Seasonal variation in suicides and in admissions to hospital for mania and depression

A Systematic Review on the Impact of Seasonality on Severe Mental Illness Admissions: Does Seasonal Variation Affect Coercion?

Coercion in psychiatry is associated mainly with involuntary admissions. The purpose of this study was to investigate the associations between hospital admissions of patients suffering from affective and schizophrenic disorders and seasonality. A systematic literature search using PubMed, Scopus and Google Scholar was conducted, including studies with affective and schizophrenia disorder admissions, published from October 1992 to August 2020. A total of 31 studies were included in the review. Four broad severe mental illness admission categories were identified regarding seasonality: affective disorders, schizophrenia disorders, involuntary admission affective disorders and involuntary admission schizophrenia disorders. There was clear and strong evidence for spring and summer peaks for severe mental illness admissions; data provided for age, gender and involuntary admissions was limited. Seasonality may have a significant effect on the onset and exacerbation of psychopathology of severe mental illness and should be considered as a risk factor in psychiatric admissions, violence and the risk of mental health coercion. A better understanding of the impact of seasonality on severe mental illness will help professionals to provide the best practices in mental health services in order to reduce and prevent psychiatric hospitalizations (especially involuntary admissions) resulting in further coercive measures.

The impact of daylight on suicide rates

Since Durkheim and Morselli found a spring peak in suicides in the late 19th century, researchers have presented possible explanations, including daylight variation, for this seasonal pattern. Our identification strategy exploits the idiosyncratic variation in daylight within Norwegian regions, arising from the country's substantial latitudinal range. We use full population data for a period of 45 years in a pre-registered research design. We find a small and non-significant relationship: One extra hour of daylight increases the suicide rate by merely 0.75 % (95 % CI: -0.4 % to 1.9 %).

Seasonality in Major Depressive Disorder: Effect of Sex and Age

BACKGROUND

Aside from the concept of seasonal affective disorder, the evidence for a seasonal pattern (SP) of major depressive disorder (MDD) is controversial. Furthermore, the effect of sex and age is still unclear.

METHODS

This is a nationwide, registry-based study assessing all inpatient admissions in mental health hospitals due to MDD episodes according to ICD-10 (moderate (F32/33.1), severe (F32/33.2) and severe with psychotic features (F32/33.3)) in Austria across 14 years. Calculations were based on deviations from expected monthly admissions.

RESULTS

The sample comprised 231,824 hospitalisations (36.8% men) for MDD. A significant SP (p=0.001) in moderate and severe depressive episodes in both women and men with decreased admission rates in the summer months and December was detected. In psychotic depression a significant SP was only evidenced in women (p = 0.002, men: p = 0.291). Patients older than 55 years had a reduced SP compared to those being younger.

LIMITATIONS

Only anonymised admission data of inpatient treatments were available. Hospitalization rates cannot fully be equated to the occurrence of MDD.

CONCLUSIONS

The current study indicates a seasonal variation in MDD symptoms that may go beyond seasonal affective disorder. Knowledge about the predictability of depressive symptoms in patients should encourage preventive strategies.

Assessing evidence for seasonality of hospital admissions for schizophrenia in Queensland, Australia: a time series observational study

Most evidence on seasonal admission patterns for schizophrenia derives from the Northern Hemisphere with results from the Southern Hemisphere less documented. This study examines seasonal patterns in hospital admissions due to schizophrenia in Queensland, Australia, a large area that has a range of different climatic features. Daily hospital admissions data for people with the primary diagnosis of schizophrenia were collected from Queensland Health Department for the period from January 1996 to December 2015. A generalised linear regression model with Quasi-Poisson distribution was used to assess seasonal admission patterns across different climatic regions. The evidence for seasonality was also explored in subgroups that had different socio-demographic characteristics or history of prior hospitalisation for psychiatric disorders. Overall, a significant winter pattern (RR 1.05, 95%CI 1.01-1.13) was found with a peak in August (RR 1.08, 95%CI 1.03-1.17) in temperate Southeast Queensland. However, the hot humid North and Far North Queensland showed a peak in October (RR 1.10, 95%CI 1.02-1.22). Males (RR 1.11, 95%CI 1.07-1.14), people aged 40-59 years old (RR 1.10, 95%CI 1.05-1.15) and those who had never married (RR 1.09, 95%CI 1.06-1.12), were Australian by birth (RR 1.07, 95%CI 1.04-1.10) or were unemployed (RR 1.13, 95%CI 1.09-1.18) had significantly higher risk for hospital admissions, particularly during the winter months. The seasonal admission pattern for schizophrenia did not change significantly according to admission status and history of outpatient or community psychiatric treatment. The study found some evidence for seasonality of hospital admissions for schizophrenia that differed from northern tropical to southern temperate regions of Queensland.

Investigating the association between temperature and hospital admissions for major psychiatric diseases: A study in Greece

Evidence has emerged regarding the role of seasonality and several meteorological parameters on bipolar disorder, schizophrenia and depression. We investigated the relationship between ambient and apparent temperature and hospital admissions of major psychiatric diseases in a psychiatric clinic of a General Hospital situated in Northern Greece during 2013-19. Temperature data was provided by the National Observatory of Athens and diagnosis for psychotic, schizophrenic, manic and bipolar and unipolar depression were retrieved from medical records. A total of 783 admissions were recorded. Poisson regression models adjusted for time trends were applied to analyze the impact of temperature on monthly admissions. A summer peak was observed for the bipolar disorder, irrespectively of substance/alcohol use status. Seasonality emerged also for psychotic and schizophrenic patients with a through in winter. An increase of 1 °C in either ambient or apparent temperature was associated with an increase 1-2% in the monthly admissions in most outcomes under investigation. Alcohol and drug abuse did not modify this effect. Although our results indicate effects of temperature on psychiatric admissions, they are not consistent across subgroups populations and need to be replicated by other methodologically superior studies.

Quantifying the Effects of Climate Factors on Carbon Monoxide Poisoning: A Retrospective Study in Taiwan

Background: Carbon monoxide (CO) poisoning is the leading cause of poisoning death worldwide, but associations between CO poisoning and weather remain unclear. Objective: To quantify the influence of climate parameters (e.g., temperature, relative humidity, and wind speed) on the incidence risk of acute CO poisoning in Taiwan. Methods: We used negative binomial mixed models (NBMMs) to evaluate the influence of weather parameters on the incidence risk of acute CO poisoning. Subgroup analyses were conducted, based on the seasonality and the intentionality of acute CO poisoning cases. Results: We identified a total of 622 patients (mean age: 32.9 years old; female: 51%) with acute CO poisoning in the study hospital. Carbon monoxide poisoning was associated with temperature (beta: -0.0973, rate ratio (RR): 0.9073, p < 0.0001) but not with relative humidity (beta: 0.1290, RR: 1.1377, p = 0.0513) or wind speed (beta: -0.4195, RR: 0.6574, p = 0.0806). In the subgroup analyses, temperature was associated with the incidence of intentional CO poisoning (beta: 0.1076, RR: 1.1136, p = 0.0333) in spring and unintentional CO poisoning (beta: -0.1865, RR: 0.8299, p = 0.0184) in winter. Conclusion: Changes in temperature affect the incidence risk for acute CO poisoning, but the impact varies with different seasons and intentionality in Taiwan. Our findings quantify the effects of climate factors and provide fundamental evidence for healthcare providers to develop preventative strategies to reduce acute CO poisoning events.

Bimodal effects of sunlight on major depressive disorder

BACKGROUND

Seasonal patterns in the effect of sunlight on depression, where depression decreases when sunlight increases, have been observed in previous studies. In this study, we demonstrate a bimodal effect of sunlight on depression - short-term increases in sunlight increase depression and long-term increases in sunlight decrease depression. The analysis showed that the significant effect of sunlight is temporary and appears only when seasonal changes are severe within a given year.

METHODS

We analyzed approximately 530,000 cases where patients visited hospital for depression in Korea from January 1 to December 31, 2016. We measured the daily average amount of sunlight and daily sunlight for the 30 days previous to the day of measurement using data from 96 weather stations. To analyze the effect of sunlight, several climatic variables and local dummies were added to the negative binomial model, and the period in which the effect of sunlight was significant was derived as a term of the interaction between the month variable and sunlight.

RESULTS

When the average effects of climatic factors such as temperature, precipitation, and humidity were removed, the number of cases of depression increased when the daily average amount of sunlight increased [IRR = 1.024 (95% CI: 1.009 to 1.039)]; this effect was significant only in January and May. The number of cases of depression decreased with higher daily average sunlight for the previous 30 days increasing [IRR = 0.917 (95% CI: 0.892 to 0.944)], and this effect was significant only in January, March, and May.

CONCLUSIONS

The effect of sunlight on depression appears in both the short and long terms, but the effect is significant only for limited periods. The data examined in this study supports a pattern where short-term daily sunlight increases depression and daily sunlight for the previous 30 days decreases depression.

Prevalence of mental disorders, suicidal ideation and suicides in the general population before and during the COVID-19 pandemic in Norway: A population-based repeated cross-sectional analysis

Background

Self-report data on mental distress indicate a deterioration of population mental health in many countries during the COVID-19 pandemic. A Norwegian epidemiological diagnostic psychiatric interview survey was conducted from January to September 2020, allowing for comparison of mental disorder and suicidal ideation prevalence from before through different pandemic periods. Prevalence of suicide deaths were compared between 2020 and 2014-2018.

Methods

Participants from the Trøndelag Health Study (HUNT) in Trondheim were recruited through repeated probability sampling. Using the Composite International Diagnostic Interview (CIDI 5.0) (n = 2154), current prevalence of mental disorders and suicidal ideation was examined in repeated cross-sectional analyzes. Data on suicide deaths was retrieved from the Norwegian Cause of Death Registry and compared for the months March to May in 2014-2018 and 2020.

Findings

Prevalence of current mental disorders decreased significantly from the pre-pandemic period (January 28th to March 11th 2020; 15•3% (95% CI 12•4-18•8)) to the first pandemic period (March 12th - May 31st; 8•7% (6•8-11•0)). Prevalences were similar between the pre-pandemic period and the interim (June 1st July 31st; 14•2% (11•4-17•5)) and second periods (August 1st-September 18th; 11•9% (9•0-15•6)). No significant differences were observed in suicidal ideation or in suicide deaths.

Interpretation

Except for a decrease in mental disorders in the first pandemic period, the findings suggest stable levels of mental disorders, suicidal ideation and suicide deaths during the first six months of the COVID-19 pandemic compared to pre-pandemic levels. Potential methodological and contextual explanations of these findings compared with findings from other studies are discussed.

Funding

None.

The association between PM2.5 exposure and suicidal ideation: a prefectural panel study

Background

Suicidal ideation is subject to serious underestimation among existing public health studies. While numerous factors have been recognized in affecting suicidal thoughts and behaviors (STB), the associated environmental risks have been poorly understood. Foremost among the various environment risks were air pollution, in particular, the PM2.5. The present study attempted to examine the relationship between PM_2.5 level and local weekly index of suicidal ideation (ISI).

Methods

Using Internet search query volumes in Baidu (2017), the largest internet search engine in China, we constructed a prefectural panel data (278 prefectures, 52 weeks) and employed dynamic panel GMM system estimation to analyze the relationship between weekly concentration of PM2.5 (Mean = 87 μg·m^− 3) and the index of suicidal ideation (Mean = 49.9).

Results

The results indicate that in the spring and winter, a 10 μg·m^− 3 increase in the prior week’s PM_2.5 in a Chinese city is significantly associated with 0.020 increase in ISI in spring and a 0.007 increase in ISI in winter, after taking account other co-pollutants and meteorological conditions.

Conclusion

We innovatively proposed the measure of suicidal ideation and provided suggestive evidence of a positive association between suicidal ideation and PM_2.5 level.

Seasonal and temperature effect on serum lithium concentrations

BACKGROUND

Lithium remains the gold standard treatment for bipolar disorder. However, it has a very narrow therapeutic index (0.6-0.8 mmol/L). It has been suggested that high environmental temperature can lead to dehydration, elevated plasma lithium concentration and then lithium toxicity.

OBJECTIVES

We aimed to investigate the effect of seasonal and short-term changes in temperature on serum lithium concentrations in Sydney, Australia.

METHODS

We retrospectively analysed data from all patients who had serum lithium concentrations taken from the Prince of Wales and Sutherland Hospitals between 2008 and 2018. Temperature data came from the Bureau of Meteorology. We examined correlations between lithium concentrations and the preceding 5 days maximum temperatures, month and season. We also performed a longitudinal analysis of the effect of temperature and seasons within selected patients who had repeated levels.

RESULTS

A total of 11,912 serum lithium concentrations from 2493 patients were analysed. There was no significant association between higher lithium concentration and preceding higher temperatures (r = -0.008, p = 0.399). There was also no important seasonal or monthly variation, across all patients or in the smaller cohort with longitudinal data (n = 123, r = 0.008, 95% confidence interval: [-0.04, 0.06]).

CONCLUSION

There were no clinically important differences in serum lithium concentration related to seasons, months or temperatures, which suggests that patients on lithium are able to adequately maintain hydration during hot weather in Sydney.

Seasonal changes in suicide in South Korea, 1991 to 2015

Seasonality of suicidal behavior has been widely reported in many epidemiological studies with a well replicated suicide peak in spring followed by a trough in winter season. Research from some regions over the past few decades has shown a diminishing seasonal pattern of suicides and this introduced a new perspective on the suicide study. Data on all suicide deaths from the period 1991 to 2015 was extracted from the South Korean National Death Registration data set which was made available by Statistics Korea. Our findings confirmed a strong seasonal effect of suicides in South Korea throughout the study period and a marked diminishing pattern was observed since the period of 2006–2010. The rhythm of suicides kept changing across the time intervals with a spring peak followed by a second peak in late summer/autumn. The seasonality varied across age groups and the seasonal effect among the Korean elderly suicides was still found to be significant though a diminishing pattern was observed recently.

Seasonality in bipolar disorder: Effect of sex and age

BACKGROUND

Mood episodes in bipolar disorder (BD) are reported to exhibit a seasonal pattern (SP). However, it is unclear whether this pattern is influenced by a patient's sex and age.

METHODS

In this nationwide registry study, we examined all inpatient treatments due to a manic (F31.0-2), depressive (F31.3-5) or mixed (F31.6) BD-episode in Austria for 2001-2014. Calculations were based on directly age-standardized rates and seasonality was analyzed on a monthly basis.

RESULTS

The database comprised 60,607 admissions (35.8% men). SP were shown for women during manic (summer-autumn), depressive (winter) and mixed (summer) episodes, for men only during manic (summer) episodes. However, no significant sex differences (manic p = 0.101, depressive p = 0.295, mixed p = 0.622 episode) were found. Women at young age (15-35 years) seemed to be more vulnerable to a SP in manic and mixed episodes.

LIMITATIONS

Only aggregated patient data of inpatient treatments and no single case histories were available.

CONCLUSIONS

In this nationwide registry study, a distinct SP could be shown for manic episodes in men and women, as well as a SP for depressive and mixed episodes in women. As no significant difference in any BD-subgroup could be observed, the effect of sex on the SP seems to be small, if existing at all. However, when taking age into account, we observed a higher likelihood for a SP in young women. Single case studies with information on possible further influencing factors (e.g. medication use) might help to clarify the impact of sex and age on SP in more detail.

Seasonal variation of spontaneous blink rate and beta EEG activity

Seasonal variations of the photoperiod have been shown to regulate biological and behavioral functions, with also effects on clinical symptom and course of several psychiatric conditions. Although melatonin is considered the principal signal used to transmit informations about the light and dark cycle, a dopamine (DA) role in regulating seasonal changes has been suggested. Few studies have addressed a seasonal pattern of dopamine, and human studies have been conducted on inter-subject differences, comparing measures obtained during fall-winter with those of spring-summer. We studied within-subject seasonal changes of blink rate (BR), a indirect marker of central DA activity, in 26 normal subjects (15 females and 11 males, mean age: 24.7 ± 4.0) during winter, spring, summer and fall. Occipital EEG activity and subjective measures of vigilance and mood were also assessed to account for variations on arousal and fatigue. A significant seasonal effect was found for BR, with higher rate in summer, and for EEG beta activity, with higher activity in spring and summer. Subjective fatigue was found higher in winter. According to our data, it is possible that higher BR and increased EEG beta activity result by an arousal activation sustained by dopamine systems during the months with a long photoperiod.

Assessing Effect Modification of Excess Winter Death by Causes of Death and Individual Characteristics in Zhejiang Province, China: A Multi-Community Case-Only Analysis

Mortality in many parts of the world has a seasonal pattern, with a marked excess of deaths during winter. To date, however, there is very little published evidence on the nature of this wintertime excess in low- and middle-income countries. In this study, we aimed to quantify the extent of the death peak in winter and to assess effect modification on excess winter death (EWD) by individual characteristics and cause of deaths in China. We used a Cosinor model to examine seasonal patterns for specific causes of deaths and a case-only analysis of deaths in winter compared with other seasons to assess effect modification by individual characteristics. A total of 398,529 deaths were investigated between January 2010 and December 2013 in Zhejiang Province, China. Deaths peaked in winter, and overall mortality was around 30% higher in winter than in summer. Although diseases of the respiratory and circulatory systems were highly seasonal, surprisingly we observed that deaths from mental and behavioral disorders exhibited greater fluctuation. Males, the elderly and illiterate individuals suffered high EWD. EWDs were also particularly common in emergency rooms, at home, on the way to hospitals, and in nursing homes/family wards. This study highlighted the high EWD in some previously unreported groups, indicating new information to facilitate the targeting of necessary preventive measures to those at greatest risk in order to mitigate wintertime death burdens.

Season of treatment initiation with antidepressants and suicidal behavior: A population-based cohort study in Sweden

BACKGROUND

Decreased binding capacity of SERT in the prefrontal cortex has been observed in both suicide victims and suicide attempters. Moreover, some studies have shown that SERT has a seasonal variation with lower binding capacity in the spring and summer, which coincides with a seasonal peak of suicides. Our aim was to explore whether the season of treatment initiation with antidepressants is associated with suicide or suicide attempt and compare it with the underlying suicide seasonality in the general population.

METHODS

Using Swedish registers, patients who initiated treatment with an antidepressant were followed up to three months for suicidal behavior. Cox regression analyses were used. Results were compared with the underlying seasonal pattern by calculating standardized mortality ratios (SMRs) for suicides and standardized incidence ratios (SIRs) for suicide attempts.

RESULTS

Patients aged ≥65 years had higher risk for suicide when initiating antidepressant treatment in the summer, and also a higher risk for suicide attempt when initiating treatment in the spring and summer. Young patients (0-24 years) presented a higher risk for suicide attempt when initiating treatment in the autumn. Patients with previous suicide attempt had a seasonal pattern, with a higher risk to carry out a suicide attempt in the summer and autumn. Results from the SMR and SIR calculations numerically support these findings.

LIMITATIONS

We used information of filling an antidepressant prescription as a proxy of actual antidepressant treatment. Patients with combination, augmentation therapy or those switching antidepressant during follow-up were excluded. Thus, our results refer to less complicated psychopathology.

CONCLUSIONS

Our results indicate an interaction between biological and health care-related factors for the observed seasonal pattern of suicidal behavior in the elderly, whereas psychological and societal factors may be more important for the seasonality observed in the younger patients.

Involuntary admissions in Italy: the impact of seasonality

OBJECTIVE

The aim of this study is to assess the prevalence of involuntary admissions with regard to seasonality and clinical associated features, in a sample of patients admitted to a psychiatric unit in a period of 24 months.

METHODS

All subjects consecutively admitted to the Psychiatric Inpatient Unit of the San Luigi Gonzaga Hospital, Orbassano (University of Turin, Italy) from September 2013 to August 2015 were recruited. Socio-demographic and clinical characteristics were collected.

RESULTS

Seven hundred and thirty admissions in psychiatric ward were recognized. The prevalence of involuntary admission was 15.4%. Patients with involuntary hospitalizations showed a higher education level, a higher prevalence of admission in spring/summer with a significant peak in June, a longer duration of hospitalization and a lower suicide ideation. Among involuntary admissions, physical restraint and suicide attempts were more prevalent during spring compared to the other seasons.

CONCLUSIONS

Seasonality has an important role in the psychopathology of psychiatric disorders, particularly in bipolar and related disorder, and may represent an influencing factor in hospital admissions and hospitalizations. Seasonal pattern must be considered while managing diagnosis and treatment of mental disorders, with regard to prevention and psychoeducation of patients.

Seasonality of hospital admissions for mental disorders in Hanoi, Vietnam

BACKGROUND

Some studies have shown a relationship between seasonality in weather patterns and depressive and behavioural disorders, especially in temperate climate regions. However, there is a lack of studies describing the seasonal patterns of hospital admissions for a variety of mental disorders in tropical and subtropical nations. The aim of this study has been to examine the relationship between seasons and daily hospital admissions for mental disorders in Hanoi, Vietnam.

DESIGNS

A 5-year database (2008-2012) compiled by Hanoi Mental Hospital covering mental disorder admissions diagnosed by the International Classification of Diseases 10 was analysed. A negative binominal regression model was applied to estimate the associations between seasonality and daily hospital admissions for mental disorders, for all causes and for specific diagnoses.

RESULTS

The summer season indicated the highest relative risk (RR=1.24, confidence interval (CI)=1.1-1.39) of hospital admission for mental disorders, with a peak in these cases in June (RR=1.46, CI=1.19-1.7). Compared to other demographic groups, males and the elderly (aged over 60 years) were more sensitive to seasonal risk changes. In the summer season, the RR of hospital visits among men increased by 26% (RR=1.26, CI=1.12-1.41) and among the elderly by 23% (RR=1.23, CI=1.03-1.48). Furthermore, when temperatures including minimum, mean, and maximum increased 1°C, the number of cases for mental disorders increased by 1.7%, 2%, and 2.1%, respectively.

CONCLUSION

The study results showed a correlation between hospital admission for mental disorders and season.

Seasonality of suicide behavior in Northwest Alaska: 1990-2009

OBJECTIVES

Suicide is a leading cause of death worldwide, and disproportionately affects Indigenous populations. Seasonal suicide patterns are variable in the literature, and could offer novel approaches to the timing and focus of prevention efforts if better understood. With a suicide surveillance system in place since 1989, this study offers an unprecedented opportunity to explore seasonal variations in both fatal and non-fatal suicide behavior in an Indigenous Arctic region.

STUDY DESIGN

Cross-sectional.

METHODS

In this descriptive study, we analyzed data collected from 1990 to 2009 in the rural northwest region of Alaska, both graphically and using the chi-squared test for multinomials.

RESULTS

We found a significant monthly variation for suicide attempts, with a peak in suicide behavior observed between April and August (P = 0.0002). Monthly variation was more pronounced among individuals ≤29 years of age, and was present in both males and females, although the seasonal pattern differed by sex.

CONCLUSIONS

Our findings of a significant seasonal pattern in suicide behavior, with monthly variation (summer peak) in non-fatal suicide behavior among younger age groups, and among both males and females can assist planners in targeting subpopulations for prevention at different times of the year.

Depression-related treatment and costs in Germany: Do they change with comorbidity? A claims data analysis

BACKGROUND

Existing diverse bottom-up estimations of direct costs associated with depression in Germany motivated a detailed patient-level analysis of depression-related treatment (DRT), -costs (DRC) and Comorbidity.

METHODS

A large sickness fund's claims data was used to retrospectively identify patients aged 18-65 years with new-onset depression treatment between January 1st and February 15th 2010, and follow them until December 31st 2010, describe DRT, estimate associated DRC, and predict DRC with a generalised linear model.

RESULTS

A total of 18,139 patients were analysed. Mean direct DRC were €783. Predictors of DRC regarding psychiatric comorbidities were: "Delusion, psychotic disorders and personality disorders" (DRC-ratio 1.72), "Alcohol/drug addiction" (1.82), "abuse of alcohol/drugs" (1.57). Predictors of DRC regarding medical comorbidities were: "Rheumatoid arthritis" (0.77), "atherosclerosis" (0.65), "pregnancy" (0.66), and "Osteoarthritis" (1.87). Of all patients, 60.8% received their most intense/specialised DRT from a general practitioner, a medical specialist (23.7%), a psychotherapist (8.0%), a medical specialist and psychotherapist (2.9%), or in hospital (4.6%). Serious psychiatric comorbidity nearly tripled depression-related hospitalisation rates.

LIMITATIONS

Seasonal affective disorder and missing psychiatric outpatient clinic data must be considered.

CONCLUSIONS

Estimated DRC are significantly below the assessment of the German national guideline. Differing definitions of observation period and cost attribution might explain differing German DRC results. Signs of hospital psychiatric comorbidity bias indicate overestimation of hospital DRC. Identified associations of DRC with certain medical diseases in older adults warrant further research. Up to one quarter of patients with severe depression diagnosis might lack specialist treatment.

Psychiatric hospitalizations for affective disorders in Warsaw, Poland: Effect of season and intensity of sunlight

The purpose of this study was to assess any associations between the number of hospitalizations for affective disorders, seasons of the year and the intensity of sunlight in Poland, a country with a very changeable climate and significant seasonal fluctuations. We analyzed 2837 admissions with affective disorders hospitalized in the Institute of Psychiatry and Neurology in Warsaw, between 2002 and 2010 (mania, n=380, mixed episode, n=131, bipolar depression, n=736, recurrent depression, n=681, single depressive episode, n=909). For each diagnostic group admission time series were created and categorized into subgroups according to sex and age, and these were analyzed by means of the Autoregressive Integrated Moving Average (ARIMA) method. Regression models and correlations were used to assess the influence of the intensity of sunlight on the number of hospitalizations. Most mania admissions were noted in spring/summer months and in midwinter, mixed episode-late spring and winter, and depression (bipolar, recurrent and single depressive episode)-spring and autumn months. The association between frequency of admissions and monthly hours of sunshine was observed in some age and sex subgroups of patients with bipolar disorder and single depressive episode. The results support the seasonality of admissions of patients with affective disorders.

Analyzing Seasonal Variations in Suicide With Fourier Poisson Time-Series Regression: A Registry-Based Study From Norway, 1969-2007

Seasonal variation in the number of suicides has long been acknowledged. It has been suggested that this seasonality has declined in recent years, but studies have generally used statistical methods incapable of confirming this. We examined all suicides occurring in Norway during 1969-2007 (more than 20,000 suicides in total) to establish whether seasonality decreased over time. Fitting of additive Fourier Poisson time-series regression models allowed for formal testing of a possible linear decrease in seasonality, or a reduction at a specific point in time, while adjusting for a possible smooth nonlinear long-term change without having to categorize time into discrete yearly units. The models were compared using Akaike's Information Criterion and analysis of variance. A model with a seasonal pattern was significantly superior to a model without one. There was a reduction in seasonality during the period. Both the model assuming a linear decrease in seasonality and the model assuming a change at a specific point in time were both superior to a model assuming constant seasonality, thus confirming by formal statistical testing that the magnitude of the seasonality in suicides has diminished. The additive Fourier Poisson time-series regression model would also be useful for studying other temporal phenomena with seasonal components.

Photoperiodic and circadian bifurcation theories of depression and mania

Seasonal effects on mood have been observed throughout much of human history.  Seasonal changes in animals and plants are largely mediated through the changing photoperiod (i.e., the photophase or duration of daylight).  We review that in mammals, daylight specifically regulates SCN (suprachiasmatic nucleus) circadian organization and its control of melatonin secretion.  The timing of melatonin secretion interacts with gene transcription in the pituitary pars tuberalis to modulate production of TSH (thyrotropin), hypothalamic T3 (triiodothyronine), and tuberalin peptides which modulate pituitary production of regulatory gonadotropins and other hormones.  Pituitary hormones largely mediate seasonal physiologic and behavioral variations.  As a result of long winter nights or inadequate illumination, we propose that delayed morning offset of nocturnal melatonin secretion, suppressing pars tuberalis function, could be the main cause for winter depression and even cause depressions at other times of year.  Irregularities of circadian sleep timing and thyroid homeostasis contribute to depression.  Bright light and sleep restriction are antidepressant and conversely, sometimes trigger mania.  We propose that internal desynchronization or bifurcation of SCN circadian rhythms may underlie rapid-cycling manic-depressive disorders and perhaps most mania.  Much further research will be needed to add substance to these theories.

Alterations in circadian/seasonal rhythms and vegetative functions are related to suicidality in DSM-5 PTSD

BACKGROUND

Alterations in rhythmicity and vegetative functions have been reported as correlates of suicidality, particularly in patients with mood disorders. No investigation has addressed their impact on patients with post-traumatic stress disorder (PTSD). Aim of the present study was to fulfill this gap.

METHODS

Sixty-five out- and inpatients with DSM-5 PTSD were assessed by using the Mood Spectrum-Self Report-Lifetime Version (MOODS-SR), a questionnaire for lifetime mood spectrum symptomatology including alterations in circadian/seasonal rhythms and vegetative functions. Six items of the MOODS-SR were combined and dichotomized to assess suicidal ideation and/or attempts.

RESULTS

Significant and positive associations were found between symptoms of lifetime dysregulations in rhythmicity and vegetative functions and suicidal ideation and/or attempts. All MOODS-SR sub-domains (rhythmicity, sleep, appetite/weight, sexual function, physical symptoms) were associated with an increased likelihood of suicidal ideation, but only changes in appetite/weight were associated with greater odd ratios of suicide attempts (OR = 2.099, 95% CI 1.148-3.841).

CONCLUSIONS

Our results suggest that lifetime dysregulations in rhythmicity and vegetative functions may represent correlates of suicidality in patients with DSM-5 PTSD.

Daily weather variables and affective disorder admissions to psychiatric hospitals

Numerous studies have reported that admission rates in patients with affective disorders are subject to seasonal variation. Notwithstanding, there has been limited evaluation of the degree to which changeable daily meteorological patterns influence affective disorder admission rates. A handful of small studies have alluded to a potential link between psychiatric admission rates and meteorological variables such as environmental temperature (heat waves in particular), wind direction and sunshine. We used the Kruskal-Wallis test, ARIMA and time-series regression analyses to examine whether daily meteorological variables--namely wind speed and direction, barometric pressure, rainfall, hours of sunshine, sunlight radiation and temperature--influence admission rates for mania and depression across 12 regions in Ireland over a 31-year period. Although we found some very weak but interesting trends for barometric pressure in relation to mania admissions, daily meteorological patterns did not appear to affect hospital admissions overall for mania or depression. Our results do not support the small number of papers to date that suggest a link between daily meteorological variables and affective disorder admissions. Further study is needed.

Seasonality and bipolar disorder: a systematic review, from admission rates to seasonality of symptoms

INTRODUCTION

Bipolar disorder (BD) is a severe mental disorder affecting 1-4% of the population worldwide. It is characterized by periods of (hypo)manic and depressive episodes. Seasonal patterns (SP) may be observed in admission rates, mood relapses and symptom fluctuations.

METHODS

We conducted a systematic review of seasonality in BD, classifying studies based on seasonal admission rates to seasonality of symptoms assessments.

RESULTS

Fifty-one papers were identified of which 32 addressed hospitalization rates by season, 6 addressed categorical diagnoses, and 13 explored symptom dimensions. Seasonal peaks for different BD mood episodes are observed worldwide and widely replicated. Manic episodes peak during spring/summer and, to a lesser extent, in autumn, depressive episodes peak in early winter and, to a lesser extent, summer, and mixed episodes peak in early spring or mid/late summer. There was a high frequency of SP for manic episodes (15%) and depressive episodes (25%), the latter being associated with a more complex clinical profile (BD II subtype, comorbid eating disorders, more relapses and rapid cycling). Finally, there was evidence for greater seasonal fluctuations in mood and behavior in individuals with BD than in those with unipolar depression or 'healthy' controls.

LIMITATIONS

Sample size, gender distribution, methodological quality and sophistication of the analytical approaches employed varied considerably.

CONCLUSIONS

There is evidence of seasonality in BD, with emerging evidence that climatic conditions may trigger BD symptoms or episodes. A better understanding of the underlying mechanisms would facilitate the development of personalized chronobiological therapeutic and preventive strategies.

Bipolar disorder with seasonal pattern: clinical characteristics and gender influences

Bipolar disorder (BD) has a multifactorial etiology with heterogeneous clinical presentations. Around 25% of BD patients may present with a depressive seasonal pattern (SP). However, there are limited scientific data on the prevalence of SP, its clinical manifestations, and any gender influence. Four hundred and fifty-two BD I and II cases (62% female), recruited from three French university-affiliated psychiatric departments, were assessed for SP. Clinical, treatment, and sociodemographic variables were obtained from structured interviews. One hundred and two (23%) cases met DSM-IV (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition) criteria for SP, with similar frequency according to gender. Multivariate analysis showed a significant association between SP and BD II (odds ratio [OR] = 1.99, p = 0.01), lifetime history of rapid cycling (OR = 2.05, p = 0.02), eating disorders (OR = 2.94, p = 0.003), and total number of depressive episodes (OR = 1.13, p = 0.002). Seventy-one percent of cases were correctly classified by this analysis. However, when stratifying the analyses by gender, SP was associated with BD II subtype (OR = 2.89, p = 0.017) and total number of depressive episodes (OR = 1.21, p = 0.0018) in males but with rapid cycling (OR = 3.02, p = 0.0027) and eating disorders (OR = 2.60, p = 0.016) in females. This is the first study to identify different associations between SP and clinical characteristics of BD according to gender. The authors suggest that SP represents a potentially important specifier of BD. These findings indicate that seasonality may reflect increased severity or complexity of disorder.

Evidence for seasonal mania: a review

OBJECTIVE

The goal of this article is to summarize the evidence for seasonal mania based on research studies and findings concerning interrelationships among circadian rhythm, manic episodes, and mood stabilizers.

METHODS

The PubMed database was searched using the key word "seasonal mania." This search generated a list of 197 papers published between 1990 and 2011, 29 of which were original research studies on seasonal mania. The findings from these studies were reviewed with regard to their relevance to the mechanisms involved in seasonal mania and strategies for managing mania.

RESULTS

Of the 29 research studies, the majority (n=23) provided evidence for a significant seasonal pattern for mania, while the other 6 studies did not. Most of the studies reported that mania occurred more often during spring and summer and that depression occurred more often during fall and winter. The authors of the studies estimated a prevalence of seasonal mania of 15% among patients with bipolar disorder. It is hypothesized that the underlying mechanism for seasonal mania may be hypersensitivity to bright light that suppresses melatonin production. Both lithium and valproate can counteract the action of bright light in suppressing melatonin and prolong sleep-wake cycles in the circadian rhythms of patients with bipolar disorder. These effects may at least partially explain their efficacy as mood stabilizing agents. No research studies were located that provided information on managing the medication regimen, especially of mood stabilizing medications, based on the seasonal patterns seen in some patients with bipolar disorder in order to reduce the risk of relapse associated with seasonal mania. Positive findings in this area might lead to a new paradigm for the management of patients with bipolar disorder who have seasonal mania.

Seasonal variation of manic and depressive symptoms in bipolar disorder

OBJECTIVES

Analyses of seasonal variation of manic and depressive symptoms in bipolar disorder in retrospective studies examining admission data have yielded conflicting results. We examined seasonal variation of mood symptoms in a prospective cohort with long-term follow-up: the Collaborative Depression Study (CDS).

METHODS

The CDS included participants from five academic centers with a prospective diagnosis of bipolar I or II disorder. The sample was limited to those who were followed for at least 10 years of annual or semi-annual assessments. Time series analyses and autoregressive integrated moving average (ARIMA) models were used to assess seasonal patterns of manic and depressive symptoms.

RESULTS

A total of 314 individuals were analyzed (bipolar I disorder, n = 202; bipolar II disorder, n = 112), with both disorders exhibiting the lowest frequency of depressive symptoms in summer and the highest around the winter solstice, though the winter peak in symptoms was statistically significant only with bipolar I disorder. Variation of manic symptoms was more pronounced in bipolar II disorder, with a significant peak in hypomanic symptomatology in the months surrounding the fall equinox.

CONCLUSIONS

Significant seasonal variation exists in bipolar disorder, with manic/hypomanic symptoms peaking around the fall equinox and depressive symptoms peaking in the months surrounding the winter solstice in bipolar I disorder.

Seasonal influences on admissions for mood disorders and schizophrenia in a teaching psychiatric hospital in Egypt

BACKGROUND

Distinct seasonal variation in hospital admission and various associations with the climatic parameters for mood disorders and schizophrenia have been previously reported in several world regions. There are, however, no North-African studies on this association.

METHODS

The charts of 1987 patients with mood disorders (mania 1181, depression 806) and 1359 patients with schizophrenia admitted from 2003 to 2007 from an university hospital at Mansoura, Egypt, were reviewed. Seasonality was assessed with Cosinor Analysis. Correlations of the rate of admissions for affective disorders and schizophrenia to climatic variables were performed, including lagged and differenced data.

RESULTS

There was a significant seasonal variation in the monthly admission frequencies both for mania (peak in June) and for depression (peak in December) but no significant seasonal variation was found in admissions with diagnosis of schizophrenia. The number of admissions for mania was positively correlated to indicators of temperature and luminosity, but inversely correlated to relative humidity. Quite the opposite, the number of admissions for depression showed a negative correlation to temperature and luminosity, but a positive correlation to relative humidity. 55-57% of the monthly variance of the number of admissions for mood disorders was explained by climatic variables.

CONCLUSIONS

Seasonality of admissions for mood disorders, but not for schizophrenia, has been demonstrated, in an African Mediterranean region with a fairly constant climate. The association between admission rates and climatic variables found in this study could pave the way for further studies aiming at exploration of the biological mechanism of this association as well as tailoring of treatment interventions on mood disorders.

Do symptoms of bipolar disorder exhibit seasonal variation? A multisite prospective investigation

OBJECTIVES

Evidence that symptoms of bipolar disorder (BD) vary seasonally is inconclusive. Here, a multisite prospective investigation of patients with BD was used to test the hypothesis that, on average, depressive symptoms peak in autumn/winter and hypo/manic symptoms peak in spring/summer. Secondary analyses explored gender and diagnosis [bipolar I disorder (BD-I) versus bipolar II disorder (BD-II)] effects on seasonality.

METHODS

A sample of 429 patients with BD (61.6% female; 56.2% BD-I) were recruited from 12 sites across Canada. Clinician-rated measures of manic [Young Mania Rating Scale (YMRS), n = 4,753 total observations] and depression symptoms [Montgomery-Åsberg Depression Rating Scale (MADRS), n = 4,691 observations] were taken at scheduled three-month visits as well as any unscheduled visits. At scheduled visits only, Hamilton Depression Rating Scale (Ham-D) assessments (n = 3,153 observations) were also made. Multi-level modeling (MLM) analyses were conducted separately for the three dependent variables and three definitions of Time: calendar month, nominal season, and harmonic analysis.

RESULTS

Primary analyses of the whole sample found that for manic symptoms (YMRS), neither calendar month nor nominal season were significant, and harmonic analyses found an unpredicted frequency two sinusoid, with peaks at 4th December and 4th June (p < 0.018). Secondary analyses found that this sinusoid approximately fit the YMRS data for females and those diagnosed with BD-II. For depression symptoms measured on the MADRS and Ham-D, no significant seasonal patterns were found in primary analyses of the whole sample. Secondary analyses found a significant increase in MADRS scores in November/December among females, but this pattern was not corroborated in nominal season or harmonic analyses.

CONCLUSIONS

No evidence of systematic seasonal variation in symptoms was found in the sample as a whole. Primary analyses found no evidence that hypo/manic symptoms peaked in the lighter months and depressive symptoms peaked in the darker months. The present findings align with broadly negative conclusions from three earlier prospective investigations, and provide the strongest evidence to date that seasonal changes do not in fact cause coordinated variation in BD symptoms.

Seasonality of Chinese rural young suicide and its correlates

BACKGROUND

There had been few studies on seasonality of Chinese suicide especially for Chinese rural youths. In this research, we wanted to find the seasonal pattern and the relationship between personal and behavioral characteristics and seasonal variation of suicide.

METHOD

We examined Chinese rural young adults aged 15 to 34 years who died by suicide using Psychological Autopsy method to gather information from the informants of suicide victims. Altogether 330 suicide victims were collected among which 144 were female and 186 were male. The χ(2) test was used for comparison, and the multiple logistic regressions and Odds Ratios were adopted to analyze the seasonal preferences of suicide victims.

RESULT

Seasonal summer peak of suicide emerged in total population and in each subgroup. Four logistic regression models were constructed: in spring, six variables were included in the regression model, which were Gender (OR = 1.627), Pesticide Used (OR = 1.622), Life Events (OR = 2.764), Suicide Intent (OR = 1.641), Marital Status (OR = 0.574) and Family Conflicts (OR = 0.590); in summer, only Marital Status (OR = 1.927) was accepted; in autumn, four variables including Marital Problems (OR = 1.924), Trait Anxiety (OR = 1.758), Gender (OR = 0.518) and Religion (OR = 0.534) were retained; in winter, Pesticide Used (OR = 0.486) and Suicide Intent (OR = 0.614) were retained.

CONCLUSION

Seasonal variations of personal and behavioral characteristics, combined with social activities, might also play very important roles in suicide seasonality.

Evolutionary origin of bipolar disorder-revised: EOBD-R

The hypothesis of the evolutionary origin of bipolar disorder (EOBD) synthesized ideas about the biological clock and seasonal shifts in mood (Rosenthal, Wehr) with theorizing that bipolar disorder descends from a pyknic (compact, cold-adapted) group (Kretchmer). The hypothesis suggested that bipolar behaviors evolved in the northern temperate zone as highly derived adaptations to the selective pressures of severe climatic conditions during the Pleistocene. Given evidence of Neandertal contributions to the human genome, the hypothesis is extended (EOBD-R) to suggest Neandertal as the ancestral source for bipolar vulnerability genes (susceptibility alleles). The EOBD-R hypothesis explains and integrates existing observations: bipolar disorder has the epidemiology of an adaptation; it is correlated with a cold-adapted build, and its moods vary according to light and season. Since the hypothesis was first published, data consistent with it have continued to appear. Individuals with seasonal affective disorder, which is related to bipolar disorder, have been shown to manifest a biological signal of season change similar to that found in hibernating animals. The involvement of the circadian gene network in the pathophysiology of bipolar disorder has been confirmed. Because selective pressures during the Pleistocene would have been greatest for women of reproductive age, they are expected to manifest winter depression more than males or younger females, which is the case. (This sex difference is also found in hibernating mammals.) Because it is hypothesized that the evolution of bipolar disorder took place in the northern temperate zone during the Pleistocene, it is not expected that individuals of African descent, lacking Neandertal genes, will manifest circular bipolar I disorder, and in fact, the incidence of bipolar disorder among black individuals is less than among whites. A definitive test of the hypothesis is proposed: It is predicted that the bipolar and Neandertal genomes will be more similar than the modern human and Neandertal genomes, and the modern human and San and Yoruba genomes will be more similar than the bipolar and San and Yoruba genomes. Failure to confirm these predictions will falsify the EOBD-R hypothesis. The EOBD-R hypothesis has important implications in the search for bipolar vulnerability genes and our understanding of ourselves and our Neandertal ancestor. At a practical level, confirmation of the EOBD-R hypothesis will boost interest and research in the prevention and management of bipolar symptoms by manipulation of ambient light.

The role of environmental influences on schizophrenia admissions in Israel

OBJECTIVE

The role of environmental factors in hospitalization of patients with schizophrenia is incompletely understood. This study attempts to relate the pattern of hospital admissions to environmental variables such as season and to social factors such as nationally celebrated holidays.

METHODS

Charts of all adults (n = 4,331) with a discharge diagnosis of schizophrenia admitted to the Abarbanel Mental Health Centre (Bat Yam, Israel) between 1 January 2001 and 31 December 2005 were reviewed. Hospitalizations were classified by gender, first or repeat admission, month and season of admission, and whether or not the admission coincided with a major Jewish holiday period.

RESULTS

There was a significant reduction (p < 0.05) in first admissions for men during April, the month corresponding to Passover, the most widely celebrated holiday in Israel. This pattern was not seen for women or for repeat admissions. There was no significant effect of the season upon admission rates, using two different methods of defining the season.

CONCLUSIONS

This study demonstrated significant monthly variability in admission rates and a possible protective effect of a widely celebrated public religious holiday. A consistent effect of season upon rates of admission was not found. Future studies need to identify which specific social factors exert a protective or harmful effect and study how knowledge of these effects can be translated into clinical practice.

Does the weather make us sad? Meteorological determinants of mood and depression in the general population

It is a common and well-spread belief that people feel more depressed when the weather is bad. However, whether meteorological factors such as temperature, sunshine and rainfall can actually account for variations in the prevalence of depression in the general population has yet to be investigated. We aimed to assess the influence of weather conditions on the seasonal variation of depression observed in the general population. We used data from a large-scale depression-screening programme in the south of the Netherlands. Seasonal prevalence of DSM-IV classified major depression and sad mood in a sample of 14,478 participants from the general population was calculated, and linked to mean daily temperature, duration of sunshine and duration of rainfall in logistic regression analyses. The prevalence of major depression and sad mood showed seasonal variation, with peaks in the summer and fall. Weather conditions were not associated with mood, and did not explain the seasonal variation we found. We conclude that, contrary to popular belief, weather conditions and sad mood or depression do not seem to be associated. Future studies might use daily measures of well-being as outcome.

Further evidence of seasonality of mania in the tropics

BACKGROUND

Findings from various temperate regions have quite consistently shown a spring/summer peak for the occurrence of manic episodes, but inconsistencies can still be found in results from tropical regions. The present study was designed to investigate the seasonal distribution of mania and its correlations to climatic variables, in a large sample of patients visiting the emergency psychiatric room.

METHODS

A hospital registry of 5172 emergency psychiatric visits for mania, 2000-2007, at a public psychiatric hospital at Belo Horizonte, Brazil (latitude 19 degrees 55' S), was analyzed. Seasonality was assessed with Cosinor Analysis. Correlations of the rate of admissions for mania to climatic variables were performed, including lagged and differenced data.

RESULTS

A minor, but significant seasonal pattern was evidenced, with a late winter/spring peak and the nadir in February (late summer). The regression model including secular and seasonal components explained 44.4% of the variance of visits for mania. The rate of emergency visits for mania was negatively correlated to relative humidity and rainfall. Altogether, climatic variables explained 8.1% of the variance in the rate of emergency visits for mania.

LIMITATIONS

Using hospital registry data may have led to misclassification of diagnosis. The ecologic design does not account for seasonal evolution of individual cases.

CONCLUSION

Emergency psychiatric visits for mania were more frequent in late winter/spring, corresponding to the drier seasons of Belo Horizonte. Seasonality of mania in the tropics was corroborated by these results.

Seasonality in suicide--a review and search of new concepts for explaining the heterogeneous phenomena

Seasonality is one of the oldest and most resistant-to-elucidation issues in suicide research. However, in recent years epidemiological research has yielded new results, which provide new perspectives on the matter. This qualitative review summarizes research published since the 1990 s. In particular, the focus is on studies dealing with the historical change of seasonality, cross-sectional comparisons including method-specific diversity, and the association with weather variables and other putative covariates. Recent research has shown that in Western countries the seasonality of suicide is tending to diminish and may, eventually, disappear. It can no longer be considered a universal and homogeneous phenomenon. In addition, different major seasonal cycles have now been determined which mainly depend on different suicide methods. Just as in the epidemiology of suicide methods, the (seasonal) availability and perceived adequacy of methods emerge as the major driving force beyond the seasonal phenomena in suicide.

Gender differences in antidepressant use-related seasonality change in suicide mortality in Hungary, 1998-2006

OBJECTIVES

Studies show that the seasonality of suicide (spring/early summer peak, winter low) is mainly the consequence of the seasonal incidence of depression-related suicides. The aim of the present study was to analyse the relationship between increasing antidepressant utilization and national suicide rate of Hungary between 1998 and 2006, with particular regard to seasonal patterns and gender differences.

METHODS

Time trend analysis (ARIMA) had been applied to investigate the correlation between the trend of antidepressant prescription and both of suicide rates and seasonality index.

RESULTS

During the 9 years of the study period there was a significant (P<0.001) correlation between the steadily increasing antidepressant prescription (113%) and continuous decline in total national suicide rate (23%) as well as both in females and males (21 and 23%, respectively), but this relationship was 8-fold stronger in males. Increasing antidepressant utilization was associated with significantly decreased seasonality of suicides only among males.

CONCLUSIONS

The results suggest that decreasing seasonality of suicides could be a good marker of lowering rate of depression-related suicides in the population particularly among males.

Seasonal spring peaks of suicide in victims with and without prior history of hospitalization for mood disorders

BACKGROUND

Seasonal spring peaks of suicide are highly replicated, but their origin is poorly understood. As the peak of suicide in spring could be a consequence of decompensation of mood disorders in spring, we hypothesized that prior history of mood disorders is predictively associated with suicide in spring.

METHODS

We analyzed the monthly rates of suicide based upon all 37,987 suicide cases in the Danish Cause of Death Registry from 1970 to 2001. History of mood disorder was obtained from the Danish Psychiatric Central Register and socioeconomical data from the Integrated Database for Labour Market Research. The monthly rate ratio of suicide relative to December was estimated using a Poisson regression. Seasonality of suicide between individuals with versus without hospitalization for mood disorders was compared using conditional logistic regression analyses with adjustment for income, marital status, place of residence, and method of suicide.

RESULTS

A statistically significant spring peak in suicide was observed in both groups. A history of mood disorders was associated with an increased risk of suicide in spring (for males: RR=1.18, 95% CI 1.07-1.31; for females: RR=1.20, 95% CI 1.10-1.32).

LIMITATIONS

History of axis II disorders was not analyzed. Danish socioeconomical realities have only limited generalizability.

CONCLUSIONS

The results support the need to further investigate if exacerbation of mood disorders in spring triggers seasonal peaks of suicide. Identifying triggers for seasonal spring peaks in suicide may lead to uncovering novel risk factors and therapeutic targets for suicide prevention.

Seasonality of suicide in Sweden: relationship with psychiatric disorder

BACKGROUND

Little is known as to whether suicide seasonality is related to psychiatric disorders affecting suicide risk/incidence. The present study aims to assess suicide seasonality patterns with regard to the history of psychiatric morbidity among suicide victims.

METHODS

The history of psychiatric inpatient diagnoses in the five years prior to suicide was identified among all suicides in Sweden from 1992 to 2003. Suicide seasonality was estimated as the relative risk of suicide during the month of highest to that in the month of lowest suicide incidence. Analyses were performed with respect to sex, suicide method and history of inpatient treatment of psychiatric disorder.

RESULTS

Among both male (n=9,902) and female (n=4,128) suicide victims, there were peaks in suicide incidence in the spring/early summer. This seasonal variation was more evident in suicide victims with a psychiatric inpatient diagnosis than in those without such a diagnosis. A seasonal variation was found in most diagnostic groups, with significant peaks in males with a history of depression and in females with a history of a neurotic, stress-related, or somatoform disorder. Overall, suicide seasonality was more evident in violent than in non-violent suicide methods.

LIMITATION

Only psychiatric disorders severe enough to require hospital admission were studied.

CONCLUSION

A history of inpatient-treated psychiatric disorder appears to be associated with an increase in suicide seasonality, especially in violent suicide methods. This increase is found in several psychiatric disorders.

Accentuation of suicides but not homicides with rising latitudes of Greenland in the sunny months

BACKGROUND

Seasonal variation in suicides has been shown in many countries. We assessed the seasonality and the variation with latitude in suicides and homicides, and the impact of alcohol on the seasonality in suicides.

METHODS

Official computerized registers on causes of death in all Greenland during 1968-2002 were used. Sales data on beer from one of the major food store chains for July 2005-June 2006 were examined. Seasonal variation was assessed by Rayleigh's test for circular distributions.

RESULTS

There were a total of 1351 suicides and 308 homicides. The suicides rate varied from 4.2/100 000 person-years in 1971 to 128.4/100 000 person-years in 1987. The homicide rate varied from 2.1/100000 person-years in 1969-1970 to 34.8/100 000 person-years in 1988. Out of the 1351 suicides, 80.5% were committed by men and 19.5% by women. Median age was 25 years (n = 1351; Range 11-84 years). Violent methods of suicide were used in 95% of all cases (n = 1286). Out of the 308 homicide victims, 61% were men and 39% were women, and 13% were killed in multiple homicide events.There was a significant seasonal variation with peaks in June and troughs in the winter in all suicide cases (n = 1351, r = 0.07; Z = 7.58, p < 0.001), in violent suicides (n = 1286; r = 0.07; Z = 6.97; p < 0,001), in suicides in men (n = 1087; r = 0.07; Z = 5.39; p < 0.002) , and in women (n = 264; r = 0.10; Z = 2.36; p < 0.05), but not in homicides nor in consumption of beer. There was a bi-phasic seasonal variation in suicide victims where an alcohol-related condition was included in the death certificate. Suicides were more concentrated in the summer months north of the Arctic Circle (n = 577, r = 0.09, Z = 4.45, p < 0.01) than south of it (n = 769, r = 0.07, Z = 3.76, p < 0.002) and most concentrated in North Greenland (n = 33; r = 0.35; Z = 4.11; p < 0.01), where 48% of suicides occurred during the period of constant light. When including astronomical twilight in the constant light period 82% occurred during this time.

CONCLUSION

There was a concentration of suicides but not homicides in the summer months in all Greenland. The concentration was most pronounced at high latitudes.

Seasonality of suicide: relationship with the reason for suicide

AIMS

This study set out to test the hypothesis that the suicides that can be attributed to a psychiatric illness show a higher seasonality than the suicides due to any other reason.

METHODS

All the suicides registered in Italy from 1984 to 2000 (57,796 deaths by suicide: males = 41,741, yearly rate = 11.3 per 100,000; females = 16,055, yearly rate = 4.0 per 100,000) were analyzed with circular statistic techniques, based on the maximization of mean vector length method and on the Rayleigh test.

RESULTS

The suicides clearly attributed to a psychiatric illness were 35.0% among males and 51.3% among females. An economic reason for suicide was more frequently found among males; somatic illness or sentimental reasons were equally distributed in both sexes. The suicides attributable to a psychiatric illness showed a significantly higher seasonal unevenness than the suicides attributable to somatic illness and to sentimental or economic reasons.

CONCLUSIONS

The main drawback of this study is that psychiatric diagnoses were not formally assessed by a forensic specialist. However, it succeeded in showing that the dynamics of suicidal behaviour are not unilineal: suicides due to psychiatric or somatic illness mainly happen in spring/summer and those due to economic difficulties mainly in December. Patients with psychiatric and/or somatic illness should be more carefully followed in spring/summer.

Monthly variation in prevalence rates of comorbid depression and anxiety in the general population at 63-65 degrees North: the HUNT study

BACKGROUND

To investigate monthly variation in depression, anxiety and their comorbidity (COM) in an epidemiologic study and their association to monthly variation in suicide rates.

METHODS

60,995 participants of the Health Study of Nord-Trøndelag County in 1995-97 rated themselves on the Hospital Anxiety and Depression Scale (HADS) in all months except July. All 10,670 male and 3833 female suicides in Norway from 1969 through 1996 were included.

RESULTS

The prevalence of comorbid anxiety and depression was highest in spring (April, May) and in October (p<0.01). There was a correlation between the monthly variation in the national suicide rate and monthly variation in comorbid anxiety and depression (r=0.72, df=11, p=0.01) and for male alone (r=0.67, df=11, p=0.03). There was also a significant monthly variation in the prevalence of depression (p<0.001) and no monthly variation in the prevalence of anxiety.

LIMITATIONS

Limited information about the third of the population who did not take part in the HUNT-2 Study. HADS based depression and anxiety cover psychological symptoms, not somatic and social ones. In relation to DSM-IV and ICD-10 defined anxiety disorders and depressions, the sensitivity and specificity of HADS caseness, give a considerable number of false-positive cases.

CONCLUSIONS

Increased prevalence of comorbid depression and anxiety in males during spring, and its association with suicidality should have clinical importance, as identification and treatment could influence suicide rates.

The impact of environmental temperature on lithium serum levels

OBJECTIVES

Three studies have reported a seasonal variation in lithium serum levels, with higher levels during summer. Our objective was to investigate the impact of actual environmental temperature on lithium serum levels.

METHODS

A retrospective study was conducted using available records of lithium serum levels for the period between January 1995 and July 2004, obtained from three large teaching hospitals in The Netherlands. Lithium serum levels were linked to season and average daily temperature data obtained from the Royal Netherlands Meteorological Institute. An analysis was performed on all lithium serum levels not accounting for the intra-individual dependency of lithium serum levels. The association between season, temperature and both absolute lithium serum level and the frequency of potentially toxic serum levels was investigated. A mixed model analysis, accounting for intra-individual dependency of lithium serum levels, was performed.

RESULTS

A total of 41,102 lithium serum levels (3,054 patients) were included. A significant difference in mean lithium serum levels across seasons (p < 0.001) and temperature categories (p = 0.001) was found, peaking in summer [0.761 mmol/L, +/- standard error of the mean (SEM) 0.002] and at temperatures of 15-20 degrees C [0.762 mmol/L (+/- SEM 0.005)], and at a minimum in winter [0.748 mmol/L (+/- SEM 0.002)] and at <0 degrees C [0.741 mmol/L (+/- SEM 0.005)]. The relative frequency of potentially toxic serum levels significantly differed between seasons (p = 0.023, highest in winter), but not between temperature categories (p = 0.481). A significant positive association for intra-individual lithium serum level and season (p < 0.001) and temperature (p < 0.001) was established.

CONCLUSIONS

Season and environmental temperature have a statistically significant but therapeutically irrelevant effect on lithium serum levels.

Seasonal pattern of psychiatry service utilization in a tertiary care hospital

BACKGROUND

Seasonal and monthly variations in utilization of psychiatric services have been inadequately studied in India.

AIMS

This study sought to determine the pattern of psychiatric services utilization by patients with four broad categories of diagnosis (mood disorders (F30-39): neurotic stress-related and somatoform disorders (F40-48), schizophrenia, schizotypal and delusional disorders (F20-29) and mental and behavioral disorders due to psychoactive substance use (F10-19) in different seasons and months of the last six years.

MATERIALS AND METHODS

We conducted a teaching hospital data-based study of new patients diagnosed with psychiatric illness in the department of psychiatry, Government Medical College and Hospital, Chandigarh. Four diagnostic groups consisting of 12058 psychiatric patients who had been diagnosed and treated in the department of psychiatry of this institute from 1999-2004 were included in this evaluation. Bed occupancy rate (BOR), average length of stay (ALOS) of inpatients and seasonal index were determined. Information about weather variables (mean daily temperature, mean rainfall) was collected from the meterological department of Chandigarh.

RESULTS

Psychiatric services were utilized by 31.1% of patients with mood disorders in the summer and by 34.23% of patients with neurotic, stress-related and somatoform disorders in the autumn. Statistical analysis revealed significant difference in new cases of these two groups of disorders in different seasons.

CONCLUSION

Our study showed a significant relationship between utilization of psychiatric patients especially with mood disorders and neurotic, stress related and somatoform disorders with season (summer and autumn respectively).

Seasonal variations in bipolar disorder admissions and the association with climate: a population-based study

OBJECTIVE

Although seasonal influences on bipolar disorder admissions have long been observed, the issues of seasonality on different subtypes of mood episodes and the effects of associated climatic parameters remain controversial. This study sets out to examine seasonal variations in bipolar disorder admissions and the association with climate in Taiwan, a subtropical area with fairly constant weather conditions.

METHODS

This retrospective population-based study uses the Taiwan National Health Insurance Research Database for 1999-2003, identifying 15,060 admissions for bipolar disorder, comprising of 8631 manic, 2078 depressive and 4351 mixed/unspecified episodes. The auto-regressive integrated moving average model was applied to examine the presence of seasonality and the association with climate in each subtype of mood episodes.

RESULTS

Admission peaks were noted during spring/summer, early winter and early spring, for manic, depressive and mixed/unspecified episodes, respectively, while the associations with climatic parameters varied between the subtypes of mood episodes.

CONCLUSIONS

Seasonality in bipolar disorder does exist for all subtypes of mood episodes. The distinct seasonal patterns and various associations with the climatic parameters imply different underlying mechanisms for the onset of each subtype of mood episodes. The association between admission rates and certain climatic variables found in this study is informative and could pave the way for future studies aimed at exploring the influence of climate on the psychopathology of bipolar patients as well as the underlying mechanisms.

Seasonality of suicides with and without psychiatric illness in Denmark

This paper studied the seasonality of suicides among persons with and without psychiatric illness in Denmark from 1970 to 1999. A non-homogenous Poisson process was used to examine the data. The seasonality of suicides was shown to be associated with gender and their psychiatric histories with a declining trend of suicide incidence noted over the captured period. A mild seasonal component was reported in the period of the late 70s to early 80s (1975-1984) among females who did not have any psychiatric treatment history, while in the 80s the significant seasonality was mainly contributed by male suicides without a psychiatric history. Another mild possible invoked seasonality in the 90s was in males who suffered from psychiatric illness. The rest could be treated as random events. Apparently, the seasonality among suicides with psychiatric illness exists but its effect could vary in different periods of time and among genders in Denmark.