Seasonality of presentation and birth in catatonia

BACKGROUND

Catatonia is a neuropsychiatric syndrome associated with both psychiatric disorders and medical conditions. Understanding of the pathophysiology of catatonia remains limited, and the role of the environment is unclear. Although seasonal variations have been shown for many of the disorders underlying catatonia, the seasonality of this syndrome has not yet been adequately explored.

METHODS

Clinical records were screened to identify a cohort of patients suffering from catatonia and a control group of psychiatric inpatients, from 2007 to 2016 in South London. In a cohort study, the seasonality of presentation was explored fitting regression models with harmonic terms, while the effect of season of birth on subsequent development of catatonia was analyzed using regression models for count data. In a case-control study, the association between month of birth and catatonia was studied fitting logistic regression models.

RESULTS

In total, 955 patients suffering from catatonia and 23,409 controls were included. The number of catatonic episodes increased during winter, with a peak in February. Similarly, an increasing number of cases was observed during summer, with a second peak in August. However, no evidence for an association between month of birth and catatonia was found.

CONCLUSIONS

The presentation of catatonia showed seasonal variation in accordance with patterns described for many of the disorders underlying catatonia, such as mood disorders and infections. We found no evidence for an association between season of birth and risk of developing catatonia. This may imply that recent triggers may underpin catatonia, rather than distal events.

Systematic review and meta-analysis: Season of birth and schizophrenia risk

OBJECTIVE

Winter birth has been hypothesized to be associated with increased schizophrenia risk for nearly a century. Major hypotheses regarding the potential etiological risk factors for schizophrenia such as vitamin D deficiency and virus exposure in utero are predicated based on the observation that risk of schizophrenia is higher in children born in winter months.

METHODS

We conducted a systematic review and meta-analysis to examine the association between season and month of birth and risk of schizophrenia. We further investigated this relationship stratified by hemisphere.

RESULTS

Forty-three studies spanning 30 countries and territories and 440,039 individuals with schizophrenia were included in this meta-analysis. Winter births were associated with a small but statistically significant increased risk of schizophrenia (OR 1.05, 95 % CI 1.03-1.07, p < 0.0001) and summer births were associated with a small but statistically significant decreased risk of schizophrenia (OR 0.96, 95 % CI 0.94-0.98, p = 0.0001). Stratified subgroup analysis demonstrated no significant difference between hemispheres in the risk of schizophrenia for either winter or summer births.

CONCLUSIONS

Analysis using birth month data demonstrated a clear seasonal trend towards increased risk of schizophrenia being associated with winter birth months and decreased risk of schizophrenia in summer-to-fall months in the Northern but not Southern Hemisphere. These data suggest a small-but-substantial increased risk of schizophrenia in winter birth month. Further research needs to examine potential etiologic causes for this association.

Effect of birth season on allergic rhinitis and cedar pollinosis considering allergen and vitamin D exposure: The Japan Environment and Children's study (JECS)

BACKGROUND

The relationship between the season of birth, allergen sensitization, and allergic rhinitis have been inconsistent, and there are no studies that simultaneously consider vitamin D and allergen exposure. This study aimed to determine the associations between the season of birth, house dust mite (HDM) and Japanese cedar pollen (JCP) sensitization, and allergic rhinitis and pollinosis, while taking vitamin D levels and allergen exposure into account.

METHODS

This study included 4323 participants in the Sub-Cohort Study of the Japan Environment and Children's Study. A logistic regression model was used to analyze the association between the season of birth and sensitization to JCP or HDM (judged by specific immunoglobulin E) at age 2 and allergic rhinitis or pollinosis at age 3, adjusted for HDM or JCP exposure and vitamin D levels with potential confounders.

RESULTS

Participants born in spring or summer were more likely to have pollinosis than were those born in winter (adjusted odds ratio [aOR]: 2.08, 95% confidence interval [CI]: 1.13-3.82 for spring; aOR: 1.89, 95% CI: 1.03-3.47 for summer). Participants born in summer were more likely to have HDM sensitization than were those born in winter (Der p 1, aOR: 1.53, 95% CI: 1.10-2.15; Der f 1, aOR: 1.44, 95% CI: 1.03-2.01). Exposure to JCP and HDM were associated with pollinosis and HDM sensitization, respectively.

CONCLUSIONS

Spring and summer births were associated with the development of pollinosis, and summer birth was associated with HDM sensitization, even when vitamin D and allergen exposure were considered. Further studies on mechanisms other than vitamin D and allergen exposure are required.

Does birth season correlate with childhood stunting? An input for astrological nutrition

INTRODUCTION

Chronic malnutrition is highly prevalent in Sub-Saharan Africa and a severe public health problem in Ethiopia.At country level in the past three decades,the prevalence of stunting is above 40%.Different researchs and intervention were implemented in the past;but the progresss is non-remarkable.Despite; the effect of birth season on childhood chronic malnutrition was not studied yet in Ethiopia.

METHODS

This research was extracted from the 2016 demographic health survey of Ethiopia. The data was collected based on national and international scientific protocols. A total of 645 enumeration areas were selected for the national survey.The surevey uses two stage stratified sampling technique to gather data from the sampling unit. After excluding non eligible children a total of 8855 participants were included for final analysis.Height and weight were measured based on the standards nutritional assessment procedure.SPSS version 20 was used to analyze the data.Descriptive statistics were used to present the data. Binary and multivariable logistic regression models were regressed to identify the potential predictors.A p-value of less than 0.05 with 95% CI were used to declare an association.

RESULT

The prevalence of stunting in Ethiopia was 38.7% (95% CI: 36.8, 40.6). Season of birth had a significant association with stunting. The odds of being stunted among children born in the spring season were decreased by 16% as compared to children born in the winter season.

CONCLUSION

Children born in the spring season were less likely to be stunted (the so called October effect). The clear scientific relation between the season of birth and child anthropometric indicator is not well understood. Nutritional interventions and policies are better to consider the birth season of the child.

Gender differences in the association between environment and psychosis

Various environmental exposures have been associated with psychosis spectrum disorder. However, the role of gender in this association has received little attention. Therefore, we conducted a systematic review to evaluate gender-related differences and identified 47 research articles investigating the associations of psychosis with childhood adversity, substance use, urbanicity, migration, season of birth, and obstetric complication in the PubMed database. The findings suggest that childhood abuse may be more strongly associated with a risk to develop psychosis and an earlier age at onset of illness in women than in men. Furthermore, childhood adversity has been associated with the severity of different symptom dimensions in men and women. Growing up in an urban environment and immigration are more strongly associated with psychosis risk in men than in women. Despite a higher prevalence of substance abuse comorbidity in men diagnosed with psychotic disorders, it appears that the association between substance use and psychosis risk may be stronger in women. These findings should be evaluated with caution considering several methodological limitations, limited number of studies, and lack of consistency across results. Overall, although further investigation is needed, our review shows that gender-related differences in the associations of environmental exposures with psychosis expression may exist.

Dataset on negative symptoms factors in patients with schizophrenia

Schizophrenia is a severe mental disorder characterized by positive and negative symptoms. The negative symptoms are highly relevant to the disease course and outcome. Because negative symptoms show considerable heterogeneity, there is substantial interest in elucidating the negative symptom domains that are characteristic of patient subgroups. It has been proposed that patients with schizophrenia should be classified into deficit and non-deficit groups based on the severity of their negative symptoms. Another method suggested the assessment of the factor structure of negative symptoms to understand its mechanisms. Factor analysis of the different negative symptom rating scales reveals two distinct negative symptom subdomains: diminished expression (DE) and avolition/apathy (AA). These characteristics suggest different pathophysiological mechanisms for the development of AA and DE. We present a large dataset of negative symptom factors calculated for 3006 patients with schizophrenia in the Russian population. Sex, age, age at disease onset and data of birth, including season of birth (SOB), family history of schizophrenia are presented. Negative symptoms were assessed with the Positive and Negative Syndromes Scale (PANSS). We calculated negative symptoms factors as suggested by Liemburg et al. (2013). The data will be useful in assessing the impact of such factors as sex, season of birth (SOB) and family history on the scores of negative symptoms subdomains; such data can help us to better understand the heterogeneity of the negative symptoms of schizophrenia.

The effect of season of birth on brain epigenome-wide DNA methylation of older adults

Perinatal light exposure predisposes towards health and behaviour in adulthood. Season of birth is associated with psychiatric, allergic, cardiovascular and metabolic problems. It has been proposed that early-life environmental light disrupts the development of biological rhythms which, in turn, influence later-life health. However, the mechanisms linking perinatal seasonal light to later-life biological rhythm and health in humans are unknown. In this study, we investigated the association between season of birth and epigenome-wide DNA methylation of two postmortem human brain regions (16 hypothalamus, 14 temporal cortex). We did not find statistically significant differences at the whole epigenome level, either because we lacked statistical power or that no association exists. However, when we examined 24 CpG sites that had the highest significance or differential methylation, we identified regions which may be associated with circadian rhythm entrainment, cholinergic neurotransmission and neural development. Amongst methylation of the core clock genes, we identified that hypothalamus Neuronal PAS Domain Protein 2 (NPAS2) gene has hypermethylated regions in long photoperiod-born individuals. In addition, we found nominal associations between season of birth and genes linked to chronotype and narcolepsy. Season of birth-related brain DNA methylation profile was different than a previously reported blood methylation profile, suggesting a tissue-specific mechanism of perinatal light programming. Overall, we are the first to analyse the relationship between season of birth and human brain DNA methylation. Further studies with larger sample sizes are required to confirm an imprinting effect of perinatal light on the circadian clock.

Impact of Season of Birth on Psychiatric Disorder Susceptibility and Drug Abuse Incidence in a Population from the Köppen Tropical Savanna Region of Brazil

BACKGROUND

Despite much evidence that season of birth (SOB) my influence the vulnerability to psychiatric disorders, divergence has been reported, in particular between populations born in the northern and southern hemispheres. We analyzed the potential modified risk by SOB to psychiatric disorder or drug addiction comorbidity in a population born in the Triângulo Mineiro region, a southern hemisphere Köppen tropical savanna region in Brazil.

METHOD

We accessed the records of 98,457 of patients and healthy controls of the National Datacenter of Medical Promptuary to evaluate the influence of SOB as a modifying factor on the occurrence of mental disorders and drug abuse conditions among individuals born from the year 2000 to 2016.

RESULTS

The data revealed significant modification of the relative incidence of major depressive disorder (MDD) (F11, 72 = 2.898; p = 0.003; eta-squared, ES = 0.313; ⍺ = 0.97), anxiety-related disorder (ARD) (F11, 81 =2.389; p = 0.013; ES = 0.241; ⍺ = 0.932), and schizophrenia (SZ) (F11, 83 = 2.764; p = 0.005; ES = 0.303; α = 0.963), while there was no increase in the number of healthy controls born in any month of the year (F11, 71 = 1.469; p = 0.163). Post hoc analyses indicated a significant higher vulnerability to MDD or ARD if the patient was born in August, or October to December, respectively. A relative increase in the incidence of SZ was also observed in patients born from August to October, compared to patients born from November to January.

CONCLUSIONS

SOB may influence the risk for psychiatric disorders in the TMR population. Regional particularities associated with the climatic regime may account for the apparent divergence between studies.

Season of birth is associated with increased risk of atopic dermatitis in Japanese infants: a retrospective cohort study

Background

Several epidemiological studies have examined the possibility of a relationship between season of birth and atopic dermatitis (AD) and food allergy (FA), yet their results are contradictory. We investigated the association between season of birth and risk of AD and FA in Japanese infants.

Methods

Study subjects were 612 newborn infants born at a single obstetric/pediatric clinic without perinatal diseases. Season of birth was classified as spring (March-May), summer (June-August), autumn (September-November) or winter (December-February). AD was diagnosed according to the United Kingdom Working Party's criteria. FA was defined as present if there was a history of immediate allergic symptoms within 2 h after ingestion of a food. Specific IgE to the corresponding food was also assessed to support the diagnosis. We assessed the association between season of birth and risk of AD and FA using Cox proportional hazard models.

Results

We identified a total of 365 cases of AD occurring during 3659 person-months of follow-up. Compared with summer birth, autumn, winter, and spring birth were significantly positively associated with the risk of AD: adjusted HRs (95% CIs) were 2.67 (1.96-3.63), 1.42 (1.03-1.95), and 1.43 (1.04-1.98), respectively. We identified a total of 23 cases of physician-diagnosed FA occurring during 6815 person-months of follow-up.

Conclusions

Being born in the summer is associated with a lower risk of AD compared to other seasons of birth. The low incidence of FA in our cohort group made it difficult to establish a valid association between FA and season of birth as the statistical power was low.

Interactions between season of birth, chronological age and genetic polymorphisms in determining later-life chronotype

Human chronotype, the temporal pattern of daily behaviors, is influenced by postnatal seasonal programming and ageing. The aim of this study was to investigate genetic variants that are associated with season of birth programming and longitudinal chronotype change. Longitudinal sleep timing and genotype data from 1449 participants were collected for up to 27 years. Gene-environment interaction analysis was performed for 445 candidate single nucleotide polymorphisms that have previously been associated with chronotype. Associations were tested using linear mixed model. We identified 67 suggestively significant genomic loci that have genotype-ageing interaction and 25 genomic loci that may have genotype-season of birth interaction in determining chronotype. We attempted to replicate the results using longitudinal data of the UK Biobank from approximately 30,000 participants. Biological functions of these genes suggest that epigenetic regulation of gene expression and neural development may have roles in these processes. The strongest associated gene for sleep trajectories was ALKBH5, which has functions of DNA repair and epigenetic regulation. A potential candidate gene for postnatal seasonal programming was SIRT1, which has previously been implicated in postnatal programming, ageing and longevity. Genetic diversity may explain the heterogeneity in ageing-related change of sleep timing and postnatal environmental programming of later-life chronotype.

Season of birth, health and aging

We investigate how the season of birth is related to human health and aging. For this purpose, we use five waves of the Survey of Health, Aging, and Retirement in Europe (SHARE) dataset and construct a health deficit index for 21 European countries. Results from log-linear regressions suggest that, on average, elderly European men age faster when they were born in spring and summer (compared to autumn). At any given age, they have developed about 3.5 percent more health deficits. These differences due to seasons of birth are not mediated by body height and education. In a subsample of Southern European countries, where the seasonal variation of sunlight is smaller, the birth season plays an insignificant role for health in old age. In a subsample of Northern countries, in contrast, the season of birth coefficients increase. At any given age, elderly Northern European men born in spring have developed, on average, 8.7 percent more health deficits than those born in autumn. In non-linear regressions we find that the speed of aging is also associated with the birth season.

Season of birth and multiple sclerosis: a systematic review and multivariate meta-analysis

Season of birth is considered to be associated with multiple sclerosis (MS) although some findings opposing to this assumption raise doubts about the seasonality pattern in MS births. The present work synthesizes the evidence of previous published studies aiming at examining whether the month of birth is associated with a higher number of MS births. Pubmed and Scopus were systematically searched and a multivariate meta-analysis of case-control studies was conducted. Data of healthy controls births were retrieved from census reports when not included in the studies. For comparisons, October was set as a reference month and autumn (September-October-November) as a reference season. The meta-analysis included studies that provided the number of MS births for each month or season. Twenty-two eligible studies were included in the meta-analysis involving twenty-four different populations and overall 145,672 MS patients and 75,169,550 healthy controls. The multivariate analysis supports that MS births in spring are higher compared to autumn [odds ratio (OR) 1.14, 95% confidence interval (CI) 1.04, 1.24]. Univariate analyses confirm the same for April (OR 1.12, 95% CI 1.05, 1.21), March (OR 1.05, 95% CI 1.00, 1.11) and May (OR 1.07, 95% CI 1.00, 1.14). A reduction of MS births was found in November (OR 0.96, 95% CI 0.93, 0.99). The month and the season of birth are significantly associated with MS births.

Birth in winter can reduce the risk of lung cancer: A retrospective study of the birth season of patients with lung cancer in Beijing area, China

The season of birth is an important risk factor for several diseases. We explored the relationship between birth season and lung cancer. In this population-based retrospective study, we focused on patients with lung cancer who had registered at the Beijing Institute for Cancer Research from 2003 to 2012. In total, 33,025 patients were divided into five subgroups based on their histologic classification, and these five subgroups were compared with the general population (i.e., the permanent resident population of Beijing in 2013). A binary logistic regression method with sex and age as control factors was used to evaluate the relationship between birth season and lung cancer; P < 0.01 was statistically significant. Taking winter as a reference in our analysis of the relationship between season of birth and lung cancer, we found that people who were born in other seasons had a higher probability of developing lung cancer (spring: odds ratio [OR] = 1.06, 95% confidence interval [CI] = 1.03-1.09; summer: OR = 1.07, 95% CI = 1.04-1.10; autumn: OR = 1.06, 95% CI = 1.03-1.09) (P < 0.01). Among the five subgroups, persons with squamous cell carcinoma who were born in summer were more likely to develop lung cancer than those who were born in winter (OR = 1.09, 95% CI = 1.02-1.15, P = 0.006). The other subgroups showed no correlation with season of birth (P > 0.01). This study demonstrates that for people born in winter, the risks of developing lung cancer and squamous cell carcinoma are comparatively lower than those for people born in other seasons. Differences in immune function and the maternal nutrition status during pregnancy of people born in different seasons may explain this finding.

Effect of season of birth on cord blood IgE and IgE at birth: A systematic review and meta-analysis

BACKGROUND

Elevated cord blood IgE is important on the pathway to allergic disease. The association between season of birth and infant cord blood IgE is not well-established. Study findings differ on which birth season is associated with higher cord blood IgE risk and its magnitude. We conducted a systematic review and meta-analysis of studies on season of birth and cord blood IgE.

METHODS

We searched Medline, Web of Science, Scopus and ProQuest Health databases, and reviewed reference lists of articles that met the inclusion criteria. All included studies measured IgE as a binary variable using various cut-off values. We performed multivariate-random-effects meta-analysis to handle an exposure with multiple categories of Season of Birth.

RESULTS

Our search identified 275 records and 10 had sufficient data to be included in a meta-analysis. Relative to summer, winter birth had the greatest odds of high IgE (≥ 0.1IU/ml), meta-analysis OR = 1.24 (95%CI: 1.01-1.52). A similar OR, was found for IgE ≥ 0.5 IU/ml, OR = 1.30 (95%CI: 0.99-1.71).

CONCLUSIONS

A winter season of birth was associated with statistically significant higher odds of elevated cord blood IgE at cut-off ≥ 0.1IU/ml but borderline at cut-off ≥ 0.5IU/ml. This winter effect is likely to be a marker for a range of other environmental exposures during specific stages of pregnancy, such as aeroallergen exposures, maternal infections and vitamin D levels. Further research is required to support our finding and to identify the exact mechanisms that lead to the winter season of birth effect on circulating IgE levels, as this may have implications for allergic disease prevention.

Comparing effects: a reanalysis of two studies on season of birth bias in anorexia nervosa

BACKGROUND

Outcomes from studies on season of birth bias in eating disorders have been inconsistent. This inconsistency has been explained by differences in methodologies resulting in different types of effect sizes. The aim of the current study was to facilitate comparison by using the same methodology on samples from two studies with differing conclusions.

METHODS

The statistical analyses used in each study were applied to the samples from the other study and the resulting effect sizes, Cramêr's V and odds ratio (OR), were compared and discussed.

RESULTS

For both studies, the Cramêr's Vs ranged between 0.03 and 0.08 and the OR ranged between 0.85 and 1.31. According to common conventions, Cramêr's Vs below 0.10 and ORs below 1.44 are considered small.

CONCLUSION

As a marker of one or more potential risk factors, the observed effects are considered to be small. When reanalysed allowing for direct comparisons, studies with contrasting conclusions converge towards an absence of support for a season of birth bias for patients with AN.

No seasonality of birth in BMI at 7years of age

Seasonal variation in birth weight was found in a previous Danish study. In the present study we investigated if the seasonality in birth weight tracked into BMI at 7years of age, but found no seasonality of birth in either BMI, overweight, or obesity.

Clinical Correlates of Co-occurring Psychiatric and Autism Spectrum Disorder (ASD) Symptom-Induced Impairment in Children with ASD

Although psychiatric symptom severity and impairment are overlapping but nevertheless distinct illness parameters, little research has examined whether variables found to be associated with the severity are also correlated with symptom-induced impairment. Parents and teachers completed ratings of symptom-induced impairment for DSM-IV-referenced syndromes, and parents completed a background questionnaire for a consecutively referred sample of primarily male (81%) 6-to-12 year olds with autism spectrum disorder (ASD) (N = 221). Some clinical correlates (e.g., IQ < 70, maternal level of education, pregnancy complications, current use of psychotropic medication, season of birth) were associated with impairment for several disorders, whereas others were correlated with only a few syndromes (e.g., gender, co-morbid medical conditions) or were not related to impairment in any disorder (e.g., family psychopathology). There was little convergence in findings for parents' versus teachers' ratings. Some clinical correlates (e.g., season of birth, current psychotropic medication, maternal education) were unique predictors of three or more disorders. Pregnancy complications were uniquely associated with social anxiety and schizoid personality symptom-induced impairment. IQ was a unique predictor of schizophrenia, ASD, oppositional defiant disorder symptom-induced impairment. Children whose mothers had relatively fewer years of education had greater odds for symptom-induced impairment in social anxiety, depression, aggression, and mania and greater number of impairing conditions. Season of birth was the most robust correlate of symptom-induced impairment as rated by teachers but not by parents. Children born in fall evidenced higher rates of co-occurring psychiatric and ASD symptom-induced impairment and total number of impairing conditions. Many variables previously linked with symptom severity are also correlated with impairment.

Season of birth and population schizotypy: Results from a large sample of the adult general population

Although the last years have seen an increasing interest in schizotypy and its pathogenesis, there exist only a handful of studies examining the possible interaction between season of birth (SOB) and schizotypic personality structure. Available research used differing screening instruments, rendering comparisons between studies difficult, and sample sizes in adult populations may have been too small to detect a mild effect. The current study examined the association between SOB and psychometric schizotypy in the so far single-largest sample from the adult general population (N=8114), balanced for men and women, and utilizing a valid and reliable instrument for the assessment of schizotypy. Using the 12 most informative items of the Schizotypal Personality Questionnaire Brief, we obtained evidence of a small, but significant, effect of late winter and early spring births (February/March) on psychometric schizotypy. The effect was not constrained to women, but affected men and women alike. The observed association between SOB and schizotypy appears compatible with seasonal variations of temperature and influenza prevalence, and with recent evidence on seasonal variability in the activity of the human immune system. Our findings lend support to the continuum hypothesis of schizotypy and schizophrenia, for which SOB effects have been previously established.

Impact of the birth's season on the development of celiac disease in Italy

Celiac disease (CD) is an immune-mediated systemic disorder induced by a trigger factor in genetically susceptible individuals. There is emerging evidence about the impact of the month of birth on the development of several autoimmune diseases. Our aim was to investigate whether, in Italian CD children, the season of birth is associated with development of CD later in life. We report a survey conducted at two Italian referral centers for CD in Rome and Bari. The CD database was created to enable retrospective examination of the data of all the consecutive patients, born between 2003 and 2010, who had received a diagnosis of CD. This CD patient group comprising 596 children was compared with a reference group that included all subjects born in the same period and in the same cities (439,990 controls). Overall, there was a summer birth preponderance in CD patients compared to controls (28.2 % of CD patients vs 23.0 % of the control population; OR 1.315; 95 % CI 1.100 to 1.572). Stratifying the caseload by gender and age, the summer birth preponderance was maintained for females (28.6 % CD females vs 22.6 % control females; OR 1.368; 95 % CI 1.069 to 1.750).

CONCLUSIONS

our survey confirms that in Italy, children born in summer are at higher risk to develop CD than subjects born in other seasons. The identification of a responsible seasonal factor or factors, such as timing of the first introduction of gluten and/or acute viral gastrointestinal infections, would be very important for disease prevention strategies.

WHAT IS KNOWN

• Environmental factors could be involved in the pathogenesis of CD. • Data about the impact of season of birth on CD development is so far derived from North American, Northern European and Israeli surveys.

WHAT IS NEW

• This is the first study in Southern Europe to find a relationship between season of birth (summer) and development of CD. • Summer-born infants are introduced to complementary feeding (gluten) in winter, when the rotavirus infection is at its highest peak; this may be the link between season of birth and development of CD.

Season of birth and subclinical psychosis: systematic review and meta-analysis of new and existing data

Season of birth (SOB) has been shown to modify the risk of several health outcomes, including a number of neuropsychiatric disorders. Empirical evidence indicates that subclinical forms of psychosis in the general population share some risk factors with categorical diagnoses of psychosis. Hence, by systematically reviewing and meta-analyzing new and existing data, the current work aimed to determine whether there is evidence of an association between winter SOB and subclinical psychosis in the general population. Our meta-analytic results do not indicate an association between winter SOB and schizotypy in adult populations, although they indicate winter SOB may be a risk factor for psychotic experiences or symptoms in children around 12-15 years (OR=1.12, 95%CI:1.03-1.21). In the whole new dataset for adults (n=481, mean age=22.8 years) no association was detected in either an unadjusted model or adjusting for gender and age. Overall, our results indicate that the association between winter SOB and increased subclinical psychosis may hold in children, but does not in the broad general adult population. Nevertheless, the epidemiological and clinicopathological significance of winter SOB as a risk factor for subclinical psychosis would probably be slight due to the small effect sizes indicated by the reports available to date.

Cortical thickness correlates of psychotic experiences: examining the effect of season of birth using a genetically informative design

Season of birth has been shown to influence risk for several neuropsychiatric diseases. Furthermore, it has been suggested that season of birth modifies a number of brain morphological traits. Since cortical thickness alterations have been reported across some levels of the psychosis-spectrum, this study was aimed at i) assessing the scarcely explored relationship between cortical thickness and severity of subclinical psychotic experiences (PEs) in healthy subjects, and ii) evaluating the potential impact of season of birth in the preceding thickness-PEs relationship. As both PEs and brain cortical features are heritable, the current work used monozygotic twins to separately evaluate familial and unique environmental factors. High-resolution structural MRI scans of 48 twins (24 monozygotic pairs) were analyzed to estimate cortical thickness using FreeSurfer. They were then examined in relation to PEs, accounting for the effects of birth season; putative differential relationships between PEs and cortical thickness depending on season of birth were also tested. Current results support previous findings indicative of cortical thickening in healthy individuals with high psychometrically assessed psychosis scores, probably in line with theories of compensatory aspects of brain features in non-clinical populations. Additionally, they suggest distinct patterns of cortical thickness-PEs relationships depending on birth seasonality. Familial factors underlying the presence of PEs may drive these effects.

Season of birth, mixed-handedness, and psychometric schizotypy: preliminary results from a prospective study

Season of birth and hand preference were examined in a sample of 42 (7 males, 35 females) individuals who were identified as schizotypic based on their scores on selected scales of the Chapman Psychosis Proneness Scales (CPPS) and a matched comparison sample of 42 individuals with non-deviant CPPS scores. Presence or absence of schizotypy was analyzed using chi square tests of independence with the presence or absence of each risk factor serving as the independent variable. Further analyses incorporated independent means t tests to examine mean scores on the CPPS with the presence or absence of each risk factor again serving as the independent variable. Results supported the hypothesis that winter/early-spring birth would be associated with psychometric schizotypy, although the results for mixed-handedness fell just short of statistical significance. However, mixed hand preference was associated with higher scores on MagId and PerAb scales of the CPPS, but not the RSA scale, which suggests that mixed laterality is associated with the more cognitive-perceptual aspects of schizotypy. Results are discussed in relation to previous literature and their relevance to the prediction of schizophrenia-related psychosis.