The influence of climate on development of winter depression

Research status, hotspots, and implications of seasonal affective disorder: A bibliometric analysis based on CiteSpace and VOSviewer

The objective was to determine the research status and hotspots of seasonal affective disorders (SAD) based on bibliometric tools, which will contribute to the further research in this field. We used bibliometric tools CiteSpace and VOSviewer to conduct visual quantitative analysis on 465 SAD literatures in the Web of Science core database from 2008 to 2023 from multiple perspectives such as collaboration network, keywords, and literature citations. At the same time, we used Microsoft Word to make relevant tables. The publication of SAD-related literature has been on the rise in the past 15 years, countries with high production of SAD literature are mainly concentrated in the United States, Austria, and Canada, and certain cooperative relationships have been established between various institutions and scholars. Research keywords in our study are mainly limited to pathogenesis ("Photoperiod," "exposure," "winter," "serotonin transporter," and "creb") and treatment measures ("light therapy" and "melatonin"). In recent years, literature research hotspots mainly focus on the treatment of SAD with light therapy, the application of exogenous drugs, the biological clock mechanism of SAD pathogenesis, the relationship between SAD and inflammation, etc. The correlation between SAD and sleepiness and alternative treatments to light therapy may be future research hotspots. The research results reveal the future research focus of SAD. There is a considerable interest in the photoperiodic pathogenesis of SAD, light therapy and its alternative therapies, and there is still hope for further exploration. Substantial research into evidence-based prevention as well as treatment strategies is necessary to improve outcomes.

The Role of Season, Sunlight, and Light Sensitivity in Self-Reported Depressive Symptoms by Adults With Visual Impairment

Purpose

Depression is common in people with visual impairment, and the onset may be influenced by aspects related to light. The aim was to explore the associations of season, sunlight, and light sensitivity with depressive symptoms in this population.

Methods

Data regarding self-reported depressive symptoms from seven cross-sectional studies conducted between 2009 and 2018 were combined with information concerning sensitivity to light, season on the date of self-report, and potential sunlight exposure in the 2 weeks prior to self-report. The latter was calculated by summing up the daily sunlight hours detected by the weather station nearest to the residence of each participant. Logistic regression analyses were performed to investigate the associations.

Results

Participants (N = 1925) experienced clinically significant depressive symptoms most often in winter (32.8%), followed by summer (27.4%), spring (26.2%), and fall (24.2%). The odds of experiencing depression in fall were significantly lower compared with winter (odds ratio [OR] = 0.67, P = 0.007). An increase in the hours of sunlight in the participant's environment was associated with lower odds to experience depressive symptoms (OR = 0.995, P = 0.011). People who were sensitive to bright light had higher odds of experiencing depressive symptoms (OR = 1.80, P < 0.001). Other differences found between subgroups were not consistent.

Conclusions

It seems likely that season, sunlight, and light sensitivity play a role in depression among people with visual impairment. Further research is needed, exploring the experiences in this population, the actual sunlight exposure using objective measures, and treatment options.

Translational Relevance

Clinicians should consider these factors when treating visually impaired patients with depressive symptoms.

Cold weather isolation is worse in poor and non-white neighborhoods in the United States

Social isolation can cause a variety of adverse physical and mental health effects and is central to understanding broader social disparities among marginalized groups in the United States. This study aims to assess whether temperature variation is associated with daily social isolation at the neighborhood level. I test a series of two-way fixed effects models to see if mean daily temperature is associated with individuals spending the entire day at home, as measured using smartphone data, across a sample of 45 million devices in 2019 in the United States. Using interaction terms, I specifically examine heterogeneity in temperature effects by neighborhood racial composition and socioeconomic status. The two-way fixed effects models reveal highly statistically significant negative coefficients for the interaction between temperature and neighborhood proportion Black, temperature and neighborhood proportion Hispanic, and temperature and neighborhood residential disadvantage, in predicting the probability of spending the entire day at home. In marginal terms, the findings indicate the gap in the probability of spending the entire day at home between an all-Black neighborhood and an all-White neighborhood grows by nearly 10 percentage points from the warmest day of the year to the coldest day of the year in some parts of the United States. My models highlight how residents of poor and majority Black and Hispanic neighborhoods experience disproportionate social isolation in the form of a greater propensity to spend the entire day at home.

The underexplored presence of seasonal affective disorder in the southern hemisphere: A narrative review of the Australian literature

BACKGROUND

Seasonal Affective Disorder (SAD) is well documented in the medical literature, particularly in more northern latitudes in agreement with proposed hypotheses for SAD's pathophysiology. However, in the southern latitudes SAD's presence remains underexplored. The second largest country in the southern hemisphere is Australia. Australia has wide ranging geographical and climatic differences that are expected to support SAD's presence. The aim of this study is therefore, to establish an evidence base for SAD in Australia.

METHODS

PubMed and Google Scholar were searched for published peer-review studies focussed on, or related to SAD, winter depression or seasonal variation in mood in Australia. There were no time-period restrictions.

RESULTS

Thirteen studies were identified. Studies explored the presence/nature of SAD, contributing factors, autonomic activity, treatment, and the validity of the Seasonal Pattern Assessment Questionnaire in the Australian population. An association between changes in mood and behaviour and seasonal occurrence was clearly identified, with SAD's presence varying by location. The highest percentage of study participants with SAD in a single location was observed in Tasmania, Australia's most southern state. The findings and interpretations of the studies included in this review are subject to the number of locations assessed, the number of studies undertaken at each location and individual study limitations.

CONCLUSIONS

Ascertaining information on the prevalence and correlates of SAD in the southern hemisphere, particularly in high-risk locations could contribute to clinical literacy into the syndrome, support management practices, and promote the early identification and treatment of the disorder.

Effects of sunshine duration on daily outpatient visits for depression in Suzhou, Anhui Province, China

Previous epidemiological studies have reported seasonal variation patterns of depression symptoms, which may be influenced by bad weather conditions, such as a lack of sunlight. However, evidence on the acute effects of sunshine duration on outpatient visits for depression is limited, especially in developing countries, and the results are inconsistent. We collected daily outpatient visits for depression from the local mental health centre in Suzhou, Anhui Province, China, during 2017-2019. We defined the 5th and 95th sunshine percentiles as short and long sunshine durations, respectively. A quasi-Poisson generalized linear regression model combined with a distributed lag nonlinear model was used to quantitatively assess the effects of short and long sunshine durations on outpatient visits for depression. Stratified analyses were further performed by gender, age and number of visits to identify vulnerable populations. A total of 26,343 depression cases were collected during the study period. An approximate U-shaped exposure-response association was observed between sunshine duration and depression outpatient visits. The cumulative estimated relative risks (RRs) for short and long sunshine durations at lag 0-21 days were 1.53 [95% confidence intervals (CI): 1.14, 2.06] and 1.13 (95% CI: 0.88, 1.44), respectively. Moreover, a short sunshine duration was associated with a greater disease burden than a long sunshine duration, with attributable fractions (AFs) of 16.64% (95% CI: 7.8%, 23.89%) and 2.24% (95% CI: -2.65%, 5.74%), respectively. Subgroup analysis showed that males, people aged less than 45 years and first-visit cases may be more susceptible to a lack of sunlight. For a long sunshine duration, no statistically significant associations were found in any population groups. Our study found that a short sunshine duration was associated with an increased risk of depression. The government, medical institutions, family members and patients themselves should fully recognize the important role of sunlight and take active measures to prevent depression.

Effects of extreme precipitation on hospital visit risk and disease burden of depression in Suzhou, China

Background

The purpose of this study was to explore the impact of extreme precipitation on the risk of outpatient visits for depression and to further explore its associated disease burden and vulnerable population.

Methods

A quasi-Poisson generalized linear regression model combined with distributed lag non-linear model (DLNM) was used to investigate the exposure-lag-response relationship between extreme precipitation (≥95th percentile) and depression outpatient visits from 2017 to 2019 in Suzhou city, Anhui Province, China.

Results

Extreme precipitation was positively associated with the outpatient visits for depression. The effects of extreme precipitation on depression firstly appeared at lag4 [relative risk (RR): 1.047, 95% confidence interval (CI): 1.005–1.091] and lasted until lag7 (RR = 1.047, 95% CI: 1.009–1.087). Females, patients aged ≥65 years and patients with multiple outpatient visits appeared to be more sensitive to extreme precipitation. The attributable fraction (AF) and numbers (AN) of extreme precipitation on outpatient visits for depression were 5.00% (95% CI: 1.02–8.82%) and 1318.25, respectively.

Conclusions

Our findings suggested that extreme precipitation may increase the risk of outpatient visits for depression. Further studies on the burden of depression found that females, aged ≥65 years, and patients with multiple visits were priority targets for future warnings. Active intervention measures against extreme precipitation events should be taken to reduce the risk of depression outpatient visits.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-14085-w.

Recordkeeping Error or Strategic Seasonal Substitution?: The Seasonality of Occupational Injuries in SOII and MarketScan

OBJECTIVE

I compare the seasonal patterns observed in the Survey of Occupational Injuries and Illnesses (SOII) to claims data from the IBM® MarketScan® Research Databases.

METHODS

I construct monthly injury rates and claims rates by supplementing occupational injuries and other claims data with hours data from the Current Population Survey and estimate seasonal effects using an Unobservable Components Model.

RESULTS

While workers' compensation data and the SOII display similar seasonal patterns, the year-end decline in the MarketScan data is 1/3 to 1/2 the magnitude observed in the SOII. Short-term disability and private health insurance claims display seasonal patterns inversely related to occupational injuries.

CONCLUSIONS

Part of the year-end decline in occupational injuries observed in the SOII is likely due to recordkeeping error. There is also some evidence of strategic seasonal substitution between various health-compensation alternatives.

The effect of the brightness metaphor on memory

Brightness-based metaphor effects on perception have been widely documented. For example, moral content makes perception brighter. But does moral content make a bright memory brighter? We tested the effect of the moral brightness metaphor on different cognitive processes (perception, working memory, and long-term memory), and extended evidence of the relationship between brightness and moral concepts to the relationship between brightness and positive concepts. Different samples of college students participated in five experiments. In all experiments, moral (immoral) and positive (negative) pictures of varying levels of brightness were presented, and then participants reconstructed the brightness of each picture using a keyboard to adjust the brightness of an picture. Together, the results of ANOVAs across experiments showed that the metaphorical effect of brightness played no role in perception or working memory, but there was a significant increase in brightness in long-term memory. These results support the non-unidirectionality of metaphor, and extend the conceptual metaphor theory and simulating sensorimotor metaphors theory by enhancing the effect of metaphor through the cognitive mechanism of long-term memory.

Synodic lunar phases and suicide: based on 2605 suicides over 23 years, a full moon peak is apparent in premenopausal women from northern Finland

Suicide data for this study were available for the period of March 1988 to June 2011, and involved 2111 male and 494 female victims from the Finnish province of Oulu. Data for lunar phases during that period were categorised into three groups: new moon (<25% visible), full moon (>75% visible) and other times with values in between. Seasonal effects were controlled with definitions for winter (Nov, Dec, Jan), spring (Feb, Mar, Apr), summer (May, June, July), and autumn (Aug, Sep, Oct). Suicide occurrences during different lunar phases were compared with their expected distribution using multinomial tests with all tests being two-tailed. Statistical significance was set at p < 0.05. No correlation between suicides and moon phase in any of the four seasons was apparent for male victims, but in winter for women it was (p = 0.001). Further analysis of the data revealed that the full moon association was statistically significant only for premenopausal women, defined as female victims younger than 45 years of age. To explain this unexpected finding a number of factors were considered, e.g., the darkness of a northern Finnish winter with increases of SAD and depression especially in premenopausal women, the influence of the lunar periodicity on the menstrual cycle, and cosmogeophysical effects on the humoral and autonomous nervous system.

A Data-Driven Analysis of Sociocultural, Ecological, and Economic Correlates of Depression Across Nations

The prevalence of depression varies widely across nations, but we do not yet understand what underlies this variation. Here we use estimates from the Global Burden of Disease study to analyze the correlates of depression across 195 countries and territories. We begin by identifying potential cross-correlates of depression using past clinical and cultural psychology literature. We then take a data-driven approach to modeling which factors correlate with depression in zero-order analyses, and in a multiple regression model that controls for covariation between factors. Our findings reveal several potential correlates of depression, including cultural individualism, daylight hours, divorce rate, and GDP per capita. Cultural individualism is the only factor that remains significant across all our models, even when adjusting for spatial autocorrelation, mental healthcare workers per capita, multicollinearity, and outliers. These findings shed light on how depression varies around the world, the sociocultural and environmental factors that underlie this variation, and potential future directions for the study of culture and mental illness.

The effect of climate change on depression in urban areas of western Iran

Objective

Human is accustomed to climatic conditions of the environment where they are born and live throughout their lifetime. The aim of this study is to examine mood swings and depression caused by sudden climate changes that have not yet given the humans a chance to adapt.

Results

Our results showed that depression could be affected by climate change and as a result, the behavior of climatic elements and trends has damaged mental health in the western regions of Iran. By investigating the trends and changes of climatic time series and their relationship with the rate of depression in urban areas of western Iran, it can be said that climate change is probably a mental health challenge for urban populations. Climate change is an important and worrying issue that makes the life difficult. Rapid climate changes in western Iran including rising air temperature, changes in precipitation, its regime, changes cloudiness and the amount of sunlight have a negative effects on health. The results showed that type of increasing or decreasing trend, as well as different climatic elements in various seasons did not have the same effect on the rate of depression in the studied areas.

Is ionizing radiation a risk factor for anxiety in employees?

OBJECTIVE

Workers describe many physical and mental symptoms when working in radiation areas. This study aimed to assess these symptoms in radiation workers using the Beck Anxiety Inventory (BAI).

METHODS

A total of 42 radiation workers (22 males and 20 females, mean age 34±7 years) and 47 control subjects (22 males and 27 females, mean age 31± 8 years) who work in non-radiation areas in the hospital were included in the study. All participants anonymously filled out the Beck Anxiety Inventory (BAI) questionnaire.

RESULTS

The demographic data of workers were not significantly different between groups. In the BAI, the dizzy or lightheaded (p =0.01), terrified (p= 0.01), unsteady (p=0.02), heart-pounding and racing (p=0.02) items were significantly higher in the radiation-exposed group compared to the control group. |The BAI score was also significantly higher in the radiation-exposed group (11.1±6.8 vs. 8.7±3.8, p =0.04).

CONCLUSION

These results suggest the possibility that radiation may play a role in the psychometric properties of workers. The effects of radiation on the health of employees need to be further investigated and understood.

Antidepressant Effect of Blue Light on Depressive Phenotype in Light-Deprived Male Rats

Blue light has been previously reported to play a salient role in the treatment of seasonal affective disorder. The present study aimed to investigate whether blue light had antidepressant effect on light-deprivation-induced depression model, and the underlying visual neural mechanism. Blue light mitigated depression-like behaviors induced by light deprivation as measured by elevated sucrose preference and reduced immobility time. Blue light enhanced melanopsin expression and light responses in the retina. We also found the upregulation of serotonin and brain derived neurotrophic factor expression in the c-fos-positive areas of rats treated with blue light compared with those maintained in darkness. The species gap between nocturnal albino (Sprague-Dawley rat) and diurnal pigmented animals (human) might have influenced extrapolating data to humans. Blue light has antidepressant effect on light-deprived Sprague-Dawley rats, which might be related to activating the serotonergic system and neurotrophic activity via the retinoraphe and retinoamygdala pathways. Blue light is the effective component of light therapy for treatment of depression.

Frontal cerebral oxygenation asymmetry: intersubject variability and dependence on systemic physiology, season, and time of day

Significance: Our study reveals that frontal cerebral oxygenation asymmetry (FCOA), i.e. a difference in the oxygenation between the right and left prefrontal cortex (PFC), is a real phenomenon in healthy human subjects at rest. Aim: To investigate FCOA, we performed a study with 134 healthy right-handed subjects with the systemic physiology augmented functional near infrared spectroscopy (SPA-fNIRS) approach. Approach: Subjects were measured 2 to 4 times on different days resulting in an unprecedented number of 518 single measurements of the absolute values of tissue oxygen saturation (StO 2 ) and total hemoglobin concentration ([tHb]) of the right and left PFC. Measurements were performed with frequency-domain functional near-infrared spectroscopy. In addition, the cardiorespiratory parameters were measured simultaneously. Results: We found that (i) subjects showed an FCOA (higherStO 2 on the right PFC), but not for tHb; (ii) intrasubject variability was excellent for bothStO 2 and tHb, and fair for FCOA; (iii) StO 2 correlated significantly with bloodCO 2 concentration, [tHb] with heart rate, respiration rate (RR), and the pulse-respiration quotient (PRQ), and FCOA with RR and PRQ; (iv) FCOA andStO 2 were dependent on season and time of day, respectively; (v) FCOA was negatively correlated with the room temperature; and (vi) StO 2 and tHb were not correlated with the subjects mood but with their chronotype, whereas FCOA was not dependent on the chronotype. Conclusion: Our study demonstrates that FCOA is real, and it provides unique insights into this remarkable phenomenon.

Mood and behavior seasonality in glaucoma; assessing correlations between seasonality and structure and function of the retinal ganglion cells

Aim

In glaucoma, depression and disturbed sleep has been associated with degeneration of the intrinsically photosensitive retinal ganglion cells, that mediate non-image forming effects of light such as regulation of circadian rhythm, alertness and mood. In this study we assessed associations between seasonal mood and behavior variation and retinal ganglion cell damage in outpatients with glaucoma.

Methods

The seasonal pattern assessment questionnaire was administered to outpatients with glaucoma. Data on visual field defects identified by autoperimetry and retinal nerve fiber layer thickness visualized by ocular coherence tomography were collected from patient charts. The correlations between seasonality and retinal damage were tested and the adjusted effects of retinal function on seasonality were evaluated in a linear regression model.

Results

In total, 113 persons completed the questionnaire. Of these, 4% fulfilled the criteria for seasonal affective disorder (SAD) and 8% for subsyndromal seasonal affective disorder (sSAD). Mean global seasonal score was 4.3. There were no significant correlations between seasonality and either visual field or retinal nerve fiber layer thickness. In the adjusted analysis there were trends toward differential effects of visual field on seasonality in subgroups with different sex and type of glaucoma.

Conclusion

There were no strong associations between seasonality and visual field or retinal nerve fiber layer thickness. Sex, age and glaucoma subtype may modify light effects on complex regulatory systems.

Out of the dark, into the light: The impact of social exclusion on judgments of darkness and brightness

Based on theories of grounded cognition, we assumed that the experience of social exclusion is grounded in a concept of darkness. Specifically, we hypothesized that social exclusion causes perceptual judgments of darkness and a preference for brightness as a compensatory response. To investigate these hypotheses, we conducted four studies using different manipulations and measurements. In Studies 1a and 1b, excluded participants judged a picturized room as darker and drew more attention to its brightest part than included participants. In Study 2, excluded participants judged a surface as darker and decided for brighter clothing than included participants. In Study 3, excluded participants judged their lab room as darker and expressed a higher preference for brightness than included participants. Providing consistent support for our hypotheses, these findings confirm the idea that the experience of social exclusion is grounded in multiple ways that share a common representational system.

Correlation Analysis to Identify the Effective Data in Machine Learning: Prediction of Depressive Disorder and Emotion States

Correlation analysis is an extensively used technique that identifies interesting relationships in data. These relationships help us realize the relevance of attributes with respect to the target class to be predicted. This study has exploited correlation analysis and machine learning-based approaches to identify relevant attributes in the dataset which have a significant impact on classifying a patient’s mental health status. For mental health situations, correlation analysis has been performed in Weka, which involves a dataset of depressive disorder symptoms and situations based on weather conditions, as well as emotion classification based on physiological sensor readings. Pearson’s product moment correlation and other different classification algorithms have been utilized for this analysis. The results show interesting correlations in weather attributes for bipolar patients, as well as in features extracted from physiological data for emotional states.

Brain monoamine oxidase A in seasonal affective disorder and treatment with bright light therapy

Increased cerebral monoamine oxidase A (MAO-A) levels have been shown in non-seasonal depression using positron emission tomography (PET). Seasonal affective disorder (SAD) is a sub-form of major depressive disorder and is typically treated with bright light therapy (BLT). The serotonergic system is affected by season and light. Hence, this study aims to assess the relevance of brain MAO-A levels to the pathophysiology and treatment of SAD. Changes to cerebral MAO-A distribution (1) in SAD in comparison to healthy controls (HC), (2) after treatment with BLT and (3) between the seasons, were investigated in 24 patients with SAD and 27 HC using [¹¹C]harmine PET. PET scans were performed in fall/winter before and after 3 weeks of placebo-controlled BLT, as well as in spring/summer. Cerebral MAO-A distribution volume (V_T, an index of MAO-A density) did not differ between patients and HC at any of the three time-points. However, MAO-A V_T decreased from fall/winter to spring/summer in the HC group (F_{1, 187.84} = 4.79, p < 0.050), while SAD showed no change. In addition, BLT, but not placebo, resulted in a significant reduction in MAO-A V_T (F_{1, 208.92} = 25.96, p < 0.001). This is the first study to demonstrate an influence of BLT on human cerebral MAO-A levels in vivo. Furthermore, we show that SAD may lack seasonal dynamics in brain MAO-A levels. The lack of a cross-sectional difference between patients and HC, in contrast to studies in non-seasonal depression, may be due to the milder symptoms typically shown by patients with SAD.

Meteorological parameters and air pollen count in association with self-reported peripartum depressive symptoms

BACKGROUND

Meteorological parameters and air pollen count have been associated with affective disorders and suicide. Regarding peripartum depression, the literature is restricted and inconclusive.

METHODS

This cross-sectional study included women (pregnant, n = 3843; postpartum, n = 3757) who participated in the BASIC (Biology, Affect, Stress, Imaging, and Cognition) study 2010-2015 and the UPPSAT (Uppsala-Athens) study (postpartum, n = 1565) in 2006-2007. Cases were defined according to presence of depressive symptoms during pregnancy (gestational week 32) and 6 weeks postpartum, using the Edinburgh Postnatal Depression Scale (EPDS). Exposure of sunshine, temperature, precipitation, snow coverage, and air pollen counts of durations of 1, 7, and 42 days prior to the outcome were studied for associations with depressive symptoms, using negative binomial regression.

RESULTS

Prior to Bonferroni correction, the concentration of mugwort pollen, both one week and six weeks before the EPDS assessment at gestational week 32, was inversely associated with depressive symptoms in pregnancy, both before and after adjustment for season. No associations were found between the exposure to meteorological parameters and pollen and depressive symptoms, at the same day of depressive symptoms' assessment, the previous week, or the six weeks prior to assessment, either during pregnancy or postpartum after Bonferroni correction.

CONCLUSIONS

There was no evidence that neither short-term nor long-term exposure to meteorological parameters or air pollen counts were associated with self-reported peripartum depressive symptoms in Uppsala, Sweden.

Effects of genetic variants of ST8SIA2 and NCAM1 genes on seasonal mood changes and circadian preference in the general population

ST8SIA2 and NCAM1 are functionally related genes forming polysialic acid (PSA) - neural cell adhesion molecule (NCAM) complex in suprachiasmatic nucleus (SCN), the regulating site of circadian biological rhythm. In this study, the relationship of ST8SIA2 and NCAM1 with circadian and seasonal rhythms of human behavior was explored. Subjects were 261 healthy Korean adults who were free of any history of clinically significant psychiatric symptoms. The phenotypes were circadian preference and seasonal change of mood and behavior (seasonality) measured by the Composite Scale of Morningness and the Seasonal Pattern Assessment Questionnaire, respectively. Thirty-four single nucleotide polymorphisms (SNPs) across the ST8SIA2 region and 15 SNPs of NCAM1 were analyzed. A nominally significant association with seasonality and circadian preference was observed in 21 variants of both genes. After corrections for multiple testing, associations of 8 SNPs of ST8SIA2 and 2 SNPs of NCAM1 with seasonality remained significant. Some of these SNPs were also associated with psychiatric disorders in previous studies. This study demonstrated a meaningful and/or suggestive evidence of association between behavioral phenotypes reflecting human biological rhythm and two interplaying genes involved in the plasticity of SCN's neuronal network.

Meteorological analysis of symptom data for people with seasonal affective disorder

It is thought that variation in natural light levels affect people with Seasonal Affective Disorder (SAD). Several meteorological factors related to luminance can be forecast but little is known about which factors are most indicative of worsening SAD symptoms. The aim of this meteorological analysis is to determine which factors are linked to SAD symptoms. The symptoms of 291 individuals with SAD in and near Groningen have been evaluated over the period 2003-2009. Meteorological factors linked to periods of low natural light (sunshine, global radiation, horizontal visibility, cloud cover and mist) and others (temperature, humidity and pressure) were obtained from weather observation stations. A Bayesian zero adjusted auto-correlated multilevel Poisson model was carried out to assess which variables influence the SAD symptom score BDI-II. The outcome of the study suggests that the variable sunshine duration, for both the current and previous week, and global radiation for the previous week, are significantly linked to SAD symptoms.

Association between temperature and maternal stress during pregnancy

BACKGROUND

Maternal psychological stress during pregnancy has essentially been conceptualized as a teratogen. However, little is known about the effect of temperature on maternal stress during pregnancy. The aim of this study is to investigate the relationship between temperature and maternal stress during pregnancy.

METHODS

In 2010, a total of 1931 eligible pregnant women were enrolled across Shanghai from four prenatal-care clinics during their mid-to-late pregnancy. Maternal life-event stress and emotional stress levels during pregnancy were assessed by the "Life Event Scale for Pregnant Women" (LESPW) and "Symptom Checklist-90-Revised Scale" (SCL-90-R), respectively. Exposure to ambient temperature was evaluated based on daily regional average in different moving average and lag days. The generalized estimating equations were used to evaluate the relationship between daily average temperature/temperature difference and maternal stress.

RESULTS

After adjusting for relevant confounders, an U-shaped relationship was observed between daily average temperature and maternal Global-Severity-Index (GSI) of the SCL-90-R. Cumulative exposures to extremely low temperatures (< P5, 1.4-10.5℃, lag 0-1 days, 0-2 days and 0-5 days) and extremely high temperatures (≥ P95, 31.2-34.1℃, lag 0-1 days and 0-2 days), and acute exposures to extremely low (lag day 0, 1, 2 and 3) and high (lag day 0, 1) temperatures, all induced higher risks of high GSI (the highest tertile), compared to the risk induced by exposed to an optimal temperature range (20-25℃) (P< 0.05). Increased temperature difference was associated with high maternal GSI (P< 0.05). However, non-significant associations were observed between daily average temperatures/temperature differences and maternal log-transferred LESPW scores.

CONCLUSIONS

Cumulative and acute exposures to extremely low/high temperatures may both induce emotional stress during pregnancy.

Let the sunshine in? The effects of luminance on economic preferences, choice consistency and dominance violations

Weather, in particular the intensity and duration of sunshine (luminance), has been shown to significantly affect financial markets. Yet, because of the complexity of market interactions we do not know how human behavior is affected by luminance in a way that could inform theoretical choice models. In this paper, we use data from a field study using an incentive-compatible, decision task conducted daily over a period of two years and from the US Earth System Research Laboratory luminance sensor to investigate the impact of luminance on risk preferences, ambiguity preferences, choice consistency and dominance violations. We find that luminance levels affect all of these. Age and gender influence the strength of some of these effects.

Helping Others, Warming Yourself: Altruistic Behaviors Increase Warmth Feelings of the Ambient Environment

Altruistic behaviors typically improve the welfare of the recipient at the cost of the performer's resources and energy. Do altruistic performers obtain any positive internal reward from altruistic behaviors? We conducted six experiments to explore whether altruistic behaviors could increase performer's warmth perception of the ambient environment. The first three studies focused on crisis situations. A retrospective field study (Study 1, with Hurricane Sandy) and two laboratory studies (Studies 2a and 2b, with an earthquake scenario) found that people who helped others felt warmer of the ambient environment than people who did not. We extended to daily life situations and found that participants who performed helping behaviors in laboratory (either voluntarily in Study 3a or randomly assigned to in Study 3b) and passers-by who donated to a charity (Study 4) reported warmer perception of the ambient environment than those who did not. These findings suggested an immediate internal reward of altruism.

High prevalence of seasonal affective disorder among persons with severe visual impairment

BACKGROUND

Light severely affects the occurrence of seasonal affective disorder (SAD).

AIMS

To compare the prevalence of SAD in persons with severe visual impairment and persons with full sight, and in persons with severe visual impairment with or without light perception.

METHOD

This cross-sectional study assessed the Global Seasonality Score (GSS) and the prevalence of SAD among 2781 persons with visual impairment and 4099 persons with full sight using the Seasonal Pattern Assessment Questionnaire (SPAQ).

RESULTS

Respondents with visual impairment had significantly higher GSS and prevalence of SAD compared with full sight controls, P<0.001. Light perception respondents were more vulnerable to seasonal change than both full sight and no light perception respondents.

CONCLUSIONS

The study showed a highly significant association between visual impairment and SPAQ-defined SAD parameters, supporting the hypothesis that decreased retinal light input plays a role in the pathogenesis of SAD.

Time Out-of-Home and Cognitive, Physical, and Emotional Wellbeing of Older Adults: A Longitudinal Mixed Effects Model

Background

Time out-of-home has been linked with numerous health outcomes, including cognitive decline, poor physical ability and low emotional state. Comprehensive characterization of this important health metric would potentially enable objective monitoring of key health outcomes. The objective of this study is to determine the relationship between time out-of-home and cognitive status, physical ability and emotional state.

Methods and Findings

Participants included 85 independent older adults, age 65–96 years (M = 86.36; SD = 6.79) who lived alone, from the Intelligent Systems for Assessing Aging Changes (ISAAC) and the ORCATECH Life Laboratory cohorts. Factors hypothesized to affect time out-of-home were assessed on three different temporal levels: yearly (cognitive status, loneliness, clinical walking speed), weekly (pain and mood) or daily (time out-of-home, in-home walking speed, weather, and season). Subject characteristics including age, race, and gender were assessed at baseline. Total daily time out-of-home in hours was assessed objectively and unobtrusively for up to one year using an in-home activity sensor platform. A longitudinal tobit mixed effects regression model was used to relate daily time out-of-home to cognitive status, physical ability and emotional state. More hours spend outside the home was associated with better cognitive function as assessed using the Clinical Dementia Rating (CDR) Scale, where higher scores indicate lower cognitive function (β_CDR = -1.69, p<0.001). More hours outside the home was also associated with superior physical ability (β_Pain = -0.123, p<0.001) and improved emotional state (β_Lonely = -0.046, p<0.001; β_{Low mood} = -0.520, p<0.001). Weather, season, and weekday also affected the daily time out-of-home.

Conclusions

These results suggest that objective longitudinal monitoring of time out-of-home may enable unobtrusive assessment of cognitive, physical and emotional state. In addition, these results indicate that the factors affecting out-of-home behavior are complex, with factors such as living environment, weather and season significantly affecting time out-of-home. Studies investigating the relationship between time out-of-home and health outcomes may be optimized by taking into account the environment and life factors presented here.

The first observation of seasonal affective disorder symptoms in Rhesus macaque

Diurnal animals are a better model for seasonal affective disorder (SAD) than nocturnal ones. Previous work with diurnal rodents demonstrated that short photoperiod conditions brought about depression-like behavior. However, rodents are at a large phylogenetic distance from humans. In contrast, nonhuman primates are closely similar to humans, making them an excellent candidate for SAD model. This study made the first attempt to develop SAD in rhesus macaque (Macaca mulatta) and it was found that short photoperiod conditions could lead monkeys to display depressive-like huddling behavior, less spontaneous locomotion, as well as less reactive locomotion. In addition to these depression-related behavioral changes, the physiological abnormalities that occur in patients with SAD, such as weight loss, anhedonia and hypercortisolism, were also observed in those SAD monkeys. Moreover, antidepressant treatment could reverse all of the depression-related symptoms, including depressive-like huddling behavior, less spontaneous locomotion, less reactive locomotion, weight loss, anhedonia and hypercortisolism. For the first time, this study observed the SAD symptoms in rhesus macaque, which would provide an important platform for the understanding of the etiology of SAD as well as developing novel therapeutic interventions in the future.

Prevalence, behavioral manifestations and associated individual and climatic factors of seasonality in the Korean general population

BACKGROUNDS

Seasonality, an individual trait of seasonal variations in mood and behavior, has received clinical attention for its association with mood disorders. This study aimed to explore the prevalence, specific manifestation, and associated individual and climatic factors of seasonality in the non-elderly adult population.

METHODS

Five hundred fifty-two participants [male n=220; female n=332; mean age 34.92years, standard deviation (SD) 10.18] with no psychiatric history were recruited from the Seoul metropolitan area (37°33'58.87″N 126°58'40.63″E). Seasonality was evaluated using the Seasonal Pattern Assessment Questionnaire. Climatic variables used in analyses were averaged over recent 5years (from 2008 to 2013) on a monthly basis.

RESULTS

The mean global seasonality score (GSS) was 5.53 (SD 3.91), and 16.2% (n=89) of participants had seasonal affective disorder (SAD) or sub-SAD. The "feeling worst" month in most of the participants with significant seasonality were winter (41.6%) or summer (38.2%). Socio-demographic factors including age and sex were not related to the seasonality. Decreased sunlight amount and diurnal temperature range in a given and previous month, and increased humidity in a previous month showed significant associations with the percentage of participants with the worst mood. The most frequently reported symptom related to seasonality was 'changes in energy level'. Specific manifestations were not significantly different between the winter type and the summer type.

CONCLUSION

The summer and winter type seasonality in the non-clinical adult population did not differ in terms of behavioral manifestations. Decreased sunlight amount, diurnal temperature range, and increased humidity appeared to be major climatic factors associated with seasonality.

Geographical and climatic factors and depression risk in the SUN project

BACKGROUND

Depression incidence has been related with seasonal periodicity and climate. The aim of the study was to estimate the possible association between depression and specific meteorological factors, namely temperature, light and rain.

METHODS

In total, 13,938 participants from the SUN (Seguimiento Universidad de Navarra) cohort study were included in the analysis. Subjects were classified according to daily mean temperature, number of daylight hours and amount of rain, by year, at their geographical area of residence, data supplied by the Spanish Agency of Meteorology. Participants were considered as incident cases of depression whenever they reported a physician diagnosis of depression or the use of antidepressant medication in any of the follow-up questionnaires. Cox regression models were fit to assess the relationship between climatic and geographical factors and the incidence of depression.

RESULTS

Male subjects living in the south and centre areas of Spain showed a higher risk to develop depression compared with those living in the north area (hazard ratio = 1.6, 95% CI = 1.16-2.23 and hazard ratio = 1.41, 95% CI = 1.06-1.87, respectively). Moreover, among males, a direct association between the number of daily light hours and mean temperature and the risk of depression was also found. For men, living in rainy areas was associated with a lower risk of developing depression.

CONCLUSION

Our results suggest that climate-depression relationship is more complex than previously thought, and strongly different between men and women.

Two longterm studies of seasonal variation in depressive symptoms among community participants

BACKGROUND

There is evidence that seasonal variation in depressive symptoms is common in the population. However, research is limited by a reliance on longterm retrospective methods.

METHODS

Seasonal patterns were tested in two samples of community participants recruited in separate prospective studies in the Midwestern (n=556 males/females) and Pacific Northwestern (n=206 males) United States. Participants completed self-report measures of depressive symptoms 10-19 times from ages 14 to 36 years (n=8316 person observations). These data were compared with local meteorological conditions (e.g., solar radiation) recorded across the 2 weeks prior to each self-report.

RESULTS

In within-subjects analyses, participants' depressive symptoms and the probability of clinically significant symptoms varied with the time of year, as hypothesized (highest in the weeks of early Winter; lowest in early Fall). However, effect sizes were modest and were not explained by recent sunlight or other meteorological conditions.

LIMITATIONS

Samples were not nationally representative. Participants did not complete retrospective reports of seasonal depression or measures of current vegetative symptoms.

CONCLUSIONS

Neither time of the year nor recent seasonally linked meteorological conditions were powerful influences on depressive symptoms experienced by community populations in relevant geographic regions. Prior studies may have overestimated the prevalence and significance of seasonal variation in depressive symptoms for the general population.

Mental health and employment: The SAD story

This paper explores the relationship between health-related quality of life (HRQOL) measures and employment status in light of a constructed index related to Seasonal Affective Disorder that depends only on latitude and day of year. In models including demographic covariates and indicators for state, year, and quarter, more hours of darkness is associated with poorer HRQOL, which in turn is associated with a lower likelihood of employment. The relationships between the darkness index and HRQOL measures are stronger overall for women than for men. Inclusion of both the darkness index and the HRQOL measures in models of employment status determinants provides some evidence that the former operates through the latter in predicting a lower likelihood of employment. When specifying the darkness index as an instrument for HRQOL, each additional day of poor mental health per month leads to a 0.76 percentage point increase in the probability of unemployment among women.

Wind direction and mental health: a time-series analysis of weather influences in a patient with anxiety disorder

Time-series analysis was used to study the associations between daily weather variables and symptomatology in a man suffering from recurrent anxiety. Outcome measures were the patient's main symptoms: anxiety and energy. Wind direction appeared to be related to the patient's energy levels; these were significantly lower when the wind blew from the southeast. This effect could not be explained by other weather parameters. Decreases in energy in turn predicted increases in anxiety. The reverse effect was observed as well, with increases in anxiety predicting decreases in energy, indicating a positive feedback loop.

State and regional prevalence of sleep disturbance and daytime fatigue

STUDY OBJECTIVES

Social and demographic influences are important for sleep attainment. Geographic location has not been previously explored.

METHODS

Data from the 2006 Behavioral Risk Factor Surveillance System (BRFSS) were used (N = 157,319). Participants answered a question on Sleep Disturbance and Daytime Fatigue. Thirty-six states/regions provided data on these items. Prevalence estimates were adjusted for age, sex, ethnoracial group, education, income, employment, general health, healthcare access, and depression. Chi-squared tests were conducted across states and census regions, and pseudo-R(2) values were computed for the effect of state, relative to other predictors. To evaluate potential mediators of census region differences, an analysis of p value change associated with specific covariates and covariate groups was undertaken.

RESULTS

Adjusted prevalence rates of Sleep Disturbance differed across states/regions overall (χ(2) = 412.3, p < 0.0001), as well as separately for men (χ(2) = 139.5, p < 0.0001) and women (χ(2) = 350.0, p < 0.0001), as did rates of Daytime Fatigue overall (χ(2) = 245.7, p < 0.0001), and separately for men (χ(2) = 117.5, p < 0.0001) and women (χ(2) = 181.2, p < 0.0001). Analysis of pseudo-R(2) values revealed that despite these significant findings, state differences were an overall weak predictor, representing 1.30% to 1.73% of the magnitude of the effect of the best predictor (mental health). When Census regions were compared, significant differences were found for Sleep Disturbance (p = 0.002), but after adjustment for covariates, these were no longer significant. Differences existed for Daytime Fatigue in adjusted analyses overall (p < 0.0001), with the West reporting the fewest complaints and the South reporting the most.

CONCLUSIONS

These results demonstrate that reports of sleep related complaints vary across states, independent (at least partially) of factors that influence circadian rhythms (e.g., latitude).

Study protocol: a cross-sectional survey of seasonal affective disorder in Danish populations with and without severe visual impairments

INTRODUCTION

People with seasonal affective disorder (SAD) experience recurrent seasonal fluctuations in energy, mood and appetite. Retinal light exposure is suggested to play an important role in the pathogenesis and treatment of SAD. The aim of the study is to determine the prevalence of SAD in persons with severe visual impairments or blindness and to compare the results to a control group without visual impairments. Moreover, the authors wish to investigate whether SAD is correlated to the degree of impairment or to the diagnosis.

METHODS AND ANALYSIS

2781 persons with visual impairments ranging from total blindness to Snellen visual acuity 6/60 receive information letter and questionnaire by post. Completed questionnaires can be returned by post, email or telephone. For each respondent, all eye-related diagnoses will be obtained from national registries. Normally sighted and demographically matched control respondents will be contacted in a similar manner the subsequent winter season. The Seasonal Pattern Assessment Questionnaire rates seasonal variation within the six items: sleep, appetite, social activity, mood, energy and body weight. The Seasonal Pattern Assessment Questionnaire yields a Global Seasonal Score and a prevalence of SAD. Outcomes from the two groups will be compared. Moreover, outcomes from subgroups of the visually impaired population will be compared.

ETHICS AND DISSEMINATION

The study is approved by the Danish Data Protection Agency. Results will be published in a relevant scientific journal and be communicated to respondents and relevant institutions through cooperation with the Danish Association of the Blind.

Surface facial electromyography, skin conductance, and self-reported emotional responses to light- and season-relevant stimuli in seasonal affective disorder

BACKGROUND

Learned associations between depressive behavior and environmental stimuli signaling low light availability and winter season may play a role in seasonal affective disorder (SAD). The purpose of this study was to determine whether light and season environmental cues elicit emotional responses that are distinct in individuals with SAD.

METHODS

Twenty-four currently depressed SAD participants were compared to 24 demographically-matched controls with no depression history on emotional responses to outdoor scenes captured under two light intensity (i.e., clear, sunny vs. overcast sky) and three season (i.e., summer with green leaves, fall with autumn foliage, and winter with bare trees) conditions. Emotion measures included surface facial electromyography (EMG) activity in the corrugator supercilii and zygomaticus major muscle regions, skin conductance, and self-reported mood state on the Profile of Mood States Depression-Dejection Subscale.

RESULTS

Light intensity was a more salient cue than season in determining emotional reactions among SAD participants. Relative to controls, SAD participants displayed more corrugator activity, more frequent significant skin conductance responses (SCR), greater SCR magnitude, and more self-reported depressed mood in response to overcast stimuli and less corrugator activity, lower SCR magnitude, and less self-reported depressed mood in response to sunny stimuli.

LIMITATIONS

Study limitations include the single, as opposed to repeated, assessment and the lack of a nonseasonal depression group.

CONCLUSIONS

These findings suggest that extreme emotional reactivity to light-relevant stimuli may be a correlate of winter depression; and future work should examine its potential onset or maintenance significance.

This is Your Portfolio on Winter

This study found that people who suffer from seasonal affective disorder (SAD) displayed financial risk aversion that varied across the seasons as a function of seasonally changing affect. The SAD-sufferers had significantly stronger preferences for safe choices during the winter than non-SAD-sufferers, and they did not differ from non-SAD-sufferers during the summer. The effect of SAD on risk aversion in the winter was mediated by depression.

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.

Seasonal patterns of initiating antidepressant therapy in general practice in the Netherlands during 2002-2007

BACKGROUND

Studies on seasonality in antidepressant prescribing showed prescribing peaks during autumn and winter. Since then, new antidepressants have become available and indications have broadened, possibly contributing to a change in prescribing practices. This study investigates seasonal patterns of initiating antidepressant use in general practice during 2002-2007 in the Netherlands.

METHOD

Data were obtained from the Netherlands Information Network of General Practice. The study population was composed of adult patients initiating antidepressant use from 21 December 2001 to 20 December 2007, with no antidepressant use during at least two years prior to initiation. Seasonal distribution of initiating antidepressant use was investigated for the four seasons. The difference in frequency of initiating use between the seasons, normalized for general practice contacts, was tested using Chi-square testing.

RESULTS

The majority of the study population (N=16,289) was female (64.0%) with a mean age (standard deviation (SD)) of 50.5 (18.0) years. Significant seasonal variation (p<0.01) was found in initiation of antidepressant use, with about 5-35% more patients initiating use during winter than summer. Significant (p<0.01) seasonality of initiating antidepressant use was seen in all patient groups, except within age groups 18-30 years and >60 years.

LIMITATIONS

Our study investigated only general practitioner prescribing thus additional prescriptions from psychiatrists are missed.

CONCLUSIONS

The seasonal influence on initiation of antidepressant drug use has not changed with the introduction of the newer antidepressants and is in line with seasonality of depression onset, with most patients initiating use during the winter and fewest during the summer.

Climatic relationships with specific clinical subtypes of depression

Studies on the relationship between climate and unipolar depression rates have yielded mixed results, which could be attributed to the inclusion of heterogeneous clinical samples and the use of admission rather than onset dates. This study aimed to overcome these methodological issues. During an 8-year timeframe, onset rates of unipolar depressive episodes requiring hospitalization from individuals living up to 15 km from a selected meteorological station were stratified by clinical subtypes and modeled as Autoregressive Integrated Moving Average (ARIMA) functions of orthogonal climatic factors obtained by Principal Components Analysis (PCA). For comparison purposes, onset rates stratified by demographic factors and by diagnosis of Seasonal Affective Disorder (SAD) and admission rates were also modeled. The main findings were a negative 1-month delayed relationship between onset rates of episodes with melancholic features and a climatic factor mainly composed of ambient temperature/sunlight, and a negative 1-month delayed relationship between onset rates of episodes with psychotic features and a climatic factor mainly composed of barometric pressure. Results of this study support a climatic-rather than seasonal-influence in specific subtypes of depression. If replicated, they may have nosological and therapeutic implications.

The prevalence of seasonal affective disorder (SAD) in Greenland is related to latitude

The aim of this study was to determine the prevalence of seasonal affective disorder (SAD) in Greenlanders and Danes living at four different latitudes in Greenland. A Seasonal Pattern Assessment Questionnaire (SPAQ) was mailed to 6021 men and women between the ages of 18 and 59 years living in four different municipalities in Greenland. The recipients were randomly selected from the National Population Register. Approximately 9% of the respondents met the criteria for SAD, and the incidence of SAD varied between a southern municipality and three northern municipalities. The prevalence of SAD was particularly high in northern municipalities. No significant difference was found in the prevalence of SAD between Greenlanders and Danes. The results are comparable with other population studies that have reported a high prevalence of SAD in arctic areas. The clinical implications of our findings and the possibilities for introducing light therapy should be assessed in future studies.

Seasonal vegetative and affective symptoms in the Finnish general population: testing the dual vulnerability and latitude effect hypotheses

BACKGROUND

Prior studies identified a seasonal pattern in symptoms of depression in clinical and population-based samples. The aims of our study were to estimate the prevalence rates of routine seasonal variations in mood and behavior and of current depressive symptoms in the Finnish general population over 30 years, and to find differences, if any, between the northern and southern regions of residence.

METHODS

5749 participants aged 30-97 (3156 women and 2593 men) were interviewed face to face and attended a health status examination. We included the modified Seasonal Pattern Assessment Questionnaire and the modified Beck Depression Inventory (BDI) for the analysis.

RESULTS

85% of the sample, representative of a general population, had seasonal variations in mood and behavior; 9% of the sample scored high on both scales, thus having the routine seasonal variations together with a current self-report of winter depression. Scoring high on the former scale yielded the odds ratio of 3.12 for scoring high on the BDI. Neither the global seasonality score nor the BDI sum score was associated with latitude. No significant differences in affective symptoms were found by the latitude. The seasonal variation in sleep duration (P<0.001) was more prevalent in the northern regions.

LIMITATIONS

The seasonal variations were assessed with a self-report only.

CONCLUSIONS

A seasonal pattern in mood and behaviors was detected in a general population. Implications of our findings include the assessment of the seasonal variations as a risk factor of depressive illness.

Cold and Lonely

Metaphors such as icy stare depict social exclusion using cold-related concepts; they are not to be taken literally and certainly do not imply reduced temperature. Two experiments, however, revealed that social exclusion literally feels cold. Experiment 1 found that participants who recalled a social exclusion experience gave lower estimates of room temperature than did participants who recalled an inclusion experience. In Experiment 2, social exclusion was directly induced through an on-line virtual interaction, and participants who were excluded reported greater desire for warm food and drink than did participants who were included. These findings are consistent with the embodied view of cognition and support the notion that social perception involves physical and perceptual content. The psychological experience of coldness not only aids understanding of social interaction, but also is an integral part of the experience of social exclusion.

Light exposure is related to social and emotional functioning and to quality of life in older women

While there are data supporting the use of light in clinical populations, there has been less investigation of relationships among light and psychological variables in non-clinical samples. Subjects were 459 ethnically diverse women (mean age 67.68) recruited as part of the Women's Health Initiative. Light exposure and sleep were measured with an Actillume wrist actigraph. Subjects completed questionnaires, investigating Social Support, Social Functioning, Social Strain, Quality of Life, Satisfaction with Life, Emotional Well-being, Optimism, Negative Emotional Expressiveness, and Role Limitation Due to Emotional Problems. Significant partial correlations (controlling for age, education and ethnicity) were found between mesor light exposure and Social Functioning, Quality of Life, Satisfaction with Life, and Emotional Well-Being. Quality of Life and Satisfaction with Life were also found to be significantly correlated with morning light. The most parsimonious model to account for the variance shared between mesor light and the predictors included only Quality of Life. The variance shared between mesor light exposure and social and emotional functioning could be subsumed under the variance shared between mesor light exposure and Quality of Life. Increased light exposure is related to improved quality of life and social and emotional functioning.

Seasonal changes in clinical status in bipolar disorder: a prospective study in 1000 STEP-BD patients

OBJECTIVE

To investigate seasonal and regional effects on bipolar I and II patients.

METHOD

The Systematic Treatment Enhancement Program for Bipolar Disorder (STEP-BD) patients were prospectively examined for monthly change in prevalence rates of depressed and recovered clinical status over the year. General Estimating Equation modeling was used to assess the effect of season on prevalence rates. Additionally, patients were stratified by bipolar subtype and by region.

RESULTS

A significantly higher prevalence rate of depression is observed in the northern sites, a significant prevalence by month effect is found only in the bipolar II patients.

CONCLUSION

The prevalence of depression is greater in patients from the northern vs. southern STEP-BD sites. Seasonal peak prevalence rates of depression differ by region. Bipolar II patients were more ill year-round and demonstrated greater monthly fluctuation in prevalence rates of being ill than did bipolar I patients. We conclude that seasonal effects upon bipolar patients vary by region and bipolar subtype.