Associations between birth size and later height from infancy through adulthood: An individual based pooled analysis of 28 twin cohorts participating in the CODATwins project

BACKGROUND

There is evidence that birth size is positively associated with height in later life, but it remains unclear whether this is explained by genetic factors or the intrauterine environment.

AIM

To analyze the associations of birth weight, length and ponderal index with height from infancy through adulthood within mono- and dizygotic twin pairs, which provides insights into the role of genetic and environmental individual-specific factors.

METHODS

This study is based on the data from 28 twin cohorts in 17 countries. The pooled data included 41,852 complete twin pairs (55% monozygotic and 45% same-sex dizygotic) with information on birth weight and a total of 112,409 paired height measurements at ages ranging from 1 to 69 years. Birth length was available for 19,881 complete twin pairs, with a total of 72,692 paired height measurements. The association between birth size and later height was analyzed at both the individual and within-pair level by linear regression analyses.

RESULTS

Within twin pairs, regression coefficients showed that a 1-kg increase in birth weight and a 1-cm increase in birth length were associated with 1.14-4.25 cm and 0.18-0.90 cm taller height, respectively. The magnitude of the associations was generally greater within dizygotic than within monozygotic twin pairs, and this difference between zygosities was more pronounced for birth length.

CONCLUSION

Both genetic and individual-specific environmental factors play a role in the association between birth size and later height from infancy to adulthood, with a larger role for genetics in the association with birth length than with birth weight.

Psychoneurometric assessment of dispositional liabilities for suicidal behavior: phenotypic and etiological associations

BACKGROUND

Can core genetic liabilities for suicidal behavior be indexed using psychological and neural indicators combined? The current work addressed this question by examining phenotypic and genetic associations of two biobehavioral traits, threat sensitivity (THT) and disinhibition (DIS) - operationalized as psychoneurometric variables (i.e., composites of psychological-scale and neurophysiological measures) - with suicidal behaviors in a sample of adult twins.

METHODS

Participants were 444 identical and fraternal twins recruited from an urban community. THT was assessed using a psychological-scale measure of fear/fearlessness combined with physiological indicators of reactivity to aversive pictures, and DIS was assessed using scale measures of disinhibitory tendencies combined with indicators of brain response from lab performance tasks. Suicidality was assessed using items from structured interview and questionnaire protocols.

RESULTS

THT and DIS each contributed uniquely to prediction of suicidality when assessed psychoneurometrically (i.e., as composites of scale and neurophysiological indicators). In addition, these traits predicted suicidality interactively, with participants high on both reporting the greatest degree of suicidal behaviors. Biometric (twin-modeling) analyses revealed that a high percentage of the predictive association for each psychoneurometric trait (83% for THT, 68% for DIS) was attributable to genetic variance in common with suicidality.

CONCLUSIONS

Findings indicate that psychoneurometric assessments of biobehavioral traits index genetic liability for suicidal behavior, and as such, can serve as innovative targets for research on core biological processes contributing to severe psychopathology, including suicidal proclivities and actions.

Do DSM-5 Section II personality disorders and Section III personality trait domains reflect the same genetic and environmental risk factors?

BACKGROUND

DSM-5 includes two conceptualizations of personality disorders (PDs). The classification in Section II is identical to the one found in DSM-IV, and includes 10 categorical PDs. The Alternative Model (Section III) includes criteria for dimensional measures of maladaptive personality traits organized into five domains. The degree to which the two conceptualizations reflect the same etiological factors is not known.

METHODS

We use data from a large population-based sample of adult twins from the Norwegian Institute of Public Health Twin Panel on interview-based DSM-IV PDs and a short self-report inventory that indexes the five domains of the DSM-5 Alternative Model plus a domain explicitly targeting compulsivity. Schizotypal, Paranoid, Antisocial, Borderline, Avoidant, and Obsessive-compulsive PDs were assessed at the same time as the maladaptive personality traits and 10 years previously. Schizoid, Histrionic, Narcissistic, and Dependent PDs were only assessed at the first interview. Biometric models were used to estimate overlap in genetic and environmental risk factors.

RESULTS

When measured concurrently, there was 100% genetic overlap between the maladaptive trait domains and Paranoid, Schizotypal, Antisocial, Borderline, and Avoidant PDs. For OCPD, 43% of the genetic variance was shared with the domains. Genetic correlations between the individual domains and PDs ranged from +0.21 to +0.91.

CONCLUSION

The pathological personality trait domains, which are part of the Alternative Model for classification of PDs in DSM-5 Section III, appears to tap, at an aggregate level, the same genetic risk factors as the DSM-5 Section II classification for most of the PDs.

Deriving ICD-11 personality disorder domains from dsm-5 traits: initial attempt to harmonize two diagnostic systems

OBJECTIVE

The personality disorder domains proposed for the ICD-11 comprise Negative Affectivity, Detachment, Dissociality, Disinhibition, and Anankastia, which are reasonably concordant with the higher-order trait domains in the Alternative DSM-5 Model for Personality Disorders.

METHOD

We examined (i) whether designated DSM-5 trait facets can be used to describe the proposed ICD-11 trait domains, and (ii) how these ICD-11 trait features are hierarchically organized. A mixed Danish derivation sample (N = 1541) of 615 psychiatric out-patients and 925 community participants along with a US replication sample (N = 637) completed the Personality Inventory for DSM-5 (PID-5). Sixteen PID-5 traits were designated to cover features of the ICD-11 trait domains.

RESULTS

Exploratory structural equation modeling (ESEM) analyzes showed that the designated traits were meaningfully organized in the proposed ICD-11 five-domain structure as well as other recognizable higher-order models of personality and psychopathology. Model fits revealed that the five proposed ICD-11 personality disorder domains were satisfactorily resembled, and replicated in the independent US sample.

CONCLUSION

The proposed ICD-11 personality disorder domains can be accurately described using designated traits from the DSM-5 personality trait system. A scoring algorithm for the ICD-11 personality disorder domains is provided in appendix.

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.

The structure of adolescent psychopathology: a symptom-level analysis

BACKGROUND

Most empirical studies into the covariance structure of psychopathology have been confined to adults. This work is not developmentally informed as the meaning, age-of-onset, persistence and expression of disorders differ across the lifespan. This study investigates the underlying structure of adolescent psychopathology and associations between the psychopathological dimensions and sex and personality risk profiles for substance misuse and mental health problems.

METHOD

This study analyzed data from 2175 adolescents aged 13.3 years. Five dimensional models were tested using confirmatory factor analysis and the external validity was examined using a multiple-indicators multiple-causes model.

RESULTS

A modified bifactor model, with three correlated specific factors (internalizing, externalizing, thought disorder) and one general psychopathology factor, provided the best fit to the data. Females reported higher mean levels of internalizing, and males reported higher mean levels of externalizing. No significant sex differences emerged in liability to thought disorder or general psychopathology. Liability to internalizing, externalizing, thought disorder and general psychopathology was characterized by a number of differences in personality profiles.

CONCLUSIONS

This study is the first to identify a bifactor model including a specific thought disorder factor. The findings highlight the utility of transdiagnostic treatment approaches and the importance of restructuring psychopathology in an empirically based manner.

Personality disorder in DSM-5: an oral history

As the revision process leading to DSM-5 began, the domain of personality disorder embodied the highest aspirations for major change. After an initial prototype-based proposal failed to gain acceptance, the Personality and Personality Disorders Work Group (P&PDWG) developed a hybrid model containing categorical and dimensional components. A clash of perspectives both within the P&PDWG and between the P&PDWG and DSM-5 oversight committees led to the rejection of this proposal from the main body of DSM-5. Major issues included conflicting ways of conceptualizing validation, differences of opinion from personality disorder experts outside the P&PDWG, divergent concepts of the magnitude of evidence needed to support substantial changes, and the disagreements about clinical utility of the hybrid model. Despite these setbacks, the 'Alternative DSM-5 Model of Personality Disorder' is presented in Section III of the DSM-5. Further research should clarify its performance relative to the DSM-IV criteria reprinted in the main DSM-5 text.

A longitudinal twin study of borderline and antisocial personality disorder traits in early to middle adulthood

BACKGROUND

Antisocial personality disorder (ASPD) and borderline personality disorder (BPD) share genetic and environmental risk factors. Little is known about the temporal stability of these etiological factors in adulthood.

METHOD

DSM-IV criteria for ASPD and BPD were assessed using structured interviews in 2282 Norwegian twins in early adulthood and again approximately 10 years later. Longitudinal biometric models were used to analyze the number of endorsed criteria.

RESULTS

The mean criterion count for ASPD and BPD decreased 40% and 28%, respectively, from early to middle adulthood. Rank-order stability was 0.58 for ASPD and 0.45 for BPD. The best-fitting longitudinal twin model included only genetic and individual-specific environmental factors. Genetic effects, both those shared by ASPD and BPD, and those specific to each disorder remained completely stable. The unique environmental effects, however, changed substantially, with a correlation across time of 0.19 for the shared effects, and 0.39 and 0.15, respectively, for those specific to ASPD and BPD. Genetic effects accounted for 71% and 72% of the stability over time for ASPD and BPD, respectively. The genetic and environmental correlations between ASPD and BPD were 0.73, and 0.43, respectively, at both time points.

CONCLUSION

ASPD and BPD traits were moderately stable from early to middle adulthood, mostly due to genetic risk factors which did not change over the 10-year assessment period. Environmental risk factors were mostly transient, and appear to be the main source of phenotypic change. Genetic liability factors were, to a large extent, shared by ASPD and BPD.

A longitudinal twin study of cluster A personality disorders

BACKGROUND

While cluster A personality disorders (PDs) have been shown to be moderately heritable, we know little about the temporal stability of these genetic risk factors.

METHOD

Paranoid PD (PPD) and schizotypal PD (STPD) were assessed using the Structured Interview for DSM-IV Personality in 2793 young adult twins from the Norwegian Institute of Public Health Twin Panel at wave 1 and 2282 twins on average 10 years later at wave 2. Using the program Mx, we fitted a longitudinal latent factor model using the number of endorsed criteria for PPD and STPD.

RESULTS

The stability over time of the criteria counts for PPD and STPD, estimated as polychoric correlations, were +0.34 and +0.40, respectively. The best-fit longitudinal model included only additive genetic and individual-specific environmental factors with parameter estimates constrained to equality across the two waves. The cross-wave genetic and individual-specific environmental correlations for a latent cluster A factor were estimated to equal +1.00 and +0.13, respectively. The cross-time correlations for genetic and environmental effects specific to the individual PDs were estimated at +1.00 and +0.16-0.20, respectively. We found that 68% and 71% of the temporal stability of PPD and STPD derived, respectively, from the effect of genetic factors.

CONCLUSION

Shared genetic risk factors for two of the cluster A PDs are highly stable in adults over a 10-year period while environmental risk factors are relatively transient. Over two-thirds of the long-term stability of the common cluster A PD liability can be attributed to genetic influences.

Examining the shared and unique relationships among substance use and mental disorders

BACKGROUND

Co-morbidity among use of different substances can be explained by a shared underlying dimensional factor. What remains unknown is whether the relationship between substance use and various co-morbid mental disorders can be explained solely by the general factor or whether there remain unique contributions of specific substances.

METHOD

Data were from the 2007 Australian National Survey of Mental Health and Wellbeing (NSMHWB). A unidimensional latent factor was constructed that represented general substance use. The shared and specific relationships between lifetime substance use indicators and internalizing disorders, suicidality and psychotic-like experiences (PLEs) were examined using Multiple Indicators Multiple Causes (MIMIC) models in the total sample. Additional analyses then examined the shared and specific relationships associated with substance dependence diagnoses as indicators of the latent trait focusing on a subsample of substance users.

RESULTS

General levels of latent substance use were significantly and positively related to internalizing disorders, suicidality and psychotic-like experiences. Similar results were found when examining general levels of latent substance dependence in a sample of substance users. There were several direct effects between specific substance use/dependence indicators and the mental health correlates that significantly improved the overall model fit but they were small in magnitude and had relatively little impact on the general relationship.

CONCLUSIONS

The majority of pairwise co-morbid relationships between substance use/dependence and mental health correlates can be explained through a general latent factor. Researchers should focus on investigating the commonalities across all substance use and dependence indicators when studying mental health co-morbidity.

Modeling and treating internalizing psychopathology in a clinical trial: a latent variable structural equation modeling approach

BACKGROUND

Clinical trials are typically designed to test the effect of a specific treatment on a single diagnostic entity. However, because common internalizing disorders are highly correlated ('co-morbid'), we sought to establish a practical and parsimonious method to characterize and quantify changes in a broad spectrum of internalizing psychopathology targeted for treatment in a clinical trial contrasting two transdiagnostic psychosocial interventions.

METHOD

Alcohol dependence treatment patients who had any of several common internalizing disorders were randomized to a six-session cognitive-behavioral therapy (CBT) experimental treatment condition or a progressive muscle relaxation training (PMRT) comparison treatment condition. Internalizing psychopathology was characterized at baseline and 4 months following treatment in terms of the latent structure of six distinct internalizing symptom domain surveys.

RESULTS

Exploratory structural equation modeling (ESEM) identified a two-factor solution at both baseline and the 4-month follow-up: Distress (measures of depression, trait anxiety and worry) and Fear (measures of panic anxiety, social anxiety and agoraphobia). Although confirmatory factor analysis (CFA) demonstrated measurement invariance between the time-points, structural models showed that the latent means of Fear and Distress decreased substantially from baseline to follow-up for both groups, with a small but statistically significant advantage for the CBT group in terms of Distress (but not Fear) reduction.

CONCLUSIONS

The approach demonstrated in this study provides a practical solution to modeling co-morbidity in a clinical trial and is consistent with converging evidence pointing to the dimensional structure of internalizing psychopathology.

Thought disorder in the meta-structure of psychopathology

BACKGROUND

Dimensional models of co-morbidity have the potential to improve the conceptualization of mental disorders in research and clinical work, yet little is known about how relatively uncommon disorders may fit with more common disorders. The present study estimated the meta-structure of psychopathology in the US general population focusing on the placement of five under-studied disorders sharing features of thought disorder: paranoid, schizoid, avoidant and schizotypal personality disorders, and manic episodes as well as bipolar disorder.

METHOD

Data were drawn from the National Epidemiologic Survey on Alcohol and Related Conditions, a face-to-face interview of 34 653 non-institutionalized adults in the US general population. The meta-structure of 16 DSM-IV Axis I and Axis II psychiatric disorders, as assessed by the Alcohol Use Disorder and Associated Disabilities Interview Schedule DSM-IV version (AUDADIS-IV), was examined using exploratory and confirmatory factor analysis.

RESULTS

We document an empirically derived thought disorder factor that is a subdomain of the internalizing dimension, characterized by schizoid, paranoid, schizotypal and avoidant personality disorders as well as manic episodes. Manic episodes exhibit notable associations with both the distress subdomain of the internalizing dimension as well as the thought disorder subdomain. The structure was replicated for bipolar disorder (I or II) in place of manic episodes.

CONCLUSIONS

As our understanding of psychopathological meta-structure expands, incorporation of disorders characterized by detachment and psychoticism grows increasingly important. Disorders characterized by detachment and psychoticism may be well conceptualized, organized and measured as a subdimension of the internalizing spectrum of disorders. Manic episodes and bipolar disorder exhibit substantial co-morbidity across both distress and thought disorder domains of the internalizing dimension. Clinically, these results underscore the potential utility of conceptualizing patient treatment needs using an approach targeting psychopathological systems underlying meta-structural classification rubrics.

Initial construction of a maladaptive personality trait model and inventory for DSM-5

BACKGROUND

DSM-IV-TR suggests that clinicians should assess clinically relevant personality traits that do not necessarily constitute a formal personality disorder (PD), and should note these traits on Axis II, but DSM-IV-TR does not provide a trait model to guide the clinician. Our goal was to provide a provisional trait model and a preliminary corresponding assessment instrument, in our roles as members of the DSM-5 Personality and Personality Disorders Workgroup and workgroup advisors.

METHOD

An initial list of specific traits and domains (broader groups of traits) was derived from DSM-5 literature reviews and workgroup deliberations, with a focus on capturing maladaptive personality characteristics deemed clinically salient, including those related to the criteria for DSM-IV-TR PDs. The model and instrument were then developed iteratively using data from community samples of treatment-seeking participants. The analytic approach relied on tools of modern psychometrics (e.g. item response theory models).

RESULTS

A total of 25 reliably measured core elements of personality description emerged that, together, delineate five broad domains of maladaptive personality variation: negative affect, detachment, antagonism, disinhibition, and psychoticism.

CONCLUSIONS

We developed a maladaptive personality trait model and corresponding instrument as a step on the path toward helping users of DSM-5 assess traits that may or may not constitute a formal PD. The inventory we developed is reprinted in its entirety in the Supplementary online material, with the goal of encouraging additional refinement and development by other investigators prior to the finalization of DSM-5. Continuing discussion should focus on various options for integrating personality traits into DSM-5.

Delineating physiologic defensive reactivity in the domain of self-report: phenotypic and etiologic structure of dispositional fear

BACKGROUND

Individual differences in fear and fearlessness have been investigated at their extremes in relation to markedly different forms of psychopathology--anxiety disorders and psychopathy, respectively. A documented neural substrate of fear-related traits and disorders is defensive reactivity as reflected in aversive startle potentiation (ASP).

METHOD

The current study extended prior work by characterizing, in a sample of adult twins from the community (n = 2511), the phenotypic and etiologic structure of self-report measures of fear and fearlessness known to be associated with ASP.

RESULTS

Analyses revealed a hierarchical structure to the trait fear domain, with an overarching, bipolar fear/fearlessness dimension saturating each measure in this domain, and subfactors labeled 'distress,' 'stimulation seeking' and 'sociability' accounting for additional variance in particular measures. The structure of genetic and non-shared environmental associations among the measures closely mirrored the phenotypic structure of the domain.

CONCLUSIONS

The findings have implications for proposals to reconceptualize psychopathology in neurobiological terms.

The structure of depression, anxiety and somatic symptoms in primary care

BACKGROUND

Observed co-morbidity among the mood and anxiety disorders has led to the development of increasingly sophisticated dimensional models to represent the common and unique features of these disorders. Patients often present to primary care settings with a complex mixture of anxiety, depression and somatic symptoms. However, relatively little is known about how somatic symptoms fit into existing dimensional models.

METHOD

We examined the structure of 91 anxiety, depression and somatic symptoms in a sample of 5433 primary care patients drawn from 14 countries. One-, two- and three-factor lower-order models were considered; higher-order and hierarchical variants were studied for the best-fitting lower-order model.

RESULTS

A hierarchical, bifactor model with all symptoms loading simultaneously on a general factor, along with one of three specific anxiety, depression and somatic factors, was the best-fitting model. The general factor accounted for the bulk of symptom variance and was associated with psychosocial dysfunction. Specific depression and somatic symptom factors accounted for meaningful incremental variance in diagnosis and dysfunction, whereas anxiety variance was associated primarily with the general factor.

CONCLUSIONS

The results (a) are consistent with previous studies showing the presence and importance of a broad internalizing or distress factor linking diverse emotional disorders, and (b) extend the bounds of internalizing to include somatic complaints with non-physical etiologies.

Meta-analysis of genome-wide association studies identifies common variants in CTNNA2 associated with excitement-seeking

The tendency to seek stimulating activities and intense sensations define excitement-seeking, a personality trait akin to some aspects of sensation-seeking. This trait is a central feature of extraversion and is a component of the multifaceted impulsivity construct. Those who score high on measures of excitement-seeking are more likely to smoke, use other drugs, gamble, drive recklessly, have unsafe/unprotected sex and engage in other risky behaviors of clinical and social relevance. To identify common genetic variants associated with the Excitement-Seeking scale of the Revised NEO Personality Inventory, we performed genome-wide association studies in six samples of European ancestry (N=7860), and combined the results in a meta-analysis. We identified a genome-wide significant association between the Excitement-Seeking scale and rs7600563 (P=2 × 10(-8)). This single-nucleotide polymorphism maps within the catenin cadherin-associated protein, alpha 2 (CTNNA2) gene, which encodes for a brain-expressed α-catenin critical for synaptic contact. The effect of rs7600563 was in the same direction in all six samples, but did not replicate in additional samples (N=5105). The results provide insight into the genetics of excitement-seeking and risk-taking, and are relevant to hyperactivity, substance use, antisocial and bipolar disorders.

Genome-wide association study of conduct disorder symptomatology

Conduct disorder (CD) is one of the most prevalent childhood psychiatric conditions, and is associated with a number of serious concomitant and future problems. CD symptomatology is known to have a considerable genetic component, with heritability estimates in the range of 50%. Despite this, there is a relative paucity of studies aimed at identifying genes involved in the susceptibility to CD. In this study, we report results from a genome-wide association study of CD symptoms. CD symptoms were retrospectively reported by a psychiatric interview among a sample of cases and controls, in which cases met the criteria for alcohol dependence. Our primary phenotype was the natural log transformation of the number of CD symptoms that were endorsed, with data available for 3963 individuals who were genotyped on the Illumina Human 1M beadchip array. Secondary analyses are presented for case versus control status, in which caseness was established as endorsing three or more CD symptoms (N = 872 with CD and N = 3091 without CD). We find four markers that meet the criteria for genome-wide significance (P<5 × 10(-8)) with the CD symptom count, two of which are located in the gene C1QTNF7 (C1q and tumor necrosis factor-related protein 7). There were six additional SNPs in the gene that yielded converging evidence of association. These data provide the first evidence of a specific gene that is associated with CD symptomatology. None of the top signals resided in traditional candidate genes, underscoring the importance of a genome-wide approach for identifying novel variants involved in this serious childhood disorder.

Contrasting prototypes and dimensions in the classification of personality pathology: evidence that dimensions, but not prototypes, are robust

BACKGROUND

DSM-5 may mark the shift from a categorical classification of personality pathology to a dimensional system. Although dimensional and categorical conceptualizations of personality pathology are often viewed as competing, it is possible to develop categories (prototypes) from combinations of dimensions. Robust prototypes could bridge dimensions and categories within a single classification system.

METHOD

To explore prototype structure and robustness, we used finite mixture modeling to identify empirically derived personality pathology prototypes within a large sample (n=8690) of individuals from four settings (clinical, college, community, and military), assessed using a dimensional measure of normal and abnormal personality traits, the Schedule for Nonadaptive and Adaptive Personality (SNAP). We then examined patterns of convergent and discriminant external validity for prototypes. Finally, we investigated the robustness of the dimensional structure of personality pathology.

RESULTS

The resulting prototypes were meaningful (externally valid) but non-robust (sample dependent). By contrast, factor analysis revealed that the dimensional structures underlying specific traits were highly robust across samples.

CONCLUSIONS

We interpret these results as further evidence of the fundamentally dimensional nature of an empirically based classification of personality pathology.

Borderline personality disorder co-morbidity: relationship to the internalizing-externalizing structure of common mental disorders

BACKGROUND

Borderline personality disorder (BPD) shows high levels of co-morbidity with an array of psychiatric disorders. The meaning and causes of this co-morbidity are not fully understood. Our objective was to investigate and clarify the complex co-morbidity of BPD by integrating it into the structure of common mental disorders.

METHOD

We conducted exploratory and confirmatory factor analyses on diagnostic interview data from a representative US population-based sample of 34 653 civilian, non-institutionalized individuals aged ≥18 years. We modeled the structure of lifetime DSM-IV diagnoses of BPD and antisocial personality disorder (ASPD), major depressive disorder, dysthymic disorder, panic disorder with agoraphobia, social phobia, specific phobia, generalized anxiety disorder, post-traumatic stress disorder, alcohol dependence, nicotine dependence, marijuana dependence, and any other drug dependence.

RESULTS

In both women and men, the internalizing-externalizing structure of common mental disorders captured the co-morbidity among all disorders including BPD. Although BPD was unidimensional in terms of its symptoms, BPD as a disorder showed associations with both the distress subfactor of the internalizing dimension and the externalizing dimension.

CONCLUSIONS

The complex patterns of co-morbidity observed with BPD represent connections to other disorders at the level of latent internalizing and externalizing dimensions. BPD is meaningfully connected with liabilities shared with common mental disorders, and these liability dimensions provide a beneficial focus for understanding the co-morbidity, etiology and treatment of BPD.

Alcohol craving and the dimensionality of alcohol disorders

BACKGROUND

ICD-10 includes a craving criterion for alcohol dependence while DSM-IV does not. Little is known about whether craving fits with or improves the DSM-IV criteria set for alcohol-use disorders.

METHOD

Data were derived from current drinkers (n=18 352) in the 1991-1992 National Longitudinal Alcohol Epidemiologic Survey (NLAES), a nationally representative survey of US adults >17 years of age. The Alcohol Use Disorder and Associated Disabilities Interview Schedule was used to assess the eleven DSM-IV dependence and abuse criteria, and alcohol craving. Exploratory factor, item response theory, and regression analyses were used to evaluate the psychometric properties and concurrent validity of DSM-based alcohol disorder criteria with the addition of alcohol craving.

RESULTS

The past 12-month prevalence of craving was 1.3%. Craving formed part of a unidimensional latent variable that included existing DSM-IV criteria. Craving demonstrated high severity on the alcohol-use disorder continuum, resulting in an improved dimensional model with greater discriminatory ability compared with current DSM-IV criteria. Correlates of the diagnosis did not change with the addition of craving, and past 12-month craving was associated with prior alcohol dependence, depression, and earlier age of alcohol disorder onset among those with current DSM-IV alcohol dependence.

CONCLUSIONS

The addition of craving to the existing DSM-IV criteria yields a continuous measure that better differentiates individuals with and without alcohol problems along the alcohol-use disorder continuum. Few individuals are newly diagnosed with alcohol dependence given the addition of craving, indicating construct validity but redundancy with existing criteria.

Genetic and environmental influences on internalizing psychopathology vary as a function of economic status

BACKGROUND

Different theories of the link between socio-economic status (SES) and mental illness have been postulated. In particular, two theories of this association, social causation and social selection, differ in the implied causal pathway. The authors employ behavior genetic modeling to consider evidence for both social selection and social causation in the relationship between income variation and internalizing disorders.

METHOD

Behavior genetic modeling was used to estimate the presence of gene-environment interaction (GxE, social causation) in the presence of gene-environment correlation (rGE, social selection). Participants were members of a sample of 719 twin pairs from the Midlife in the United States study. Four internalizing (INT) syndromes were assessed: major depression (MD); generalized anxiety disorder (GAD); panic attacks (PA); neuroticism (N). SES was measured with total family household income.

RESULTS

One factor best accounted for the variance shared between MD, GAD, PA and N. The etiology of variation in INT changed from high to low levels of income, with unique environmental factors playing a larger role in INT variation at lower levels of income. Across levels of income, rGE between income and INT was modest (low income ra=0.39 to high income ra=0.54), implying a selection process operating through genetic effects linking lower income with INT psychopathology.

CONCLUSIONS

Findings support social causation by suggesting that low income contributes significantly to environmental variation in INT. Modest support was found for social selection, but should be extended using longitudinal designs. Effective interventions for internalizing psychopathology may differ depending on income.

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.

Externalizing disorders: cluster 5 of the proposed meta-structure for DSM-V and ICD-11

BACKGROUND

The extant major psychiatric classifications DSM-IV and ICD-10 are purportedly atheoretical and largely descriptive. Although this achieves good reliability, the validity of a medical diagnosis is greatly enhanced by an understanding of the etiology. In an attempt to group mental disorders on the basis of etiology, five clusters have been proposed. We consider the validity of the fifth cluster, externalizing disorders, within this proposal.

METHOD

We reviewed the literature in relation to 11 validating criteria proposed by the Study Group of the DSM-V Task Force, in terms of the extent to which these criteria support the idea of a coherent externalizing spectrum of disorders.

RESULTS

This cluster distinguishes itself by the central role of disinhibitory personality in mental disorders spread throughout sections of the current classifications, including substance dependence, antisocial personality disorder and conduct disorder. Shared biomarkers, co-morbidity and course offer additional evidence for a valid cluster of externalizing disorders.

CONCLUSION

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

Exploring the feasibility of a meta-structure for DSM-V and ICD-11: could it improve utility and validity?

BACKGROUND

The organization of mental disorders into 16 DSM-IV and 10 ICD-10 chapters is complex and based on clinical presentation. We explored the feasibility of a more parsimonious meta-structure based on both risk factors and clinical factors.

METHOD

Most DSM-IV disorders were allocated to one of five clusters as a starting premise. Teams of experts then reviewed the literature to determine within-cluster similarities on 11 predetermined validating criteria. Disorders were included and excluded as determined by the available data. These data are intended to inform the grouping of disorders in the DSM-V and ICD-11 processes.

RESULTS

The final clusters were neurocognitive (identified principally by neural substrate abnormalities), neurodevelopmental (identified principally by early and continuing cognitive deficits), psychosis (identified principally by clinical features and biomarkers for information processing deficits), emotional (identified principally by the temperamental antecedent of negative emotionality), and externalizing (identified principally by the temperamental antecedent of disinhibition).

CONCLUSIONS

Large groups of disorders were found to share risk factors and also clinical picture. There could be advantages for clinical practice, public administration and research from the adoption of such an organizing principle.

The psychoses: cluster 3 of the proposed meta-structure for DSM-V and ICD-11

BACKGROUND

In an effort to group mental disorders on the basis of etiology, five clusters have been proposed. Here we consider the validity of the cluster comprising selected psychotic and related disorders.

METHOD

A group of diagnostic entities classified under schizophrenia and other psychotic disorders in DSM-IV-TR were assigned to this cluster and the bordering disorders, bipolar (BD) and schizotypal personality disorders (SPD), were included. We then reviewed the literature in relation to 11 validating criteria proposed by the DSM-V Task Force Study Group.

RESULTS

Relevant comparisons on the 11 spectrum criteria are rare for the included disorders except for schizophrenia and the two border conditions, BD and SPD. The core psychosis group is congruent at the level of shared psychotic psychopathology and response to antipsychotic medication. BD and SPD are exceptions in that psychosis is not typical in BD-II disorder and frank psychosis is excluded in SPD. There is modest similarity between schizophrenia and BD relating to risk factors, neural substrates, cognition and endophenotypes, but key differences are noted. There is greater support for a spectrum relationship of SPD and schizophrenia. Antecedent temperament, an important validator for other groupings, has received little empirical study in the various psychotic disorders.

CONCLUSIONS

The DSM-IV-TR grouping of psychotic disorders is supported by tradition and shared psychopathology, but few data exist across these diagnoses relating to the 11 spectrum criteria. The case for including BD is modest, and the relationship of BD to other mood disorders is addressed elsewhere. Evidence is stronger for inclusion of SPD, but the relationship with other personality disorders along the 11 criteria is not addressed and the absence of psychosis presents a conceptual problem. There are no data along the 11 spectrum criteria that are decisive for a cluster based on etiology, and inclusion of BD and SPD is questionable.

Rural environments reduce the genetic influence on adolescent substance use and rule-breaking behavior

BACKGROUND

There is increasing evidence that certain environmental factors can modify genetic effects. This is an important area of investigation as such work will help to guide the development of new intervention programs. In this paper, we address whether rural environments moderate the genetic influence on adolescent substance use and rule-breaking behavior (i.e. externalizing psychopathology).

METHOD

Over 1200 Minnesotan 17-year-old twins were classified as either urban or rural. Externalizing behavior was operationalized as the use and abuse of alcohol and drugs along with symptoms of conduct, oppositional defiant, and antisocial personality disorders. Biometric factor modeling estimated whether the relative contribution of genetic and shared environmental factors varied from urban to rural settings.

RESULTS

Residency effects reached statistical significance in the male sample only. In urban environments, externalizing behavior was substantially influenced by genetic factors, but in rural environments, shared environmental factors became more influential. This was apparent at both the individual-variable and factor levels.

CONCLUSIONS

These findings suggest a gene-environment interaction in the development of male adolescents' problem behaviors, including substance use. The results fit within an expanding literature demonstrating both the contextual nature of the heritability statistic and how certain environments may constrain the expression of genetic tendencies.

Altruism and antisocial behavior: independent tendencies, unique personality correlates, distinct etiologies

The relationship between altruism and antisocial behavior has received limited attention because altruism and antisocial behavior tend to be studied and discussed in distinct literatures. Our research bridges these literatures by focusing on three fundamental questions. First, are altruism and antisocial behavior opposite ends of a single dimension, or can they coexist in the same individual? Second, do altruism and antisocial behavior have the same or distinct etiologies? Third, do they stem from the same or from distinct aspects of a person's personality? Our findings indicate that altruism and antisocial behavior are uncorrelated tendencies stemming from different sources. Whereas altruism was linked primarily to shared (i.e., familial) environments, unique (i.e., nonfamilial) environments, and personality traits reflecting positive emotionality, antisocial behavior was linked primarily to genes, unique environments, and personality traits reflecting negative emotionality and a lack of constraint.

Phenotypic, genetic, and nonshared environmental parallels in the structure of personality: a view from the multidimensional personality questionnaire

How closely do observed, phenotypic personality structures correspond with underlying, genetic, and environmental personality structures? This question was addressed using data from 2,490 pairs of twins from the Minnesota Twin Registry, who completed A. Tellegen's (1982) Multidimensional Personality Questionnaire (MPQ). Phenotypic, additive genetic, and nonshared environmental correlations were computed among the MPQ's eleven primary scales. Principal component analyses of all three matrices revealed three broad, higher-order components that were readily interpreted as negative emotionality, positive emotionality, and constraint. The components from all three matrices were highly comparable, suggesting that the observed, phenotypic structure of personality corresponds closely with the underlying, etiological structure of personality.

Using item response theory to understand comorbidity among anxiety and unipolar mood disorders

The authors hypothesized that anxiety and unipolar mood disorders are often comorbid because each disorder indicates a broad, higher order factor. In a clinical subsample of the nationally representative National Comorbidity Survey participants (N = 251), a one-factor model fit the correlations among 7 dichotomous anxiety and unipolar mood diagnoses. Following the lead provided by literature on the structure of emotional and behavioral problems in children, we labeled this factor internalizing. Item response theory was used to explore how each diagnosis mapped onto the internalizing factor. The test information function derived from the 7 diagnoses suggested that they measure primarily the higher end of the factor. In addition, very high scores on internalizing (meeting criteria for 6-7 disorders) were associated with increased social costs, a phenomenon not well captured by the "comorbidity" concept. The results underscore the need to develop clinical assessment instruments that span the full range of the internalizing factor and measure both the shared and distinctive features of anxiety and unipolar mood disorders in a graded, continuous fashion.

Personality disorders in children and adolescents

The personality disorder (PD) construct continues to be controversial when applied to children and adolescents. Nevertheless, recent research indicates that PDs do occur in youth, and that PDs in youth have meaningful correlates and consequences. We provide a brief review of research on this topic from the past year, and we suggest that evidence for the reality of PDs in youth should be complemented by considerations from the adult PD literature regarding the importance of moving toward a dimensional descriptive system for PDs.

Epidemiological personology: the unifying role of personality in population-based research on problem behaviors

Epidemiological personology refers to a paradigm in which a developmental perspective on individual differences is paired with a population-based sampling frame to yield insights about the role of personality in consequential social outcomes. We review our work in epidemiological personology, linking personality to diverse, problematic social outcomes: Mental disorders, health-risk behaviors, and violence. We conclude that broad-band personality measurement is both feasible and fruitful in large-scale research on problem behaviors, and we call for increased collaboration between personality psychologists and researchers in fields such as public health, epidemiology, and sociology.

Phenotypic, genetic, and nonshared environmental parallels in the structure of personality: a view from the multidimensional personality questionnaire

How closely do observed, phenotypic personality structures correspond with underlying, genetic, and environmental personality structures? This question was addressed using data from 2,490 pairs of twins from the Minnesota Twin Registry, who completed A. Tellegen's (1982) Multidimensional Personality Questionnaire (MPQ). Phenotypic, additive genetic, and nonshared environmental correlations were computed among the MPQ's eleven primary scales. Principal component analyses of all three matrices revealed three broad, higher-order components that were readily interpreted as negative emotionality, positive emotionality, and constraint. The components from all three matrices were highly comparable, suggesting that the observed, phenotypic structure of personality corresponds closely with the underlying, etiological structure of personality.

The structure of common mental disorders

BACKGROUND

This report presents the results of confirmatory factor analyses of patterns of comorbidity among 10 common mental disorders in the National Comorbidity Survey, a national probability sample of US civilians who completed structured diagnostic interviews.

METHODS

Patterns of comorbidity among DSM-III-R mental disorders were analyzed via confirmatory factor analyses for the entire National Comorbidity Survey sample (N = 8098; age range, 15-54 years), for random halves of the sample, for men and women separately, and for a subsample of participants who were seeing a professional about their mental health problems. Four models were compared: a 1-factor model, a 2-factor model in which some disorders represented internalizing problems and others represented externalizing problems, a 3-factor variant of the 2-factor model in which internalizing was modeled as having 2 subfactors (anxious-misery and fear), and a 4-factor model in which the disorders represented separate affective, anxiety, substance dependence, and antisocial factors.

RESULTS

The 3-factor model provided the best fit in the entire sample. This result was replicated across random halves of the sample as well as across women and men. The substantial empirical intercorrelation between anxious-misery and fear (0.73) suggested that these factors were most appropriately conceived as subfactors of a higher-order internalizing factor. In the treatment sample, the 2-factor model fit best.

CONCLUSIONS

The results offer a novel perspective on comorbidity, suggesting that comorbidity results from common, underlying core psychopathological processes. The results thereby argue for focusing research on these core processes themselves, rather than on their varied manifestations as separate disorders.

Personality traits in late adolescence predict mental disorders in early adulthood: a prospective-epidemiological study

Prospective relations between personality traits and mental disorders were assessed in a longitudinal study of a representative birth cohort of young men and women from Dunedin, New Zealand. Personality traits were assessed via self-report questionnaire at age 18, and mental disorders were assessed via diagnostic interview at both ages 18 and 21. High "negative emotionality" (a propensity to experience aversive affective states) at age 18 was linked with affective, anxiety, substance dependence, and antisocial personality disorders at age 21 when corresponding mental disorders at age 18 were controlled. Low "constraint" (difficulty inhibiting the expression of affect and impulse) at age 18 was linked with substance dependence and antisocial personality disorders at age 21 when corresponding mental disorders at age 18 were controlled. The findings are discussed in terms of their implications for the development and treatment of mental disorders in young adulthood.

The structure and stability of common mental disorders (DSM-III-R): a longitudinal-epidemiological study

The latent structure and stability of 10 common mental disorders were examined in a birth cohort at ages 18 and 21. A 2-factor model, in which some disorders were presumed to reflect internalizing problems and others were presumed to reflect externalizing problems, provided a more optimal fit to the data than either a 1- or a 4-factor model. To a significant extent, persons in the sample retained their relative positions on the latent factors across the 3-year period from age 18 to age 21. Results offer potential clarification of the meaning of comorbidity in psychopathology research by suggesting that comorbidity may results from common mental disorders being reliable, covariant indicators of stable, underlying "core psychopathological processes."

The structure and stability of common mental disorders (DSM-III-R): a longitudinal-epidemiological study

The latent structure and stability of 10 common mental disorders were examined in a birth cohort at ages 18 and 21. A 2-factor model, in which some disorders were presumed to reflect internalizing problems and others were presumed to reflect externalizing problems, provided a more optimal fit to the data than either a 1- or a 4-factor model. To a significant extent, persons in the sample retained their relative positions on the latent factors across the 3-year period from age 18 to age 21. Results offer potential clarification of the meaning of comorbidity in psychopathology research by suggesting that comorbidity may results from common mental disorders being reliable, covariant indicators of stable, underlying "core psychopathological processes."

Assortative mating for antisocial behavior: developmental and methodological implications

Do people mate assortatively for antisocial behavior? If so, what are the implications for the development and persistence of antisocial behavior? We investigated assortative mating for antisocial behavior and its correlates in a sample of 360 couples from Dunedin, New Zealand. We found substantial assortative mating for self-reports of antisocial behavior per se and for self-reports of couple members' tendencies to associate with antisocial peers (0.54 on average). Perceptions about the likelihood of social sanctions for antisocial behavior (e.g., being caught by the authorities or losing the respect of one's family) showed moderate assortative mating (0.32 on average). However, assortative mating for personality traits related to antisocial behavior was low (0.15 on average). These findings suggest that, whereas assortative mating for many individual-difference variables (such as personality traits) is low, assortative mating for actual antisocial behaviors is substantial. We conclude that future family studies of antisocial behavior should endeavor to measure and understand the influence of assortative mating. In addition, we outline a testable behavior-genetic model for the development of antisocial behavior, in which genes and environments promoting or discouraging antisocial behavior become concentrated within families (due to assortative mating), giving rise to widely varying individual developmental trajectories that are, nevertheless, similar within families.

Personality traits are differentially linked to mental disorders: a multitrait-multidiagnosis study of an adolescent birth cohort

The authors assessed the relation between personality and mental disorder in a representative birth cohort of 897 men and women. Personality was assessed at age 18 with the Multidimensional Personality Questionnaire (MPQ; A. Tellegen, 1982), and 4 types of mental disorder (affective, anxiety, substance dependence, and conduct disorder) were assessed at ages 15, 18 and 21, using age-appropriate standardized diagnostic interviews. All disorder groups had MPQ profiles that were very different from those of controls. When comorbid cases were excluded, fewer significant differences between diagnosed cases and controls remained. Relations between personality and mental disorder were not affected by the measurement of disorder as continuous versus discrete, gender, or the age at which disorder was diagnosed. Relations between personality and mental disorders appear to be robust, and individual personality differences may be particularly relevant to understanding the most severe (comorbid) expressions of psychopathology.

Delay of gratification, psychopathology, and personality: is low self-control specific to externalizing problems?

We assessed the delay of gratification behavior of 428 twelve- and thirteen-year-old boys, half of whom were known to manifest symptoms of behavioral disturbance. Consistent with the hypothesis that low self-control is a risk factor specific to externalizing (aggressive and delinquent) disorders, boys who showed signs of externalizing disorders tended to seek immediate gratification in a laboratory task more often than both nondisordered boys and boys who showed signs of internalizing (anxious and depressed) disorders. In addition, children who were able to delay immediate gratification were described by their mothers as ego controlled, ego resilient, conscientious, open to experience, and agreeable. These results suggest that poor delay of gratification may be one of a select number of specific risk factors for externalizing disorder, and that good delay of gratification is linked to multiple adaptive tendencies in early adolescence.

Personality traits are linked to crime among men and women: evidence from a birth cohort

Is there a relationship between personality and criminal behavior? We addressed this question in a representative birth cohort of 862 male and female 18-year-olds. Personality was assessed with the Multidimensional Personality Questionnaire (MPQ). The MPQ measures 10 relatively independent personality traits and was not designed to identify offenders. Delinquency was assessed via 3 data sources: self-reports, informant reports, and official records. Variable-centered analyses revealed that MPQ scales indexing negative emotionality and behavioral constraint were consistent predictors of delinquency across the 3 data sources. Person-centered analyses revealed that youths abstaining from delinquency were uniquely characterized by low interpersonal potency. Youths involved in extensive delinquency were uniquely characterized by feelings of alienation, lack of social closeness, and risk taking. Advances in understanding criminal behavior can be made through research that places the personality-delinquency link in a developmental context.

Personality traits are linked to crime among men and women: evidence from a birth cohort

Is there a relationship between personality and criminal behavior? We addressed this question in a representative birth cohort of 862 male and female 18-year-olds. Personality was assessed with the Multidimensional Personality Questionnaire (MPQ). The MPQ measures 10 relatively independent personality traits and was not designed to identify offenders. Delinquency was assessed via 3 data sources: self-reports, informant reports, and official records. Variable-centered analyses revealed that MPQ scales indexing negative emotionality and behavioral constraint were consistent predictors of delinquency across the 3 data sources. Person-centered analyses revealed that youths abstaining from delinquency were uniquely characterized by low interpersonal potency. Youths involved in extensive delinquency were uniquely characterized by feelings of alienation, lack of social closeness, and risk taking. Advances in understanding criminal behavior can be made through research that places the personality-delinquency link in a developmental context.

Tilorone hydrochloride: mode of action

An antiviral serum component is found in mice treated orally with tilorone hydrochloride. The active material fulfills sufficient biological criteria to be classified as an interferon.