Association of the functional V158M catechol-O-methyl-transferase polymorphism with panic disorder in women

Hypnotherapy for agoraphobia-Feasibility and efficacy investigated in a pilot study

A number of case studies describing hypnotherapy in the treatment of anxiety disorder patients have already been published. Only a few randomized controlled trials (RCTs) investigated the efficacy of hypnotherapy but focused mainly on symptoms rather than specific mental disorders. The goal of this study was to investigate whether hypnotherapy (HT) was superior to a waitlist control group (WL) in the reduction of agoraphobia-related symptoms. Further goals were to report the feasibility of hypnotherapy as well as attrition and completion rates and detect (epi-)genetic variables, which might play a role in treatment outcome. This pilot study was based on a monocentric two-armed randomized controlled rater-blind clinical trial that was conducted between 2018 and 2020 with a waitlist control group. A total of 36 patients diagnosed with agoraphobia were randomized to either HT or WL. Patients in HT received individual outpatient treatment with hypnotherapy with 8 to 12 sessions for a period of 3 months. Patients in WL received HT after 3 months. Agoraphobia-related symptoms were assessed at baseline, after the treatment, and 3 months later in both groups with a clinician rating. The primary hypothesis concerning the difference between groups in the individual percentage symptom reduction could be confirmed in the intention-to-treat, not the per-protocol sample. Additionally, we applied repeated-measures analyses of variance and found a higher symptom decrease in HT compared with WL patients in three of the five imputed datasets. The dropout rate was low, and satisfaction with the treatment was high. HT patients experienced a strong symptom reduction after receiving hypnotherapy. WL patients improved slightly during the waiting period. The COMT Val108/158Met genotype had an effect on the agoraphobia-related symptoms as well as on COMT DNA methylation levels. This is the first study to indicate that hypnotherapy performed better than a waitlist control group regarding the reduction in anxiety symptoms in an RCT. Future studies should confirm the efficacy of hypnotherapy and compare the treatment with a standard treatment for anxiety disorders in a larger trial. Future studies should also investigate whether hypnotic susceptibility is associated with COMT Val108/158Met genotype and could predict treatment success for HT.

Clinical trial registration

https://classic.clinicaltrials.gov/ct2/show/NCT03684577, identifier: NCT03684577.

Positron Emission Tomography (PET) Imaging Tracers for Serotonin Receptors

Serotonin (5-hydroxytryptamine, 5-HT) and 5-HT receptors (5-HTRs) have crucial roles in various neuropsychiatric disorders and neurodegenerative diseases, making them attractive diagnostic and therapeutic targets. Positron emission tomography (PET) is a noninvasive nuclear molecular imaging technique and is an essential tool in clinical diagnosis and drug discovery. In this context, numerous PET ligands have been developed for "visualizing" 5-HTRs in the brain and translated into human use to study disease mechanisms and/or support drug development. Herein, we present a comprehensive repertoire of 5-HTR PET ligands by focusing on their chemotypes and performance in PET imaging studies. Furthermore, this Perspective summarizes recent 5-HTR-focused drug discovery, including biased agonists and allosteric modulators, which would stimulate the development of more potent and subtype-selective 5-HTR PET ligands and thus further our understanding of 5-HTR biology.

Catechol-O-methyltransferase activity does not influence emotional processing in men

BACKGROUND

Catechol-O-methyltransferase (COMT) regulates cortical dopaminergic transmission and prefrontal-dependent cognitive function. However, its role in other cognitive processes, including emotional processing, is relatively unexplored. We therefore investigated the separate and interactive influences of COMT inhibition and Val¹⁵⁸Met (rs4680) genotype on performance on an emotional test battery.

METHODS

We recruited 74 healthy men homozygous for the functional COMT Val¹⁵⁸Met polymorphism. Volunteers were administered either a single 200 mg dose of the brain-penetrant COMT inhibitor tolcapone or placebo in a double-blind, randomised manner. Emotional processing was assessed using the emotional test battery, and mood was rated using visual analogue scales and the Profile of Mood States (POMS) questionnaire across the test day.

RESULTS

There were no main or interactive effects of Val¹⁵⁸Met genotype or tolcapone on any of the emotional processing measures or mood ratings.

CONCLUSIONS

Our findings suggest that, at least in healthy adult men, COMT has little or no effect on emotional processing or mood. These findings contrast with several neuroimaging studies that suggest that COMT modulates neural activity during emotional processing. Thus, further studies are required to understand how COMT impacts on the relationship between behavioural output and neural activity during emotional processing. Nevertheless, our data suggest that novel COMT inhibitors under development for treating cognitive dysfunction are unlikely to have acute off target effects on emotional behaviours.

Investigating interactive effects of worry and the catechol-o-methyltransferase gene (COMT) on working memory performance

Extant research indicates that worry is associated with reduced working memory. It remains unclear, however, what mechanisms contribute to impaired performance in worriers. Critically, dopamine in the prefrontal cortex heavily influences the stability of mental representations during working memory tasks, yet no research has probed its role in associations between worry and working memory. To address this gap, the current study was designed to examine the moderating role of dopamine on the association between worry and working memory, using the catechol-o-methyltransferase (COMT) gene as a proxy for basal levels of dopamine. Across four assessments, we examined within- and between-person variation in worry and its interactive effects with COMT to predict working memory performance. Within-person variation in worry interacted with COMT to predict accuracy, such that higher worry across time predicted less accuracy for homozygous Val carriers but not Met carriers. Our findings demonstrate that basal dopamine plays an important role in how increases in worry across time for an individual negatively impact working memory performance.

Genetic Biomarkers of Panic Disorder: A Systematic Review

(1) Background: Although panic disorder (PD) is one of the most common anxiety disorders severely impacting quality of life, no effective genetic testing exists; known data on possible genetic biomarkers is often scattered and unsystematic which complicates further studies. (2) Methods: We used PathwayStudio 12.3 (Elsevier, The Netherlands) to acquire literature data for further manual review and analysis. 229 articles were extracted, 55 articles reporting associations, and 32 articles reporting no associations were finally selected. (3) Results: We provide exhaustive information on genetic biomarkers associated with PD known in the scientific literature. Data is presented in two tables. Genes COMT and SLC6A4 may be considered the most promising for PD diagnostic to date. (4) Conclusions: This review illustrates current progress in association studies of PD and may indicate possible molecular mechanisms of its pathogenesis. This is a possible basis for data analysis, novel experimental studies, or developing test systems and personalized treatment approaches.

The neurobiological basis of sex differences in learned fear and its inhibition

Learning that certain cues or environments predict threat enhances survival by promoting appropriate fear and the resulting defensive responses. Adapting to changing stimulus contingencies by learning that such cues no longer predict threat, or distinguishing between these threat-related and other innocuous stimuli, also enhances survival by limiting fear responding in an appropriate manner to conserve resources. Importantly, a failure to inhibit fear in response to harmless stimuli is a feature of certain anxiety and trauma-related disorders, which are also associated with dysfunction of the neural circuitry underlying learned fear and its inhibition. Interestingly, these disorders are up to twice as common in women, compared to men. Despite this striking sex difference in disease prevalence, the neurobiological factors involved remain poorly understood. This is due in part to the majority of relevant preclinical studies having neglected to include female subjects alongside males, which has greatly hindered progress in this field. However, more recent studies have begun to redress this imbalance and emerging evidence indicates that there are significant sex differences in the inhibition of learned fear and associated neural circuit function. This paper provides a narrative review on sex differences in learned fear and its inhibition through extinction and discrimination, along with the key gonadal hormone and brain mechanisms involved. Understanding the endocrine and neural basis of sex differences in learned fear inhibition may lead to novel insights on the neurobiological mechanisms underlying the enhanced vulnerability to develop anxiety-related disorders that are observed in women.

Genetics of sex differences in neuroanatomy and function

Sex differences are observed at many distinct biologic levels, such as in the anatomy and functioning of the brain, behavior, and susceptibility to neuropsychiatric disorders. Previously, these differences were believed to entirely result from the secretion of gonadal hormones; however, recent research has demonstrated that differences are also the consequence of direct or nonhormonal effects of genes located on the sex chromosomes. This chapter reviews the four core genotype model that separates the effects of hormones and sex chromosomes and highlights a few genes that are believed to be partly responsible for sex dimorphism of the brain, in particular, the Sry gene. Genetics of the brain's neurochemistry is discussed and the susceptibility to certain neurologic and psychiatric disorders is reviewed. Lastly, we discuss the sex-specific genetic contribution in disorders of sexual development. The precise molecular mechanisms underlying these differences are currently not entirely known. An increased knowledge and understanding of the role of candidate genes will undeniably be of great aid in elucidating the molecular basis of sex-biased disorders and potentially allow for more sex-specific therapies.

rs2572431 Polymorphism on Chromosome 8 Is Associated With Individual Differences in Anxiety Related Coping Modes

OBJECTIVE

The role of genetic factors in the interplay between anxiety-related coping and personality has been the subject of interest in numerous previous studies. The current study focused on anxiety-related coping modes, namely repression versus sensitization (i.e., cognitive avoidance versus vigilance), and the single nucleotide polymorphism (SNP) rs2572431. An association between this SNP and anxiety-related personality traits has previously been shown in a genome wide association study, thus further investigation of the relationship between this SNP and anxiety-related coping seems warranted.

METHODS

In the present study, N = 880 mostly Caucasian participants (n = 269 males and n = 611 females; mean-age: 23.88, SD = 7.19) filled in a personality questionnaire assessing individual differences in cognitive avoidance and vigilance, and all participants were genotyped for rs2572431.

RESULTS

Participants homozygous for the T-allele in rs2572431 showed the highest vigilance scores in all scenarios tested. This is in line with findings from an earlier genome wide association study demonstrating that the T-allele is also associated with higher neuroticism scores.

CONCLUSION

The current study yields evidence for the role of rs2572431 in the molecular genetic underpinnings of coping modes and, more broadly, for its connection with personality.

Heterosis in COMT Val158Met Polymorphism Contributes to Sex-Differences in Children's Math Anxiety

Math anxiety (MA) is a phobic reaction to math activities, potentially impairing math achievement. Higher frequency of MA in females is explainable by the interaction between genetic and environmental factors. The molecular-genetic basis of MA has not been investigated. The COMT Val158Met polymorphism, which affects dopamine levels in the prefrontal cortex, has been associated with anxiety manifestations. The valine allele is associated with lower, and the methionine allele with higher, dopamine availability. In the present study, the effects of sex and COMT Val158Met genotypes on MA were investigated: 389 school children aged 7-12 years were assessed for intelligence, numerical estimation, arithmetic achievement and MA and genotyped for COMT Val158Met polymorphism. The Math Anxiety Questionnaire (MAQ) was used to assess the cognitive and affective components of MA. All genotype groups of boys and girls were comparable regarding genotype frequency, age, school grade, numerical estimation, and arithmetic abilities. We compared the results of all possible genetic models: codominance (Val/Val vs. Val/Met vs. Met/Met), heterosis (Val/Met vs. Val/Val plus Met/Met), valine dominance (Val/Val plus Val/Met vs. Met/Met), and methionine dominance (Met/Met plus Val/Met vs. Val/Val). Models were compared using AIC and AIC weights. No significant differences between girls and boys and no effects of the COMT Val158Met polymorphism on numerical estimation and arithmetic achievement were observed. Sex by genotype effects were significant for intelligence and MA. Intelligence scores were higher in Met/Met girls than in girls with at least one valine allele (valine dominance model). The best fitting model for MA was heterosis. In Anxiety Toward Mathematics, heterozygous individuals presented MA levels close to the grand average regardless of sex. Homozygous boys were significantly less and homozygous girls significantly more math anxious. Heterosis has been seldom explored, but in recent years has emerged as the best genetic model for some phenotypes associated with the COMT Val158Met polymorphism. This is the first study to investigate the genetic-molecular basis of MA.

Association of rs4680 COMT, rs6280 DRD3, and rs7322347 5HT2A With Clinical Features of Youth-Onset Schizophrenia

We investigated the associations of rs4680 COMT, rs6280 DRD3, and rs7322347 5HT2A with youth-onset schizophrenia in the Russian population in a case-control study, and the role of the genotype in the severity of clinical features. The association between rs7322347 and schizophrenia (p = 0.0001) is described for the first time. Furthermore, we found a link with rs6280 and rs4680 in females (p = 0.001 and p = 0.02 respectively) and with rs7322347 in males (p = 0.002). Clinical symptoms were assessed on three scales: the Clinician-Rated Dimensions of Psychosis Symptom Severity scale, Positive and Negative Syndrome Scale, and Frontal Assessment Battery. Gender differences in clinical features are of particular interest. In our study we found gender differences in the severity of clinical features-higher scores for delusions (Positive and Negative Syndrome Scale and Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition) in males and higher scores for depression, delusions, somatic concern, motor retardation, poor attention were found in females.

Haplotypic and Genotypic Association of Catechol-O-Methyltransferase rs4680 and rs4818 Polymorphisms and Treatment Resistance in Schizophrenia

Treatment-resistant schizophrenia (TRS) continues to be a challenge. It was related to different factors, including alterations in the activity of brain dopaminergic system, which could be influenced by the dopamine-degrading enzyme, catechol-O-methyltransferase (COMT). Variants of the COMT gene have been extensively studied as risk factors for schizophrenia; however, their association with TRS has been poorly investigated. The aim of the present study was to determine the haplotypic and genotypic association of COMT rs4680 and rs4818 polymorphisms with the presence of TRS. Overall, 931 Caucasian patients diagnosed with schizophrenia (386 females and 545 males) were included, while 270 participants met the criteria for TRS. In males, no significant haplotypic and genotypic associations between COMT rs4680 and rs4818 polymorphisms and TRS were detected. However, genotypic analyses demonstrated higher frequency of COMT rs4680 AA genotype carriers compared to G-allele carriers (p = 0.033) and higher frequency of COMT rs4818 CC genotype carriers than G-allele carriers (p = 0.014) in females with TRS. Haplotype analyses confirmed that the presence of the G allele in females was associated with lower risk of TRS. In women with TRS, the high activity G-G/G-G haplotype was rare, while carriers of other haplotypes were overrepresented (p = 0.009). Such associations of COMT rs4680 and rs4818 high-activity (G variants), as well as G-G/G-G haplotype, with the lower risk of TRS in females, but not in males, suggest significant, but sex-specific influence of COMT variants on the development of treatment-resistance in patients with schizophrenia. However, due to relatively low number of females, those findings require replication in a larger sample.

Interplay between COMT Val158Met, childhood adversities and sex in predicting panic pathology: Findings from a general population sample

BACKGROUND

The single nucleotide polymorphism rs4680 of the catechol-O-methyltransferase (COMT) gene has been implicated to be involved in the etiopathogenesis of panic. However, it remains unresolved whether rs4680 modifies the risk-association between early life stress and subsequent development of panic pathology.

METHODS

The genotype of rs4680 was determined for n = 2242 adults with European ancestry from the Study of Health in Pomerania (SHIP, a regional longitudinal cohort study from northeastern Germany). Lifetime fearful spells, panic attacks and panic disorder were assessed according to DSM-IV in 2007-2010 (when participants were aged 29-89) using the Munich Composite International Diagnostic Interview (DIA-X/M-CIDI). Childhood adversities were assessed with the Childhood Trauma Questionnaire (CTQ).

RESULTS

Logistic regressions with interaction terms (adjusted for sex and age) revealed that rs4680 interacted with total childhood adversity, emotional abuse and physical abuse in predicting panic disorder: Respective childhood adversities predicted panic disorder in carriers of the Val/Met or Met/Met genotype, but not Val/Val genotype. Moreover, a 3-way interaction was found between rs4680, emotional abuse and sex in predicting panic attacks: Emotional abuse predicted panic attacks among male carriers of the Val/Val genotype and female carriers of the Val/Met or Met/Met genotype, but not among male carriers of the Val/Met or Met/Met genotype or female carriers of the Val/Val genotype.

LIMITATIONS

Genotype data were derived by imputation. Childhood adversities and panic were assessed retrospectively.

CONCLUSIONS

Especially (female) carriers of the Val/Met or Met/Met genotype of rs4680 might profit from targeted early interventions to prevent the onset of panic after childhood adversities.

The COMT-polymorphism is not associated with the incidence of acute kidney injury after cardiac surgery - a prospective cohort study

Background

The Catechol-O-methyltransferase (COMT) represents the key enzyme in catecholamine degradation. Recent studies suggest that the COMT rs4680 polymorphism is associated with the response to endogenous and exogenous catecholamines. There are, however, conflicting data regarding the COMT Met/Met phenotype being associated with an increased risk of acute kidney injury (AKI) after cardiac surgery. The aim of the current study is to prospectively investigate the impact of the COMT rs4680 polymorphism on the incidence of AKI in patients undergoing cardiac surgery.

Methods

In this prospective single center cohort study consecutive patients hospitalized for elective cardiac surgery including cardiopulmonary-bypass (CPB) were screened for participation. Demographic clinical data, blood, urine and tissue samples were collected at predefined time points throughout the clinical stay. AKI was defined according to recent recommendations of the Kidney Disease Improving Global Outcome (KDIGO) group. Genetic analysis was performed after patient enrolment was completed.

Results

Between April and December 2014, 150 patients were recruited. The COMT genotypes were distributed as follows: Val/Met 48.7%, Met/Met 29.3%, Val/Val 21.3%. No significant differences were found for demography, comorbidities, or operative strategy according to the underlying COMT genotype. AKI occurred in 35 patients (23.5%) of the total cohort, and no differences were evident between the COMT genotypes (20.5% Met/Met, 24.7% Val/Met, 25.0% Val/Val, p = 0.66). There were also no differences in the post-operative period, including ICU or in-hospital stay.

Conclusions

We did not find statistically significant variations in the risk for postoperative AKI, length of ICU or in-hospital stay according to the underlying COMT genotype.

Catechol-O-methyltransferase Val158Met polymorphism associates with affect and cortisol levels in women

Introduction

We tested the extent to which the catechol-O-methyltransferase (COMT) Val158Met polymorphism is associated with affective state and evening cortisol levels. We limited our study to women as previous research suggests that the link between COMT genotype and psychological health is entangled by sex differences.

Materials and Methods

The participants were assessed on measures of anxiety, mood disturbance, depressive symptomatology, and perceived stress. We also evaluated participants on a quality of life measures that included two emotion domains and two physical domains (physical health and environment).

Results

We found that under normal (nonstress) conditions, the COMT A allele (Met carriers, higher dopamine) associates with healthier affect and lower afternoon cortisol levels in women. These effects were limited to affective measures and not to physical or environmental quality of life.

Conclusions

These findings help to shed light on the complex nature of COMT and emotion, and suggest that both sex and task condition (stress vs. nonstress) should be considered when examining the relationship between COMT genotype and emotion.

Mobilization of Peripheral Blood Stem Cells and Changes in the Concentration of Plasma Factors Influencing their Movement in Patients with Panic Disorder

In this paper we examined whether stem cells and factors responsible for their movement may serve as new biological markers of anxiety disorders. The study was carried out on a group of 30 patients diagnosed with panic disorder (examined before and after treatment), compared to 30 healthy individuals forming the control group. We examined the number of circulating HSCs (hematopoetic stem cells) (Lin−/CD45 +/CD34 +) and HSCs (Lin−/CD45 +/AC133 +), the number of circulating VSELs (very small embryonic-like stem cells) (Lin−/CD45−/CD34 +) and VSELs (Lin−/CD45−/AC133 +), as well as the concentration of complement components: C3a, C5a and C5b-9, SDF-1 (stromal derived factor) and S1P (sphingosine-1-phosphate). Significantly lower levels of HSCs (Lin−/CD45 +/AC133 +) have been demonstrated in the patient group compared to the control group both before and after treatment. The level of VSELs (Lin−/CD45−/CD133 +) was significantly lower in the patient group before treatment as compared to the patient group after treatment.

The levels of factors responsible for stem cell movement were significantly lower in the patient group compared to the control group before and after treatment. It was concluded that the study of stem cells and factors associated with their movement can be useful in the diagnostics of panic disorder, as well as differentiating between psychotic and anxiety disorders.

GLRB allelic variation associated with agoraphobic cognitions, increased startle response and fear network activation: a potential neurogenetic pathway to panic disorder

The molecular genetics of panic disorder (PD) with and without agoraphobia (AG) are still largely unknown and progress is hampered by small sample sizes. We therefore performed a genome-wide association study with a dimensional, PD/AG-related anxiety phenotype based on the Agoraphobia Cognition Questionnaire (ACQ) in a sample of 1370 healthy German volunteers of the CRC TRR58 MEGA study wave 1. A genome-wide significant association was found between ACQ and single non-coding nucleotide variants of the GLRB gene (rs78726293, P=3.3 × 10^-8; rs191260602, P=3.9 × 10^-8). We followed up on this finding in a larger dimensional ACQ sample (N=2547) and in independent samples with a dichotomous AG phenotype based on the Symptoms Checklist (SCL-90; N=3845) and a case-control sample with the categorical phenotype PD/AG (N_combined =1012) obtaining highly significant P-values also for GLRB single-nucleotide variants rs17035816 (P=3.8 × 10^-4) and rs7688285 (P=7.6 × 10^-5). GLRB gene expression was found to be modulated by rs7688285 in brain tissue, as well as cell culture. Analyses of intermediate PD/AG phenotypes demonstrated increased startle reflex and increased fear network, as well as general sensory activation by GLRB risk gene variants rs78726293, rs191260602, rs17035816 and rs7688285. Partial Glrb knockout mice demonstrated an agoraphobic phenotype. In conjunction with the clinical observation that rare coding GLRB gene mutations are associated with the neurological disorder hyperekplexia characterized by a generalized startle reaction and agoraphobic behavior, our data provide evidence that non-coding, although functional GLRB gene polymorphisms may predispose to PD by increasing startle response and agoraphobic cognitions.

Genetic Polymorphism of 1019C/G (rs6295) Promoter of Serotonin 1A Receptor and Catechol-O-Methyltransferase in Panic Disorder

OBJECTIVE

Family and twin studies have suggested genetic liability for panic disorder (PD) and therefore we sought to determine the role of noradrenergic and serotonergic candidate genes for susceptibility for PD in a Japanese population.

METHODS

In this age- and gender-matched case-control study involving 119 PD patients and 119 healthy controls, we examined the genotype distributions and allele frequencies of the serotonin transporter gene linked polymorphic region (5-HTTLPR), -1019C/G (rs6295) promoter polymorphism of the serotonin receptor 1A (5-HT1A), and catechol-O-methyltransferase (COMT) gene polymorphism (rs4680) and their association with PD.

RESULTS

No significant differences were evident in the allele frequencies or genotype distributions of the COMT (rs4680), 5-HTTLPR polymorphisms or the -1019C/G (rs6295) promoter polymorphism of 5-HT1A between PD patients and controls. Although there were no significant associations of these polymorphisms with in subgroups of PD patients differentiated by gender or in subgroup comorbid with agoraphobia (AP), significant difference was observed in genotype distributions of the -1019C/G (rs6295) promoter polymorphism of 5-HT1A between PD patients without AP and controls (p=0.047).

CONCLUSION

In this association study, the 1019C/G (rs6295) promoter polymorphism of the 5-HT1A receptor G/G genotype was associated with PD without AP in a Japanese population.

Biological markers for anxiety disorders, OCD and PTSD - a consensus statement. Part I: Neuroimaging and genetics

OBJECTIVES

Biomarkers are defined as anatomical, biochemical or physiological traits that are specific to certain disorders or syndromes. The objective of this paper is to summarise the current knowledge of biomarkers for anxiety disorders, obsessive-compulsive disorder (OCD) and post-traumatic stress disorder (PTSD).

METHODS

Findings in biomarker research were reviewed by a task force of international experts in the field, consisting of members of the World Federation of Societies for Biological Psychiatry Task Force on Biological Markers and of the European College of Neuropsychopharmacology Anxiety Disorders Research Network.

RESULTS

The present article (Part I) summarises findings on potential biomarkers in neuroimaging studies, including structural brain morphology, functional magnetic resonance imaging and techniques for measuring metabolic changes, including positron emission tomography and others. Furthermore, this review reports on the clinical and molecular genetic findings of family, twin, linkage, association and genome-wide association studies. Part II of the review focuses on neurochemistry, neurophysiology and neurocognition.

CONCLUSIONS

Although at present, none of the putative biomarkers is sufficient and specific as a diagnostic tool, an abundance of high-quality research has accumulated that will improve our understanding of the neurobiological causes of anxiety disorders, OCD and PTSD.

Candidate genes in panic disorder: meta-analyses of 23 common variants in major anxiogenic pathways

The utilization of molecular genetics approaches in examination of panic disorder (PD) has implicated several variants as potential susceptibility factors for panicogenesis. However, the identification of robust PD susceptibility genes has been complicated by phenotypic diversity, underpowered association studies and ancestry-specific effects. In the present study, we performed a succinct review of case-control association studies published prior to April 2015. Meta-analyses were performed for candidate gene variants examined in at least three studies using the Cochrane Mantel-Haenszel fixed-effect model. Secondary analyses were also performed to assess the influences of sex, agoraphobia co-morbidity and ancestry-specific effects on panicogenesis. Meta-analyses were performed on 23 variants in 20 PD candidate genes. Significant associations after correction for multiple testing were observed for three variants, TMEM132D rs7370927 (T allele: odds ratio (OR)=1.27, 95% confidence interval (CI): 1.15-1.40, P=2.49 × 10(-6)), rs11060369 (CC genotype: OR=0.65, 95% CI: 0.53-0.79, P=1.81 × 10(-5)) and COMT rs4680 (Val (G) allele: OR=1.27, 95% CI: 1.14-1.42, P=2.49 × 10(-5)) in studies with samples of European ancestry. Nominal associations that did not survive correction for multiple testing were observed for NPSR1 rs324891 (T allele: OR=1.22, 95% CI: 1.07-1.38, P=0.002), TPH1 rs1800532 (AA genotype: OR=1.46, 95% CI: 1.14-1.89, P=0.003) and HTR2A rs6313 (T allele: OR=1.19, 95% CI: 1.07-1.33, P=0.002) in studies with samples of European ancestry and for MAOA-uVNTR in female PD (low-active alleles: OR=1.21, 95% CI: 1.07-1.38, P=0.004). No significant associations were observed in the secondary analyses considering sex, agoraphobia co-morbidity and studies with samples of Asian ancestry. Although these findings highlight a few associations, PD likely involves genetic variation in a multitude of biological pathways that is diverse among populations. Future studies must incorporate larger sample sizes and genome-wide approaches to further quantify the observed genetic variation among populations and subphenotypes of PD.

Genetics of anxiety: would the genome recognize the DSM?

The nosology of anxiety disorders has undergone substantial evolution over the past several decades. The modern classification of these disorders dates to the publication of Diagnostic and Statistical Manual-III (DSM-III) in 1980, but the validity of the current diagnostic categories has been the subject of controversy. Genetic research can help clarify the boundaries of diagnostic categories by examining the etiologic relationships among them. The question posed in the title of this article asks to what degree the DSM-IV definitions of the anxiety disorders are supported by the evolving body of research on the genetic basis of pathologic anxiety. With DSM-V on the horizon, there is a renewed imperative to examine the structure of these disorders. In this article, we address this issue by, first, providing a brief update about the current status of genetic research on anxiety disorders and then considering whether the evidence suggests that genetic influences conform to or transcend DSM definitions. Finally, we discuss future directions for the genetic dissection of anxiety disorders.

Serotonin pathway polymorphisms and the treatment of major depressive disorder and anxiety disorders

While antidepressants are widely used to treat major depressive disorder and anxiety disorders, only half of the patients will respond to antidepressant treatment and only a third of patients will experience a remission of symptoms. Identification of genetic biomarkers that predict antidepressant treatment response could thus greatly improve current clinical practice by providing guidance on which drug to use for which patient. Most antidepressant drugs for the treatment of depression and anxiety disorders have effects on the serotonergic neurotransmitter system; thus, genetic polymorphisms in the genes involved in this pathway represent logical candidates for investigation. This article reviews recent findings on the pharmacogenetics of antidepressant drugs with a focus on serotonergic pathway polymorphisms and discusses future clinical applications.

Sex differences in the locus coeruleus-norepinephrine system and its regulation by stress

Women are more likely than men to suffer from post-traumatic stress disorder (PTSD) and major depression. In addition to their sex bias, these disorders share stress as an etiological factor and hyperarousal as a symptom. Thus, sex differences in brain arousal systems and their regulation by stress could help explain increased vulnerability to these disorders in women. Here we review preclinical studies that have identified sex differences in the locus coeruleus (LC)-norepinephrine (NE) arousal system. First, we detail how structural sex differences in the LC can bias females towards increased arousal in response to emotional events. Second, we highlight studies demonstrating that estrogen can increase NE in LC target regions by enhancing the capacity for NE synthesis, while reducing NE degradation, potentially increasing arousal in females. Third, we review data revealing how sex differences in the stress receptor, corticotropin releasing factor 1 (CRF1), can increase LC neuronal sensitivity to CRF in females compared to males. This effect could translate into hyperarousal in women under conditions of CRF hypersecretion that occur in PTSD and depression. The implications of these sex differences for the treatment of stress-related psychiatric disorders are discussed. Moreover, the value of using information regarding biological sex differences to aid in the development of novel pharmacotherapies to better treat men and women with PTSD and depression is also highlighted. This article is part of a Special Issue entitled SI: Noradrenergic System.

Multilevel impact of the dopamine system on the emotion-potentiated startle reflex

RATIONALE/OBJECTIVES

The pathogenetic mechanism of emotion-related disorders such as anxiety disorders is considered to be complex with an interaction of genetic, biochemical, and environmental factors. Particular evidence has accumulated for alterations in the dopaminergic system-partly conferred by catechol-O-methyltransferase (COMT) gene variation-and for distorted emotional processing to constitute risk factors for anxiety and anxiety-related disorders.

METHODS

Applying a multilevel approach, we analyzed the main and interactive effects of the functional COMT val158met polymorphism and L-dopa (single-dose 50 mg levodopa and 12.5 mg carbidopa; double-blind, placebo-controlled design) on the emotion-potentiated (unpleasant, neutral, and pleasant IAPS pictures) startle response as an intermediate phenotype of anxiety in a sample of 100 healthy probands (f = 52, m = 48).

RESULTS

The COMT 158val allele was associated with an increased startle potentiation by unpleasant stimuli as compared with neutral stimuli irrespective of L-dopa or placebo intervention. COMT 158met/met genotype carriers, while displaying no difference in startle magnitude in response to unpleasant or neutral pictures in the placebo condition, showed startle potentiation by unpleasant pictures under L-dopa administration only.

CONCLUSIONS

The present proof-of-concept study provides preliminary support for a complex, multilevel impact of the dopaminergic system on the emotion-potentiated startle reflex suggesting increased phasic dopamine transmission driven by the more active COMT 158val allele and/or a single dose of L-dopa to predispose to maladaptive emotional processing and thereby potentially also to anxiety-related psychopathological states.

Immune-related pathways including HLA-DRB1(∗)13:02 are associated with panic disorder

Panic disorder (PD) is an anxiety disorder characterized by panic attacks and anticipatory anxiety. Both genetic and environmental factors are thought to trigger PD onset. Previously, we performed a genome-wide association study (GWAS) for PD and focused on candidate SNPs with the lowest P values. However, there seemed to be a number of polymorphisms which did not reach genome-wide significance threshold due to their low allele frequencies and odds ratios, even though they were truly involved in pathogenesis. Therefore we performed pathway analyses in order to overcome the limitations of conventional single-marker analysis and identify associated SNPs with modest effects. Each pathway analysis indicated that pathways related to immunity showed the strongest association with PD (DAVID, P=2.08×10(-6); i-GSEA4GWAS, P<10(-3); ICSNPathway, P<10(-3)). Based on the results of pathway analyses and the previously performed GWAS for PD, we focused on and investigated HLA-B and HLA-DRB1 as candidate susceptibility genes for PD. We typed HLA-B and HLA-DRB1 in 744 subjects with PD and 1418 control subjects. Patients with PD were significantly more likely to carry HLA-DRB1(∗)13:02 (P=2.50×10(-4), odds ratio=1.54). Our study provided initial evidence that HLA-DRB1(∗)13:02 and genes involved in immune-related pathways are associated with PD. Future studies are necessary to confirm these results and clarify the underlying mechanisms causing PD.

From neural to genetic substrates of panic disorder: Insights from human and mouse studies

Fear is an ancestral emotion, an intrinsic defensive response present in every organism. Although fear is an evolutionarily advantageous emotion, under certain pathologies such as panic disorder it might become exaggerated and non-adaptive. Clinical and preclinical work pinpoints that changes in cognitive processes, such as perception and interpretation of environmental stimuli that rely on brain regions responsible for high-level function, are essential for the development of fear-related disorders. This review focuses on the involvement of cognitive function to fear circuitry disorders. Moreover, we address how animal models are contributing to understand the involvement of human candidate genes to pathological fear and helping achieve progress in this field. Multidisciplinary approaches that integrate human genetic findings with state of the art genetic mouse models will allow to elucidate the mechanisms underlying pathology and to develop new strategies for therapeutic targeting.

Association of COMT and TPH-2 genes with DSM-5 based PTSD symptoms

BACKGROUND

Dopaminergic and serotonergic systems have been implicated in PTSD. The present study evaluated the association of four catechol-O-methyltransferase (COMT) gene loci, and the joint effect of COMT and tryptophan hydroxylase 2 (TPH2) genes on PTSD symptoms.

METHODS

Subjects included 200 Caucasian Armenian adults exposed to the 1988 Spitak earthquake from 12 multigenerational (3-5 generations) families. Instruments used included the UCLA PTSD Reaction Index based on DSM-5 criteria, and the Beck Depression Inventory.

RESULTS

The adjusted heritabilitiy of vulnerability to DSM-5 based PTSD symptoms was 0.60 (p<10(-4)). There was a significant association of the COMT allele rs4633C with total PTSD (p<0.03), and D category (p<0.04) (negative alterations in cognitions and mood) severity scores, but not with C category (avoidance) scores. There was no genetic correlation between C and D category severity scores. COMT allele rs4633C and the TPH-2 allele rs11178997T together accounted for 7% of the variance in PTSD severity scores (p<0.001). None of the COMT alleles were associated with depression.

LIMITATIONS

The ratings of earthquake exposure and prior trauma may have been subject to recall bias. The findings may not be generalizable to other ethnic/racial populations.

CONCLUSION

COMT allele rs4633C may be causally related and/or is in linkage disequilibrium with gene(s) that are causally related to PTSD symptoms. Carriers of these COMT and the TPH-2 alleles may be at increased risk for PTSD. The findings provide biological support for dividing DSM-IV category C symptoms into DSM-5 categories C and D.

Association of TMEM132D, COMT, and GABRA6 genotypes with cingulate, frontal cortex and hippocampal emotional processing in panic and major depressive disorder

OBJECTIVE

The aim of the study was to evaluate the association of transmembrane protein 132D (TMEM132D), catechol-O-methyltransferase (COMT), and gamma-aminobutyric acid (GABA) receptor alpha 6 subunit (GABRA6) genotypes with cingulate, frontal cortex and hippocampal emotional processing in panic disorder (PD) and major depressive disorder (MDD).

METHOD

The single nucleotide polymorphisms (SNPs) in TMEM132D, COMT, and GABRA6 were examined in patients with MDD, PD, and healthy controls. Functional magnetic resonance imaging (fMRI) was performed in patients with MDD, PD, and healthy controls.

RESULTS

rs4680 in COMT and rs3219151 in GABRA6 showed positive associations with PD and MDD. A dynamic fearful face was shown to the participants during fMRI scanning. In PD patients, responses in the bilateral anterior cingulate were stronger in carriers of the AA genotype of SNP rs11060369 in TMEM132D compared with carriers of the AC + CC genotype, and stronger in CT + TT genotype carriers of SNP rs3219151 in GABRA6 compared with carriers of the CC genotype. The response in the medial orbital frontal cortex was stronger in carriers of the CT + TT genotypes of SNP rs3219151 in PD. In MDD patients, the response in the right parahippocampus of carriers of the GG genotype of rs4680 in COMT was stronger than that of carriers of the AA + AG genotype.

CONCLUSION

These results suggest that TMEM132D, GABRA6, and COMT variants may increase vulnerability to panic.

Association of the catechol-O-methyltransferase val158met polymorphism and anxiety-related traits: a meta-analysis

OBJECTIVES

The aims of this study were (i) to examine genotypic association of the catechol-O-methyltransferase (COMT) val158met polymorphism with anxiety-related traits with a meta-analysis; (ii) to examine sex and ethnicity as moderators of the association; and (iii) to evaluate whether the association differed by particular anxiety traits.

METHODS

Association studies of the COMT val158met polymorphism and anxiety traits were identified from the PubMed or PsycInfo databases, conference abstracts, and listserv postings. Exclusion criteria were (a) pediatric samples, (b) exclusively clinical samples, and (c) samples selected for a nonanxiety phenotype. Standardized mean differences in anxiety between genotypes were aggregated to produce mean effect sizes across all available samples, and for subgroups stratified by sex and ethnicity (Whites vs. Asians). Construct-specific analysis was conducted to evaluate the association of COMT with neuroticism, harm avoidance, and behavioral inhibition.

RESULTS

Twenty-seven eligible studies (N=15 979) with available data were identified. Overall findings indicate sex-specific and ethnic-specific effects: valine homozygotes had higher neuroticism than methionine homozygotes in studies of White males [mean effect size(Equation is included in full-text article.)=0.13; 95% CI 0.02, 0.25; P=0.03], and higher harm avoidance in studies of Asian males ((Equation is included in full-text article.)=0.43; 95% CI 0.14, 0.72; P=0.004). No significant associations were found in women and effect sizes were diminished when studies were aggregated across ethnicity or anxiety traits.

CONCLUSION

This meta-analysis provides evidence for sex and ethnic differences in the association of the COMT val158met polymorphism with anxiety traits. Our findings contribute to current knowledge on the relation between prefrontal dopaminergic transmission and anxiety.

Gene×gene×gender interaction of BDNF and COMT genotypes associated with panic disorder

Genetic and gender differences are among the factors that have a role in the etiology of panic disorder (PD). It is thought that PD is related to neurotransmitter pathways, such as brain-derived neurotrophic factor (BDNF) and catechol-O-methyltransferase (COMT), both of which are involved in the regulation of the monoamine mechanism. We examined the interactions of BDNF, COMT and gender differences in terms of personality characteristics in PD. The subjects were 470 patients (178 men, 292 women) with a DSM-IV diagnosis of PD, and 458 healthy controls (195 men, 263 women). The subjects were further clinically characterized using the Revised NEO Personality Inventory (NEO-PI-R) and State-Trait Anxiety Inventory (STAI). COMT Val158Met polymorphisms (rs4680) and BDNF Val66Met (rs6265) polymorphisms were genotyped using allelic discrimination by a real-time PCR assay. A multivariate analysis of covariance (MANCOVA) was performed with STAI and NEO-PI-R scores as the dependent factor, gender and genotyping groups (BDNF and COMT) as fixed factors, and the covariate of age in the PD and healthy control groups. Post hoc MANCOVA tests were conducted to evaluate COMT × BDNF interactions. An interaction of BDNF × COMT × gender was confirmed in the PD group by MANCOVA on STAI scores and NEO-PI-R Neuroticism and Extraversion scores, whereas no association of such interactions was observed in the healthy controls. The anxiety sensitivity of the COMT Met+BDNF Val/Val carriers was higher than that of the COMT Val/Val+BDNF Val/Val carriers by post hoc MANCOVA. A significant BDNF × COMT × gender interaction was observed in the PD patients but not in the controls. Our findings partly demonstrated the involvement of a gene × gene × gender interaction in the pathogenesis of PD.

Acute anxiolytic effects of quetiapine during virtual reality exposure--a double-blind placebo-controlled trial in patients with specific phobia

Anxiety disorders are among the most frequent psychiatric disorders. With regard to pharmacological treatment, antidepressants, the calcium modulator pregabalin and benzodiazepines are recommended according to current treatment guidelines. With regard to acute states of anxiety, so far practically only benzodiazepines provide an immediate anxiolytic effect. However, the risk of tolerance and dependency limits the use of this class of medication. Therefore, there is still a need for alternative pharmacologic strategies. Increasing evidence points towards anxiety-reducing properties of atypical antipsychotics, particularly quetiapine. Therefore, we aimed to evaluate the putative acute anxiolytic effects of this compound, choosing the induction of acute anxiety in patients with specific phobia as a model for the evaluation of ad-hoc anxiolytic properties in a proof-of-concept approach. In a randomized, double-blind, placebo-controlled study, 58 patients with arachnophobia were treated with a single dose of quetiapine XR or placebo prior to a virtual reality spider challenge procedure. Treatment effects were monitored using rating scales for acute anxiety as well as measurements of heart rate and skin conductance. Overall, quetiapine showed significant anxiolytic effects compared to placebo. However, effects were not seen on the primary outcome measure (VAS Anxiety), but were limited to somatic anxiety symptoms. Additionally, a significant reduction of skin conductance was observed. Further exploratory analyses hint towards a mediating role of the (COMT) val158met genotype on treatment response. The present results thus suggest a possible suitability of quetiapine in the acute treatment of anxiety, particularly with regard to somatic symptoms.

Advances in the neuroimaging of panic disorder

Models of the neuroanatomy of panic disorder (PD) have relied on both animal work on fear and on clinical data from neuroimaging. Early work hypothesised a network of brain regions involved in fear processing (e.g. the amygdala), but more recent work has also pointed to the involvement of other cortical areas and other brain circuitry (e.g. the insula and anterior cingulate cortex). Studies investigating functional and structural brain connectivity in PD may ultimately shed light on the extent to which the neuroanatomy of PD is localised versus distributed, and on how current treatments alter this neuroanatomy.

The interaction of early life experiences with COMT val158met affects anxiety sensitivity

The pathogenesis of anxiety disorders is considered to be multifactorial with a complex interaction of genetic factors and individual environmental factors. Therefore, the aim of this study was to examine gene-by-environment interactions of the genes coding for catechol-O-methyltransferase (COMT) and monoamine oxidase A (MAOA) with life events on measures related to anxiety. A sample of healthy subjects (N = 782; thereof 531 women; mean age M = 24.79, SD = 6.02) was genotyped for COMT rs4680 and MAOA-uVNTR (upstream variable number of tandem repeats), and was assessed for childhood adversities [Childhood Trauma Questionnaire (CTQ)], anxiety sensitivity [Anxiety Sensitivity Index (ASI)] and anxious apprehension [Penn State Worry Questionnaire (PSWQ)]. Main and interaction effects of genotype, environment and gender on measures related to anxiety were assessed by means of regression analyses. Association analysis showed no main gene effect on either questionnaire score. A significant interactive effect of childhood adversities and COMT genotype was observed: Homozygosity for the low-active met allele and high CTQ scores was associated with a significant increment of explained ASI variance [R(2) = 0.040, false discovery rate (FDR) corrected P = 0.04]. A borderline interactive effect with respect to MAOA-uVNTR was restricted to the male subgroup. Carriers of the low-active MAOA allele who reported more aversive experiences in childhood exhibited a trend for enhanced anxious apprehension (R(2) = 0.077, FDR corrected P = 0.10). Early aversive life experiences therefore might increase the vulnerability to anxiety disorders in the presence of homozygosity for the COMT 158met allele or low-active MAOA-uVNTR alleles.

Genetic modulation of the response bias towards facial displays of anger and happiness

BACKGROUND

Investigating genetic modulation of emotion processing may contribute to the understanding of heritable mechanisms of emotional disorders. The aim of the present study was to test the effects of catechol-O-methyltransferase (COMT) val158met and serotonin-transporter-linked promoter region (5-HTTLPR) polymorphisms on facial emotion processing in healthy individuals.

METHODS

Two hundred and seventy five (167 female) participants were asked to complete a computerized facial affect recognition task, which involved four experimental conditions, each containing one type of emotional face (fearful, angry, sad or happy) intermixed with neutral faces. Participants were asked to indicate whether the face displayed an emotion or was neutral. The COMT-val158met and 5-HTTLPR polymorphisms were genotyped.

RESULTS

Met homozygotes (COMT) showed a stronger bias to perceive neutral faces as expressions of anger, compared with val homozygotes. However, the S-homozygotes (5-HTTLPR) showed a reduced bias to perceive neutral faces as expressions of happiness, compared to L-homozygotes. No interaction between 5-HTTLPR and COMT was found.

CONCLUSIONS

These results add to the knowledge of individual differences in social cognition that are modulated via serotonergic and dopaminergic systems. This potentially could contribute to the understanding of the mechanisms of susceptibility to emotional disorders.

The role of the serotonergic and GABA system in translational approaches in drug discovery for anxiety disorders

There is ample evidence that genetic factors play an important role in anxiety disorders. In support, human genome-wide association studies have implicated several novel candidate genes. However, illumination of such genetic factors involved in anxiety disorders has not resulted in novel drugs over the past decades. A complicating factor is the heterogeneous classification of anxiety disorders in the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) and diverging operationalization of anxiety used in preclinical and clinical studies. Currently, there is an increasing focus on the gene × environment (G × E) interaction in anxiety as genes do not operate in isolation and environmental factors have been found to significantly contribute to the development of anxiety disorders in at-risk individuals. Nevertheless, extensive research on G × E mechanisms in anxiety has not resulted in major breakthroughs in drug discovery. Modification of individual genes in rodent models has enabled the specific study of anxiety in preclinical studies. In this context, two extensively studied neurotransmitters involved in anxiety are the gamma-aminobutyric acid (GABA) and 5-HT (5-hydroxytryptamine) system. In this review, we illustrate the complex interplay between genes and environment in anxiety processes by reviewing preclinical and clinical studies on the serotonin transporter (5-HTT), 5-HT1A receptor, 5-HT2 receptor, and GABAA receptor. Even though targets from the serotonin and GABA system have yielded drugs with known anxiolytic efficacy, the relation between the genetic background of these targets and anxiety symptoms and development of anxiety disorders is largely unknown. The aim of this review is to show the vast complexity of genetic and environmental factors in anxiety disorders. In light of the difficulty with which common genetic variants are identified in anxiety disorders, animal models with translational validity may aid in elucidating the neurobiological background of these genes and their possible role in anxiety. We argue that, in addition to human genetic studies, translational models are essential to map anxiety-related genes and to enhance our understanding of anxiety disorders in order to develop potentially novel treatment strategies.

A possible association between panic disorder and a polymorphism in the preproghrelingene

The aim of the study was to investigate whether polymorphisms in the preproghrelin gene are associated with anxiety disorders, such as panic disorder, in humans. Panic disorder is a severe anxiety disorder, characterized by sudden attacks of intense fear or anxiety in combination with somatic symptoms. The preproghrelin gene codes for two gut-derived circulating peptides that have been linked to anxiety-like behaviour in rodents: ghrelin (an orexigenic, pro-obesity hormone) and obestatin. In the present study, we genotyped three missense mutations in the preproghrelin gene in 215 patients suffering from panic disorder and in 451 controls. The A allele of the rs4684677 polymorphism was significantly associated with panic disorder, while there were no significant associations with the two other polymorphisms studied. We conclude that the rs4684677 (Gln90Leu) polymorphism in the preproghrelin gene may be associated with increased risk of panic disorder. It will be important to confirm these findings in additional panic disorder patient groups.

Playing nice: a multi-methodological study on the effects of social conformity on memory

Conformity is an important aspect of social behavior. Two main motives have been identified: people may adapt their behavior to “play nice” despite knowing better (normative conformity) or they may accept the others' opinion as a valid source of information (informative conformity). Neuroimaging studies can help to distinguish between these two possibilities. Here, we present a functional magnetic resonance imaging (fMRI) study on memory conformity in a real group situation. We investigated the effects of group pressure on activity in hippocampus and anterior cingulate cortex (ACC) which likely support informative and normative memory conformity, respectively. Furthermore, we related the single nucleotide polymorphism (SNP) rs4680 [called Catechol-O-methyltransferase (COMT) Val158Met] on the gene coding for COMT to both behavior and fMRI activation. Homozygous Met-allele carriers (Val−) behaved more conformist than carriers of at least one Val-allele (Val+). In the neuroimaging data, we compared trials in which subjects were confronted with a majority of incorrect group responses to trials in which they were confronted with a majority of correct group responses. We found increased hippocampal activity when the majority of the group was correct, possibly indicating retrieval processes. Moreover, we observed enhanced activity in the ACC when the majority of the group was incorrect, suggesting that conformity was mostly normative. Most interestingly, this latter effect was more pronounced for Val− as compared to Val+ participants. This offers a speculative explanation for the higher behavioral levels of social conformity in Val− allele carriers, because their subjectively perceived conflict in the presence of an incorrect group majority may have been higher. Overall, this study demonstrates how the mechanisms leading to complex social behavior such as conformity can be studied by combining genetic analyses and fMRI in social neuroscience paradigms.

Interaction between catechol-O-methyltransferase (COMT) Val158Met genotype and genetic vulnerability to schizophrenia during explicit processing of aversive facial stimuli

BACKGROUND

Emotion dysregulation is a key feature of schizophrenia, a brain disorder strongly associated with genetic risk and aberrant dopamine signalling. Dopamine is inactivated by catechol-O-methyltransferase (COMT), whose gene contains a functional polymorphism (COMT Val158Met) associated with differential activity of the enzyme and with brain physiology of emotion processing. The aim of the present study was to investigate whether genetic risk for schizophrenia and COMT Val158Met genotype interact on brain activity during implicit and explicit emotion processing.

METHOD

A total of 25 patients with schizophrenia, 23 healthy siblings of patients and 24 comparison subjects genotyped for COMT Val158Met underwent functional magnetic resonance imaging during implicit and explicit processing of facial stimuli with negative emotional valence.

RESULTS

We found a main effect of diagnosis in the right amygdala, with decreased activity in patients and siblings compared with control subjects. Furthermore, a genotype × diagnosis interaction was found in the left middle frontal gyrus, such that the effect of genetic risk for schizophrenia was evident in the context of the Val/Val genotype only, i.e. the phenotype of reduced activity was present especially in Val/Val patients and siblings. Finally, a complete inversion of the COMT effect between patients and healthy subjects was found in the left striatum during explicit processing.

CONCLUSIONS

Overall, these results suggest complex interactions between genetically determined dopamine signalling and risk for schizophrenia on brain activity in the prefrontal cortex during emotion processing. On the other hand, the effects in the striatum may represent state-related epiphenomena of the disorder itself.

Meta-analysis argues for a female-specific role of MAOA-uVNTR in panic disorder in four European populations

Panic disorder (PD) is a common mental disorder, ranking highest among the anxiety disorders in terms of disease burden. The pathogenesis of PD is multifactorial with significant heritability, however only a few convincing risk genes have been reported thus far. One of the most promising candidates is the gene encoding monoamine oxidase A (MAOA), due to its key role in monoaminergic neurotransmission, established validity of animal models, and the efficacy of MAO inhibitors in the treatment of PD. A promoter repeat polymorphism in MAOA (MAOA-uVNTR) impacts on gene expression; high-expression alleles have been reported to increase the risk for PD. To further scrutinize the role of this polymorphism, we performed a formal meta-analysis on MAOA-uVNTR and PD using original data from four published European (Estonian, German, Italian, and Polish) samples and genotypes from three hitherto unpublished German PD samples, resulting in the largest (n = 1,115 patients and n = 1,260 controls) genetic study on PD reported to date. In the unpublished samples, evidence for association of MAOA-uVNTR with PD was obtained in one of the three samples. Results of the meta-analysis revealed a significant and female-specific association when calculating an allelic model (OR = 1.23, P = 0.006). This sex-specific effect might be explained by a gene-dose effect causing higher MAOA expression in females. Taken together, our meta-analysis therefore argues that high-expression MAOA-uVNTR alleles significantly increase the risk towards PD in women. However, epigenetic mechanisms might obfuscate the genetic association, calling for ascertainment in larger samples as well as assessment of the MAOA promoter methylation status therein.

No association of SIDS with two polymorphisms in genes relevant for the noradrenergic system: COMT and DBH

AIM

  Recent research suggests that genetic variance determining the strength of noradrenergic transmitting might contribute to the aetiology of SIDS. We have typed 2 functional polymorphisms of relevance for both biosynthesis and catabolism of noradrenalin: The Val158Met single-nucleotide polymorphism (SNP) of the Catechol-O-methyl transferase gene (COMT) and the 1021C/T SNP of the dopamine dehydroxylase gene (DBH).

METHODS

  COMT and DBH were typed in 171 and 196 SIDS cases and 213 and 244 controls, respectively, using PCR followed by digestion with restriction enzymes. Typing was performed using a QIAxcel automatic electrophoresis unit.

RESULTS

  Both SNPs were in Hardy-Weinberg equilibrium, and for none of these polymorphisms, an association with SIDS could be demonstrated. The allelic frequencies of the DBH locus were C: 78.32% and T: 21.68% in SIDS and C: 77.66% and T: 22.34% in controls. For the COMT locus, the allelic frequencies were A: 51.17% and G: 48.83% in SIDS and A: 52.82% and G: 47.18% in controls.

CONCLUSION

  Despite these negative results, the noradrenergic system is still an attractive candidate as modulator of SIDS risk to our eyes. There are several genes involved in this system that have not been studied up to now.

The relationship between risk-taking propensity and the COMT Val(158)Met polymorphism among early adolescents as a function of sex

Although adolescents frequently engage in a variety of risky behaviors, much remains unknown about the specific etiologies of such tendencies. Candidate genetic variants, such as the COMT Val(158)Met polymorphism, may be related to risk-taking propensity, particularly as this variant is linked to functional enzymatic differences influencing dopamine function in regions including the prefrontal cortex. The present study aimed to examine the COMT Val(158)Met variant in relation to risk-taking propensity in a community sample of youth. As part of a larger longitudinal study on adolescent risk behaviors, 223 youths (average age 11.3 years) from the metropolitan Washington D.C. area completed a measure of risk-taking propensity, the Balloon Analog Risk Task-Youth Version (BART-Y), and provided saliva samples for DNA extraction and genotyping. Results indicate that females, but not males, who are carriers of the COMT 158Met allele had higher risk-taking propensity scores on the BART-Y compared to Val homozygotes. Analyses were also conducted in the 111 European American participants, and results were consistent with those of the full sample analyses. This study represents the first investigation of a genetic substrate of risk-taking propensity, measured by a behavioral task, in youth. Results should be taken as quite preliminary, given the small sample. Implications are discussed.

Genetics of pediatric anxiety disorders

This article reviews the familiality, linkage, candidate gene, and genomewide association studies of obsessive-compulsive disorder, panic disorder, posttraumatic stress disorder, and other anxiety disorders (ie, generalized anxiety disorder, separation anxiety disorder, social phobia, and specific phobia). Studies involving children and adolescents are highlighted. Clinical and research implications are discussed.

Affect-modulated startle: interactive influence of catechol-O-methyltransferase Val158Met genotype and childhood trauma

The etiology of emotion-related disorders such as anxiety or affective disorders is considered to be complex with an interaction of biological and environmental factors. Particular evidence has accumulated for alterations in the dopaminergic and noradrenergic system--partly conferred by catechol-O-methyltransferase (COMT) gene variation--for the adenosinergic system as well as for early life trauma to constitute risk factors for those conditions. Applying a multi-level approach, in a sample of 95 healthy adults, we investigated effects of the functional COMT Val158Met polymorphism, caffeine as an adenosine A2A receptor antagonist (300 mg in a placebo-controlled intervention design) and childhood maltreatment (CTQ) as well as their interaction on the affect-modulated startle response as a neurobiologically founded defensive reflex potentially related to fear- and distress-related disorders. COMT val/val genotype significantly increased startle magnitude in response to unpleasant stimuli, while met/met homozygotes showed a blunted startle response to aversive pictures. Furthermore, significant gene-environment interaction of COMT Val158Met genotype with CTQ was discerned with more maltreatment being associated with higher startle potentiation in val/val subjects but not in met carriers. No main effect of or interaction effects with caffeine were observed. Results indicate a main as well as a GxE effect of the COMT Val158Met variant and childhood maltreatment on the affect-modulated startle reflex, supporting a complex pathogenetic model of the affect-modulated startle reflex as a basic neurobiological defensive reflex potentially related to anxiety and affective disorders.

A latent class approach to the external validation of respiratory and non-respiratory panic subtypes

BACKGROUND

The phenotypic variance observed in panic disorder (PD) appears to be best captured by a respiratory and non-respiratory panic subtype. We compared respiratory and non-respiratory panic subtypes across a series of external validators (temporal stability, psychiatric co-morbidity, treatment response) to determine whether subtypes are best conceptualized as differing: (1) only on their symptom profiles with no other differences between them; (2) on a quantitative (i.e. severity) dimension only; or (3) qualitatively from one another.

METHOD

Data from a large epidemiological survey (National Epidemiologic Survey on Alcohol and Related Conditions) and a clinical trial (Cross-National Collaborative Panic Study) were used. All analytic comparisons were examined within a latent class framework.

RESULTS

High temporal stability of panic subtypes was observed, particularly among females. Respiratory panic was associated with greater odds of lifetime major depression and a range of anxiety disorders as well as increased treatment utilization, but no demographic differences. Treatment outcome data did not suggest that the two PD subtypes were associated with differential response to either imipramine or alprazolam.

CONCLUSIONS

These data suggest that respiratory and non-respiratory panic represent valid subtypes along the PD continuum, with the respiratory variant representing a more severe form of the disorder.

ADORA2A Gene variation, caffeine, and emotional processing: a multi-level interaction on startle reflex

There is converging evidence for genetic, biochemical, and neuropsychological factors to increase the risk for anxiety and anxiety disorders. The pathogenesis of anxiety disorders is assumed to be influenced by a complex interaction of these individual risk factors on several levels, affecting intermediate phenotypes of anxiety such as the startle reflex. Thus, in the present double-blind, placebo-controlled study we attempted to paradigmatically investigate a multi-level pathogenetic model of anxiety by testing the effect of 300 mg caffeine citrate as an antagonist at the adenosine A2A receptor vs placebo on the emotion-potentiated (unpleasant, neutral, and pleasant International Affective Picture System pictures) startle reflex in 110 healthy individuals (male=56, female=54) stratified for the adenosine A2A receptor (ADORA2A) 1976T>C polymorphism (rs5751876). In addition to the expected main effect of picture category (highest startle amplitude for unpleasant, lowest for pleasant pictures) groups across all ADORA2A 1976T>C genotype and intervention (caffeine vs placebo) groups, an interaction effect of genotype, intervention, and picture category was discerned: In ADORA2A 1976TT risk genotype carriers, highest startle magnitudes were observed after caffeine administration in response to unpleasant pictures, with this effect arising particularly from the female subgroup. Our data point to a complex, multi-level, and potentially gender-specific pathogenetic model of anxiety, with genetic and biochemical factors interactively increasing the risk of maladaptive emotional processing and thereby possibly also anxiety disorders. The present findings may eventually aid in improving primary and secondary prevention by sharpening the risk profiles of anxiety-prone individuals.

Serotonin-2A receptor and catechol-O-methyltransferase polymorphisms in panic disorder

Catechol-O-methyltransferase (COMT) and serotonin receptor 2A (5HTR2A) polymorphisms have been investigated for their possible role in panic disorder (PD). The aim of this study was to investigate the genotype distribution of the COMT val158met and 5HTR2A 102T/C polymorphisms in PD. COMT val158met is a polymorphism at codon 158 that results in variations in COMT enzymatic activity with high- (H) and low-activity (L) alleles. The 5HTR2A 102T/C polymorphism comprises a T-to-C mutation at position 102. The effects of symptom severity, gender, and age of onset were also investigated. The participants were 105 outpatients with PD and 130 controls. The severity of the symptoms of PD was assessed by the Panic and Agoraphobia Scale (PAS). Polymorphisms of the 5HTR2A and COMT genes were identified using polymerase chain reaction and restriction fragment length polymorphism analysis. A significant relationship was found between the COMT Val158Met polymorphism and PD. No significant differences were found in genotype distributions or allele frequencies of the 5HTR2A polymorphisms between the PD and control groups. There were no significant relationships between the COMT and 5HTR2A polymorphisms and age of onset, gender, presence of agoraphobia, or PAS scores in the PD group (p>0.05).