INTRODUCTION
Post-traumatic stress disorder (PTSD) is characterized by the development of specific symptoms following exposure to one or more traumatic events. These include intrusive recollections related to the traumatic event, avoidance of traumarelated stimuli, negative alterations in cognition and mood, and changes in arousal and reactivity, persisting for more than 1 month after the traumatic exposure [1]. PTSD frequently coeISSN 1976-3026 OPEN ACCESS occurs with other psychiatric conditions, with major depressive disorder (MDD) being the most common comorbidity [2]. Epidemiological studies indicate that approximately 50% of individuals with PTSD also meet criteria for depression, particularly among veteran populations [3,4]. Additionally, anxiety disorders, and substance use disorders are frequently observed alongside PTSD, underscoring its complex clinical presentation [5].
Beyond comorbid mood and anxiety symptoms, PTSD is often accompanied by paranoid ideation, impaired reality testing, disorganized thinking, and unusual or bizarre thoughts or behaviors [6]—features typically associated with psychotic or borderline spectrum presentations. The prevalence of psychotic symptoms in patients with PTSD exceeds 30% [5], and some studies have linked the symptoms of PTSD with the negative symptomatology of schizophrenia [7]. For example, individuals with PTSD may experience hypervigilance accompanied by suspiciousness or paranoid beliefs about their environment [8]. Furthermore, chronic PTSD has been associated with personality pathology, including paranoid and schizotypal traits, suggesting that premorbid vulnerabilities may predispose certain individuals to psychotic-like symptoms under stress [9-12].
These phenomenological overlaps raise important questions regarding the origins of such features in PTSD. Do these characteristics reflect premorbid personality vulnerabilities, adaptive responses to trauma, or emerging psychopathology warranting targeted intervention? Clarifying these relationships is clinically significant; as it may refine differential diagnosis, inform individualized treatment strategies, and improve prognostic assessments. Accordingly, a deeper understanding of the personality and psychopathological dimensions of PTSD—beyond its association with depression—may substantially enhance the clinical characterization and management.
The Schizophrenia scale (T_Sc) of the Minnesota Multiphasic Personality Inventory (MMPI) assesses features such as unusual thought processes, social alienation, and interpersonal withdrawal [13]. Previous studies have reported elevated MMPI T_Sc scores in PTSD populations compared with non-PTSD controls. Elahi et al. [14] demonstrated that PTSD and depression in combat veterans predicted elevations in T_Sc. However, little is known about the impact of severe depression and other clinical variables on T_Sc within PTSD populations, particularly among Korean veterans.
In the present study, we retrospectively examined the factors influencing the MMPI-2 T_Sc among patients with PTSD who completed both the Clinician-Administered PTSD Scale (CAPS) and the MMPI-2. Specifically, we investigated whether severe depression in PTSD was associated with elevated T_Sc scores and explored the contributions of personality and psychopathological characteristics.
METHODS
Participants
This study was conducted at the Veterans Health Service Medical Center, which primarily serves national merit awardees and their families. Accordingly, the patient population is largely consisted of individuals exposed to trauma related to military service or participation in the Vietnam War. Among 232 patients who underwent the CAPS assessment between May 2013 and November 2022, those without MMPI-2 data, those with invalid MMPI-2 profiles, and those diagnosed with schizophrenia, delusional disorder, bipolar disorder, delirium, dementia, or mental disorders due to medical conditions, were excluded. All psychiatric diagnoses used for exclusion were made by board-certified psychiatrists based on Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision criteria. Patients with a history of neurological conditions such as head trauma or seizure disorders were also excluded. A total of 119 patients were included in the final analysis (Figure 1). Of these, 64 met criteria for PTSD (CAPS total score ≥20), while 55 were classified as trauma-exposed without PTSD (CAPS <20). Group comparisons between trauma-exposed patients with and without PTSD are presented in Table 1. Within the PTSD group (n=64), patients were further categorized into severe depression group (K-BDI-II ≥29) and non-severe depression group (K-BDI-II <29) for subsequent analyses. This study was a retrospective review of medical records and was approved by the Institutional Review Board of the Veterans Health Service Medical Center (IRB No. 2023-01-009).
Measures
CAPS
The CAPS is a structured clinical interview developed by Blake et al. [15] to assess 17 core PTSD symptoms and 8 associated features of functional impairment. It has been validated in Vietnam War veterans by Weathers et al. [16], demonstrating good reliability and validity, and has also been standardized in the Korean population. In this study, the 1-month reference version of the CAPS was used, which evaluates symp-toms over the preceding month. This study used the DSMIV-based CAPS, which was the standard clinical instrument used during the study period (2013-2022). The total CAPS severity score was used in the analyses; symptom cluster-level analyses were not performed. Following Weathers et al. [16], a total severity score ≥20 was classified as PTSD, while scores <20 were categorized as trauma-exposed without PTSD.
MMPI-2
The MMPI, originally developed by Hathaway and McKinley (1943) [17], is the most widely used objective psychological assessment instrument. The revised version, MMPI-2, modified or removed outdated or biased items, resulting in 567 nonredundant items. While the fundamental structure remains the same as the original MMPI [17], MMPI-2 includes additional validity scales and multiple subscales, such as clinical subscales, restructured clinical (RC) scales, content scales, supplementary scales, and the Personality Psychopathology-Five scales. Raw scores were converted to standardized T-scores (mean=50, SD=10) to facilitate interpretation and comparison across scales. T-scores ≥65 were considered clinically significant with potential psychopathology, personality issues, or significant psychological distress. The T_Sc measures disturbances in thinking, social alienation, and perceptual aberrations, which are the core features of schizophrenia. T_Sc elevation has been found in some patients with depression, partly because the T_Sc scale includes items related to cognitive confusion, bizarre thinking, social alienation, and odd perceptions. Some of these items may overlap with symptoms of severe depression (e.g., cognitive slowing, concentration problems, negative thoughts) in a way that leads to an “artifactual” elevation of T_Sc scores [18,19]. Suzuki et al. [19] reported that MMPI profiles in severe or treatment-resistant depression often show concurrent elevations in depression, psychas-thenia, and T_Sc, reflecting increased cognitive and psychotic-like features or distress. In this study, we used the Korean version of the MMPI-2 (2005 revision) [20], analyzing 10 clinical subscales and 9 RC scales.
Clinical scales
The MMPI clinical scales were developed by Hathaway and McKinley to differentiate psychiatric patients from the general population and to facilitate diagnostic profiling. The 10 scales include Hypochondriasis (Hs, 1), Depression (D, 2), Hysteria (Hy, 3), Psychopathic Deviate (Pd, 4), Masculinity/Femininity (Mf, 5), Paranoia (Pa, 6), Psychasthenia (Pt, 7), Schizophrenia (Sc, 8), Hypomania (Ma, 9), and Social Introversion (Si, 0).
RC scales
The RC scales were developed by Tellegen et al. [21] to address the limitations of original clinical scales, including high intercorrelations and ambiguous item content [22]. By extracting demoralization as a general factor and isolating the unique variance of each scale, the RC scales provide improved interpretability. They 9 RC scales include: Demoralization (RCd), Somatic Complaints (RC1), Low Positive Emotions (RC2), Cynicism (RC3), Antisocial Behavior (RC4), Ideas of Persecution (RC6), Dysfunctional Negative Emotions (RC7), Aberrant Experiences (RC8), and Hypomanic Activation (RC9).
Korean-Beck Depression Inventory-II
The Beck Depression Inventory-II (BDI-II) is a self-report instrument used to screen for depression and consists of 21 questions, rated from 0 to 3 points per question, yielding total scores ranging from 0 to 63. Scores of 14-19 indicate mild depression, 20-28 indicate moderate depression, and 29-63 indicate severe depression [23,24]. The cutoff of Korean-Beck Depression Inventory-II (K-BDI-II) ≥29 was selected based on the validated severity classification of the K-BDI-II, in which scores of 29-63 indicate severe depression [24].
Statistical analysis
All statistical analyses were performed using R (version 4.1.2; R Foundation for Statistical Computing, Vienna, Austria). First, demographic and clinical characteristics were compared between the trauma-exposed individuals without PTSD and the PTSD group (Table 1). Continuous variables are presented as mean±SD, and categorical variables as n (%). Within the PTSD group (n=64), patients with severe depression (K-BDI-II ≥29) were compared with those without severe depression (K-BDI-II <29) using the same procedures (Table 2). In the PTSD group, Pearson’s correlation analysis were performed to examine the associations between the K-BDI-II, CAPS, and MMPI-2 subscales.
To evaluate whether severe depression was independently associated with elevated MMPI-2 T_Sc among patients with PTSD, and to explore the contribution of personality and psychopathological traits, multiple linear regression models were fitted with T_Sc (continuous T-score) as the dependent variable. The primary predictor of interest was severe depression, as defined using the K-BDI-II (coded 1 for K-BDI-II ≥29 and 0 for K-BDI-II <29). Covariates included demographic factors (age and sex), PTSD symptom severity (total CAPS score), and selected MMPI-2 scales (T_Si, T_RCd, and T_RC1). Among psychoticism-related variables (T_Pa, T_Sc, T_RC6, and T_ RC8), the T_Sc score was selected because it captures disturbances in thinking, perceptual aberrations, social alienation, and interpersonal withdrawal, and demonstrated the highest mean T-score in the PTSD group with comorbid severe depression, as well as the strongest correlation with K-BDI-II scores. Confounders were selected based on clinical relevance, prior literature, and correlation analyses, rather than solely on univariate p-values. Within the severely depressed PTSD group, MMPI-2 clinical scales with mean T-scores <65 were excluded from the confounders. A T-score ≥65 was considered a clinically significant elevation, consistent with standard MMPI-2 interpretive guidelines [20]. MMPI-2 variables conceptually overlapping with T_Sc (e.g., T_Pa, T_RC6, and T_RC8) or K-BDI-II (e.g., T_D and RC7) were excluded as confounders. Variables demonstrating multicollinearity (e.g., T_Pt in comparison with T_RCd) were removed. Multicollinearity was assessed using the variance inflation factors (VIF). Independent MMPI-2 variables (e.g., T_Pd) not associated with T_Sc in simple linear regression analyses, were omitted from the final models.
Sequential models were constructed to assess the robustness of the association between severe depression and T_Sc and to examine the incremental contribution of MMPI-2 scales. Model 1 included severe depression only; Model 2 additionally adjusted for age and sex; Model 3 further included CAPS total scores; and Model 4 included T_Si. In Model 5_1, T_ RCd was added to the covariates in Model 4, while in Model 5_2, T_RC1 was added to the covariates in Model 4. Model 6 included all covariates (severe depression, age, sex, CAPS, T_ Si, T_RCd, and T_RC1). Multicollinearity was evaluated using VIFs and was not considered problematic. Regression coefficients (β) with 95% confidence intervals (CI) and p-values were reported. All tests were two-tailed, and a p-value <0.05 was considered statistically significant.
RESULTS
Demographic and clinical characteristics
Table 1 presents the demographic and clinical characteristics of the two groups: trauma-exposed individuals without PTSD and those with PTSD. Patients with PTSD (CAPS ≥20, n=64) demonstrated significantly higher T_Sc scores compared with the trauma-exposed individuals without PTSD (CAPS <20, n=55).
Table 2 summarizes demographic and clinical characteristics of patients with PTSD stratified by depression severity. The mean age of patients with severe depression (K-BDI-II ≥29, n=43) did not differ significantly from that of patients without severe depression (K-BDI-II <29, n=21) at the time of CAPS assessment. However, CAPS scores were significantly higher in the severe depression group (43.26±16.82 vs. 32.10 ±13.30, p=0.004).
Across MMPI-2 scales, the severe depression group exhibited significantly elevated scores on nearly all clinical subscales (e.g., Hypochondriasis, Depression, Psychopathic Deviate, Psychasthenia, and Schizophrenia, all p<0.001; Social Introversion, p<0.05), as well as on most RC scales except T_RC3 (e.g., T_RCd, T_RC1, T_RC6, T_RC7, T_RC8; all p<0.05). In addition, all schizophrenia subscale scores (T_Sc1 - T_Sc6) were significantly associated with severe depression (data not shown on the table).
Correlation analyses
Pearson’s correlation analyses within the PTSD group (Table 3) showed that T_Sc scores were strongly correlated with depressive symptoms (K-BDI-II; r=0.70, p<0.001). Significant correlations were observed across all schizophrenia subscales (T_Sc1 - T_Sc6 ; data not shown on the table). K-BDI-II scores were also strongly correlated with several MMPI-2 scales, in-cluding T_RCd (r=0.70, p<0.001), T_RC1 (r=0.59, p<0.001), and T_Si (r=0.44, p<0.001).
Multiple linear regression analyses
Table 4 presents results from multiple linear regression models examining whether severe depression was independently associated with T_Sc scores among patients with PTSD and how this association changed after adjustment for additional clinical and MMPI-2 variables. In the unadjusted model, severe depression (K-BDI-II ≥29) was strongly associated with elevated T_Sc compared with non-severe depression (Model 1: β=21.79, 95% CI=14.20 to 29.37, p<0.001). This association remained significant after adjustment for age and sex (Model 2: β=20.39, 95% CI=12.55 to 28.22, p<0.001), CAPS scores (Model 3: β=20.44, 95% CI=12.31 to 28.58, p<0.001), and T_ Si scores (Model 4: β=14.00, 95% CI=7.17 to 20.83, p<0.001).
When T_RCd—a RC scale of the MMPI-2—was included (Model 5_1), the effect of severe depression (K-BDI-II ≥29) was no longer significant (β=2.97, 95% CI=-4.00 to 9.95, p=0.397), suggesting that the association between severe depression (K-BDI-II ≥29) and elevated T_Sc was largely explained by general psychological distress indexed by demoralization (T_RCd). In contrast, when T_RC1 was added to Model 4 instead of T_RCd (Model 5_2), severe depression remained significantly associated with T_Sc, although its effect size was attenuated (β=8.19, 95% CI=2.21 to 14.16, p=0.009). In the fully adjusted model (Model 6), T_Si, T_RCd, and T_RC1 remained significantly associated with T_Sc, whereas severe depression was no longer independently associated with T_Sc (Model 6: β=2.11, 95% CI=-4.12 to 8.35, p=0.50).
DISCUSSION
In this study, we investigated whether MMPI-2 T_Sc score is elevated in patients with PTSD and explored the factors contributing to this elevation. Patients with PTSD and comorbid severe depression exhibited significantly higher T_Sc scores than those without severe depression, indicating that depressive symptomatology may initially appear to be a major contributor to elevated T_Sc. However, when additional clinical and personality variables were included in the regression models, the independent effect of depression became insignificant, suggesting that depressive symptoms alone do not fully account for the elevated T_Sc scores observed in PTSD.
Instead, specific MMPI-2 RC scales emerged as stronger predictors. In particular, T_RCd demonstrated the most consistent and robust association with T_Sc. The loss of significance of the K-BDI-II after inclusion of T_RCd, despite the absence of multicollinearity between these variables, indicates that the relationship between T_RCd and T_Sc cannot be fully explained by depressive symptoms alone. This finding suggests that the association between severe depression and T_Sc is largely explained by the construct of T_RCd. Collectively, these results imply that elevated T_Sc scores in patients with PTSD are driven less by the severity of depressive symptoms per se, and more by generalized psychological distress, characterized by a pervasive sense of helplessness and dissatisfaction.
In this sample, patients with PTSD with severe depression (K-BDI-II ≥29) exhibited greater PTSD symptom severity (as measured by CAPS) and marked elevations across all MMPI-2 Schizophrenia subscales (T_Sc1-T_Sc6) compared with those without severe depression. Previous studies have documented high comorbidity rates between PTSD and MDD, possibly due to shared symptomatic, neurobiological, and functional brain mechanisms [3,25], as well as the conceptualization of MDD as a PTSD subtype [3]. A recent meta-analysis of randomized controlled trials further identified comorbid depression as a significant predictor of poorer outcomes in PTSD psychotherapy [26].
The MMPI-2 T_Sc assesses disturbances in thinking, perceptual aberrations, and social alienation, which are core features of schizophrenia. Elevations on this scale were also observed among individuals with severe depression, likely because several T_Sc items capture experiences such as cognitive confusion, unusual perceptions, and social alienation. These features may overlap with severe depressive symptoms (e.g., cognitive slowing, concentration difficulties, and negative selfthoughts), producing an “artifactual” elevation of T_Sc. Suzuki et al. [19] reported that MMPI profiles of depression often include concurrent elevations on Depression, Psychasthenia, Schizophrenia scales, reflecting associations between severe or treatment-resistant depression and cognitive-perceptual disturbances. Furthermore, reduced prefrontal cortex activity observed in both depression and schizophrenia has been linked to cognitive deficits, including impaired concentration and abstract reasoning, which may further explain these overlaps [27]. Accordingly, elevated T_Sc scores observed in severely depressed patients with PTSD may reflect affective-cognitive dysregulation rather than frank psychotic pathology.
Among individuals with schizophrenia-spectrum disorders, the prevalence of comorbid PTSD has been reported to range from 0% to 50%, with many studies indicating rates exceeding 10% [28]. Conversely, elevated MMPI-2 T_Sc scores among patients with PTSD are clinically meaningful but should not be interpreted as indicative of a primary psychotic disorder. In trauma-exposed populations, high T_Sc scores commonly cooccur with elevations in Depression (Scale 2, D) and Psychasthenia (Scale 7, Pt), reflecting broad symptom domains such as dissociation, intrusive experiences, and cognitive disorganization [29-31]. The overlap between PTSD and psychotic symptoms can lead to T_Sc elevations driven by social detachment, cognitive-perceptual distortions, and trauma-related phenomena (e.g., flashbacks, derealization, and transient psychotic-like experiences), rather than true schizophrenia. Several studies have demonstrated that patients with PTSD, even in the absence of comorbid psychotic disorders, frequently exhibit peak elevations on the T_Sc scale, which correlate moderately with PTSD symptom severity [30-32]. In this context, T_ Sc elevation may reflect trauma-related threat sensitivity and social alienation rather than schizophrenia-spectrum psychopathology.
The strong correlations between the T_Sc and BDI-II scores suggest that co-occurring severe depression may amplify traits indexed by the T_Sc scale in patients with PTSD. Regression analyses further demonstrated that severe depression remained a significant predictor of T_Sc until adjustments for additional MMPI-2 scales -particularly demoralization-eliminated that association. The demoralization scale reflects generalized psychological distress characterized by helplessness, hopelessness, and loss of self-confidence rather than disorderspecific symptoms. The present findings indicate that the association between highly depressed patients with PTSD and elevated T_Sc is attributable to demoralization. This means that in patients with PTSD with severe depression, elevated T_Sc scores primarily reflect emotional disorganization, feelings of insecurity, social alienation tendency, and pervasive distress, which may be more accurately captured by the demoralization scale, than genuine psychotic feature. This suggests that global distress and diminished morale may represent a principal pathway through which T_Sc becomes elevated in PTSD patients. Supporting this interpretation, Je et al. [33] reported that veterans with PTSD exhibited marked elevations in MMPI-2 dimensions related to schizophrenialike features, including ideas of persecution, aggressiveness, and psychoticism, compared with trauma-exposed individuals without PTSD. Collectively, these findings bolster the interpretation that high T_Sc scores in individuals with PTSD and severe depression reflect heightened sensitivity to threat and social alienation, rather than frank psychosis.
Overall, these findings suggest that while severe depression is associated with higher T_Sc scores at the group level, the independent determinants of pathological T_Sc elevation reside within specific MMPI-2 RC dimensions. Clinically, this underscores the importance of evaluating demoralization and threat sensitivity when interpreting elevated T_Sc scores in patients with PTSD. Elevated T_Sc values should not be automatically interpreted as evidence of psychotic pathology; rather, they may present state-dependent markers of pervasive distress, social alienation, or trauma-related perceptual distortions. Comprehensive psychometric interpretation may therefore help prevent diagnostic misclassification and support individualized treatment strategies focused on reducing distress and enhancing psychological resilience.
Limitations
This study had some limitations. First, its retrospective, cross-sectional design precludes causal inferences regarding the relationships among depression, demoralization, and T_ Sc elevation. Structured diagnostic interviews for psychotic disorders were not administered, and medication use or ongoing psychiatric treatment was not systematically controlled, which may have influenced both depressive symptoms and MMPI-2 profiles. Second, the exclusive reliance on self-report measures (MMPI-2 and K-BDI-II) introduces the possibility of response biases, such as recall bias, defensiveness or symptom exaggeration. Participants may under-report or over-report symptoms due to social desirability, stigma, recall bias, or limited insight into their own psychological states. In particular, self-reported psychopathology may be influenced by current mood or cognitive distortions, potentially inflating associations among symptom scales. Additionally, although CAPS total scores were included as an index of PTSD severity, symptom cluster-level analyses were not conducted; thus, the differential contributions of specific PTSD symptom domains (e.g., intrusion, dissociation, or hyperarousal) to T_Sc elevation could not be examined. Furthermore, the multivariable regression analyses were based on a relatively modest sample size (n=64), increasing the risk of overfitting and unstable estimates; therefore, these findings should be interpreted as exploratory. The sample consisted predominantly of male Korean veterans, limiting generalizability to civilian or female populations with PTSD, or individuals exposed to non-combat trauma. Additionally, given conceptual overlap among MMPI-2 scales, some observed associations may reflect shared item content rather than distinct psychopathological constructs.
Finally, since no neurocognitive or biological indices were included and longitudinal follow-up data were unavailable, it remains unclear whether elevated T_Sc scores predict clinical outcomes such as treatment response or functional impairment.
Conclusion
Among trauma-exposed individuals assessed using CAPS and MMPI-2, those with PTSD and comorbid severe depression exhibited greater PTSD symptom severity and higher MMPI-2 T_Sc scores. These elevated T_Sc scores appear to reflect intensified social detachment, cognitive-perceptual distortion, and heightened threat sensitivity arising from the interaction between PTSD and severe depression-rather than primary psychosis. Recognizing this complexity has important implications for accurate psychometric interpretation and the tailoring of therapeutic approaches in PTSD populations with comorbid depressive symptoms.
The present findings further indicate that although patients with PTSD frequently show elevated T_Sc scores, particularly in the presence of severe depression, the independent effect of depression diminishes when underlying personality and psychopathological dimensions are considered. Instead, demoralization may be the principal factor driving pathological T_Sc elevation. Clinicians should therefore interpret high T_ Sc scores in patients with PTSD cautiously, considering not only depressive severity but also the broader psychopathological context reflected in the RC scales.
Future research should investigate the prognostic significance of MMPI-2 dimensions in predicting treatment responses and long-term outcomes in individuals with PTSD, ideally using longitudinal, multimodal designs integrating psychometric, neurocognitive, and clinical data.
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