Mark D. Kramer

Linking Antisocial Behavior, Substance Use, and Personality: An Integrative Quantitative Model of the Adult Externalizing Spectrum

Antisocial behavior, substance use, and impulsive and aggressive personality traits often co-occur, forming a coherent spectrum of personality and psychopathology. In the current research, the authors developed a novel quantitative model of this spectrum. Over 3 waves of iterative data collection, 1,787 adult participants selected to represent a range across the externalizing spectrum provided extensive data about specific externalizing behaviors. Statistical methods such as item response theory and semiparametric factor analysis were used to model these data. The model and assessment instrument that emerged from the research shows how externalizing phenomena are organized hierarchically and cover a wide range of individual differences. The authors discuss the utility of this model for framing research on the correlates and the etiology of externalizing phenomena.

Gender differences and developmental change in externalizing disorders from late adolescence to early adulthood: A longitudinal twin study.

Using data from over 1,000 male and female twins participating in the Minnesota Twin Family Study, the authors examined developmental change, gender differences, and genetic and environmental contributions to the symptom levels of four externalizing disorders (adult antisocial behavior, alcohol dependence, nicotine dependence, and drug dependence) from ages 17 to 24. Both men and women increased in symptoms for each externalizing disorder, with men increasing at a greater rate than women, such that a modest gender gap at age 17 widened to a large one at age 24. Additionally, a mean-level gender difference on a latent Externalizing factor could account for the mean-level gender differences for the individual disorders. Biometric analyses revealed increasing genetic variation and heritability for men but a trend toward decreasing genetic variation and increasing environmental effects for women. Results illustrate the importance of gender and developmental context for symptom expression and the utility of structural models to integrate general trends and disorder-specific characteristics.

A construct-network approach to bridging diagnostic and physiological domains: application to assessment of externalizing psychopathology.

A crucial challenge in efforts to link psychological disorders to neural systems, with the aim of developing biologically informed conceptions of such disorders, is the problem of method variance (Campbell & Fiske, 1959). Since even measures of the same construct in differing domains correlate only moderately, it is unsurprising that large sample studies of diagnostic biomarkers yield only modest associations. To address this challenge, a construct-network approach is proposed in which psychometric operationalizations of key neurobehavioral constructs serve as anchors for identifying neural indicators of psychopathology-relevant dispositions, and as vehicles for bridging between domains of clinical problems and neurophysiology. An empirical illustration is provided for the construct of inhibition-disinhibition, which is of central relevance to problems entailing deficient impulse control. Findings demonstrate that: (1) a well-designed psychometric index of trait disinhibition effectively predicts externalizing problems of multiple types, (2) this psychometric measure of disinhibition shows reliable brain response correlates, and (3) psychometric and brain-response indicators can be combined to form a joint psychoneurometric factor that predicts effectively across clinical and physiological domains. As a methodology for bridging between clinical problems and neural systems, the construct-network approach provides a concrete means by which existing conceptions of psychological disorders can accommodate and be reshaped by neurobiological insights.

Optimizing efficiency of psychopathology assessment through quantitative modeling: Development of a brief form of the externalizing spectrum inventory

The Externalizing Spectrum Inventory (ESI; Krueger, Markon, Patrick, Benning, & Kramer, 2007) provides for integrated, hierarchical assessment of a broad range of problem behaviors and traits in the domain of deficient impulse control. The ESI assesses traits and problems in this domain through 23 lower order facet scales organized around 3 higher order dimensions, reflecting general disinhibition, callous aggression, and substance abuse. The full-form ESI contains 415 items, and a shorter form would be useful for questionnaire screening studies or multimethod research protocols. In the current work, we employed item response theory and structural modeling methods to create a 160-item brief form (ESI-BF) that provides for efficient measurement of the ESIs lower order facets and quantification of its higher order dimensions either as scale-based factors or as item-based composites. The ESI-BF is recommended for use in research on psychological or neurobiological correlates of problems such as risk-taking, delinquency, aggression, and substance abuse, and studies of general and specific mechanisms that give rise to problems of these kinds.

Social Causation Versus Social Erosion: Comparisons of Causal Models for Relations Between Support and PTSD Symptoms

Social support is a robust correlate of posttraumatic stress disorder (PTSD) symptoms and of general psychological distress (Ozer, Best, Lipsey, & Weiss, 2003). The nature of the causal relationship between support and PTSD remains the subject of debate, with 2 models, social erosion and social causation, often used to explain findings. Despite extensive research using these models, no studies of which we are aware have included tests of both models within the same series of analyses, across more than 2 time points, in veterans. These competing models were tested in a sample of National Guard soldiers (N = 521) who completed measures of perceived social support and the PTSD Checklist-Military version (Weathers, Litz, Herman, Huska, & Keane, 1993) at 3 months, 15 months, and 27 months following a combat deployment to Iraq. Analyses were run separately for overall PTSD symptoms and the PTSD components of intrusion, trauma-avoidance, dysphoria, and hyperarousal. Both the social erosion (βs ranging from -.10 to -.19) and social causation (βs ranging from -.08 to -.13) hypotheses were supported. Results suggested PTSD-specific symptom dimensions may both erode and be influenced by social support, whereas general psychological distress erodes social support. Implications for clinical intervention and research are discussed.

Development and Preliminary Validation of a Simplified-Wording Form of the Multidimensional Personality Questionnaire

The Multidimensional Personality Questionnaire (MPQ) assesses a range of personality characteristics pertaining to affective and interpersonal style, behavioral restraint versus disinhibition, and capacity for sensory and imaginal engagement. Its 11 lower order trait scales map onto 3 higher order factors that reflect temperament dimensions. Its content and measurement properties have made the MPQ useful for elucidating constructs relevant to normal and abnormal behavior and investigating their neurobiological underpinnings. However, a barrier to its use in certain populations is the reading difficulty of some MPQ items. We describe efforts to develop a simplified-wording form, the MPQ-SF, composed of items readable at or below the seventh grade level (with most below sixth grade). Simplified-wording items demonstrated high convergence with original-wording items, and resulting trait scales showed adequate internal consistencies and appropriate higher order structure. The availability of a simplified version expands the potential utility of the MPQ to a wider range of samples.

Evidence of a prominent genetic basis for associations between psychoneurometric traits and common mental disorders

Threat sensitivity (THT) and weak inhibitory control (or disinhibition; DIS) are trait constructs that relate to multiple types of psychopathology and can be assessed psychoneurometrically (i.e., using self-report and physiological indicators combined). However, to establish that psychoneurometric assessments of THT and DIS index biologically-based liabilities, it is important to clarify the etiologic bases of these variables and their associations with clinical problems. The current work addressed this important issue using data from a sample of identical and fraternal adult twins (N=454). THT was quantified using a scale measure and three physiological indicators of emotional reactivity to visual aversive stimuli. DIS was operationalized using scores on two scale measures combined with two brain indicators from cognitive processing tasks. THT and DIS operationalized in these ways both showed appreciable heritability (0.45, 0.68), and genetic variance in these traits accounted for most of their phenotypic associations with fear, distress, and substance use disorder symptoms. Our findings suggest that, as indices of basic dispositional liabilities for multiple forms of psychopathology with direct links to neurophysiology, psychoneurometric assessments of THT and DIS represent novel and important targets for biologically-oriented research on psychopathology.

Resilience and Posttraumatic Stress Disorder Symptoms in National Guard Soldiers Deployed to Iraq: A Prospective Study of Latent Class Trajectories and Their Predictors

This study examined the prospective course of posttraumatic stress disorder (PTSD) symptoms in a cohort of National Guard soldiers (N = 522) deployed to combat operations in Iraq. Participants were assessed 4 times: 1 month before deployment, 2-3 months after returning from deployment, 1 year later, and 2 years postdeployment. Growth mixture modeling revealed 3 distinct trajectories: low-stable symptoms, resilient, 76.4%; new-onset symptoms, 14.2%; and chronic distress, 9.4%. Relative to the resilient class, membership in both the new-onset symptoms and chronic distress trajectory classes was predicted by negative emotionality/neuroticism, odds ratios (ORs) = 1.09, 95% CI [1.02, 1.17], and OR = 1.22, 95% CI [1.09,1.35], respectively; and combat exposure, OR = 1.07, 95% CI [1.02, 1.12], and OR = 1.12, 95% CI [1.02, 1.24], respectively. Membership in the new-onset trajectory class was predicted by predeployment military preparedness, OR = 0.95, 95% CI [0.91, 0.98], perceived threat during deployment, OR = 1.07, 95% CI [1.03, 1.10], and stressful life events following deployment, OR = 1.44, 95% CI [1.05, 1.96]. Prior deployment to Iraq or Afghanistan, OR = 3.85, 95% CI [1.72, 8.69], predeployment depression, OR = 1.27, 95% CI [1.20, 1.36], and predeployment concerns about a deployments impact on civilian/family life, OR = 1.09, 95% CI [1.02, 1.16], distinguished the chronic distress group relative to the resilient group. Identifying predeployment vulnerability and postdeployment contextual factors provides insight for future efforts to bolster resilience, prevent, and treat posttraumatic symptoms.

Characterizing spouse/partner depression and alcohol problems over the course of military deployment.

Objective: Spouse/partners of military personnel demonstrate elevated levels of distress during military deployments, yet there is insufficient information about courses of adjustment over time. The current study identified trajectories of depression and alcohol use problems and predictors of those trajectories across the deployment cycle. Method: National Guard soldiers (N = 1973) and spouses/intimate partners (N = 1020) completed assessments of risk/protective factors and baseline measures of mental health functioning 2 to 5 months prior to soldiers’ 1-year deployments (Time 1) to Kuwait/Iraq in support of Operation New Dawn or Afghanistan in support of Operation Enduring Freedom. Partners’ mental health was reassessed at 4 months (Time 2) and 8 months (Time 3) after soldiers deployed, and both spouses/partners and soldiers were reassessed 2–3 months postdeployment (Time 4). Results: Latent class growth modeling of partner depression symptoms over time revealed 4 groups: Resilience (79.9%), Deployment Distress (8.9%), Anticipatory Distress (8.4%), and Post-Deployment Distress (2.7%). Three alcohol misuse trajectories were identified: Resilience (91.3%), Deployment Onset (5.4%), and Deployment Desistance (3.3%). Predeployment predictors of partners’ depression symptom trajectories varied by group and included soldier reports of stressors and social support and partner levels of neuroticism, introversion, disconstraint, and reported stressors. Predeployment predictors of alcohol misuse trajectories varied by group, and included soldier levels of alcohol misuse as well as partner neuroticism, disconstraint, and family readiness. Conclusions: Delineating and predicting trajectories of partner adjustment can allow for better targeted interventions toward those most at risk for heightened distress or alcohol problems over the deployment cycle.

Personality traits and combat exposure as predictors of psychopathology over time

BACKGROUND Research suggests that personality traits have both direct and indirect effects on the development of psychological symptoms, with indirect effects mediated by stressful or traumatic events. This study models the direct influence of personality traits on residualized changes in internalizing and externalizing symptoms following a stressful and potentially traumatic deployment, as well as the indirect influence of personality on symptom levels mediated by combat exposure. METHOD We utilized structural equation modeling with a longitudinal prospective study of 522 US National Guard soldiers deployed to Iraq. Analyses were based on self-report measures of personality, combat exposure, and internalizing and externalizing symptoms. RESULTS Both pre-deployment Disconstraint and externalizing symptoms predicted combat exposure, which in turn predicted internalizing and externalizing symptoms. There was a significant indirect effect for pre-deployment externalizing symptoms on post-deployment externalizing via combat exposure (p < 0.01). Negative Emotionality and pre-deployment internalizing symptoms directly predicted post-deployment internalizing symptoms, but both were unrelated to combat exposure. No direct effects of personality on residualized changes in externalizing symptoms were found. CONCLUSIONS Baseline symptom dimensions had significant direct and indirect effects on post-deployment symptoms. Controlling for both pre-exposure personality and symptoms, combat experiences remained positively related to both internalizing and externalizing symptoms. Implications for diagnostic classification are discussed.