Solar insolation in springtime influences age of onset of bipolar I disorder

Can we predict a "tsunami"? Symptomatic and syndromal density, mood instability and treatment intensity in people with bipolar disorders under a strict and long lockdown

BACKGROUND

Converging evidence supports the involvement of circadian rhythm disturbances in the course and morbidity of bipolar disorders (BD). During 2020, lockdown measures were introduced worldwide to contain the health crisis caused by the COVID-19 pandemic. As a result, chronobiological rhythms were critically disrupted and illness outcomes were expected to worsen. The current study aimed to explore changes in morbidity among BD patients living under lockdown.

METHODS

Ninety BD outpatients under naturalistic treatment conditions were followed from March to September 2020 using a mood chart technique. Different treatment and illness variables, including mood instability, were assessed and compared with the outcomes obtained during the same 28-week period in 2019.

RESULTS

For most clinical variables, no significant differences were observed between time periods. A slight decrease was found in symptom intensity (from 15.19 ± 20.62 to 10.34 ± 15.79, FDR-adjusted p = 0.04) and in the number of depressive episodes (from 0.39 ± 0.74 to 0.22 ± 0.63, FDR-adjusted p = 0.03), whereas the intensity of pharmacological treatment remained unchanged. Previous illness course predicted mood outcomes during the confinement.

LIMITATIONS

Follow-up periods were relatively short. Further, actigraphy or other methods capable of ensuring significant changes in physical activity were not used.

CONCLUSIONS

In line with other studies, our findings show no worsening in the clinical morbidity of BD patients during lockdown. This conspicuous contrast between our initial predictions and the observed findings highlights the fact that we are still far from being able to provide accurate predictive models for BD.

Bipolar disorder: Diagnosis, treatment and future directions

Bipolar disorder is a relatively common mental illness, characterised by recurrent episodes of mania (or hypomania) and major depression, and associated with a significant burden of morbidity and premature mortality. Physicians across all specialities are likely to encounter individuals with the condition within their clinical practice. This short review provides an up-to-date overview of the clinical features, epidemiology, pathophysiology, evidence-based management, prognosis and future directions for treatment and research in bipolar disorder. Aspects of cross-specialty relevance are highlighted, including the physical health burden associated with the condition, and the side effects and safety considerations of medication regimes used in bipolar disorder.

Exploratory study of ultraviolet B (UVB) radiation and age of onset of bipolar disorder

BACKGROUND

Sunlight contains ultraviolet B (UVB) radiation that triggers the production of vitamin D by skin. Vitamin D has widespread effects on brain function in both developing and adult brains. However, many people live at latitudes (about > 40 N or S) that do not receive enough UVB in winter to produce vitamin D. This exploratory study investigated the association between the age of onset of bipolar I disorder and the threshold for UVB sufficient for vitamin D production in a large global sample.

METHODS

Data for 6972 patients with bipolar I disorder were obtained at 75 collection sites in 41 countries in both hemispheres. The best model to assess the relation between the threshold for UVB sufficient for vitamin D production and age of onset included 1 or more months below the threshold, family history of mood disorders, and birth cohort. All coefficients estimated at P ≤ 0.001.

RESULTS

The 6972 patients had an onset in 582 locations in 70 countries, with a mean age of onset of 25.6 years. Of the onset locations, 34.0% had at least 1 month below the threshold for UVB sufficient for vitamin D production. The age of onset at locations with 1 or more months of less than or equal to the threshold for UVB was 1.66 years younger.

CONCLUSION

UVB and vitamin D may have an important influence on the development of bipolar disorder. Study limitations included a lack of data on patient vitamin D levels, lifestyles, or supplement use. More study of the impacts of UVB and vitamin D in bipolar disorder is needed to evaluate this supposition.

Does circadian dysrhythmia drive the switch into high- or low-activation states in bipolar I disorder?

OBJECTIVES

Emerging evidence suggests a role of circadian dysrhythmia in the switch between "activation" states (i.e., objective motor activity and subjective energy) in bipolar I disorder.

METHODS

We examined the evidence with respect to four relevant questions: (1) Are natural or environmental exposures that can disrupt circadian rhythms also related to the switch into high-/low-activation states? (2) Are circadian dysrhythmias (e.g., altered rest/activity rhythms) associated with the switch into activation states in bipolar disorder? (3) Do interventions that affect the circadian system also affect activation states? (4) Are associations between circadian dysrhythmias and activation states influenced by other "third" factors?

RESULTS

Factors that naturally or experimentally alter circadian rhythms (e.g., light exposure) have been shown to relate to activation states; however future studies need to measure circadian rhythms contemporaneously with these natural/experimental factors. Actigraphic measures of circadian dysrhythmias are associated prospectively with the switch into high- or low-activation states, and more studies are needed to establish the most relevant prognostic actigraphy metrics in bipolar disorder. Interventions that can affect the circadian system (e.g., light therapy, lithium) can also reduce the switch into high-/low-activation states. Whether circadian rhythms mediate these clinical effects is an unknown but valuable question. The influence of age, sex, and other confounders on these associations needs to be better characterised.

CONCLUSION

Based on the reviewed evidence, our view is that circadian dysrhythmia is a plausible driver of transitions into high- and low-activation states and deserves prioritisation in research in bipolar disorders.

Bipolar Chronobiology in Men and Mice: A Narrative Review

In patients with bipolar disorder, we do not only see a cycling of mood episodes, but also a shift in circadian rhythm. In the present overview, the circadian rhythm, the "internal clock", and their disruptions are briefly described. In addition, influences on circadian rhythms such as sleep, genetics, and environment are discussed. This description is conducted with a translational focus covering human patients as well as animal models. Concluding the current knowledge on chronobiology and bipolar disorder, implications for specificity and the course of bipolar disorder and treatment options are given at the end of this article. Taken together, circadian rhythm disruption and bipolar disorder are strongly correlated; the exact causation, however, is still unclear.

Habitual light exposure and circadian activity rhythms in bipolar disorder: A cross-sectional analysis of the APPLE cohort

BACKGROUND

Circadian activity rhythm disruption is a core feature in bipolar disorder. We investigated whether light exposure in daily life is associated with circadian activity rhythms in patients with bipolar disorder.

METHODS

In a cross-sectional study, we enrolled 194 outpatients with bipolar disorder who were participants of the Association between Pathology of Bipolar Disorder and Light Exposure in Daily Life (APPLE) cohort study. The participants' physical activity and daytime illuminance were measured using an actigraph over 7 consecutive days. Nighttime illuminance in the bedroom was measured using a portable photometer. Circadian activity rhythm parameters were calculated using cosinor analysis and a nonparametric circadian rhythm analysis.

RESULTS

The median daytime illuminance and nighttime illuminance were 224.5 lx (interquartile range, 154.5-307.5 lx) and 2.3 lx (0.3-9.4 lx), respectively. Multivariable linear regression analysis, adjusted for potential confounding factors, showed that higher daytime illuminance was significantly associated with higher amplitude and most active continuous 10-hour period, advanced acrophase, higher interdaily stability, and lower intradaily variability. Higher nighttime illuminance was significantly associated with lower relative amplitude, delayed onset of the least active continuous 5-hour period, and higher intradaily variability.

LIMITATIONS

As this was a cross-sectional study, the results do not necessarily imply that light exposure alters circadian activity rhythms.

CONCLUSIONS

Daytime light exposure was associated with a positive effect and nighttime light exposure with a negative effect on circadian activity rhythms in bipolar disorder.

Association between polarity of first episode and solar insolation in bipolar I disorder

OBJECTIVE

Circadian rhythm disruption is commonly observed in bipolar disorder (BD). Daylight is the most powerful signal to entrain the human circadian clock system. This exploratory study investigated if solar insolation at the onset location was associated with the polarity of the first episode of BD I. Solar insolation is the amount of electromagnetic energy from the Sun striking a surface area of the Earth.

METHODS

Data from 7488 patients with BD I were collected at 75 sites in 42 countries. The first episode occurred at 591 onset locations in 67 countries at a wide range of latitudes in both hemispheres. Solar insolation values were obtained for every onset location, and the ratio of the minimum mean monthly insolation to the maximum mean monthly insolation was calculated. This ratio is largest near the equator (with little change in solar insolation over the year), and smallest near the poles (where winter insolation is very small compared to summer insolation). This ratio also applies to tropical locations which may have a cloudy wet and clear dry season, rather than winter and summer.

RESULTS

The larger the change in solar insolation throughout the year (smaller the ratio between the minimum monthly and maximum monthly values), the greater the likelihood the first episode polarity was depression. Other associated variables were being female and increasing percentage of gross domestic product spent on country health expenditures. (All coefficients: P ≤ 0.001).

CONCLUSION

Increased awareness and research into circadian dysfunction throughout the course of BD is warranted.

[Chronobiological aspects of bipolar disorder]

BACKGROUND

Numerous symptoms of bipolar disorder are regulated by the circadian rhythm. Because of this association it is assumed that disruption of the circadian rhythm may be part of the pathomechanism of bipolar disorder.

OBJECTIVES

A comparison and subsequent critical discussion of the current data situation on chronobiological aspects of bipolar disorder are presented.

METHODS

A narrative literature search was carried out and the main findings are presented in a summarized form.

RESULTS

There are a large number of animal and human studies investigating the connection between disorders of the circadian rhythm and bipolar disorder. Especially chronotype, the environmental factor light and sleep disorders seem to be associated with the development of bipolar disorder.

CONCLUSIONS

The neurobiology of bipolar disorder shows numerous chronobiological aspects. There is evidence for a direct connection of disruption of the circadian rhythm and development and progression of bipolar disorder; however, at present there is no proof for the specificity of these findings for bipolar disorder. Future studies should consolidate the evidence on the impact of disorders of the circadian rhythm on the pathomechanism of bipolar disorder.

A Review on Climate, Air Pollution, and Health in North Africa

PURPOSE OF REVIEW

The aim of this review is to summarize and provide clear insights into studies that evaluate the interaction between air pollution, climate, and health in North Africa.

RECENT FINDINGS

Few studies have estimated the effects of climate and air pollution on health in North Africa. Most of the studies highlighted the evidence of the link between climate and air pollution as driving factors and increased mortality and morbidity as health outcomes. Each North African country prioritized research on a specific health factor. It was observed that the health outcome from each driving factor depends on the studied area and data availability. The latter is a major challenge in the region. As such, more studies should be led in the future to cover more areas in North Africa and when more data are available. Data availability will help to explore the applicability of different tools and techniques new to the region. This review explores studies related to climate and air pollution, and their possible impacts on health in North Africa. On one hand, air quality studies have focused mainly on particulate matter exceedance levels and their long-term exposure impacts, namely, morbidity and mortality. The observed differences between the various studies are mainly due to the used exposure-response function, the studied population, background emissions, and natural emission from the Sahara Desert that characterize the region. On the other hand, climate studies have focused primarily on the impact of heat waves, vector-borne disease, and mental disorders. More than half of these studies have been on leishmaniasis disease. The review revealed unbalanced and insufficient research on health impacts from air pollution episodes and climate extremes across the region.

Neurobiological and behavioral mechanisms of circadian rhythm disruption in bipolar disorder: A critical multi-disciplinary literature review and agenda for future research from the ISBD task force on chronobiology

AIM

Symptoms of bipolar disorder (BD) include changes in mood, activity, energy, sleep, and appetite. Since many of these processes are regulated by circadian function, circadian rhythm disturbance has been examined as a biological feature underlying BD. The International Society for Bipolar Disorders Chronobiology Task Force (CTF) was commissioned to review evidence for neurobiological and behavioral mechanisms pertinent to BD.

METHOD

Drawing upon expertise in animal models, biomarkers, physiology, and behavior, CTF analyzed the relevant cross-disciplinary literature to precisely frame the discussion around circadian rhythm disruption in BD, highlight key findings, and for the first time integrate findings across levels of analysis to develop an internally consistent, coherent theoretical framework.

RESULTS

Evidence from multiple sources implicates the circadian system in mood regulation, with corresponding associations with BD diagnoses and mood-related traits reported across genetic, cellular, physiological, and behavioral domains. However, circadian disruption does not appear to be specific to BD and is present across a variety of high-risk, prodromal, and syndromic psychiatric disorders. Substantial variability and ambiguity among the definitions, concepts and assumptions underlying the research have limited replication and the emergence of consensus findings.

CONCLUSIONS

Future research in circadian rhythms and its role in BD is warranted. Well-powered studies that carefully define associations between BD-related and chronobiologically-related constructs, and integrate across levels of analysis will be most illuminating.

Supersensitivity of Patients With Bipolar I Disorder to Light-Induced Phase Delay by Narrow Bandwidth Blue Light

Background

Bipolar disorder is a severe chronic mental disorder. There is a bidirectional relationship between disease course and circadian phase. Significant circadian phase shifts occur during transitions between episodes, but episodes can also be elicited during euthymia by forced rapid changes in circadian phase. Although an instability of circadian phase has been described in multiple observational reports, no studies quantifying the propensity to phase shift following an experimental standardized stimulus have been published. This study therefore aimed to assess whether patients with bipolar I disorder (BDI) are more prone to phase delay following blue light exposure in the evening than healthy control subjects.

Methods

Euthymic participants with BDI confirmed by Structured Clinical Interview for DSM-IV Axis I (n = 32) and healthy control subjects (n = 55) underwent a 3-day phase shift protocol involving exposure to a standardized dose of homogeneous, constant, narrow bandwidth blue light (478 nm, half bandwidth = 18 nm, photon flux = 1.29 × 1015 photons/cm2/s) for 2 hours at 9:00 pm via a ganzfeld dome on day 2. On days 1 and 3, serial serum melatonin assessments during total darkness were performed to determine the dim light melatonin onset.

Results

Significant differences in the light-induced phase shift between BDI and healthy control subjects were detected (F 1,82 = 4.110; p = .046), with patients with bipolar disorder exhibiting an enhanced phase delay (η2 = 0.49). There were no significant associations between the magnitude of the phase shift and clinical parameters.

Conclusions

Supersensitivity of patients with BDI to light-induced phase delay may contribute to the observed phase instability and vulnerability to forced phase shifts associated with the disorder.

Variations in seasonal solar insolation are associated with a history of suicide attempts in bipolar I disorder

Background

Bipolar disorder is associated with circadian disruption and a high risk of suicidal behavior. In a previous exploratory study of patients with bipolar I disorder, we found that a history of suicide attempts was associated with differences between winter and summer levels of solar insolation. The purpose of this study was to confirm this finding using international data from 42% more collection sites and 25% more countries.

Methods

Data analyzed were from 71 prior and new collection sites in 40 countries at a wide range of latitudes. The analysis included 4876 patients with bipolar I disorder, 45% more data than previously analyzed. Of the patients, 1496 (30.7%) had a history of suicide attempt. Solar insolation data, the amount of the sun’s electromagnetic energy striking the surface of the earth, was obtained for each onset location (479 locations in 64 countries).

Results

This analysis confirmed the results of the exploratory study with the same best model and slightly better statistical significance. There was a significant inverse association between a history of suicide attempts and the ratio of mean winter insolation to mean summer insolation (mean winter insolation/mean summer insolation). This ratio is largest near the equator which has little change in solar insolation over the year, and smallest near the poles where the winter insolation is very small compared to the summer insolation. Other variables in the model associated with an increased risk of suicide attempts were a history of alcohol or substance abuse, female gender, and younger birth cohort. The winter/summer insolation ratio was also replaced with the ratio of minimum mean monthly insolation to the maximum mean monthly insolation to accommodate insolation patterns in the tropics, and nearly identical results were found. All estimated coefficients were significant at p < 0.01.

Conclusion

A large change in solar insolation, both between winter and summer and between the minimum and maximum monthly values, may increase the risk of suicide attempts in bipolar I disorder. With frequent circadian rhythm dysfunction and suicidal behavior in bipolar disorder, greater understanding of the optimal roles of daylight and electric lighting in circadian entrainment is needed.

Rate of change in solar insolation is a hidden variable that influences seasonal alterations in bipolar disorder

The consensus in the literature is that bipolar disorder is seasonal. We argue that there is finer detail to seasonality and that changes in mood and energy in bipolar disorder are dictated by the rate of change of solar insolation.

Effect of evening light exposure on sleep in bipolar disorder: A longitudinal analysis for repeated measures in the APPLE cohort

OBJECTIVE

Sleep disturbance, a core feature of bipolar disorder, is associated with residual mood symptoms, mood episode recurrence and suicide ideation. We investigated the effect of evening light exposure on sleep in patients with bipolar disorder.

METHODS

In this longitudinal analysis, we measured the sleep parameters of 207 outpatients with bipolar disorder using actigraphy at their homes for seven consecutive nights. We measured the white-light illuminance and the irradiance of each wavelength during the 4 hours before each participant's bedtime. We used mixed-effect linear regression analysis for repeated measures to evaluate the effect of evening light exposure on subsequent sleep parameters.

RESULTS

The median white-light illuminance was 25.8 lux (interquartile range, 12.9-50.1 lux). In a multivariable model adjusted for potential confounders, we found higher white-light illuminance to be significantly associated with lower sleep efficiency (per log lux: 95% confidence interval = [-1.328, -0.133]; p = 0.017), prolonged sleep-onset latency (95% confidence interval = [0.006, 0.172]; p = 0.035) and longer wake after sleep onset (95% confidence interval = [1.104, 4.459]; p = 0.001). This effect size was larger in the younger age group (aged < 44 years) stratified by median age. Higher irradiance of the blue wavelength range was significantly associated with longer wake after sleep onset, a result similar to those for the green and red wavelength ranges.

CONCLUSION

We observed significant associations between evening light exposure and subsequent sleep in patients with bipolar disorder. The effects of various light wavelengths on sleep in bipolar disorder require further investigation.

Sensitivity to Climate and Weather Changes in Euthymic Bipolar Subjects: Association With Suicide Attempts

BACKGROUND

Climate and weather are known to affect multiple areas of human life, including mental health. In bipolar disorder (BD), seasonality represents an environmental trigger for mood switches, and climatic variables may contribute to recurrences. Several studies reported seasonal and climatic-related variations in the rate of suicide attempts. Suicide risk is relevant in BD, with approximately 25% of patients attempting suicide. Therefore, this study aimed to assess sensitivity to weather and climatic variations in BD subjects and its relationship with lifetime suicide attempts.

METHODS

Three hundred fifty-two euthymic BD and 352 healthy control subjects, homogeneous with respect to socio-demographic characteristics, were enrolled. All participants were administered the METEO-Questionnaire (METEO-Q) to evaluate susceptibility to weather and climatic changes. We also investigated the potential relationship between sensitivity to climate and weather and lifetime suicide attempts in BD patients.

RESULTS

METEO-Q scores and the number of subjects reaching the cut-off for meteorosensitivity/meteoropathy were significantly higher in BD patients. Within the clinical group, BD subjects with lifetime suicide attempts obtained higher METEO-Q scores, with no differences between BD-I and BD-II. The number of suicide attempts directly correlated with METEO-Q scores. The presence of suicide attempts was associated with the physical and psychological symptoms related to weather variations.

DISCUSSION

Our findings support the relevance of sensitivity to weather and climate variations in a large sample of BD subjects and point out the association of this feature with lifetime suicide attempts.

Lighting as an aid for recovery in hospitalized psychiatric patients: a randomized controlled effectiveness trial

Purpose: Artificial indoor lighting can disturb sleep and increase depressive symptoms; both common complaints in psychiatric inpatients. In this trial we aimed to improve sleep in psychiatric inpatients using a circadian lighting environment.Patients and methods: Investigator-blinded parallel-group randomised controlled effectiveness trial in an inpatient psychiatric ward with adjustable lighting. Admitted patients received a pre-set circadian lighting environment (intervention group) or lighting as usual (control group). The primary outcome was the Pittsburg Sleep Quality Index (PSQI) and secondary outcomes included the Major Depression Inventory and WHO-5 Well-Being Index.Results: We assessed 74 patients and included 54 (27 treated and 27 controls). Treated patients reported a non-significant change in mean sleep quality by -1.02 points on the PSQI (95% CI: -3.17; 1.12) and controls by -0.59 points (95% CI: -2.52; 1.33), difference -0.43 (95% CI: -3.05; 2.2, p-value .74). Similarly, treated patients reported a non-significant change in depressive symptoms and well-being compared to controls. Qualitative data indicated no serious side-effects and no patients in the intervention group were submitted to involuntary measures. Collection of data was non-complete and missing data from self-reported questionnaires amounted to 52.5%.Conclusions: The intervention showed no effect on sleep quality, mood or well-being. The circadian lighting environment was safe in our small and diverse patient sample. The trial integrated well with routine clinical care and our sample reflected the heterogeneity of the target population.

Light exposure at night and sleep quality in bipolar disorder: The APPLE cohort study

BACKGROUND

Sleep disturbance in bipolar disorder (BD) is common and is associated with a risk for mood episode recurrence. Thus, it is important to identify factors that are related to sleep disturbance in BD. This cross-sectional study investigated the association between exposure to light at night (LAN) and sleep parameters in patients with BD.

METHODS

The sleep parameters of 175 outpatients with BD were recorded using actigraphy at their homes for seven consecutive nights and were evaluated using the Insomnia Severity Index (ISI). The average LAN intensity in the bedroom during bedtime and rising time was measured using a portable photometer, and the participants were divided into two groups: "Light" (≥5 lx) and "Dark" (<5 lx). The association between LAN and sleep parameters was tested with multivariable analysis by adjusting for potential confounder such as age, gender, current smoker, mood state, day length, daytime light exposure, and sedative medications.

RESULTS

After adjusting for potential confounder, the actigraphy sleep parameters showed significantly lower sleep efficiency (mean, 80.1%vs. 83.4%; p = 0.01), longer log-transformed sleep onset latency (2.9 vs. 2.6 min; p = 0.01), and greater wake after sleep onset (51.4 vs. 41.6 min; p = 0.02) in the Light group than in the Dark group. Whereas, there were no significant differences in the ISI scores between the groups.

LIMITATIONS

This was a cross-sectional study; therefore, the results do not necessarily imply that LAN causes sleep disturbance.

CONCLUSIONS

Reducing LAN exposure may contribute to improved sleep quality in patients with BD.

Association between solar insolation and a history of suicide attempts in bipolar I disorder

In many international studies, rates of completed suicide and suicide attempts have a seasonal pattern that peaks in spring or summer. This exploratory study investigated the association between solar insolation and a history of suicide attempt in patients with bipolar I disorder. Solar insolation is the amount of electromagnetic energy from the Sun striking a surface area on Earth. Data were collected previously from 5536 patients with bipolar I disorder at 50 collection sites in 32 countries at a wide range of latitudes in both hemispheres. Suicide related data were available for 3365 patients from 310 onset locations in 51 countries. 1047 (31.1%) had a history of suicide attempt. There was a significant inverse association between a history of suicide attempt and the ratio of mean winter solar insolation/mean summer solar insolation. This ratio is smallest near the poles where the winter insolation is very small compared to the summer insolation. This ratio is largest near the equator where there is relatively little variation in the insolation over the year. Other variables in the model that were positively associated with suicide attempt were being female, a history of alcohol or substance abuse, and being in a younger birth cohort. Living in a country with a state-sponsored religion decreased the association. (All estimated coefficients p < 0.01). In summary, living in locations with large changes in solar insolation between winter and summer may be associated with increased suicide attempts in patients with bipolar disorder. Further investigation of the impacts of solar insolation on the course of bipolar disorder is needed.

Exposure-lag-response association between sunlight and schizophrenia in Ningbo, China

Previous studies found that mental disorders such as bipolar disorder, seasonal affective disorder and schizophrenia, often show seasonal variability, which usually be attributed to the variations in the number of natural sunlight. However, few studies have been conducted on the acute effects of exposure to sunlight on the onset of these disease. The aim of this study was to evaluate the exposure-response relationship between sunshine duration and the hospital admissions for schizophrenia. We obtained data on hospital admissions for schizophrenia from the largest psychiatric hospital in Ningbo, China, during 2012-2016. A Distributed lag non-linear model was used to estimate the exposure-lag-response relationship between sunlight and schizophrenia. We calculated the effects of short and long sunshine duration, defined using the cutoffs at the 1st and 99th sunshine duration percentiles. We detected significant and non-linear associations between sunlight and schizophrenia, and the overall estimated relative risk (RR) for a lag of 0-21 days was 1.45 (95% CI: 1.07, 1.97) and 1.41(95% CI: 0.72, 2.75) for short and long sunshine duration, respectively. The burden of schizophrenia was greater during periods with short sunshine duration than during periods with long sunshine duration, with the AFs of 19.94% (95% CI: 8.65%, 28.24%) and 2.12% (95% CI: -2.70%, 5.57%), respectively. The female and people more than 45 years old were most susceptible to these effects. We repeated our analysis by using global solar radiation as a continuous exposure variable of sunlight intensity in the model, and the result shows that the female and middle-aged and eldly patients were also susceptible to the effects of low levels of global solar radiation. Our findings suggest that there may be a relationship between lack of exposure to sunlight and increased risk of hospital admissions for schizophrenia. Policymakers and doctors should promote further understanding of the health benefits of sunlight and take effective measures to prevent schizophrenia.

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

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

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.

Bipolar disorders

Bipolar disorders are chronic and recurrent disorders that affect >1% of the global population. Bipolar disorders are leading causes of disability in young people as they can lead to cognitive and functional impairment and increased mortality, particularly from suicide and cardiovascular disease. Psychiatric and nonpsychiatric medical comorbidities are common in patients and might also contribute to increased mortality. Bipolar disorders are some of the most heritable psychiatric disorders, although a model with gene-environment interactions is believed to best explain the aetiology. Early and accurate diagnosis is difficult in clinical practice as the onset of bipolar disorder is commonly characterized by nonspecific symptoms, mood lability or a depressive episode, which can be similar in presentation to unipolar depression. Moreover, patients and their families do not always understand the significance of their symptoms, especially with hypomanic or manic symptoms. As specific biomarkers for bipolar disorders are not yet available, careful clinical assessment remains the cornerstone of diagnosis. The detection of hypomanic symptoms and longtudinal clinical assessment are crucial to differentiate a bipolar disorder from other conditions. Optimal early treatment of patients with evidence-based medication (typically mood stabilizers and antipsychotics) and psychosocial strategies is necessary.

Seasonality in trauma admissions - Are daylight and weather variables better predictors than general cyclic effects?

Background

Trauma is a leading global cause of death, and predicting the burden of trauma admissions is vital for good planning of trauma care. Seasonality in trauma admissions has been found in several studies. Seasonal fluctuations in daylight hours, temperature and weather affect social and cultural practices but also individual neuroendocrine rhythms that may ultimately modify behaviour and potentially predispose to trauma. The aim of the present study was to explore to what extent the observed seasonality in daily trauma admissions could be explained by changes in daylight and weather variables throughout the year.

Methods

Retrospective registry study on trauma admissions in the 10-year period 2001–2010 at Oslo University Hospital, Ullevål, Norway, where the amount of daylight varies from less than 6 hours to almost 19 hours per day throughout the year. Daily number of admissions was analysed by fitting non-linear Poisson time series regression models, simultaneously adjusting for several layers of temporal patterns, including a non-linear long-term trend and both seasonal and weekly cyclic effects. Five daylight and weather variables were explored, including hours of daylight and amount of precipitation. Models were compared using Akaike’s Information Criterion (AIC).

Results

A regression model including daylight and weather variables significantly outperformed a traditional seasonality model in terms of AIC. A cyclic week effect was significant in all models.

Conclusion

Daylight and weather variables are better predictors of seasonality in daily trauma admissions than mere information on day-of-year.