Stressful life events and the serotonin transporter gene (5-HTT) in recurrent clinical depression

A Systematic Review of Resilience in At-Risk Youth for Psychotic Disorders: An Analysis of Protective and Risk Factors from Recent Literature

Psychotic disorders in youth pose significant challenges for mental health services, necessitating a detailed understanding of the interplay between risk factors and resilience. This systematic review aimed to assess how resilience factors might buffer the adverse effects of risk factors on the development of psychosis among youth, thereby informing targeted interventions. Studies were selected based on criteria including a focus on individuals aged up to 25 years old at risk for psychosis, the examination of both risk factors and resilience, and the use of validated instruments for measuring outcomes. Literature searches were conducted across several databases, such as PubMed, Scopus, and Web of Science. Data extraction emphasized odds ratios (ORs) and hazard ratios (HRs) for risk factors, including familial, developmental, and socio-environmental influences. The review included and analyzed nine studies, encompassing a diverse sample of 140,972 participants. Significant findings indicate that highly supportive familial and community environments significantly reduce the risk of psychosis onset. For instance, children with strong family support and engagement in structured activities demonstrated a 40% lower incidence of developing psychotic symptoms [p < 0.05]. Furthermore, the presence of neurobehavioral deficits, such as impaired verbal memory and attention, emerged as significant predictors of psychosis, with these children exhibiting a threefold increase in risk compared to their peers [OR = 3.2, 95% CI: 2.1-4.8, p < 0.01]. Resilience factors play a critical role in mitigating the impact of psychosocial and neurobiological risks in the development of psychosis among youths. Interventions enhancing resilience could potentially alter the trajectory of psychosis development, emphasizing the need for early and targeted psychosocial interventions to support at-risk populations. This study underscores the importance of fostering resilience through both individual-focused and community-based strategies to prevent the onset of psychotic disorders in vulnerable young populations.

Psychological resilience and related influencing factors in patients diagnosed with major depressive disorder in remission: A cross-sectional study

WHAT IS KNOWN ON THE SUBJECT?: Recurrence is common in patients diagnosed with major depressive disorder (MDD). Psychological resilience has been shown to be a protective factor against recurrence of depression. It has important clinical nursing significance to analyse the influencing factors of psychological resilience in major depressive disorder in remission (MDDR) patients. WHAT THE PAPER ADDS TO EXISTING KNOWLEDGE?: There are few previous studies on the influencing factors of psychological resilience in patients diagnosed with MDDR. We found the education levels, personal monthly income, social support, well-being and self-efficacy were influencing factors of psychological resilience in patients diagnosed with MDDR. WHAT ARE THE IMPLICATIONS FOR PRACTICE?: According to the factors affecting the psychological resilience of patients diagnosed with MDDR, targeted clinical nursing is helpful to prevent the recurrence of depression. Nurses should strengthen the nursing of patients with <12 years of education, and patients with personal monthly income less than 5000 RMB. In addition, nurses should cultivate patients' awareness of social support and identity, cultivate their ability to strive for social support, cultivate interpersonal skills and positive emotional experience to improve subjective well-being and carry out self-efficacy training to improve psychological resilience by enhancing patients' internal protective factors.

ABSTRACT

AIM: Psychological resilience is closely related to recurrence of depression. There are few previous studies on the influencing factors of psychological resilience in patients diagnosed with major depressive disorder in remission (MDDR). Here, we investigated the current status of resilience in patients diagnosed with MDDR and its influencing factors.

METHODS

A descriptive cross-sectional study was conducted from June 2019 to April 2021. One hundred and forty-two patients diagnosed with MDDR were recruited from the Department of Psychiatry and Psychology of the General Hospital of Northern Theater Command. Demographic information, social support, well-being, self-efficacy and psychological resilience were collected using self-reported questionnaires.

RESULTS

The psychological resilience of MDDR patients was lower than that of the healthy Chinese adults in China. Multiple logistic regression analysis showed that education, personal monthly income, social support, well-being and self-efficacy were associated with psychological resilience. Receiver operating characteristic (ROC) curve analysis further confirmed that social support, well-being and self-efficacy were associated with psychological resilience.

CONCLUSION

The psychological resilience of MDDR patients was lower than that of the general population in China. The education levels, personal monthly income, social support, well-being and self-efficacy were influencing factors of psychological resilience.

IMPLICATIONS FOR PRACTICE

According to the factors affecting the psychological resilience of patients diagnosed with MDDR, targeted clinical nursing is helpful to prevent the recurrence of depression.

Shared genetic risk factors for depression and stroke

BACKGROUND

The comorbidity of major depressive disorder (MDD) and stroke are common in clinic. There is a growing body of evidence suggesting a bi-directional relationship between stroke and depression. However, the mechanisms underlying the relationship between MDD and stroke are poorly investigated. Considering that both MDD and stroke can be heritable and are influenced by multiple risk genes, shared genetic risk factors between MDD and stroke may exist.

OBJECTIVE

The objective is to review the existing evidence for common genetic risk factors for both MDD and stroke and to outline the possible pathophysiological mechanisms mediating this association.

METHODS

A systematic review and meta-analysis was performed. Gene association studies regarding stroke and depression were searched in the database PubMed, CNKI, and Chinese Biomedical Literature Database before December 2018. Statistical analysis was performed using the software Revman 5.3.

RESULTS

Genetic polymorphisms of 4 genes, methylenetetrahydrofolate reductase (MTHFR) and apolipoprotein E (ApoE) have been demonstrated to associate with the increased risk for both MDD and stroke, while the association between identified polymorphisms in angiotensin converting enzyme (ACE) and serum paraoxonase (PON1) with depression is still under debate, for the existing studies are insufficient in sample size. These results suggest the possible pathophysiological mechanisms that are common to these two disorders, including immune-inflammatory imbalance, increased oxidative and nitrative stress, dysregulation of lipoprotein and lipid metabolism, and changes of cerebrovascular morphology and function. Other associated genes with few or conflicting results have also been included, and a few studies have investigated the effects of the described polymorphisms on MDD and stroke comorbidity, such as post stroke depression.

CONCLUSION

These findings suggest that shared genetic pathways may contribute to the comorbidity of MDD and stroke. Studies to evaluate the shared genetic variations between MDD and stroke may provide insights into the molecular mechanisms that trigger disease progression.

Web-Based Measure of Life Events Using Computerized Life Events and Assessment Record (CLEAR): Preliminary Cross-Sectional Study of Reliability, Validity, and Association With Depression

BACKGROUND

Given the criticisms of life event checklists and the costs associated with interviews, life event research requires a sophisticated but easy-to-use measure for research and clinical practice. Therefore, the Computerized Life Events and Assessment Record (CLEAR), based on the Life Events and Difficulties Schedule (LEDS), was developed.

OBJECTIVE

The objective of our study was to test CLEAR's reliability, validity, and association with depression.

METHODS

CLEAR, the General Health Questionnaire, and the List of Threatening Experiences Questionnaire (LTE-Q) were completed by 328 participants (126 students; 202 matched midlife sample: 127 unaffected controls, 75 recurrent depression cases). Test-retest reliability over 3-4 weeks was examined and validity determined by comparing CLEAR with LEDS and LTE-Q. Both CLEAR and LTE-Q were examined in relation to depression.

RESULTS

CLEAR demonstrated good test-retest reliability for the overall number of life events (0.89) and severe life events (.60). Long-term problems showed similar findings. In terms of validity, CLEAR severe life events had moderate sensitivity (59.1%) and specificity (65.4%) when compared with LEDS. CLEAR demonstrated moderate sensitivity (43.1%) and specificity (78.6%) when compared with LTE-Q. CLEAR severe life events and long-term problems were significantly associated with depression (odds ratio, OR 3.50, 95% CI 2.10 to 5.85, P<.001; OR 3.38, 95% CI 2.02 to 5.67, P<.001, respectively), whereas LTE-Q events were not (OR 1.06, 95% CI 0.43 to 2.60, P=.90).

CONCLUSIONS

CLEAR has acceptable reliability and validity and predicts depression. It, therefore, has great potential for effective use in research and clinical practice identifying stress-related factors for the onset and maintenance of depression and related disorders.

Serotonin transporter gene (5-HTT) rs6354 polymorphism, job-related stress, and their interaction in burnout in healthcare workers in a Chinese hospital

OBJECTIVE

Many studies have reported that long-term exposure to job-related stress can lead to burnout, which may be influenced by genetic and environmental factors. Burnout correlates with depression. This study investigated whether one tag polymorphism rs6354 in 5-HTT gene modulated the influence of job-related stress on burnout in the medical professionals in a Chinese Han population, which to our best knowledge has not been explored.

METHODS

Seven hundred twelve subjects were recruited from a general hospital and measured for burnout symptoms using the Maslach Burnout Inventory (MBI), the stress using the House and Rizzo's Work Stress Scale, and the stressors using the Evers, Frese, and Cooper's Sources of Pressure Scale. The 5-HTT rs6354 polymorphism was genotyped in 376 subjects.

RESULTS

The majority of correlations between the work stress score or the six stressor scores and three burnout subscores were significant (all p < 0.05). There was no significant main effect of the 5-HTT rs6354 genotype on burnout symptoms; however, there was a statistically significant interaction between 5-HTT rs6354 and work stress on burnout (F = 5.08, df = 2, 369, p = 0.007). In the low stress group, G allele carriers had significantly higher burnout level than TT homozygote (F = 11.60, df = 1, 48, p < 0.001). On the contrary, in the high stress group, G allele carriers exhibited significantly lower burnout level compared to TT homozygote (F = 3.86, df = 1, 103, p = 0.025).

CONCLUSIONS

Our findings suggest that the 5-HTT rs6354 polymorphism may modulate the influence of job-related stress on burnout by adjusting serotonin transporter function and neurotransmission, showing that individuals with TT genotype displayed a greater susceptibility to both the detrimental effects of higher stress and the beneficial effects of lower stress compared to those with G allele, which supports the differential-susceptibility hypothesis.

Interactions between the vascular endothelial growth factor gene polymorphism and life events in susceptibility to major depressive disorder in a Chinese population

BACKGROUND

Recent studies suggest that vascular endothelial growth factor (VEGF) is involved in the development of major depressive disorder. The aim of this study is to investigate the interaction between vascular endothelial growth factor (VEGF) polymorphism (+405G/C, rs2010963) and negative life events in the pathogenesis of major depressive disorder (MDD).

METHODS

DNA genotyping was performed on peripheral blood leukocytes in 274 patients with MDD and 273 age-and sex-matched controls. The frequency and severity of negative life events were assessed by the Life Events Scale (LES). A logistics method was employed to assess the gene-environment interaction (G×E).

RESULTS

Differences in rs2010963 genotype distributions were observed between MDD patients and controls. Significant G×E interactions between allelic variation of rs2010963 and negative life events were observed. Individuals carrying the C alleles were susceptible to MDD only when exposed to high-negative life events.

CONCLUSIONS

These results indicate that interactions between the VEGF rs2010963 polymorphism and environment increases the risk of developing MDD.

Polygenic interactions with environmental adversity in the aetiology of major depressive disorder

BACKGROUND

Major depressive disorder (MDD) is a common and disabling condition with well-established heritability and environmental risk factors. Gene-environment interaction studies in MDD have typically investigated candidate genes, though the disorder is known to be highly polygenic. This study aims to test for interaction between polygenic risk and stressful life events (SLEs) or childhood trauma (CT) in the aetiology of MDD.

METHOD

The RADIANT UK sample consists of 1605 MDD cases and 1064 controls with SLE data, and a subset of 240 cases and 272 controls with CT data. Polygenic risk scores (PRS) were constructed using results from a mega-analysis on MDD by the Psychiatric Genomics Consortium. PRS and environmental factors were tested for association with case/control status and for interaction between them.

RESULTS

PRS significantly predicted depression, explaining 1.1% of variance in phenotype (p = 1.9 × 10(-6)). SLEs and CT were also associated with MDD status (p = 2.19 × 10(-4) and p = 5.12 × 10(-20), respectively). No interactions were found between PRS and SLEs. Significant PRSxCT interactions were found (p = 0.002), but showed an inverse association with MDD status, as cases who experienced more severe CT tended to have a lower PRS than other cases or controls. This relationship between PRS and CT was not observed in independent replication samples.

CONCLUSIONS

CT is a strong risk factor for MDD but may have greater effect in individuals with lower genetic liability for the disorder. Including environmental risk along with genetics is important in studying the aetiology of MDD and PRS provide a useful approach to investigating gene-environment interactions in complex traits.

Measuring Life Events and Their Association With Clinical Disorder: A Protocol for Development of an Online Approach

Background

Severe life events are acknowledged as important etiological factors in the development of clinical disorders, including major depression. Interview methods capable of assessing context and meaning of events have demonstrated superior validity compared with checklist questionnaire methods and arguments for interview approaches have resurfaced because choosing the appropriate assessment tool provides clarity of information about gene-environment interactions in depression. Such approaches also have greater potential for understanding and treating clinical cases or for use in interventions.

Objective

(1) To argue that life events need sophisticated measurement not satisfactorily captured in checklist approaches. (2) To review life-events measures and key findings related to disorder, exemplifying depression. (3) To describe an ongoing study with a new online measure and to assess its psychometric properties and the association of life events in relation to disorder and educational outcomes.

Methods

The Computerised Life Events Assessment Record (CLEAR) is under development as a tool for online assessment of adult life events. Based on the Life Events and Difficulties Schedule interview, CLEAR seeks to assess life events to self and close others, link these to other events and difficulties, and utilize calendar-based timing, to improve upon checklist approaches.

Results

The CLEAR study is in the preliminary stages and its results are expected to be made available by the end of 2015.

Conclusions

There is currently no sophisticated technological application of social risk factor assessment, such as life events and difficulties. CLEAR is designed to gather reliable and valid life-event data while combating the limitations of interviews (eg, time consuming and costly) and life-event checklists (eg, inability to accurately measure severity and independence of life events). The advantages of using such innovative methodology for research, clinical practice, and interventions are discussed.

Monoamine-sensitive developmental periods impacting adult emotional and cognitive behaviors

Development passes through sensitive periods, during which plasticity allows for genetic and environmental factors to exert indelible influence on the maturation of the organism. In the context of central nervous system development, such sensitive periods shape the formation of neurocircuits that mediate, regulate, and control behavior. This general mechanism allows for development to be guided by both the genetic blueprint as well as the environmental context. While allowing for adaptation, such sensitive periods are also vulnerability windows during which external and internal factors can confer risk to disorders by derailing otherwise resilient developmental programs. Here we review developmental periods that are sensitive to monoamine signaling and impact adult behaviors of relevance to psychiatry. Specifically, we review (1) a serotonin-sensitive period that impacts sensory system development, (2) a serotonin-sensitive period that impacts cognition, anxiety- and depression-related behaviors, and (3) a dopamine- and serotonin-sensitive period affecting aggression, impulsivity and behavioral response to psychostimulants. We discuss preclinical data to provide mechanistic insight, as well as epidemiological and clinical data to point out translational relevance. The field of translational developmental neuroscience has progressed exponentially providing solid conceptual advances and unprecedented mechanistic insight. With such knowledge at hand and important methodological innovation ongoing, the field is poised for breakthroughs elucidating the developmental origins of neuropsychiatric disorders, and thus understanding pathophysiology. Such knowledge of sensitive periods that determine the developmental trajectory of complex behaviors is a necessary step towards improving prevention and treatment approaches for neuropsychiatric disorders.

Major depressive disorder in DSM-5: implications for clinical practice and research of changes from DSM-IV

The changes in diagnostic criteria for major depressive disorder (MDD) from the fourth to the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM) may appear small but have important consequences for how the diagnosis is used. In DSM-5, MDD is part of the new "Depressive disorders" section, which is separate from "Bipolar disorders", marking a division in what had been known as "Mood disorders". A small wording change has expanded the core mood criterion to include hopelessness, potentially broadening the diagnosis. The replacement of an operationalized bereavement exclusion with a call for clinical judgment in distinguishing normal reactions to significant loss from a disorder in need of clinical attention makes the diagnosis less objective and complicates investigations of the relationship between adversity and depression. A new persistent depressive disorder category is intended to encompass both dysthymia and chronic depression, but its relationship to MDD is ambiguous with conflicting statements on whether the two diagnoses should be concurrent if both sets of criteria are fulfilled. Clarification is also needed on whether MDD can be concurrent with the new broad "other specified bipolar and related disorders". New specifiers of MDD "with anxious distress" and "with mixed features" allow characterization of additional symptoms. The specifier "with perinatal onset" expands on the DSM-IV "postnatal onset" to include onset during pregnancy. We review the changes in MDD definition, provide guidance on their implementation and discuss their implications for clinical practice and research.

The dynamic nature of depression: a new micro-level perspective of mental disorder that meets current challenges

The examination of moment-to-moment, 'micro-level' patterns of experience and behaviour using experience sampling methodology has contributed to our understanding of the 'macro-level' development of full-blown symptoms and disorders. This paper argues that the micro-level perspective can be used to identify the smallest building blocks underlying the onset and course of mental ill-health. Psychopathology may be the result of the continuous dynamic interplay between micro-level moment-to-moment experiences and behavioural patterns over time. Reinforcing loops between momentary states may alter the course of mental health towards either a more or less healthy state. An example with observed data, from a population of individuals with depressive symptoms, supports the validity of a dynamic network model of psychopathology and shows that together and over time, this continuous interplay between momentary states may result in the cluster of symptoms we call major depressive disorder. This approach may help conceptualize the nature of mental disorders, and generate individualized insights useful for diagnosis and treatment in psychiatry.

Functional polymorphism in the brain-derived neurotrophic factor gene interacts with stressful life events but not childhood maltreatment in the etiology of depression

BACKGROUND

We test the hypothesis that the functional Val66Met polymorphism of BDNF interacts with recent life events to produce onset of new depressive episodes. We also explore the possibility that the Met allele of this polymorphism interacts with childhood maltreatment to increase the risk of chronic depression.

METHODS

In a risk-enriched combined sample of unrelated women, childhood maltreatment and current life events were measured with the Childhood Experience of Care and Abuse, and Life Events and Difficulties Schedule interviews. Chronic episodes of depression (12 months or longer) during adulthood and onset of a major depressive episode during a 12-month follow-up were established with the Schedules for Clinical Assessment in Neuropsychiatry interview.

RESULTS

Met alleles of BDNF moderated the relationship between recent life events and adult onsets of depression in a significant gene-environment interaction (interaction risk difference 0.216, 95% CI 0.090-0.342; P =.0008). BDNF did not significantly influence the effect of childhood maltreatment on chronic depression in the present sample.

CONCLUSIONS

The Met allele of BDNF increases the risk of a new depressive episode following a severe life event. The BDNF and the serotonin transporter gene length polymorphism (5-HTTLPR) and BDNF may contribute to depression through distinct mechanisms involving interactions with childhood and adulthood adversity respectively, which may, in combination, be responsible for a substantial proportion of depression burden in the general population.

Gene-environment interactions in common mental disorders: an update and strategy for a genome-wide search

A decade of research has demonstrated the explanatory potential of interplay between genetic variants and environmental factors in the development of common mental disorders. Initial findings have undergone tests of replicability and specificity. Some gene-environment interactions have been confirmed, some have not replicated and yet other turned out to be more specific than initially thought. Specific and complementary roles of genetic factors have been delineated: a common functional length polymorphism in the serotonin transporter gene (5-HTTLPR) moderated the effect of childhood maltreatment on chronic depression in adulthood, but did not substantially influence the effects of adult stressful life events on the onset of new depressive episodes; in contrast, a common functional polymorphism in the brain-derived neurotrophic factor gene (BDNF) moderated the effect of stressful life events in adulthood in triggering new depressive episodes, but did not influence the effects of childhood maltreatment. Molecular mechanisms underlying gene-environment interactions are being uncovered, including DNA methylation and other epigenetic modifications. New gene-environment interactions continue to be reported, still largely from hypothesis-driven research. Statistical and biological prioritization strategies are proposed to facilitate a systematic discovery of novel gene-environment interactions in genome-wide analyses.

Genome-wide association analysis accounting for environmental factors through propensity-score matching: application to stressful live events in major depressive disorder

Stressful life events are an established trigger for depression and may contribute to the heterogeneity within genome-wide association analyses. With depression cases showing an excess of exposure to stressful events compared to controls, there is difficulty in distinguishing between "true" cases and a "normal" response to a stressful environment. This potential contamination of cases, and that from genetically at risk controls that have not yet experienced environmental triggers for onset, may reduce the power of studies to detect causal variants. In the RADIANT sample of 3,690 European individuals, we used propensity score matching to pair cases and controls on exposure to stressful life events. In 805 case-control pairs matched on stressful life event, we tested the influence of 457,670 common genetic variants on the propensity to depression under comparable level of adversity with a sign test. While this analysis produced no significant findings after genome-wide correction for multiple testing, we outline a novel methodology and perspective for providing environmental context in genetic studies. We recommend contextualizing depression by incorporating environmental exposure into genome-wide analyses as a complementary approach to testing gene-environment interactions. Possible explanations for negative findings include a lack of statistical power due to small sample size and conditional effects, resulting from the low rate of adequate matching. Our findings underscore the importance of collecting information on environmental risk factors in studies of depression and other complex phenotypes, so that sufficient sample sizes are available to investigate their effect in genome-wide association analysis.

Research review: the role of cytokines in depression in adolescents: a systematic review

BACKGROUND

While cytokines have been implicated in the pathophysiology of depression in adults, the potential role in younger age groups such as adolescents is less clear. This article therefore reviews the literature (a) to explore the relationship between cytokines and depression in adolescents, and (b) to examine how cytokines may be related to adolescent depression in the context of other neurobiological theories of depression.

METHOD

A systematic review of the scientific literature on the subject was conducted in February 2013, searching the Web of Knowledge, PubMed (Medline), PsycInfo and Cochrane electronic databases.

RESULTS

Eighteen studies were identified measuring both depression or depressive symptoms and cytokines or immune markers in adolescents. Adolescents with depression show age-specific characteristics of the immune and inflammatory system, specifically in NK cell activity and in pro-inflammatory cytokines (such as IL-1β and TNF-α). In addition, the role of cytokines in adolescent depression is influenced by neurodevelopment, hormonal changes, stress and trauma.

CONCLUSIONS

There may be differences in the neurobiology of adolescent major depressive disorder (MDD) compared with adult MDD. Increased understanding of the role of cytokines in adolescent MDD may lead to improved outcomes in the treatment of adolescent depression.

The interaction between child maltreatment, adult stressful life events and the 5-HTTLPR in major depression

Both childhood maltreatment and adult stressful life events are established risk factors for the onset of depression in adulthood. However, the interaction between them can be viewed through two conflicting frameworks. Under a mismatch hypothesis stressful childhoods allow 'adaptive programming' for a stressful adulthood and so can be protective. Only when childhood and adulthood do not match is there a risk of behavioural problems. Alternatively, under the cumulative stress hypothesis we expect increased risk with each additional stressor. It has also been suggested that an individual's genetic background may determine the extent they undergo adaptive programming, and so which of these two hypotheses is relevant. In this study we test for an interaction between exposure to childhood maltreatment and adult stressful life events in a retrospective sample of 455 individuals, using major depression as the outcome. We also test whether this interaction differs by genotype at the 5-HTTLPR, a candidate for an individual's plasticity to adaptive programming. Early maltreatment and stressful life events in adulthood interacted to produce increased risk for depression over each individually (p = 0.055). This supports the cumulative stress hypothesis over the mismatch hypothesis, at least with respect to severe environmental risk factors. This effect was not altered by 5-HTTLPR allele, suggesting there was no difference by genotype in adaptive programming to these events. We suggest that the apparent additional vulnerability to stressful events of those who have experienced maltreatment has clinical relevance, highlighting the importance of providing support beyond the immediate aftermath of maltreatment into adulthood.

The current state of play on the molecular genetics of depression

BACKGROUND

It has been well established that both genes and non-shared environment contribute substantially to the underlying aetiology of major depressive disorder (MDD). A comprehensive overview of genetic research in MDD is presented. Method Papers were retrieved from PubMed up to December 2011, using many keywords including: depression, major depressive disorder, genetics, rare variants, gene-environment, whole genome, epigenetics, and specific candidate genes and variants. These were combined in a variety of permutations.

RESULTS

Linkage studies have yielded some promising chromosomal regions in MDD. However, there is a continued lack of consistency in association studies, in both candidate gene and genome-wide association studies (GWAS). Numerous factors may account for variable results including the use of different diagnostic approaches, small samples in early studies, population stratification, epigenetic phenomena, copy number variation (CNV), rare variation, and phenotypic and allelic heterogeneity. The conflicting results are also probably, in part, a consequence of environmental factors not being considered or controlled for.

CONCLUSIONS

Each research group has to identify what issues their sample may best address. We suggest that, where possible, more emphasis should be placed on the environment in molecular behavioural genetics to identify individuals at environmental high risk in addition to genetic high risk. Sequencing should be used to identify rare and alternative variation that may act as a risk factor, and a systems biology approach including gene-gene interactions and pathway analyses would be advantageous. GWAS may require even larger samples with reliably defined (sub)phenotypes.

Interaction between specific forms of childhood maltreatment and the serotonin transporter gene (5-HTT) in recurrent depressive disorder

BACKGROUND

There is inconsistent evidence of interaction between stressful events and a serotonin transporter promoter polymorphism (5-HTTLPR) in depression. Recent studies have indicated that the moderating effect of 5-HTTLPR may be strongest when adverse experiences have occurred in childhood and the depressive symptoms persist over time. However, it is unknown whether this gene-environment interaction is present for recurrent depressive disorder and different forms of maltreatment. Therefore, patients with recurrent clinically diagnosed depression and controls screened for the absence of depression were utilised to examine the moderating effect of 5-HTTLPR on associations between specific forms of childhood adversity and recurrent depression.

METHOD

A sample of 227 recurrent unipolar depression cases and 228 never psychiatrically ill controls completed the Childhood Trauma Questionnaire to assess exposure to sexual, physical and emotional abuse, physical and emotional neglect in childhood. DNA extracted from blood or cheek swabs was genotyped for the short (s) and long (l) alleles of 5-HTTLPR.

RESULTS

All forms of childhood maltreatment were reported as more severe by cases than controls. There was no direct association between 5-HTTLPR and depression. Significant interactions with additive and recessive 5-HTTLPR genetic models were found for overall severity of maltreatment, sexual abuse and to a lesser degree for physical neglect, but not other maltreatment types.

LIMITATIONS

The cross-sectional design limits causal inference. Retrospective report of childhood adversity may have reduced the accuracy of the findings.

CONCLUSIONS

This study provides support for the role of interplay between 5-HTTLPR and a specific early environmental risk in recurrent depressive disorder.

5-HTTLPR and early childhood adversities moderate cognitive and emotional processing in adolescence

BACKGROUND

Polymorphisms in the promoter region of the serotonin transporter gene (5-HTTLPR) and exposure to early childhood adversities (CA) are independently associated with individual differences in cognitive and emotional processing. Whether these two factors interact to influence cognitive and emotional processing is not known.

METHODOLOGY AND PRINCIPAL FINDINGS

We used a sample of 238 adolescents from a community study characterised by the presence of the short allele of 5-HTTLPR (LL, LS, SS) and the presence or absence of exposure to CA before 6 years of age. We measured cognitive and emotional processing using a set of neuropsychological tasks selected predominantly from the CANTAB® battery. We found that adolescents homozygous for the short allele (SS) of 5-HTTLPR and exposed to CA were worse at classifying negative and neutral stimuli and made more errors in response to ambiguous negative feedback. In addition, cognitive and emotional processing deficits were associated with diagnoses of anxiety and/or depressions.

CONCLUSION AND SIGNIFICANCE

Cognitive and emotional processing deficits may act as a transdiagnostic intermediate marker for anxiety and depressive disorders in genetically susceptible individuals exposed to CA.