The interaction of DRD2 and violent victimization on depression: an analysis by gender and race

A person-centered data analytic approach to dopaminergic polygenic moderation of child maltreatment exposure

The present study illustrates the utility of latent class analysis, a person-centered data analytic approach, as an innovative method for identifying naturally occurring patterns of polygenic risk, specifically within the dopaminergic system. Moreover, this study tests whether latent classes of polygenic variation moderate the effect of child maltreatment exposure on internalizing symptoms among African ancestry youth. African ancestry youth were selected for this study because youth of color are overrepresented in the child welfare system and because African ancestry individuals are significantly underrepresented in genomics research. Results identified three latent classes of dopaminergic gene variation. Class 1 was marked predominately by homozygous minor alleles, Class 2 was characterized by homozygous major and heterozygous presentations, and Class 3 was marked by heterozygous alleles on the DAT-1 single-nucleotide polymorphisms (SNPs) and a combination of homozygous major and minor alleles on the other SNPs. Results indicated that a greater number of maltreatment subtypes experienced were associated with higher internalizing symptoms only for children with the latent polygenic Class 2 pattern. This latent class was distinctly characterized by more homozygous major or heterozygous allelic presentations along all three DAT-1 SNPs. This significant latent polygenic class by environment interaction was replicated in an independent replication sample. Together, findings suggest that African ancestry children with a pattern of dopaminergic variation characterized by this specific combination of polygenic variation are more vulnerable to developing internalizing symptoms following maltreatment exposure, relative to their peers with other dopamine-related polygenic patterns.

Theorizing the Role of Dopaminergic Polymorphic Risk Alleles with Intermittent Explosive Disorder (IED), Violent/Aggressive Behavior and Addiction: Justification of Genetic Addiction Risk Severity (GARS) Testing

Scientific studies have provided evidence that there is a relationship between violent and aggressive behaviors and addictions. Genes involved with the reward system, specifically the brain reward cascade (BRC), appear to be associated with various addictions and impulsive, aggressive, and violent behaviors. In our previous research, we examined the Taq A1 allele (variant D2 dopamine receptor gene) and the DAT-40 base repeat (a variant of the dopamine transporter gene) in 11 Caucasian boys at the Brown School in San Marcus, Texas, diagnosed with intermittent explosive disorder. Thirty supernormal controls were screened to exclude several reward-deficit behaviors, including pathological violence, and genotyped for the DRD2 gene. Additionally, 91 controls were screened to exclude ADHD, pathological violence, alcoholism, drug dependence, and tobacco abuse, and their results were compared with DAT1 genotype results. In the schoolboys vs. supercontrols, there was a significant association with the D2 variant and a trend with the dopamine transporter variant. Results support our hypothesis and the involvement of at least two gene risk alleles with adolescent violent/aggressive behaviors. This study and the research presented in this paper suggest that violent/aggressive behaviors are associated with a greater risk of addiction, mediated via various genes linked to the BRC. This review provides a contributory analysis of how gene polymorphisms, especially those related to the brain reward circuitry, are associated with violent behaviors.

Examining how and why polygenic dopamine composite levels moderate adolescents' vulnerability to peer victimization

Extensive literature documents that dopaminergic genes play an important role in the link between adverse environments and adolescents' problem behavior. However, little is known about the potential mechanism underlying adolescents' vulnerability to peer victimization. The current study examined the effect of the interplay between a polygenic dopamine composite (i.e., COMT Val158Met and DRD2-141C Ins/Del polymorphisms) and peer victimization on adolescents' externalizing problems as well as the mediating role of emotion dysregulation in the interactive effects in a sample of 393 Chinese adolescents (Mean age = 14.71 years; 50.1% girls). A significant moderation of dopaminergic genetic composite was observed in girls but not in boys. In addition, emotion dysregulation partially explained the moderating effect of dopaminergic genes. Specifically, girls with genic composite indexing low dopamine activity reported a higher level of emotion dysregulation when faced with more peer victimization. More difficulties with emotion regulation, in turn, predicted more pronounced externalizing problems in girls. This study underscores polygenic underpinnings of adolescent vulnerability to negative peer experiences and suggests the importance of considering sex differences when investigating genic influence on the relationship between adverse environments and externalizing problems.

Intergenerational Transmission of Depression during Adolescence: The Mediating Roles of Hostile Attribution Bias, Empathic Concern, and Social Self-Concept

Few studies have empirically examined the role of peer microsystem in the intergenerational transmission of depression, and more importantly, little is known about the mechanisms underlying this potential pathway of intergenerational transmission. The purpose of the current study was to examine the sequential mediation effects of adolescent hostile attribution bias, empathic concern, and social self-concept on the association between maternal depression and adolescent depression. An urban Chinese sample of 761 mother-child dyads was investigated when the adolescents were in secondary school (M = 14.36 years, range =12.33-16.92 years, 52.3% female). The results provided evidence of cross-generational continuity in depression during adolescence, and the hypothesized sequential mediation model was supported. The findings highlight the importance of peer-related factors during the intergenerational transmission of depression and have important implications for interpersonal interventions that aim to prevent depression during adolescence. The limitations of the study and suggestions for future research are briefly discussed.

ADHD co-morbidities: A review of implication of gene × environment effects with dopamine-related genes

ADHD is a major burden in adulthood, where co-morbid conditions such as depression, substance use disorder and obesity often dominate the clinical picture. ADHD has substantial shared heritability with other mental disorders, contributing to comorbidity. However, environmental risk factors exist but their interaction with genetic makeup, especially in relation to comorbid disorders, remains elusive. This review for the first time summarizes present knowledge on gene x environment (GxE) interactions regarding the dopamine system. Hitherto, mainly candidate (GxE) studies were performed, focusing on the genes DRD4, DAT1 and MAOA. Some evidence suggest that the variable number tandem repeats in DRD4 and MAOA may mediate GxE interactions in ADHD generally, and comorbid conditions specifically. Nevertheless, even for these genes, common variants are bound to suggest risk only in the context of gender and specific environments. For other polymorphisms, evidence is contradictory and less convincing. Particularly lacking are longitudinal studies testing the interaction of well-defined environmental with polygenic risk scores reflecting the dopamine system in its entirety.

Sex Differences in Dopamine Receptors and Relevance to Neuropsychiatric Disorders

Dopamine is an important neurotransmitter that plays a key role in neuropsychiatric illness. Sex differences in dopaminergic signaling have been acknowledged for decades and have been linked to sex-specific heterogeneity in both dopamine-related behaviours as well as in various neuropsychiatric disorders. However, the overall number of studies that have evaluated sex differences in dopamine signaling, both in health and in these disorders, is low. This review will bring together what is known regarding sex differences in innate dopamine receptor expression and function, as well as highlight the known sex-specific roles of dopamine in addiction, depression, anxiety, schizophrenia, and attention deficit hyperactivity disorder. Due to differences in prognosis, diagnosis, and symptomatology between male and female subjects in disorders that involve dopamine signaling, or in responses that utilize pharmacological interventions that target dopamine receptors, understanding the fundamental sex differences in dopamine receptors is of vital importance for the personalization of therapeutic treatment strategies.

A knowledge-based multivariate statistical method for examining gene-brain-behavioral/cognitive relationships: Imaging genetics generalized structured component analysis

With advances in neuroimaging and genetics, imaging genetics is a naturally emerging field that combines genetic and neuroimaging data with behavioral or cognitive outcomes to examine genetic influence on altered brain functions associated with behavioral or cognitive variation. We propose a statistical approach, termed imaging genetics generalized structured component analysis (IG-GSCA), which allows researchers to investigate such gene-brain-behavior/cognitive associations, taking into account well-documented biological characteristics (e.g., genetic pathways, gene-environment interactions, etc.) and methodological complexities (e.g., multicollinearity) in imaging genetic studies. We begin by describing the conceptual and technical underpinnings of IG-GSCA. We then apply the approach for investigating how nine depression-related genes and their interactions with an environmental variable (experience of potentially traumatic events) influence the thickness variations of 53 brain regions, which in turn affect depression severity in a sample of Korean participants. Our analysis shows that a dopamine receptor gene and an interaction between a serotonin transporter gene and the environment variable have statistically significant effects on a few brain regions' variations that have statistically significant negative impacts on depression severity. These relationships are largely supported by previous studies. We also conduct a simulation study to safeguard whether IG-GSCA can recover parameters as expected in a similar situation.

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.

Association of Genetic Factors and Gene-Environment Interactions With Risk of Developing Posttraumatic Stress Disorder in a Case-Control Study

BACKGROUND

The dopamine receptor D2 (DRD2) and serotonin transporter (5-HTT) genes are associated with posttraumatic stress disorder (PTSD). However, it remains largely unknown whether these genes interact with environmental factors to affect the development of PTSD.

PURPOSE

The purpose of this study was to examine the associations of gene polymorphisms and gene-environment interactions with the risk of developing PTSD among adolescent earthquake survivors.

METHOD

A total of 183 adolescent survivors from an earthquake-stricken area participated in this study. Measures included a questionnaire about demographic characteristics and earthquake exposure, the PTSD Checklist-Civilian Version and the Structured Clinical Interview for Diagnostic and Statistical Manual of Mental Disorders, fourth edition disorders. Genotypes were analyzed by using the polymerase chain reaction-based restriction fragment length polymorphism.

RESULTS

The 5-HTTLPR and 5-HTTVNTR polymorphisms and earthquake exposure had statistically significant positive effects on PTSD. The interaction effects of 5-HTTLPR × Earthquake Exposure and 5-HTTVNTR × Earthquake Exposure were statistically significant.

CONCLUSION

The development of PTSD is the result not only of a genetic effect and environmental factors but also of the interactive effect between gene and environment.

The Dopamine D2 Receptor Polymorphism (DRD2 TaqIA) Interacts with Maternal Parenting in Predicting Early Adolescent Depressive Symptoms: Evidence of Differential Susceptibility and Age Differences

Most gene-environment interaction research on depression has largely focused on negative environment and to a lesser extent on positive environment. Moreover, to date few studies have directly examined G × E at different periods in development, particularly during early adolescence. The present study addressed these issues by examining the concurrent and prospective longitudinal effects of maternal parenting, DRD2 TaqIA polymorphism, and their interaction on adolescent depressive symptoms in a sample of 1026 Chinese adolescents (Mage = 11.33 ± 0.47 years at T1, 50.3% girls) in a three-wave longitudinal study from age 11 to 13. Results indicated that maternal positive and negative parenting significantly concurrently predicted adolescent depressive symptoms at all three waves, whereas TaqIA polymorphism had no main effect on depressive symptoms. TaqIA polymorphism interacted with negative parenting in predicting concurrent depressive symptoms at age 11 and 12. A1 carriers were more susceptible to negative parenting compared to A2A2 homozygotes, such that adolescents carrying A1 alleles experiencing high negative parenting reported more depressive symptoms but fared better when experiencing low negative parenting. However, the interaction became nonsignificant at age 13, indicating the interaction of TaqIA polymorphism and maternal parenting may vary with development. Also, there was no G × E effect on longitudinal change in depression. The findings provided evidence in support of the differential susceptibility hypothesis and shed light on the potential for dynamic change in gene-environment interactions over development.

Dopamine and glucose, obesity, and reward deficiency syndrome

Obesity as a result of overeating as well as a number of well described eating disorders has been accurately considered to be a world-wide epidemic. Recently a number of theories backed by a plethora of scientifically sound neurochemical and genetic studies provide strong evidence that food addiction is similar to psychoactive drug addiction. Our laboratory has published on the concept known as Reward Deficiency Syndrome (RDS) which is a genetic and epigenetic phenomena leading to impairment of the brain reward circuitry resulting in a hypo-dopaminergic function. RDS involves the interactions of powerful neurotransmitters and results in abnormal craving behavior. A number of important facts which could help translate to potential therapeutic targets espoused in this focused review include: (1) consumption of alcohol in large quantities or carbohydrates binging stimulates the brain’s production of and utilization of dopamine; (2) in the meso-limbic system the enkephalinergic neurons are in close proximity, to glucose receptors; (3) highly concentrated glucose activates the calcium channel to stimulate dopamine release from P12 cells; (4) a significant correlation between blood glucose and cerebrospinal fluid concentrations of homovanillic acid the dopamine metabolite; (5) 2-deoxyglucose (2DG), the glucose analog, in pharmacological doses is associated with enhanced dopamine turnover and causes acute glucoprivation. Evidence from animal studies and fMRI in humans support the hypothesis that multiple, but similar brain circuits are disrupted in obesity and drug dependence and for the most part, implicate the involvement of DA-modulated reward circuits in pathologic eating behaviors. Based on a consensus of neuroscience research treatment of both glucose and drug like cocaine, opiates should incorporate dopamine agonist therapy in contrast to current theories and practices that utilizes dopamine antagonistic therapy. Considering that up until now clinical utilization of powerful dopamine D2 agonists have failed due to chronic down regulation of D2 receptors newer targets based on novel less powerful D2 agonists that up-regulate D2 receptors seems prudent. We encourage new strategies targeted at improving DA function in the treatment and prevention of obesity a subtype of reward deficiency.

Hatching the behavioral addiction egg: Reward Deficiency Solution System (RDSS)™ as a function of dopaminergic neurogenetics and brain functional connectivity linking all addictions under a common rubric

BACKGROUND

Following the first association between the dopamine D2 receptor gene polymorphism and severe alcoholism, there has been an explosion of research reports in the psychiatric and behavioral addiction literature and neurogenetics. With this increased knowledge, the field has been rife with controversy. Moreover, with the advent of Whole Genome-Wide Studies (GWAS) and Whole Exome Sequencing (WES), along with Functional Genome Convergence, the multiple-candidate gene approach still has merit and is considered by many as the most prudent approach. However, it is the combination of these two approaches that will ultimately define real, genetic allelic relationships, in terms of both risk and etiology. Since 1996, our laboratory has coined the umbrella term Reward Deficiency Syndrome (RDS) to explain the common neurochemical and genetic mechanisms involved with both substance and non-substance, addictive behaviors.

METHODS

This is a selective review of peer-reviewed papers primary listed in Pubmed and Medline.

RESULTS

A review of the available evidence indicates the importance of dopaminergic pathways and resting-state, functional connectivity of brain reward circuits.

DISCUSSION

Importantly, the proposal is that the real phenotype is RDS and impairments in the brain's reward cascade, either genetically or environmentally (epigenetically) induced, influence both substance and non-substance, addictive behaviors. Understanding shared common mechanisms will ultimately lead to better diagnosis, treatment and prevention of relapse. While, at this juncture, we cannot as yet state that we have "hatched the behavioral addiction egg", we are beginning to ask the correct questions and through an intense global effort will hopefully find a way of "redeeming joy" and permitting homo sapiens live a life, free of addiction and pain.

Genetic Heterogeneity in Adolescents' Depressive Symptoms in Response to Victimization

This study had two objectives: first, to determine the degree to which experiences of victimization by peers during adolescence led to a subsequent rise in depressive symptoms, and second, to identify genetic markers that predict depressive reactivity to victimization. We used a cohort sequential design to obtain a longitudinal sample of 1,475 adolescents (3,263 observations) in Grades 8 to 12 (56% female; 47% Black, 46% White). Multilevel growth curve models were used to assess whether victimization predicted depressive symptoms 6 months later, beyond baseline trajectories for depressive symptoms. We modeled the interactive effects of peer victimization with three genetic polymorphisms (on 5-HTTLPR, DRD2 TaqIA, and BDNF Val66Met) on depressive symptoms. Although victimization predicted subsequent depressive symptoms, there was substantial heterogeneity in the magnitude of the effect of victimization. Val alleles, associated with higher brain-derived neurotrophic factor (BDNF) functioning, predicted more sensitivity to victimization. Neither DRD2 TaqIA, a marker associated with dopaminergic functioning, nor 5-HTTLPR, a marker associated with serotonin activity, was associated with sensitivity to victimization. The social stress of peer victimization triggers depressive symptoms most strongly in individuals who are homozygous for the Val allele on the BDNF Val/Met polymorphism. This polymorphism has been linked with sensitivity to social defeat in animal models. Future research should explore behavioral, cognitive, and emotional explanations of the effects of BDNF Val/Met on responsivity to victimization.

The DRD2 rs1800497 polymorphism increase the risk of mood disorder: evidence from an update meta-analysis

BACKGROUND

Growing studies have revealed the association between rs1800497 polymorphism in the dopamine receptor D2 (DRD2) and susceptibility to mood disorder (MD). However, the results remained inconsistent.

METHODS

To assess the effect of DRD2 rs1800497 polymorphism on MD. We performed a meta-analysis based on eight case-control studies, including a total of 2097 MD cases and 1681 controls. Summary odds ratios (OR) and corresponding 95% confidence intervals (CIs) for DRD2 rs1800497 polymorphism and MD risk were estimated.

RESULTS

Our meta-analysis indicated that DRD2 rs1800497 was associated with an increased MD risk, especially in Asians. Moreover, in the subgroup analysis by the type of MD, DRD2 rs1800497 polymorphism was observed to increase risk in BP.

LIMITATIONS

The results should be treated with caution for lacking of data to perform gene-gene and gene-environment interaction.

CONCLUSIONS

Our results indicated that polymorphism in DRD2 rs1800497 may play a role in development of MD.

A longitudinal examination of psychological, behavioral, academic, and relationship consequences of dating abuse victimization among a primarily rural sample of adolescents

PURPOSE

It is widely held that being victimized by a dating partner during adolescence has negative consequences, yet few longitudinal studies have examined those consequences. This longitudinal study examined the effects of psychological and physical (including sexual) dating abuse victimization on internalizing symptoms, substance use, academic aspirations and grades, and relationships with friends and family.

METHODS

This four-wave longitudinal study (N = 3,328), conducted in two rural North Carolina counties, spanned grades 8 to 12. Random coefficient analyses were used to examine prospective lagged effects of each type of dating abuse on each outcome and to examine sex and grade as moderators of lagged effects.

RESULTS

Consequences varied by type of dating abuse experienced and sex. For both boys and girls, psychological victimization predicted increased alcohol use and physical victimization predicted increased cigarette use. For girls, physical victimization predicted increased marijuana use, and psychological victimization predicted increased internalizing symptoms; the latter effect was only marginally significant for boys. Physical victimization marginally predicted decreases in the number of close friends for boys. Neither type of victimization predicted increased family conflict or decreased academic aspirations or grades, nor was there evidence that consequences varied by grade.

CONCLUSIONS

Although causation cannot be concluded with longitudinal designs, our findings suggest that being victimized by a dating partner may result in detrimental consequences for adolescents. The findings demonstrate the importance of identifying and implementing evidence-based interventions for preventing dating abuse, including efforts to prevent psychological abuse specifically.

Gene × environment interactions in the prediction of response to antidepressant treatment

Major depressive disorder (MDD) is responsible for an increasing individual and global health burden. Extensive research on the genetic disposition to develop MDD and to predict the response to antidepressant treatment has yet failed to identify strong genetic effects. The concept of gene × environment interaction takes into account that environmental factors have been identified as important components in the development of MDD and combines both, genetic predisposition and environmental exposure, to elucidate complex traits such as MDD. Here, we review the current research on gene × environment interactions with regard to the development of MDD as well as response to antidepressant treatment. We hypothesize that gene × environment interactions delineate specific biological subtypes of depression and that individuals with such pathophysiological distinct types of depression will likely respond to different treatments. The elucidation of gene × environment interactions may thus not only help to understand the pathophysiology of MDD but could also provide markers for a personalized antidepressant therapy.

Interaction of the TaqIA polymorphism and poor parental socialization on changes in adolescent marijuana use

The current study uses data from the genetic subsample from the National Longitudinal Study of Adolescent Health (Add Health) in waves I and II (ages of 11-19 and 12-20 respectively) to investigate the interaction of the TaqIA polymorphism and poor parental socialization on changes in adolescent marijuana use. Results reveal that TaqIA interacts with poor parental rule setting, but not quality of mother-child communication, to influence changes in marijuana use. Adolescents who are homozygous for the A1 and whose parents allow the youth to set their own curfew experience significant increases in marijuana use during adolescence. In contrast, youths with the A1/A1 genotype whose parents do not allow the adolescent to set their own curfew experience significant decreases in the frequency of marijuana use. These results suggest that direct parental social control may effectively suppress the genetic risk of the A1/A1 genotype on marijuana use in adolescence. The study's limitations are noted.

Research review: gene-environment interaction research in youth depression - a systematic review with recommendations for future research

BACKGROUND

Depression is a major public health problem among youth, currently estimated to affect as many as 9% of US children and adolescents. The recognition that both genes (nature) and environments (nurture) are important for understanding the etiology of depression has led to a rapid growth in research exploring gene-environment interactions (GxE). However, there has been no systematic review of GxE in youth depression to date.

METHODS

The goal of this article was to systematically review evidence on the contribution of GxE to the risk of child and adolescent depression. Through a search of PubMed and PsycINFO databases to 1 April 2010, we identified 20 candidate gene-environment interaction studies focused on depression in youth (up to age 26) and compared each study in terms of the following characteristics: research design and sample studied; measure of depression and environment used; genes explored; and GxE findings in relation to these factors.

RESULTS

In total, 80% of studies (n = 16) found at least one significant GxE association. However, there was wide variation in methods and analyses adopted across studies, especially with respect to environmental measures used and tests conducted to estimate GxE. This heterogeneity made it difficult to compare findings and evaluate the strength of the evidence for GxE.

CONCLUSIONS

The existing body of GxE research on depression in youth contains studies that are conceptually and methodologically quite different, which contributes to mixed findings and makes it difficult to assess the current state of the evidence. To decrease this heterogeneity, we offer 20 recommendations that are focused on: (a) reporting GxE research; (b) testing and reporting GxE effects; (c) conceptualizing, measuring and analyzing depression; (d) conceptualizing, measuring and analyzing environment; (e) increasing power to test for GxE; and (f) improving the quality of genetic data used. Although targeted to GxE research on depression, these recommendations can be adopted by GxE researchers focusing on other mental health outcomes.

Interaction of early environment, gender and genes of monoamine neurotransmission in the aetiology of depression in a large population-based Finnish birth cohort

Objectives Depression is a worldwide leading cause of morbidity and disability. Genetic studies have recently begun to elucidate its molecular aetiology. The authors investigated candidate genes of monoamine neurotransmission and early environmental risk factors for depressiveness in the genetically isolated population-based Northern Finland Birth Cohort 1966 (12 058 live births). Design The authors ascertained and subdivided the study sample (n=5225) based on measures of early development and of social environment, and examined candidate genes of monoamine neurotransmission, many of which have shown prior evidence of a gene-environment interaction for affective disorders, namely SLC6A4, TPH2, COMT, MAOA and the dopamine receptor genes DRD1-DRD5. Results and conclusion The authors observed no major genetic effects of the analysed variants on depressiveness. However, when measures of early development and of social environment were considered, some evidence of interaction was observed. Allelic variants of COMT interacted with high early developmental risk (p=0.005 for rs2239393 and p=0.02 for rs4680) so that the association with depression was detected only in individuals at high developmental risk group (p=0.0046 and β=0.056 for rs5993883-rs2239393-rs4680 risk haplotype CGG including Val158), particularly in males (p=0.0053 and β=0.083 for the haplotype CGG). Rs4274224 from DRD2 interacted with gender (p=0.017) showing a significant association with depressiveness in males (p=0.0006 and β=0.0023; p=0.00005 and β=0.069 for rs4648318-rs4274224 haplotype GG). The results support the role of genes of monoamine neurotransmission in the aetiology of depression conditional on environmental risk and sex, but not direct major effects of monoaminergic genes in this unselected population.

Dysfunctional attitudes and the serotonin transporter promoter polymorphism (5-HTTLPR)

Dysfunctional attitudes may be one phenotype by which genes increase risk for depression. Building on research demonstrating associations between serotonin abnormalities and dysfunctional attitudes, we examined the covariation between dysfunctional attitudes and the serotonin transporter gene-linked polymorphic region (5-HTTLPR). In a sample of nondepressed young adults (N=131), people with one or two copies of the low-expressing alleles reported stronger endorsement of dysfunctional attitudes regarding performance evaluation than people who were homozygous for the high-expressing alleles; there was no association between the 5-HTTLPR polymorphism and dysfunctional attitudes regarding approval by others. These results add to the literature linking the 5-HTTLPR polymorphism and cognitive vulnerabilities for depression.

DRD2/ANKK1 TaqI A polymorphism affects corticostriatal activity in response to negative affective facial stimuli

DRD2/ANKK1 TaqI A polymorphism has been suggested to be involved in a reward-related psychiatric disorders. However, the effect of Dopamine receptor D2 (DRD2) on emotional processing has not been investigated yet. We investigated the possible relationship between DRD2/ANKK1 TaqI A polymorphism and corticostriatal response to negative facial stimuli using functional magnetic resonance imaging. All participants were genotyped with regard to the DRD2/ANKK1 TaqI A polymorphism. Our results suggest an association between the DRD2/ANKK1 TaqI A polymorphism and activations in the putamen, the anterior cingulate cortex, and amygdala in response to negative facial stimuli. Furthermore, molecular heterosis at the TaqI polymorphism of DRD2/ANKK1 may play an important role in affective regulation by corticostriatal pathway.

Using gene-environment interactions to target personalized treatment in mood disorder

Mood disorders account for a substantial social and financial burden on society. Although considerable efforts to delineate the underlying pathophysiological pathways have been undertaken during the last decades, only very limited progress on diagnostic and treatment algorithms have been achieved. High hopes have been put into genetics research to elucidate the pathogenesis of mood disorders, but so far, only small and inconsistent associations could be reported. Epidemiologic and family studies have always emphasized the importance of environmental factors; especially the impact of childhood trauma in mood disorders and more recently a number of specific gene-environment interactions have been reported. It is thus likely that the combination of a patient's life history and genetic susceptibility as well as other laboratory markers might provide a better insight into mental diseases and their treatment options. In this article, we discuss the concept of gene-environment interactions in major depression and their putative role in treatment response and personalized therapy.