Reinterpreting comorbidity: a model-based approach to understanding and classifying psychopathology

The joint structure of DSM-IV Axis I and Axis II disorders

The Diagnostic and Statistical Manual (4th ed. [DSM-IV]; American Psychiatric Association, 1994) distinction between clinical disorders on Axis I and personality disorders on Axis II has become increasingly controversial. Although substantial comorbidity between axes has been demonstrated, the structure of the liability factors underlying these two groups of disorders is poorly understood. The aim of this study was to determine the latent factor structure of a broad set of common Axis I disorders and all Axis II personality disorders and thereby to identify clusters of disorders and account for comorbidity within and between axes. Data were collected in Norway, through a population-based interview study (N = 2,794 young adult twins). Axis I and Axis II disorders were assessed with the Composite International Diagnostic Interview (CIDI) and the Structured Interview for DSM-IV Personality (SIDP-IV), respectively. Exploratory and confirmatory factor analyses were used to investigate the underlying structure of 25 disorders. A four-factor model fit the data well, suggesting a distinction between clinical and personality disorders as well as a distinction between broad groups of internalizing and externalizing disorders. The location of some disorders was not consistent with the DSM-IV classification; antisocial personality disorder belonged primarily to the Axis I externalizing spectrum, dysthymia appeared as a personality disorder, and borderline personality disorder appeared in an interspectral position. The findings have implications for a meta-structure for the DSM.

Research planning for the future of psychiatric diagnosis

More than 10 years prior to the anticipated 2013 publication of DSM-5, processes were set in motion to assess the research and clinical issues that would best inform future diagnostic classification of mental disorders. These efforts intended to identify the clinical and research needs within various populations, examine the current state of the science to determine the empirical evidence for improving criteria within and across disorders, and stimulate research in areas that could potentially provide evidence for change. In the second phase of the revision process, the American Psychiatric Institute for Research and Education (APIRE) recently completed the 5-year international series of 13 diagnostic conferences convened by APA/APIRE in collaboration with the World Health Organization and the National Institutes of Health (NIH), under a cooperative grant funded by the NIH. From these conferences, the DSM-5 Task Force and Work Groups have developed plans for potential revisions for DSM-5, including the incorporation of dimensional approaches within and across diagnostic groups to clarify heterogeneity, improve diagnostic validity, and enhance clinical case conceptualization. Use of dimensions for measurement-based care has been shown to be feasible in psychiatric and primary care settings and may inform monitoring of disorder threshold, severity, and treatment outcomes. The integration of dimensions with diagnostic categories represents an exciting and potentially transformative approach for DSM-5 to simultaneously address DSM-IV's clinical short-comings and create novel pathways for research in neurobiology, genetics, and psychiatric epidemiology.

Comorbidity and risk indicators for alcohol use disorders among persons with anxiety and/or depressive disorders: findings from the Netherlands Study of Depression and Anxiety (NESDA)

INTRODUCTION

This study examines comorbidity of alcohol abuse and alcohol dependence as well as its risk indicators among anxious and/or depressed persons, also considering temporal sequencing of disorders.

METHODS

Baseline data from the Netherlands Study of Depression and Anxiety (NESDA) were used, including 2329 persons with lifetime DSM-IV anxiety (social phobia, generalized anxiety disorder, panic disorder, and agoraphobia) and/or depressive (major depressive disorder and dysthymia) disorders and 652 controls. Lifetime diagnoses of DSM-IV alcohol abuse and dependence were established, as well as information about socio-demographic, vulnerability, addiction-related and anxiety/depression-related characteristics. Temporal sequencing of disorders was established retrospectively, using age of onset.

RESULTS

Of persons with combined anxiety/depression 20.3% showed alcohol dependence versus 5.5% of controls. Prevalence of alcohol abuse was similar across groups (± 12%). Independent risk indicators for alcohol dependence among anxious and/or depressed persons were male gender, vulnerability factors (family history of alcohol dependence, family history of anxiety/depression, openness to experience, low conscientiousness, being single, and childhood trauma), addiction-related factors (smoking and illicit drug use) and early anxiety/depression onset. Persons with secondary alcohol dependence were more neurotic, more often single and lonelier, while persons with primary alcohol dependence were more often male and more extravert.

DISCUSSION

Alcohol dependence, but not abuse, is more prevalent in anxious and/or depressed persons. Persons with comorbid alcohol dependence constitute a distinct subgroup of anxious and/or depressed persons, characterized by addiction-related habits and vulnerability. However, considerable variation in characteristics exists depending on temporal sequencing of disorders. This knowledge may improve identification and treatment of those anxious and/or depressed patients who are additionally suffering from alcohol dependence.

Personality and psychopathology

Personality and psychopathology are increasingly recognized as tightly linked domains of study, despite historical and theoretical divisions. In this paper, we discuss the history of these divisions, models of inter-relations between personality and psychopathology, and selected examples from the literature demonstrating personality/psychopathology inter-relations in clinical and community populations. We begin by summarizing how personality, temperament, and personality disorders are increasingly conceptualized as overlapping entities. We next address relationships between personality traits and common mental illnesses/symptoms (e.g. internalizing and externalizing problems). Then we discuss the various ways in which personality traits may relate to Axis I conditions causally, with methods for distinguishing between them. We conclude with a more in-depth example, relating personality traits to schizophrenia.

The modeling of internalizing disorders on the basis of patterns of lifetime comorbidity: associations with psychosocial functioning and psychiatric disorders among first-degree relatives

Two broadband latent factors--internalizing and externalizing--have frequently been identified in studies of the hierarchical structure of psychopathology. In the present research, 3 competing measurement models of putative internalizing disorders (i.e., a parsimonious single-factor model, a model based on the Diagnostic and Statistical Manual of Mental Disorders [4th ed., American Psychiatric Association, 1994], and an alternative model proposed by Krueger, 1999, and Watson, 2005) were evaluated in terms of their ability to account for lifetime patterns of diagnostic comorbidity. Four diagnostic assessments were performed on an age-based cohort of 816 persons over a 15-year interval. Each of the 3 measurement models demonstrated adequate or good fit to the data and similar approximating abilities. Additional analyses, however, suggested that nonspecific aspects of lifetime mood/anxiety or distress/fear disorders (i.e., general negative affect) largely accounted for indicators of psychosocial functioning at age 30 as well as densities of specific psychiatric disorders among the 1st-degree relatives of probands. The relevance of these findings for theoretical and descriptive models of internalizing disorders is discussed.

Diagnosing the DSM: Diagnostic Classification Needs Fundamental Reform

If all goes as planned, the American Psychiatric Association will release a new Diagnostic and Statistical Manual of Mental Disorders (DSM-5) in May 2013. Since 1980, the DSM has provided a shared diagnostic language to clinicians, patients, scientists, school systems, courts, and pharmaceutical and insurance companies; any changes to the influential manual will have serious ramifications. But, argues Dr. Steven Hyman, the DSM is a poor mirror of clinical and biological realities; a fundamentally new approach to diagnostic classification is needed as researchers uncover novel ways to study and understand mental illness.

Strong genetic correlation between interview-assessed internalizing disorders and a brief self-report symptom scale

Self-report scales for symptoms of anxiety and depression are frequently used for screening and research purposes. A moderate phenotypic association between disorders measured by diagnostic interviews and symptoms of anxiety and depression measured by self-report scales has been shown, but little is known about the overlap in these phenotypes' genetic and environmental variance. In the present study, we used twin modeling to identify common genetic and environmental liabilities underlying the phenotypic association between the self-report Symptom Checklist-5 (SCL-5) and lifetime internalizing disorders derived from the Composite International Diagnostic Interview (CIDI). The sample consisted of 7,992 young adult twins from the Norwegian Institute of Public Health Twin Panel (NIPHT), who all responded to a questionnaire. A subset of 2,793 individuals later underwent structured interviews. The best fitting model showed a strong genetic correlation of 0.82 (95% confidence interval; 0.61-1.0) between current self-report symptoms of anxiety and depression, and lifetime internalizing disorders, which suggests an almost complete overlap in genetic liability. The correlation between environmental factors was much lower: 0.16 (0.00-0.34, 95% CI). This implies that brief self-report scales capture genetic variance that is highly overlapping with the genetic variance common to internalizing disorder diagnoses. It thus follows that SCL-5 and similar instruments may be used as screening instruments for genetic risk factors that influence liability to internalizing disorders. In addition, existing data on self-report symptoms of anxiety and depression can be used with increased confidence to specify models including effects from genes coding for internalizing disorders.

Stability and Invariance of Psychopathic Traits from Late Adolescence to Young Adulthood

The current study examined the longitudinal stability and invariance of psychopathic traits in a large community sample of male twins from ages 17 to 23. Participants were assessed across six years to gauge the stability and measurement invariance of the Minnesota Temperament Inventory (MTI), a Cleckley-based measure of psychopathic personality traits, and how family functioning and externalizing behavior were linked to these traits. A latent variable approach was used to model the structure of the MTI and provide a statistical test of measurement invariance across time. The results revealed support for invariance and moderate to strong stability of the MTI factors, which showed significant associations with the external correlates in late adolescence but not early adulthood.

Deriving an empirical structure of personality pathology for DSM-5

The DSM-IV model of personality disorders is composed of trait sets arranged into 10 theoretically distinct, polythetically assessed categories, with little regard for how the traits comprising these disorders are interrelated and structured. Research since the publication of DSM-III has shown that this model is untenable. The question is not whether this model needs revision; rather, the question is how to move from the existing DSM-IV framework to a model better connected with data. Empirically-based models of personality trait variation provide a starting point for DSM-5, and ongoing research will be used to delineate further the empirical structure of personality traits in the pathological range. The ultimate goal is to frame future DSMs in a way that is maximally useful for clinicians as well as researchers. It is also critical to understand that the DSM-5 is intended to be a living document that will facilitate novel inquiry and clinical applications, as opposed to a document designed to promote and perpetuate a fixed set of constructs. Thus, we view a proposed trait system as a first step on a path to a well-validated, clinically-useful structure.

Rumination as a transdiagnostic factor in depression and anxiety

The high rate of comorbidity among mental disorders has driven a search for factors associated with the development of multiple types of psychopathology, referred to as transdiagnostic factors. Rumination is involved in the etiology and maintenance of major depression, and recent evidence implicates rumination in the development of anxiety. The extent to which rumination is a transdiagnostic factor that accounts for the co-occurrence of symptoms of depression and anxiety, however, has not previously been examined. We investigated whether rumination explained the concurrent and prospective associations between symptoms of depression and anxiety in two longitudinal studies: one of adolescents (N=1065) and one of adults (N=1317). Rumination was a full mediator of the concurrent association between symptoms of depression and anxiety in adolescents (z=6.7, p< .001) and was a partial mediator of this association in adults (z=5.6, p< .001). In prospective analyses in the adolescent sample, baseline depressive symptoms predicted increases in anxiety, and rumination fully mediated this association (z=5.26, p< .001). In adults, baseline depression predicted increases in anxiety and baseline anxiety predicted increases in depression; rumination fully mediated both of these associations (z=2.35, p= .019 and z=5.10, p< .001, respectively). These findings highlight the importance of targeting rumination in transdiagnostic treatment approaches for emotional disorders.

Development of lifetime comorbidity in the World Health Organization world mental health surveys

CONTEXT

Although numerous studies have examined the role of latent variables in the structure of comorbidity among mental disorders, none has examined their role in the development of comorbidity.

OBJECTIVE

To study the role of latent variables in the development of comorbidity among 18 lifetime DSM-IV disorders in the World Health Organization World Mental Health Surveys.

DESIGN

Nationally or regionally representative community surveys.

SETTING

Fourteen countries.

PARTICIPANTS

A total of 21 229 survey respondents.

MAIN OUTCOME MEASURES

First onset of 18 lifetime DSM-IV anxiety, mood, behavior, and substance disorders assessed retrospectively in the World Health Organization Composite International Diagnostic Interview.

RESULTS

Separate internalizing (anxiety and mood disorders) and externalizing (behavior and substance disorders) factors were found in exploratory factor analysis of lifetime disorders. Consistently significant positive time-lagged associations were found in survival analyses for virtually all temporally primary lifetime disorders predicting subsequent onset of other disorders. Within-domain (ie, internalizing or externalizing) associations were generally stronger than between-domain associations. Most time-lagged associations were explained by a model that assumed the existence of mediating latent internalizing and externalizing variables. Specific phobia and obsessive-compulsive disorder (internalizing) and hyperactivity and oppositional defiant disorders (externalizing) were the most important predictors. A small number of residual associations remained significant after controlling the latent variables.

CONCLUSIONS

The good fit of the latent variable model suggests that common causal pathways account for most of the comorbidity among the disorders considered herein. These common pathways should be the focus of future research on the development of comorbidity, although several important pairwise associations that cannot be accounted for by latent variables also exist that warrant further focused study.

Some new directions for research on psychological interventions for comorbid anxiety and substance use disorders

ISSUES

Comorbidity between anxiety and substance use disorders is common, yet it is poorly understood and poorly treated.

APPROACH

Narrative literature review. PsycINFO and Medline databases were searched for clinical trials of anxiety and substance use disorders using clinical queries for 2005-2009.

KEY FINDINGS

There are few well-conducted treatment outcome trials for comorbid anxiety and substance use disorders. Some recent (2005-2009) outcome literature has focused on specific mechanisms (anxiety sensitivity and tension reduction alcohol expectancies) that may underlie comorbidity between anxiety and substance use disorders and may lead to more targeted intervention. IMPLICATIONS AND CONCLUSION: The research base for understanding and treating comorbid anxiety and substance use disorders needs to be broadened. In particular research is needed with a focus on: (i) specifying particular comorbid relationships between anxiety and substance use disorders; (ii) the mechanisms that may underlie and maintain those relationships; and (iii) well-conducted evaluations of treatments that target those mechanisms.

Sex differences amongst dependent heroin users: histories, clinical characteristics and predictors of other substance dependence

INTRODUCTION AND AIMS

To examine differences in the characteristics and histories of male and female dependent heroin users, and in the clinical characteristics associated with multiple substance dependence diagnoses.

DESIGN AND METHODS

1513 heroin dependent participants underwent an interview covering substance use and dependence, psychiatric history, child maltreatment, family background, adult violence and criminal history. Family background, demographic and clinical characteristics were analysed by sex. Ordinal regression was used to test for a relationship between number of substance dependence diagnoses and other clinical variables.

RESULTS

Women were more likely to experience most forms of child maltreatment, to first use heroin with a boyfriend or partner, to experience ongoing adult violence at the hands of a partner, and to have a poorer psychiatric history than men. Males had more prevalent lifetime substance dependence diagnoses and criminal histories and were more likely to meet the criteria for ASPD. Predictors of multiple substance dependence diagnoses for both sexes were mental health variables, antisocial behaviour, childhood sexual abuse, victim of adult violence, younger age at first cannabis use and overdose. As the number of dependence diagnoses increased, clinical and behavioural problems increased. Childhood emotional neglect was related to increasing dependence diagnoses for females but not males, whereas PTSD was a significant predictor for males but not females.

DISCUSSION AND CONCLUSIONS

Mental health problems, other substance dependence, childhood and adult trauma were common in this sample, with sex differences indicating different treatment needs and possible different pathways to heroin dependence for men and women.

The effects of latent variables in the development of comorbidity among common mental disorders

BACKGROUND

Although numerous studies have examined the role of latent predispositions to internalizing and externalizing disorders in the structure of comorbidity among common mental disorders, none examined latent predispositions in predicting development of comorbidity.

METHODS

A novel method was used to study the role of latent variables in the development of comorbidity among lifetime DSM-IV disorders in the National Comorbidity Surveys. Broad preliminary findings are briefly presented to describe the method. The method used survival analysis to estimate time-lagged associations among 18 lifetime DSM-IV anxiety, mood, behavior, and substance disorders. A novel estimation approach examined the extent to which these predictive associations could be explained by latent canonical variables representing internalizing and externalizing disorders.

RESULTS

Consistently significant positive associations were found between temporally primary and secondary disorders. Within-domain time-lagged associations were generally stronger than between-domain associations. The vast majority of associations were explained by a model that assumed mediating effects of latent internalizing and externalizing variables, although the complexity of this model differed across samples. A number of intriguing residual associations emerged that warrant further investigation.

CONCLUSIONS

The good fit of the canonical model suggests that common causal pathways account for most comorbidity among the disorders considered. These common pathways should be the focus of future research on the development of comorbidity. However, the existence of several important residual associations shows that more is involved than simple mediation. The method developed to carry out these analyses provides a unique way to pinpoint these significant residual associations for subsequent focused study.

Psychometric and genetic architecture of substance use disorder and behavioral disinhibition measures for gene association studies

Using large twin, family, and adoption studies conducted at the Minnesota Center for Twin and Family Research, we describe our efforts to develop measures of substance use disorder (SUD) related phenotypes for targets in genome wide association analyses. Beginning with a diverse set of relatively narrow facet-level measures, we identified 5 constructs of intermediate complexity: nicotine, alcohol consumption, alcohol dependence, illicit drug, and behavioral disinhibition. The 5 constructs were moderately correlated (mean r = .57) reflecting a general externalizing liability to substance abuse and antisocial behavior. Analyses of the twin and adoption data revealed that this general externalizing liability accounted for much of the genetic risk in each of the intermediate-level constructs, though each also exhibited significant unique genetic and environmental risk. Additional analyses revealed substantial effects for age and sex, significant shared environmental effects, and that the mechanism of these shared environmental effects operates via siblings rather than parents. Our results provide a foundation for genome wide association analyses to detect risk alleles for SUDs as well as novel insights into genetic and environmental risk for SUDs.

A rational model for maximizing the effects of therapeutic relationship regulation in personality disorders with poor metacognition and over-regulation of affects

BACKGROUND

The therapeutic relationship plays a key role in personality disorder (PD) psychotherapy. Some aspects of therapeutic relationship regulation appear important for treatment of PD clients, including those with constricted relational schemas, poor metacognition, and over-regulation of affects described here. AIM.: To propose a rational model for how and when to work on the therapeutic relationship by treating the underlying personality pathology.

METHOD

Formalize a step-by-step procedure for performing operations such as validation of clients' experiences, creating a sense of sharedness, assessing the quality of the therapeutic relationship in order to prevent and repair ruptures in the alliance, self-disclosing by the therapist, and metacommunication on the basis of clients' responses to treatment.

CONCLUSION

We discuss the implications of this model for further research into the PD therapy process.

Longitudinal associations between post-traumatic distress and depressive symptoms following a traumatic event: a test of three models

BACKGROUND

Symptoms of post-traumatic stress disorder (PTSD) and depression are highly co-morbid following a traumatic event. Nevertheless, decisive evidence regarding the direction of the relationship between these clinical entities is missing.

METHOD

The aim of the present study was to examine the nature of this relationship by comparing a synchronous change model (PTSD and depression are time synchronous, possibly stemming from a third common factor) with a demoralization model (i.e. PTSD symptoms causing depression) and a depressogenic model (i.e. depressive symptoms causing PTSD symptoms). Israeli adult victims of single-event traumas (n=156) were assessed on measures of PTSD and depression at 2, 4 and 12 weeks post-event.

RESULTS

A cross-lagged structural equation modeling (SEM) analysis provided results consistent with the synchronous change model and the depressogenic model.

CONCLUSIONS

Depressive symptoms may play an important role in the development of post-traumatic symptoms.

Toward scientifically useful quantitative models of psychopathology: the importance of a comparative approach

Cramer et al. articulate a novel perspective on comorbidity. However, their network models must be compared with more parsimonious latent variable models before conclusions can be drawn about network models as plausible accounts of comorbidity. Latent variable models have proven generative in studying psychopathology and its external correlates, and we doubt network models will prove as useful for psychopathology research.

Psychometric characteristics and clinical correlates of NEO-PI-R fearless dominance and impulsive antisociality in the Collaborative Longitudinal Personality Disorders Study

This study evaluates the validity of derived measures of the psychopathic personality traits of Fearless Dominance and Impulsive Antisociality from the NEO Personality Inventory-Revised (NEO-PI-R; Costa & McCrae, 1992) using data from the Collaborative Longitudinal Personality Disorders Study (baseline N = 733). These 3 issues were examined: (a) the stability of the measures over a 10-year interval, (b) their criterion-related validity, and (c) their incremental validity relative to an alternative NEO-PI-R profile-rating approach for assessing psychopathy. NEO-PI-R Fearless Dominance and Impulsive Antisociality scales were relatively stable across 10 years and demonstrated differential associations with measures of personality pathology and psychopathology generally consistent with past research and theoretical considerations. Moreover, these measures demonstrated an appreciable degree of incremental validity over the NEO-PI-R profile-rating approach.

Familial transmission and heritability of childhood disruptive disorders

OBJECTIVE

There is substantial evidence of a link between parental substance use disorders and antisocial behavior and childhood disruptive disorders in offspring, but it is unclear whether this transmission is specific to particular disorders or if a general liability accounts for familial resemblance. The authors examined whether the association between parental externalizing disorders and childhood disruptive disorders in preadolescent offspring is a result of the transmission of general or disorder-specific liabilities and estimated the genetic and environmental contributions to variation in these general and specific liability indicators.

METHOD

Participants were 1,069 families consisting of 11-year-old twins and their biological mother and father. Structural equation modeling was used to simultaneously estimate the general and specific transmission effects of four parental externalizing disorders (conduct disorder, adult antisocial behavior, alcohol dependence, and drug dependence) on childhood disruptive disorders (attention deficit hyperactivity disorder, conduct disorder, and oppositional defiant disorder).

RESULTS

Parent-child resemblance was accounted for by the transmission of a general liability to externalizing disorders, and this general liability was highly heritable. Specific effects were also detected, but for sibling rather than parental transmission. Specific genetic and nonshared environmental effects were detected for each childhood disruptive disorder, but only conduct disorder exhibited a significant shared environmental effect.

CONCLUSIONS

A highly heritable general liability accounts for the parent-child transmission of externalizing psychopathology from parents to their preadolescent offspring. This general liability should be a focus of research for both etiology and intervention.

Major depression and dimensional representations of DSM-IV personality disorders: a population-based twin study

BACKGROUND

Major depressive disorder (MDD) co-occurs frequently with personality disorders (PDs). The extent to which this results from shared genetic or environmental risk factors remains uncertain.

METHOD

Young adult twins (n=2801) from the population-based Norwegian Institute of Public Health Twin Panel were assessed at personal interview for DSM-IV lifetime MDD and the 10 Axis II PDs. The relationship between MDD and dimensional representations of all PDs was explored by stepwise logistic regression. Multivariate Cholesky twin models were fitted using the Mx program, and genetic and environmental correlations were estimated.

RESULTS

Dimensional representations of borderline (BPD), avoidant (AVPD) and paranoid personality disorder (PPD) were independently and significantly associated with increased risk for MDD. Multivariate twin modeling indicated that one latent factor accounted for the genetic covariance between MDD and the three PDs. The genetic correlations between MDD and dimensional representations of BPD, AVPD and PPD were +0.56, +0.22 and +0.40 respectively. No sex differences or shared environmental effects were found. The structure of the individual-specific environmental factors influencing MDD and the three PDs were similar to the genetic factors but the environmental correlations were lower: +0.39, +0.23 and +0.27 respectively.

CONCLUSIONS

There is substantial overlap between liability factors for MDD and BPD from cluster B, PPD from cluster A and AVPD from cluster C. The vulnerability to general PD pathology and MDD seem to be closely related. The patterns of co-morbidity observed between diverse psychiatric disorders might result from just a few liability factors.

Posttraumatic stress disorder and the genetic structure of comorbidity

This study used structural equation modeling to examine the genetic and environmental architecture of latent dimensions of internalizing and externalizing psychiatric comorbidity and explored structural associations between posttraumatic stress disorder (PTSD) and these dimensions. Data were drawn from the Vietnam Era Twin Registry and included lifetime diagnoses for PTSD and a range of other psychiatric disorders for 3,372 male-male twin pairs. Examination of the phenotypic structure of these disorders revealed that PTSD cross-loaded on both Internalizing and Externalizing common factors. Biometric analyses suggested largely distinct genetic risk factors for the latent internalizing and externalizing comorbidity dimensions, with the total heritability of the Externalizing factor (69%) estimated to be significantly stronger than that for Internalizing (41%). Nonshared environment explained the majority of the remaining variance in the Internalizing (58%) and Externalizing (20%) factors. Shared genetic variance across the 2 dimensions explained 67% of their phenotypic correlation (r = .52). These findings have implications for conceptualizations of the etiology of PTSD and its location in an empirically based nosology.

Longitudinal dimensionality of adolescent psychopathology: testing the differentiation hypothesis

BACKGROUND

The differentiation hypothesis posits that the underlying liability distribution for psychopathology is of low dimensionality in young children, inflating diagnostic comorbidity rates, but increases in dimensionality with age as latent syndromes become less correlated. This hypothesis has not been adequately tested with longitudinal psychiatric symptom data.

METHODS

Confirmatory factor analyses of DSM-IV symptoms from seven common Axis I syndromes--major depression, generalized anxiety, separation anxiety, social anxiety, attention deficient hyperactivity, conduct, and oppositional defiant disorders--were conducted longitudinally, from ages 9 to 16, using the general-population Great Smoky Mountains Study sample.

RESULTS

An eight-syndrome model fit well at all ages, and in both genders. It included social anxiety, separation anxiety, oppositional defiant, and conduct syndromes, along with a multidimensional attention deficit-hyperactivity syndrome (i.e., inattention, hyperactivity, and impulsivity) and a unidimensional major depression/generalized anxiety syndrome. A high degree of measurement invariance across age was found for all syndromes, except for major depression/generalized anxiety. Major depression and generalized anxiety syndromes slightly diverged at age 14-16, when they also began to explain more symptom variance. Additionally, correlations between some emotional and disruptive syndromes showed slight differentiation.

CONCLUSIONS

Marked developmental differentiation of psychopathology, as implied by the orthogenetic principle, is not a prominent cause of preadolescent and adolescent psychiatric comorbidity.

A self-regulatory model of behavioral disinhibition in late adolescence: integrating personality traits, externalizing psychopathology, and cognitive capacity

Two samples with heterogeneous prevalence of externalizing psychopathology were used to investigate the structure of self-regulatory models of behavioral disinhibition and cognitive capacity. Consistent with expectations, structural equation modeling in the first sample (N=541) showed a hierarchical model with 3 lower order factors of impulsive sensation seeking, antisociality/unconventionality, and lifetime externalizing problem counts, with a behavioral disinhibition superfactor best accounted for the pattern of covariation among 6 disinhibited personality trait indicators and 4 externalizing problem indicators. The structure was replicated in a second sample (N=463) and showed that the behavioral disinhibition superfactor, and not the lower order impulsive sensation seeking, antisociality/unconventionality, and externalizing problem factors, was associated with lower IQ, reduced short-term memory capacity, and reduced working memory capacity. The results provide a systemic and meaningful integration of major self-regulatory influences during a developmentally important stage of life.

Externalising and emotional categories, diagnostic groups and clinical profiles

Background

It has been proposed that gains would be made in the validity of the psychiatric classification system if many of the present 'neurotic' or personality disorders were subsumed into two over-arching groups, externalising and emotional disorders. If diagnostic sub-categories from the first digit coding structures within ICD-10 do, in fact, share clinical phenomenology that align with the major externalising/emotional distinction, this further supports the proposal and contributes to face validity. The aim of the study was to examine the distribution of particular psychopathology within and between two proposed over-arching groupings - externalising and emotional disorders - in a clinical sample.

Method

The distributions of HoNOS derived information in relation to the proposed clusters of emotional disorders and extrinsic disorders are examined.

Results

Statistically significant differences in profiles between the emotional and the externalising groupings are consistent with the proposed classification development. The HoNOS (Health of Nation Outcome Scale) measures of self harm, depression, aggression, occupational/leisure problems and drug and alcohol consumption are the five most significant discriminators between the two groups.

Discussion

The details of the profile differences within the two over arching groups suggest that further examination is required. Useful work could include examination in credibly large and unselected patient populations of the factor structure demonstrated in non patient samples. Prospective comprehensive trials of the contributions the proposed classification could make to clinical decision making would also help illuminate this area.

The diagnosis of mental disorders: the problem of reification

A pressing need for interrater reliability in the diagnosis of mental disorders emerged during the mid-twentieth century, prompted in part by the development of diverse new treatments. The Diagnostic and Statistical Manual of Mental Disorders (DSM), third edition answered this need by introducing operationalized diagnostic criteria that were field-tested for interrater reliability. Unfortunately, the focus on reliability came at a time when the scientific understanding of mental disorders was embryonic and could not yield valid disease definitions. Based on accreting problems with the current DSM-fourth edition (DSM-IV) classification, it is apparent that validity will not be achieved simply by refining criteria for existing disorders or by the addition of new disorders. Yet DSM-IV diagnostic criteria dominate thinking about mental disorders in clinical practice, research, treatment development, and law. As a result, the modern DSM system, intended to create a shared language, also creates epistemic blinders that impede progress toward valid diagnoses. Insights that are beginning to emerge from psychology, neuroscience, and genetics suggest possible strategies for moving forward.

Continuous, categorical and mixture models of DSM-IV alcohol and cannabis use disorders in the Australian community

AIMS

To apply item response mixture modelling (IRMM) to investigate the viability of the dimensional and categorical approaches to conceptualizing alcohol and cannabis use disorders.

DESIGN

A cross-sectional survey assessing substance use and DSM-IV substance use disorders.

SETTING AND PARTICIPANTS

A household survey of a nationally representative sample of 10,641 Australia adults (aged 18 years or older).

MEASUREMENTS

Trained survey interviewers administered a structured interview based on the Composite International Diagnostic Interview (CIDI).

FINDINGS

Of the 10,641 Australian adults interviewed, 7746 had drunk alcohol in the past 12 months and 722 had used cannabis. There was no improvement in fit for categorical latent class nor mixture models combining continuous and categorical parameters compared to continuous factor analysis models. The results indicated that both alcohol and cannabis problems can be considered as dimensional, with those with the disorder arrayed along a dimension of severity.

CONCLUSIONS

A single factor accounts for more variance in the DSM-IV alcohol and cannabis use criteria than latent class or mixture models, so the disorders can be explained most effectively by a dimensional score.

Neuroticism as a common dimension in the internalizing disorders

BACKGROUND

Several theories have posited a common internalizing factor to help account for the relationship between mood and anxiety disorders. These disorders are often co-morbid and strongly covary. Other theories and data suggest that personality traits may account, at least in part, for co-morbidity between depression and anxiety. The present study examined the relationship between neuroticism and an internalizing dimension common to mood and anxiety disorders.

METHOD

A sample of ethnically diverse adolescents (n=621) completed self-report and peer-report measures of neuroticism. Participants also completed the Structured Clinical Interview for DSM-IV (SCID).

RESULTS

Structural equation modeling showed that a single internalizing factor was common to lifetime diagnosis of mood and anxiety disorders, and this internalizing factor was strongly correlated with neuroticism. Neuroticism had a stronger correlation with an internalizing factor (r=0.98) than with a substance use factor (r=0.29). Therefore, neuroticism showed both convergent and discriminant validity.

CONCLUSIONS

These results provide further evidence that neuroticism is a necessary factor in structural theories of mood and anxiety disorders. In this study, the correlation between internalizing psychopathology and neuroticism approached 1.0, suggesting that neuroticism may be the core of internalizing psychopathology. Future studies are needed to examine this possibility in other populations, and to replicate our findings.

Multimethod assessment of psychopathy in relation to factors of internalizing and externalizing from the Personality Assessment Inventory: the impact of method variance and suppressor effects

Research to date has revealed divergent relations across factors of psychopathy measures with criteria of internalizing (INT; anxiety, depression) and externalizing (EXT; antisocial behavior, substance use). However, failure to account for method variance and suppressor effects has obscured the consistency of these findings across distinct measures of psychopathy. Using a large correctional sample, the current study employed a multimethod approach to psychopathy assessment (self-report, interview and file review) to explore convergent and discriminant relations between factors of psychopathy measures and latent criteria of INT and EXT derived from the Personality Assessment Inventory (Morey, 2007). Consistent with prediction, scores on the affective-interpersonal factor of psychopathy were negatively associated with INT and negligibly related to EXT, whereas scores on the social deviance factor exhibited positive associations (moderate and large, respectively) with both INT and EXT. Notably, associations were highly comparable across the psychopathy measures when accounting for method variance (in the case of EXT) and when assessing for suppressor effects (in the case of INT). Findings are discussed in terms of implications for clinical assessment and evaluation of the validity of interpretations drawn from scores on psychopathy measures.

All PTSD symptoms are highly associated with general distress: ramifications for the dysphoria symptom cluster

This study used longitudinal data collected from two trauma-exposed samples, survivors of community violence (N = 294) and wildfire evacuees (N = 234), to examine a key claim underlying a proposed reformulation of the symptom structure of posttraumatic stress disorder (PTSD). This theory, which we term the PTSD-dysphoria model, posits that 8 of 17 symptoms of PTSD reflect dysphoria or general psychological distress and might be deemphasized to improve the utility of the PTSD construct (Simms, Watson, & Doebbeling, 2002). For each sample, we analyzed PTSD symptoms and measures of general distress administered at 2 time points. A consistent pattern of findings was observed across assessments for each sample: All 17 PTSD symptoms were highly associated with measures of general distress. Moreover, we found no evidence that dysphoria symptoms were more highly correlated than PTSD-specific symptoms with general distress. Results call into question both the conceptual basis and the clinical utility of differentiating between symptoms that appear to be relatively specific to PTSD and those that seem more broadly characteristic of general psychological distress.

Measuring Context-Specific and Cross-Contextual Components of Hierarchical Constructs

Rating scales are often used to measure behavioral constructs. Yet, different informants' ratings may not necessarily agree. The situational specificity (SS) perspective postulates that discrepancies between ratings by different informants are primarily attributable to contextual behavior of the people being rated. The multitrait-multimethod (MTMM) perspective, however, attributes discrepancies between informants to rater bias, i.e., each informant provides a systematically distorted picture of the person being rated. Similarly, the Attribution-Bias-Context (ABC) perspective also attributes informant discrepancies to systematic biases. Within the context of measuring hierarchical constructs, we proposed a hybrid perspective that takes account of variance attributable to the behavior of the person being rated in a particular context from the perspective of a specific informant. We then provided a parametric representation of this perspective and analyses of mother, teacher, and self-ratings of Rule-Breaking and Aggressive Behavior to illustrate features of the model. Strengths and limitations of the SS, MTMM, and hybrid perspectives are discussed.

Locating eating pathology within an empirical diagnostic taxonomy: evidence from a community-based sample

Existing structural models of psychopathology need to be expanded to include additional diagnostic constructs beyond mood, anxiety, substance use, and antisocial behavior disorders. The goal of this study was to locate eating disorders within a hierarchical structural model of psychopathology that is anchored by broad Internalizing and Externalizing factors. Participants were female adolescent twins (N = 1,434) from the Minnesota Twin Family Study. The authors compared the fit of 4 models in which eating disorders (a) defined their own diagnostic class, (b) represented a subclass within Internalizing, (c) formed a subclass within Externalizing, and (d) were allowed to cross-load on both Internalizing and Externalizing. In the best fitting model, eating disorders formed a subfactor within Internalizing. These findings underscore the value of developing more comprehensive empirically based models of psychopathology to increase researchers' understanding of diverse mental disorders.

The association between earlier age of first drink, disinhibited personality, and externalizing psychopathology in young adults

Earlier age of first drink (AFD) of alcohol is associated with higher rates of alcohol abuse and dependence as well as a range of other externalizing problems. This study tested the hypotheses that in young adults earlier AFD is associated with [1] the common variance among externalizing problems (lifetime alcohol, marijuana, other drug, childhood conduct, and adult antisocial behavior problems) rather than being uniquely associated with alcohol problems, and [2] the disinhibited personality traits of social deviance and impulsivity, and that the association between earlier AFD and externalizing problems is partly accounted for by disinhibited personality. The sample (N=502) included 299 young adults with a history of alcohol dependence (AD) and 203 subjects with no history of AD. Analyses showed that [1] earlier AFD was associated with the covariance among the different domains of externalizing problems and was not unique to any one externalizing problem, [2] earlier AFD was associated with social deviance and impulsivity, and [3] social deviance and impulsivity accounted for part of the association between earlier AFD and externalizing problems. The results suggest that earlier AFD is associated with a vulnerability to disinhibitory disorders and is not specifically associated with alcohol problems.

The genetic epidemiology of personality disorders

Genetic epidemiologic studies indicate that all ten personality disorders (PDs) classified on the DSM-IV axis II are modestly to moderately heritable. Shared environmental and nonadditive genetic factors are of minor or no importance. No sex differences have been identified. Multivariate studies suggest that the extensive comorbidity between the PDs can be explained by three common genetic and environmental risk factors. The genetic factors do not reflect the DSM-IV cluster structure, but rather: i) broad vulnerability to PD pathology or negative emotionality; ii) high impulsivity/low agreeableness; and iii) introversion. Common genetic and environmental liability factors contribute to comorbidity between pairs or clusters of axis I and axis II disorders. Molecular genetic studies of PDs, mostly candidate gene association studies, indicate that genes linked to neurotransmitter pathways, especially in the serotonergic and dopaminergic systems, are involved. Future studies, using newer methods like genome-wide association, might take advantage of the use of endophenotypes.

Sleep disturbance as transdiagnostic: consideration of neurobiological mechanisms

Sleep disturbance is increasingly recognized as an important, but understudied, mechanism in the complex and multi-factorial causation of the symptoms and functional disability associated with psychiatric disorders. This review proposes that it is biologically plausible for sleep disturbance to be mechanistically transdiagnostic. More specifically, we propose that sleep disturbance is aetiologically linked to various forms of psychopathology through: its reciprocal relationship with emotion regulation and its shared/interacting neurobiological substrates in (a) genetics--genes known to be important in the generation and regulation of circadian rhythms have been linked to a range of disorders and (b) dopaminergic and serotonergic function--we review evidence for the interplay between these systems and sleep/circadian biology. The clinical implications include potentially powerful and inexpensive interventions including interventions targeting light exposure, dark exposure, the regulation of social rhythms and the reduction of anxiety. We also consider the possibility of developing a 'transdiagnostic' treatment; one treatment that would reduce sleep disturbance across psychiatric disorders.

Cognitive Functioning and Academic Performance in Elementary School Children with Anxious/Depressed and Withdrawn Symptoms

RATIONALE: Few studies have evaluated the relationship between depressive symptomatology and neuropsychological performance in children without symptomatic depression. OBJECTIVES: This study determined the relationship between anxious/depressed and withdrawn symptoms and performance on cognitive and academic achievement measures. METHODS: 335 Caucasian and Hispanic children aged 6 to 11 years who participated in the Tucson Children's Assessment of Sleep Apnea (TuCASA) study were administered a comprehensive neuropsychological battery measuring cognitive functioning and academic achievement. Their parents completed the Child Behavior Checklist (CBCL). Correlations between performance on the cognitive and academic achievement measures and two Internalizing scales from the CBCL were calculated. Comparisons were made between a "Clinical" referral group (using a T-score of ≥ 60 from the CBCL scales) and a "Normal" group, as well as between Caucasians and Hispanics. RESULTS: No differences were found between those participants with increased anxious/depressed or withdrawn symptoms on the CBCL and those without increased symptoms with respect to age, gender, ethnicity, or parental education level. However, significant negative correlations were found between these symptoms and general intellectual function, language, visual construction skills, attention, processing speed, executive functioning abilities, aspects of learning and memory, psychomotor speed and coordination, and basic academic skills. CONCLUSIONS: These findings support the hypothesis that depressive symptomatology negatively impacts performance on cognitive and academic achievement measures in school-aged children and these findings are not affected by ethnicity. The findings also reinforce the concept that the presence of anxious/depressed or withdrawn symptoms needs to be considered when evaluating poor neuropsychological performance in children.

Consilient research approaches in studying gene x environment interactions in alcohol research

This review article discusses the importance of identifying gene-environment interactions for understanding the etiology and course of alcohol use disorders and related conditions. A number of critical challenges are discussed, including the fact that there is no organizing typology for classifying different types of environmental exposures, many key human environmental risk factors for alcohol dependence have no clear equivalents in other species, much of the genetic variance of alcohol dependence in human is not 'alcohol specific', and the potential range of gene-environment interactions that could be considered is so vast that maintaining statistical control of Type 1 errors is a daunting task. Despite these and other challenges, there appears to be a number of promising approaches that could be taken in order to achieve consilience and ecologically valid translation between human alcohol dependence and animal models. Foremost among these is to distinguish environmental exposures that are thought to have enduring effects on alcohol use motivation (and self-regulation) from situational environmental exposures that facilitate the expression of such motivations but do not, by themselves, have enduring effects. In order to enhance consilience, various domains of human approach motivation should be considered so that relevant environmental exposures can be sampled, as well as the appropriate species to study them in (i.e. where such motivations are ecologically relevant). Foremost among these are social environments, which are central to the initiation and escalation of human alcohol consumption. The value of twin studies, human laboratory studies and pharmacogenetic studies is also highlighted.

Refinements in the hierarchical structure of externalizing psychiatric disorders: Patterns of lifetime liability from mid-adolescence through early adulthood

Research on hierarchical modeling of psychopathology has frequently identified 2 higher order latent factors, internalizing and externalizing. When based on the comorbidity of psychiatric diagnoses, the externalizing domain has usually been modeled as a single latent factor. Multivariate studies of externalizing symptom features, however, suggest multidimensionality. To address this apparent contradiction, confirmatory factor analytic methods and information-theoretic criteria were used to evaluate 4 theoretically plausible measurement models based on lifetime comorbidity patterns of 7 putative externalizing disorders. Diagnostic information was collected at 4 assessment waves from an age-based cohort of 816 persons between the ages of 14 and 33. A 2-factor model that distinguished oppositional behavior disorders (attention-deficit/hyperactivity disorder, oppositional defiant disorder) from social norm violation disorders (conduct disorder, adult antisocial behavior, alcohol use disorder, cannabis use disorder, hard drug use disorder) demonstrated consistently good fit and superior approximating abilities. Analyses of psychosocial outcomes measured at the last assessment wave supported the validity of this 2-factor model. Implications of this research for the theoretical understanding of domain-related disorders and the organization of classification systems are discussed.

Modeling psychopathology structure: a symptom-level analysis of Axis I and II disorders

BACKGROUND

Analyses of co-morbidity patterns among common mental disorders have repeatedly indicated that relationships among disorders can be understood in terms of broad superordinate dimensions. However, these analyses have been based on syndromal-level indicators, which are often heterogeneous, rather than on symptoms, which are presumably more homogeneous.

METHOD

Symptom-level exploratory and confirmatory analyses were used to explore the joint hierarchical organization of Axis I and II psychopathology, using data on 8405 individuals from the 2000 British Psychiatric Morbidity Survey.

RESULTS

Analyses indicated that 20 identified subordinate dimensions of psychopathology could be organized into four broad superordinate dimensions: Internalizing, Externalizing, Thought Disorder, and Pathological Introversion.

CONCLUSIONS

These results extend existing model frameworks 'downward' as well as 'outward', by analyzing symptoms rather than diagnoses, and by integrating symptoms from Axis I and II disorders in a common framework. This model demonstrates the importance of hierarchy in psychopathology structure, comprises replicable features of psychopathology structure, and has important implications for understanding the nature and organization of mental disorders.

The enrichment study of the Minnesota twin family study: increasing the yield of twin families at high risk for externalizing psychopathology

The Enrichment Study (ES) was designed to extend the Minnesota Twin Family Study (MTFS) by oversampling 11-year-old twins at especially high risk for substance use disorders by virtue of having a childhood disruptive disorder. The sample was ascertained from Minnesota birth records. To identify high-risk twins, we conducted telephone screening interviews for parent-reported symptoms of attention-deficit/hyperactivity disorder (ADHD) and conduct disorder (CD) as well as indications of academic disengagement. Twins who exceeded a predetermined threshold were invited to participate. To facilitate comparison with the previously ascertained MTFS participants, a random sample of 11-year-old twins was also recruited. As part of the ES study, 499 twin pairs, and their parents, visited the University of Minnesota, where each participant completed a clinical interview, psychophysiological evaluation, and thorough assessment of environmental risk. We were highly successful in recruiting at-risk twins; 52% of the screened male twins and 41% of the screened females met criteria for a diagnosis of ADHD, CD, or oppositional defiant disorder (ODD). At the pair level, 63% of the screened pairs had at least one member with a childhood disruptive disorder. This article provides an overview of the study design and includes a review of recent findings using this sample of twins.

The structure of common mental disorders: a replication study in a community sample of adolescents and young adults

Previous research suggests that patterns of comorbidity of common mental disorders among adults are best reflected by a hierarchical three-factor structure with two correlated factors ('anxious-misery' and 'fear') summarized in a second-order 'internalizing' factor and one 'externalizing' factor. This three-factor structure has not been examined yet in a sample of adolescents and young adults.A representative sample of 3021 adolescents and young adults (baseline age 14-24) were prospectively followed over 10 years. Mental disorders were assessed according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) by using the standardized Munich Composite International Diagnostic Interview. Ten mental disorders (major depressive episode, dysthymia, generalized anxiety disorder, social phobia, specific phobia, agoraphobia, panic disorder, alcohol dependence, drug dependence, antisocial personality) were fitted to a series of Confirmatory Factor Analysis models using: (1) 12-month data, and (2) lifetime data from a person-year data set.The three-factor model showed good fit to the observed data in our sample both when 12-month diagnoses and lifetime-to-date diagnoses from a person-year data file were used; yet the higher-order 'internalizing' factor summarizing 'anxious misery' and 'fear' had to be omitted.The three-factor model could be replicated in a sample of adolescents and young adults with the exception that the second-order 'internalizing' factor was not consistent with the data. Further research is necessary to provide more complete insight into the structure of mental disorders by examining the stability of the structure of mental disorders in different developmental stages (ages) and by using a more extensive set of mental disorders.

Neurocognitive disorders: cluster 1 of the proposed meta-structure for DSM-V and ICD-11

BACKGROUND

In an effort to group mental disorders on the basis of aetiology, five clusters have been proposed. In this paper, we consider the validity of the first cluster, neurocognitive disorders, within this proposal. These disorders are categorized as 'Dementia, Delirium, and Amnestic and Other Cognitive Disorders' in DSM-IV and 'Organic, including Symptomatic Mental Disorders' in ICD-10.

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 neurocognitive disorders.

RESULTS

'Neurocognitive' replaces the previous terms 'cognitive' and 'organic' used in DSM-IV and ICD-10 respectively as the descriptor for disorders in this cluster. Although cognitive/organic problems are present in other disorders, this cluster distinguishes itself by the demonstrable neural substrate abnormalities and the salience of cognitive symptoms and deficits. Shared biomarkers, co-morbidity and course offer less persuasive evidence for a valid cluster of neurocognitive disorders. The occurrence of these disorders subsequent to normal brain development sets this cluster apart from neurodevelopmental disorders. The aetiology of the disorders is varied, but the neurobiological underpinnings are better understood than for mental disorders in any other cluster.

CONCLUSIONS

Neurocognitive disorders meet some of the salient criteria proposed by the Study Group of the DSM-V Task Force to suggest a classification cluster. Further developments in the aetiopathogenesis of these disorders will enhance the clinical utility of this cluster.

The structure of mental disorders re-examined: is it developmentally stable and robust against additions?

Previous research suggests that patterns of comorbidity of a limited number of anxiety, depressive, substance use and antisocial personality (ASP) disorders among adults are best reflected by a hierarchical three-factor structure with two correlated factors ('anxious-misery' and 'fear') that are summarized in a second-order 'internalizing' factor and one 'externalizing' factor. It has not been examined whether this structure is developmentally stable and robust against additions of more diagnoses. Using data from a prospective-longitudinal community study of adolescents and young adults we re-evaluate the three-factor model originally proposed by Krueger (Archives of General Psychiatry, 1999; 56, 921-926). Using confirmatory factor analysis with identical conventions as in Krueger's original work we found that the three factor model did not fit robustly across age or a wider range of diagnoses. Using explanatory factor analysis we examined alternative structures. We found various clinically meaningful patterns with good fit that go substantially beyond the original three-factor structure. However, again, there is little consistency in findings when different age groups or different diagnoses are considered. Our findings suggest that psychopathology cannot be reduced to any simple structure.

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.

Subthreshold conditions as precursors for full syndrome disorders: a 15-year longitudinal study of multiple diagnostic classes

BACKGROUND

There has been increasing interest in the distinction between subthreshold and full syndrome disorders and specifically whether subthreshold conditions escalate or predict the onset of full syndrome disorders over time. Most of these studies, however, examined whether a single subthreshold condition escalates into the full syndrome form of that disorder. Equally important, though, is whether subthreshold conditions are likely to develop other full syndrome disorders and whether these associations are maintained after adjusting for comorbidity.

METHODS

A 15-year longitudinal study of subthreshold psychiatric conditions was conducted with 1,505 community-drawn young adults. We examined whether 1) subthreshold major depression, bipolar, anxiety disorders, alcohol use, substance use, conduct disorder and/or ADHD were precursors for the corresponding (homotypic) full syndrome disorder; 2) subthreshold conditions were precursors for other (heterotypic) full syndrome disorders; and 3) these homotypic and heterotypic precursors persisted after adjusting for comorbidity.

RESULTS

Subthreshold major depression, anxiety, alcohol use, substance use, and conduct all escalated into their corresponding full syndrome and nearly all homotypic developments were maintained after adjusting for comorbid subthreshold and full syndrome conditions. Many heterotypic associations were also observed and most remained after controlling for comorbidity, particularly among externalizing disorders (e.g., alcohol, substance, conduct/antisocial personality disorder).

CONCLUSIONS

Many subthreshold conditions have predictive validity as they may represent precursors for full syndrome disorders. Alternatively, dimensional conceptualizations of psychopathology which include these more minor conditions may yield greater validity. Subthreshold conditions may represent good targets for preventive interventions.