The Relationship Between Meteorological Conditions and Homicide, Suicide, Rage, and Psychiatric Hospitalization

J Forensic Sci,2014 doi: 10.1111/1556-4029.12471 TECHNICAL NOTE Available online at: onlinelibrary.wiley.com PSYCHIATRY AND BEHAVIORAL SCIENCES

Ali Talaei,1 M.D.; Arya Hedjazi,2 M.D.; Amir Rezaei Ardani,1 M.D.; Mohammad Reza Fayyazi Bordbar,1 M.D.; and Andisheh Talaei,3

The Relationship between Meteorological Conditions and Homicide, Suicide, Rage, and Psychiatric Hospitalization

ABSTRACT: This study focuses on the relationship between the incidence of homicide, rage, suicide, and psychiatric hospitalization as violent behaviors with temperature, humidity, and air pressure as specific meteorological variables in the city of Mashhad, in the northeast of Iran. The data were obtained from Iran Meteorological Organization, official registry of Legal Medicine Organization and the local psychiatric hospital, March 2009 to Feb 2010 daily and were analyzed with SPSS-14 using Pearson correlation coefficient, ANOVA, and post hoc analysis tests. The rates of rage and psychiatric admission had a significant relationship with the daily mean air temperature, minimum relative humidity, maximum relative humidity, minimum daily pressure, and maximum daily air pressure (p < 0.0001). There was no significant correlation between homicide and suicide rates with any meteorological variables (p > 0.05). We concluded that, the possibility of nonfatal violence and psychiatric hospitalization would increase in hot and arid weather with low air pressure.

KEYWORDS: forensic sciences, homicide, hospitalization, meteorological factors, psychiatry, rage, suicide

The controversy still remains in medical forums as to the link mitting suicide, and aggressive behaviors (3,21–25). Others between meteorological parameters and the incidence of psychi- found a relationship between solar activity and the rate of sui- atric disorders (1–5). Over the past few years, attempts have cide and mental disorders (26–29). Air pollution, apart from its been made to investigate the still unknown mechanisms whereby widely known adverse impact on respiratory system, can also weather can influence the onset and course of various medical raise depression and suicide rates (30,31). Similar patterns exist conditions, namely organic brain syndromes, cardiopulmonary with regard to the link between psychiatric abnormalities and diseases as well as hospitalization due to acute neurological dis- rainfall and humidity (3,21,22). Nevertheless, attempts failed as orders (6–12). Initial studies had have shown that wind and to the establishment of a correlation between meteorological related variables, such as speed and direction, can affect the variables and the incidence of psychiatric disorders (32–34). mental well-being of patients (13,14); many studies conducted in Indeed, some researchers have emphasized the contributory role the field of biopsychiatric research, emphasized on meteorologi- of seasonal fluctuations in the onset of psychiatric problems such cal factors such as temperature, humidity, hours of sunlight, as mood disorders, schizophrenia spectrum disorders, suicidal wind, cloudy days, and air pressure (15–17), yet few regard the attempts, assaults, and rapes (1,2,18,27,28,35–38). effect of barometric pressure on human mental activity. Based Also, it is widely believed that there is a relationship between on these findings, the incidence of psychiatric complications weather conditions and emergency department visits (30,33,39). especially suicidal behavior correlates positively with extremely Based on years of clinical experience, it seems that there is a high atmospheric pressure (18,19), as well as ozone hole season- relationship between certain periods of the year and psychiatric ality (20). Other specific meteorological parameters may also hospitalizations. This can be explained by sensitivity to different contribute to the increased risk of psychiatric disorders in sus- meteorological factors (40,41). ceptible individuals. Few studies have shown a correlation There are many environmental factors with a possible effect between temperature and winter depression, panic disorder, com- on the brain function, hence affecting human ideas, plans, and actions. The more we find out about them, the more we can dis- tinguish between human normal and abnormal behaviors. Sui- 1Psychiatry and Behavioral Sciences Research Center, Mashhad University cide, murder, and violence are preventable abnormal psychiatric of Medical Sciences, Mashhad, Iran. conditions, which always require urgent clinical intervention (7). 2Legal Medicine Research Center, Legal Medicine Organization, Tehran, This study, the first nationwide, was intended to investigate Iran. 3 the possible impacts of weather on psychological health as one Faculty of Biotechnology, Tehran University, Tehran, Iran. of the less well-known environmental variables. The focus has [Correction added on April 18, 2014 after first online publication: Author affiliations have been corrected and updated from the originally posted version.] been on homicide, rage, suicide, and psychiatric hospitalization Received 22 Sept. 2012; and in revised form 5 July 2013; accepted 28 in relation to temperature, humidity, and air pressure as specific July 2013. meteorological variables.

Materials and Methods Results In this retrospective study, the role of meteorological variables The average number of rages per day was 93.85 Æ 49.69 (0– (temperature, relative humidity, and barometric pressure) on the 233 rages/day). In a sharp contrast with homicide with incidence of violent crimes (rage, suicide, and homicide) and 0.17 Æ 0.45 per day (0–3/day), average pertaining to suicide psychiatric hospitalization was evaluated in the city of Mashhad, and psychiatric hospitalization were 0.21 Æ 0.49 per day (0–3 in the northeast of Iran. attempts/day) and 9.83 Æ 9.83 per day (0–26 cases/day), respec- The study was carried out with the approval of Ethics Com- tively. mittee of Mashhad University of Medical Sciences as medical Mean daily temperature ranged from À5 to 30.5°C on differ- doctorate thesis. ent days. This spectrum of daily temperature was divided into Temperature, as an indicator of how hot or cold a physical four following groups: environment is, is often shown by degrees in Celsius or Fahr- • Group 1: À5to<4°C enheit scales. Relative humidity, the concentration of water • Group 2: 4 to <13°C vapor in the air, is expressed in percent. High relative humid- • Group 3: 13 to <22°C ity can make the weather feel warmer than it actually is • Group 4: 22 to <31°C because it decreases the coldness felt by evaporation from the skin. Atmospheric pressure is the pressure exerted by the Table 1 shows the distribution of variations in the four earth’s atmosphere at any given point, the product of the mass groups. of the atmospheric column of the unit area above the given Daily mean air temperature was shown to be directly affecting point. The larger the mass, the higher the pressure. Changes the rate of rage (p < 0.0001, F = 51.586) and hospitalization in atmospheric pressure correlate with local weather condi- (p < 0.0001, F = 18.931). However, neither homicide (p = 0.43, tions. High- and low-pressure areas are often identified with F = 0.923) nor suicide (p = 0.61, F = 0.603) was correlated good and bad weather conditions, respectively. Atmospheric with this variable in any of the four groups (Table 1). pressure is expressed in millimeters of mercury (mmHg) in The minimum relative humidity in 2005 was reported between this study. 4 and 100%, depending on the season and climate change. It The meteorological data in Mashhad were obtained from was quantitatively divided into four groups as follows: Information Technology (IT) department of Iran Meteorological • Group 1: 4% to <28% Organization (March 2009 to Feb 2010 daily). • Group 2: 28% to <52% Violent behaviors in this study include rage, suicide, and • Group 3: 52% to <76% homicide. Rage is a hostile physical contact between people, • Group 4: 76% to 100% whereas suicide is an act of self-harm intended to take one’s own life, which can be either successful (completed) or unsuc- Table 2 shows the distribution of variations in the four groups cessful (attempted). In this study, we covered the former. On the based on minimum daily humidity. other hand, homicide is a successful act of killing another human The rage (p < 0.0001, F = 21.224) and hospitalization rate being. Our data were obtained from two chief sources, which (p < 0.0001, F = 8.254) had a significant negative correlation were also in concordance with each other. Cases of rage, suicidal with minimum relative humidity. There was no significant rela- attempts, and homicide were extracted from the official registry tionship between homicide (p = 0.28, F = 1.272) and suicide of Legal Medicine Organization, March 2009 to Feb 2010. Both rate (p = 0.82, F = 0.313) and minimum relative humidity in the the report and registration took place on a daily basis. Psychiat- four different groups (Table 2). ric emergency ward admissions in Ibn-e-Sina Hospital, affiliated to the Medical University of Mashhad, were also reported. It is noteworthy that it is the only hospital with a psychiatric emer- TABLE 1––The distribution of variations in groups of struggle, murder, gency ward. suicide, and hospitalization (temperature data are in centigrade). The exact date of committing suicide, rage, and homicide could easily be determined via extracting the date reported by Temperature either the local psychiatric hospital or the local office of Legal À – ° – ° – ° – ° Medicine Organization. Variable 5 3.9 C412.9 C1321.9 C2230.9 C To evaluate the correlation between violent behavior and hos- Rage 66 76 112 121 pital admissions with meteorological variables (temperature, Homicide 0.17 0.2 0.1 0.15 humidity, and barometric pressure), each of the variables of Suicide 0.16 0.22 0.23 0.15 Hospitalization 7.4 8.3 11.4 11.9 barometric pressure, temperature, and humidity were divided into four distinct groups, based on the results obtained from the Information Technology (IT) department of Iran Meteorological –– Organization. This will be further delineated in the results sec- TABLE 2 The distribution of variations in groups of struggle, murder, suicide, and hospitalization with the minimum daily humidity in terms of tion. The frequency of the main variables (violent behavior and percent. hospital admissions) in each of the distinct groups was subse- quently determined, enabling us to compare the frequency of the Minimum Daily Humidity main variables (violent behaviors and hospital admissions) in different groups for each meteorological variable in this study. Variable 4–27 28–51 52–75 76–100 The data were analyzed using SPSS software, version 14 Rage 115 103 86 71 (Mashhad University of Medical Sciences, Mashhad, Iran). Pear- Homicide 0.12 0.17 0.22 0.11 son correlation coefficient, ANOVA, and post hoc analysis tests Suicide 0.23 0.25 0.21 0.18 were also used to compare data sets. Hospitalization 11 11 9 7 ALI TALAEI ET AL. . METEOROLOGICAL CONDITIONS AND VIOLENT BEHAVIOURS 3

TABLE 3––The distribution of variations in groups of struggle, murder, sui- TABLE 5––The distribution of variations in groups of struggle, murder, suicide, and hospitalization with the maximum daily humidity in terms of per- cide, and hospitalization with the maximum daily pressure in terms mmHg. cent. Maximum Daily Pressure Maximum Daily Humidity Variable 994–1007 1008–1021 1022–1035 1036–1050 Variable 16–36 37–57 58–78 79–100 Rage 122 97 83 72 Rage 118 106 77 74 Homicide 0.16 0.11 0.17 0.24 Homicide 0.11 0.19 0.18 0.14 Suicide 0.25 0.17 0.17 0.27 Suicide 0.19 0.26 0.25 0.16 Hospitalization 11 10 9 8 Hospitalization 11 11.3 8.5 8.1

again, homicide (p = 0.32, F = 1.176) and suicide (p = 0.35, As to maximum relative humidity in the same year, values F = 1.105) remained largely unaffected in the comparison. varied between 16 and 100%, presented in four groups: • Group 1: 16% to <37% Discussion • Group 2: 37% to <58% • Group 3: 58% to <79% The average number of rages, homicides, and suicides Æ Æ • Group 4: 79% to 100% occurred over a day was 93.85 49.69, 0.17 0.45, and 21 Æ 0.49, respectively. The average number of psychiatric hos- Table 3 shows the distribution of variations in the four groups pitalizations was 9.83 Æ 9.83 per day. in terms of daily maximum relative humidity. Daily mean air temperature was registered from À5 to 30.5°C. As can be seen, rages (p < 0.0001 and F = 27.908) and hos- The minimum and maximum relative humidity values (daily) pitalization (p < 0.0001 and F = 9.220) were negatively affected were between 4–100% and 16–100% on different days, respec- by this factor, whereas in cases of suicide (p = 0.50 and tively. F = 0.783) and homicide (p = 0.45 and F = 0.697), no signifi- The minimum and maximum daily barometric pressure values cant correlation was found (Table 3). ranged from 891.30 to 917.20 mmHg and from 995.00 to Daily minimum atmospheric pressure was ranging from 1049.00 mmHg, respectively. 891.30 to 917.20 mmHg in 2005. Values were presented in four According to the findings, the rates of rage and hospitalization categories as follows: rate were directly related to daily mean air temperature, inversely • Group 1: 890 to <897 mmHg correlated with minimum and maximum relative humidity, and • Group 2: 897 to <904 mmHg negatively correlated with minimum and maximum daily atmo- • Group 3: 904 to <911 mmHg spheric pressure. However, these meteorological parameters • Group 4: 911 to 918 mmHg failed to affect either homicide or suicide rates. For years, the association between air temperature and aggres- As can be seen in the distribution of varieties in Table 4, rage sive behavior has been the focus of attention (17,24,42,43). In (p < 0.0001, F = 10.807) and hospitalization rates (p = 0.03, 1980s, a close relationship was demonstrated between assaults F = 2.980) were inversely correlated with daily minimum pres- and rapes with temperature in different geographical locations in sure, whereas homicide (p = 0.14, F = 1.186) and suicide rates the United States (38). It was shown that violent crimes were (p = 0.28, F = 1.286) were shown immune to such alterations. more prevalent in the hotter quarters of the year and also in hot- The last but not the least parameter in case was maximum ter years. Furthermore, temperature–crime relation was stronger barometric pressure, ranging from 995 to 1049 mmHg in the in cases of violent than nonviolent crimes (17,24,42). These specific period. Variations were presented in four groups as in findings were examined in the late 1990s with more or less simi- the following: lar outcomes (44). A rise in the degree of violence was shown • Group 1: 994 to <1008 mmHg to be positively correlated with the increasing number of hot • Group 2: 1008 to <1022 mmHg days. • Group 3: 1022 to < 1036 mmHg By definition, a hot day is when the mean daily temperature º ° • Group 4: 1036 to 1050 mmHg exceeds 90 Fahrenheit (32.2 C), higher than the maximum average temperature of any given day throughout the specified time Table 5 shows the significant negative correlation between the bracket. Both the positive linear and inverted U-shaped relation- incidence of rage (p < 0.0001, F = 28.061) and hospitalization ships between the temperature and aggression have been dis- (p < 0.0001, F = 8.973) and maximum barometric pressure. Yet cussed in literature (45–48). In contrast, there is no general consensus as to how temperature can affect homicide rates. A view stipulates that higher mean ambient temperature is associ- –– TABLE 4 The distribution of variations in groups of struggle, murder, sui- ated with increased murder as violence and aggression soar par- cide, and hospitalization with the minimum daily pressure in terms of mmHg. allel with rise in temperature (24). Results of some studies showed that the rate of suicide has a direct correlation with tem- Minimum Daily Pressure perature (25). However, other research failed to establish any obvious corre- Variable 890–896.99 897–903.99 904–910.99 911–917.99 lation between temperature changes and homicide rate, as was Rage 46.6 44.5 35.9 35.5 observed in our study (38,49). Homicide 0.4 0.3 0.4 0.5 Generally, there is no clear relationship between weather con- Suicide 0.5 0.4 0.4 0.6 ditions and emergency department attendance. In some studies, a Hospitalization 5.4 4.9 5.4 4.9 positive correlation has been found between the number of 4 JOURNAL OF FORENSIC SCIENCES admissions and “good weather” (warm, dry, sunny weather) Nevertheless, psychiatric emergency referrals were reported to (30,33). On the other hand, some research has shown that be significantly higher than expected on days with lower air patients are more frequently admitted to hospitals in bad weather pressure (63). Likewise, we could not find any clear association especially when temperature is low (30,39). However, our find- between the rate of homicide and barometric pressure. ings were similar to those with a focus on psychiatric patients. A recent study in the United States confirmed past findings It has been proposed that higher temperature could interfere with regard to the absence of any correlation behavior and with sleep continuity (50). High environmental temperature may humidity (69). Yet, we managed to establish a reverse correla- precipitate psychotic exacerbations in schizophrenic patients and tion between humidity and rage. It is difficult to compare our thus increase their admission to mental hospitals (1). Rise in findings in Mashhad and those of North America cities owing to mean daily temperature may also contribute to major depressive the relative aridity of the former place. In the present study, episodes in patients with bipolar disorder, possibly necessitating there could be found a significant relationship between psychiat- hospitalization (2,30). Moreover, a significant relationship was ric hospitalization and precipitation. Nevertheless, this was lar- shown between parasuicide rate and meteorological factors (5). gely defied by other studies (32,63). Nevertheless, some authors believe that further work is needed Murder and humidity were also shown unrelated to each to clarify the impact of meteorological factors on psychiatric other, as they were in others’ findings. hospitalization. They suggest that meteorological parameters may In Singapore, climatic variables such as temperature and influence the availability of medical facilities. For instance, humidity were shown to be significantly correlated with suicide attendance via ambulance was not shown to be affected by in young adults’ subgroups (21). In England, according to a weather variables in any medical emergency (33). In addition, research investigating the elderly population, a positive associa- bipolar depressed admission rates may increase in winter (32). tion was demonstrated between suicide rates and relative humid- Given the fact that schizophrenia admissions were not shown to ity (70). The same results were obtained from a general be rising in the summer months, they must be unrelated to any population survey carried out in Turkey (56). Inversely, official other climate change all throughout the year (51). data retrieved from the suicide cases in other European countries The impact of climate change on suicide has been observed in showed that the risk of suicide was significantly higher on days many populations (29,36,51–55). Generally, data have shown with lower relative humidity (22,57,71). Our findings are differ- that the risk of committing suicide is significantly higher on the ent from the above-mentioned in that there could be found no days with high temperature (19,22,25,53,56–59). However, there correlation between humidity and suicide (13). are other studies that tend to emphasize the correlation between suicide incidents and the number of sunny hours as well as Conclusion higher ambient temperature (35,36). Other studies discussed violent and nonviolent suicides separately (17). It is probable that This study investigated the potential correlation between a only violent suicides are associated with the changes in ambient number of meteorological factors, namely daily mean air temper- temperature and light–dark span (17,60,61). Overall, there could ature, minimum and maximum relative humidity and minimum be found no specific association between different weather con- and maximum daily barometric pressure variations, and the rates ditions and the risk of committing suicide (62). of rages, psychiatric hospitalizations, homicides, and suicides There is paucity of research into the effects of air pressure over a 1-year period. and precipitation on mental activity and human behavior. According to the results, we concluded that the possibility of According to a study conducted in the United States in 1999, nonfatal violence and psychiatric hospitalization would increase there was a reverse correlation between air pressure and violent in hot and arid weather with low air pressure, but it seems that crimes (63). Other studies reported a relationship between homi- homicide and suicide rates bear no correlation with above-men- cides and season as well as days of the week (64). Previously, tioned meteorological variables. significant correlations were suggested between barometric pres- There are some interesting questions which could be the focus sure changes and behavioral variables in mentally retarded males of attention in future studies. One is the cumulative effect of the (65). Over the last decade, a few studies have also suggested meteorological factors on the presence of violence. It seems that possible changes in the cerebrospinal fluid metabolite levels of changes in any environmental factors take a reasonable time to 5-hydroxyindoleacetic acid (5-HIAA), which was also parallel to influence the brain function, including different types of behav- changes in climatic alterations. In depressed patients, it was ior such as violence. As a result, it is important to study the cor- shown that a decrease in the air pressure is correlated with an relation of the changes in meteorological variables over a certain increase in the cerebrospinal fluid 5-HIAA levels, which may, in period of time alongside the following incidence of homicide, turn, lead to an increase in social violence (66), although is diffi- suicide, and rage. cult to explain this correlation (67). In addition, differentiating the underlying causes of the violent In a research study in Germany in 1986 highlighted that sig- behavior (such as personality traits, psychotic disorders, mood nificantly fewer suicide attempts were reported in days on which disorders, etc.) would be very helpful to a better understanding air pressure had been lower (68). A few recent investigations of the possible relations between meteorological variables and have also shown that suicide rates were higher on days with the presence of different types of violence. extreme atmospheric pressure (19). Conversely, a 5-year study in Turkey reported that atmospheric pressure was negatively corre- Limitations lated with the number of suicide attempts (56). This is what we cannot corroborate in our study. Interestingly, many studies This study had some limitations. First, we could not evaluate failed to specify a correlation between barometric pressure and the underlying causes of violence, suicide, homicide, and rages, suicidal behaviors (63). such as psychotic disorder and problems arising from drug abuse. In the present study, hospitalization increased in the days with Second, the study was performed solely in Mashhad. This led low air pressure, which defies other findings in literature (63). to a small sample size for evaluating some of the variables. For ALI TALAEI ET AL. . METEOROLOGICAL CONDITIONS AND VIOLENT BEHAVIOURS 5 example, the rate of murder was too low, which affected the sta- 18. Gostynski M, Maczynski B, Marcinkowski JT. Meteorotropic activity of tistical evaluations. the weather conditions and their role in suicide epidemiology. I. Commu- nication (author’s transl). Zentralbl Bakteriol B 1975;161(2):158–64. [In Lastly, in our study, the data were limited to successful sui- German]. cides and not the overall suicidal attempts. 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