Differentiation of depression and PTSD symptoms in combat veterans.

Abstract

tudies have consistently shown that combat veteransevaluated for posttraumatic stress disorder (PTSD) ex-hibit a) extreme and diffuse levels of psychopathologyacross instruments (e.g., Mississippi Scale, Beck De-pression Inventory, Minnesota Multiphasic Personal-ity Inventory [MMPI]), measuring different domainsof mental illness, and b) extreme elevations on the va-lidity scales of the MMPI, which is suggestive of a ‘‘fakebad’’ response style [e.g., Fairbank et al., 1983; Hyer etal., 1986]. Thus, there is a well-documented over-reporting response style among veterans evaluated forPTSD, which hampers evaluation of individual veteransand colors our understanding of the disorder [see Fruehet al., in press, for a comprehensive review of the extantliterature related to this phenomenon].Our understanding of this over-reporting responsestyle among veterans remains undeveloped. For ex-ample, it is not clear to what extent veterans are ableto differentiate their reports of different symptoms(e.g., depression, anxiety) rather than responding witha single global distress factor (e.g., ‘‘negative affect’’).Although previous studies have examined the factorstructure of single PTSD measures [e.g., Engdahl etal., 1996; King and King, 1994; McFall et al., 1990],the distinctiveness of PTSD symptom reports fromother psychiatric symptom domains have not beenstudied in veteran populations.Examination of the psychometric distinctiveness ofdifferent constructs has been attempted with anxietyand depression in a variety of other clinical samples,with mixed results [e.g., Clark et al., 1994], although itappears that greater distinctiveness has been foundwhen homogenous clinical samples were used [e.g.,Cox et al., 1993; Morgan et al., 1998]. Because PTSDis classified as an anxiety disorder and is considered tohave high rates of comorbid depression [e.g., Keaneand Wolfe, 1990], comparison to the anxiety-depres-sion literature is pertinent.The present study was designed to evaluate the psy-chometric distinctiveness of symptom reports of de-pression and PTSD in combat veterans evaluated for