Postpartum depressive symptoms and the BDNF Val66Met functional polymorphism: effect of season of delivery

Application of time series analysis in predicting postpartum depression: integrating data from the hospitalization period and early postpartum weeks

PURPOSE

This study aimed to explore the dynamic changes in postpartum depressive symptoms from the hospitalization period to 4-8 weeks postpartum using time series analysis techniques. By integrating depressive scores from the hospital stay and the early postpartum weeks, we sought to develop a predictive model to enhance early identification and intervention strategies for Postpartum Depression (PPD).

METHODS

A longitudinal design was employed, analyzing Edinburgh Postnatal Depression Scale (EPDS) scores from 1,287 postpartum women during hospitalization and at 4, 6, and 8 weeks postpartum. Descriptive statistics summarized demographic characteristics. Time Series Analysis using the Auto-Regressive Integrated Moving Average (ARIMA) model explored temporal trends and seasonal variations in EPDS scores. Correlation analysis examined the relationships between EPDS scores and demographic characteristics. Model validation was conducted using a separate dataset.

RESULTS

EPDS scores significantly increased from the hospitalization period to 4-8 weeks postpartum (p < .001). The ARIMA model revealed seasonal and trend variations, with higher depressive scores in the winter months. The model's fit indices (AIC = 765.47; BIC = 774.58) indicated a good fit. The Moving Average (MA) coefficient was - 0.69 (p < .001), suggesting significant negative impacts from previous periods' errors.

CONCLUSIONS

Monitoring postpartum depressive symptoms dynamically was crucial, particularly during the 4-8 weeks postpartum. The seasonal trend of higher depressive scores in winter underscored the need for tailored interventions. Further research using longitudinal and multi-center designs was warranted to validate and extend these findings. Our predictive model aimed to enhance early identification and intervention strategies, contributing to better maternal and infant health outcomes.

Identification of risk loci for postpartum depression in a genome-wide association study

AIM

Genome-wide association studies (GWAS) of postpartum depression (PPD) based on accumulated cohorts with multiple ethnic backgrounds have failed to identify significantly associated loci. Herein, we conducted a GWAS of Japanese perinatal women along with detailed confounding information to uncover PPD-associated loci.

METHODS

The first and second cohorts (n = 9260 and n = 8582 perinatal women enrolled in the Tohoku Medical Megabank Project) and the third cohort (n = 997), recruited at Nagoya University, underwent genotyping. Of them, 1421, 1264, and 225 were classified as PPD based on the Edinburgh Postnatal Depression Scale 1 month after delivery. The most influential confounding factors of genetic liability to PPD were selected, and logistic regression analyses were performed to evaluate genetic associations with PPD after adjusting for confounders.

RESULTS

A meta-analysis of GWAS results from the three cohorts identified significant associations between PPD and the following loci (P < 5 × 10-8) by integrating the number of deliveries and the number of family members living together as the most influential confounders: rs377546683 at DAB1, rs11940752 near UGT8, rs141172317, rs117928019, rs76631412, rs118131805 at DOCK2, rs188907279 near ZNF572, rs504378, rs690150, rs491868, rs689917, rs474978, rs690118, rs690253 near DIRAS2, rs1435984417 at ZNF618, rs57705782 near PTPRM, and rs185293917 near PDGFB. Pathway analyses indicated that SNPs suggestively associated with PPD were mostly over-represented in categories including long-term depression, GnRH signaling, glutamatergic synapse, oxytocin signaling, and Rap1 signaling.

CONCLUSION

The current GWAS study identified eight loci significantly associated with PPD, which may clarify the genetic structure underlying its pathogenesis.

Bridging Neurobiological Insights and Clinical Biomarkers in Postpartum Depression: A Narrative Review

Postpartum depression (PPD) affects 174 million women worldwide and is characterized by profound sadness, anxiety, irritability, and debilitating fatigue, which disrupt maternal caregiving and the mother-infant relationship. Limited pharmacological interventions are currently available. Our understanding of the neurobiological pathophysiology of PPD remains incomplete, potentially hindering the development of novel treatment strategies. Recent hypotheses suggest that PPD is driven by a complex interplay of hormonal changes, neurotransmitter imbalances, inflammation, genetic factors, psychosocial stressors, and hypothalamic-pituitary-adrenal (HPA) axis dysregulation. This narrative review examines recent clinical studies on PPD within the past 15 years, emphasizing advancements in neuroimaging findings and blood biomarker detection. Additionally, we summarize recent laboratory work using animal models to mimic PPD, focusing on hormone withdrawal, HPA axis dysfunction, and perinatal stress theories. We also revisit neurobiological results from several brain regions associated with negative emotions, such as the amygdala, prefrontal cortex, hippocampus, and striatum. These insights aim to improve our understanding of PPD's neurobiological mechanisms, guiding future research for better early detection, prevention, and personalized treatment strategies for women affected by PPD and their families.

Postpartum depression: aetiology, pathogenesis and the role of nutrients and dietary supplements in prevention and management

Postpartum depression (PPD) is a challenging psychological disorder faced by 10-30% of mothers across the globe. In India, it occurs among 22% of mothers. Its aetiology and pathophysiology aren't fully understood as of today but multiple theories on the interplay of hormones, neurotransmitters, genetics, epigenetics, nutrients, socio-environmental factors, etc. exist. Nutrients are not only essential for the synthesis of neurotransmitters, but they may also indirectly influence genomic pathways that methylate DNA, and there is evidence for molecular associations between nutritional quality and psychological well-being. Increased behavioural disorders have been attributed to macro- and micronutrient deficiencies, and dietary supplementation has been effective in treating several neuropsychiatric illnesses. Nutritional deficiencies occur frequently in women, especially during pregnancy and breastfeeding. The aim of this study was to perform a comprehensive literature review of evidence-based research in order to identify, gather and summarize existing knowledge on PPD's aetiology, pathophysiology, and the role of nutrients in its prevention as well as management. The possible mechanisms of action of nutrients are also presented here. Study findings show that the risk of depression increases when omega-3 fatty acid levels are low. Both fish oil and folic acid supplements have been used to effectively treat depression. Antidepressant efficacy is lowered by folate insufficiency. Folate, vitamin B12, iron, etc. deficiencies are more prevalent in depressed people than in non-depressed people. Serum cholesterol levels and plasma tryptophan levels are found to be inversely correlated with PPD. Serum vitamin D levels were associated inversely with perinatal depression. These findings highlight the importance of adequate nutrition in the antepartum period. Given that nutritional therapies can be affordable, safe, simple to use, and are typically well-accepted by patients, more focus should be placed on dietary variables in PPD.

Risk Factors for Postpartum Depression Based on Genetic and Epigenetic Interactions

Postpartum depression (PPD) is a serious mood disorder that tends to occur after the delivery, which may bring lifelong consequences to women and their families in terms of family relationships, social relationships, and mental health. Currently, various risk factors including environmental factors and genetic factors that may induce postpartum depression have been extensively studied. In this review, we suggest that postpartum women's susceptibility to postpartum depression may be the result of the interaction between the genes associated with postpartum depression as well as the interaction between genetic and environmental factors. We reviewed the genes that have been studied in postpartum depression, including genes related to the synthesis, metabolism, and transport of monoamine neurotransmitters, key molecules of the HPA axis, and the kynurenine pathway. These studies have found more or less gene-gene and gene-environment interactions, so we will discuss these issues in more detail. However, so far, the conclusions of these risk factors, especially genetic factors, are not completely consistent in the occurrence and exacerbation of symptoms in postpartum depression, and it is not clear how these risk factors specifically participate in the pathological mechanism of the disease and play a role. We conclude that the role of genetic polymorphisms, including genetic and epigenetic processes, in the occurrence and development of postpartum depression, is complex and ambiguous. We also note that interactions between multiple candidate genes and the environment have been suggested as causes of depression, suggesting that more definitive research is needed to understand the heritability and susceptibility of PPD. Overall, our work supports the hypothesis that postpartum depression is more likely to be caused by a combination of multiple genetic and environmental factors than by a single genetic or environmental influence.

Exploration for biomarkers of postpartum depression based on metabolomics: A systematic review

BACKGROUND

Postpartum depression (PPD) is the most frequent psychiatric complication during the postnatal period and its mechanisms are not fully understood. Metabolomics, can quantitatively measure metabolites in a high-throughput method, and thus uncover the underlying pathophysiology of disease.

OBJECTIVES

In this study, we reviewed metabolomics studies conducted on PPD, aiming to understand the changes of metabolites in PPD patients and analyze the potential application of metabolomics in PPD prediction and diagnosis.

METHODS

Relevant articles were searched in PubMed, Google scholar, and Web of Science databases from January 2011 to July 2022. The metabolites involved were systematically examined and compared. MetaboAnalyst online software was applied to analyze metabolic pathways.

RESULTS

A total of 14 papers were included in this study. There were several highly reported metabolites, such as kynurenine, kynurenic acid, and eicosapentaenoic acid. Dysregulation of metabolic pathways involved amino acids metabolism, fatty acids metabolism, and steroids metabolism.

LIMITATIONS

The included studies are relatively inadequate, and further work is needed.

CONCLUSIONS

This study summarized significant metabolic alterations that provided clues for the prediction, diagnosis, and pathogenesis of PPD.

A pilot study of multilevel analysis of BDNF in paternal and maternal perinatal depression

Depression in the perinatal period is common in mothers worldwide. Emerging research indicates that fathers are also at risk of developing perinatal depression. However, knowledge regarding biological risk factors and pathophysiological mechanisms of perinatal depression is still scarce, particularly in fathers. It has been suggested that the neurotrophin BDNF may play a role in maternal perinatal depression; however, there is currently no data regarding paternal perinatal depression. For this pilot study, 81 expecting parents were recruited and assessed at several time points. We screened for depression using EPDS and MADRS, investigated several psychosocial variables, and took blood samples for BDNF val66met genotyping, epigenetic, and protein analysis. Between pregnancy and 12 months postpartum (pp), we found that 3.7 to 15.7% of fathers screened positive for depression, and 9.6 to 24% of mothers, with at least a twofold increased prevalence in both parents using MADRS compared with EPDS. We also identified several psychosocial factors associated with perinatal depression in both parents. The data revealed a trend that lower BDNF levels correlated with maternal depressive symptoms at 3 months pp. In the fathers, no significant correlations between BDNF and perinatal depression were found. Pregnant women demonstrated lower BDNF methylation and BDNF protein expression compared with men; however, these were found to increase postpartum. Lastly, we identified correlations between depressive symptoms and psychosocial/neurobiological factors. The data suggest that BDNF may play a role in maternal perinatal depression, but not paternal.

Sex steroids-induced neurogenesis in adult brain: a better look at mechanisms and mediators

Adult neurogenesis is the production of new nerve cells in the adult brain. Neurogenesis is a clear example of the neuroplasticity phenomenon which can be observed in most of mammalian species, including human beings. This phenomenon occurs, at least, in two regions of the brain: the subgranular zone of the dentate gyrus in hippocampus and the ventricular zone of lateral ventricles. Numerous studies have investigated the relationship between sex steroid hormones and neurogenesis of adult brain; of which, mostly concentrated on the role of estradiol. It has been shown that estrogen plays a significant role in this process through both classic and non-classic mechanisms, including a variety of different growth factors. Therefore, the objective of this review is to investigate the role of female sex steroids with an emphasis on estradiol and also its potential implications for regulating the neurogenesis in the adult brain.

Postpartum Depression: Current Status and Possible Identification Using Biomarkers

Postpartum depression (PPD) is a serious health issue that can affect about 15% of the female population within after giving birth. It often conveys significant negative consequences to the offsprings. The symptoms and risk factors are somewhat similar to those found in non-postpartum depression. The main difference resides in the fact that PPD is triggered by postpartum specific factors, including especially biological changes in the hormone levels. Patients are usually diagnosed using a questionnaire onsite or in a clinic. Treatment of PPD often involves psychotherapy and antidepressant medications. In recent years, there have been more researches on the identification of biological markers for PPD. In this review, we will focus on the current research status of PPD, with an emphasis on the recent progress made on the identification of PPD biomarkers.

Is Postpartum Depression Different From Depression Occurring Outside of the Perinatal Period? A Review of the Evidence

Whether a major depressive episode occurring in the postpartum period (i.e., postpartum depression [PPD]) is sufficiently distinct from major depressive episodes occurring at other times (i.e., major depressive disorder) to warrant a separate diagnosis is a point of debate with substantial clinical significance. The evidence for and against diagnostic distinction for PPD is reviewed with respect to epidemiology, etiology, and treatment. Overall, evidence that PPD is distinct from major depressive disorder is mixed and is largely affected by how the postpartum period is defined. For depression occurring in the early postpartum period (variably defined, but typically with onset in the first 8 weeks), symptom severity, heritability, and epigenetic data suggest that PPD may be distinct, whereas depression occurring in the later postpartum period may be more similar to major depressive disorder occurring outside of the perinatal period. The clinical significance of this debate is considerable given that PPD, the most common complication of childbirth, is associated with immediate and enduring adverse effects on maternal and offspring morbidity and mortality. Future research investigating the distinctiveness of PPD from major depressive disorder in general should focus on the early postpartum period when the rapid decline in hormones contributes to a withdrawal state, requiring profound adjustments in central nervous system function.

Association between serum BDNF levels and maternal perinatal depression: A review: Special Section on "Translational and Neuroscience Studies in Affective Disorders" Section Editor, Maria Nobile MD, PhD

INTRODUCTION

A large amount of studies demonstrated reduced serum Brain-Derived Neurotrophic Factor (BDNF) levels in stress-related and depressive disorders. However, it is still unclear if a similar deficit in BDNF concentrations might also characterize maternal perinatal depression.

METHODS

We performed a bibliographic search on PUBMED of all the studies investigating the association between maternal BDNF levels and perinatal depression. The inclusion criteria were met by thirteen studies.

RESULTS

Overall, the majority of the studies reported a significant reduction in serum BDNF levels among depressed mothers compared to healthy mothers either during pregnancy or in the postpartum period. Moreover, some studies also demonstrated that the BDNF reduction could be more evident in those depressed mothers with perinatal stressful life events and suicide risk.

LIMITATIONS

BDNF were collected at different time points across the studies. Potential confounding factors, including the clinical characteristics of the samples employed by the original studies, might have influenced the results.

CONCLUSIONS

So far, the evidences suggested the presence of decreased BDNF concentrations in perinatal depressive disorders. However, further studies are needed in order to confirm the role of BDNF in this disorder.

Stress-related genetic polymorphisms in association with peripartum depression symptoms and stress hormones: A longitudinal population-based study

Individual differences in the response of the stress system to hormonal changes during pregnancy and the postpartum period render some women susceptible to developing depression. The present study sought to investigate peripartum depression and stress hormones in relation to stress-related genotypes. The Edinburgh Postnatal Depression Scale was used to assess peripartum depressive symptoms in a sample of 1629 women, followed from pregnancy week seventeen to six months postpartum. Genotypes of ninety-four haplotype-tag single nucleotide polymorphisms (SNPs) in sixteen genes of the hypothalamus-pituitary-adrenal axis pathway were analyzed and data on psychosocial and demographic factors was collected. In sub-studies, salivary cortisol awakening response in gestational week 35-39, salivary evening cortisol levels in gestational week 36 and postpartum week 6, and blood cortisol and cortisone levels in gestational week 35-39 were analyzed. SNP-set kernel association tests were performed at the gene-level, considering psychosocial and demographic factors, followed by post-hoc analyses of SNPs of significant genes. Statistically significant findings at the 0.05 p-level included SNPs in the hydroxysteroid 11-beta dehydrogenase 1 (HSD11B1) gene in relation to self-rated depression scores in postpartum week six among all participants, and serpin family A member 6 (SERPINA6) gene at the same time-point among women with de novo onset of postpartum depression. SNPs in these genes also associated with stress hormone levels during pregnancy. The present study adds knowledge to the neurobiological basis of peripartum depression by systematically assessing SNPs in stress-regulatory genes and stress-hormone levels in a population-based sample of women.

Pathophysiological mechanisms implicated in postpartum depression

This review aims to summarize the diverse proposed pathophysiological mechanisms contributing to postpartum depression, highlighting both clinical and basic science research findings. The risk factors for developing postpartum depression are discussed, which may provide insight into potential neurobiological underpinnings. The evidence supporting a role for neuroendocrine changes, neuroinflammation, neurotransmitter alterations, circuit dysfunction, and the involvement of genetics and epigenetics in the pathophysiology of postpartum depression are discussed. This review integrates clinical and preclinical findings and highlights the diversity in the patient population, in which numerous pathophysiological changes may contribute to this disorder. Finally, we attempt to integrate these findings to understand how diverse neurobiological changes may contribute to a common pathological phenotype. This review is meant to serve as a comprehensive resource reviewing the proposed pathophysiological mechanisms underlying postpartum depression.

Gene-environment interactions between stress and 5-HTTLPR in depression: A meta-analytic update

BACKGROUND

Meta-analyses have yielded contradictory findings concerning the role of 5-HTTLPR in interaction with stress (GxE) in depression. The current meta-analysis investigates if these contradictory findings are a result of differences between studies in methodological approaches towards the assessment of stress and depression.

METHODS

After performing a systematic database search (February to December 2016), first, a meta-analysis was used to investigate the total effect size and publication bias. Second, stratified meta-analyses were used to investigate the potential moderating influence of different methodological approaches on heterogeneity of study findings. Third, a meta-regression was used to investigate the combined influence of the methodological approaches on the overall effect size.

RESULTS

Results showed a small but significant effect of 5-HTTLPR in interaction with stress in the prediction of depression (OR[95%CI] = 1.18[1.09; 1.28], n = 48 effect sizes from 51 studies, totaling 51,449 participants). There was no evidence of publication bias. Heterogeneity of effect sizes was a result of outliers and not due to different methodological approaches towards the assessment of stress and depression. Yet, there was some evidence that studies adopting a categorical and interview approach to the assessment of stress report higher GxE effects, but further replication of this finding is needed.

LIMITATIONS

A large amount of heterogeneity (i.e., 46%) was not explained by the methodological factors included in the study and there was a low response rate of invited studies.

CONCLUSIONS

The current meta-analysis provides new evidence for the robustness of the interaction between stress and 5-HTTLPR in depression.

Hormonal Regulation of Hippocampal Neurogenesis: Implications for Depression and Exercise

Adult hippocampal neurogenesis exists in all mammalian species, including humans, and although there has been considerable research investigating the function and regulation of neurogenesis, there remain many open questions surrounding the complexity of this phenomenon. This stems partially from the fact that neurogenesis is a multistage process that involves proliferation, differentiation, migration, survival, and eventual integration of new cells into the existing hippocampal circuitry, each of which can be independently influenced. The function of adult neurogenesis in the hippocampus is related to stress regulation, behavioral efficacy of antidepressants, long-term spatial memory, forgetting, and pattern separation. Steroid hormones influence the regulation of hippocampal neurogenesis, stress regulation, and cognition and differently in males and females. In this chapter, we will briefly tap into the complex network of steroid hormone modulation of neurogenesis in the hippocampus with specific emphasis on stress, testosterone, and estrogen. We examine the possible role of neurogenesis in the etiology of depression and influencing treatment by examining the influence of both pharmacological (selective serotonin reuptake inhibitors, tricyclic antidepressants) treatments and non-pharmacological (exercise) remedies.

Seasonality and BDNF polymorphism influences depression outcome in patients with atopic dermatitis and psoriasis

OBJECTIVES

To examine the effect of seasonality and rs6265 genotype on depression outcome and brain-derived neurotrophic factor (BDNF) level with dermatitis patients from onset through remission.

METHODS

Atopic dermatitis (AD, 56) and psoriasis (PS, 33) patients and healthy controls (HC, 49) were recruited over the 2014 calendar year. Patients were subdivided by immunoglobulin E (IgE) sensitivity (AD only), season and rs6265 genotype. Assessments were performed at onset and week 10 (Hamilton Depression Rating Scale [HAM-D], SCORAD/PASI, IgE, BDNF). Patients received standard corticosteroid and antihistamine interventions.

RESULTS

All patients responded to corticosteroid treatment. Seasonally differential outcomes were observed in all groups. HAM-D was elevated at onset and improved over 10 weeks: AD cohort 1 (autumn/winter, AD-1) patients improved and AD cohort 2 (spring/summer, AD-2) patients remained elevated. BDNF levels were elevated in AD and seasonal differential: AD-2 declined at 10 weeks, whereas AD-1 remained high (intrinsic AD) or elevated further (extrinsic AD). PS cohort 2 declined to below control at 10 weeks. AD Val/Val had persistently elevated HAM-D and AD Val/Met were either normal (AD-1) or persistently elevated (AD-2).

CONCLUSIONS

Findings presented here suggest a strong influence of seasonality on depression outcome and BDNF expression in AD and PS and likely reflect separate patient populations which differentially respond to environment-based stressors.

Sex differences in depression during pregnancy and the postpartum period

Women have a lifetime risk of major depression double that of men but only during their reproductive years. This sex difference has been attributed partially to activational effects of female sex steroids and also to the burdens of pregnancy, childbirth, and parenting. Men, in contrast, have a reproductive period difficult to delineate, and research on the mental health of men has rarely considered the effects of fatherhood. However, the couple goes through a number of potentially stressing events during the reproductive period, and both mothers and fathers are at risk of developing peripartum depression. This Review discusses the literature on maternal and paternal depression and the endocrine changes that may predispose a person to depression at this stage of life, with specific focus on the hypothalamus–pituitary axis, oxytocin, and testosterone levels in men. Important findings on sex differences in the neural correlates of maternal and paternal behavior have emerged, highlighting the relevance of the emotional brain in mothers and the sociocognitive brain in fathers and pointing toward the presence of a common parents' brain. Additionally, sex differences in neurogenesis and brain plasticity are described in relation to peripartum depression. © 2016 The Authors. Journal of Neuroscience Research Published by Wiley Periodicals, Inc.

Reproductive Affective Disorders: a Review of the Genetic Evidence for Premenstrual Dysphoric Disorder and Postpartum Depression

PURPOSE OF REVIEW

The purpose of this study is to review and summarize the literature exploring the genetic basis for premenstrual dysphoric disorder (PMDD) and postpartum depression (PPD).

RECENT FINDINGS

There is more evidence for a genetic basis for PPD than for PMDD, but only when PPD is defined as beginning in the immediate postpartum time period. Familial, genome-wide linkage and association studies, and candidate gene studies, most in the past 10 years, have examined the genetic etiology of reproductive affective disorders, including PMDD and PPD. The most commonly studied genes include SERT, COMT, MAOA, BDNF, and ESR1 and 2. This qualitative review of the recent literature finds limited evidence so far for the genetic basis for PMDD, with both familial and candidate gene studies having negative or conflicting results. Evidence is stronger for the genetic basis for PPD, with positive associations found in family studies and in several genes associated with major depression as well as genes involved in estrogen signaling but only when PPD onset is shortly after delivery. Epigenetic biomarkers on genes responsive to estrogen have also been found to predict PPD. Our findings underscore the need for additional studies with larger samples, as well as the crucial importance of timing in the definition of PPD for genetic studies.

Associations between a polymorphism in the hydroxysteroid (11-beta) dehydrogenase 1 gene, neuroticism and postpartum depression

BACKGROUND

This study examined the association between a single nucleotide polymorphism in the hydroxysteroid (11-beta) dehydrogenase 1 gene and neuroticism, as well as the possible mediatory role of neuroticism in the association between the polymorphism and postpartum depressive symptoms.

METHODS

769 women received questionnaires containing the Edinburgh Postnatal Depression Scale (EPDS) at six weeks postpartum and demographic data at pregnancy week 17 and 32 and at six weeks postpartum, as well as the Swedish universities Scales of Personality at pregnancy week 32.

RESULTS

Linear regression models showed an association between the GG genotype and depressive symptoms. When neuroticism was introduced in the model, it was associated with EPDS score, whereas the association between the GG genotype and EPDS became borderline significant. A path analysis showed that neuroticism had a mediatory role in the association between the polymorphism and EPDS score.

LIMITATIONS

The use of the EPDS, which is a self-reporting instrument.

CONCLUSIONS

Neuroticism was associated with the polymorphism and had a mediatory role in the association between the polymorphism and postpartum depression. This finding elucidates the genetic background of neuroticism and postpartum depression.

Serum BDNF concentration after delivery is associated with development of postpartum depression: A 3-month follow up study

BACKGROUND

Our aim was to determine whether there is a relationship between serum brain-derived neurotrophic factor (BDNF) and postpartum depression (PPD) in a cohort Chinese population.

METHODS

From May 1, 2014, to September 30, 2014, all eligible women not on medication for depression giving birth at the Fourth Affiliated Hospital of Harbin Medical University were consecutively recruited and followed up for 3 months. At 3 months postpartum, women were screened for depression using the Edinburgh Postnatal Depression Scale (EPDS). The primary outcome measure was an EPDS score of > or =12. Enzyme-linked immunosorbent assay (ELISA) was used to measure serum levels of BDNF at admission. Multivariate analyses were performed using logistic regression models.

RESULTS

During the study period, 340 women were enrolled and completed follow-up. In those women, 37 women (10.9%) were considered as meeting criteria for PPD. Serum BDNF levels in women without PPD were significantly higher than those in women with PPD (P<0.0001). Based on the ROC curve, the optimal cutoff value of serum BDNF levels as an indicator for screening of PPD was estimated to be 12.0ng/ml, which yielded a sensitivity of 82.8% and a specificity of 72.6%, with the area under the curve at 0.809 (95%CI, 0.731-0.887). In multivariate analysis, there was an increased risk of PPD associated with BDNF levels ≤12.0ng/ml (OR 7.243, 95% CI: 3.883-12.746; P<0.0001) after adjusting for possible confounders.

CONCLUSION

The present study demonstrates a strong relationship between reduced serum BDNF levels at admission and the development of PPD within the 3 months.

Early predictors of behavioural problems in pre-schoolers - a longitudinal study of constitutional and environmental main and interaction effects

Background

The early environment is important for child development and wellbeing. Gene-by-environment studies investigating the impact of the serotonin transporter gene-linked polymorphic region (5-HTTLPR) and the Brain Derived Neurotrophic Factor (BDNF) Val66Met polymorphisms by life events on mental health and behaviour problems have been inconclusive. Methodological differences regarding sample sizes, study population, definitions of adversities and measures of mental health problems obstacle their comparability. Furthermore, very few studies included children. The aim of this study was to examine the associations between a broad range of risk factors covering pregnancy and birth, genetic polymorphism, experience of multiple life events and psychosocial environment, and child behaviour at age 3, using a comparably large, representative, population-based sample.

Methods

A total of 1,106 children, and their mothers, were followed from pregnancy to age 3. Information on pregnancy and birth-related factors was retrieved from the Medical Birth Register. Questionnaires on depressive symptoms, child behaviour and child experiences of life events were filled in by the mothers. Child saliva samples were used for genotyping the 5-HTTLPR and BDNF Val66Met polymorphisms. Multiple logistic regression was used to investigate the association between psychological scales and genetic polymorphisms.

Results

Symptoms of postpartum depression increased the risk of both internalizing and externalizing problems. Experience of multiple life events was also a predictor of behavioural problems across the scales. No gene-by-environment or gene-by-gene-by-environment interactions were found. Children of immigrants had an increased risk of internalizing problems and parental unemployment was significantly associated with both internalizing and externalizing type of problems.

Conclusion

This study shows the importance of the psychosocial environment for psychosocial health in preschool children, and adds to the literature of null-findings of gene-by-environment effects of 5-HTTLPR and BDNF in children.

Electronic supplementary material

The online version of this article (doi:10.1186/s12887-016-0614-x) contains supplementary material, which is available to authorized users.

Effect of curcumin on serum brain-derived neurotrophic factor levels in women with premenstrual syndrome: A randomized, double-blind, placebo-controlled trial

Premenstrual syndrome (PMS) is a variety of physical, mental, and behavioral symptoms that start during the late luteal phase of the menstrual cycle, and the symptoms disappear after the onset of menses. Serum brain-derived neurotrophic factor (BDNF) levels during luteal phase in women associated with PMS have more alterations than women not suffering from PMS. In this regard, altered luteal BDNF levels in women with PMS might play a role in a set of psychological and somatic symptoms of the PMS. Studies of last decade revealed neuroprotective effects of curcumin and its ability to increase BDNF levels. In the present study, we evaluated the effect of curcumin on serum BDNF level and PMS symptoms severity in women with PMS. Present study is a Randomized, Double-Blinded, Placebo-Controlled Clinical Trial. Curcumin treatment was given for three successive menstrual cycles and each cycle ran 10 days. After having identified persons with PMS, participants were randomly allocated into placebo (n=35) and curcumin (n=35) groups. Each sample in placebo and curcumin groups received two capsules daily for seven days before menstruation and for three days after menstruation for three successive menstrual cycles. Participants noted the severity of the symptoms mentioned in the daily record questionnaire. Self-report was used to determine menstrual cycle phase of participants. At the fourth day of each menstrual cycle venous blood samples were collected for BDNF measurement by ELISA method. Before intervention, BDNF levels and mean scores of PMS symptoms (mood, behavioral and physical symptoms) between two groups showed no significant differences. But in curcumin group first, second and third cycles after interventions BDNF levels were significantly higher and mean scores of PMS symptoms were significantly less than placebo group. Based on our results part of these beneficial effects of curcumin may be mediated through enhancing serum BDNF levels in women with PMS.

Perinatal Major Depression Biomarkers: A systematic review

Postpartum depression, now termed perinatal depression by the DSM-5, is a clinically relevant disorder reaching 15% of incidence. Although it is quite frequent and associated with high social dysfunction, only recently its underpinning biological pathways have been explored, while multiple and concomitant risk factors have been identified (e.g. psychosocial stress). Peripartum depression usually has its onset during the third trimester of pregnancy or in the postpartum, being one of the most common medical complications in new mothers. Purpose of the present review is to summarize the state of art of biological biomarkers involved in the pathogenesis of perinatal depression, in view of the fact that suboptimal prenatal milieu can induce permanent damage in subsequent offspring life and have a negative impact on mother-child relationship. Furthermore, parents' biological changes due to medical/psychiatric disorders or stress exposure could influence offspring life: a concept known as 'intergenerational transmission', acting by variations into gametes and the gestational uterine environment. Given the evidence that perinatal mental disorders involve risks for the mother and offspring, the search for reliable biomarkers in high-risk mothers actually represents a medical priority to prevent perinatal depression.

Brain Reward Pathway Dysfunction in Maternal Depression and Addiction: A Present and Future Transgenerational Risk

Two research areas that could benefit from a greater focus on the role of the reward pathway are maternal depression and maternal addiction. Both depression and addiction in mothers are mediated by deficiencies in the reward pathway and represent substantial risks to the health of offspring and future generations. This targeted review discusses maternal reward deficits in depressed and addicted mothers, neural, genetic, and epigenetic mechanisms, and the transgenerational transmission of these deficits from mother to offspring. Postpartum depression and drug use disorders may entail alterations in the reward pathway, particularly in striatal and prefrontal areas, which may affect maternal attachment to offspring and heighten the risk of transgenerational effects on the oxytocin and dopamine systems. Alterations may involve neural circuitry changes, genetic factors that impact monoaminergic neurotransmission, as well as growth factors such as BDNF and stress-associated signaling in the brain. Improved maternal reward-based preventative measures and treatments may be specifically effective for mothers and their offspring suffering from depression and/or addiction.

Effect of Telephone-Based Support on Postpartum Depression: A Randomized Controlled Trial

Background

Postpartum depression (PPD) is one public health issue that affects both maternal and child health. This research studies the effect of health volunteers’ telephone- based support on decreasing PPD.

Materials and Methods

This randomized controlled trial evaluated 203 women who had uncomplicated deliveries. The women completed the Edinburg Postnatal Depres- sion Scale (EPDS), 10 to 15 days after childbirth in order to be assessed for pre-trial depression scores. The cut-off point for depression was considered to be a score of >10. We randomly assigned 54 eligible mothers (n=27 per group) with mild and moderate de- pression to the intervention and control groups. In both groups, mothers received routine postpartum care. The intervention group additionally received telephone support from health volunteers. A questionnaire was used to gather demographic and obstetric infor- mation. By the end of the 6thweek, mothers completed the EPDS to be reassessed for depression after intervention. Data were analyzed using the chi-square, Fisher’s exact, t- and paired t tests.

Results

The mean depression scores before intervention (10 to 15 days after childbirth) in the intervention and control groups did not significantly differ (P=0.682). Depres- sion scores of the intervention and control groups showed a significant difference after 6 weeks (P=0.035). In addition, there was a significant decrease in depression for the intervention and control groups (P=0.045).

Conclusion

Health volunteer telephone-based support effectively decreased PPD and may be beneficial to women with symptoms of mild and moderate PPD (Registration number: IRCT201202159027N1).

Gender-linked stem cell alterations in stroke and postpartum depression

Stroke is a significant unmet clinical need. The current stroke treatment of tissue plasminogen activator is limited to the very acute 4.5 h after disease onset which benefits only less than 3% of ischemic stroke patients. Our overarching hypothesis advances the notion that gender, which has been established as a comorbidity factor of stroke, plays a key role in regenerative medicine, in particular stem cell therapy. We hypothesize that gender is a key factor in culture-induced stemness of adult stem cells. Our goal is to provide new evidence supporting gender effects on stroke and stem cells for the purpose of enhancing our understanding of the pathophysiology of the disease and developing novel stem cell-based therapeutics targeting gender-relevant stress hormones as manifested in a stroke-postpartum depression paradigm.

Postpartum depression: A systematic review of the genetics involved

Postpartum depression is one of the most prevalent psychopathologies. Its prevalence is estimated to be between 10% and 15%. Despite its multifactorial etiology, it is known that genetics play an important role in the genesis of this disorder. This paper reviews epidemiological evidence supporting the role of genetics in postpartum depression (PPD). The main objectives of this review are to determine which genes and polymorphisms are associated with PPD and discuss how this association may occur. In addition, this paper explores whether these genes are somehow related to or even the same as those linked to Major Depression (MD). To identify gaps in the current knowledge that require investigation, a systematic review was conducted in the electronic databases PubMed, LILACS and SciELO using the index terms “postpartum depression” and “genetics”. Literature searches for articles in peer-reviewed journals were made until April 2014. PPD was indexed 56 times with genetics. The inclusion criteria were articles in Portuguese, Spanish or English that were available by institutional means or sent by authors upon request; this search resulted in 20 papers. Genes and polymorphisms traditionally related to MD, which are those involved in the serotonin, catecholamine, brain-derived neurotrophic factor and tryptophan metabolism, have been the most studied, and some have been related to PPD. The results are conflicting and some depend on epigenetics, which makes the data incipient. Further studies are required to determine the genes that are involved in PPD and establish the nature of the relationship between these genes and PPD.

The Influence of genetic factors on peripartum depression: A systematic review

BACKGROUND

This systematic review aimed to explore the potential influence of genetic factors on the symptoms of peripartum depression and to critically analyze the methodologies employed by the examined studies.

METHODS

A systematic review of the literature indexed prior to July 2014 identified 200 articles. After applying the inclusion and exclusion criteria, 39 papers were included.

RESULTS

The papers predominantly featured a molecular genetic approach (n=35), and the majority examined polymorphisms (n=27). Most studies used samples of Caucasians living in high income countries. The results suggest that the influence of genetic factors become more consistent when methodological variations among the studies are considered. Environmental stressors are also important variables that influence the relationship between genetic factors and peripartum depressive states. In addition, differences in the influence of genetic factors were observed depending upon the precise time point during pregnancy or the postpartum period that was examined in the studies. The late stages of pregnancy and the early postpartum period were times of greater genetic vulnerability.

LIMITATIONS

This study was limited by the small number of papers reviewed and by the lack of information regarding whether the effects of genetics on peripartum depression are specific to certain ethnicities and/or stressors.

CONCLUSIONS

Genetic studies of perinatal depression reinforce a pathophysiological role of the hormonal changes inherent in the childbirth period. However, the distinction between depressive episodes that begin during pregnancy from those that begin during the postpartum period can still be useful to improve our understanding of the physiopathology of depressive disorders.

The role of reproductive hormones in postpartum depression

Despite decades of research aimed at identifying the causes of postpartum depression (PPD), PPD remains common, and the causes are poorly understood. Many have attributed the onset of PPD to the rapid perinatal change in reproductive hormones. Although a number of human and nonhuman animal studies support the role of reproductive hormones in PPD, several studies have failed to detect an association between hormone concentrations and PPD. The purpose of this review is to examine the hypothesis that fluctuations in reproductive hormone levels during pregnancy and the postpartum period trigger PPD in susceptible women. We discuss and integrate the literature on animal models of PPD and human studies of reproductive hormones and PPD. We also discuss alternative biological models of PPD to demonstrate the potential for multiple PPD phenotypes and to describe the complex interplay of changing reproductive hormones and alterations in thyroid function, immune function, hypothalamic-pituitary-adrenal (HPA) axis function, lactogenic hormones, and genetic expression that may contribute to affective dysfunction. There are 3 primary lines of inquiry that have addressed the role of reproductive hormones in PPD: nonhuman animal studies, correlational studies of postpartum hormone levels and mood symptoms, and hormone manipulation studies. Reproductive hormones influence virtually every biological system implicated in PPD, and a subgroup of women seem to be particularly sensitive to the effects of perinatal changes in hormone levels. We propose that these women constitute a "hormone-sensitive" PPD phenotype, which should be studied independent of other PPD phenotypes to identify underlying pathophysiology and develop novel treatment targets.

Brain derived neurotrophic factor gene (BDNF) and personality traits: the modifying effect of season of birth and sex

Personality traits are complex phenotypes influenced by interactions of multiple genetic variants of small effect and environmental factors. It has been suggested that the brain derived neurotrophic factor gene (BDNF) is involved in personality traits. Season of birth (SOB) has also been shown to affect personality traits due to its influences on brain development during prenatal and early postnatal periods. The present study aimed to investigate the effects of BDNF on personality traits; and the modifying effects of SOB and sex on associations between BDNF and personality traits. A sample of 1018 young adults (68% women; age range 17-25years) of Caucasian origin from the Russian Federation was assessed on personality traits (Novelty Seeking, Harm Avoidance, Reward Dependence, Persistence, Self-directedness, Cooperativeness, Self-transcendence) with the Temperament and Character Inventory-125 (TCI-125). Associations between personality traits and 12 BDNF SNPs were tested using linear regression models. The present study demonstrated the effect of rs11030102 on Persistence in females only (PFDR=0.043; r(2)=1.3%). There were significant interaction effects between Val66Met (rs6265) and SOB (PFDR=0.048, r(2)=1.4%), and between rs2030323 and SOB (PFDR=0.042, r(2)=1.3%), on Harm Avoidance. Our findings provide evidence for the modifying effect of SOB on the association between BDNF and Harm Avoidance, and for the modifying effect of sex on the association between BDNF and Persistence.

Biological and psychosocial predictors of postpartum depression: systematic review and call for integration

Postpartum depression (PPD) adversely affects the health and well being of many new mothers, their infants, and their families. A comprehensive understanding of biopsychosocial precursors to PPD is needed to solidify the current evidence base for best practices in translation. We conducted a systematic review of research published from 2000 through 2013 on biological and psychosocial factors associated with PPD and postpartum depressive symptoms. Two hundred fourteen publications based on 199 investigations of 151,651 women in the first postpartum year met inclusion criteria. The biological and psychosocial literatures are largely distinct, and few studies provide integrative analyses. The strongest PPD risk predictors among biological processes are hypothalamic-pituitary-adrenal dysregulation, inflammatory processes, and genetic vulnerabilities. Among psychosocial factors, the strongest predictors are severe life events, some forms of chronic strain, relationship quality, and support from partner and mother. Fully integrated biopsychosocial investigations with large samples are needed to advance our knowledge of PPD etiology.

An update on the interaction between the serotonin transporter promoter variant (5-HTTLPR), stress and depression, plus an exploration of non-confirming findings

In the three years since the most recent meta-analysis of the association between the serotonin transported promoter polymorphism (5-HTTLPR), stress and the development of depression, another 27 studies have been published on this issue, which is an increase of 50% more studies than were previously reviewed. In addition, previous findings of inconsistency of results across studies argued for further exploration of this relationship. From the 81 studies identified to June 2013, the significant relationship between the short form of the 5-HTTLPR was confirmed (p=.0000009), which is stronger than the relationship reported in the most recent meta-analysis in 2011. However, nearly 26% of the 81 studies reviewed failed to show any significant association between the 5-HTTLPR, stress and depression, and four studies found opposite results to those expected. Examination of the methodologies of all studies failed to indicate any flaws in the opposite or unequivocal studies, and the latter had larger sample sizes than those studies which supported the expected association, arguing that the null results were not an outcome of insufficient statistical power. The need to consider aspects of samples and measures of depression, particularly the presence of subtypes of depression in future research is discussed.

Experience of the first breastfeeding session in association with the use of the hands-on approach by healthcare professionals: a population-based Swedish study

OBJECTIVE

The aim of this study was to investigate the prevalence of healthcare professionals' use of the hands-on approach during the first breastfeeding session postpartum and its possible association with the mothers' experience of their first breastfeeding session.

MATERIALS AND METHODS

This was a population-based longitudinal study conducted at Uppsala University Hospital, Uppsala, Sweden, of all women giving birth at the hospital from May 2006 to June 2007. Six months postpartum, a questionnaire including questions regarding breastfeeding support, caregiving routines, depressive symptoms, and the woman's experience of the first breastfeeding session was sent to the mothers. The main outcome measures were use of the hands-on approach during the first breastfeeding session and the mother's experience of the breastfeeding session.

RESULTS

In total, 879 women participated in the study. Thirty-eight percent of the women received the hands-on approach during the first breastfeeding session. High body mass index, primiparity, and having the first breastfeeding session postponed were all independently associated with the hands-on approach. Women who received the hands-on approach were more likely to report a negative experience of the first breastfeeding session (odds ratio=4.48; 95% confidence interval, 2.57-7.82), even after adjustment for possible confounders (odds ratio=2.37; 95% confidence interval, 1.02-5.50).

CONCLUSIONS

This study indicates that the hands-on approach is commonly used during the first breastfeeding session and is associated with a more negative experience of the first breastfeeding session. Consequently, caregivers need to question the use of this method, and further research about breastfeeding support is required.

Levels of brain derived neurotrophic factors across gestation in women with preeclampsia

Preeclampsia (PE) is a major pregnancy complication of placental origin which leads to adverse pregnancy outcome. Brain derived neurotrophic factor (BDNF) is suggested to promote trophoblast growth and regulate placental and fetal development. This study for the first time examines the levels of maternal plasma BDNF at various time points during gestation, cord plasma and placental BDNF levels and their association with birth outcome in women with PE. Normotensive control (NC) women (n=89) and women with PE (n=61) were followed at three different time points [16-20 weeks (T1), 26-30 weeks (T2) and at delivery (T3)]. Maternal blood at all time points and cord blood was collected. Results indicate that maternal BDNF levels at T1 (p=0.050) and T3 (p=0.025) were lower in women with PE than in NC women. Cord BDNF levels at delivery in women with PE were lower (p=0.032) than those in NC women. Placental BDNF gene expression was also lower (p=0.0082) in women with PE than in NC women. Our data suggests that BDNF plays an important role in the development of the materno-fetal-placental unit during pregnancy. Alteration in the levels of BDNF during pregnancy may be associated with an abnormal development of the placenta resulting in PE.

The role of brain-derived neurotrophic factor in comorbid depression: possible linkage with steroid hormones, cytokines, and nutrition

Increasing evidence demonstrates a connection between growth factor function (including brain-derived neurotrophic factor, BDNF), glucocorticoid levels (one of the steroid hormones), and the pathophysiology of depressive disorders. Because both BDNF and glucocorticoids regulate synaptic function in the central nervous system, their functional interaction is of major concern. Interestingly, alterations in levels of estrogen, another steroid hormone, may play a role in depressive-like behavior in postpartum females with fluctuations of BDNF-related molecules in the brain. BDNF and cytokines, which are protein regulators of inflammation, stimulate multiple intracellular signaling cascades involved in neuropsychiatric illness. Pro-inflammatory cytokines may increase vulnerability to depressive symptoms, such as the increased risk observed in patients with cancer and/or autoimmune diseases. In this review, we discuss the possible relationship between inflammation and depression, in addition to the cross-talk among cytokines, BDNF, and steroids. Further, since nutritional status has been shown to affect critical pathways involved in depression through both BDNF function and the monoamine system, we also review current evidence surrounding diet and supplementation (e.g., flavonoids) on BDNF-mediated brain functions.

Three-way interaction effect of 5-HTTLPR, BDNF Val66Met, and childhood adversity on depression: a replication study

Both the serotonin transporter linked promoter region (5-HTTLPR) and the brain-derived neurotrophic factor (BDNF) Val66Met polymorphisms have been shown to interact with unfavourable environment in relation to depression symptoms and to depression diagnosis. Several attempts have been made to study a three-way interaction effect of these factors on depression, however with contradictory results. We aimed to test the hypothesis of a three-way interaction effect and to attempt at replication in an independent population-based sample. Family maltreatment, sexual abuse and depression were self-reported by an adolescent population-based cohort (N=1393) from the county of Västmanland, Sweden. DNA was isolated from saliva, and used for genotyping of the 5-HTTLPR and BDNF Val66Met polymorphisms. Neither 5-HTTLPR or BDNF genotypes separately, nor in interaction with each other had any relation to depression, however in an environment adjusted model a two-way interaction and a three-way interaction effect was found. Both 5-HTTLPR and BDNF Val66Met interacted with unfavourable environment in relation to depressive symptoms (Adj R²=0.19). Depressive symptoms and depression were more common among carriers of either the ss/sl+Val/Val or the ll+Met genotypes in the presence of early-life adversities. This three-way effect was more pronounced among girls. The current study, with a virtually similar set-up compared to previous studies, can partially confirm previous findings and their generalizability. The study also shows the importance of genetic plasticity in individuals with different environmental exposure, for different phenotypic expression.

Adipocytokines levels at delivery, functional variation of TFAP2β, and maternal and neonatal anthropometric parameters

OBJECTIVE

Adipocytokines participate in the regulation of glucose metabolism and fetal development. The transcription factor activating protein 2B (TFAP2β) has been associated with adipocytokine regulation, and gene variations with type 2 diabetes and obesity. This study investigated associations between maternal TFAP2B variation, adipocytokine levels, and maternal and neonatal anthropometric characteristics.

DESIGN AND METHODS

A population-based sample of women was followed from delivery to 6 months postpartum. Adiponectin, leptin, and interleukin-6 levels at delivery, and maternal as well as neonatal anthropometric variables were assessed. The TFAP2β intron 1 variable number tandem repeat (VNTR) was genotyped.

RESULTS

Maternal interleukin-6 correlated positively with leptin at delivery, with peripartum weight changes and weight of newborn males, adjusted for potential confounders. Leptin at delivery was associated with TFAP2β intron 1 VNTR genotype, adjusted for confounders, maternal weight and negatively with birth weight among female neonates. A path model suggested a link between TFAP2β genotype, leptin levels, and newborn females' weight.

CONCLUSIONS

The present results stress a role for the TFAP2 β in adiposity-related conditions and intrauterine growth. The association between neonatal birth weight and maternal adipocytokine levels, together with the observed sex effect, call for further studies on the mechanisms behind neuroendocrine fetal programming.

Biological aspects of postpartum depression

In comparison with the vast epidemiological literature on postpartum depression (PPD), relatively few studies have examined the biological aspects of the disorder. However, research into the biological mechanisms of PPD is a challenging task, as normal pregnancy and the postpartum period cause adaptive endocrine changes, which would otherwise be considered pathological in nonpregnant women. This review focuses on the adaptive changes of childbearing and nursing, which ultimately may put women at increased risk of PPD. In light of the normal physiology, the authors also attempt to describe the current evidence of the biological changes associated with the development of depression in the postpartum period, including ovarian steroids, the hypothalamic-pituitary-adrenal axis, the serotonergic neurotransmitter system, the thyroid system and inflammatory markers. In addition, current knowledge on candidate genes associated with PPD is reviewed.

Effect of gene, environment and maternal depressive symptoms on pre-adolescence behavior problems - a longitudinal study

BACKGROUND

Depression is a common and disabling condition with a high relapse frequency. Maternal mental health problems and experience of traumatic life events are known to increase the risk of behavior problems in children. Recently, genetic factors, in particular gene-by-environment interaction models, have been implicated to explain depressive etiology. However, results are inconclusive.

METHODS

Study participants were members of the SESBiC-study. A total of 889 mothers and their children were followed during the child's age of 3 months to 12 years. Information on maternal depressive symptoms was gathered postpartum and at a 12 year follow-up. Mothers reported on child behavior and traumatic life events experienced by the child at age 12. Saliva samples were obtained from children for analysis of 5-HTTLPR and BDNF Val66Met polymorphisms.

RESULTS

Multivariate analysis showed a significant association between maternal symptoms of depression and anxiety, and internalizing problems in 12-year-old children (OR 5.72, 95% CI 3.30-9.91). Furthermore, carriers of two short alleles (s/s) of the 5-HTTLPR showed a more than 4-fold increased risk of internalizing problems at age 12 compared to l/l carriers (OR 4.73, 95% CI 2.14-10.48). No gene-by-environment interaction was found and neither depressive symptoms postpartum or traumatic experiences during childhood stayed significant in the final model.

CONCLUSIONS

Concurrent maternal symptoms of depression and anxiety are significant risk factors for behavior problems in children, which need to be taken into account in clinical practice. Furthermore, we found a main effect of 5-HTTLPR on internalizing symptoms in 12-year-old children, a finding that needs to be confirmed in future studies.