Internalizing and externalizing classes in posttraumatic stress disorder: a latent class analysis.

Using latent class analysis (LCA) the typology of personality profiles of veterans with posttraumatic stress disorder (PTSD) was examined based on internalizing/externalizing dimensions of psychopathology. Latent class analysis on Minnesota Multiphasic Personality Inventory-2 (MMPI-2) Personality Psychopathology-5 (PSY-5) scale data from 299 Australian combat veterans with PTSD supported the model, identifying an optimal 4-class solution, with PTSD externalizing class defined by aggressiveness and disconstraint, high and moderate internalizing classes differentiated on the extent of elevations in introversion and negative emotionality and elevation of psychoticism in the high internalizing class and a simple PTSD class with normal range scores. The model was validated using external self-report and psychiatric-interview-derived diagnoses. A second exploratory LCA using broader comorbidity indicators (MMPI-2 Restructured Clinical scales) demonstrated some support for, although limitations in, using nonpersonality measures to identify these classes directly.