clin Immunol
(2011)
Age-dependent changes in temperature regulation - a mini review
Gerontology
The impact of the July 2007 heat wave on daily mortality in Belgrade, Serbia
Cent. Eur. J. Public Health
Temperature and mortality in 11 cities of the eastern United States
Am. J. Epidemiol.
The impact of heat waves on mortality in 9 European cities: results from the EuroHEAT project
Environ. Health
Current depressive symptoms by sex, age and income quintile
Europe PMC Funders Group distributed lag linear and non-linear models in R: the package dlnm
J. Stat. Softw.
Modeling exposure-lag-response associations with distributed lag non-linear models
Stat. Med.
Time series analysis on the health effects of temperature: advancements and limitations
Environ. Res.
Cited by (47)
Seasonality in U.S. disability applications, labor market, and the pandemic echoes
2024, Labour EconomicsDescriptive analysis of occupational accidents in Spain and their relationship with heatwaves
2023, Preventive MedicineClimatic and meteorological exposure and mental and behavioral health: A systematic review and meta-analysis
2023, Science of the Total EnvironmentShort-term effect of apparent temperature on daily hospitalizations for osteoporotic fractures in Beijing, China: A retrospective observational study
2023, Science of the Total Environment