Seasonality of birth in patients with mood disorders in Japan

Perinatal photoperiod associations with bipolar disorder and depression: A systematic literature review and cross-sectional analysis of the UK Biobank database

Season-of-birth associations with psychiatric disorders point to environmental (co-)aetiological factors such as natural photoperiod that, if clarified, may allow interventions toward prevention. We systematically reviewed the literature concerning season-of-birth and bipolar disorder and depression and explored associations between the perinatal natural photoperiod and these outcomes in a cross-sectional analysis of the UK Biobank database. We used mean daily photoperiod and relative photoperiod range (relative to the mean) in the 3rd trimester and, separately, in the first 3 months post birth as metrics. From review, increased risk of depression with late spring birth is compatible with increased odds of probable single episode-, probable recurrent-, and diagnosed depression (OR 2.85 95 %CI 1.6-5.08, OR 2.20 95 %CI 1.57-3.1, and OR 1.48 95 %CI 1.11-1.97, respectively) with increasing 3rd trimester relative photoperiod range for participants who experienced relatively non-extreme daily photoperiods. Risk of bipolar disorder with winter-spring birth contrasted with no consistent patterns of perinatal photoperiod metric associations with bipolar disorder in the UK Biobank. As natural photoperiod varies by both time-of-year and latitude, perinatal natural photoperiods (and a hypothesized mechanism of action via the circadian timing system and/or serotonergic circuitry associated with the dorsal raphe nucleus) may reconcile inconsistencies in season-of-birth associations. Further studies are warranted.

Early life climate and adulthood mental health: how birth seasonality influences depressive symptoms in adults

BACKGROUND

Early life in-utero can have long-term influence on the mental health status of individuals in adulthood, such as depression. Age, gender, socio-economic status, education, and geography are demographic factors shown to be particularly vulnerable towards the development of depressive symptoms. In addition, climate risks on depression include sunlight, rain, and temperature. However, whether climate factors in early life have a long-term influence on depression related to demographic vulnerability remains unknown. Here, the present study explored the association between birth seasonality and adulthood depressive symptoms.

METHODS

We employed data from the project of Chinese Labour-forces Dynamic Survey (CLDS) 2016, containing the epidemiological data of depressive symptoms with a probability proportional to size cluster and random cluster sampling method in 29 provinces of China. A final sample size of 16,185 participants was included. Birth seasonality included spring (March, April, and May), summer (June, July, and August), autumn (September, October, and November), and winter (December, January, and February).

RESULTS

We found that born in Autumn peaked lowest rate of having depressive symptoms (16.8%) and born in Summer (vs. Autumn) had a significant higher ratio (OR = 1.14, 95%CI = 1.02, 1.29) when controlling for demographic variables. In addition, demographic odds ratio of having depressive symptoms differed between people born in different seasons, particular for age and geography.

CONCLUSION

Our findings suggest that birth seasonality influences the sensitive link of depressive symptoms with age and geography. It implicates early life climate environment may play a role in the development of adulthood depressive symptoms.

Month of birth and mental disorders: A population-based study and validation using global meta-analysis

OBJECTIVE

Month of birth (MOB) is associated with specified mental disorders (MDs). However, whether these relationships extend to all MDs remains unclear. We investigate the association using a population-based cohort study and a meta-analysis.

METHODS

First, we examined patients with 34 DSM-5-classified MDs in the Taiwan national database. We estimated the relative risk ratios (RR) of each illness in each MOB relative to that in the general population and assessed the periodicity, with six further sensitivity analyses. Second, we searched PubMed, Embase, and Cochrane for related articles through 31 December 2020. We used a random-effects model, pooled RRs with 95% confidence intervals of each MOB from the identified studies, and transformed them from MOB to relative age in a year or season.

RESULTS

The cohort included 1,951,777 patients. Except for posttraumatic stress disorder, dissociative disorders, feeding/eating disorders, gender dysphoria, and paraphilic disorders, the other MDs had significant MOB periodicity. The meta-analysis included 51 studies investigating 10 MDs. The youngest age at the start of school owing to MOB was associated with the highest RRs of intellectual disability (1.13), autism (1.05), attention-deficit/hyperactivity disorder (1.13). Winter births had significant risks of schizophrenia (1.04), bipolar I disorder (1.02), and major depressive disorder (1.01), and autumn births had a significant risk of alcohol use disorder (1.02). No significant associations between season of birth and Alzheimer's disease, or eating disorders were found.

CONCLUSIONS

MOB is related to the risks of certain MDs. This finding provides a reference for future research on the etiology of MDs.

Short-active photoperiod gestation induces psychiatry-relevant behavior in healthy mice but a resiliency to such effects are seen in mice with reduced dopamine transporter expression

A higher incidence of multiple psychiatric disorders occurs in people born in late winter/early spring. Reduced light exposure/activity level impacts adult rodent behavior and neural mechanisms, yet few studies have investigated such light exposure on gestating fetuses. A dysfunctional dopamine system is implicated in most psychiatric disorders, and genetic polymorphisms reducing expression of the dopamine transporter (DAT) are associated with some conditions. Furthermore, adult mice with reduced DAT expression (DAT-HT) were hypersensitive to short active (SA; 19:5 L:D) photoperiod exposure versus their wildtype (WT) littermates. Effects of SA photoperiod exposure during gestation in these mice have not been examined. We confirmed adult females exhibit a heightened corticosterone response when in SA photoperiod. We then tested DAT-HT mice and WT littermates in psychiatry-relevant behavioral tests after SA or normal active (NA; 12:12 L:D) photoperiod exposure during gestation and early life. SA-born WT mice exhibited sensorimotor gating deficits (males), increased reward preference, less immobility, open arm avoidance (females), less motivation to obtain a reward, and reversal learning deficits, vs. NA-born WT mice. DAT-HT mice were largely resilient to these effects, however. Future studies will determine the mechanism(s) by which SA photoperiod exposure influences brain development to predispose toward emergence of psychiatry-relevant behaviors.

Maternal inflammation during pregnancy and offspring psychiatric symptoms in childhood: Timing and sex matter

OBJECTIVE

Maternal infection during pregnancy has been associated with increased risk of offspring psychopathology, including depression. As most infections do not cross the placenta, maternal immune responses to infection have been considered as potentially contributing to this relationship. This study examined whether gestational timing of maternal inflammation during pregnancy is associated with offspring internalizing and/or externalizing symptoms during childhood and, further, whether fetal sex moderated this relationship.

METHOD

Participants were 737 pregnant women and their offspring who were continuously followed through late childhood. Archived first and second trimester sera were analyzed for markers of inflammation [interleukin 8 (IL-8), IL-6, IL-1 receptor antagonist (IL-1ra), and soluble tumor necrosis factor receptor-II (sTNF-RII)]. When offspring were aged 9-11, mothers completed a questionnaire assessing psychological symptoms.

RESULTS

Multivariate regression analyses indicated that elevated IL-8 in the first trimester was associated with significantly higher levels of externalizing symptoms in offspring. Higher IL-1ra in the second trimester was associated with higher offspring internalizing symptoms. Further, second trimester IL-1ra was associated with increased internalizing symptoms in females only.

CONCLUSION

These findings demonstrate that elevated maternal inflammation during pregnancy is associated with the emergence of separate psychological phenotypes and that timing of exposure and fetal sex matter for offspring outcomes. Given that internalizing and externalizing symptoms in childhood increase risk for a variety of mental disorders later in development, these findings potentially have major implications for early intervention and prevention work.

Birth Month and Course of Recurrent Depressive Disorders in a Polish Population

BACKGROUND The aim of this study was to determine whether the specific season of the year during which the first trimester of pregnancy takes place is significantly associated with the course (intensification and frequency of occurrence) of an episode of recurrent depressive disorder in adult life. MATERIAL AND METHODS We enrolled 184 patients treated for recurrent depressive disorders. RESULTS An analysis of the results obtained indicates that the greatest number of people suffering from a major depressive episode were born in the spring and summer (from April to September), meaning that the first trimester of pregnancy occurred between October and March. However, our results were not statistically significant, perhaps due to the small size of the examined group. CONCLUSIONS The results obtained indicate that birth month may be significantly associated with the course of recurrent depressive disorders. In patients from Central Europe, the first trimester of pregnancy falling in autumn and winter seems to be significant. These results need to be interpreted with caution due to the small size of the examined group.

Season of birth in suicides: excess of births during the summer among schizophrenic suicide victims

BACKGROUND

Season of birth is associated with several psychiatric disorders and suicidal behavior. We explored the association between the season of birth and suicide among schizophrenic and psychotic suicide victims.

METHODS

The study sample consisted of all suicides in the province of Oulu in Northern Finland from 1989 to 2010. Causes of death were extracted from death certificates, and psychiatric diagnoses associated with the hospital treatments were obtained from the Finnish Hospital Discharge Register. The seasons were defined as follows: winter (from November to January), spring (from February to April), summer (from May to July), and autumn (from August to October). Suicide victims (n = 1,902) were categorized as having either schizophrenia (n = 228) or psychosis other than schizophrenia (n = 240). Suicide victims without any hospital-treated mental disorder (n = 1,434) were used as a comparison group.

RESULTS

The distribution of births among suicide victims with schizophrenia differed statistically significantly from that observed in the general population, with a peak in summer (OR 1.2, 95% CI 1.0-1.5).

CONCLUSIONS

Birth during summer may predispose schizophrenic persons to suicide. The putative roles of serotonin, dopamine, and vitamin D status in the season of birth of psychotic suicide victims are discussed.

Star-crossed? The association of the 5-HTTLPR s allele with season of birth in a healthy female population, and possible consequences for temperament, depression and suicide

BACKGROUND

Birth season has well-known effects on neuropsychiatric disorders, and may also influence genotype distribution by possibly influencing chance of conception via parental idiosyncratic conception patterns or survival of foetuses or infants. The 5-HTTLPR is associated with phenomena including affective temperaments or suicide which are also associated with birth season. Our aim was to investigate the association of 5-HTTLPR genotype and birth season in a healthy female population.

METHODS

Birth date and 5-HTTLPR genotype was determined for 327 psychiatrically healthy women. The association between presence of s allele and time of birth was analysed using generalized linear models.

RESULTS

A significant association between s allele frequency and time of birth was detected. S allele carrier frequency was marginally significantly higher in July borns and significantly lower in autumn borns.

LIMITATIONS

We investigated an adult sample so genotype frequency data do not reflect birth frequencies. Our sample consisted exclusively of females.

CONCLUSIONS

There is no clear explanation for the observed association, although idiosyncratic parental conception patterns, the association of 5-HTTLPR with sudden infant/intrauterine death, or other s allele-mediated behaviours may play a role. Our results are strikingly parallel with earlier data reporting a higher risk of completed suicide in July borns, and higher scores of July borns and lower scores of autumn borns on certain affective temperament scales, both of which are also associated with the s allele of 5-HTTLPR. Thus our results may add to the growing body of evidence regarding the etiological background of affective disorders.

Interactions of the serotonin and circadian systems: nature and nurture in rhythms and blues

The serotonin and circadian systems are principal regulatory networks of the brain. Each consists of a unique set of neurons that make widespread neural connections and a defined gene network of transcriptional regulators and signaling genes that subserve serotonergic and circadian function at the genetic level. These master regulatory networks of the brain are extensively intertwined, with reciprocal circuit connections, expression of key genetic elements for serotonin signaling in clock neurons and expression of key clock genes in serotonergic neurons. The reciprocal connections of the serotonin and circadian systems likely have importance for neurobehavioral disorders, as suggested by their convergent contribution to a similar range of mood disorders including seasonal affective disorder (SAD), bipolar disorder, and major depression, and as suggested by their overlapping relationship with the developmental disorder, autism spectrum disorder. Here we review the neuroanatomical and genetic basis for serotonin-circadian interactions in the brain, their potential relationship with neurobehavioral disorders, and recent work examining the effects on the circadian system of genetic perturbation of the serotonergic system as well as the molecular and behavioral effects of developmental imprinting of the circadian system with perinatal seasonal light cycles.

Association between affective temperaments and season of birth in a general student population

BACKGROUND

Several studies indicate a significant association between birth season and personality and neuropsychiatric disorders. The aim of our present study was to investigate the association between affective temperaments and season of birth in a nonclinical sample.

METHODS

366 university students completed the standardized Hungarian version of the Temperament Evaluation of Memphis, Pisa, Paris and San Diego-Auto-questionnaire (TEMPS-A). Ordinary Least Squares regression was applied to explain the relationship between TEMPS-A subscale and birth season of the respondents.

RESULTS

We found a significant association between temperament scores and birth season in the case of the Hyperthymic, Cyclothymic, Irritable and Depressive temperaments, while no significant results emerged for the Anxious temperament.

LIMITATIONS

The relatively small sample size, especially in the case of seasonal and monthly subsamples limits generalization of our results.

CONCLUSIONS

Our results support the evidence that there is a strong association between season of birth and personality, extending the results to affective temperaments as well. Furthermore, our results are in line with clinical observations concerning the seasonal variation of onset and hospitalization due to affective episodes. This is especially important, since affective temperaments are conceived as the subaffective and subclinical manifestations of major and minor affective disorders indicating a risk for the development of these disorders and also exerting a possible pathoplastic effect, thus our results also have clinical significance.

Season of birth is significantly associated with the risk of completed suicide

BACKGROUND

Previous studies have provided somewhat inconsistent results about the effects of season of birth on the risk of suicidal behavior. Therefore, we decided to investigate this question in a large sample of suicide completers.

METHODS

We determined the season of birth-associated risk of completed suicide between the years 1970 and 2008 among all individuals who were born in the area of today's Hungary between 1930 and 1939, 1941 and 1942, and 1944 and 1969.

RESULTS

The final sample of participants included around six and a half million people. About 80,000 completed suicides occurred among participants during the period investigated (the number of suicide completers in our study greatly exceeds the number of suicide completers in any previous studies). A significantly (p < .05) elevated risk of completed suicide was found among those individuals who were born in the high-risk period (spring and summer). Quantitatively, the biggest increase (7.6% [95% confidence interval: 5.4-9.9]) in suicide risk was detected among those who were born in July compared with the average risk of suicide in the population investigated. The associations between season of birth and the risk of completed suicide were stronger among male subjects than among female subjects and among those who committed suicide using violent methods than among those who chose nonviolent methods.

CONCLUSIONS

Our results from a large sample of suicide completers from Hungary--a country with one of the highest suicide rates in the world over the last century--strongly support the concept that the season of birth is significantly associated with the risk of completed suicide.

Effect of month of birth on personality traits of healthy Japanese

The effect of month of birth on personality traits was investigated in 595 healthy Japanese. Personality traits were evaluated by the Temperament and Character Inventory (TCI). Statistical analyses were conducted in two steps. Firstly, months of the year were divided according to ambient temperature or photoperiod, and TCI scores were compared between month groups by analysis of covariance (ANCOVA) with age as a covariate. Secondly, multiple regression analysis was performed with TCI scores as dependent variables and ambient temperature and photoperiod at birth month and age as independent variables. Both analyses showed that higher ambient temperature at birth month was related to higher scores of self-directedness and persistence in females. Also, higher ambient temperature at birth month was related to lower body mass index (BMI) in females. These results suggest that month of birth affects self-directedness and persistence in healthy Japanese females, and these effects may be mediated by BMI changes associated with ambient temperature at birth month.

Dates of birth and seasonal changes in well-being among 4904 subjects completing the seasonal pattern assessment questionnaire

BACKGROUND

Abnormal distributions of birthdates, suggesting intrauterine aetiological factors, have been found in several psychiatric disorders, including one study of out-patients with Seasonal Affective Disorder (S.A.D.). We investigated birthdate distribution in relation to seasonal changes in well-being among a cohort who had completed the Seasonal Pattern Assessment Questionnaire (SPAQ).

METHOD

A sample of 4904 subjects, aged 16 to 64, completed the SPAQ. 476 were cases of S.A.D. on the SPAQ and 580 were cases of sub-syndromal S.A.D. (S-S.A.D.). 92 were interview confirmed cases of S.A.D. Months and dates of birth were compared between S.A.D. cases and all others, between S.A.D. and S-S.A.D. cases combined and all others, and between interview confirmed cases and all others. Seasonality, as measured through seasonal fluctuations in well-being on the Global Seasonality Scores (GSS) of the SPAQ, was compared for all subjects by month and season of birth.

RESULTS

There was no evidence of an atypical pattern of birthdates for subjects fulfilling criteria for S.A.D., for the combined S.A.D./S-S.A.D. group or for interview confirmed cases. There was also no relationship between seasonality on the GSS and month or season of birth.

LIMITATIONS

Diagnoses of S.A.D. made by SPAQ criteria are likely to be overinclusive.

CONCLUSION

Our findings differ from studies of patients with more severe mood disorders, including psychiatric out-patients with S.A.D. The lack of association between seasonality and birthdates in our study adds credence to the view that the aetiology of S.A.D. relates to separable factors predisposing to affective disorders and to seasonality.

Season of birth, clinical manifestations and Dexamethasone Suppression Test in unipolar major depression

BACKGROUND

Reports in the literature suggest that the season of birth might constitute a risk factor for the development of a major psychiatric disorder, possibly because of the effect environmental factors have during the second trimester of gestation. The aim of the current paper was to study the possible relationship of the season of birth and current clinical symptoms in unipolar major depression.

METHODS

The study sample included 45 DSM-IV major depressive patients and 90 matched controls. The SCAN v. 2.0, Hamilton Depression Rating Scale (HDRS) and Hamilton Anxiety Scale (HAS) were used to assess symptomatology, and the 1 mg Dexamethasone Suppression Test (DST) was used to subcategorize patients.

RESULTS

Depressed patients as a whole did not show differences in birth season from controls. However, those patients born during the spring manifested higher HDRS while those born during the summer manifested the lowest HAS scores. DST non-suppressors were almost exclusively (90%) likely to be born during autumn and winter. No effect from the season of birth was found concerning the current severity of suicidal ideation or attempts.

DISCUSSION

The current study is the first in this area of research using modern and rigid diagnostic methodology and a biological marker (DST) to categorize patients. Its disadvantages are the lack of data concerning DST in controls and a relatively small size of patient sample. The results confirm the effect of seasonality of birth on patients suffering from specific types of depression.

The relation of season of birth to severity of menopausal symptoms

OBJECTIVE

Season of birth influences the rate of several psychiatric disorders. In this study, we investigated whether climacteric symptoms and, in particular, psychological and somatic symptoms of postmenopausal women were influenced by their season of birth.

DESIGN

This retrospective multicenter study was performed on 2,541 women in natural menopause, free of hormone therapy. The score of the Greene Climacteric Scale and of its vasomotor, psychological (anxiety and depression), and somatization subscales were stratified by season of a woman's birth. Data were controlled for possible confounders, such as age, years since menopause, body mass index, education occupation, smoking habits, and season of evaluation.

RESULTS

The Greene Climacteric Scale appeared to be associated with the season of birth, with the lowest scores being observed in women born in autumn and the highest scores in women born in spring (+2.11; 95% CI, 0.67-3.56; P = 0.01), and summer (+2.22; CI, 0.82-3.63; P = 0.01). Lowest scores in autumn and highest scores in spring were also observed for psychological symptoms subscaled as anxiety and depression (+1.43; CI, 0.54-2.32; P = 0.01) and somatic symptoms (+0.59; CI, 0.15-1.04; P = 0.01).

CONCLUSIONS

In this study, we found a relationship between season of birth and some menopause-associated symptoms. Further study is needed to confirm these relationships and examine possible mechanisms.

Seasonality of birth in patients with schizophrenia in Japan

Although most Western studies have found a birth excess during winter or early spring among patients with schizophrenia, this has not been found in Japanese samples. The purpose of the present paper was to investigate this finding using a large Japanese sample. Distributions of monthly birth numbers of patients with schizophrenia were compared to those of the general population. Patients were from the governmental data, numbering 88 788. A significant birth excess during winter to early spring was found in male and female subjects with schizophrenia compared to the general population. There is a significant birth excess during winter to early spring for schizophrenia in Japan. The authors consider that the discrepancy between the current study and the previous Japanese studies was caused by small sample size and selection bias in the previous Japanese studies.

Risk factors in relation to an emergence of bipolar disorder: a systematic review

OBJECTIVE

There is a consensus that genetic factors are important in the causation of bipolar disorder (BPD); however, little is known about other risk factors in the aetiology of BPD. Our aim was to review the literature on such risk factors - risk factors other than family history of affective disorders - as predictors for the initial onset of BPD.

METHODS

We conducted a literature search using the MEDLINE, PsycINFO and EMBASE databases. We selected factors of interest including demographic factors, factors related to birth, personal, social and family backgrounds, and history of medical conditions. The relevant studies were extracted systematically according to a search protocol.

RESULTS

We identified approximately 100 studies that addressed the associations between antecedent environmental factors and a later risk for BPD. Suggestive findings have been provided regarding pregnancy and obstetric complications, winter-spring birth, stressful life events, traumatic brain injuries and multiple sclerosis. However, evidence is still inconclusive. Childbirth is likely to be a risk factor. The inconsistency across studies and methodological issues inherent in the study designs are also discussed.

CONCLUSION

Owing to a paucity of studies and methodological issues, risk factors of BPD other than family history of affective disorders have generally been neither confirmed nor excluded. We call for further research.