Genetic and environmental sources of covariation between generalized anxiety disorder and neuroticism

Personality dimensions as common and broadband-specific features for internalizing and externalizing disorders

Several researchers have suggested that the nature of the covariation between internalizing and externalizing disorders may be understood better by examining the associations between temperament or personality and these disorders. The present study examined neuroticism as a potential common feature underlying both internalizing and externalizing disorders and novelty seeking as a potential broad-band specific feature influencing externalizing disorders alone. Participants were 12- to 18-year-old twin pairs (635 monozygotic twin pairs and 691 dizygotic twin pairs; 48 % male and 52 % female) recruited from the Colorado Center for Antisocial Drug Dependence. Genetic and nonshared environmental influences shared in common with neuroticism influenced the covariation among distinct internalizing disorders, the covariation among distinct externalizing disorders, and the covariation between internalizing and externalizing disorders. Genetic influences shared in common with novelty seeking influenced the covariation among externalizing disorders and the covariation between major depressive disorder and externalizing disorders, but not the covariation among internalizing disorders or between anxiety disorders and externalizing disorders. Also, after accounting for genetic and environmental influences shared in common with neuroticism and novelty seeking, there were no significant common genetic or environmental influences among the disorders examined, suggesting that the covariance among the disorders is sufficiently explained by neuroticism and novelty seeking. We conclude that neuroticism is a heritable common feature of both internalizing disorders and externalizing disorders, and that novelty seeking is a heritable broad-band specific factor that distinguishes anxiety disorders from externalizing disorders.

Pregabalin for the treatment of generalized anxiety disorder: an update

A PREVIOUS REVIEW SUMMARIZED WHAT WAS THEN KNOWN ABOUT THE POTENTIAL ROLE OF PREGABALIN IN THE TREATMENT OF PATIENTS WITH GENERALIZED ANXIETY DISORDER (GAD): this review provides an update on its pharmacological properties and presumed mechanism of action, the liability for abuse, and efficacy and tolerability in patients with GAD. Pregabalin has a similar molecular structure to the inhibitory neurotransmitter gamma amino butyric acid (GABA) but its mechanism of action does not appear to be mediated through effects on GABA. Instead, its anxiolytic effects may arise through high-affinity binding to the alpha-2-delta sub-unit of the P/Q type voltage-gated calcium channel in "over-excited" presynaptic neurons, thereby reducing the release of excitatory neurotransmitters such as glutamate. The findings of randomized controlled trials and meta-analyses together indicate that pregabalin is efficacious in both acute treatment and relapse prevention in GAD, with some evidence of an early onset of effect, and broad efficacy in reducing the severity of psychological and physical symptoms of anxiety. It also has efficacy as an augmenting agent after non-response to antidepressant treatment in GAD. Continuing vigilance is needed in assessing its potential abuse liability but the tolerability profile of pregabalin may confer some advantages over other pharmacological treatments in the short term for treatment in patients with GAD.

Psychoticism and Disruptive Behavior can be also Good Predictors of School Achievement

The relations of Gf (Standard Progressive Matrices Raven), Gc (verbal scale of Wechsler Intelligence Scale for Children-Third Version), personality dimensions (Eysenck Personality Questionnaire-Junior Version), and disruptive behavior (TDAH scale) with school achievement (measured by TDE test and PISA test) were investigated. Two samples of students (total N = 534) representing a broad range of socioeconomic status (SES) participated in this study. Path models were conducted. The results demonstrated that (1) in both samples no sex differences related to school achievement were found; (2) in the first sample, after controlling for age and SES differences, Gf and psychoticism predicted (.38 and −.13, respectively) school achievement (measured by TDE test); (3) in the second sample, after controlling for SES differences to which additional measures were administered, Gf and Gc positively predicted (.22 and .40, respectively) school achievement (measured by PISA test). In addition, psychoticism and disruptive behavior also predicted school performance (−.14 and −.28, respectively). Some theoretical and practical implications are discussed.

Evaluation of the unique and specific contributions of dimensions of the triple vulnerability model to the prediction of DSM-IV anxiety and mood disorder constructs

The triple vulnerability model (Barlow, 2000, 2002) posits that three vulnerabilities contribute to the etiology of emotional disorders: (1) general biological vulnerability (i.e., dimensions of temperament such as neuroticism and extraversion); (2) general psychological vulnerability (i.e., perceived control over life stress and emotional states); (3) disorder-specific psychological vulnerability (e.g., thought-action fusion for OCD). Despite the prominence of this model, a comprehensive empirical evaluation has not yet been undertaken. The current study used structural equation modeling to test the triple vulnerability model in a large clinical sample (N=700), focusing on vulnerabilities for depression, social phobia, generalized anxiety disorder (GAD), and OCD. Specifically, we examined the incremental prediction of each level of the triple vulnerability model for each disorder, with the following putative disorder-specific psychological vulnerabilities: thought-action fusion (TAF) for OCD, the dysfunctional attitudes (DAS) for depression, and intolerance of uncertainty (IoU) for GAD. In the final model that included all three levels of vulnerabilities, neuroticism had significant direct effects on all four disorder constructs, and extraversion was inversely associated with depression and social phobia. However, perceived control was significantly associated with GAD and OCD only. Of the disorder-specific psychological vulnerabilities, TAF was significantly and specifically related to OCD. In contrast, DAS and IoU were not significant predictors of depression and GAD respectively, instead contributing to other disorders. The results are discussed in regard to structural models of the emotional disorders and the various roles of general and specific vulnerability dimensions in the onset, severity, and temporal course of psychopathology.

TMPRSS9 and GRIN2B are associated with neuroticism: a genome-wide association study in a European sample

Major depression disorder (MDD) is a complex and chronic disease that ranks fourth as cause of disability worldwide. About 14 million adults in the USA are believed to have MDD, and an estimated 75 % attempt suicide making MDD a major public health problem. Neuroticism has been recognized as an endophenotype of MDD; however, few genome-wide association (GWA) analyses of neuroticism as a quantitative trait have been reported to date. The aim of this study is to identify genome-wide genetic variants affecting neuroticism using a European sample. A linear regression model was used to analyze the association with neuroticism as a continuous trait in the Netherlands Study of Depression and Anxiety and Netherlands Twin Registry population-based sample of 2,748 individuals with Perlegen 600K single nucleotide polymorphisms (SNPs). In addition, the neuroticism-associated genes/loci of the top 20 SNPs (p < 10⁻⁴) were examined with anti-social personality disorder (ASPD) in an Australian twin family study. Through GWA analysis, 32 neuroticism-associated SNPs (p < 10⁻⁴) were identified. The most significant association was observed with SNP rs4806846 within the TMPRSS9 gene (p = 7.79 × 10⁻⁶) at 19p13.3. The next best signal was in GRIN2B gene (rs220549, p = 1.05 × 10⁻⁵) at 12p12. In addition, several SNPs within GRIN2B showed borderline associations with ASPD in the Australian sample. In conclusion, these results provide a possible genetic basis for the association with neuroticism. Our findings provide a basis for replication in other populations to elucidate the potential role of these genetic variants in neuroticism and MDD along with a possible relationship between ASPD and neuroticism.

Patterns and predictors of comorbidity of DSM-IV anxiety disorders in a clinical sample of children and adolescents

This study examined the comorbidity of anxiety disorders and its predictors in a large, clinically referred sample of children and adolescents. Participants were 608 youth aged 4-18 years presenting at a large anxiety clinic for assessment and treatment of anxiety or mood related problems. The diagnoses were determined using the Anxiety Disorder Interview Schedule, Child/Parent versions. Sixty three percent of the participants had an additional diagnosis of an anxiety or depressive disorder. Comorbidity patterns differed based on the principal diagnostic category. Older children and females with anxiety were more likely to have a comorbid anxiety disorder. The presence of a medical condition increased the odds of having a comorbid anxiety disorder as well. This is the largest clinical sample of children and adolescents in which comorbidity of emotional disorders has been examined. Understanding the common patterns of comorbidity has important implications for future classification and treatment planning of childhood anxiety disorders.

Negative affect shares genetic and environmental influences with symptoms of childhood internalizing and externalizing disorders

The co-occurrence of internalizing and externalizing disorders suggests that they may have common underlying vulnerability factors. Research has shown that negative affect is moderately positively correlated with both internalizing and externalizing disorders in children. The present study is the first to provide an examination of negative affect in relation to a wide spectrum of childhood internalizing and externalizing problems using a biometric model. This study extends prior findings of more narrowly focused associations by using a factor approach including multiple disorders. The sample for this study included families of 691 same-sex 7- to 13-year old twin pairs. A multifactorial independent pathway model was used to examine the genetic and environmental influences underlying the covariation of parent-reported negative affect, internalizing symptoms, and externalizing symptoms. Results of the current study suggest that negative affect shares genetic and environmental influences with both internalizing and externalizing disorders in childhood. These common influences may partially explain their comorbidity. Understanding that negative affect is at least one contributor to the covariation among these disorders may highlight avenues for early risk assessment, intervention, and perhaps prevention.

Antidepressant effects on emotional temperament: toward a biobehavioral research paradigm for major depressive disorder

BACKGROUND

Given the limited efficacy of current pharmacotherapy for major depressive disorder (MDD) and the historical decline in antidepressant development, there is increasing clinical urgency to develop more effective treatments.

OBJECTIVES

To synthesize findings from clinical psychology and affective neuroscience related to the construct of emotional temperament; to examine the effects of antidepressants on the temperament dimensions of positive (PA) and negative affectivity (NA); and to propose a biobehavioral research paradigm for the treatment of MDD.

METHODS

We begin with an introduction to PA and NA, which emphasizes their construct development, historical context, and relevance to psychopathology. We then review studies of antidepressant effects on PA and NA, and explore two related hypotheses: (1) Cause-correction: The antidepressant response may fundamentally occur through changes in emotional temperament, with subsequent spread to syndrome or symptom changes; (2) preferential effects: Antidepressants with different mechanisms of action may have preferential effects on PA or NA.

RESULTS

Preliminary findings appear to support the cause-correction hypothesis; there is insufficient clinical evidence to support the preferential effects hypothesis.

CONCLUSIONS

PA and NA are biologically based temperament dimensions, which modulate emotional, motivational, and behavioral responses to positive and negative incentives. They can be altered by antidepressants, and may independently contribute to depression improvement. In addition, the distinct biobehavioral features of PA and NA suggest that combined pharmacological and cognitive-behavioral treatments targeting these dimensions may have specific, and perhaps, synergistic antidepressant effects.

Genetic co-morbidity between neuroticism, anxiety/depression and somatic distress in a population sample of adolescent and young adult twins

BACKGROUND

Genetic studies in adults indicate that genes influencing the personality trait of neuroticism account for substantial genetic variance in anxiety and depression and in somatic health. Here, we examine for the first time the factors underlying the relationship between neuroticism and anxiety/depressive and somatic symptoms during adolescence.

METHOD

The Somatic and Psychological Health Report (SPHERE) assessed symptoms of anxiety/depression (PSYCH-14) and somatic distress (SOMA-10) in 2459 adolescent and young adult twins [1168 complete pairs (35.4% monozygotic, 53% female)] aged 12-25 years (mean=15.5 ± 2.9). Differences between boys and girls across adolescence were explored for neuroticism, SPHERE-34, and the subscales PSYCH-14 and SOMA-10. Trivariate analyses partitioned sources of covariance in neuroticism, PSYCH-14 and SOMA-10.

RESULTS

Girls scored higher than boys on both neuroticism and SPHERE, with SPHERE scores for girls increasing slightly over time, whereas scores for boys decreased or were unchanged. Neuroticism and SPHERE scores were strongly influenced by genetic factors [heritability (h(2)) = 40-52%]. A common genetic source influenced neuroticism, PSYCH-14 and SOMA-10 (impacting PSYCH-14 more than SOMA-10). A further genetic source, independent of neuroticism, accounted for covariation specific to PSYCH-14 and SOMA-10. Environmental influences were largely specific to each measure.

CONCLUSIONS

In adolescence, genetic risk factors indexed by neuroticism contribute substantially to anxiety/depression and, to a lesser extent, perceived somatic health. Additional genetic covariation between anxiety/depressive and somatic symptoms, independent of neuroticism, had greatest influence on somatic distress, where it was equal in influence to the factor shared with neuroticism.

The effects of personality traits on quality of life

OBJECTIVE

The aim of this study was to investigate the impact of women's personality traits and some sociodemographic variables on quality of life (QoL).

METHODS

This cross-sectional and correlational study was conducted among 320 Turkish women aged between 45 and 64 years who attended the Menopausal Polyclinic. Data were collected from the Turkish version of the Cervantes Personality Scale and the Turkish version of the Menopause-Specific Quality of Life Questionnaire.

RESULTS

The mean (SD) age of the participants was 51.8 (5.3) years. The average (SD) age since menopause was found to be 46 (3.3) years. The menopausal QoL was correlated with education status, income level, working status, exercise routine, chronic health problems, family's/friends' support, and negative life events. Logistic regression analyses showed that the QoL in vasomotor, psychological, and sexual domains were 6.1, 9.2, and 11.4 times, respectively, lower in neurotic women than in emotionally stable women. In addition, the QoL in sexual domains were 3.3 times lower in introverted women than in extraverted women.

CONCLUSION

These findings indicate that higher levels of introversion and higher levels of neuroticism lead to lower QoL among postmenopausal women. The results of this study support the hypothesis that personality would play an important role in women's QoL during the transition period of menopause.

A Twin Study of Lifetime Generalized Anxiety Disorder (GAD) in Older Adults: Genetic and Environmental Influences Shared by Neuroticism and GAD

The nature of Generalized Anxiety Disorder (GAD) and worry across the lifespan remains incompletely understood. We investigated genetic and environmental influences on GAD and the proportion of genetic and environmental variation in GAD that is shared with neuroticism in older adult twins. Participants included 1618 monozygotic and 2291 same-sexed dizygotic twin pairs from the Swedish Twin Registry aged 55 to 74. Participants provided personality information in 1973 and also participated in a telephone screening between 1998 and 2002 that included an assessment for lifetime GAD. Univariate biometric models indicated that both GAD and neuroticism were moderately heritable (.27 and .47, respectively), while the balance of variation reflected environmental factors unique to the individual. Bivariate analyses indicated that approximately one third of the genetic influences on GAD were in common with genetic influences on neuroticism, while individual specific environmental influences were virtually unshared between GAD and neuroticism. Analyses of sex effects suggested that men and women differed in the frequency of lifetime GAD and level of neuroticism; however, no sex differences for genetic and environmental influences for either trait were identified.

The Genetic Architecture of Neuroticism in 3301 Dutch Adolescent Twins as a Function of Age and Sex: A Study From the Dutch Twin Register

The objective of this study was to estimate the magnitude of genetic and environmental influences to variation in adolescent neuroticism as a function of age and sex. Neuroticism was assessed using the Amsterdamse Biografische Vragenlijst (ABV): a self-report personality instrument similar in content to the Eysenck Personality Questionnaire. Genetic modeling procedures, including age as modifier, were fitted to the total sample of 3301 Dutch adolescent twins aged 12 to 17 years (mean age 15.5). Significant influences of additive genetic factors (.59, 95% confidence intervals [CI] .54–.63) and unshared environmental factors (.41, 95% CI .37–.45) were found. Our data did not support a role of shared environment. Results showed that different genes may influence variation in neuroticism between girls and boys. No interaction was found between the variance components and age. Results generally support prior findings in adults and young children that neuroticism is influenced principally by additive genetic and unique environmental factors. The magnitude of the genetic component appears higher in the present sample of adolescents than in most studies of adults. The present study suggests that, in adolescence, different genes are expressed in boys and girls.

Symptoms of Anxiety and Depression in Young Adults: Genetic and Environmental Influences on Stability and Change

Etiological factors for stability and change in symptoms of anxiety and depression, including sex differences, are largely unexplored in young adults. Using biometric modeling and two-wave longitudinal data from 4393 Norwegian twins aged 18 to 31 we explored (i) heritabilities of symptoms of anxiety and depression, (ii) effects of genetic and environmental factors on the stability and change of such symptoms, and (iii) sex-specific effects. The phenotypic cross-time correlations for symptoms of anxiety and depression were estimated to .54 and .49 for males and females, respectively. The best fitting longitudinal model specified additive genetic and individual environmental influences and emerging effects from the shared environment for females only. For both males and females, long-term stability was mainly attributable to stable additive genetic factors, whereas change was essentially related to environmental influences. Minor time-specific genetic effects were indicated, and some stable variance was due to the individual environment. Additive genetic risk factors explained 87% and 68% of the phenotypic cross-time correlation for males and females, with the unique environment accounting for the remaining covariance. The results provide strong evidence for the temporal stability of genetic risk factors for symptoms of anxiety and depression in young adults, and substantial sex-specific influences on heritability, stability and change.

The relationship between neuroticism, major depressive disorder and comorbid disorders in Chinese women

OBJECTIVE

The personality trait of neuroticism is a risk factor for major depressive disorder (MDD), but this relationship has not been demonstrated in clinical samples from Asia.

METHODS

We examined a large-scale clinical study of Chinese Han women with recurrent major depression and community-acquired controls.

RESULTS

Elevated levels of neuroticism increased the risk for lifetime MDD (with an odds ratio of 1.37 per SD), contributed to the comorbidity of MDD with anxiety disorders, and predicted the onset and severity of MDD. Our findings largely replicate those obtained in clinical populations in Europe and US but differ in two ways: we did not find a relationship between melancholia and neuroticism; we found lower mean scores for neuroticism (3.6 in our community control sample).

LIMITATIONS

Our findings do not apply to MDD in community-acquired samples and may be limited to Han Chinese women. It is not possible to determine whether the association between neuroticism and MDD reflects a causal relationship.

CONCLUSIONS

Neuroticism acts as a risk factor for MDD in Chinese women, as it does in the West and may particularly predispose to comorbidity with anxiety disorders. Cultural factors may have an important effect on its measurement.

A longitudinal etiologic model for symptoms of anxiety and depression in women

BACKGROUND

Designed as state measures to monitor treatment response, symptoms of anxiety and depression (SxAnxDep) also have trait-like characteristics. No comprehensive etiologic model for SxAnxDep has illuminated the inter-relationship between their state- and trait-like characteristics, while including key predictor variables.

METHOD

In a prospective three-wave study of 2395 female twins from the Virginia Adult Twin Study of Psychiatric and Substance Use Disorders (VATSPSUD), we examined, using structural equation modeling, how genes, childhood and past-year environmental stressors, personality and episodes of major depression (MD) and generalized anxiety disorder (GAD) influence SxAnxDep.

RESULTS

The best-fit model, which explained 68-74% of the variance in SxAnxDep, revealed two etiologic pathways. Stable levels of SxAnxDep resulted largely from neuroticism, which in turn was influenced by genetic and early environment risk factors. Occasion-specific influences resulted from stressful events mediated through episodes of MD or GAD. These two pathways, which had approximately equal influences on levels of SxAnxDep, were substantially correlated because the genetic, early environmental and personality factors that impacted on stable symptom levels also predisposed to event exposure and disorder onset. No significant interaction was seen between the two pathways.

CONCLUSIONS

SxAnxDep in women in the general population arise from two inter-related causal pathways. The first, the 'trait-like' pathway, reflects genetic and early environmental risk factors, and is mediated largely through personality. The second pathway is mediated through episodes of MD and GAD, and is the result of both recent environmental adversities and trait-like factors that influence event exposure and the probability of disorder onset.

The effects of neuroticism, extraversion, and positive and negative life events on a one-year course of depressive symptoms in euthymic previously depressed patients versus healthy controls

We investigated a) the concurrent impact of positive and negative life events on the course of depressive symptoms in persons remitted from depression and healthy controls, b) whether the impact of life events on symptom course is moderated by the history of depression and the personality traits of neuroticism and extraversion, and c) whether life events mediate possible relationships of history of depression and personality traits with symptom course. Using data from the Netherlands Study of Depression and Anxiety, we examined 239 euthymic participants with a previous depressive disorder based on DSM-IV and 450 healthy controls who completed a) baseline assessments of personality dimensions (NEO Five-Factor Inventory) and depression severity (Inventory of Depressive Symptoms [IDS]) and b) 1-year follow-up assessments of depression severity and the occurrence of positive and negative life events during the follow-up period (List of Threatening Events Questionnaire). Remitted persons reported higher IDS scores at 1-year follow-up than did the controls. Extraversion and positive and negative life events independently predicted the course of depressive symptoms. The impact of life events on symptom course was not moderated by history of depression or personality traits. The effect of extraversion on symptom course was partly caused by differential engagement in positive life events.

Psychological adjustment one year after the diagnosis of breast cancer: a prototype study of delayed post-traumatic stress disorder

OBJECTIVE. The utilization of a post-traumatic stress disorder (PTSD) diagnostic framework for categorizing the psychological adjustment of breast cancer (BC) patients has been debated. We wanted to study the prevalence of PTSD and predictors for PTSD. DESIGN. The current study is a one-year follow-up of 64 early BC patients. METHODS. PTSD, subclinical PTSD, delayed onset PTSD and several theory-driven predictive variables were examined. RESULTS. Thirteen per cent of the patients showed full symptoms of disease-related PTSD compared with 7% at the initial study (6 weeks after diagnosis). Considerable changes were observed in all PTSD clusters (intrusion, avoidance, and arousal), in most cases representing a decrease in symptom level. Immature defence style, emotional coping, avoidant behaviour, and negative affectivity were all implicated as predicting variables in a hierarchical multiple regression analysis which explained 65% of the variability of PTSD severity one year after diagnosis. CONCLUSIONS. This study highlights the PTSD diagnosis as being highly relevant in oncology settings. Early screening for the above-mentioned four variables may help early identification of the patients most at risk of developing PTSD.

The error-related negativity relates to sadness following mood induction among individuals with high neuroticism

The error-related negativity (ERN) is an event-related potential (ERP) that indexes error monitoring. Research suggests that the ERN is increased in internalizing disorders, such as depression and anxiety. Although studies indicate that the ERN is insensitive to state-related fluctuations in anxiety, few studies have carefully examined the effect of state-related changes in sadness on the ERN. In the current study, we sought to determine whether the ERN would be altered by a sad mood induction using a between-subjects design. Additionally, we explored if this relationship would be moderated by individual differences in neuroticism-a personality trait related to both anxiety and depression. Forty-seven undergraduate participants were randomly assigned to either a sad or neutral mood induction prior to performing an arrow version of the flanker task. Participants reported greater sadness following the sad than neutral mood induction; there were no significant group differences on behavioral or ERP measures. Across the entire sample, however, participants with a larger increase in sad mood from baseline to post-induction had a larger (i.e. more negative) ERN. Furthermore, this effect was larger among individuals reporting higher neuroticism. These data indicate that neuroticism moderates the relationship between the ERN and changes in sad mood.

The direct and interactive effects of neuroticism and life stress on the severity and longitudinal course of depressive symptoms

The direct and interactive effects of neuroticism and stressful life events (chronic and episodic stressors) on the severity and temporal course of depression symptoms were examined in 826 outpatients with mood and anxiety disorders, assessed on 3 occasions over a 1-year period (intake and 6- and 12-month follow-ups). Neuroticism, chronic stress, and episodic stress were uniquely associated with intake depression symptom severity. A significant interaction effect indicated that the strength of the effect of neuroticism on initial depression severity increased as chronic stress increased. Although neuroticism did not have a significant direct effect on the temporal course of depression symptoms, chronic stress significantly moderated this relationship such that neuroticism had an increasingly deleterious effect on depression symptom improvement as the level of chronic stress over follow-up increased. In addition, chronic stress (but not episodic stress) over follow-up was uniquely predictive of less depression symptom improvement. Consistent with a stress generation framework, however, initial depression symptom severity was positively associated with chronic stress during follow-up. The results are discussed in regard to diathesis-stress conceptual models of emotional disorders and the various roles of stressful life events in the onset, severity, and maintenance of depressive psychopathology.

Adult romantic attachment, negative emotionality, and depressive symptoms in middle aged men: a multivariate genetic analysis

Adult romantic attachment styles reflect ways of relating in close relationships and are associated with depression and negative emotionality. We estimated the extent to which dimensions of romantic attachment and negative emotionality share genetic or environmental risk factors in 1,237 middle-aged men in the Vietnam Era Twin Study of Aging (VETSA). A common genetic factor largely explained the covariance between attachment-related anxiety, attachment-related avoidance, depressive symptoms, and two measures of negative emotionality: Stress-Reaction (anxiety), and Alienation. Multivariate results supported genetic and environmental differences in attachment. Attachment-related anxiety and attachment-related avoidance were each influenced by additional genetic factors not shared with other measures; the genetic correlation between the attachment measure-specific genetic factors was 0.41, indicating some, but not complete overlap of genetic factors. Genetically informative longitudinal studies on attachment relationship dimensions can help to illuminate the role of relationship-based risk factors in healthy aging.

Temperament und soziale Reaktivität bei Autismus-Spektrum-Störungen und ADHS

Fragestellung: Vorliegende Untersuchung beschäftigt sich mit der Frage, ob spezifische Temperaments- und Persönlichkeitskonstellationen bei Kindern mit Autismus-Spektrum-Störungen (ASD) im Vergleich zu Kindern mit einfacher Aufmerksamkeitsdefizit-Hyperaktivitätsstörung (ADHS) bereits im Kindesalter zu finden sind und inwiefern diese Persönlichkeitsmerkmale soziale und kommunikative Schwierigkeiten beeinflussen. Methodik: Untersucht wurden insgesamt 68 Kinder mit ADHS (n = 32) oder ASD (n = 36); die Angaben über Persönlichkeit und Sozialverhalten der Kinder wurden mittels des Junior Temperament- und Charakterinventars (JTCI 7–11 R) sowie der sozialen Reaktivitätsskala (SRS) erfasst. Die Diagnose einer ASD wurde mittels standardisierter diagnostischer Verfahren erhoben (ADOS und ADI-R) Ergebnisse: Sowohl Kinder mit ASD als auch mit ADHS zeigten gegenüber Normstichproben deutlich erniedrigte Werte im Beharrungsvermögen, in der Selbstlenkungsfähigkeit und der Kooperativität. Darüber hinaus zeigten Kinder mit ASD extrem erniedrigte Werte in der Belohnungsabhängigkeit. Sie unterschieden sich signifikant von Kindern mit ADHS sowohl hinsichtlich der Temperamentsmerkmale Schadensvermeidung und Belohnungsabhängigkeit als auch in den Charakterdimensionen Selbstlenkungsfähigkeit und Kooperativität. Soziale Schwierigkeiten, erfasst mit dem SRS, waren bei beiden Gruppen deutlich durch Persönlichkeitsvariablen, vor allem der Temperamentsdimension Belohnungsabhängigkeit, beeinflusst. Schlussfolgerung: Die Ergebnisse der vorliegenden Untersuchung lassen vermuten, dass spezifische Persönlichkeitskonstellationen bei Kindern mit ASD und ADHS bereits früh bestehen und auf deren soziale Fertigkeiten einwirken.

Conceptual background, development, and preliminary data from the unified protocol for transdiagnostic treatment of emotional disorders

Anxiety and mood disorders are common, chronic, costly, and characterized by high comorbidity. The development of cognitive behavioral approaches to treating anxiety and mood disorders has left us with highly efficacious treatments that are increasingly widely accepted. The proliferation of treatment manuals targeting single disorders, sometimes with trivial differences among them, leaves the mental health professional with no clear way to choose one manual over another and little chance of ever becoming familiar with most of them, let alone trained to competence in their delivery. Deepening understanding of the nature of emotional disorders reveals that commonalities in etiology and latent structures among these disorders supersedes differences. Based on empirical evidence from the domains of learning, emotional development and regulation, and cognitive science, we have distilled a set of psychological procedures that comprise a unified intervention for emotional disorders. The Unified Protocol (UP) is a transdiagnostic, emotion-focused cognitive behavioral treatment, which emphasizes the adaptive, functional nature of emotions, and seeks to identify and correct maladaptive attempts to regulate emotional experiences, thereby facilitating appropriate processing and extinction of excessive emotional responding to both internal (somatic) and external cues. The treatment components of the UP are briefly outlined. Theory and rationale supporting this new approach are described along with some preliminary evidence supporting its efficacy. Implications for the treatment of emotional disorders using the UP are discussed.

A genome-wide association study of neuroticism in a population-based sample

Neuroticism is a moderately heritable personality trait considered to be a risk factor for developing major depression, anxiety disorders and dementia. We performed a genome-wide association study in 2,235 participants drawn from a population-based study of neuroticism, making this the largest association study for neuroticism to date. Neuroticism was measured by the Eysenck Personality Questionnaire. After Quality Control, we analysed 430,000 autosomal SNPs together with an additional 1.2 million SNPs imputed with high quality from the Hap Map CEU samples. We found a very small effect of population stratification, corrected using one principal component, and some cryptic kinship that required no correction. NKAIN2 showed suggestive evidence of association with neuroticism as a main effect (p<10⁻⁶) and GPC6 showed suggestive evidence for interaction with age (p≈10⁻⁷). We found support for one previously-reported association (PDE4D), but failed to replicate other recent reports. These results suggest common SNP variation does not strongly influence neuroticism. Our study was powered to detect almost all SNPs explaining at least 2% of heritability, and so our results effectively exclude the existence of loci having a major effect on neuroticism.

A hierarchical model for the relationships between general and specific vulnerability factors and symptom levels of generalized anxiety disorder

The present study examined a hierarchical model for the relationships between general and specific vulnerability factors and symptom manifestations of generalized anxiety disorder (GAD). A clinical sample of patients with GAD (N=137) completed a set of self-report questionnaires for measuring neuroticism, extraversion, intolerance of uncertainty, metacognitive beliefs, and symptoms of generalized anxiety (i.e., worry) and depression. A bootstrapping analysis yielded support for a model in which the relation between the general vulnerability factor of neuroticism and symptoms of GAD were mediated by the specific vulnerability factors of intolerance of uncertainty and negative metacognitions. Implications for the classification and treatment of GAD are discussed.

Emotional disorders: cluster 4 of the proposed meta-structure for DSM-V and ICD-11

BACKGROUND

The extant major psychiatric classifications DSM-IV, and ICD-10, are atheoretical and largely descriptive. Although this achieves good reliability, the validity of a medical diagnosis would be greatly enhanced by an understanding of risk factors and clinical manifestations. In an effort to group mental disorders on the basis of aetiology, five clusters have been proposed. This paper considers the validity of the fourth cluster, emotional disorders, within that proposal.

METHOD

We reviewed the literature in relation to 11 validating criteria proposed by a Study Group of the DSM-V Task Force, as applied to the cluster of emotional disorders.

RESULTS

An emotional cluster of disorders identified using the 11 validators is feasible. Negative affectivity is the defining feature of the emotional cluster. Although there are differences between disorders in the remaining validating criteria, there are similarities that support the feasibility of an emotional cluster. Strong intra-cluster co-morbidity may reflect the action of common risk factors and also shared higher-order symptom dimensions in these emotional disorders.

CONCLUSION

Emotional disorders meet many of the salient criteria proposed by the Study Group of the DSM-V Task Force to suggest a classification cluster.

The influence of temperament on symptoms and functional outcome in people with psychosis in the Northern Finland 1966 Birth Cohort

OBJECTIVE

To describe symptom expression and functional outcome in psychotic disorders in relation with temperament traits assessed with the Temperament and Character Inventory (TCI) in a population-based sample.

METHOD

As part of the 31-year follow-up survey of the Northern Finland 1966 Birth Cohort, TCI temperament items were filled in by 4349 members of the cohort. In individuals with psychotic disorders, also positive and negative symptoms and outcome variables were assessed in a 35-year follow-up. Information of TCI and outcomes were available for altogether 41 individuals with psychosis.

RESULT

Reward dependence (RD) (rho=-0.45) and Persistence (P) (rho=-0.52) were significantly correlated with Positive and Negative Syndrome Scale (PANSS) negative symptoms. Higher P scores predicted higher social and occupational functioning (as measured by Social and Occupational Functioning Assessment Scale [SOFAS]), and higher Harm avoidance (HA) predicted a higher likelihood of being on a disability pension.

CONCLUSION

Results indicate that understanding of personality dimensions support better understanding of outcome and symptom expressions in psychotic disorders.

The serotonin-1A receptor in anxiety disorders

The serotonin system plays an important role in the neural processing of anxiety. The involvement of the main inhibitory serotonergic receptor, the serotonin-1A (5-HT1A) subtype, in dysfunctional forms of anxiety has been supported by findings from a wide range of preclinical research and clinical trials, including treatment studies, genetic research, and neuroimaging data. The following article summarizes preclinical results with a focus on 5-HT1A receptor knockout and transgenic mice as genetic models of anxiety. Behavioral, autonomic, and endocrinological changes in these mice are reported. This article also presents genetic polymorphisms in humans associated with increased anxiety scores and pharmacological data focused on 5-HT1A receptor agonists and antagonists. Furthermore, molecular neuroimaging results are presented. Recent positron emission tomography (PET) studies have reported reduced 5-HT1A receptor binding in patients with panic disorder and social anxiety disorder, but not in posttraumatic stress disorder. In healthy subjects, increased anxiety scores might be associated with lower 5-HT1A receptor binding. This overview of preclinical and clinical data provides strong evidence for the key role of the 5-HT1A receptor in the serotonergic dysregulation of anxiety disorders.

Emotion regulation deficits in generalized anxiety disorder, social anxiety disorder, and their co-occurrence

Preliminary evidence supports the role of emotion-related deficits in generalized anxiety disorder (GAD), including heightened emotional intensity, poor understanding of emotion, negative cognitive reactivity to emotions, and maladaptive emotion management. However, questions remain concerning the specificity of these emotion-related deficits compared to highly comorbid conditions such as social anxiety disorder (SAD). In the current study, 113 undergraduate students were administered measures of GAD, SAD, and emotion-related factors in order to clarify relationships among these variables. In univariate analyses, presence of SAD did not significantly impact the association between GAD and the emotion-related measures. Further, a discriminant function analysis revealed that emotional intensity and impaired regulation strategies provided the greatest discrimination between groups and best predicted a diagnosis of GAD (regardless of SAD comorbidity). Although their discriminatory ability was weaker, poor emotional understanding best predicted a diagnosis of SAD (regardless of GAD comorbidity), and non-acceptance of emotions best predicted comorbid GAD and SAD.

Predictors of clinical improvement in a randomized effectiveness trial for primary care patients with panic disorder

This study's aim was to prospectively examine and identify a model of demographic, clinical, and attitudinal variables that impact improvement among patients with panic disorder. Subjects were 232 primary care patients meeting criteria for DSM-IV panic disorder. Eligible patients were randomly assigned to a collaborative care intervention or to treatment as usual. Assessments occurred at 3-month intervals during the course of 1 year. In final multivariate logistic regression models, patients with higher anxiety sensitivity and higher neuroticism scores at baseline were less likely to show clinical improvement (using a criterion of 20 or less on the Anxiety Sensitivity Index) at 3 months. Those who were non-white, had higher anxiety sensitivity, and higher overall phobic avoidance at baseline were less likely to show clinical improvement at 12 months. A greater understanding of these predictors may help clinicians identify who is at greatest risk for persistent panic-related symptoms and to plan the intensity of interventions accordingly.

Correlates of comorbid mental disorders in a regional community-based sample

OBJECTIVE

The common coexistence of psychiatric disorders has been identified as a significant factor contributing to the disability associated with mental illness. Identifying indicators to the development of coexisting disorders has potential clinical implications. This study aimed to investigate the correlates and impact of coexisting disorders in a rural setting.

DESIGN

Cross-sectional analyses of data from a cohort interviewed in two phases.

SETTING

A regional community sample in Northern New South Wales, Australia.

PARTICIPANTS

A total of 1407 participants were interviewed and 968 were re-interviewed at follow up.

MAIN OUTCOME MEASURES

Multinomial logistic regression modelling compared subjects with multiple psychiatric disorders with those with a single disorder for sociodemographic characteristics, measures of personal and social vulnerability, psychological distress, functional disabilities and help-seeking behaviours.

RESULTS

Participants with coexisting disorders were more likely to be male, report a history of severe childhood assault and had higher levels of neuroticism, psychological distress and help-seeking behaviour.

CONCLUSIONS

The findings suggest the role of early developmental factors on the complexity and severity of adult mental illness in a rural setting and the significant clinical consequences of comorbidity.

The role of personality in comorbidity among anxiety and depressive disorders in primary care and specialty care: a cross-sectional analysis

OBJECTIVE

Almost no cross-sectional studies directly compared the rate and pattern of comorbidity of affective disorders in relation to personality traits of patients seen in primary care versus specialty mental health care.

METHOD

Using data from the Netherlands Study of Depression and Anxiety, we compared 1086 primary care patients with 790 consecutive specialized mental health care patients. All participants had at least one lifetime Diagnostic and Statistical Manual for Mental Disorders, Fourth Edition-based diagnosis of depression or anxiety. Personality was assessed with the NEO Five-Factor Inventory.

RESULTS

In both settings it was common to have at least one lifetime comorbid affective disorder. Compared to primary care patients, specialty care patients showed elevated scores for Neuroticism and lower scores for Extraversion and Conscientiousness. The odds of having another disorder given any one disorder was no longer significant after accounting for personality dimensions. Only Neuroticism proved to be positively associated with comorbidity per se.

CONCLUSIONS

Prevalence of and comorbidity among anxiety and depressive disorders in primary care were very similar to those in specialty care. Neuroticism - but no other personality traits - may help to understand the comorbidity among anxiety and depressive disorders irrespective of recruitment setting.

A proposal for a dimensional classification system based on the shared features of the DSM-IV anxiety and mood disorders: implications for assessment and treatment

A wealth of evidence attests to the extensive current and lifetime diagnostic comorbidity of the Diagnostic and Statistical Manual of Mental Disorders (4th ed., DSM-IV) anxiety and mood disorders. Research has shown that the considerable cross-sectional covariation of DSM-IV emotional disorders is accounted for by common higher order dimensions such as neuroticism/behavioral inhibition (N/BI) and low positive affect/behavioral activation. Longitudinal studies indicate that the temporal covariation of these disorders can be explained by changes in N/BI and, in some cases, initial levels of N/BI are predictive of the temporal course of emotional disorders. The marked phenotypal overlap of the DSM-IV anxiety and mood disorders is a frequent source of diagnostic unreliability (e.g., temporal overlap in the shared features of generalized anxiety disorder and mood disorders, situation specificity of panic attacks in panic disorder and specific phobia). Although extant dimensional proposals may address some drawbacks associated with the DSM nosology (e.g., inadequate assessment of individual differences in disorder severity), these proposals do not reconcile key problems in current classification, such as modest reliability and high comorbidity. This article considers an alternative approach that emphasizes empirically supported common dimensions of emotional disorders over disorder-specific criteria sets. Selection and assessment of these dimensions are discussed along with how these methods could be implemented to promote more reliable and valid diagnosis, prognosis, and treatment planning. For instance, the advantages of this system are discussed in context of transdiagnostic treatment protocols that are efficaciously applied to a variety of disorders by targeting their shared features.

Anxiety: its role in the history of psychiatric epidemiology

BACKGROUND

The role played by anxiety in the history of psychiatric epidemiology has not been well recognized. Such lack of understanding retarded the incremental growth of psychiatric research in general populations. It seems useful to look back on this history while deliberations are being carried out about how anxiety will be presented in DSM-V.

METHOD

Drawing on the literature and our own research, we examined work that was carried out during and after the Second World War by a Research Branch of the United States War Department, by the Stirling County Study, and by the Midtown Manhattan Study. The differential influences of Meyerian psychobiology and Freudian psychoanalysis are noted.

RESULTS

The instruments developed in the early epidemiologic endeavors used questions about nervousness, palpitations, sweating, trembling, shortness of breath, upset stomach, etc. These symptoms are important features of what the clinical literature called 'manifest', 'free-floating' or 'chronic anxiety'. A useful descriptive name is 'autonomic anxiety'.

CONCLUSIONS

Although not focusing on specific circumstances as in Panic and Phobic disorders, a non-specific form of autonomic anxiety is a common, disabling and usually chronic disorder that received empirical verification in studies of several community populations. It is suggested that two types of general anxiety may need to be recognized, one dominated by excessive worry and feelings of stress, as in the current DSM-IV definition of Generalized Anxiety Disorder (GAD), and another emphasizing frequent unexplainable autonomic fearfulness, as in the early epidemiologic studies.

Animal models of gene-environment interactions in schizophrenia

The pathogenesis of schizophrenia and related mental illnesses likely involves multiple interactions between susceptibility genes of small effects and environmental factors. Gene-environment interactions occur across different stages of neurodevelopment to produce heterogeneous clinical and pathological manifestations of the disease. The main obstacle for mechanistic studies of gene-environment interplay has been the paucity of appropriate experimental systems for elucidating the molecular pathways that mediate gene-environment interactions relevant to schizophrenia. Recent advances in psychiatric genetics and a plethora of experimental data from animal studies allow us to suggest a new approach to gene-environment interactions in schizophrenia. We propose that animal models based on identified genetic mutations and measurable environment factors will help advance studies of the molecular mechanisms of gene-environment interplay.

Identification of quantitative trait loci for locomotor activation and anxiety using closely related inbred strains

We carried out a quantitative trait loci (QTL) mapping experiment in two phenotypically similar inbred mouse strains, C57BL/6J and C58/J, using the open-field assay, a well-established model of anxiety-related behavior in rodents. This intercross was initially carried out as a control cross for an ethylnitrosurea mutagenesis mapping study. Surprisingly, although open-field behavior is similar in the two strains, we identified significant QTL in their F2 progeny. Marker regression identified a locus on Chr 8 having associations with multiple open-field measures and a significant interaction between loci on Chr 13 and 17. Together, the Chr 8 locus and the interaction effect form the core set of QTL controlling these behaviors with additional loci on Chr 1 and 6 present in a subset of the behaviors.

Relationships of neuroticism and extraversion with axis I and II comorbidity among patients with DSM-IV major depressive disorder

BACKGROUND

High comorbidity with axis I and II disorders among major depressive disorder (MDD) patients may in part be due to the predisposing personality dimensions of neuroticism and extraversion. However, a comprehensive view of this relationship is lacking.

METHODS

MDD patients (n=193) in the Vantaa Depression Study were interviewed at baseline and at 6 and 18 months with the SCAN and SCID-II, and a general population comparison group (n=388) surveyed by mail. Neuroticism and extraversion were measured with the Eysenck Personality Inventory. A dose-exposure relationship between standardized levels of neuroticism and extraversion and type and number of comorbid axis I and II disorders among patients with MDD was hypothesized.

RESULTS

Prevalence and number of comorbid axis I and II disorders increased significantly with increasing level of neuroticism. In contrast, as the level of extraversion increased, the prevalences of social phobia and cluster C personality disorders decreased. Patients with pure MDD or with any comorbid axis I or II disorder had z-scores of neuroticism of +0.46, +0.90 and +1.30 and of extraversion of -0.34, -0.47 and -0.84, respectively.

LIMITATIONS

Patients' personality scores were not pre-morbid.

CONCLUSION

Among MDD patients, a positive dose-exposure relationship appears to exist between neuroticism and prevalence and number of comorbid axis I and II disorders. A negative relationship exists between level of extraversion and prevalence of social phobia and cluster C personality disorders. These findings are consistent with the hypothesis that high neuroticism and low extraversion predispose to comorbid axis I and II disorders among patients with MDD.

Risk factors predict post-traumatic stress disorder differently in men and women

BACKGROUND

About twice as many women as men develop post-traumatic stress disorder (PTSD), even though men as a group are exposed to more traumatic events. Exposure to different trauma types does not sufficiently explain why women are more vulnerable.

METHODS

The present work examines the effect of age, previous trauma, negative affectivity (NA), anxiety, depression, persistent dissociation, and social support on PTSD separately in men and women. Subjects were exposed to either a series of explosions in a firework factory near a residential area or to a high school stabbing incident.

RESULTS

Some gender differences were found in the predictive power of well known risk factors for PTSD. Anxiety predicted PTSD in men, but not in women, whereas the opposite was found for depression. Dissociation was a better predictor for PTSD in women than in men in the explosion sample but not in the stabbing sample. Initially, NA predicted PTSD better in women than men in the explosion sample, but when compared only to other significant risk factors, it significantly predicted PTSD for both men and women in both studies. Previous traumatic events and age did not significantly predict PTSD in either gender.

CONCLUSION

Gender differences in the predictive value of social support on PTSD appear to be very complex, and no clear conclusions can be made based on the two studies included in this article.

The error-related negativity (ERN) and psychopathology: toward an endophenotype

The ERN is a negative deflection in the event-related potential that peaks approximately 50 ms after the commission of an error. The ERN is thought to reflect early error-processing activity of the anterior cingulate cortex (ACC). First, we review current functional, neurobiological, and developmental data on the ERN. Next, the ERN is discussed in terms of three psychiatric disorders characterized by abnormal response monitoring: anxiety disorders, depression, and substance abuse. These data indicate that increased and decreased error-related brain activity is associated with the internalizing and externalizing dimensions of psychopathology, respectively. Recent data further suggest that abnormal error-processing indexed by the ERN indexes trait- but not state-related symptoms, especially related to anxiety. Overall, these data point to utility of ERN in studying risk for psychiatric disorders, and are discussed in terms of the endophenotype construct.

Human-mouse quantitative trait locus concordance and the dissection of a human neuroticism locus

BACKGROUND

Exploiting synteny between mouse and human disease loci has been proposed as a cost-effective method for the identification of human susceptibility genes. Here we explore its utility in an analysis of a human personality trait, neuroticism, which can be modeled in mice by tests of emotionality. We investigated a mouse emotionality locus on chromosome 1 that contains no annotated genes but abuts four regulators of G protein signaling, one of which (rgs2) has been previously identified as a quantitative trait gene for emotionality. This locus is syntenic with a human region that has been consistently implicated in the genetic aetiology of neuroticism.

METHODS

The functional candidacy of 29 murine sequence variants was tested by a combination of gel shift and transient transfection assays. Murine sequences that contained functional variants and exhibited significant cross-species conservation were prioritized for investigation in humans. Genetic association with neuroticism was tested in 1869 high and 2032 low unrelated individuals scored for neuroticism, selected from the extremes of 88,141 people from southwest England.

RESULTS

Fifteen sequence variants contributed to variation in the expression of rgs18, the gene lying at the edge of the quantitative trait loci (QTL) interval. There was no evidence of association between neuroticism and single nucleotide polymorphisms (SNPs) lying in the human regions homologous to those of mouse functional variants. One SNP, rs6428058, in a region of sequence conservation 644 kb upstream of RGS18, showed significant association (p = .000631).

CONCLUSIONS

It is unlikely that a single variant is responsible for the mouse emotionality locus on chromosome 1. This level of underlying genetic complexity means that although cross-species QTL concordance may be invaluable for the identification of human disease loci, it is unlikely to be as informative in the identification of human disease-causing variants.

Cortisol and ACTH responses to the Dex/CRH test: influence of temperament

Temperament and personality traits such as neuroticism and behavioral inhibition are prospective predictors of the onset of depression and anxiety disorders. Exposure to stress is also linked to the development of these disorders, and neuroticism and inhibition may confer or reflect sensitivity to stressors. Several lines of research have documented hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis in some patients with major depression, as well as in children and non-human primates with inhibited temperaments. The present investigation tested the hypothesis that stress-reactive temperaments would be predictive of plasma adrenocorticotropin (ACTH) and cortisol concentrations in the dexamethasone/corticotropin-releasing hormone (Dex/CRH) test. Sixty adults completed diagnostic interviews and questionnaires assessing the temperament domains of novelty seeking and harm avoidance and symptoms of anxiety and depression. All subjects were free of any current or past Axis I psychiatric disorder. The Dex/CRH test was performed on a separate visit. A repeated-measures general linear model (GLM) showed a main effect of harm avoidance in predicting cortisol concentrations in the test (F(1, 58)=4.86, p<.05). The GLM for novelty seeking and cortisol response also showed a main effect (F(1, 58)=5.28, p<.05). Higher cortisol concentrations were associated with higher levels of harm avoidance and lower levels of novelty seeking. A significant interaction of time with harm avoidance and novelty seeking (F(4, 53)=3.37, p<.05) revealed that participants with both high levels of harm avoidance and low levels of novelty seeking had the highest cortisol responses to the Dex/CRH test. Plasma ACTH concentrations did not differ as a function of temperament. The results indicate that temperament traits linked to sensitivity to negative stimuli are associated with greater cortisol reactivity during the Dex/CRH test. Increased adrenocortical reactivity, which previously has been linked to major depression and anxiety disorders, may contribute to the association between temperament/personality traits and these disorders.

Finding gene-environment interactions for generalised anxiety disorder

It is becoming increasingly apparent that genetic research into psychiatric disorders would benefit from consideration of the environment because these risk mechanisms are likely to interact. Despite generalised anxiety disorder (GAD) being one of the most prevalent disorders presented in primary care, there is a paucity of published studies of gene-environment interactions (G x E) for this phenotype. This article describes how our current knowledge of GAD is useful in designing studies of G x E for GAD. To increase the chances of identifying replicable G x E for GAD further information is needed with regards to: defining and measuring GAD, difficulties co-occurring with GAD, quantitative genetic estimations for GAD, specific genes associated with GAD, and specific environmental risks for GAD.

Association of the dopamine D4 receptor (DRD4) gene and approach-related personality traits: meta-analysis and new data

BACKGROUND

Two variants in the dopamine D4 receptor (DRD4) gene have been reported to be associated with human approach-related traits such as novelty seeking and extraversion. However, the strength of evidence for this association remains uncertain.

METHODS

We conducted a meta-analysis of published studies of the association between the DRD4 gene variable number of tandem repeats (VNTR) and C-521T polymorphisms and human approach-related personality traits, including novelty seeking, extraversion, and impulsivity, restricted to adult samples recruited from nonpsychiatric populations, and extended on this literature by attempting to confirm any evidence of association in a replication sample (n = 309) selected for extreme scores on the extraversion subscale of the Eysenck Personality Questionnaire from a large (n = 40,090) population-based sample.

RESULTS

Our initial meta-analysis supported the association of the DRD4 C-521T polymorphism, but not the VNTR polymorphism, with approach-related traits. This conclusion was qualified by evidence of significant publication bias and the failure to detect association in a replication sample comprising individuals at the extremes of the trait distribution. The association of the C-521T polymorphism observed in our initial meta-analysis was robust to the inclusion of these new data, but our revised meta-analysis indicated that the association was present for measures of novelty seeking and impulsivity but not for measures of extraversion.

CONCLUSIONS

The DRD4 gene may be associated with measures of novelty seeking and impulsivity but not extraversion. The association of the C-521T variant with these measures, if genuine, may account for up to 3% of phenotypic variance.

Is generalized anxiety disorder an anxiety or mood disorder? Considering multiple factors as we ponder the fate of GAD

Generalized anxiety disorder (GAD) and major depressive disorder (MDD) demonstrate a strong relationship to each other at both genotypic and phenotypic levels, and both demonstrate substantial loadings on a higher-order negative affectivity factor [see Watson, 2005: J Abnorm Psychol 114:522-536]. On the basis of these findings, there have been a number of calls to reclassify GAD in the same category as MDD (the "distress disorders"). However, any consideration of the reclassification of GAD should also take into account a number of other factors not only related to GAD and MDD but also to the overlap of these disorders with other anxiety and mood disorders. First, GAD has established reliability and validity in its own right, and specific features (e.g., worry) may become obscured by attempts at reclassification. Second, examination of the nature of the overlap of GAD and MDD with each other and with other disorders suggests a more complex pattern of differences between these conditions than has been suggested (e.g., MDD has strong relationships with other anxiety disorders, and GAD may be more strongly related to fear than it may first appear). Third, although findings suggest that GAD and MDD may have overlapping heritable characteristics, other evidence suggests that the two disorders may be distinguished by both environmental factors and temporal presentations. Finally, although overlap between GAD and MDD is reflected in their relationships to negative affectivity, temporal relationships between these disorders may be demonstrated by functional changes in emotional responsivity.