The internalizing and externalizing structure of psychiatric comorbidity in combat veterans

Abstract

This study examined the latent structure of psychiatric disorders in a sample with a high prevalence of PTSD. A series of confirmatory factor analyses tested competing models for the covariation between Structured Clinical Interview for DSM-III-R diagnoses among 1,325 Vietnam veterans. The best-fitting solution was a 3-factor model that included two correlated internalizing factors: anxious-misery, defined by PTSD and major depression, and fear, defined by panic disorder/agoraphobia and obsessive-compulsive disorder. The third factor, externalizing, was defined by antisocial personality disorder, alcohol abuse/dependence, and drug abuse/dependence. Both substance-related disorders also showed significant, albeit smaller, cross-loadings on the anxious-misery factor. These findings shed new light on the structure of psychiatric comorbidity in a treatment-seeking sample characterized by high rates of PTSD.

The factor structure of psychiatric comorbidity among Iraq/Afghanistan-era veterans and its relationship to violence, incarceration, suicide attempts, and suicidality

“…Consistent with Hypothesis 1, a three-factor solution similar to one previously identified among male Vietnam veterans (Miller et al, 2008) was found to demonstrate close fit to the data in both samples. As expected, alcohol-use disorders, substance-use disorders, and nicotine dependence loaded onto the externalizing-SUD factor, PTSD and depression loaded onto the distress factor, and panic disorder, social phobia, specific phobia, and OCD loaded onto the fear factor.…”

“…First, given the well-documented relationship between the externalizing-SUD dimension, antisocial personality disorder, and impulsivity problems (e.g., Miller et al, 2008) as well as prior research associating alcoholand substance-use problems with violence among returning veterans (Elbogen et al, 2008;MacManus et al, 2012), it is surprising that violent behavior was not at least modestly associated with the externalizing-SUD dimension; however, as can be seen in Figure 2, when violence was regressed onto both factors, the externalizing-SUD factor had almost no effect on violence (β = 0.03) across samples. Moreover, constraining the path from externalizing-SUD to difficulty controlling violent behavior to be zero did not affect model fit significantly in either sample.…”

“…Other studies have examined how PTSD relates to the higher-order factor structure of psychiatric comorbidity (e.g., Cox et al, 2002;Slade and Watson, 2006;Miller et al, 2008). In general, these studies have found support for a three-factor solution in which PTSD loads exclusively onto the distress factor.…”

Personality Assessment Inventory internalizing and externalizing structure in veterans with posttraumatic stress disorder: Associations with aggression

“…The factors scores were correlated, but only the externalizing factor was uniquely related to self-report of aggression over the past year. Though previous research has provided support for applying an internalizing/externalizing distinction to understanding heterogeneity in the presentation of patients with PTSD (Miller, 2003;Miller et al, 2003Miller et al, , 2004Miller et al, , 2008Miller et al, , 2012, to our knowledge this is the first report to (1) assess the internalizing/externalizing dimensions of posttraumatic stress and associated comorbidity as measured by the PAI and (2) demonstrate the incremental contribution of externalizing psychopathology in the measurement of aggressive behavior.…”

“…While these studies have supported the internalizing/externalizing distinction as a useful heuristic for studying the structure of posttraumatic psychopathology, they are limited by a reliance on cluster-analytic models which are not optimal for examining higher order factor structure of psychopathology thought to be dimensional (Miller, Fogler, Wolf, Kaloupek, & Keane, 2008).…”