Dopamine 2 receptor C957T and catechol-o-methyltransferase Val158Met polymorphisms are associated with treatment response in electroconvulsive therapy

Assessment of genetic variants in D2 dopamine receptor (DRD2) gene as risk factors for post-traumatic stress disorder (PTSD) and major depressive disorder (MDD): A systematic review and meta-analysis

BACKGROUND

Many studies have performed assessments of genetic variants in the D2 dopamine receptor (DRD2) gene as risk factors for post-traumatic stress disorder (PTSD) and major depressive disorder (MDD). However, the results are inconsistent. This meta-analysis aimed to systematically summarize published data to evaluate the reliable association between the DRD2 genetic variants and the risk of PTSD and MDD.

METHODS

A systematic literature search was conducted using the Web of Science, PubMed, Google Scholar, Excerpta Medica Database (EMBASE), Springer, ScienceDirect, Wiley Online Library, Cochrane Central Register of Controlled Trials, Chinese Biomedical Literature Database (CBM), WANFANG Data, CQVIP, and Chinese National Knowledge Infrastructure (CNKI) databases before January 1st, 2022.

RESULTS

A total of 27 genetic variants in the DRD2 gene were retrieved, and 7 of them met the inclusion criteria for meta-analysis. Our meta-analysis results indicated that the rs1800497 (TaqIA) polymorphism was significantly associated with the increased risk of PTSD (Dominant model (A1A1 + A1A2 vs. A2A2): OR = 1.49, 95 % CI, 1.08-2.04 Z = 2.46, P = 0.014). Subgroup analysis for ethnicity suggested that a significantly increased risk of PTSD was observed in Asians (Dominant model (A1A1 + A1A2 vs. A2A2): OR = 1.39, 95 % CI, 1.08-1.79, Z = 2.60, P = 0.009) and Caucasians (Dominant model (A1A1 + A1A2 vs. A2A2): OR = 1.87, 95 % CI 1.02-3.41, Z = 2.04, P = 0.042). Meanwhile, we detected significant association strengths between the rs1799978 and rs2075652 polymorphisms in the DRD2 gene and MDD (for rs1799978, Homozygote comparison (GG vs. AA): OR = 0.60, 95 % CI = 0.37-0.97, Z = 2.08, P = 0.038; for rs2075652, Homozygote comparison (AA vs. GG): OR = 1.82, 95 % CI = 1.32-2.50, Z = 3.67, P < 0.001). Our cumulative meta-analyses indicated a continuous trend toward association strength with PTSD and MDD.

CONCLUSIONS

This meta-analysis indicated that genetic variants in the DRD2 gene might potentially contribute to genetic susceptibility for PTSD and MDD. The utilization of DRD2 genetic variants as risk factors for PTSD and MDD requires further validation by large well-designed case-control studies.

Blues in the Brain and Beyond: Molecular Bases of Major Depressive Disorder and Relative Pharmacological and Non-Pharmacological Treatments

Despite the extensive research conducted in recent decades, the molecular mechanisms underlying major depressive disorder (MDD) and relative evidence-based treatments remain unclear. Various hypotheses have been successively proposed, involving different biological systems. This narrative review aims to critically illustrate the main pathogenic hypotheses of MDD, ranging from the historical ones based on the monoaminergic and neurotrophic theories, through the subsequent neurodevelopmental, glutamatergic, GABAergic, inflammatory/immune and endocrine explanations, until the most recent evidence postulating a role for fatty acids and the gut microbiota. Moreover, the molecular effects of established both pharmacological and non-pharmacological approaches for MDD are also reviewed. Overall, the existing literature indicates that the molecular mechanisms described in the context of these different hypotheses, rather than representing alternative ones to each other, are likely to contribute together, often with reciprocal interactions, to the development of MDD and to the effectiveness of treatments, and points at the need for further research efforts in this field.

Novel candidate genes for ECT response prediction-a pilot study analyzing the DNA methylome of depressed patients receiving electroconvulsive therapy

Background

Major depressive disorder (MDD) represents a serious global health concern. The urge for efficient MDD treatment strategies is presently hindered by the incomplete knowledge of its underlying pathomechanism. Despite recent progress (highlighting both genetics and the environment, and thus DNA methylation, to be relevant for its development), 30–50% of MDD patients still fail to reach remission with standard treatment approaches. Electroconvulsive therapy (ECT) is one of the most powerful options for the treatment of pharmacoresistant depression; nevertheless, ECT remission rates barely reach 50% in large-scale naturalistic population-based studies. To optimize MDD treatment strategies and enable personalized medicine in the long- term, prospective indicators of ECT response are thus in great need. Because recent target-driven analyses revealed DNA methylation baseline differences between ECT responder groups, we analyzed the DNA methylome of depressed ECT patients using next-generation sequencing. In this pilot study, we did not only aim to find novel targets for ECT response prediction but also to get a deeper insight into its possible mechanism of action.

Results

Longitudinal DNA methylation analysis of peripheral blood mononuclear cells isolated from a cohort of treatment-resistant MDD patients (n = 12; time points: before and after 1st and last ECT, respectively) using a TruSeq-Methyl Capture EPIC Kit for library preparation, led to the following results: (1) The global DNA methylation differed neither between the four measured time points nor between ECT responders (n = 8) and non-responders (n = 4). (2) Analyzing the DNA methylation variance for every probe (=1476812 single CpG sites) revealed eight novel candidate genes to be implicated in ECT response (protein-coding genes: RNF175, RNF213, TBC1D14, TMC5, WSCD1; genes encoding for putative long non-coding RNA transcripts: AC018685.2, AC098617.1, CLCN3P1). (3) In addition, DNA methylation of two CpG sites (located within AQP10 and TRERF1) was found to change during the treatment course.

Conclusions

We suggest ten novel candidate genes to be implicated in either ECT response or its possible mechanism. Because of the small sample size of our pilot study, our findings must be regarded as preliminary.

Association between COMT gene Val108/158Met and antidepressive treatment response: A meta-analysis

Multiple antidepressive treatment methods are widely used in the clinic, but different patients showed considerable differences in response to the same treatment. The catechol-O-methyltransferase (COMT) rs4680 polymorphism is involved in the antidepressive treatment reaction; however, the results in different studies are inconsistent. Thus, we performed a meta-analysis to explore the association of the COMT rs4680 polymorphism with the treatment response in major depressive disorder (MDD) patients. An online search was performed through PubMed, EMBASE and the Cochrane library up to December 2018. The odds ratios (ORs), 95% confidence intervals (95% CI) and heterogeneity were calculated in four genetic models. Subgroup analysis and Galbraith plot were carried out to detect the potential source of heterogeneity. Sensitivity and publication bias analyses were performed to identify the reliability of the results. A total of 11 studies involving 2845 individuals were included in this meta-analysis. The results of the subgroup analysis indicated that patients who carried the G allele had remission or a better response to electroconvulsive therapy (ECT) in four genetic models. Excluding the studies that might lead to heterogeneity, overall ORs were recalculated, and no obvious association between rs4680 polymorphism and therapeutic reaction was detected in the allelic, recessive and additive models. In the dominant model, COMT rs4680 variants showed significant associations with antidepressive treatment, but the result was highly dependent on the individual study. In addition, the patients with the GG or AG + GG genotype in comparison to AA were associated with a better response to ECT treatment. However, due to the small number of studies using ECT treatment, we suggest that more research should be performed to verify this result.

Neurophysiology and genetics of burning mouth syndrome

BACKGROUND AND AIMS

Neuropathic mechanisms are involved in burning mouth syndrome (BMS), and variation of the dopamine D2 receptor (DRD2) gene contributes to experimental pain perception. We investigated whether neurophysiologic findings differ in BMS patients compared to healthy controls, and whether 957C>T polymorphism of the DRD2 gene influences thermal sensitivity or pain experience in BMS.

METHODS

Forty-five BMS patients (43 women), mean age 62.5 years, and 32 healthy controls (30 women), mean age 64.8 years, participated. Patients estimated pain intensity, interference, suffering and sleep with Numeric Rating Scale. Blink reflex tests of the supraorbital (SON), mental (MN) and lingual (LN) nerves, and thermal quantitative sensory testing were done. The results were analysed with ANOVA. DRD2 gene 957C>T polymorphism was determined in 31 patients, and its effects on neurophysiologic and clinical variables were analysed.

RESULTS

Cool (p = 0.0090) and warm detection thresholds (p = 0.0229) of the tongue were higher in BMS patients than controls. The stimulation threshold for SON BR was higher in patients than in controls (p = 0.0056). The latencies of R2 component were longer in BMS patients than in controls (p = 0.0005) at the SON distribution. Habituation of SON BR did not differ between the groups. The heat pain thresholds were highest (p = 0.0312) in homozygous patients with 957TT, who also reported most interference (p = 0.0352) and greatest suffering (p = 0.0341). Genotype 957CC associated with sleep disturbances (p = 0.0254).

CONCLUSIONS

Burning mouth syndrome patients showed thermal hypoesthesia within LN distribution compatible with small fibre neuropathy. The DRD2 957C>T genotype influences perception and experience of BMS pain.

SIGNIFICANCE

The results confirm earlier findings of neuropathic pain in BMS. The DRD2 957 C>T genotype influences perception and experience of clinical pain in BMS.

Effect of electroconvulsive therapy on brain-derived neurotrophic factor levels in patients with major depressive disorder

OBJECTIVES

Brain-derived neurotrophic factor (BDNF) has been associated with depression and its treatment response. The aim of the present study was to explore the effect of electroconvulsive therapy (ECT) on serum and plasma BDNF levels and change of Montgomery-Asberg Depression Rating Scale (MADRS) and their associations in patients with major depressive disorder (MDD).

METHODS

The study included thirty patients suffering from MDD. Their serum and plasma BDNF levels were examined before ECT (baseline) and after the first, fifth, and last ECT session. The severity of the depression and the response to ECT were measured with MADRS.

RESULTS

Electroconvulsive therapy caused no significant changes in serum BDNF levels. Plasma BDNF levels decreased during the fifth ECT session between the baseline and the 2-hr samples (p = 0.019). No associations were found between serum or plasma BDNF levels and remission. The correlations between plasma and serum BDNF levels in each measurement varied between 0.187 and 0.636.

CONCLUSIONS

Neither serum nor plasma BDNF levels were systematically associated with the clinical remission. However, the plasma BDNF levels somewhat varied during the ECT series. Therefore, the predictive value of BDNF for effects of ECT appears to be at least modest.

Potential Mechanisms Underlying the Therapeutic Effects of Electroconvulsive Therapy

In spite of the extensive application of electroconvulsive therapy (ECT), how it works remains unclear. So far, researchers have made great efforts in figuring out the mechanisms underlying the effect of ECT treatment via determining the levels of neurotransmitters and cytokines and using genetic and epigenetic tools, as well as structural and functional neuroimaging. To help address this question and provide implications for future research, relevant clinical trials and animal experiments are reviewed.

Meta-analysis of the COMT Val158Met polymorphism in major depressive disorder: the role of gender

OBJECTIVES

Many studies have reported an association of the COMT Val158Met polymorphism and major depressive disorder (MDD), although with conflicting results. The role of gender is a possible modulator. To overcome the problem of poor sample size detecting genes of small effect, we perform a meta-analysis of the current literature, investigating the influence of the COMT Val158Met polymorphism on the pathogenesis of MDD, with a major focus on the effect of gender.

METHODS

Out of 977 retrieved articles, 21 included case-control studies allowed the analysis of 9005 patients with MDD and 12,095 controls. Allelic and genotypic pooled odds ratios (OR) were calculated for the total sample and gender-subgroups.

RESULTS

In the absence of publication bias, allelic and genotypic analyses showed no significant association in the total sample, as well as in gender-specific subgroups. Sensitivity analysis did not alter the ORs.

CONCLUSIONS

The results imply a complex nature of the genotype × phenotype interaction. Further studies of the COMT gene or the locus remain to be justified given the important positional and functional relevance and the plethora of gender-specific findings. A possible way to further dissect this topic is shifting the focus to gene-based or genome-wide analyses of intermediate phenotypes.

Genetic polymorphisms and the adequacy of brain stimulation: state of the art

INTRODUCTION

Heterogeneity of therapeutic response to brain stimulation techniques has inspired scientists to uncover the secrets to success or failure of these projects. Genetic polymorphisms are one of the major causes of this heterogeneity.

AREAS COVERED

More than twenty genetic variants within more than ten genes (e.g. BDNF, COMT, DRD2, TRPV1, 5-HT1A, 5-HHT, P2RX7, VEGF, TPH1, TPH2, ACE, APOE, GNB3, NET, NMDA receptors, and RGS4) have been investigated, among which the BDNF gene and its polymorphism, Val66Met, is the best documented variant. We review the genotypic combinations, which are reported to interact with the work of brain stimulation, of which the DRD2 C957T polymorphism is the most prominent type. Finally, implications of transcranial magnetic stimulation in deciphering the interaction between genetic background (e.g. SCN1A and 5-HTT) and drugs (e.g. carbamazepine and citalopram) at the cortical excitability level is explained. Expert commentary: Studies are ongoing to find missing factors responsible for heterogeneity of response to brain stimulation techniques. Further knowledge about genetic factors affecting the therapeutic response to brain stimulation techniques might provide helpful guidelines for choosing ideal candidates for treatment.

Influence of GRIK4 genetic variants on the electroconvulsive therapy response

Several lines of evidence have shown the involvement of the glutamatergic system in the function of electroconvulsive therapy (ECT). In particular, patients with treatment resistant depression (TRD) and chronic depression have lower levels of glutamate/glutamine than controls, and ECT can reverse this deficit. Genetic factors might contribute to modulating the mechanisms underlying ECT. This study aimed to evaluate the relationship between three polymorphisms (rs1954787, rs4936554 and rs11218030) of the glutamate receptor ionotropic kainate 4 (GRIK4) gene and responsiveness to ECT treatment in a sample of one hundred individuals, TRD or depressive Bipolar Disorder patients resistant to pharmacological treatments. The results revealed that GRIK4 variants were significantly associated with the response to ECT. In particular, we found that patients carrying the G allele of the GRIK4 rs11218030 had a significantly poorer response to ECT (p=2.71×10(-4)), showing five times the risk of relapse after ECT compared to the AA homozygotes. Analogously, patients carrying the GG rs1954787 genotype and rs4936554A allele carriers presented a double risk of lack of response after ECT (p=0.013 and p=0.040, respectively). In conclusion, the current study provides new evidence, indicating that some GRIK4 variants modulate the response to ECT in patients with depression resistant to treatment, suggesting a role for kainate receptor modulation.

Genetic mechanisms of electroconvulsive therapy response in depression

Electroconvulsive therapy (ECT) is known to be one of the most effective treatments for managing depression and other severe mental illnesses. Nevertheless, the exact mechanisms underlying response to ECT remain uncertain. This mini-review presents clinical findings regarding the role of genetic factors in the aetiology of the ECT response. Studies on the role of variation in the catechol-O-methyltransferase (COMT) gene; other dopamine-, serotonin-, and G-protein-related genes; brain-derived neurotrophic factor (BDNF); apolipoprotein E (APOE); angiotensin I-converting enzyme (ACE) and vascular endothelial growth factor (VEGF) genes in mediating response to ECT are summarized. The existing data support the notion that some genetic factors-particularly the functional COMT val158met polymorphism-may play a role in the magnitude of clinical response to ECT, and thus could serve as potential biomarkers for future personalized treatment approaches. However, much of the work to date is preliminary, and large-scale confirmatory studies are still needed. Copyright © 2016 John Wiley & Sons, Ltd.

Meta-Analysis of the COMT Val158Met Polymorphism in Major Depressive Disorder: Effect of Ethnicity

The COMT (catechol-O-methyltransferase) Val158Met polymorphism (rs4680) is a potential susceptibility variant for major depressive disorder (MDD). Although many genetic studies have examined the association between MDD and this polymorphism, the results were inconclusive. In the present study, we conducted a series of meta-analyses of samples consisting of 2905 MDD cases and 2403 controls with the goal of determining whether this variant indeed has any effect on MDD. We revealed a significant association in the comparison of Val/Val + Val/Met vs. Met/Met (OR =1.180; 95 % CI = 1.019, 1.367; P = 0.027), Val/Met vs. Val/Val (OR =1.18; 95 % CI = 1.038, 1.361; P = 0.013), and Val/Met vs. Met/Met (OR =1.229; 95 % CI = 1.053, 1.435; P = 0.009). Further meta-analyses of samples with European ancestry demonstrated a significant association of this SNP with MDD susceptibility in Val/Val + Val/Met vs. Met/Met (OR =1.231, 95 % CI = 1.046, 1.449; P = 0.013) and Val/Met vs. Met/Met (OR =1.284, 95 % CI = 1.050, 1.484; P = 0.012). For the samples with East Asian ancestry, we found a significant association in both allelic (Val vs. Met: OR =0.835; 95 % CI = 0.714, 0.975; P = 0.023) and genotypic (Met/Met + Val/Met vs. Val/Val: OR =1.431, 95 % CI = 1.143, 1.791; P = 0.002; Val/Met vs. Val/Val: OR =1.482, 95 % CI = 1.171, 1.871; P = 0.001) analyses. No evidence of heterogeneity among studies or publication bias was observed. Together, our results indicate that the COMT Val158Met polymorphism is a vulnerability factor for MDD with distinct effects in different ethnic populations.

NCAM1-TTC12-ANKK1-DRD2 gene cluster and the clinical and genetic heterogeneity of adults with ADHD

Dysfunctions of the dopaminergic system have been implicated on the etiology of Attention Deficit/Hyperactivity Disorder (ADHD). Meta-analyses addressing the association of the dopamine receptor D2 (DRD2) gene and ADHD were inconclusive due to excessive heterogeneity across studies. Both the great phenotypic heterogeneity of ADHD and the complexity of the genomic region where DRD2 is located could contribute to the inconsistent findings. Most previous DRD2 studies focused on the well-known Taq1A (rs1800497) SNP, which is actually placed in a neighbor gene (ANKK1). These two genes, together with NCAM1 and TTC12, form the NTAD gene cluster on Chr11q22-23. In order to address the reasons for the high heterogeneity previously reported on DRD2 effects on ADHD, this study investigates the role of NTAD variants on ADHD susceptibility in adults and on the modulation of comorbidity and personality profiles in these patients. Functional polymorphisms from NTAD were analyzed, both individually and in haplotypes, on a sample of 520 adults with ADHD and 630 non-ADHD controls. No direct association of NTAD variants with ADHD susceptibility itself was observed. However, different NTAD polymorphisms and haplotypes were associated to various phenotypes relevant to the clinical heterogeneity of ADHD, including Major Depressive Disorder, Generalized Anxiety Disorder, and Harm Avoidance and Persistence temperament scores. Therefore, these findings represent a possible explanation for the multiple conflicting findings regarding polymorphisms in this genomic region in psychiatry. The NTAD cluster may comprise a variety of independent molecular influences on various brain and behavior characteristics eventually associated with ADHD comorbidities and personality traits. © 2015 Wiley Periodicals, Inc.

Pharmacogenetics in electroconvulsive therapy and adjunctive medications

Electroconvulsive therapy (ECT) has shown apparent efficacy in treatment of patients with depression and other mental illnesses who do not respond to psychotropic medications or need urgent control of their symptoms. Pharmacogenetics contributes to an individual's sensitivity and response to a variety of drugs. Clinical insights into pharmacogenetics of ECT and adjunctive medications not only improves its safety and efficacy in the indicated patients, but can also lead to the identification of novel treatments in psychiatric disorders through understanding of potential molecular and biological mechanisms involved. In this review, we explore the indications of pharmacogenetics role in safety and efficacy of ECT and present the evidence for its role in patients with psychiatric disorders undergoing ECT.

Early intervention following trauma may mitigate genetic risk for PTSD in civilians: a pilot prospective emergency department study

BACKGROUND

Civilian posttraumatic stress disorder (PTSD) and combat PTSD are major public health concerns. Although a number of psychosocial risk factors have been identified related to PTSD risk, there are no accepted, robust biological predictors that identify who will develop PTSD or who will respond to early intervention following trauma. We wished to examine whether genetic risk for PTSD can be mitigated with an early intervention.

METHOD

65 emergency department patients recruited in 2009-2010 at Grady Memorial Hospital in Atlanta, Georgia, who met criterion A of DSM-IV PTSD received either 3 sessions of an exposure intervention, beginning in the emergency department shortly after trauma exposure or assessment only. PTSD symptoms were assessed 4 and 12 weeks after trauma exposure. A composite additive risk score was derived from polymorphisms in 10 previously identified genes associated with stress-response (ADCYAP1R1, COMT, CRHR1, DBH, DRD2, FAAH, FKBP5, NPY, NTRK2, and PCLO), and gene x treatment effects were examined. The intervention included 3 sessions of imaginal exposure to the trauma memory and additional exposure homework. The primary outcome measure was the PTSD Symptom Scale-Interview Version or DSM-IV-based PTSD diagnosis in patients related to genotype and treatment group.

RESULTS

A gene x intervention x time effect was detected for individual polymorphisms, in particular the PACAP receptor, ADCYAP1R1, as well as with a combined genotype risk score created from independent SNP markers. Subjects who did not receive treatment had higher symptoms than those who received intervention. Furthermore, subjects with the "risk" genotypes who did not receive intervention had higher PTSD symptoms compared to those with the "low-risk" or "resilience" genotypes or those who received intervention. Additionally, PTSD symptoms correlated with level of genetic risk at week 12 (P < .005) in the assessment-only group, but with no relationship in the intervention group, even after controlling for age, sex, race, education, income, and childhood trauma. Using logistic regression, the number of risk alleles was significantly associated with likelihood of PTSD diagnosis at week 12 (P < .05).

CONCLUSIONS

This pilot prospective study suggests that combined genetic variants may serve to predict those most at risk for developing PTSD following trauma. A psychotherapeutic intervention initiated in the emergency department within hours of the trauma may mitigate this risk. The role of genetic predictors of risk and resilience should be further evaluated in larger, prospective intervention and prevention trials.

TRIAL REGISTRATION

ClinicalTrials.gov identifier: NCT00895518.

Assessment of genetic and nongenetic interactions for the prediction of depressive symptomatology: an analysis of the Wisconsin Longitudinal Study using machine learning algorithms

OBJECTIVES

We examined depression within a multidimensional framework consisting of genetic, environmental, and sociobehavioral factors and, using machine learning algorithms, explored interactions among these factors that might better explain the etiology of depressive symptoms.

METHODS

We measured current depressive symptoms using the Center for Epidemiologic Studies Depression Scale (n = 6378 participants in the Wisconsin Longitudinal Study). Genetic factors were 78 single nucleotide polymorphisms (SNPs); environmental factors-13 stressful life events (SLEs), plus a composite proportion of SLEs index; and sociobehavioral factors-18 personality, intelligence, and other health or behavioral measures. We performed traditional SNP associations via logistic regression likelihood ratio testing and explored interactions with support vector machines and Bayesian networks.

RESULTS

After correction for multiple testing, we found no significant single genotypic associations with depressive symptoms. Machine learning algorithms showed no evidence of interactions. Naïve Bayes produced the best models in both subsets and included only environmental and sociobehavioral factors.

CONCLUSIONS

We found no single or interactive associations with genetic factors and depressive symptoms. Various environmental and sociobehavioral factors were more predictive of depressive symptoms, yet their impacts were independent of one another. A genome-wide analysis of genetic alterations using machine learning methodologies will provide a framework for identifying genetic-environmental-sociobehavioral interactions in depressive symptoms.

Dopamine D₃ receptor gene variation: impact on electroconvulsive therapy response and ventral striatum responsiveness in depression

Dysfunction of dopamine D₃ receptors, particularly in the mesocorticolimbic system, has been linked to the pathogenesis of major depression. Preclinical data show enhanced D₃ receptor binding in the striatum upon antidepressant medication and electroconvulsive therapy (ECT). Thus, the potential impact of dopamine D₃ receptor gene (DRD3) variation on ECT outcome in treatment-resistant major depression was evaluated by applying a combined molecular and imaging genetic approach. Altogether, 10 representative variants covering 95.4% of DRD3 gene variation were investigated for association with response to ECT in a sample of 104 (71 female, 33 male) Caucasian patients with pharmacorefractory major depression. Additionally, ventral striatum responsiveness to happy faces was assessed in two independent samples of depressed patients (total N=54) by means of functional magnetic resonance imaging at 3 T. Significant association of DRD3 rs3732790, rs3773679 and rs9817063 variants with response (uncorrected p=0.02-0.03) and remission (uncorrected p=0.01) after ECT was discerned. Logistic regression analyses revealed association of rs3732790 (uncorrected p=0.009; corrected p=0.045) and rs3773679 (uncorrected p=0.009; corrected p=0.045) with remission when applying a recessive model of inheritance. The rs3732790T allele conferring a more favourable treatment response was furthermore found to be associated with stronger striatal responsiveness to happy facial expressions (sample 1: cluster-corrected p=0.002; sample 2: p=0.023). In summary, the present study suggests some impact of DRD3 gene variation on ECT response, potentially mediated by alteration of striatal engagement during the processing of emotionally rewarding stimuli.

Clinical and molecular genetics of psychotic depression

This review provides a comprehensive overview of clinical and molecular genetic as well as pharmacogenetic studies regarding the clinical phenotype of "psychotic depression." Results are discussed with regard to the long-standing debate on categorical vs dimensional disease models of affective and psychotic disorders on a continuum from unipolar depression over bipolar disorder and schizoaffective disorder to schizophrenia. Clinical genetic studies suggest a familial aggregation and a considerable heritability (39%) of psychotic depression partly shared with schizoaffective disorder, schizophrenia, and affective disorders. Molecular genetic studies point to potential risk loci of psychotic depression shared with schizoaffective disorder (1q42, 22q11, 19p13), depression, bipolar disorder, and schizophrenia (6p, 8p22, 10p13-12, 10p14, 13q13-14, 13q32, 18p, 22q11-13) and several vulnerability genes possibly contributing to an increased risk of psychotic symptoms in depression (eg, BDNF, DBH, DTNBP1, DRD2, DRD4, GSK-3beta, MAO-A). Pharmacogenetic studies implicate 5-HTT, TPH1, and DTNBP1 gene variation in the mediation of antidepressant treatment response in psychotic depression. Genetic factors are suggested to contribute to the disease risk of psychotic depression in partial overlap with disorders along the affective-psychotic spectrum. Thus, genetic research focusing on psychotic depression might inspire a more dimensional, neurobiologically and symptom-oriented taxonomy of affective and psychotic disorders challenging the dichotomous Kraepelinian view. Additionally, pharmacogenetic studies might aid in the development of a more personalized treatment of psychotic depression with an individually tailored antidepressive/antipsychotic pharmacotherapy according to genotype.

The role of single nucleotide polymorphism of D2 dopamine receptor gene on major depressive disorder and response to antidepressant treatment

The study analyzed the effect of dopamine 2 receptor gene (DRD2) polymorphism on the risk for major depressive disorder (MDD) and the response to selective serotonin reuptake inhibitors (SSRIs). The results suggest that the DRD2 gene may play a role on MDD susceptibility and the onset-time of antidepressant response.

The neurobiology of depression and antidepressant action

We present a comprehensive overview of the neurobiology of unipolar major depression and antidepressant drug action, integrating data from affective neuroscience, neuro- and psychopharmacology, neuroendocrinology, neuroanatomy, and molecular biology. We suggest that the problem of depression comprises three sub-problems: first episodes in people with low vulnerability ('simple' depressions), which are strongly stress-dependent; an increase in vulnerability and autonomy from stress that develops over episodes of depression (kindling); and factors that confer vulnerability to a first episode (a depressive diathesis). We describe key processes in the onset of a 'simple' depression and show that kindling and depressive diatheses reproduce many of the neurobiological features of depression. We also review the neurobiological mechanisms of antidepressant drug action, and show that resistance to antidepressant treatment is associated with genetic and other factors that are largely similar to those implicated in vulnerability to depression. We discuss the implications of these conclusions for the understanding and treatment of depression, and make some strategic recommendations for future research.

Association of DRD2 gene polymorphisms with mood disorders: a meta-analysis

BACKGROUND

In the past few decades, a number of studies have investigated the association of dopamine D2 receptor (DRD2) gene polymorphisms with mood disorders, but the findings are not always consistent. The aim of our study was to assess the association between DRD2 gene polymorphisms and mood disorders by using a meta-analysis.

METHODS

Data were collected from the following electronic databases: PubMed, Elsevier Science Direct, Cochrane Library, Chinese Biomedical Literature Database, China National Knowledge Infrastructure, and Wanfang, with the last report up to June 2010. Meta-analysis was performed in a fixed/random effect model by using the software Review Manager 4.2.

RESULTS

We identified 19 separate studies using search, but only 14 separate studies (2157 cases and 3272 controls) were included in the current study. Meta-analysis was performed for three DRD2 gene polymorphisms (-141Cins/del, Ser311/Cys311, and TaqI A1). We performed meta-analysis in overall, Caucasian, and Asian populations. We also performed disease-specific meta-analysis in unipolar disorder and bipolar disorder. We found no association between DRD2 gene -141Cins/del polymorphism and mood disorders in overall and Caucasian populations (P>0.05). We also found no association between DRD2 gene Ser311/Cys311 polymorphism and mood disorders in overall, Caucasian, and Asian populations (P>0.05). An association of DRD2 gene TaqI A1 polymorphism with mood disorders was found in overall population, and the individuals with A1A1 genotype were more susceptible to mood disorders in comparison to those with A2A1 and A2A2 genotypes (OR=1.84, 95% CI=1.07-3.17, P=0.03).

LIMITATION

Meta-analysis is retrospective research that is subject to the methodological deficiencies of the included studies.

CONCLUSION

This meta-analysis suggests that mood disorders may be associated with DRD2 gene TaqI A1 polymorphism, but not -141Cins/del and Ser311/Cys311.

Role of COMT, 5-HT(1A) , and SERT genetic polymorphisms on antidepressant response to Transcranial Magnetic Stimulation

BACKGROUND

Transcranial Magnetic Stimulation (TMS) is an effective technique in the treatment of depression, specifically in drug-resistant patients. However, there is little data available on the influence of genetic variables on TMS response.

METHODS

We analyzed the role of three genetic polymorphisms that affected the antidepressant response: serotonin transporter promoter region (SERTPR) polymorphism, 5-HT(1A) serotonergic receptor promoter region polymorphism (rs6295), and the coding region of COMT gene polymorphism (rs4680). Ninety patients with a major depressive drug-resistant episode due to a Major Depressive Disorder or to a Bipolar Disorder were included in our study. Patients underwent high frequency TMS, focused on the left prefrontal cortex, for 2 weeks. At study completion, the response rate was 45.5%. Effects of gene polymorphisms on clinical improvement were analyzed with an analysis of variance with each gene (SERTPR, 5-HT(1A) , and COMT) as factors and the Hamilton Rating Scale for Depression variation from baseline to the end of the treatment as a dependent variable.

RESULTS

We found a significant model in which three factors were not significant (diagnosis, COMT, and SERTPR), whereas factor 5-HT(1A) showed a significant influence on the outcome, with patients with C/C genotype showing a greater improvement than G/G and C/G and no difference between G/G and C/G.

CONCLUSION

According to our data, 5-HT(1A) polymorphism may play a role in influencing TMS response. The effect of COMT and SERTPR did not reach statistical significance. The analysis of these and other candidate genes in larger samples could help explain genetic influence on TMS response.

The COMTval158met polymorphism is associated with symptom relief during exposure-based cognitive-behavioral treatment in panic disorder

BACKGROUND

Cognitive behavioral therapy (CBT) represents a learning process leading to symptom relief and resulting in long-term changes in behavior. CBT for panic disorder is based on exposure and exposure-based processes can be studied in the laboratory as extinction of experimentally acquired fear responses. We have recently demonstrated that the ability to extinguish learned fear responses is associated with a functional genetic polymorphism (COMTval158met) in the COMT gene and this study was aimed at transferring the experimental results on the COMTval158met polymorphism on extinction into a clinical setting.

METHODS

We tested a possible effect of the COMTval158met polymorphism on the efficacy of CBT, in particular exposure-based treatment modules, in a sample of 69 panic disorder patients.

RESULTS

We present evidence that panic patients with the COMTval158met met/met genotype may profit less from (exposure-based) CBT treatment methods as compared to patients carrying at least one val-allele. No association was found with the 5-HTTLPR/rs25531 genotypes which is presented as additional material.

CONCLUSIONS

We were thus able to transfer findings on the effect of the COMTval158met polymorphism from an experimental extinction study obtained using healthy subjects to a clinical setting. Furthermore patients carrying a COMT val-allele tend to report more anxiety and more depression symptoms as compared to those with the met/met genotype. Limitations of the study as well as possible clinical implications are discussed.

TRIAL REGISTRATION

Clinical Trial Registry name: Internet-Versus Group-Administered Cognitive Behavior Therapy for Panic Disorder (IP2). Registration Identification number: NCT00845260, http://www.clinicaltrials.gov/ct2/show/NCT00845260.

COMT Val158Met genotype does not alter cortical or striatal dopamine D2 receptor availability in vivo

PURPOSE

Catechol-O-methyl transferase (COMT) is a pivotal regulator of brain dopamine function with a region-specific role. COMT is important in dopamine elimination in the prefrontal cortex, whereas dopamine reuptake is the main mechanism for synaptic removal of dopamine in the striatum. We studied whether the functional COMT gene polymorphism (Val158Met) associates with altered dopamine D2 receptor binding characteristics in vivo hypothesizing an effect in the cortex but not in the striatum.

PROCEDURES

Samples of 38 and 45 Finnish healthy subjects scanned previously with PET and the D2/D3 receptor radioligands [(11)C]FLB457 or [(11)C]raclopride, respectively, were genotyped for the Val158Met polymorphism.

RESULTS

No significant associations were found between the Val158Met genotype and D2 receptor binding characteristics in the cortex or the striatum as measured with [(11)C]FLB457 and [(11)C]raclopride, respectively.

CONCLUSIONS

COMT genotype is not related with alterations in baseline D2 receptor availability in vivo in the cortex or the striatum. This information is useful for the interpretation of genetic studies on COMT in neuropsychiatry.

Antidepressant electroconvulsive therapy: mechanism of action, recent advances and limitations

A considerable number of depressive patients do not respond to or remit during pharmacotherapeutical or psychotherapeutical interventions resulting in an increasing interest in non-pharmacological strategies to treat affective disorders. Electroconvulsive therapy (ECT) dates back to the beginning of modern biologic psychiatry and ongoing research has successfully improved efficacy in addition to safety while reducing side effects. Double-blind, randomized, controlled trials have shown powerful interactions between electrode placement (right unilateral, bifrontal, bitemporal) and dosage (relative to seizure threshold) in the efficacy and side effects of ECT. This review aims to summarize current research data on the mechanism of action, efficacy, and recent advances in ECT technique.