Externalizing and internalizing subtypes of combat-related PTSD: a replication and extension using the PSY-5 scales.

This study replicated and extended prior findings of internalizing and externalizing subtypes of posttraumatic response (M. W. Miller, J. L. Greif, & A. A. Smith, 2003). Cluster analyses of the Minnesota Multiphasic Personality Inventory--2 Personality Psychopathology--Five (MMPI-2 PSY-5; A. R. Harkness, J. L. McNulty, Y. S. Ben-Porath, 1995) profiles obtained from 736 veterans with posttraumatic stress disorder (PTSD) partitioned the sample into a low pathology cluster defined by personality scores in the normal range, an externalizing cluster characterized by low constraint and high negative emotionality, and an internalizing cluster with high negative emotionality and low positive emotionality. Externalizers showed the highest rates of alcohol-related and antisocial personality disorders; internalizers, the highest rates of panic and major depressive disorder. These findings support the development of a personality-based typology of posttraumatic response designed to account for heterogeneity in the expression of PTSD and associated psychopathology.