Why do measures of normal and disordered personality correlate? A study of genetic comorbidity

Insecure attachment and personality disorder: a twin study of adults

This study used 239 twin pairs from a volunteer community sample to investigate how anxious and avoidant attachment are related to personality disorder (PD). Factor analysis showed that self‐reported anxious attachment and 11 PD scales from the Dimensional Assessment of Personality Problems loaded onto one factor (emotional dysregulation), and avoidant attachment and four PD scales loaded onto a second factor (inhibitedness). Biometric models indicated that 40% of the variance in anxious attachment was heritable, and 63% of its association with corresponding PD dimensions was attributable to common genetic effects. Avoidant attachment was influenced by the shared environment instead of genes. Correlations between avoidance and corresponding PD dimensions were attributable to experiences in the nonshared environment that influenced both variables. Copyright © 2006 John Wiley & Sons, Ltd.

The structure of genetic and environmental influences on normative personality, abnormal personality traits, and personality disorder symptoms

BACKGROUND

Can the structure of genetic and environmental influences on normative personality traits (NPTs), abnormal personality traits (APTs), and DSM-IV criteria for personality disorders (PD) fit a high or low congruence model positing, respectively, close or more limited etiologic continuity?

METHOD

Exploratory factor analysis was applied to transformed correlation matrices from Cholesky twin decompositions obtained in OpenMx. In 2801 adult twins from the Norwegian Institute of Public Health Twin Panel, NPTs and APTs were assessed by self-report using the Big Five Inventory (BFI) and PID-5-Norwegian Brief Form (PID-5-NBF), respectively. PDs were assessed at interview using the Structured Interview for DSM-IV Personality (SIDP-IV).

RESULTS

The best model yielded three genetic and three unique environmental factors. Genetic factors were dominated, respectively, by (i) high loadings on nearly all PDs and NPT/APT neuroticism and compulsivity, (ii) negative loadings on NPT agreeableness/conscientiousness and positive loadings on APT/PD measures of antisocial traits, and (iii) negative loadings on NPT extraversion and histrionic PD, and positive loadings on APT detachment and schizoid/avoidant PD. Unique environmental factors were dominated, by (i) high loadings on all PDs, (ii) high loadings on all APT dimensions and NPT neuroticism, and (iii) negative loadings on NPT extraversion and positive loadings on NPT detachment/avoidant PD.

CONCLUSIONS

Two genetic and one environmental common factor were consistent with a high congruence model while one genetic and two environmental factors were more supportive of a low congruence model. The relationship between genetic and environmental influences on personality assessed by NPTs, APTs, and PDs is complex and does not fit easily into a low or high congruence model.

A Twin Study of Normative Personality and DSM-IV Personality Disorder Criterion Counts: Evidence for Separate Genetic Influences

OBJECTIVE

Both normative personality and DSM-IV personality disorders have been found to be heritable. However, there is limited knowledge about the extent to which the genetic and environmental influences underlying DSM personality disorders are shared with those of normative personality. The aims of this study were to assess the phenotypic similarity between normative and pathological personality and to investigate the extent to which genetic and environmental influences underlying individual differences in normative personality account for symptom variance across DSM-IV personality disorders.

METHOD

A large population-based sample of adult twins was assessed for DSM-IV personality disorder criteria with structured interviews at two waves spanning a 10-year interval. At the second assessment, participants also completed the Big Five Inventory, a self-report instrument assessing the five-factor normative personality model. The proportion of genetic and environmental liabilities unique to the individual personality disorder measures, and hence not shared with the five Big Five Inventory domains, were estimated by means of multivariate Cholesky twin decompositions.

RESULTS

The median percentage of genetic liability to the 10 DSM-IV personality disorders assessed at wave 1 that was not shared with the Big Five domains was 64%, whereas for the six personality disorders that were assessed concurrently at wave 2, the median was 39%. Conversely, the median proportions of unique environmental liability in the personality disorders for wave 1 and wave 2 were 97% and 96%, respectively.

CONCLUSIONS

The results indicate that a moderate-to-sizable proportion of the genetic influence underlying DSM-IV personality disorders is not shared with the domain constructs of the Big Five model of normative personality. Caution should be exercised in assuming that normative personality measures can serve as proxies for DSM personality disorders when investigating the etiology of these disorders.

Personality dimensions in schizophrenia: A family study

Studies have demonstrated that personality traits differ in schizophrenia patients and family members compared to controls, suggesting familial risk. This study evaluated personality traits in a family study of schizophrenia, as well as the relationship between personality traits and symptoms and social functioning in schizophrenia patients. Thirty-two schizophrenia patients, 28 adult non-psychotic relatives, and 27 community controls completed the Dimensional Assessment of Personality Pathology-Basic Questionnaire (DAPP-BQ). Schizophrenia patients differed on many dimensions of the DAPP-BQ compared to controls and/or relatives: affective lability, anxiousness, callousness, conduct problems, cognitive dysregulation, identity problem, intimacy, insecure attachment, low affiliation, narcissism, oppositionality, restricted expression, self-harm, submissiveness, and suspiciousness. No differences were found between relatives and controls. Furthermore, in schizophrenia patients, associations were found between personality and particularly general symptoms, as well as social functioning. Personality traits can be conceptualized as an extended phenotype in schizophrenia patients.

The Genetic and Environmental Sources of Resemblance Between Normative Personality and Personality Disorder Traits

Recent work has suggested a high level of congruence between normative personality, most typically represented by the "big five" factors, and abnormal personality traits. In 2,293 Norwegian adult twins ascertained from a population-based registry, the authors evaluated the degree of sharing of genetic and environmental influences on normative personality, assessed by the Big Five Inventory (BFI), and personality disorder traits (PDTs), assessed by the Personality Inventory for DSM-5-Norwegian Brief Form (PID-5-NBF). For four of the five BFI dimensions, the strongest genetic correlation was observed with the expected PID-5-NBF dimension (e.g., neuroticism with negative affectivity [+], conscientiousness with disinhibition [-]). However, neuroticism, conscientiousness, and agreeableness had substantial genetic correlations with other PID-5-NBF dimensions (e.g., neuroticism with compulsivity [+], agreeableness with detachment [-]). Openness had no substantial genetic correlations with any PID-5-NBF dimension. The proportion of genetic risk factors shared in aggregate between the BFI traits and the PID-5-NBF dimensions was quite high for conscientiousness and neuroticism, relatively robust for extraversion and agreeableness, but quite low for openness. Of the six PID-5-NBF dimensions, three (negative affectivity, detachment, and disinhibition) shared, in aggregate, most of their genetic risk factors with normative personality traits. Genetic factors underlying psychoticism, antagonism, and compulsivity were shared to a lesser extent, suggesting that they are influenced by etiological factors not well indexed by the BFI.

A hierarchical causal taxonomy of psychopathology across the life span

We propose a taxonomy of psychopathology based on patterns of shared causal influences identified in a review of multivariate behavior genetic studies that distinguish genetic and environmental influences that are either common to multiple dimensions of psychopathology or unique to each dimension. At the phenotypic level, first-order dimensions are defined by correlations among symptoms; correlations among first-order dimensions similarly define higher-order domains (e.g., internalizing or externalizing psychopathology). We hypothesize that the robust phenotypic correlations among first-order dimensions reflect a hierarchy of increasingly specific etiologic influences. Some nonspecific etiologic factors increase risk for all first-order dimensions of psychopathology to varying degrees through a general factor of psychopathology. Other nonspecific etiologic factors increase risk only for all first-order dimensions within a more specific higher-order domain. Furthermore, each first-order dimension has its own unique causal influences. Genetic and environmental influences common to family members tend to be nonspecific, whereas environmental influences unique to each individual are more dimension-specific. We posit that these causal influences on psychopathology are moderated by sex and developmental processes. This causal taxonomy also provides a novel framework for understanding the heterogeneity of each first-order dimension: Different persons exhibiting similar symptoms may be influenced by different combinations of etiologic influences from each of the 3 levels of the etiologic hierarchy. Furthermore, we relate the proposed causal taxonomy to transdimensional psychobiological processes, which also impact the heterogeneity of each psychopathology dimension. This causal taxonomy implies the need for changes in strategies for studying the etiology, psychobiology, prevention, and treatment of psychopathology. (PsycINFO Database Record

The University of British Columbia Twin Project: still figuring out what personality is and does

The University of British Columbia (UBC) Twin Project is a registry of approximately 2,000 pairs of reared-together twins recruited across the major Canadian provinces. The focus of the project is an investigation of the behavioral genetics of personality and its disorders, and their relationship to other forms of mental illness. The goal is to find evidence for current diagnostic structures and classification systems, or certainly provide data for their reform. The primary measures employed are full-form self-report questionnaires of major psychological and psychiatric instruments covering personality, mood, general health, schizotypy, and more recently the anxiety disorders from symptoms resulting from exposure traumatic events, obsessive-compulsive behavior and beliefs, as well as coping strategies and health anxieties. No DNA has been collected. Data from the project have been used in several collaborative projects worldwide, and collaborative projects with other groups and interested researchers are welcomed.

Processing of facial expressions of emotions in healthy volunteers: an exploration with event-related potentials and personality traits

AIMS OF THE STUDY

Previous studies have shown that event-related potentials (ERPs) are modulated by anxiety or psychopathic personality traits. Therefore, we hypothesized that the automatic processing of facial expressions of emotions (FEE) is also correlated with related disordered personality traits.

METHODS

Thirty-seven healthy volunteers underwent both an "oddball" ERP recording to facial expressions of Anger, Happiness, Sadness, and Neutral, and a test of the Dimensional Assessment of Personality Pathology (DAPP).

RESULTS

Mean reaction time was longer in response to anger than to other facial expressions. Facial expressions of Anger, Happiness and Sadness did not affect N1 (N170). By contrast, Happiness elicited a delayed P2, Anger elicited both a smaller N2 and a delayed P3b, and both Happiness and Anger elicited a P3b of higher amplitude. In addition, P3a latencies to Happiness were negatively correlated with DAPP Identity problems, and P3b latencies to Happiness were negatively correlated with DAPP Stimulus seeking, Callousness, Passive aggressivity, and Narcissism.

CONCLUSION

Our study demonstrates that Anger implicitly captures attentional resources, and Happiness triggers more facilitated processing in individuals with dissocial traits.

The Florida State Twin Registry: Research Aims and Design

Relatively little is known about the relationship of most personality disorders to executive cognitive functioning despite their associations with frontal cortex activity. Research on genetic influence is lacking for most personality disorders, and research on genetic influences associated with executive cognitive functioning is sparse and mixed. The Florida State Twin Registry was created to conduct a pilot twin study aimed at examining genetic influence on personality disorders and executive cognitive functioning. Measures included structured clinical interviews for symptoms and diagnoses of personality disorders (borderline, histrionic, narcissistic, antisocial, obsessive–compulsive, avoidant, and dependent), depression, substance abuse/dependence, anxiety disorders, and eating disorders. The Wisconsin Card Sorting Test and the Stroop Color-Word Test were administered to assess executive cognitive functioning. Self-report questionnaires were included to assess maladaptive personality traits. Data sharing and future directions for growing the Florida State Twin Registry are discussed.

A General Factor of Personality (GFP) in the Personality Disorders: Three Studies of the Dimensional Assessment of Personality Pathology — Basic Questionnaire (DAPP-BQ)

We used structural equation modeling to test the hypothesis that a General Factor of Personality (GFP) occupies the apex of the hierarchy of personality disorders in three validation samples of the Dimensional Assessment of Personality Pathology — Basic Questionnaire (DAPP-BQ). In a general population sample (N= 942), we found a GFP explained 34% of the variance in four first-order factors and 33% of the variance in all 18 scales. In a twin sample (N= 1,346), a GFP explained 35% of the variance in four first-order factors and 34% of the variance in all 18 scales. In a clinical sample (N= 656), a GFP explained 34% of the variance in four first-order factors and 30% of the variance in all 18 scales.

An empirically-based classification of personality disorder

An empirically-based classification is proposed based on studies of the phenotypic structure and genetic architecture of personality disorder. The proposed system has two parts: (1) a definition of general personality disorder, and (2) a system for diagnosing different forms of disorder. General personality disorder is conceptualized as a pervasive disturbance in the overall structure and organization of the personality system that is manifested as the failure to establish a coherent self-system and the capacity for adaptive interpersonal and social behavior. Different forms of disorder are represented by a dimensional system consisting of 30 primary traits organized into four higher-order domains. The system is intended to offer a systematic and comprehensive diagnosis of personality disorder for clinical and research purposes. It is also intended to be used in a flexible but prescribed way to provide a diagnostic assessment tailored to different assessment needs.

Borderline personality disorder traits and their relationship with dimensions of normative personality: a web-based cohort and twin study

OBJECTIVE

To describe the structure of genetic and environmental risk factors for four dimensions of borderline personality disorder (BPD) and to understand the source of resemblance of these dimensions and normal personality.

METHOD

A web-based sample (n = 44,112 including 542 twin pairs) completed items from 4 scales of the Dimensional Assessment of Personality Pathology Basic Questionnaire and the Big Five Inventory.

RESULTS

A one-factor common pathway model best fits the 4 BPD scales producing a highly heritable latent liability (heritability = 60%) and strong loadings on all 4 dimensions. Affective instability had the lowest trait-specific genetic loading, suggesting that it was a core feature of BPD. A complex pattern of genetic and environmental associations was found between the big five personality traits and BPD dimensions. The strongest genetic correlations with the BPD traits were generally seen for neuroticism (positive), followed by conscientiousness and agreeableness, both negative.

CONCLUSION

In the general population, these four BPD dimensions reflect one underlying highly heritable factor. The association between normative personality and dimensions of BPD is complex with high degrees of genetic correlation.

DSM-5 Borderline personality disorder: At the border between a dimensional and a categorical view

Recently, the DSM-5 Personality Disorders Workgroup offered its proposed revision for borderline personality disorder (BPD) and other personality disorder types ( http://www.dsm5.org ). According to the workgroup, this revision reflects an attempt to address excessive comorbidity among personality disorders, place personality pathology on continua, and replace individual behavioral criteria with personality traits. Essentially, the committee proposes a hybrid model of BPD (ie, categorical and dimensional)-one that combines the notion of a borderline "type" with supplemental dimensional ratings of relevant personality traits. In this article, we review recent findings on the dimensionality of BPD from phenotypic, genetic, and endophenotypic perspectives. Finally, we evaluate the current DSM-5 proposal for diagnosing BPD-one that ostensibly combines a categorical and dimensional perspective-in light of these findings.

A gene-environment investigation on personality traits in two independent clinical sets of adult patients with personality disorder and attention deficit/hyperactive disorder

While an interactive effect of genes with adverse life events is increasingly appreciated in current concepts of depression etiology, no data are presently available on interactions between genetic and environmental (G x E) factors with respect to personality and related disorders. The present study therefore aimed to detect main effects as well as interactions of serotonergic candidate genes (coding for the serotonin transporter, 5-HTT; the serotonin autoreceptor, HTR1A; and the enzyme which synthesizes serotonin in the brain, TPH2) with the burden of life events (#LE) in two independent samples consisting of 183 patients suffering from personality disorders and 123 patients suffering from adult attention deficit/hyperactivity disorder (aADHD). Simple analyses ignoring possible G x E interactions revealed no evidence for associations of either #LE or of the considered polymorphisms in 5-HTT and TPH2. Only the G allele of HTR1A rs6295 seemed to increase the risk of emotional-dramatic cluster B personality disorders (p = 0.019, in the personality disorder sample) and to decrease the risk of anxious-fearful cluster C personality disorders (p = 0.016, in the aADHD sample). We extended the initial simple model by taking a G x E interaction term into account, since this approach may better fit the data indicating that the effect of a gene is modified by stressful life events or, vice versa, that stressful life events only have an effect in the presence of a susceptibility genotype. By doing so, we observed nominal evidence for G x E effects as well as main effects of 5-HTT-LPR and the TPH2 SNP rs4570625 on the occurrence of personality disorders. Further replication studies, however, are necessary to validate the apparent complexity of G x E interactions in disorders of human personality.

The relationship between disturbed dreaming and somatic distress: a prospective investigation

Despite an abundant literature on disturbed dreaming (DD) incidence and psychopathology, little is known about the pathogenesis of these dream disturbances. Recent work strongly suggests that DD distress may be the primary determinant of the relationship between DD and waking psychological impairment. This is the first empirical investigation of the possible role of somatic distress as a crucial pathway in this relationship. A total of 313 college undergraduates completed 3 measures of somatic distress (SCL-90-R Somatization scale, Somatic Interpretations Questionnaire and the Anxiety Sensitivity Index) and then monitored their DD incidence and distress for 21 consecutive days. It was predicted that high levels of somatic distress would be associated with heightened levels of both DD incidence and distress. Although the results were somewhat mixed, individuals who reported more incidents of both bad dreams and nightmares did indeed report higher levels of somatic distress. The results were largely consistent with our predictions and the findings are discussed with regard to recent modeling by in identifying key cognitive diatheses for the development of DD.

Public health significance of neuroticism

The personality trait of neuroticism refers to relatively stable tendencies to respond with negative emotions to threat, frustration, or loss. Individuals in the population vary markedly on this trait, ranging from frequent and intense emotional reactions to minor challenges to little emotional reaction even in the face of significant difficulties. Although not widely appreciated, there is growing evidence that neuroticism is a psychological trait of profound public health significance. Neuroticism is a robust correlate and predictor of many different mental and physical disorders, comorbidity among them, and the frequency of mental and general health service use. Indeed, neuroticism apparently is a predictor of the quality and longevity of our lives. Achieving a full understanding of the nature and origins of neuroticism, and the mechanisms through which neuroticism is linked to mental and physical disorders, should be a top priority for research. Knowing why neuroticism predicts such a wide variety of seemingly diverse outcomes should lead to improved understanding of commonalities among those outcomes and improved strategies for preventing them.

Stability, change, and heritability of borderline personality disorder traits from adolescence to adulthood: a longitudinal twin study

Although personality disorders are best understood in the context of lifetime development, there is a paucity of work examining their longitudinal trajectory. An understanding of the expected course and the genetic and environmental contributions to these disorders is necessary for a detailed understanding of risk processes that lead to their manifestation. The current study examined the longitudinal course and heritability of borderline personality disorder (BPD) over a period of 10 years starting in adolescence (age 14) and ending in adulthood (age 24). In doing so, we built on existing research by using a large community sample of adolescent female twins, a sensitive dimensional measure of BPD traits, an extended follow-up period, and a longitudinal twin design that allowed us to investigate the heritability of BPD traits at four discrete ages spanning midadolescence to early adulthood. Results indicated that mean-level BPD traits significantly decline from adolescence to adulthood, but rank order stability remained high. BPD traits were moderately heritable at all ages, with a slight trend for increased heritability from age 14 to age 24. A genetically informed latent growth curve model indicated that both the stability and change of BPD traits are highly influenced by genetic factors and modestly by nonshared environmental factors. Our results indicate that as is the case for other personality dimensions, trait BPD declines as individuals mature from adolescence to adulthood, and that this process is influenced in part by the same genetic factors that influence BPD trait stability.

The structure of genetic and environmental risk factors for DSM-IV personality disorders: a multivariate twin study

CONTEXT

Although both genetic and environmental factors affect risk of individual personality disorders (PDs), we know little of how they contribute to the pattern of comorbidity between the PDs in the Diagnostic and Statistical Manual of Mental Disorders (Fourth Edition) (DSM-IV).

OBJECTIVE

To clarify the structure of the genetic and environmental risk factors for the 10 DSM-IV PDs.

DESIGN

Assessment of PDs at personal interview and multivariate twin modeling with the Mx program.

SETTING

General community.

PARTICIPANTS

A total of 2794 young adult members of the Norwegian Institute of Public Health Twin Panel. Main Outcome Measure Number of endorsed criteria for the 10 DSM-IV PDs.

RESULTS

The best-fit multivariate twin model required 3 genetic and 3 individual-specific environmental factors and genetic and individual-specific factors unique to each PD. The first genetic factor had high loadings on PDs from all 3 clusters including paranoid, histrionic, borderline, narcissistic, dependent, and obsessive-compulsive. The second genetic factor had substantial loadings only on borderline and antisocial PD. The third genetic factor had high loadings only on schizoid and avoidant PD. Several PDs had substantial disorder-specific genetic risk factors. The first, second, and third individual-specific environmental factors had high loadings on the cluster B, A, and C PDs, respectively, with 1 exception: obsessive-compulsive PD loaded with cluster B and not cluster C PDs.

CONCLUSIONS

Genetic risk factors for DSM-IV PDs do not reflect the cluster A, B, and C typology. Rather, 1 genetic factor reflects a broad vulnerability to PD pathology and/or negative emotionality. The 2 other genetic factors are more specific and reflect high impulsivity/low agreeableness and introversion. Unexpectedly, the cluster A, B, and C typology is well reflected in the structure of environmental risk factors, suggesting that environmental experiences may be responsible for the tendency of cluster A, B, and C PDs to co-occur.

A short form of the Dimensional Assessment of Personality Pathology-Basic Questionnaire (DAPP-BQ): the DAPP-SF

A short form of the Dimensional Assessment of Personality Pathology-Basic Questionnaire (DAPP-BQ), called the DAPP-SF, is presented, consisting of 136 of the original 290 items. It was established in a community sample that the factor structure of the DAPP-SF is highly congruent with the structure of the DAPP-BQ. The 18 DAPP-SF scales, which were found to be highly reliable, turned out to correlate substantially with the DAPP-BQ scales, even after applying a necessary correction, as the DAPP-SF was developed in the same sample used to investigate the Dutch DAPP-BQ. The higher-order convergent validity of the DAPP-SF was demonstrated by correlating the DAPP-SF scales and factors with Van Kampen's 5DPT. The same factor structure as found in the community sample of patients with personality disorder, also demonstrating that the agreement between the DAPP-SF and the DAPP-BQ is not dependent on the use of shared data. Finally, following Bagge and Trull [Bagge, C.L., Trull, T.J., 2003. DAPP-BQ: Factor structure and relations to personality disorder symptoms in a non-clinical sample. Journal of Personality Disorders 17, 19-32], specific predictions were tested concerning differences in means on the 18 scales between 10 diagnostic groups in the sample of patients with personality disorder. Results supported the validity of the DAPP-SF with respect to its lower-order structure. Finally, for practical purposes, preliminary norms are presented for females and males from the community in two different age groups.

The Behavioral Genetics of Personality Disorder

Behavioral genetics research has opened a new window on understanding personality disorder. The earliest studies were focused on establishing the relative contributions of genes and the environment in these disorders. Although these studies provided solid evidence of the importance of genetic and environmental influences on personality disorder and showed that all aspects of personality disorder are subject to genetic influence, heritability studies are limited because they are not helpful in explicating causal mechanisms. More recent research has focused on the relative contributions of the covariation of personality disorder diagnoses and traits, which allows one to examine etiological relationships. These developments are leading to major changes in ideas about what constitutes the environment and nature of the interplay between genes and environment. The present review examines major themes in this growing body of research in the context of current issues in the personality disorders.

Personality in relation to genetic liability for schizophrenia and bipolar disorder: differential associations with the COMT Val 108/158 Met polymorphism

Schizophrenia and bipolar disorder may share aspects of genetic etiology. Evidence supports the Val 108/158 Met polymorphism of the Catechol-o-Methyltransferase (COMT) gene as potentially contributing to the etiology of both disorders. To determine whether the COMT gene is associated with personality traits related to genetic risk for either schizophrenia or bipolar disorder, we examined dimensions of personality psychopathology in biological relatives of individuals with the disorders. Specifically, we contrasted personality characteristics of first-degree relatives of people with schizophrenia, first-degree relatives of people with bipolar-I disorder, and nonpsychiatric control participants using scores from the Dimensional Assessment of Personality Pathology-Brief Questionnaire (DAPP-BQ). We also characterized the COMT Val 108/158 Met polymorphism of subjects. Compared to controls, relatives of schizophrenia patients scored lower on stimulus seeking and higher on restrictive expression and social avoidance. Compared to relatives of bipolar patients, relatives of schizophrenia patients had lower scores on narcissism, rejectionality (i.e., rejection of ideas of others), stimulus seeking, passive-aggressive oppositionality, and self-harm. The subset of relatives of schizophrenia patients who were COMT val homozygotes exhibited lower scores on narcissism, rejectionality, and stimulus seeking than met homozygote relatives of schizophrenia patients and control participants. Although relatives of bipolar patients showed scale elevations consistent with emotional dysregulation, the scores failed to be associated with the Val 108/158 Met polymorphism. Abnormally low narcissism and rejectionality in val homozygote relatives of schizophrenia patients suggests that the val allele of the COMT polymorphism may be associated with an underdeveloped self-concept phenomenologically similar to made volition and passivity experiences comprising first-rank symptoms of schizophrenia.

Factor analysis of the Dutch-language version of the MCMI-III

We analyzed the factor structure of the Dutch-language version of the MCMI-III (Millon, Millon, Davis, & Grossman, 2006) using exploratory factor analysis on data obtained from a heterogeneous White sample (n = 1,210). We identified 4 factors: General Maladjustment, Aggression/Social Deviance, Paranoid/Delusional Thinking, and Emotional Instability/Detachment. This structure was invariant across scale composition (linear dependent vs. independent scales), factor analytic method (principal factor vs. principal component solutions), and sample characteristics (gender 'male-female' and setting 'clinical-forensic.' Studies that have used previous MCMI (Millon, 1969/1983b) versions have also found 4 similar factors, whereas studies that have used the American version of the MCMI-III have only found 3 factors. However, differences between the Dutch and American version were completely determined by factor analytic decisions. The factor structure of the MCMI-III appeared to be cross-culturally invariant.

Structure of borderline personality disorder symptoms in a nonclinical sample

Relations among symptoms of the Diagnostic and Statistical Manual of Mental Disorders, Text Revision (DSM-IV-TR; American Psychiatric Association, 2000) borderline personality disorder (BPD) assessed using semistructured clinical interviews were examined using exploratory principal components analysis in a sample of 82 college men and women who were symptomatic for BPD (30.4% of whom met criteria for a BPD diagnosis at threshold or subthreshold certainty level). A three-component solution was found and, as expected, the first component was characterized by interpersonal instability and included unstable relationships, identity disturbance, and chronic emptiness. The second component reflected affective instability and low impulsivity. The third component reflected stress-related paranoia and low anger. Results highlight similarities in the structure of BPD criteria in clinical and nonclinical samples, and could inform future research on dimensional models of BPD.

Cross-cultural studies of personality traits and their relevance to psychiatry

AIMS

This article provides a brief review of recent cross-cultural research on personality traits at both individual and culture levels, highlighting the relevance of recent findings for psychiatry.

METHOD

In most cultures around the world, personality traits can be clearly summarized by the five broad dimensions of the Five-Factor Model (FFM), which makes it feasible to compare cultures on personality and psychopathology.

RESULTS

Maturational patterns and sex differences in personality traits generally show cultural invariance, which generates the hypothesis that age of onset, clinical evolution, and sex differences in the prevalence of psychiatric disorders might follow similar universal patterns. The average personality profiles from 51 cultures show meaningful geographical distributions and associations with culture-level variables, but are clearly unrelated to national character stereotypes.

CONCLUSIONS

Aggregate personality scores can potentially be related to epidemiological data on psychiatric disorders, and dimensional personality models have implications for psychiatric diagnosis and treatment around the world.

COMT polymorphisms and anxiety-related personality traits

High neuroticism and low extraversion are characteristic of anxiety-prone individuals. A functional variant in the catechol-O-methyltransferase (COMT) gene, the Val158Met ('val/met') polymorphism, has been associated in some prior studies with several phenotypes, including neuroticism. We tested the hypothesis that the val158met polymorphism would be associated with both high neuroticism and low extraversion, making it a plausible candidate locus for anxiety susceptibility. To determine whether val158met is responsible for these effects, we also evaluated the association with haplotypes that included two other SNPs within the COMT gene. We collected a sample of 497 undergraduate college students who were phenotyped on a personality inventory (the NEO-Personality Inventory-Raised (NEO-PI-R)). Subjects were genotyped for three COMT polymorphisms: the well-studied nonsynonymous SNP rs4680 that generates a valine-to-methionine substitution (val158met), rs737865 (near exon #1), and rs165599 (also functional, near the 3'-UTR). Together, these three SNPs define a haplotype that is associated with reduced COMT expression in human brain. Logistic regression analyses were used to examine the effects of individual SNPs on extraversion and neuroticism scores. Score tests for association between these traits (quantitatively and dichotomously considered) and haplotypes were also conducted. We evaluated potential for population stratification artifact by genotyping a set of 36 unlinked highly polymorphic markers previously demonstrated to distinguish sufficiently ancestry of major American populations. Two of the SNPs (rs4680 ('val/met') and rs737865) were significantly associated with (low) extraversion and, less consistently, with (high) neuroticism, with effects confined to women. A significant association between COMT haplotype and (low) extraversion and (high) neuroticism was also observed. Formal testing showed that population structure did not explain the findings. These data suggest that involvement of the COMT locus in susceptibility to anxiety-related traits (ie low extraversion and high neuroticism) is unlikely to be wholly accounted for by the well-studied rs4680 ('val/met') polymorphism. Other functional variants may exist that contribute to this relationship. Possible sex-specific effects remain to be further studied and explained.

Delineating the structure of normal and abnormal personality: an integrative hierarchical approach

Increasing evidence indicates that normal and abnormal personality can be treated within a single structural framework. However, identification of a single integrated structure of normal and abnormal personality has remained elusive. Here, a constructive replication approach was used to delineate an integrative hierarchical account of the structure of normal and abnormal personality. This hierarchical structure, which integrates many Big Trait models proposed in the literature, replicated across a meta-analysis as well as an empirical study, and across samples of participants as well as measures. The proposed structure resembles previously suggested accounts of personality hierarchy and provides insight into the nature of personality hierarchy more generally. Potential directions for future research on personality and psychopathology are discussed.

Dimensional models of personality disorder: coverage and cutoffs

Two major challenges that must be addressed by dimensional models, if they are to be considered viable alternatives to the present categorical system for diagnosing personality disorders, involve the issues of coverage and cutoffs. Several dimensional models of personality and personality pathology are evaluated with these issues in mind. There is growing consensus for the relevance of at least four higher-order domains of personality functioning that are clearly related to personality pathology: neuroticism/negative affectivity/emotional dysregulation, extraversion/positive emotionality, dissocial/antagonistic behavior, and constraint/compulsivity/conscientiousness. A proposal for developing a dimensionally based diagnostic system for personality disorders incorporating these higher-order traits is offered.

Categorical and Dimensional Models of Personality Disorder

We review major categorical and dimensional models of personality pathology, highlighting advantages and disadvantages of these approaches. Several analytic and methodological approaches to the question of the categorical versus dimensional status of constructs are discussed, including taxometric analyses, latent class analyses, and multivariate genetic analyses. Based on our review, we advocate a dimensional approach to classifying personality pathology. There is converging evidence that four major domains of personality are relevant to personality pathology: neuroticism/negative affectivity/emotional dysregulation; extraversion/positive emotionality; dissocial/antagonistic behavior; and constraint/compulsivity/conscientiousness. Finally, we discuss how dimensional approaches might be integrated into the diagnostic system, as well as some of the major issues that must be addressed in order for dimensional approaches to gain wide acceptance.

Behavioral and molecular genetic contributions to a dimensional classification of personality disorder

This article examines the possible contribution of behavioral and molecular genetic research to the development of a dimensional classification of personality disorder. It is argued that the results of molecular studies are too preliminary to have immediate nosological significance. However, behavioral genetic methods could play a useful role in constructing a classification that reflects the genetic architecture of personality disorder. It is also argued that the best approach to constructing a valid classification would be to integrate behavioral genetic methods with the construct validation framework used in test construction. An integrative approach is proposed that seeks to combine constructs from alternative dimensional models. It is suggested that strong evidence of a four-dimensional structure to personality disorder provides a way to organize a preliminary model. An initial set of primary traits to define these secondary domains would then be compiled from existing models and refined using a combination of traditional psychometric analyses and behavioral genetic methods. It is concluded that an etiologically based classification is feasible for the DSM-V.

Delineating the structure of normal and abnormal personality: an integrative hierarchical approach

Increasing evidence indicates that normal and abnormal personality can be treated within a single structural framework. However, identification of a single integrated structure of normal and abnormal personality has remained elusive. Here, a constructive replication approach was used to delineate an integrative hierarchical account of the structure of normal and abnormal personality. This hierarchical structure, which integrates many Big Trait models proposed in the literature, replicated across a meta-analysis as well as an empirical study, and across samples of participants as well as measures. The proposed structure resembles previously suggested accounts of personality hierarchy and provides insight into the nature of personality hierarchy more generally. Potential directions for future research on personality and psychopathology are discussed.

A polymorphism of the beta1-adrenergic receptor is associated with low extraversion

BACKGROUND

We examined the possibility that allelic variation leading to alterations in beta(1)-adrenergic function might be present in persons with elevated social anxiety-related traits.

METHODS

A sample of 504 undergraduate college students were phenotyped on a personality inventory (the NEO-Personality Inventory-Revised) and measures of shyness and social anxiety and genotyped for two beta(1) adrenergic (ADRB1 gene) polymorphisms: a serine/glycine substitution at amino acid 49 (Ser49Gly) and an arginine/glycine substitution at residue 389 (Arg389Gly). We hypothesized that the Gly49 variant (thought to be functional), but not variation at Arg389Gly, would be associated with (low) extraversion and shyness. We evaluated the potential for population stratification artifact by genotyping a set of 36 unlinked, highly polymorphic markers previously demonstrated to sufficiently distinguish the ancestry of major American populations.

RESULTS

Presence of a Gly49 allele was associated with an increased odds of having low or very low extraversion (odds ratio = 1.68, 95% confidence interval 1.05-2.71). The Arg389Gly polymorphism, although in tight linkage disequilibrium (D' = -1.00) with Ser49Gly, was not significantly associated with level of extraversion. Formal testing showed that population structure did not explain the findings.

CONCLUSIONS

The Ser49Gly functional polymorphism in the beta(1) adrenergic receptor might explain some of the population variance in extraversion and related personality traits. Population structure was excluded as an explanation for these findings. We used a sufficient marker set to exclude possible population stratification artifact. These findings should be replicated and extended to the study of psychiatric disorders marked by low extraversion, namely social phobia and other phobic disorders.

Functioning styles of personality disorders and five-factor normal personality traits: a correlation study in Chinese students

BACKGROUND

Previous studies show that both the categorical and dimensional descriptors of personality disorders are correlated with normal personality traits. Recently, a 92-item inventory, the Parker Personality Measure (PERM) was designed as a more efficient and precise first-level assessment of personality disorders. Whether the PERM constructs are correlated with those of the five-factor models of personality needs to be clarified.

METHODS

We therefore invited 913 students from poly-technical schools and colleges in China to answer the PERM, the Five-Factor Nonverbal Personality Questionnaire (FFNPQ), and the Zuckerman-Kuhlman Personality Questionnaire (ZKPQ).

RESULTS

Most personality constructs had satisfactory internal alphas. PERM constructs were loaded with FFNPQ and ZKPQ traits clearly on four factors, which can be labelled as Dissocial, Emotional Dysregulation, Inhibition and Compulsivity, as reported previously. FFNPQ Openness to Experience, Conscientiousness and Extraversion formed another Factor, named Experience Hunting, which was not clearly covered by PERM or ZKPQ.

CONCLUSION

The PERM constructs were loaded in a predictable way on the disordered super-traits, suggesting the PERM might offer assistance measuring personality function in clinical practice.

Personality and psychopathology: working toward the bigger picture

There are systematic and meaningful links among normal and abnormal personality traits and Axis I and II constructs from the DSM. Nevertheless, much research in this area focuses on pairs of constructs (e.g., the link between personality traits and a specific Axis I disorder), rather than on the broader multivariate structure of the personality-psychopathology domain. We underscore the need for this broader perspective, a perspective that would transcend largely artificial boundaries between current constructs (e.g., normal and abnormal personality). We outline our approach to research from this perspective and we emphasize the internalizing (mood and anxiety) and externalizing (substance use and antisocial behavior) spectra as promising foci for initial research on the joint structure of personality and psychopathology.

Toward a molecular architecture of personality

Epidemiological studies provided a large body of evidence that personality dimensions are influenced by genetic factors and that the genetic component is highly complex, polygenic, and epistatic. However, consistent findings on the genetic basis of personality have yet remained sparse. In recent years, molecular genetics has begun to identify specific genes coding in particular for components of the serotonergic and dopaminergic neurotransmitter systems representing quantitative trait loci (QTLs) for behavioral traits. The QTL concept suggests that complex traits are not attributable to single genes. According to this polygenic model, the genetic basis of personality and behavior and its pathological variations thus results from additive or nonadditive interactions of various genes. As the number of suitable candidate genes constantly increases, the QTL model provides a reasonable explanation for the genetic basis of personality and its disorders. In this review, the current knowledge on the impact of a large number of candidate gene polymorphisms (e.g. variations in serotonin and dopamine receptor and serotonin transporter genes) on personality and temperament is summarized. Additionally, investigations of gene-gene and gene-environment interactions in humans and animals, which currently intensify the identification of genes that underlie behavioral variations, are examined. The findings converge on the notion that a probabilistic rather than deterministic impact of genes on the expression of behavior will contribute to the demystification of behavioral disorders.

The DAPP-BQ in The Netherlands: factor structure and relationship with basic personality dimensions

After discarding eight items in the Dutch translation of Livesley's DAPP-BQ that showed item-total correlations < 0.20 in a sample of 223 normal subjects. Cronbach's alpha coefficients were calculated for the remaining items in the 18 scales of this instrument. The 'Dutch' alpha coefficients proved to be satisfactory. Furthermore, the Dutch DAPP-BQ scales were factor analyzed, retaining four factors. Three of these factors proved to be identical (Emotional Dysregulation and Dissocial) or nearly identical (Compulsivity) to the Canadian factors. However, the original factor Inhibition was not the same as the remaining Dutch factor Intimacy Problems. In a sample of 115 students, the estimated scores for the Dutch Dimensional Assessment of Personality Pathology-Basic Questionnaire (DAPP-BQ) factors were correlated with the scales of Van Kampen's Four-Dimensional Personality Test. As expected, Emotional Dysregulation was found to correlate with Neuroticism, Dissocial with Insensitivity, and Compulsivity with Orderliness. The Intimacy Problems factor proved to be negatively correlated with Extraversion. The results obtained are embedded in the context of the evidence favoring a dimensional model of personality disorder. Furthermore, Livesley's proposal that separate diagnostic criteria for the existence of a personality disorder must be formulated to supplement the assessment by means of the DAPP-BQ is critically discussed.

Heritability of social anxiety-related concerns and personality characteristics: a twin study

Negative evaluation fears figure prominently in the cognitive psychology of patients with social phobia. In this study, we examine the heritability of negative evaluation fears by using a twin sample. The authors also examine the relationships between negative evaluation fears and personality dimensions relevant to social phobia. Scores on the brief version of the Fear of Negative Evaluation Scale (BFNE) were examined in a sample of 437 (245 monozygotic and 192 dizygotic) twin pairs. Biometrical model fitting was conducted by using standard statistical methods. Genetic and environmental correlations with personality dimensions (from the Dimensional Assessment of Personality Pathology-Basic Questionnaire) were also calculated. Broad heritability estimate of the BFNE was 48%. Additive genetic effects and unique environmental effects emerged as the primary influences on negative evaluation fears. Genetic correlations between BFNE scores and the submissiveness, anxiousness, and social avoidance facets of the Dimensional Assessment of Personality Pathology-Basic Questionnaire were high (r(g) =.78 to.80). A cognitive dimension central to the phenomenology (and, perhaps, cause) of social phobia, the fear of being negatively evaluated, is moderately heritable. Moreover, the same genes that influence negative evaluation fears appear to influence a cluster of anxiety-related personality characteristics. Implications and limitations of these findings are discussed.

Psychometric Properties of the Spanish Version of the BSI

Summary: This study investigates in a nonclinical sample some aspects of the reliability and validity of the Spanish adaptation of the Brief Symptom Inventory (BSI) as well as the relationship of personality dimensions and psychopathological symptoms. Factor analysis showed a six-factor structure: depression, phobic anxiety, paranoid ideation, obsession-compulsion, somatization, and hostility/aggressivity. Alpha reliabilities for the six BSI scales showed optimal indices (between 0.70 and 0.91). Furthermore, the relationships among BSI-extracted factors and extraversion (E), neuroticism (N), and psychoticism (P) scales of the EPQ-R were also studied. Phobic anxiety and somatization were related to N and P; hostility/aggressivity was related to N, P and E; obsession-compulsion was related to N, P and inversely to E. In conclusion, the Spanish version of the BSI is a reliable, valid, and rapid tool for the assessment of symptoms of depression, phobic anxiety, paranoid ideation, obsession-compulsion, somatization, and hostility/aggressivity in the nonclinical population.

Behavioural-genetic perspectives on personality function

In the wake of the recent announcements that the human genome has been mapped, efforts to identify the genetic loci underlying personality function will grow and intensify. Much research has already been done in this area, but it has for the most part been limited to classical biometrical approaches designed to determine if personality has a heritable basis. These so-called "heritability" studies estimate how much of the individual differences in personality are attributable to genetic differences among people. Molecular-genetic approaches, on the other hand, are designed to identify specific putative loci, but have yielded mixed results. The inconsistency in research findings can be attributed in part to the lack of sufficient numbers of genetic markers in the chromosomal regions of interest--a problem that the creation of a map of the human genome will help to rectify. This map and its inevitable refinements, however, can only advance the search for the genes for personality to a limited degree. Serious unresolved problems in the conceptualization and definition of personality and its dysfunction remain, which will hamper the search for personality genes.