Rumination Mediates the Relationship Between Negative Affect and Posttraumatic Stress Disorder Symptoms in Female Interpersonal Trauma Survivors

Abstract

Prior research has identified both rumination and negative affect (NA) as dimensional constructs related to the development and maintenance of posttraumatic stress disorder (PTSD). While both dimensions demonstrate significant positive relationships with symptoms of PTSD, the relationship between the two within the context of the disorder has yet to be explored. Consistent with prior research in the social anxiety literature, the present study seeks to examine a model of mediation by which rumination accounts for the significant relationship between NA and PTSD symptoms. Participants included 65 female interpersonal trauma survivors diagnosed with PTSD using structured, clinician-administered interviews. Both NA and rumination were observed as significant predictors of PTSD symptoms, and the variables were significantly associated with each other. However, NA was no longer a significant predictor of PTSD symptoms when rumination was entered into the mediation model, suggesting full mediation of the relationship by rumination. Results from the current study suggest a complex relationship between NA and rumination in interpersonal trauma survivors with PTSD, such that a ruminative cognitive coping style may either mitigate or exacerbate PTSD symptoms in the presence of sustained negative emotion. The current findings provide support for a cognitive model of PTSD, within which PTSD symptoms are influenced via negative, ruminative cognitions. Primary implications of these results include (a) the consideration of assessment of rumination in interpersonal trauma survivors with PTSD in clinical settings; (b) the selection of treatment that may address a ruminative cognitive style in this population, given the mediation between subjective distress and PTSD symptoms by rumination; and (c) the necessity for the validation of this mediation model within other traumatized populations.

Keywords

PTSD history of child abuse sexual assault

Introduction

The diagnostic criteria for posttraumatic stress disorder (PTSD) underwent significant changes in the most recent iteration of the Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5; American Psychiatric Association [APA], 2013). Notably, a new symptom cluster was added to the diagnostic criteria: “Negative alterations in cognitions and mood associated with the traumatic event(s), beginning after the traumatic event(s) occurred” (APA, 2013, p. 271). A marked alteration from previous diagnostic conceptualizations of PTSD, this new symptom cluster highlights the prominence of persistent negative beliefs, sustained negative emotion, and diminished positive emotion that often accompanies the traditional re-experiencing, avoidance, and hyperarousal symptoms of the disorder. This transition was warranted, as factor analytic research demonstrated more support of the four-factor DSM-5 structure of PTSD in comparison with the three-factor Diagnostic and Statistical Manual of Mental Disorders (4th ed.; DSM-IV; APA, 1994) structure (Elhai & Palmieri, 2011; Friedman, 2013; Friedman, Resick, Bryant, & Brewin, 2011; Hetzel-Riggin & Harbke, 2014). Likewise, empirically supported treatments for PTSD in adults have identified both persistent, distorted negative beliefs and sustained negative emotion as mechanisms for clinically significant symptom reduction in patients with PTSD. Specifically, Cognitive Processing Therapy (CPT; Resick & Schnicke, 1993) attempts to address distorted cognitions that contribute to the maintenance of PTSD, whereas Prolonged Exposure (PE; Foa & Rothbaum, 1998) promotes habituation to sustained negative emotional responses to reminders of the traumatic event.

However, questions remain about the cognitive and emotional constructs inherent within this new symptom cluster, the inter-relationships of these constructs, and how these specific factors contribute to the manifestation and maintenance of PTSD. Two particular constructs related to the negative alterations in cognition and mood symptom cluster that have been independently well-researched within the context of PTSD are rumination and negative affect (NA). Rumination is conceptualized as a cognitive process within which an individual persistently, passively, and repetitively focuses on the causes, meanings, symptoms, and consequences of an emergent psychological disorder (Nolen-Hoeksema, 1991). In the context of PTSD, rumination is conceptualized as persistently, passively, and repetitively focusing on the “trauma and its consequences” (Michael, Halligan, Clark, & Ehlers, 2007). The content of rumination in PTSD is thought to consist of trauma-related negative cognitions that are specific to the symptoms of “persistent and exaggerated negative beliefs or expectations about oneself, others, or the world” and “persistent, distorted cognitions about the cause or consequences of the trauma event(s) that lead the individual to blame himself/herself or others” within the recently added negative alterations in cognition and mood symptom cluster of PTSD (APA, 2013, p. 272). Comparatively, NA is conceptualized as a stable dimension of subjective distress or dysphoria that encompasses temporary and/or sustained negative emotional/mood states including, but not limited to, fear, anger, disgust, guilt, shame, nervousness, sadness, and loneliness (Watson & Clark, 1984). The symptoms of “persistent negative emotional state (e.g., fear, horror, anger, guilt, or shame)” and “feelings of detachment or estrangement from others” reference key aspects of NA (APA, 2013, p. 272). Consistent with the inclusion of these specific symptoms in the diagnostic conceptualization of PTSD, prior research has established both rumination and NA as theoretical risk and maintenance factors of PTSD.

With regard to negative alterations in cognition following a traumatic event, a cognitive model of PTSD (Ehlers & Clark, 2000) proposes that PTSD symptoms are maintained by persistent, excessive negative appraisals of the traumatic event and associated consequences. Rumination is identified as a cognitive processing style that contributes to such appraisals via reinforcement or as a mechanism of cognitive avoidance (Ehlers & Clark, 2000; Michael, Ehlers, Halligan, & Clark, 2005). For example, rumination may allow the individual to avoid directly processing the trauma memory by enhancing focus on irrelevant aspects or hypotheticals. In addition, rumination has been proposed as a specific cognitive vulnerability for the development of PTSD following a traumatic event (Elwood, Hahn, Olatunji, & Williams, 2009).

Consistent with theory and the current diagnostic conceptualization of PTSD, prior research has established rumination as a predictor of PTSD symptoms when assessed both prior to and following a traumatic motor vehicle accident (Ehlers, Mayou, & Bryant, 1998; Ehring, Frank, & Ehlers, 2008; Mayou, Ehlers, & Bryant, 2002). Other research has similarly demonstrated the relationship between rumination and PTSD symptoms in natural disaster survivors (Wu, Zhang, Liu, Zhou, & Wei, 2015; Zhou, Wu, Fu, & An, 2015) and veteran populations (Borders, McAndrew, Quigley, & Chandler, 2012). The relationship between rumination and PTSD symptoms has been observed in survivors of interpersonal assault as well. For example, rumination about intrusive memories was found to be a significant predictor of PTSD symptom severity in a sample of assault survivors (i.e., common assault, actual bodily harm, grievous bodily harm, sexual assault, or rape; Michael et al., 2005). According to the authors, a ruminative response to unwanted, intrusive memories is characterized by “thoughts about how the assault could have been avoided, about the unfairness of the attack, or pondering how life would be better if the trauma had never occurred” (Michael et al., 2005, p. 625). A follow-up analysis of rumination in this sample indicated that certain characteristics of rumination are specifically related to PTSD symptom severity, including the occurrence of hypothetical (i.e., “why,” “what if”) questions, unproductive and compulsive rumination, and the experience of NA both prior to and following rumination (Michael et al., 2007).

Generally, research supports the notion that rumination is a “transdiagnostic process” that is expressed in a similar fashion across many variants of psychopathology, including PTSD and major depression (Birrer & Michael, 2011). Rumination has also demonstrated some qualitative differences in individuals with trauma exposure and/or PTSD in relation to non-traumatized individuals with major depression. For example, rumination typically evokes intrusive memories in traumatized individuals, and, in bi-directional fashion, rumination may be utilized in response to the experience of intrusive symptoms (Birrer & Michael, 2011). Specifically, participants diagnosed with PTSD reported that rumination of internal and external events unrelated to trauma “often or always” triggered unwanted, intrusive memories of past traumatic experiences (Birrer & Michael, 2011, p. 390). Traumatized individuals also demonstrate a tendency to experience more rumination than non-traumatized, depressed counterparts (Birrer & Michael, 2011). Other studies have observed rumination as a potential moderator between PTSD symptoms and depression symptoms (Borders et al., 2012; Roley et al., 2015).

Previous research has used the Ruminative Thought Style (RTS) questionnaire (Brinker & Dozois, 2009) to measure a general tendency to ruminate. This measure eliminates sources of biases observed in other rumination measures, including valence, item content, time-specificity, and overlap with depression (Claycomb, Wang, Sharp, Ractliffe, & Elhai, 2015). A large confirmatory factor analysis using this measure suggested that rumination is multi-dimensional and comprised of four factors: problem-focused thoughts, counterfactual thinking, repetitive thoughts, and anticipatory thoughts (Tanner, Voon, Hasking, & Martin, 2013). Thus, certain phenomenological experiences in individuals with PTSD may relate to a specific factor of rumination. Using confirmatory factor analysis, Claycomb and colleagues (2015) observed that the dysphoria (i.e., NA) and re-experiencing dimensions of PTSD were associated with problem-focused and anticipatory rumination in contrast to counterfactual thinking. Similarly, re-experiencing was associated with anticipatory rumination in contrast to repetitive thinking (Claycomb et al., 2015).

NA has also been identified as a transdiagnostic construct associated with PTSD. Similar to rumination, NA has been proposed as a potential mechanism responsible for the overlap between PTSD and major depression (Brown, Chorpita, & Barlow, 1998; Byllesby, Charak, Durham, Wang, & Elhai, 2016; Mineka, Watson, & Clark, 1998; Post, Zoellner, Youngstrom, & Feeny, 2011). Extensive prior research has established the association between NA and PTSD onset, development, maintenance, and symptom severity among multiple traumatized populations (see Brown et al., 2018, for a brief review). Thus, sustained NA may represent a predisposition for the development of PTSD following a trauma, just as the experience of a trauma and symptoms associated with PTSD may exacerbate the experience of NA, which suggests a transactional relationship between NA, trauma exposure, and subsequent PTSD.

Although the relationship between NA and rumination within PTSD has yet to be empirically explored, it follows that these theoretical constructs are likely closely related. A broad, contemporary review of the relationship between rumination and NA within other clinical and non-clinical populations conducted by Kirkegaard Thomsen (2006) concluded that rumination and multiple NA states (i.e., sadness-depression, anxiety) typically demonstrate significant positive relationships. Persistent rumination likely engenders and sustains NA, whereas temporal or dispositional NA may manifest perseverative cognitive processes, including worry and rumination. Prior research on the relationship between NA and specific cognitive variables in PTSD populations provides preliminary support for the specific examination of NA and rumination. For example, one study observed that negative expectations about mood regulation accounted for differences in the daily experience of NA in veterans with and without PTSD, suggesting an important relationship between general cognitive components of a negative valence and the experience of NA in this population (DiMauro, Renshaw, & Kashdan, 2016). While this study did not focus on the ruminative quality of negative expectations about mood regulation, it is plausible that rumination certainly contributes to the formulation of such expectancies. Another study observed that both NA and anger, assessed independently of NA, mediated the relationship between forgiveness and PTSD (Karaırmak & Güloğlu, 2014). While this study observed the association between a specific emotional state (e.g., anger) and the broad, dispositional construct of NA, it should be noted that rumination increases both depression-related and anger-related affect (Rusting & Nolen-Hoeksema, 1998). Interestingly, Orth, Cahill, Foa, and Maercker (2008) observed that rumination mediates the relationship between PTSD symptoms and anger in a sample of crime survivors, providing further evidence of a complex relationship between PTSD symptoms, NA and associated states, and rumination.

To date, limited research has been conducted examining the relationships among NA, rumination, and PTSD symptoms in female survivors of IPT. Emotional responding seems to differ based on trauma type, and IPT may be more likely to lead to NA than other forms of trauma (Ehring & Quack, 2010). In a college sample, Amstadter and Vernon (2008) found that while all groups reported high levels of emotions during a traumatic event, the IPT survivors reported increased NA after trauma as compared to other trauma survivors. Breslau (2009) found measurement variability due to trauma type, with survivors of IPT more likely to report PTSD symptoms, especially NA. Constant reminders of IPT in the environment, such as news and media coverage, as well as a direct threat on one’s life and continued adversity due to the trauma (such as economic and physical costs) are associated with increased PTSD symptoms, NA, and rumination (Goenjian et al., 2000). IPT in which the survivor felt they should have been able to control the situation (agency) or were hurt by a loved one (betrayal) often lead to self-blame and other intrusive, ruminative thoughts (Freyd, 1994; Webb & Widseth, 2009).

Gender may also have a significant influence on trauma-related outcomes; most research consistently shows that women experience a lifetime prevalence rate of PTSD two times that of men (Brewin, Andrews, & Valentine, 2000; Christiansen & Elklit, 2008; Tolin & Foa, 2006). This may be related to the severity of the trauma. The U.S. Department of Justice (2008) reported that women are more likely to be injured, receive medical treatment, be hospitalized, and lose time from work after a traumatic event. Women seem to perceive traumatic events as more threatening (Yehuda, 2002) and report higher levels of subjective distress than men (Frans, Rimmö, Åberg, & Fredrikson, 2005). Higher rates of PTSD in women may reflect increased vulnerability to emotional distress and ability to form emotional memories (Seidlitz & Diener, 1998). Because of these differences, women tend to ruminate more than men on traumatic memories (Bar-Tal, Lurie, & Glick, 1994). Female IPT survivors are a particularly useful population to examine the relationship among rumination, NA, and PTSD as they consistently show high levels of NA (Badour, Resnick, & Kilpatrick, 2017), rumination (Allbaugh, Wright, & Folger, 2016), and posttraumatic stress symptoms (Hetzel-Riggin & Roby, 2013).

Given limited research on the topic, the present study seeks to examine the relationship between NA, rumination, and posttraumatic stress symptoms in a sample of female interpersonal trauma (IPT) survivors diagnosed with PTSD. While prior research has established a bi-directional, positive association between NA and rumination, rumination is identified as a cognitive avoidance strategy (Birrer & Michael, 2011). Thus, as an individual experiences increased NA, they may engage, deliberately or automatically, in rumination to avoid the associated emotional distress. Within the context of PTSD, rumination may be utilized to similarly avoid the processing of the trauma memory (Foa & Kozak, 1986; Teasdale, 1999). However, this strategy is maladaptive and paradoxical, as dwelling on past negative experiences to avoid immediate emotional distress facilitates the persistence of NA (hence, the bi-directional relationship). Likewise, avoidance of the powerful emotions associated with a trauma memory via rumination may increase PTSD symptoms. The use of rumination is negatively reinforced as an individual cognitively distances themselves from negative emotion, which strengthens fear and subsequent avoidance of negative emotional cues, trauma-related or not. Consistent with this conceptualization of rumination, an individual with PTSD may adopt a ruminative coping style as they experience increased NA. As the use of rumination becomes negatively reinforced, an individual becomes less likely to process their trauma memory, exacerbating their experience of PTSD symptoms. This relationship was observed in a prior study, as rumination mediated the relationship between NA and social anxiety symptoms (Valena & Szentagotái-Tatar, 2015). With consideration of the prior research on NA and rumination in PTSD, and this previously established model of rumination and NA in individuals with social anxiety, it is hypothesized that rumination mediates the relationship between NA and PTSD symptoms, such that increased NA exacerbates PTSD symptoms via increased rumination.

Method

Participants and Procedure

The participants group was comprised of 65 female IPT survivors diagnosed with PTSD who were recruited as part of a larger clinical trial for the treatment of PTSD. Participants were included in the present study if they were female, were aged 18 to 55, had previously experienced IPT(s) (i.e., physical and/or sexual assault, molestation, domestic violence), and met DSM-IV diagnostic criteria for a primary diagnosis of PTSD at the time of the initial clinical assessment. Exclusion criteria consisted of the following: illiteracy, inability to give informed consent, active suicidality, current Axis II diagnosis, current primary alcohol or substance use/dependence disorder, current psychotic spectrum disorder, current bipolar disorder, current involvement in an abusive relationship, current victimization by stalking, and the recent experience of a traumatic event (i.e., within the past month). Other current and/or past comorbid conditions were permitted if PTSD as a result of an IPT was the primary diagnosis.

All procedures were approved by the institutional review board prior to data collection. Recruitment of participants was conducted at a multidisciplinary trauma-focused clinic at a large university in the Midwest as part of a larger, randomized controlled trial for PTSD. After potential participants indicated their interest in the study by contacting the project researchers, they completed a brief phone screening to preliminarily determine their eligibility for the study. Eligible participants then completed the initial, in-person assessment conducted by a trained graduate research assistant. During this initial assessment, the graduate research assistant thoroughly explained the project details to all participants, and informed consent was obtained. Assessment variables of interest included PTSD diagnosis and symptom severity, comorbid psychopathology, negative and positive affect, and frequency of ruminative perseveration.

Measures

Clinician-Administered PTSD Scale for the DSM-IV (CAPS)

The CAPS (Blake et al., 1995) is a clinician-administered, semi-structured diagnostic interview that assesses validity, severity, and improvement of all 17 Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; DSM-IV-TR; APA, 2000) PTSD symptoms over a time period of interest (e.g., past week, past month, lifetime). The CAPS contains separate 5-point (0-4) frequency and intensity rating scales for each PTSD symptom that can be summed for a continuous “severity” total across each individual symptom cluster (i.e., re-experiencing, avoidance, hyperarousal) or all clusters. The CAPS is considered to be the “gold-standard” measure of PTSD symptoms and diagnosis and demonstrates high internal consistency (αs = .92-.99; Blake et al., 1995). Internal consistency of the CAPS, including frequency and intensity ratings of all symptom items, in the present study was sufficient (α = .84). In the current study, the CAPS was used to verify PTSD diagnosis in participants and obtain PTSD symptom severity scores, and only the 1-month and lifetime time periods for each symptom were queried. The past (1-month) month total CAPS score, which reflects current PTSD symptoms, was used in the current analysis. To determine the presence of PTSD symptoms, the original scoring rules (i.e., a minimum frequency score of 1 and minimum intensity score of 2 as requirement for a symptom to be “present”) established by Blake and colleagues (1990) were utilized. Participants were excluded from the analysis if their cumulative CAPS score was below 45, given the increasing likelihood of an improbable PTSD diagnosis (Orr et al., 1997).

Structured Clinical Interview for DSM-IV–Patient version (SCID-IV-P)

The SCID-IV-P is a clinician-administered, structured diagnostic interview that assesses DSM-IV Axis I disorders (First et al., 2002). The interview queries symptoms of each disorder using a categorical system based upon DSM-IV diagnostic criteria. The SCID-IV-P is widely used in both research and clinical settings to verify the presence or absence of psychopathology and demonstrates adequate diagnostic reliability (κ = 0.61-0.83; Lobbestael, Leurgans, & Arntz, 2011) across Axis I conditions in clinical populations. In the present study, the SCID-IV-P was used to identify Axis I conditions comorbid with PTSD and to verify PTSD as the primary Axis I diagnosis.

Positive and Negative Affect Schedule–Expanded form (PANAS-X)

The PANAS-X is a self-report measure comprised of 60 items that assesses dimensions of positive and negative emotion, including affect and emotionality (Watson & Clark, 1994). PA and NA are specifically assessed on the PANAS-X with 10 items each. The 10 items that comprise the NA scale are “afraid, scared, nervous, jittery, irritable, hostile, guilty, ashamed, upset, distressed.” The PANAS-X demonstrates high internal consistency for the PA (α = .83-.90) and NA (α = .85-.90) subscales in both healthy and clinical populations (Watson & Clark, 1994). The NA scale was used in the current study and demonstrated an internal consistency (α = .85) similar to that which was reported in previous research.

RTS questionnaire

The RTS is a 20-item, self-report questionnaire that assesses the frequency of ruminative cognitive perseveration (Brinker & Dozois, 2009). All items are scored on a 7-point Likert-type scale (i.e., 1 = not at all, 7 = very well), yielding a range of total scores from 20 to 140. Higher scores on this measure are indicative of more frequent rumination. The RTS displays high internal consistency (α = .87) and excellent convergent validity with other measures of rumination and perseverative thought (Brinker & Dozois, 2009). Examples of items from the RTS include “When I have a problem, it will gnaw on my mind for a long time,” “I tend to replay past events as I would have liked them to happen,” and “Sometimes I realize I have been sitting and thinking about something for hours.” The RTS was used in the current study as the primary measure of rumination and demonstrated high internal consistency in the current sample (α = .94).

Hamilton Rating Scale for Depression (HAMD)

The HAMD is a clinician-administered, semi-structured diagnostic interview that assesses current symptoms of depression (Hamilton, 1960, 1967). The HAMD contains 17 items, each with either a 3- or 5-point rating scale. The total score for the measure is calculated by summing all individual item scores. Although the HAMD is widely recognized as a well-established, frequently used clinician-administered interview for depression symptoms, prior research has indicated that the internal consistency of HAMD items may vary across clinical populations (α = .46-.92; Bagby, Ryder, Schuller, & Marshall, 2004). Consistent with this research, the HAMD exhibited adequate internal consistency in the present sample (α = .78). The HAMD was selected for use in the present study for methodological consistency in assessment (i.e., clinician-administered) with the CAPS. Obtained total scores were used to control for symptoms of depression in study analyses, given the substantial theoretical overlap between depression symptoms, rumination, and NA.

Data Analysis

All data analyses in the present study were conducted using IBM SPSS Version 24. The proposed mediation model was tested via bootstrapping methodology (10,000 resamples) using the SPSS PROCESS macro designed by Hayes (2013). The PROCESS macro conducts linear regression analyses (when associated variables are continuous) to calculate the magnitude and significance of the direct effects between the independent variable (IV), dependent variable (DV), and mediator. The program also calculates bias-corrected confidence intervals (CI) for indirect effects of the mediation model. It should be noted that significant effects are required between the IV and mediator (referred to as Path a) and the mediator and DV (referred to as Path b) to test for mediation between the IV and DV (referred to as Path c′; Mackinnon, 2008). In the present study, NA represented the IV, PTSD symptom severity represented the DV, and rumination frequency was the mediator. In addition, depression symptom severity was entered into the model as a covariate, given the substantial overlap between depression, rumination, and NA and the prevalence of comorbidity between PTSD and depression symptoms. See Figure 1 for a conceptual model of the mediation analyses conducted in the present study.

Figure 1.

Proposed model for mediation analysis.

Results

Sample characteristics are presented in Table 1. The sample demonstrated a high degree of racial diversity, with 52.3% of participants identifying as Caucasian and the remaining 47.7% of participants identifying as African American and/or other racial minority. The mean age of participants was 31.98 (SD = 9.64) years, and participants, on average, completed 14.89 (SD = 2.44) years of education. The mean NA score of the sample (M = 28.82, SD = 8.17) exceeds that which was reported for psychiatric inpatients and a mixed clinical sample (Watson & Clark, 1994). The same pattern was observed with the mean rumination score of the sample (M = 98.55, SD = 23.82) relative to the adult normative sample (Brinker & Dozois, 2009). The mean CAPS score of the sample (M = 67.89, SD = 17.98) falls in the severe range of PTSD symptomatology (Blake et al., 2000). Similarly, the mean depression score of the sample (M = 13.68, SD = 6.45) falls in the “mild” range of clinical symptomatology (Hamilton, 1967).

Table 1.

Demographic Characteristics of the PTSD Participants Presented as Mean (Standard Deviation) or Number (%).

Characteristic	PTSD (n = 65)
Age (years)	31.98 (9.64)
Gender (female)	65 (100%)
Race (AA, CAU)	22 (33.8%), 34 (52.3%)
Education (years)	14.89 (2.44)
NA Total Score	28.82 (8.17)
RTS Total Score	98.55 (23.82)
CAPS Total Score	67.89 (17.98)
HAMD Total Score	13.68 (6.45)

Note. PTSD = posttraumatic stress disorder; AA = African American; CAU = Caucasian; NA = Negative Affect; RTS = Ruminative Thought Style Questionnaire; CAPS = Clinician-Administered PTSD Scale; HAMD = Hamilton Rating Scale for Depression.

Intercorrelations among study variables are presented in Table 2. Consistent with a mediation analysis, all variables of interest exhibited significant, moderate correlations (p < .001) with each other. The prerequisites for a test for mediation were met, as significant effects were observed for both Path a (i.e., NA → Rumination; β = 1.29, p < .001) and Path b (i.e., Rumination → PTSD symptoms; β = 0.20, p < .05) while controlling for depression symptoms. Path c′ (i.e., NA → PTSD symptoms) also demonstrated a significant effect, total effect = 0.77, SE = 0.28, 95% CI = [0.22, 1.32], p < .01. Consistent with the research hypothesis, full mediation of the relationship between NA and PTSD symptoms by rumination, while controlling for depression symptoms, was observed (indirect effect = 0.258, SE = 0.159, 95% CI = [0.037, 0.668]). As such, Path c′ was no longer significant (p = .09) when accounting for the indirect effect (direct effect = 0.51, SE = 0.30, 95% CI = [–0.08, 1.11]). Full results of the regression analysis are presented in Table 3.

Table 2.

Zero-Order Correlations Among Study Variables.

	1	2	3	4
1. CAPS Total Score	—
2. NA Total Score	.49	—
3. RTS Total Score	.48	.54	—
4. HAMD Total Score	.44	.52	.42	—

Note. CAPS = Clinician-Administered PTSD Scale; NA = Negative Affect; RTS = Ruminative Thought Style Questionnaire; HAMD = Hamilton Rating Scale for Depression.

All correlations between study variables were significant at p < .001.

Table 3.

Mediation Results for the Current Study.

	β	SE	p	95% CI
Path a	1.30	0.36	<.001	[0.58, 2.02]
Path b	0.20	0.10	<.05	[0.01, 0.39]
Path c′ (Total Effect)	0.77	0.28	<.01	[0.22, 1.32]
Path c′ (Direct Effect)	0.51	0.30	.09	[–0.08, 1.11]
Indirect Effect	B = 0.26	0.16		[0.04, 0.68]
Total R²	.33		<.0001

Note. Total HAMD depression symptom score was entered as a covariate for this mediation analysis. CI = confidence interval; HAMD = Hamilton Rating Scale for Depression.

Discussion

Results from the current analysis suggest that rumination may account for the relationship between NA and PTSD symptoms in IPT survivors diagnosed with PTSD. This primary finding is consistent with previous research within which rumination mediated the relationship between NA and symptoms of psychopathology, specifically social anxiety (Valena & Szentagotái-Tatar, 2015). Previous research conducted on these variables in individuals with PTSD has often examined each (i.e., NA and rumination) separately. Results from the current study are consistent with prior analyses such that both NA and rumination demonstrate significant associations with PTSD symptoms. In particular, this study extends prior research on the topic by examining the interaction and clarifying the statistical relationship between the variables. Furthermore, these findings suggest that cognitive coping style may either mitigate or exacerbate PTSD symptoms in the presence of sustained negative emotion.

The current findings provide support for a cognitive model of PTSD, one in which PTSD symptoms are influenced via a ruminative cognitive style (Ehlers & Clark, 2000). Within this model, it is hypothesized that the resulting distress is managed with maladaptive coping strategies, such as rumination. The mediation model in the current study fits the latter half of the proposed model, such that increases in distress (i.e., NA) result in perseverative rumination, which maintains or exacerbates PTSD symptoms. While the present study did not examine cognitive appraisals of the traumatic event as a stimulus for increased distress, future research in this area may seek to do so to further establish support for this model. Given that perseverative rumination may also result in increased distress, which thus reinforces a ruminative cognitive style, it may be worthwhile to consider that rumination may result after any number of stimuli (e.g., re-experiencing symptoms, negative life events) that increase distress in individuals with PTSD.

Despite the clarity provided by the cognitive model of PTSD, rumination is still difficult to conceptualize in relation to the disorder. There are multiple reasons for this issue. First, rumination is defined in multiple ways by different theoretical perspectives. Each perspective may actually assess a different dimension of the multifaceted construct with different instruments (see Smith & Alloy, 2009, for a review). While the specific dimensions of rumination were not examined as potential variables of interest in the current study, the selection of this measure is most consistent with the conceptualization of rumination as a pattern of persistent, passive, and repetitive thought that is independent relative to specific forms of psychopathology. Future studies with access to a larger sample may seek to examine the qualities of rumination as a construct in traumatized samples and the interplay among the factors of rumination within the mediation model proposed by this study. The power of the current analysis does not support the construction of multiple mediation models.

Second, rumination was first conceptualized as a cognitive thought style in individuals with depressed mood (Nolen-Hoeksema, 1991). The mediational analysis in the current study was conducted while controlling for symptoms of depressed mood, given the significant overlap between symptoms of depression and the variables of interest in the study (NA, rumination, PTSD symptoms). Thus, the obtained results were not confounded by this overlap.

Third, within this conceptualization, rumination has been described as an “intrusive” thought process (Claycomb et al., 2015). This issue is a bit more pervasive in the combined literatures on rumination in PTSD and depression. Rumination may be described as “intrusive,” which may be confused with the intrusion symptoms of PTSD as defined by the DSM-5 (e.g., memories, nightmares, flashbacks, emotional and physical distress follow exposure to traumatic reminders; APA, 2013). While rumination and symptoms of intrusion in PTSD are not mutually exclusive, each psychological process is fundamentally different. For example, intrusion symptoms are often experienced spontaneously and are actively avoided, whereas rumination, a deliberate style of cognitive processing, may be utilized habitually and even intentionally. Likewise, each process may have different consequences. A phenomenological analysis of the differences between rumination and intrusive memories in PTSD indicated that rumination was often of longer duration and more strongly associated with shame than intrusive memories (Speckens, Ehlers, Hackmann, Ruths, & Clark, 2007). In addition, sensory experiences were predominant to intrusive memories in comparison with rumination (Speckens et al., 2007). The authors suggest that this distinction may have important implications for treatment—intrusive memories, characterized by sensory experiences, may be better addressed by approaches like in-vivo and imaginal exposure whereas rumination may be better addressed by cognitive restructuring or mindfulness-based techniques (Speckens et al., 2007).

The obtained results from the current study have numerous implications for the conceptualization and treatment of PTSD in female IPT survivors with the disorder. Prior research suggests that emotional consequences of IPT often include shame and guilt, and that both emotions show significant associations with PTSD symptoms (Beck et al., 2011). In addition, rumination tends to be more associated with shame than intrusive memories in individuals with PTSD (Speckens et al., 2007). As such, two valuable inferences can be made: (a) the experience of shame may act as a valuable indicator of rumination in individuals with PTSD, and (b) given that shame is a psychological sequelae often associated with IPT (van der Kolk, Roth, Pelcovitz, Sunday, & Spinazzola, 2005), IPT survivors may be at increased risk for rumination relative to survivors of other types of trauma. As such, it may be useful to assess rumination in IPT survivors presenting for treatment for PTSD.

The results add to the growing literature on how rumination affects the relationship between interpersonal violence and mental health outcomes. While this study is the first to examine rumination as a mediator between NA and PTSD symptoms in IPT survivors, previous research has identified that rumination mediated the relationship between IPT and depression (Padilla Paredes & Calvete, 2014; Zeng, Liu, & Zhong, 2016), borderline personality features (Zielinski, Borders, & Giancola, 2015), and substance use and abuse (Sarin & Nolen-Hoeksema, 2010). Previous research has also identified two subtypes of rumination, brooding and reflection, which have differential effects on the mental health outcomes of IPT survivors. Brooding rumination, as measured in the current study, has mediated the relationship between IPT and depression in emotional abuse survivors (Raes & Hermans, 2008). However, reflective rumination or the “purposeful turning inward to engage in cognitive problem solving” (Treynor, Gonzalez, & Nolen-Hoeksema, 2003, p. 256) has been linked with posttraumatic growth (Stockton, Hunt, & Joseph, 2011). In fact, Taku, Calhoun, Cann, and Tedeschi (2008) found support for a model in which brooding rumination led to increased general mental health distress while reflective rumination led to increased posttraumatic growth. Future research should examine how to identify these patterns in treatment contexts with IPT survivors to enhance reflective rumination and subsequent posttraumatic growth and attenuate brooding rumination. Brooding rumination has shown a positive association with posttraumatic stress symptoms (Wu et al., 2015) and no association with posttraumatic growth (Stockton et al., 2011) among trauma-exposed individuals. Based on these findings, brooding rumination may be a mechanism in the relationship between NA and PTSD symptoms. Reflective rumination may play a role in the connection between NA and posttraumatic growth.

With regard to treatment, results from the current study suggest that addressing rumination in patients may reduce PTSD symptoms. Consistent with recommendations made by Speckens and colleauges (2007), evidence-based treatments for PTSD that address rumination directly, including Mindfulness-Based Cognitive Therapy (Dimidjian, Kleiber, & Segal, 2010) and CPT (Resick & Schnicke, 1993), may prove beneficial for clients who specifically present with a ruminative cognitive style. As increases in distress or NA may trigger a ruminative coping style, some clients, particularly those with less insight or those whom ruminate non-consciously, may first require interventions that address distress tolerance and/or emotion regulation.

There are a few limitations of the current study worth further consideration. First, the sample consisted entirely of female IPT survivors with PTSD. As such, results from the current study may not generalize to male populations, survivors of other types of trauma, or trauma survivors that develop other forms of psychopathology. Second, the current study was part of a larger treatment study for PTSD, and all participants were seeking treatment at the time of participation. These results may not be representative of IPT survivors with PTSD who are not motivated to seek treatment. Third, the sample size of the current study may have limited the power of the analysis to detect very small, yet significant effects. However, the observed power of the study (β = 0.64; calculated using the Monte Carlo Power Analysis for Indirect Effects application developed by Schoemann, Boulton, & Short, 2017) exceeded the guidelines previously recommended for simple mediation models to detect small to moderate effects (e.g., β = 0.45; Fritz & MacKinnon, 2007). Finally, the current study used a cross-sectional design to analyze the relationships between NA, rumination, and PTSD symptoms. Thus, the results should be interpreted with caution with regard to the stability of the observed relationships between these variables over time.

In summary, the present study provides valuable clarification of the relationship between NA, rumination, and PTSD symptoms in IPT survivors with PTSD. Not only does this study replicate a prior finding in the social anxiety literature, but it also provides evidence for a broader model of rumination as a mediator between NA and symptoms associated with various forms of psychopathology. Future research should seek to clarify this relationship further in PTSD, with respect to the examination of the identified subfactors of rumination, and examine this particular model of mediation in other psychological disorders.

Footnotes

Declaration of Conflicting Interests

The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding

The author(s) received no financial support for the research, authorship, and/or publication of this article.

Author Biographies

Wilson J. Brown, PhD, is an assistant professor of clinical psychology at Pennsylvania State University, The Behrend College. His current research interests include (a) the interaction between affect, trauma exposure, and PTSD; (b) the utilization of translational research methodologies to understand emotion regulation in traumatized populations; (c) the improvement of evidence-based treatments for trauma and PTSD; and (d) the effective dissemination of trauma-informed practices and trauma-focused interventions.

Melanie D. Hetzel-Riggin, PhD, is a professor of psychology at Pennsylvania State University, The Behrend College. She is a licensed psychologist and serves as a faculty research associate at the Susan Hirt Hagen Center for Community Outreach, Research, and Evaluation (CORE). Her research focuses on the effectiveness of prevention education to reduce interpersonal violence and peer mistreatment, community-level prevention, and the relationship among interpersonal trauma, coping style, risk and resilience, and mental health outcomes.

Melissa A. Mitchell, PhD, is a licensed clinical psychologist at Summa Health Traumatic Stress Center. Her clinical interests and experience are in the areas of evidence-based treatment for PTSD and anxiety disorders. Her research interests are in the role of rumination and anxiety sensitivity in PTSD.

Steven E. Bruce, PhD, is the director of the Center for Trauma Recovery and associate professor in the Department of Psychological Sciences at the University of Missouri–St. Louis. His research interests and clinical specializations include the treatment of anxiety and affective disorders, particularly post-traumatic stress disorder.

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