A positive relationship between ambient temperature and bipolar disorder identified using a national cohort of psychiatric inpatients

Daily temperature variability and mental health-related hospital visits in New York State

BACKGROUND

Despite plausible behavioral and physiological pathways, limited evidence exists on how daily temperature variability is associated with acute mental health-related episodes.

OBJECTIVES

We aimed to explore associations between daily temperature range (DTR) and mental health-related hospital visits using data of all hospital records in New York State during 1995-2014. We further examined factors that may modify these associations, including age, sex, hospital visit type and season.

METHODS

Using a case-crossover design with distributed lag non-linear DTR terms (0-6 days), we estimated associations between ZIP Code-level DTR and hospital visits for mood (4.6 million hospital visits), anxiety (2.4 million), adjustment (∼368,000), and schizophrenia disorders (∼211,000), controlling for daily mean temperature, via conditional logistic regression models. We assessed potential heterogeneity by age, sex, hospital visit type (in-patient vs. out-patient), and season (summer, winter, and transition seasons).

RESULTS

For all included outcomes, we observed positive associations from period minimum DTR (0.1°C) until 25th percentile (5.2°C) and between mean DTR (7.7°C) and 90th percentile (12.2°C), beyond which we observed negative associations. For mood disorders, an increase in DTR from 0.1°C to 12.2°C was associated with a cumulative 16.0% increase (95% confidence interval [CI]: 12.8, 19.2%) in hospital visit rates. This increase was highest during transition seasons (32.5%; 95%CI: 26.4, 39.0%) compared with summer (10.7%; 95%CI: 4.8, 16.8%) and winter (-1.6%; 95%CI: -7.6, 4.7%). For adjustment and schizophrenia disorders, the strongest associations were seen among the youngest group (0-24 years) with almost no association in the oldest group (65+ years). We observed no evidence for modification by sex and hospital visit type.

DISCUSSION

Daily temperature variability was positively associated with mental health-related hospital visits within specific DTR ranges in New York State, after controlling for daily mean temperature. Given uncertainty on how climate change modifies temperature variability, additional research is crucial to comprehend the implications of these findings, particularly under different scenarios of future temperature variability.

Clinical, sociodemographic and environmental predicting factors for relapse in bipolar disorder: A systematic review

INTRODUCTION

Bipolar disorder (BD) is a chronic and recurrent illness characterized by manic, mixed or depressive episodes, alternated with periods of euthymia. Several prognostic factors are associated with higher rates of relapse, which is crucial for the identification of high-risk individuals. This study aimed at systematically reviewing the existing literature regarding the impact of sociodemographic, clinical and environmental factors, in clinical relapses, recurrences and hospitalizations due to mood episodes in BD.

METHODS

A systematic search of electronic databases (PubMed, Cochrane library and Web of Science) was conducted to integrate current evidence about the impact of specific risk factors in these outcomes.

RESULTS

Fifty-eight articles met the inclusion criteria. Studies were grouped by the type of factors assessed. Family and personal psychiatric history, more severe previous episodes, earlier age of onset, and history of rapid cycling are associated with clinical relapses, along with lower global functioning and cognitive impairments. Unemployment, low educational status, poorer social adjustment and life events are also associated with higher frequency of episodes, and cannabis with a higher likelihood for rehospitalization.

LIMITATIONS

Small sample sizes, absence of randomized clinical trials, diverse follow-up periods, lack of control for some confounding factors, heterogeneous study designs and diverse clinical outcomes.

CONCLUSIONS

Although current evidence remains controversial, several factors have been associated with an impaired prognosis, which might allow clinicians to identify patients at higher risk for adverse clinical outcomes and find modifiable factors. Further research is needed to elucidate the impact of each risk factor in the mentioned outcomes.

Mental health and air temperature: Attributable risk analysis for schizophrenia hospital admissions in arid urban climates

Health researchers have examined the physiological impacts of extreme air temperature on the human body. Yet, the mental health impacts of temperature have been understudied. Research has shown that the environment can create circumstances that exacerbate mental health issues. This may be particularly challenging for some of the fastest growing cities, located in hot, dry climates. Given the theoretical relationship between air temperature and mental health, we seek to measure the association between temperature and schizophrenia hospital admissions in an arid urban climate and quantify the associated public health burden. We collected 86,672 hospitalization records for schizophrenia from 2006 to 2014 in Maricopa County, Arizona, USA. Using a distributed lag non-linear model (DLNM), we tested for a statistical association between temperature and schizophrenia hospital admissions after controlling for year, season, weekends, and holidays. We calculated the cumulative attributable risk of nighttime temperature on schizophrenia for the entire dataset as well as among demographic subgroups. The relative risk of schizophrenia hospital admissions increased with both high and low temperatures. Statistical models using daily minimum temperature were more strongly associated with hospitalization than those using mean or maximum. Schizophrenia hospital admissions increased on days with minimum temperatures above 30 °C and below 3 °C, with some subgroups experiencing higher rates of hospitalization. The total fraction of schizophrenia hospital admissions attributable to non-optimal minimum temperature is 3.45 % (CI: -4.91-10.80 %) and high minimum temperature is 0.28 % (CI: -1.18-1.78 %). We found that non-whites and males appear to be at a slightly increased risk than the general population, although there did not appear to be a statistically significant difference. A conservative estimate of healthcare costs annually from non-optimal temperature attributed schizophrenia hospitalization is $1.95 million USD. Therefore, nighttime cooling strategies and efforts could increase the accessibility of shelters to reduce overnight exposure to extreme air temperature.

Long-Term Apparent Temperature, Extreme Temperature Exposure, and Depressive Symptoms: A Longitudinal Study in China

Temperature is increasingly understood to impact mental health. However, evidence of the long-term effect of temperature exposure on the risk of depressive symptoms is still scarce. Based on the China Health and Retirement Longitudinal Study (CHARLS), this study estimated associations between long-term apparent temperature, extreme temperature, and depressive symptoms in middle-aged and older adults. Results showed that a 1 °C increase or decrease from optimum apparent temperature (12.72 °C) was associated with a 2.7% (95% CI: 1.3%, 4.1%) and 2.3% (95% CI: 1.1%, 3.5%) increased risk of depressive symptoms, respectively. This study also found that each percent increase in annual change in ice days, cool nights, cool days, cold spell durations, and tropical nights was associated with higher risk of depressive symptoms, with HRs (95%CI) of 1.289 (1.114-1.491), 2.064 (1.507-2.825), 1.315 (1.061-1.631), 1.645 (1.306-2.072), and 1.344 (1.127-1.602), respectively. The results also indicated that people living in northern China have attenuated risk of low apparent temperature. Older people were also observed at higher risk relating to more cool nights. Middle-aged people, rural residents, and people with lower household income might have higher related risk of depressive symptoms due to increased tropical nights. Given the dual effect of climate change and global aging, these findings have great significance for policy making and adaptive strategies for long-term temperature and extreme temperature exposure.

Climate change and mental health research methods, gaps, and priorities: a scoping review

Research on climate change and mental health is a new but rapidly growing field. To summarise key advances and gaps in the current state of climate change and mental health studies, we conducted a scoping review that comprehensively examined research methodologies using large-scale datasets. We identified 56 eligible articles published in Embase, PubMed, PsycInfo, and Web of Science between Jan 1, 2000, and Aug 9, 2020. The primary data collection method used was surveys, which focused on self-reported mental health effects due to acute and subacute climate events. Other approaches used administrative health records to study the effect of environmental temperature on hospital admissions for mental health conditions, and national vital statistics to assess the relationship between environmental temperature and suicide rates with regression analyses. Our work highlights the need to link population-based mental health outcome databases to weather data for causal inference. Collaborations between mental health providers and data scientists can guide the formation of clinically relevant research questions on climate change.

Is there an association between hot weather and poor mental health outcomes? A systematic review and meta-analysis

BACKGROUND

Mental health is an important public health issue globally. A potential link between heat exposure and mental health outcomes has been recognised in the scientific literature; however, the associations between heat exposure (both high ambient temperatures and heatwaves) and mental health-related mortality and morbidity vary between studies and locations.

OBJECTIVE

To fill gaps in knowledge, this systematic review aims to summarize the epidemiological evidence and investigate the quantitative effects of high ambient temperatures and heatwaves on mental health-related mortality and morbidity outcomes, while exploring sources of heterogeneity.

METHODS

A systematic search of peer-reviewed epidemiological studies on heat exposure and mental health outcomes published between January 1990 and November 2020 was conducted using five databases (PubMed, Embase, Scopus, Web of Science and PsycINFO). We included studies that examined the association between high ambient temperatures and/or heatwaves and mental health-related mortality and morbidity (e.g. hospital admissions and emergency department visits) in the general population. A range of mental health conditions were defined using ICD-10 classifications. We performed random effects meta-analysis to summarize the relative risks (RRs) in mental health outcomes per 1 °C increase in temperature, and under different heatwaves definitions. We further evaluated whether variables such as age, sex, socioeconomic status, and climate zone may explain the observed heterogeneity.

RESULTS

The keyword search yielded 4560 citations from which we identified 53 high temperatures/heatwaves studies that comprised over 1.7 million mental health-related mortality and 1.9 million morbidity cases in total. Our findings suggest associations between heat exposures and a range of mental health-related outcomes. Regarding high temperatures, our meta-analysis of study findings showed that for each 1 °C increase in temperature, the mental health-related mortality and morbidity increased with a RR of 1.022 (95%CI: 1.015-1.029) and 1.009 (95%CI: 1.007-1.015), respectively. The greatest mortality risk was attributed to substance-related mental disorders (RR, 1.046; 95%CI: 0.991-1.101), followed by organic mental disorders (RR, 1.033; 95%CI: 1.020-1.046). A 1 °C temperature rise was also associated with a significant increase in morbidity such as mood disorders, organic mental disorders, schizophrenia, neurotic and anxiety disorders. Findings suggest evidence of vulnerability for populations living in tropical and subtropical climate zones, and for people aged more than 65 years. There were significant moderate and high heterogeneities between effect estimates in overall mortality and morbidity categories, respectively. Lower heterogeneity was noted in some subgroups. The magnitude of the effect estimates for heatwaves varied depending on definitions used. The highest effect estimates for mental health-related morbidity was observed when heatwaves were defined as "mean temperature ≥90th percentile for ≥3 days" (RR, 1.753; 95%CI: 0.567-5.421), and a significant effect was also observed when the definition was "mean temperature ≥95th percentile for ≥3 days", with a RR of 1.064 (95%CI: 1.006-1.123).

CONCLUSIONS

Our findings support the hypothesis of a positive association between elevated ambient temperatures and/or heatwaves and adverse mental health outcomes. This problem will likely increase with a warming climate, especially in the context of climate change. Further high-quality studies are needed to identify modifying factors of heat impacts.

Weather and Aggressive Behavior among Patients in Psychiatric Hospitals-An Exploratory Study

Background: The number of meteoropaths, or people negatively affected by weather conditions, is rising dramatically. Meteoropathy is developing rapidly due to ever poorer adaptations of people to changes in weather conditions. Strong weather stimuli may not only exacerbate symptoms in people with diseases of the cardiovascular and respiratory systems but may also induce aggressive behavior. Researchers have shown that patients suffering from mental illnesses are most vulnerable to changes in the weather and postulate a connection between the seasons and aggressive behavior. Methods: The goal of the study was to analyze the relationship between coercive measures and weather factors. The researchers identified what meteorological conditions prevailed on days with an increased number of incidents of aggressive behavior leading to the use of physical coercion towards patients in a psychiatric hospital in Poland. In order to determine the impact of weather conditions on the frequency at which physical coercion measures were used, the hospital’s “coercion sheets” from 1 January 2015 to 31 March 2017 were analyzed. The data were correlated with meteorological data. In order to determine the relationship between the occurrence of specific weather conditions and the number of coercive interventions (N), researchers utilized Spearman’s rank correlation analysis together with two-dimensional scatter diagrams (dependency models), multiple regression, stepwise regression, frequencies, and conditional probability (%). Results: Lower barometric pressure and foehn wind increased aggressive behavior in patients that led to coercive measures. For temperature (positive correlation) and humidity (negative correlation), there was a poor but statistically significant correlation. Conclusions: Monitoring weather conditions might be useful in predicting and preventing aggression by patients who are susceptible to weather changes

What is the role of meteorological variables on involuntary admission in psychiatric ward? An Italian cross-sectional study

Weather affects physical and mental health through several modalities which are not fully elucidated. The aim of the present study was to investigate the impact of meteorological variables and other indexes in a large sample of hospitalized patients, focusing on subjects who were involuntarily admitted. We hypothesized a direct relation between the amount of involuntary admissions and mean sunshine hours. Furthermore, we supposed that specific meteorological factors may significantly influence hospitalizations of patients affected by severe psychiatric conditions. All subjects were consecutively recruited from the Psychiatric Inpatient Unit of San Luigi Gonzaga Hospital, Orbassano (Turin, Italy) from September 2013 to August 2015. Socio-demographic and clinical characteristics were carefully collected. Meteorological data were derived by the Italian Meteorology's Climate Data Service of Physics Department of the University of Turin (Latitude: 45°03'07,15″ Nord, Longitude: 007°40'53,30″ Est, Altitude: 254 m above the sea level) (http://www.meteo.dfg.unito.it/). Our data indicate significant differences regarding temperature (minimum, maximum, and medium), solar radiation, humidex and windchill index, and hours of sunshine in psychiatric patients who were involuntarily hospitalized. After logistic regression analyses, only maximum and medium temperature, and humidex index remained significantly associated with involuntary admission in an emergency psychiatric ward. The limitations of this study include the cross-sectional study design and the single hospital for patients' recruitment. Furthermore, results and seasonal patterns obtained by patients requiring hospitalization might significantly differ from those who were not hospitalized. Exploring in a more detailed manner those environmental factors associated with involuntary admissions could lead to early intervention and prevention strategies for such distressing hospitalizations.

Association Between Surrounding Greenness and Schizophrenia: A Taiwanese Cohort Study

This study aims to investigate the association between surrounding greenness and schizophrenia incidence in Taiwan. Data of 869,484 individuals without a history of schizophrenia were included from the Longitudinal Health Insurance Database from 2000 through 2010 for analysis. The diagnoses of schizophrenia were based on ICD-9 codes. Greenness exposure was assessed using the satellite-based normalized difference vegetation index, assuming individuals lived near the hospital they most often visited for common cold during the study period. Cox proportional hazards models were applied to assess the association between greenness exposure and schizophrenia incidence after adjustments were made for the potential confounders. A total of 5,069 schizophrenia cases were newly diagnosed during the study period. A negative significant (p < 0.05) association found using 2000-m buffer distances (distance of a moderately paced 20-min walk) in the whole Taiwan island, cities, and metropolitan areas. The results of the stratified analysis based on sex and health insurance rate suggested surrounding greenness has approximately equal effects of reducing the risk of schizophrenia, regardless of sex or financial status. In conclusion, our findings suggest that more surrounding greenness may reduce the risk of schizophrenia.

Maximum Temperature and Solar Radiation as Predictors of Bipolar Patient Admission in an Emergency Psychiatric Ward

Environmental variables can regulate behavior in healthy subjects. Recently, some authors investigated the role of meteorological variables in bipolar patients with an impact on both the onset and course of bipolar disorder (BD). The aim of this study was to investigate the impact of meteorological variables and other indexes in bipolar hospitalized patients. We examined all patients admitted to the Psychiatric Inpatient Unit of San Luigi Gonzaga Hospital, Orbassano (Turin, Italy) from September 2013 to August 2015, collecting several socio-demographic and clinical characteristics. Seven hundred and thirty patients were included. Compared to the day of admission of control individuals, patients with BD were admitted on a day that presented higher minimum, medium, and maximum temperature, higher maximum humidity, higher solar radiation, and higher hours of sunshine. After logistic regression analysis, admissions to the emergency psychiatric ward due to a primary diagnosis of BD were associated with maximum temperature and solar radiation. The current study provides a novel perspective on the question surrounding seasonal mood patterns in patients with BD. A greater awareness of all possible precipitating factors is needed to inform self-management and psycho-educational programs as well as to improve resilience regarding affective recurrences in the clinical practice.

Factors affecting time to remission for inpatients with bipolar mania - A naturalistic Taiwanese study

BACKGROUND

Bipolar disorder is a complicated and chronic mental disorder. This study investigated factors affecting time to remission for inpatients with bipolar mania after 4 weeks of acute treatment.

METHODS

This naturalistic study recruited inpatients with bipolar mania for acute treatment. Symptom severity was assessed using the Young Mania Rating Scale (YMRS) at weeks 0, 1, 2, 3, and 4. Patients were included if they had had assessments at weeks 0 and 1 Remission was defined as an YMRS score ≤ 12. The Cox regression analysis was used to analyze factors associated with time to remission after 4 weeks of acute treatment.

RESULTS

Four hundred and forty-nine patients entered the analysis. Seventy-one of the 449 subjects (15.8%) reached symptomatic remission within 4 weeks of acute treatment. Using forward multivariate Cox regression analysis, comorbid substance use disorders, earlier age at onset, and greater manic symptom severity at baseline found to be statistically significant predictors of a longer time to reach remission after 4 weeks of treatment.

LIMITATIONS

As a retrospective chart review and naturalistic design, placebo effect and potentially confounding factors such as the possibility of missing records may have limited our results.

CONCLUSIONS

Early identification and intervention with integrated therapy is considered to shorten time to remission for patients at high risk of poor treatment outcome. More studies are needed in other real-world settings to generalize our results.

Suicide and meteorological factors in São Paulo, Brazil, 1996-2011: a time series analysis

Objective:

Considering the scarcity of reports from intertropical latitudes and the Southern Hemisphere, we aimed to examine the association between meteorological factors and suicide in São Paulo.

Method:

Weekly suicide records stratified by sex were gathered. Weekly averages for minimum, mean, and maximum temperature (°C), insolation (hours), irradiation (MJ/m²), relative humidity (%), atmospheric pressure (mmHg), and rainfall (mm) were computed. The time structures of explanatory variables were modeled by polynomial distributed lag applied to the generalized additive model. The model controlled for long-term trends and selected meteorological factors.

Results:

The total number of suicides was 6,600 (5,073 for men), an average of 6.7 suicides per week (8.7 for men and 2.0 for women). For overall suicides and among men, effects were predominantly acute and statistically significant only at lag 0. Weekly average minimum temperature had the greatest effect on suicide; there was a 2.28% increase (95%CI 0.90-3.69) in total suicides and a 2.37% increase (95%CI 0.82-3.96) among male suicides with each 1 °C increase.

Conclusion:

This study suggests that an increase in weekly average minimum temperature has a short-term effect on suicide in São Paulo.