5-HTTLPR X Stress in Adolescent Depression: Moderation by MAOA and Gender

Role of polygenic risk scores in the association between chronotype and health risk behaviors

BACKGROUND

This study explores the association between chronotypes and adolescent health risk behaviors (HRBs) by testing how genetic background moderates these associations and clarifies the influence of chronotypes and polygenic risk score (PRS) on adolescent HRBs.

METHODS

Using VOS-viewer software to select the corresponding data, this study used knowledge domain mapping to identify and develop the research direction with respect to adolescent risk factor type. Next, DNA samples from 264 students were collected for low-depth whole-genome sequencing. The sequencing detected HRB risk loci, 49 single nucleotide polymorphisms based to significant SNP. Subsequently, PRSs were assessed and divided into low, moderate, and high genetic risk according to the tertiles and chronotypes and interaction models were constructed to evaluate the association of interaction effect and clustering of adolescent HRBs. The chronotypes and the association between CLOCK-PRS and HRBs were examined to explore the association between chronotypes and mental health and circadian CLOCK-PRS and HRBs.

RESULTS

Four prominent areas were displayed by clustering information fields in network and density visualization modes in VOS-viewer. The total score of evening chronotypes correlated with high-level clustering of HRBs in adolescents, co-occurrence, and mental health, and the difference was statistically significant. After controlling covariates, the results remained consistent. Three-way interactions between chronotype, age, and mental health were observed, and the differences were statistically significant. CLOCK-PRS was constructed to identify genetic susceptibility to the clustering of HRBs. The interaction of evening chronotypes and high genetic risk CLOCK-PRS was positively correlated with high-level clustering of HRBs and HRB co-occurrence in adolescents, and the difference was statistically significant. The interaction between the sub-dimensions of evening chronotypes and the high genetic CLOCK-PRS risk correlated with the outcome of the clustering of HRBs and HRB co-occurrence.

CONCLUSIONS

The interaction of PRS and chronotype and the HRBs in adolescents appear to have an association, and the three-way interaction between the CLOCK-PRS, chronotype, and mental health plays important roles for HRBs in adolescents.

Health Disparities by Sexual Orientation: Implications of Genetic and Environmental Explanations

Xu and colleagues add to the growing research literature on the role of potential familial (i.e., genetic and shared environment) causes in sexual orientation and in the relation between sexual orientation and poor mental health, in which lesbian, gay, bisexual, and other sexual minority individuals have poorer mental health than heterosexual individuals. I address several implications of the findings by Xu et al. and others. First, the nuance or complexity of genetics is considered, given the implications of genetics for health via a single gene, epistasis, or epigenetics. Second, I highlight the magnitude of the genetic relation between sexual orientation and psychopathology, suggesting some, but not all, sexual minority individuals may differ from heterosexual individuals on psychiatric vulnerability. In turn, this suggests that research should identify for whom or under what circumstances the relation holds. Third, I underscore the need for a within-subjects design, in which attention turns to differences among sexual minority individuals. Fourth, the need to reevaluate Minority Stress Theory, the predominant theory accounting for health disparities by sexual orientation, is addressed because of the implications of genetics for health. Fifth, I acknowledge the concern attached to genetic research for potentially compounding the stigmatization already experienced by sexual minority individuals. Nevertheless, this research is occurring and will likely increase in volume. It will inform understanding of sexual minority individuals.

Biomarkers in Child and Adolescent Depression

Despite the significant prevalence of Major Depressive Disorder in the pediatric population, the pathophysiology of this condition remains unclear, and the treatment outcomes poor. Investigating tools that might aid in diagnosing and treating early-onset depression seems essential in improving the prognosis of the future disease course. Recent studies have focused on searching for biomarkers that constitute biochemical indicators of MDD susceptibility, diagnosis, or treatment outcome. In comparison to increasing evidence of possible biomarkers in adult depression, the studies investigating this subject in the youth population are lacking. This narrative review aims to summarize research on molecular and biochemical biomarkers in child and adolescent depression in order to advocate future directions in the research on this subject. More studies on depression involving the youth population seem vital to comprehend the natural course of the disease and identify features that may underlie commonly observed differences in treatment outcomes between adults and children.

Intersection of Sex and Depression: Pathogenesis, Presentation, and Treatments

Major Depressive Disorder (MDD) is a highly prevalent, debilitating disorder. According to the World Health Organization, approximately 5% of adults suffer from depression worldwide and more women than men are affected. Yet, we have a very limited understanding of the pathogenesis of the disease, how sex and genetics influence the pathophenotype of MDD, and how they contribute to the responses to pharmacological treatment. This chapter addresses key theories about the etiology of depression, the variations in epidemiology and presentation, and the treatment options with respect to sex and gender. Additionally, we discuss the emerging wave of treatment modalities, diagnosis, and research focusing on MDD.

Gender differences in the association of polygenic risk and divergent depression trajectories from mid to late life: a national longitudinal study

Our research fills a critical gap in the depression literature by utilizing a life course perspective to examine gender-gene interactions in association with depression trajectories over time. Using data from the Health and Retirement Study, we estimated multi-level negative binomial and logistic mixed models to analyze gender-specific trajectories of depressive symptoms (CESD-8) and potential clinical depression risk from middle to late adulthood in relation to gender-by-polygenic-risk (PRS) interactions. We found increasingly greater female-male gaps in the CESD-8 scale and a higher probability of clinical depression risk with increasing polygenic risk scores. Furthermore, females' higher genetic vulnerabilities to depressive conditions than males vary from ages 51 to 90 years, with most salient larger differences at oldest old ages at 76-85 (e.g. 0.28 higher CESD-8 scale for females at ages 76-85 years than for similar-aged males; higher 3.44% probability of depression risk for females at ages 81-85 compared to similar-aged males) followed by old ages at 61-70  years (e.g. about 2.40% higher probability of depression risk for females at ages 61-70 years than for similar-aged males) in comparison to younger ages during middle adulthood. This study contributes to new knowledge of how gender-by-polygenic-risk interactions are associated with depression trajectories across the life course.

The Role of Sex in Genetic Association Studies of Depression

Depression is the most common mental illness in the U.S. affecting nearly 40 million adults age 18 years and older. Depression has both genetic and environmental influences. In addition, women are more likely to be affected by depression than men. However, the relationship between genes and depression is complex and may be influenced by sex. Understanding the genetic basis of sex-specific differences for depression has the potential to lead to new biological understanding of the etiology of depression in females compared to males and to promote the development of novel and more effective pharmacotherapies. This review examines the role of sex in genetic associations with depression for both genome-wide association and candidate gene studies. While the genetic association signals of depression differ by sex, the role of sex in the heritability of depression is complex and warrants further investigation.

Gender Differences in Depression: Evidence From Genetics

Compared with men, female accounts for a larger proportion of patients with depression. Behavioral genetics researches find gender differences in genetic underpinnings of depression. We found that gender differences exist in heritability and the gene associated with depression after reviewing relevant research. Both genes and gene-environment interactions contribute to the risk of depression in a gender-specific manner. We detailed the relationships between serotonin transporter gene-linked promoter region (5-HTTLPR) and depression. However, the results of these studies are very different. We explored the reasons for the contradictory conclusions and provided some suggestions for future research on the gender differences in genetic underpinnings of depression.

The MAOA Gene Influences the Neural Response to Psychosocial Stress in the Human Brain

The stress response is regulated by many mechanisms. Monoamine oxidase A (MAOA) has been related to many mental illnesses. However, few studies have explored the relationship between MAOA and acute laboratory-induced psychosocial stress with functional magnetic resonance imaging (fMRI). In the current study, the Montreal Imaging Stress Task (MIST) and fMRI were used to investigate how MAOA influences the stress response. Increased cortisol concentrations were observed after the task; functional connectivity between the bilateral anterior hippocampus and other brain regions was reduced during stress. MAOA-H allele carriers showed greater deactivation of the right anterior hippocampus and greater cortisol response after stress than did MAOH-L allele carriers. Hippocampal deactivation may lead to disinhibition of the hypothalamic-pituitary-adrenal (HPA) axis and the initiation of stress hormone release under stress. Our results suggest that the MAOA gene regulates the stress response by influencing the right anterior hippocampus.

Serotonergic influence on depressive symptoms and trait anxiety is mediated by negative life events and frontal activation in children and adolescents

Depression and anxiety are common in childhood and adolescence. Even though cardinal symptoms differ, there is a considerable overlap regarding the pathogenic influence of serotonergic innervation, negative life experience, disturbed emotion perception/affect regulation, and impaired neural functioning in the fronto-limbic circuit. In this study, we examined the effect of the 5-HTTLPR/rs25531 genotype on depressive symptoms and trait anxiety under the consideration of the amount of negative life events in healthy children and adolescents (N = 389). In a subsample of 49 subjects, we performed fMRI to add fronto-limbic brain activation as a second interacting factor. Across all subjects, negative life events moderated the influence of the 5-HTTLPR/rs25531 genotype on both depressive symptoms and trait anxiety. In the fMRI subsample, 5-HTTLPR/rs25531 S + S/L_G + S/L_A + L_GL_A + L_GL_G genotype-associated left middle frontal gyrus (MFG) activation mediated the influence of 5-HTTLPR/rs25531 genotype on depressive symptoms, however, only in combination with negative life events. Genetic influence on trait anxiety was predominantly mediated by negative life events; only L_AL_A genotype-specific activation in the right MFG worked as a mediator in combination with negative life events. The present findings hint towards distinct mechanisms mediating the influence of 5-HTTLPR/rs25531 genotype on depressive symptoms and anxiety, with negative life events playing a crucial role in both phenotypes. With regard to depressive symptoms, however, this influence was only visible in combination with MFG activation, whereas, in anxiety, it was independent of brain activation.

Brain monoamine oxidase A in seasonal affective disorder and treatment with bright light therapy

Increased cerebral monoamine oxidase A (MAO-A) levels have been shown in non-seasonal depression using positron emission tomography (PET). Seasonal affective disorder (SAD) is a sub-form of major depressive disorder and is typically treated with bright light therapy (BLT). The serotonergic system is affected by season and light. Hence, this study aims to assess the relevance of brain MAO-A levels to the pathophysiology and treatment of SAD. Changes to cerebral MAO-A distribution (1) in SAD in comparison to healthy controls (HC), (2) after treatment with BLT and (3) between the seasons, were investigated in 24 patients with SAD and 27 HC using [¹¹C]harmine PET. PET scans were performed in fall/winter before and after 3 weeks of placebo-controlled BLT, as well as in spring/summer. Cerebral MAO-A distribution volume (V_T, an index of MAO-A density) did not differ between patients and HC at any of the three time-points. However, MAO-A V_T decreased from fall/winter to spring/summer in the HC group (F_{1, 187.84} = 4.79, p < 0.050), while SAD showed no change. In addition, BLT, but not placebo, resulted in a significant reduction in MAO-A V_T (F_{1, 208.92} = 25.96, p < 0.001). This is the first study to demonstrate an influence of BLT on human cerebral MAO-A levels in vivo. Furthermore, we show that SAD may lack seasonal dynamics in brain MAO-A levels. The lack of a cross-sectional difference between patients and HC, in contrast to studies in non-seasonal depression, may be due to the milder symptoms typically shown by patients with SAD.

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.

Sex differences modulating serotonergic polymorphisms implicated in the mechanistic pathways of risk for depression and related disorders

Despite consistent observations of sex differences in depression and related emotional disorders, we do not yet know how these sex differences modulate the effects of genetic polymorphisms implicated in risk for these disorders. This Mini-Review focuses on genetic polymorphisms of the serotonergic system to illustrate how sex differences might modulate the neurobiological pathways involved in the development of depression. We consider the interacting role of environmental factors such as early-life stress. Given limited current knowledge about this topic, we highlight methodological considerations, challenges, and guidelines for future research. © 2016 Wiley Periodicals, Inc.

Association between childhood health, socioeconomic and school-related factors and effort-reward imbalance at work: a 25-year follow-up study

OBJECTIVES

Stress pathways can have origins in childhood, but few early predictors have been explored in relation to adult job stress. This study examined whether childhood school, health or socioeconomic factors were associated with adult job stress.

METHODS

Data came from the Childhood Determinants of Adult Health study that began in 1985 with children aged 7-15 years who reported effortreward imbalance (ERI) scales at ages 31-41 years. Linear regression assessed the association between childhood factors and adult ERI adjusted for age and socioeconomic position (SEP) in childhood and adulthood.

RESULTS

There were between 999 and 1390 participants in each analysis. Lower adulthood ERI, indicating less job stress, was predicted by several school-related factors in men. For example, each higher category of learner self-concept was associated with a 19% (95% CI - 32% to 6%) reduction in adult ERI, and each unit increase in academic attainment was associated with a 15% (95% CI -28% to 3%) reduction in adult ERI. Childhood health was associated with adult ERI. For example, in women, overweight children had 14% (95% CI 5% to 22%) higher adult ERI scores compared with healthy weight children, and each unit of negative affect was associated with 2% (95% CI 1% to 4%) increase in adult ERI. Adult SEP had no effect on these associations for men but explained some of the effect in women. Childhood SEP had inconsistent associations with adult ERI.

CONCLUSION

Our findings suggest that a range of childhood socioeconomic, school- and health-related factors might contribute to the development of job stress in adulthood.

MAOA Influences the Trajectory of Attentional Development

Attention is vital to success in all aspects of life (Meck and Benson, 2002; Erickson et al., 2015), hence it is important to identify biomarkers of later attentional problems early enough to intervene. Our objective was to determine if any of 11 genes (APOE, BDNF, HTR4, CHRNA4, COMT, DRD4, IGF2, MAOA, SLC5A7, SLC6A3, and SNAP25) predicted the trajectory of attentional development within the same group of children between infancy and childhood. We recruited follow up participants from children who participated as infants in visual attention studies and used a similar task at both time points. Using multilevel modeling, we associated changes in the participant’s position in the distribution of scores in infancy to his/her position in childhood with genetic markers on each of 11 genes. While all 11 genes predicted reaction time (RT) residual scores, only Monoamine oxidase A (MAOA) had a significant interaction including time point. We conclude that the MAOA single nucleotide polymorphism (SNP) rs1137070 is useful in predicting which girls are likely to develop slower RTs on an attention task between infancy and childhood. This early identification is likely to be helpful in early intervention.

5-HTTLPR and gender differences in affective disorders: A systematic review

BACKGROUND

Serotonin transporter-linked polymorphic region (5-HTTLPR) variants have been extensively studied in psychiatric disorders. Although gender effects have been reported, they have not been comprehensively reviewed. The aim of our study was to summarize literature findings on 5-HTTLPR and gender differences in affective disorders.

METHODS

A systematic search of PubMed, ISI Web of Knowledge, and PsycINFO databases was performed for dates until January 2015. The included articles (n=78) analyzed the association between 5-HTTLPR and affective spectrum disorders, taking into account gender. The quality of each study was assessed through STROBE and CONSORT.

RESULTS

5-HTTLPR modulation of affective disorders varied by gender. The S allele (or SS genotype) seemed to be differently associated with an increased risk of depression, depressive symptoms, anxiety traits and symptoms, and symptoms of internalizing behavior among women and an increased risk of aggressiveness, conduct disorder and symptom counts of externalizing behavior among men. Moreover, the presence of stressful life events reinforced the association. Interestingly, these differences seemed to begin with adolescence and were not consistent among the elderly, suggesting a plausible role of hormonal fluctuations.

LIMITATIONS

The review is limited by the small number of included papers, due to the paucity of information in the literature regarding 5-HTTLPR and gender.

CONCLUSIONS

5-HTTLPR variants may exert a differential modulation on a number of features depending on gender. Further studies are needed to more deeply investigate the effect of 5-HTTLPR×gender on the modulation of affective disorders.

The Involvement of Genes in Adolescent Depression: A Systematic Review

Numerous studies have reported on the roles of genetic factors in the development of depression in adolescents and young adults. However, there are few systematic reviews that update our understanding of adolescent depression with the biological findings identifying the roles of gene expression and/or polymorphism(s). This review systematically summarized the findings that clearly identified the contribution of a gene to the risk of depression in adolescents between the ages of 10 and 19 years old and young adults between the ages of 20 and 25 years old. Data were obtained through searching PubMed, Embase, and Web of Science. A total of 47 studies on early adolescence and three studies on young adults were included in the current review. Most articles studied genes in the serotonergic system (n = 26), dopaminergic system (n = 3), and the Brain-derived neurotropic factor (BDNF) gene (n = 12). 92.3% of studies (24/26) identified positive associations of 5-HTTLPR polymorphism with depressive illness or depressive symptoms. 83.3% of studies (10/12) found positive association between BDNF Val66Met genotype and adolescent depressive symptoms. More studies should be conducted on the 18 genes reported in a few studies to clarify their roles in the risk for adolescent depression.

Depression from childhood into late adolescence: Influence of gender, development, genetic susceptibility, and peer stress

Depression is a debilitating mental illness with clear developmental patterns from childhood through late adolescence. Here, we present data from the Gene Environment Mood (GEM) study, which used an accelerated longitudinal cohort design with youth (N = 665) starting in 3rd, 6th, and 9th grades, and a caretaker, who were recruited from the general community, and were then assessed repeatedly through semistructured diagnostic interviews every 6 months over 3 years (7 waves of data) to establish and then predict trajectories of depression from age 8 to 18. First, we demonstrated that overall prevalence rates of depression over time, by age, gender, and pubertal status, in the GEM study closely match those trajectories previously obtained in past developmental epidemiological research. Second, we tested whether a genetic vulnerability-stress model involving 5-HTTLPR and chronic peer stress was moderated by developmental factors. Results showed that older aged adolescents with SS/SL genotype, who experienced higher peer chronic stress over 3 years, were the most likely to be diagnosed with a depressive episode over time. Girls experiencing greater peer chronic stress were the most likely to develop depression. This study used repeated assessments of diagnostic interviewing in a moderately large sample of youth over 3 years to show that depression rates increase in middle to late adolescence, or postpubertally, and that the gender difference in depression emerges earlier in adolescence (age 12.5), or postpubertally. Additionally, genetically susceptible older adolescents who experience chronic peer stress were the most likely to become depressed over time.

Serotonin transporter gene polymorphism (5-HTTLPR) L allele interacts with stress to increase anxiety symptoms in Chinese adolescents: a multiwave longitudinal study

BACKGROUND

Previous studies of the interaction between a functional polymorphism in the serotonin transporter gene-linked promoter region (5-HTTLPR) and stress in anxiety-related phenotypes have produced inconsistent results. The aim of the current study was to examine the effect of the 5-HTTLPR × stress interaction on anxiety symptoms in Chinese adolescents.

METHODS

A total of 651 healthy adolescents [323 females and 328 males; age 14-17 (mean = 16.27, standard deviation = 0.77)] participated in this study. At the initial assessment, participants completed self-report measures assessing anxiety symptoms, depressive symptoms and stressful life events. Additionally, anxiety symptoms and stressful life events were assessed once every 3 months for the subsequent 9 months. A hierarchical linear model (HLM) was used to investigate the 5-HTTLPR × stress interaction.

RESULTS

The HLM indicated no main effect of 5-HTTLPR on anxiety symptoms. Significant 5-HTTLPR × stress interaction effect in predicting anxiety symptoms was found. Specifically, individuals with the 5-HTTLPR L allele exhibited more anxiety symptoms related to stressful life events.

CONCLUSIONS

The association between stress and anxiety symptoms is moderated by 5-HTTLPR. The 5-HTTLPR L allele increases individuals' vulnerability to anxiety under stress situations.

Polygenic risk, stressful life events and depressive symptoms in older adults: a polygenic score analysis

BACKGROUND

Previous studies suggest that the relationship between genetic risk and depression may be moderated by stressful life events (SLEs). The goal of this study was to assess whether SLEs moderate the association between polygenic risk of major depressive disorder (MDD) and depressive symptoms in older adults.

METHOD

We used logistic and negative binomial regressions to assess the associations between polygenic risk, SLEs and depressive symptoms in a sample of 8761 participants from the Health and Retirement Study. Polygenic scores were derived from the Psychiatric Genomics Consortium genome-wide association study of MDD. SLEs were operationalized as a dichotomous variable indicating whether participants had experienced at least one stressful event during the previous 2 years. Depressive symptoms were measured using an eight-item Center for Epidemiologic Studies Depression Scale subscale and operationalized as both a dichotomous and a count variable.

RESULTS

The odds of reporting four or more depressive symptoms were over twice as high among individuals who experienced at least one SLE (odds ratio 2.19, 95% confidence interval 1.86-2.58). Polygenic scores were significantly associated with depressive symptoms (β = 0.21, p ⩽ 0.0001), although the variance explained was modest (pseudo r 2 = 0.0095). None of the interaction terms for polygenic scores and SLEs was statistically significant.

CONCLUSIONS

Polygenic risk and SLEs are robust, independent predictors of depressive symptoms in older adults. Consistent with an additive model, we found no evidence that SLEs moderated the association between common variant polygenic risk and depressive symptoms.

Association study of monoamine oxidase-A gene promoter polymorphism (MAOA-uVNTR) with self-reported anxiety and other psychopathological symptoms in a community sample of early adolescents

The polymorphism upstream of the gene for monoamine oxidase A (MAOA-uVNTR) is reported to be an important enzyme involved in human physiology and behavior. With a sample of 228 early-adolescents from a community sample (143 girls) and adjusting for environmental variables, we examined the influence of MAOA-uVNTR alleles on the scores obtained in the Screen for Childhood Anxiety and Related Emotional Disorders and in the Child Symptom Inventory-4. Our results showed that girls with the high-activity MAOA allele had higher scores for generalized and total anxiety than their low-activity peers, whereas boys with the low-activity allele had higher social phobia scores than boys with the high-activity allele. Results for conduct disorder symptoms did not show a significant relationship between the MAOA alleles and the presence of these symptoms. Our findings support a possible association, depending on gender, between the MAOA-uVNTR polymorphism and psychopathological disorders such as anxiety, which affects high rates of children and adolescents.

5-HTTLPR, Suicidal Behavior by Others, Depression, and Criminal Behavior During Adolescence

Vicarious strains like suicidal behavior on the part of others have been shown to be predictive of both negative emotions and antisocial behavior during adolescence. Little research to date, however, has examined the role that biological factors play in moderating these relationships. Using a sample of adolescents drawn from the National Longitudinal Survey of Adolescent Health ( N = 7,995), and drawing on two separate, but related, theories, I explore whether the serotonin transporter gene (5-HTTLPR) interacts with suicidal behavior by others to affect depression and self-reported crime. Results of ordinary least squares and negative binomial regressions reveal that suicide by others interacts with 5-HTTLPR to increase both depression and crime for males but not females, net of controls. Thus, 5-HTTLPR may be implicated in shaping negative emotions and antisocial behavior among males during adolescence by moderating the effects of suicide by others. Implications for theory are discussed.

The role of the monoamine oxidase A gene in moderating the response to adversity and associated antisocial behavior: a review

Hereditary factors are increasingly attracting the interest of behavioral scientists and practitioners. Our aim in the present article is to introduce some state-of-the-art topics in behavioral genetics, as well as selected findings in the field, in order to illustrate how genetic makeup can modulate the impact of environmental factors. We focus on the most-studied polymorphism to date for antisocial responses to adversity: the monoamine oxidase A gene. Advances, caveats, and promises of current research are reviewed. We also discuss implications for the use of genetic information in applied settings.

Monoamine polygenic liability in health and cocaine dependence: imaging genetics study of aversive processing and associations with depression symptomatology

BACKGROUND

Gene polymorphisms that affect serotonin signaling modulate reactivity to salient stimuli and risk for emotional disturbances. Here, we hypothesized that these serotonin genes, which have been primarily explored in depressive disorders, could also have important implications for drug addiction, with the potential to reveal important insights into drug symptomatology, severity, and/or possible sequelae such as dysphoria.

METHODS

Using an imaging genetics approach, the current study tested in 62 cocaine abusers and 57 healthy controls the separate and combined effects of variations in the serotonin transporter (5-HTTLPR) and monoamine oxidase A (MAOA) genes on processing of aversive information. Reactivity to standardized unpleasant images was indexed by a psychophysiological marker of stimulus salience (i.e., the late positive potential (LPP) component of the event-related potential) during passive picture viewing. Depressive symptomatology was assessed with the Beck Depression Inventory (BDI).

RESULTS

Results showed that, independent of diagnosis, the highest unpleasant LPPs emerged in individuals with MAOA-Low and at least one 'Short' allele of 5-HTTLPR. Uniquely in the cocaine participants with these two risk variants, higher unpleasant LPPs correlated with higher BDI scores.

CONCLUSIONS

Taken together, these results suggest that a multilocus genetic composite of monoamine signaling relates to depression symptomatology through brain function associated with the experience of negative emotions. This research lays the groundwork for future studies that can investigate clinical outcomes and/or pharmacogenetic therapies in drug addiction and potentially other psychopathologies of emotion dysregulation.

Investigation of association of serotonin transporter and monoamine oxidase-A genes with Alzheimer's disease and depression in the VITA study cohort: a 90-month longitudinal study

Alzheimer's disease (AD) and depression (DE) are common psychiatric disorders strongly intertwined with one another. Nevertheless, etiology and early diagnosis of the disorders are still elusive. Several genetic variations have been suggested to associate with AD and DE, particularly in genes involved in the serotonergic system such as the serotonin transporter (SERT/SLC6A4), responsible for the removal from the synaptic cleft, and the monoamine-oxidase-A (MAOA), responsible for the presynaptic degradation of serotonin. Here, we attempt to characterize this pleiotropic effect for the triallelic SERT gene-linked polymorphic region (5HTTLPR) and for the MAOA-uVNTR, in participants in the Vienna-Transdanube-Aging (VITA)-study. The VITA-study is a community-based longitudinal study following a birth cohort (75 years old at baseline examination, n = 606) from Vienna for a period of 90 months with a regular follow-up interval of 30 months. Our main finding, confirming previous reports, is that the 5HTTLPR S-allele is a risk allele for DE (OR = 1.55 CI 95% 1.03-2.32) and its carriers had a steeper increase in SGDS sum score. No association to AD was found. MAOA-uVNTR did not associate with either AD or DE. However, in AD MAOA-uVNTR S-allele carriers a steeper increase of HAMD and STAI1 sum scores (P < 0.05) was observed. Although the VITA-study cohort is rather small with low power to detect gene alterations, the uniqueness of this very thoroughly investigated and homogenous cohort strengthens the results through exceptional data collection. Still, reinvestigation in a larger cohort similar to this, as well as a meta-analysis, is important to confirm these results.

Role of 5-HTTLPR polymorphism in the development of the inward/outward personality organization: a genetic association study

Reciprocity with primary caregivers affects subjects' adaptive abilities toward the construction of the most useful personal meaning organization (PMO) with respect to their developmental environment. Within cognitive theory the post-rationalist approach has outlined two basic categories of identity construction and of regulation of cognitive and emotional processes: the Outward and the Inward PMO. The presence of different, consistent clinical patterns in Inward and Outward subjects is paralleled by differences in cerebral activation during emotional tasks on fMRI and by different expression of some polymorphisms in serotonin pathways. Since several lines of evidence support a role for the 5-HTTLPR polymorphism in mediating individual susceptibility to environmental emotional stimuli, this study was conducted to investigate its influence in the development of the Inward/Outward PMO.

PMO was assessed and the 5-HTTLPR polymorphism investigated in 124 healthy subjects who were subdivided into an Inward (n = 52) and an Outward (n = 72) group.

Case-control comparisons of short allele (S) frequencies showed significant differences between Inwards and Outwards (p = 0.036, χ2 test; p = 0.026, exact test). Genotype frequencies were not significantly different although values slightly exceeded p≤0.05 (p = 0.056, χ2 test; p = 0.059, exact test). Analysis of the 5-HTTLPR genotypes according to the recessive inheritance model showed that the S/S genotype increased the likelihood of developing an Outward PMO (p = 0.0178, χ2 test; p = 0.0143, exact test; OR = 3.43, CI (95%) = 1.188–9.925). A logistic regression analysis confirmed the association between short allele and S/S genotypes with the Outward PMO also when gender and age were considered. However none of the differences remained significant after correction for multiple testing, even though using the recessive model they approach significance.

Overall our data seem to suggest a putative genetic basis for interindividual differences in PMO development.

The psychodynamic psychotherapist's guide to the interaction among sex, genes, and environmental adversity in the etiology of depression for women

From menarche to menopause, women are highly vulnerable to major depression. While biological and psychosocial differences between men and women have been established, the reason for the preponderance of depression in women has yet to be fully elucidated. Women may be predisposed to depressive illness because of biological factors related to brain structure, function, and the impact of reproductive life stages. They may also be at increased risk because they are differentially disadvantaged with respect to environmental stressors including interpersonal violence, socioeconomic instability, and caregiving burden, among others. However, not all women develop depression, nor do all individuals who suffer from adverse life events. This narrative review focuses on emerging research related to the interaction between sex, genetics, and environmental factors that may help offer clues about why some individuals suffer from depression, and why others may be resilient to this outcome. While many questions remain unanswered, the psychodynamic psychotherapist can use this information to help patients suffering from depression understand some of the complexities of the determinants of risk and resilience, with the goal of moving forward toward recovery.

Interaction between a serotonin transporter gene promoter region polymorphism and stress predicts depressive symptoms in Chinese adolescents: a multi-wave longitudinal study

BACKGROUND

The serotonin transporter (5-HTT) gene may play an important role in the onset and development of mental disorders. Past studies have tested whether a functional polymorphism in the 5-HTT gene linked promoter region (5-HTTLPR) moderated the association between stress and depressive symptoms, but the results of these studies were inconsistent. Thus, the aim of the current study was to examine the interaction between 5-HTTLPR and stress that predict depressive symptoms in Chinese adolescents.

METHODS

A total of 252 healthy adolescents (131 females and 121 males, aged from 14 to 18, mean = 16.00, standard deviation = 0.60) participated in this study. During the initial assessment, all participants completed the Center for Epidemiological Studies Depression Scale (CES-D) and Adolescent Life Events Questionnaire (ALEQ) and were genotyped for the 5-HTTLPR polymorphism. Participants subsequently completed CES-D and ALEQ once every three months during the subsequent 24 months. A multilevel model was used to investigate the 5-HTTLPR × stress interaction in predicting depressive symptoms.

RESULTS

The results indicated no main effect of 5-HTTLPR and a significant 5-HTTLPR × stress interaction in females only. Females with at least one 5-HTTLPR S allele exhibited more depressive symptoms under stressful situations. No significant 5-HTTLPR × stress interaction was found in males.

CONCLUSIONS

In Chinese adolescents, there are gender differences on the interaction between 5-HTTLPR and stress that predict depressive symptoms. The association between stress and depressive symptoms is moderated by 5-HTTLPR in Chinese female adolescents.

Epigenetic Modulation of Mood Disorders

BACKGROUND

Mood disorders are expressed in many heterogeneous forms, varying from anxiety to severe major clinical depression. The disorders are expressed in individual variety through manifestations governed by co-morbidities, symptom frequency, severity, and duration, and the effects of genes on phenotypes. The underlying etiologies of mood disorders consist of complex interactive operations of genetic and environmental factors. The notion of endophenotypes, which encompasses the markers of several underlying liabilities to the disorders, may facilitate efforts to detect and define, through staging, the genetic risks inherent to the extreme complexity of disease state.

AIMS

This review evaluates the role of genetic biomarkers in assisting clinical diagnosis, identification of risk factors, and treatment of mood disorders.

METHODS

Through a systematic assessment of studies investigating the epigenetic basis for mood disorders, the present review examines the interaction of genes and environment underlying the pathophysiology of these disorders.

RESULTS

The majority of research findings suggest that the notion of endophenotypes, which encompasses the markers of several underlying liabilities to the disorders, may facilitate efforts to detect and define, through staging, the genetic risks inherent to the extreme complexity of the disease states. Several strategies under development and refinement show the propensity for derivation of essential elements in the etiopathogenesis of the disorders affecting drug-efficacy, drug metabolism, and drug adverse effects, e.g., with regard to selective serotonin reuptake inhibitors. These include: transporter gene expression and genes encoding receptor systems, hypothalamic-pituitary-adrenal axis factors, neurotrophic factors, and inflammatory factors affecting neuroimmune function. Nevertheless, procedural considerations of pharmacogenetics presume the parallel investment of policies and regulations to withstand eventual attempts at misuse, thereby ensuring patient integrity.

CONCLUSIONS

Identification of genetic biomarkers facilitates choice of treatment, prediction of response, and prognosis of outcome over a wide spectrum of symptoms associated with affective states, thereby optimizing clinical practice procedures. Epigenetic regulation of primary brain signaling, e.g., serotonin and hypothalamic-pituitary-adrenal function, and factors governing their metabolism are necessary considerations. The participation of neurotrophic factors remains indispensable for neurogenesis, survival, and functional maintenance of brain systems.