Global Seasonality Score Research Articles

Seasonal variation in mood among individuals with and without bipolar disorder

IntroductionBipolar disorder is a disorder characterized by cyclic changes in mood, yet limited research has explored longitudinal patterns of seasonality on mood symptoms in this population. This study aimed to examine longitudinal mood symptoms in individuals with bipolar type I and II, and healthy controls to determine if seasonal patterns were present and to validate the Global Seasonality Score as a measure of seasonality. MethodsParticipants from the Prechter Longitudinal Study of Bipolar Disorder were included. Seasonal variations in mood were determined from the Patient Health Questionnaire, Altman Self-Rating Mania scale, and the Seasonal Pattern Assessment Questionnaire. Mixed effects models were utilized to examine the effects of season and diagnostic group on patterns of mood over time. ResultsAll groups exhibited significant seasonal effects on mood symptoms, with evidence of decreased depressive symptoms and increased mania symptoms in longer daylight months. The Global Seasonality Score showed significant differences between diagnostic groups, with bipolar I and II groups demonstrating higher seasonality than healthy controls. High seasonality was associated with greater variance in mood symptoms. ConclusionThe present study found evidence of seasonal patterns in mood symptoms in individuals with bipolar type I and II. These results highlight the need for consideration of seasonality in assessment and treatment in bipolar disorder and suggest that interventions such as light therapy during seasons of heightened risk could be beneficial. The validation of the Global Seasonality Score as a reliable measure further underscores the benefit of utilizing self-report measures to identify periods of vulnerability.

571. Fertility is Negatively Associated With the Global Seasonality Score in Old Order Amish Women

571. Fertility is Negatively Associated With the Global Seasonality Score in Old Order Amish Women

No Association Between NPAS2 rs6425296 Polymorphism and Seasonality, Diurnal Preference in Koreans

Objective: Seasonal variations in mood and behavior and diurnal preference are associated with several genes that regulate circadian rhythms. In this study, we investigated the association of the <i>NPAS2</i> rs6725296 polymorphism with seasonality and diurnal preference.Methods: A total of 510 healthy subjects were genotyped for the <i>NPAS2</i> rs6725296 polymorphism and completed self-report questionnaires on seasonality and diurnal preferences. Seasonality was evaluated using the seasonal pattern assessment questionnaire, and diurnal preference was evaluated using the Composite Scale of Morningness (CSM). We assessed the association of genotype and allele carrier status with the total and subscale scores of global seasonality scores (GSS) for seasonality and the total and subscale scores of CSM for diurnal preference.Results: No significant associations were found between the <i>NPAS2</i> rs6725296 genotype and the allele carrier status and the GSS and CSM scores.Conclusion: The results of this study suggest that the <i>NPAS2</i> rs6725296 polymorphism may not contribute to seasonality and diurnal preference in healthy Koreans. More studies with a larger number of subjects, inclusion of different ethnic groups, and complementation with objective measurements of seasonality and diurnal preference are necessary to evaluate the influence of genetics on seasonality and diurnal preference.

Vision-Related Quality of Life and Seasonal Affective Disorder in Patients with Glaucoma and Macular Degeneration.

Seasonal affective disorder (SAD) is characterized by depressive episodes related to changes in the seasons. Patients with severe vision loss are at an increased risk of SAD. This study seeks to determine the extent to which patients with moderate vision loss report symptoms of SAD. In this cross-sectional, comparative case series, the Seasonal Pattern Assessment Questionnaire (SPAQ) and the National Eye Institute Visual Function Questionnaire (VFQ-39) were used to screen 111 patients with age-related macular degeneration (AMD) and/or primary open-angle glaucoma (POAG). A multiple regression analysis was performed to create a predictive model for SAD based on the Global Seasonality Score (GSS) using the VFQ-39. Subjects who reported symptoms of SAD (GSS > 8) had lower vision-related quality of life (composite score: 57.2 versus 73.2, p < 0.001). Exploratory factor analysis revealed that the items on the VFQ-39 split into two distinct dimensions that together accounted for 63.2% of the total variance in the GSS. One group of questions addressed vision-related problems; the other group comprised questions related to the quality of life. Whereas this model successfully identified patients with vision loss at risk of SAD, a model restricted to the questions available on the shorter, widely used VFQ-25 instrument did not reliably identify patients at risk of SAD.

Seasonality contributes to depressive, anxiety and alcohol use disorders in the Finnish general adult population

BackgroundEarlier evidence suggests that the seasonal changes in mood and behavior are associated with mental disorders, especially with mood disorders. However, the extent of these associations has not been analyzed by using large samples of the general population. MethodsA random sample of adults, aged 29 to 97 years and representative of the general population living in Finland, attended a nationwide health examination survey. Mental disorders were assessed with the Munich version of the Composite International Diagnostic Interview (M-CIDI, n = 4554). Of them, the seasonal variations in mood and behavior (seasonality) were assessed with the six items of the Global Seasonality Score (GSS, n = 4004) as well as with the experienced problem due to these variations. ResultsAfter adjusting for age, gender, level of education, and region of residence, the GSS was associated with depressive, anxiety and alcohol use disorders (all p < 0.001). Of the GSS items, mood was associated with depressive disorders (p < 0.001), anxiety disorders (p = 0.003) and alcohol use disorders (p = 0.008), whereas appetite was associated only with depressive disorders (p = 0.012), and energy level only with anxiety disorders (p = 0.025). LimitationsThis cross-sectional study was based on self-reported data on the seasonal pattern. ConclusionsSeasonality had significant associations with depressive, anxiety and alcohol use disorders among the general adult population. This needs attention in clinical practice.

Seasonal changes in mood and behavior contribute to suicidality and worthlessness in a population-based study

Limited evidence suggests that the seasonal changes in mood and behavior may associate with suicidality and the feelings of worthlessness, but these associations have not been analyzed in large population-based data. A random sample of adults (n = 4069), representative of the general population living in Finland, attended a nationwide health examination survey. Seasonal variations (seasonality) in mood and behavior were analyzed with the six items of global seasonality score (GSS) and the experienced problem due to these variations. Their impact on suicidality as well as on the feelings of worthlessness were analyzed using logistic regression models. After adjusting for age and gender, the GSS, each of its six items and the experienced problem due to the seasonal variations in mood and behavior all showed separately a significant association with suicidality as well as with worthlessness. After further adjustment for the education level and region of residence, the GSS, its mood item and the experienced problem remained significantly associated with both suicidality and worthlessness. Seasonal variations in mood and behavior have a significant association with both suicidality and worthlessness.

Incidence rate and clinical characteristics of seasonal affective disorders in senior medical students

Aim. To study the incidence rate, clinical features, and prognosis of seasonal affective disorder (SAD) in senior (6th-year) medical students.Materials and methods. SAD screening using the Seasonal Pattern Assessment Questionnaire (SPAQ, 1987) included 119 undergraduate medical students. 78 students were females (65.5%) and 41 – males (34.5%) (p = 0.001). The average age of women was 23 (22; 23) years, the average age of men – 23 (22; 24) years. Statistical processing was performed using the Mann – Whitney U-test, Pearson’s χ2 test, and Spearman’s rank correlation coefficient (rs).Results. The data on the prevalence of affective disorders with a seasonal pattern in medical students were obtained: SAD – 9.2%, sub-SAD – 13.5%, psychological undulation of season perception (PUSP) – 16.8%. The number of students who did not exhibit seasonal undulation of the six main characteristics recorded by the SPAQ was 72 (60.5%) (p = 0.001). There were statistically significant differences in the higher median Global Seasonality Score of the SPAQ for SAD compared with PUSP, both with and without account of the gender factor (p = 0.001). The use of a binary logistic regression model made it possible to identify groups of students with or without SAD according to the SPAQ. The data obtained determined the contribution of the following factors: gender, seasonality, body weight, and the number of sleep hours per day in spring.Conclusion. The study made it possible to obtain a logistic regression model that allowed to predict the greatest likelihood of developing SAD.

Validity and Usage of the Seasonal Pattern Assessment Questionnaire (SPAQ) in a French Population of Patients with Depression, Bipolar Disorders and Controls.

The Seasonal Pattern Assessment Questionnaire (SPAQ), by Rosenthal et al. (1984), is by far the most used questionnaire to evaluate seasonal effects on mood and behavior. It includes a general seasonality score (GSS), composed of 6 items, from which cutoffs have been established to screen for seasonal affective disorder (SAD). However, it has never been validated in French and associations with circadian rhythm and symptoms of depression and bipolarity remain unclear. In this study, including 165 subjects (95 controls and 70 patients with depression or bipolar disorder), we confirmed the validity of the French version of the SPAQ, with a two-factor structure (a psychological factor: energy, mood, social activity and sleep length; and a food factor: weight and appetite) and a good fit was observed by all indicators. Mood and social activity dimensions were significantly affected by seasons in the depressed/bipolar group and a stronger global seasonality score (GSS) was associated with more severe phenotypes of depression and mania. Subjects meeting SAD and subsyndromal-SAD criteria also showed a delayed circadian rhythm compared to controls. Simple tools, such as the SPAQ, can aid the identification of significant seasonal changes and have direct implications on therapeutics including the use of bright light therapy in order to enhance personalized treatments, but also to prevent adverse seasonal effects.

Bipolar II disorder has the highest prevalence of seasonal affective disorder in early-onset mood disorders: Results from a prospective observational cohort study.

Many mood disorder patients experience seasonal changes in varying degrees. Studies on seasonality have shown that bipolar disorder has a higher prevalence rate in such patients; however, there is limited research on seasonality in early-onset mood disorder patients. This study estimated the prevalence of seasonality in early-onset mood disorder patients, and examined the association between seasonality and mood disorders. Early-onset mood disorder patients (n = 378; 138 major depressive disorder; 101 bipolar I disorder; 139 bipolar II disorder) of the Mood Disorder Cohort Research Consortium and healthy control subjects (n = 235) were assessed for seasonality with Seasonality Pattern Assessment Questionnaire (SPAQ). A higher global seasonality score, an overall seasonal impairment score, and the prevalence of seasonal affective disorder (SAD) and subsyndromal SAD showed that mood disorder subjects had higher seasonality than the healthy subjects. The former subject group had a significantly higher mean overall seasonal impairment score than the healthy subjects (p < .001); in particular, bipolar II disorder subjects had the highest prevalence of SAD, and the diagnosis of bipolar II disorder had significantly higher odds ratios for SAD when compared to major depression and bipolar I disorder (p < .05). Early-onset mood disorders, especially bipolar II disorder, were associated with high seasonality. A thorough assessment of seasonality in early-onset mood disorders may be warranted for more personalized treatment and proactive prevention of mood episodes.

Night Eating Syndrome, circadian rhythms and seasonality: a study in a population of Italian university students.

The aim of this research was to assess the prevalence of Night Eating Syndrome (NES) in a university student population and to clear up the relationship between NES, depression and chronotype. The relation between NES and seasonality was also investigated. The data were collected from a sample of 1136 students of the L'Aquila University, Italy. All subjects were invited to answer to the Sociodemographic Information Form and to take a self-report battery composed by four questionnaires: the Night Eating Questionnaire (NEQ), the Morningness Eveningness Questionnaire (MEQ), the Seasonal Pattern Assessment Questionnaire (SPAQ) and the Beck Depression Inventory (BDI). The 5.3% of our population (60 subjects) reached the criteria for NES. The distribution of chronotypes in the sample was: Morning Type 15.3%, Intermediate 64.3% and Evening Type 20.4%. The 36.7% of the participants reaching the criteria for NES, obtained low scores on the MEQ. The data indicated that NEQ and MEQ scores are significantly inversely correlated (r=-.22; p<.01, two-tailed test). The 3.6% of our population (41 subjects) reached the criteria for Seasonal Affective Disorder (SAD) and 10.7% for subclinical SAD (121 subjects). Furthermore, the 11.7% of subjects with NES presented SAD and the 5% presented Subclinical SAD. The data demonstrated that NES and Global Seasonality Score (GSS) are significantly associated (r=.22; p<0.01, two-tailed test). The main finding of this study is the strong relation between NES and eveningness dimension. Our results help to clear up the literature debate about the role of eveningness dimension in the night eating, suggesting that subjects with NES present a circadian delay, not only in the food intake, but in the entire functioning. At the best of one knowledge this study is the first one to examine the relationship between NES and seasonality. This research found preliminary evidence that, similarly to the findings of previous studies in subjects with Bulimia Nervosa (BN) and Binge Eating Disorder (BED), night eating symptoms may vary significantly across the seasons; subjects with NES experience seasonal variation in their mood and in their eating patterns.

Seasonal affective disorder and seasonal changes in weight and sleep duration are inversely associated with plasma adiponectin levels

Overlapping pathways between mood and metabolic regulation have increasingly been reported. Although impaired regulation of adiponectin, a major metabolism-regulating hormone, has been implicated in major depressive disorder, its role in seasonal changes in mood and seasonal affective disorder-winter type (SAD), a disorder characterized by onset of mood impairment and metabolic dysregulation (e.g., carbohydrate craving and weight gain) in fall/winter and spontaneous alleviation in spring/summer, has not been previously studied. We studied a convenience sample of 636 Old Order Amish (mean (± SD), 53.6 (±14.8) years; 50.1% males), a population with self-imposed restriction on network electric light at home, and low prevalence of total SAD (t-SAD = syndromal + subsyndromal). We calculated the global seasonality score (GSS), estimated SAD and subsyndromal-SAD after obtaining Seasonal Pattern Assessment Questionnaires (SPAQs), and measured overnight fasting plasma adiponectin levels. We then tested associations between plasma adiponectin levels and GSS, t-SAD, winter-summer difference in self-reported sleep duration, and self-reported seasonal weight change, by using analysis of co-variance (ANCOVA) and linear regression analysis after adjusting for age, gender, and BMI. Participants with t-SAD (N = 14; 2.2%) had significantly lower plasma adiponectin levels (mean ± SEM, 8.76 ± 1.56 μg/mL) than those without t-SAD (mean ± SEM, 11.93 ± 0.22 μg/mL) (p = 0.035). In addition, there was significant negative association between adiponectin levels and winter-summer difference in self-reported sleep duration (p = 0.025) and between adiponectin levels and self-reported seasonal change in weight (p = 0.006). There was no significant association between GSS and adiponectin levels (p = 0.88). To our knowledge, this is the first study testing the association of SAD with adiponectin levels. Replication and extension of our findings longitudinally and, then, interventionally, may implicate low adiponectin as a novel target for therapeutic intervention in SAD.

Association of G-Protein β3 Subunit C825T Polymorphism with Seasonal Variations in Mood and Behavior.

Objective Seasonal affective disorder and seasonal changes in mood and behavior are associated with several genes that regulate circadian rhythms. In this study, we investigated the relationship between the C825T polymorphism of the G-protein β3 subunit and seasonal variations in mood and behavior in a young healthy Korean population. Methods A total of 507 young Korean participants were recruited through a newspaper advertisement, and their seasonality was evaluated by the Korean version of the Seasonal Pattern Assessment Questionnaire to assess the global seasonality score (GSS). We analyzed the CC, CT, and TT genotypes and their association with the GSS score and subscales. Results T allele carriers of the GNB3 C825T polymorphism were more likely to score higher on body weight and GSS. In the female group, the T allele carriers obtained significantly high total GSS and its subscale scores for mood, body weight, energy level, and appetite; however, differences in genotypes and allele carriers were also observed in the male participants. Conclusion These results suggested that GNB3 C825T polymorphism plays a role in seasonal variations in mood, body weight, energy level, and appetite in a Korean population, particularly in females.

Eye disorder differentiates seasonality outcomes in persons with severe visual impairment

BackgroundLight plays a crucial role in both the pathogenesis and treatment of seasonal affective disorder (SAD). Consequently decreased retinal sensitivity to light has been suggested to be a risk factor for SAD. In a population of persons with severe visual impairment we recently found a highly increased prevalence of SAD. We now aimed to identify eye disorders or anatomical locations with specific association to seasonality. MethodsIn 912 cases (33%) from our prior seasonal pattern assessment questionnaire (SPAQ) screening study, we retrieved eye diagnoses from the Danish National Patient Registry and analyzed for specific eye disorders or anatomical locations that significantly differentiated SPAQ outcomes (global seasonality score, (GSS) and SPAQ-SAD prevalence). ResultsPersons with early life eye disorders (congenital conditions or retinopathy of prematurity) reported less symptoms of SAD (median GSS 4.5) than persons with acquired eye disorders (median GSS 5.0, p=0.005). Persons with macular degenerative disorders (MD) had highly increased seasonality outcomes (hazard ratio 2.23, p=0.002, median GSS 5 vs. 8, p=0.01). Limitationsthe study is a cross-sectional study based on a self-report questionnaire. Register data may be incomplete. ConclusionsMD is significantly associated to high-level seasonality and SAD prevalence. Early life eye disorder is associated to slightly lower seasonality compared to acquired eye disorder. Longitudinal studies are needed to assess causality.

Circadian Rhythm and Sleep During Prolonged Antarctic Residence at Chinese Zhongshan Station

Residence at Zhongshan Station (69°22'24″S, 76°22'40″E) for over 1 year exposes winter-over members to marked changes of light-dark cycle, ranging from the constant daylight of polar days to the constant darkness of polar nights, in addition to geographic and social isolation. This extreme photoperiodic environment may increase the risk of sleep disturbances and circadian desynchrony. The aim of this study was to investigate the circadian rhythm and sleep phase of Chinese winter-over expeditioners at Zhongshan Station. This study was conducted on 17 healthy male participants before departure from Shanghai and during residence at Zhongshan Station for 1 year (before winter, mid-winter, and end of winter). Sequential urine samples over 48 hours were obtained, 6-sulphatoxymelatonin in urine was assessed, and the circadian rhythm was analyzed by a cosine curve-fitting method. Participants' sleep parameters were obtained from wrist actigraphy and sleep logs. Morningness-Eveningness Questionnaire and Seasonal Pattern Assessment Questionnaire were completed. The acrophase of 6-sulphatoxymelatonin rhythm, sleep onset, sleep offset, and mid-sleep time were delayed significantly (P < .05) in Antarctica relative to departure values. The subjects had greater eveningness preference (P < .05) in mid-winter in Antarctica. The Global Seasonality Score and the prevalence of subsyndromal seasonal affective disorder increased (P < .05) during winter. Our results indicate that during polar nights Chinese expeditioners experienced the following problems: delayed circadian rhythm and sleep phase, later chronotype, and incidence of subsyndromal seasonal affective disorder. An appropriate combination of artificial bright light during dark winter months and a strict social schedule are recommended in a winter-over station in Antarctica.

Morningness-eveningness and seasonality

The study aimed to elucidate previously observed associations between morningness–eveningness and seasonality by analysing their distinct aspects separately: morning affect (MA) and time-of-day preference, different seasonal types and patterns (winter, summer, etc.), the degree of seasonality and perceived negative impact of seasonality. Students from Warsaw (N = 522) completed the Seasonal Pattern Assessment Questionnaire and the Composite Scale of Morningness. Winter seasonality was related to lower MA, but unrelated to time-of-day preference. Global seasonality score was negatively associated with MA in winter seasonality, but not in other seasonality patterns, and unrelated to time-of-day preference. These associations remained significant after controlling for sex, age and season of assessment. It is concluded that winter seasonality is related to low MA, but not to time-of-day preference. The above results indicate that MA can be considered as an all year round indicator of proneness to winter seasonality and eventually to seasonal affective disorder. The results also suggest that MA and time-of-day preference should be analysed separately in future research on morningness–eveningness.

Seasonal mood changes in patients with obsessive–compulsive disorder

Obsessive–compulsive disorder (OCD) is frequently associated with mood disorders. However, to date, the co-occurrence of OCD with seasonal affective disorder (SAD) has not been investigated. We have aimed to estimate the prevalence of seasonal mood changes in patients with OCD and explore the contribution of seasonality in mood to the severity of OCD. The Seasonal Pattern Assessment Questionnaire (SPAQ), the Yale-Brown Obsession and Compulsion Scale (Y-BOCS), the Hamilton Depression Rating Scale-17 Items (HDRS-17), and the Beck Anxiety Inventory (BAI) were administered to patients with OCD (n=104) and controls (n=125). The degree of seasonality was measured by the Global Seasonality Score (GSS) calculated from the SPAQ. SAD and subsyndromal seasonal affective disorder (S-SAD) were significantly more prevalent in patients with OCD (53%, n=55) than controls (25%, n=31). When patients were assessed in the season in which SAD occurs, depression and compulsions (but not obsessions, OCD or anxiety) were more severe than those assessed in a season during which SAD does not occur. SAD frequently co-occurs with OCD and, given this co-occurrence, depression symptoms in some patients with OCD might be expected to vary on a seasonal basis.

Seasonal affective disorder associate with common chronic diseases and symptoms in a population-based study

BackgroundSeasonal affective disorder (SAD) is a recurrent mood disorder with 22%–42% of the patients experiencing symptoms even after 5–11 years after diagnosis, and 33%–44% developing non-seasonal symptoms. The purpose of this study was to assess how seasonality is associated with some of the most common non-communicable diseases in the general Finnish population.MethodsThe global seasonality score (GSS) and the experiences of problems due to the seasonal variations from FINNRISK 2012 dataset were used to measure the seasonality in 4689 Finns aged 25–74 years living in five geographical regions in Finland, and assess their association with common non-communicable diseases (NCDs). The regression models and odds ratios were adopted to analyze the associations adjusted for covariates.ResultsThe prevalence of SAD in the Finnish general population is 21%. Seventy percent of the participants had seasonal variations in sleep duration, social activity, mood and energy level, while 40% had seasonal variations is weight and appetite. Angina pectoris and depression were significantly associated with seasonality, including seasonal variations in sleep duration, mood, weight, appetite, social activity and energy level. Depression was significantly associated with the increased odds for experiencing a problem due to the seasonal variations (OR = 4.851, P &lt; 0.0001) and SAD symptoms (OR = 4.075, P &lt; 0.0001), and with the GSS (P &lt; 0.0001).ConclusionOur data suggest that seasonality is associated with depression and angina pectoris. The co-occurrence of the seasonal variations in mood and behavior with common NCDs warrants the need for future research to have insights into the etiology and potentially shared pathways and mechanisms of action.Disclosure of interestThe authors have not supplied their declaration of competing interest.

Seasonal variations in mood and behavior associate with common chronic diseases and symptoms in a population-based study

The purpose of this study was to assess how seasonality is associated with some of the most common non-communicable diseases (NCDs) in the general Finnish population. The global seasonality score (GSS) was used to measure the magnitude of seasonality in 4689 participants, in addition to which they reported the extent to which the seasonal variations in mood and behavior were experienced as a problem. Regression models and the odds ratios were adopted to analyze the associations adjusted for a range of covariates. Seventy percent of the participants had seasonal variations in sleep duration, social activity, mood, or energy level, and forty percent those in weight and appetite. Angina pectoris and depression were significantly associated with seasonality throughout the analysis. Hypertension, high cholesterol levels, diabetes, other (than rheumatoid) joint diseases and other (than depressive) psychological illnesses were significantly associated with experiencing a problem due to the seasonal variations, with an increase in the GSS, and with seasonal affective disorder and its subsyndromal form. The co-occurrence of the seasonal variations in mood and behavior with certain common NCDs warrants future research to have insights into the etiology and potentially shared pathways and mechanisms of action.

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

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

Seasonality shows evidence for polygenic architecture and genetic correlation with schizophrenia and bipolar disorder.

To test common genetic variants for association with seasonality (seasonal changes in mood and behavior) and to investigate whether there are shared genetic risk factors between psychiatric disorders and seasonality. Genome-wide association studies (GWASs) were conducted in Australian (between 1988 and 1990 and between 2010 and 2013) and Amish (between May 2010 and December 2011) samples in whom the Seasonal Pattern Assessment Questionnaire (SPAQ) had been administered, and the results were meta-analyzed in a total sample of 4,156 individuals. Genetic risk scores based on results from prior large GWAS studies of bipolar disorder, major depressive disorder (MDD), and schizophrenia were calculated to test for overlap in risk between psychiatric disorders and seasonality. The most significant association was with rs11825064 (P = 1.7 × 10⁻⁶, β = 0.64, standard error = 0.13), an intergenic single nucleotide polymorphism (SNP) found on chromosome 11. The evidence for overlap in risk factors was strongest for schizophrenia and seasonality, with the schizophrenia genetic profile scores explaining 3% of the variance in log-transformed global seasonality scores. Bipolar disorder genetic profile scores were also associated with seasonality, although at much weaker levels (minimum P value = 3.4 × 10⁻³), and no evidence for overlap in risk was detected between MDD and seasonality. Common SNPs of large effect most likely do not exist for seasonality in the populations examined. As expected, there were overlapping genetic risk factors for bipolar disorder (but not MDD) with seasonality. Unexpectedly, the risk for schizophrenia and seasonality had the largest overlap, an unprecedented finding that requires replication in other populations and has potential clinical implications considering overlapping cognitive deficits in seasonal affective disorders and schizophrenia.