JOURNAL OF DUAL DIAGNOSIS, 11(2), 118–127, 2015 C Taylor & Francis Group, LLC Copyright  ISSN: 1550-4263 print / 1550-4271 online DOI: 10.1080/15504263.2015.1025026

Posttraumatic Stress Disorder Symptoms, Emotion Dysregulation, and Aggressive Behavior Among Incarcerated Methamphetamine Users Laura C. Wahlstrom, PhD,1 Jillian Panuzio Scott, PhD,2 Antover P. Tuliao, MA,3 David DiLillo, PhD,3 and Dennis E. McChargue, PhD3

Objective: Methamphetamine use remains a prevalent problem in the United States and is linked to numerous deleterious outcomes, including aggressive behavior, criminal activity, and incarceration. Given these associations, a greater understanding of factors that contribute to aggression among users of methamphetamine is needed, particularly within criminal justice settings, where users of this drug are overrepresented. Methods: The present study examined the relationships between posttraumatic stress disorder (PTSD) symptoms and emotion dysregulation and in-prison physical aggression among incarcerated males who identified as methamphetamine users (N = 60). Results: Participants’ average age was 34.4 years (SD = 7.9), and they were predominantly European American (n = 48, 80%), had spent an average of 6.53 years incarcerated (SD = 4.64), and perpetrated about 1.54 acts of aggression (SD = 6.74) during the past three months. Bivariate correlations found that greater PTSD symptoms (p < .001), greater impulse control difficulties (p < .001), and limited access to emotion regulation strategies (p < .05) were associated with aggression perpetrated in prison. However, results from multiple regression analyses indicated that only PTSD symptoms (p < .001) and nonacceptance of emotional responses (p < .03) were predictive of aggression. Regression analyses also suggested that impulse control difficulties (p < .001), limited access to emotion regulation strategies (p < .04), and nonacceptance of emotional responses (p < .001) interacted with PTSD symptoms to predict increased aggressive behavior. The first interaction ran counter to study hypotheses: At greater levels of PTSD symptoms, those with greater acceptance of emotional responses reported greater aggression perpetration than those with lesser acceptance of emotional responses. The other two interactions were in line with hypotheses, showing that at greater levels of PTSD symptoms, those with greater impulse control difficulties (or lesser access to emotion regulation strategies) reported more aggressive behaviors. Conclusions: Consistent with theories of aggression, study findings suggest that PTSD symptoms bolster the risk of aggression via various forms emotion dysregulation. Results shed light on potential mechanisms that promote in-prison aggression and violent recidivism among this population. (Journal of Dual Diagnosis, 11:118–127, 2015)

Keywords PTSD, methamphetamine, aggression, emotion regulation, incarceration

Methamphetamine is a central nervous system stimulant with a high potential for abuse and dependence (National Institute on Drug Abuse, 2010). Immediate effects of methamphetamine use include euphoria, increased activity, and decreased appetite followed by periods of agitation, irritability, and paranoia, while experiences of chronic methamphetamine users are characterized by violent behavior, anxiety, depression, suicide, and psychosis, as well as legal and environmental problems (Darke, Kaye, McKetin, & Duflou, 2008; Meredith, Jaffe, Ang-Lee, & Saxon, 2005). Empirical investigations reveal that methamphetamine-related 1Central

Texas VA Health Care System, Temple, Texas, USA

2VA Boston Healthcare System and Boston University School of Medicine,

Boston, Massachusetts, USA 3Department of Psychology, University of Nebraska–Lincoln, Lincoln, Nebraska, USA Address correspondence to Dennis E. McChargue, PhD, Department of Psychology, University of Nebraska–Lincoln, 238 Burnett Hall, Lincoln, NE 68588-0308, USA, Email: [email protected] Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/wjdd.

emergency room visits and the percentage of methamphetamine users among individuals in drug treatment have increased between the early 1990s and mid 2000s (Gonzales, Mooney, & Rawson, 2010), further highlighting additional deleterious consequences of the use of this substance. Epidemiological studies of methamphetamine use in the United States suggest that the estimated prevalence of lifetime use ranges from 5% to 8% (Durrell, Kroutil, Crits-Christoph, Barchha, & Van Brunt, 2008; Substance Abuse and Mental Health Services Administration, 2009), with higher rates of use among certain subpopulations, such as individuals who are incarcerated (Department of Justice, 2006; Vik & Ross, 2003). Given the rates of methamphetamine use among prison populations and the association between methamphetamine use and increased risk for incarceration (Milloy, Kerr, Buxton, Montaner, & Wood, 2009), it is not surprising that methamphetamine users are prone to criminal activity, namely aggression and violence (Cartier, Farbee, & Prendergast, 2006). Approximately 39% of state law enforcement officials report that they view methamphetamine as the most problematic drug

PTSD Symptoms, Aggression, and Methamphetamine Use

impacting the criminal justice system (Gonzales et al., 2010). Legal issues related to methamphetamine users are particularly prevalent in the Midwestern United States, where law enforcement reports the greatest number of methamphetamine production lab seizures and second highest rate of methamphetamine use (Weisheit & Wells, 2010). Between 2002 and 2005, several areas of the United States saw a 96% increase in methamphetamine-related arrests (Kyle & Hansell, 2005), and users of methamphetamine who have felony records have poorer drug outcomes than those without felonies (Semple, Zians, Strathdee, & Patterson, 2008). Consistent with its association with criminal activity, methamphetamine users are prone to aggressive behavior (Baskin-Sommers & Sommers, 2006; Zweben et al., 2004). Specifically, one study found that 34.4% of methamphetamine users had engaged in aggressive behavior while under the influence of the drug (Sommers, Baskin, & Baskin-Sommers, 2006), while other findings demonstrate that the majority of methamphetamine users identify it as a contributing factor to their aggression (Brecht & Herbeck, 2013). Former methamphetamine users also show higher rates of aggression than individuals who have not used methamphetamine (Sekine et al., 2006). Given strong associations between methamphetamine use and incarceration (e.g., Milloy et al., 2009), aggression perpetration within the criminal justice system is of particular interest. Evidence from the Census of State and Federal Correctional Facilities found a 23% increase of inmate on inmate violence between 1995 and 2000 (Lahm, 2008). Furthermore, those who have a history of drug use (including methamphetamine) are more likely to engage in prison misconduct (including aggression) than those who do not (Kuanliang & Sorenson, 2008). Despite these associations, there is a gap in research examining the nature of the methamphetamineaggression link among incarcerated individuals. There are several theories regarding aggression, but we found that the I3 theory (Finkel, 2007) had particular utility in providing a framework for intimate partner violence (e.g., Watkins, DiLillo, Hoffman, & Templin, 2015). The I3 theory suggests that three key processes underlie aggression: instigation, impellance, and disinhibition (Finkel, 2007). Instigating factors include those that are relational (i.e., insult from another individual, rejection), displaced (anger induced by a third party), and situational (anger induced by environment). Subsequently, violence perpetration risk is amplified if there are impelling forces that act on the already present instigating factors. Impelling factors are broken down into several categories, including distal (i.e., childhood abuse), dispositional (i.e., anger, dysthymia, testosterone), relational (i.e., poor communication), and situational (i.e., environment). The last factor, disinhibition, includes cultural acceptance of violence, low empathy, poor self-control, and substance use. Disinhibition acts as a threshold, such that if the violent impulses resulting from the interaction between instigating and impelling factors exceed the threshold, an individual is at greatest risk for violence perpetration.

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The present study’s overarching aim was to apply the I3 theory to help explain violence among incarcerated inmates with methamphetamine use histories. Because this theory aids in the interpretation of various contributing factors of violence among prisoners by placing such constructs within a theoretical framework of aggression, we specifically examined impelling forces that are particularly relevant to incarcerated methamphetamine users because of their vulnerability for violence. For instance, posttraumatic stress disorder (PTSD) symptomology is a cluster of symptoms that is highly prevalent among methamphetamine users (Smith, Blumenthal, Badour, & Feldner, 2010). Individuals in prison have higher rates of PTSD than those in the general population (Goff, Rose, Rose, & Purves, 2007). PTSD has also been linked to aggression not only among veterans (e.g., Taft, Vogt, Marshall, Panuzio, & Niles, 2007; Taft et al., 2009) but also in civilian populations (Jakupcak & Tull, 2005; Tull, Jakupcak, Paulson, & Gratz, 2007). Emotion dysregulation is another potential violenceimpelling factor. It is both a characteristic of and distinct from PTSD (Cloitre, Miranda, Stovall-McClough, & Han, 2005; McDermott, Tull, Gratz, Daughters, & Lejuez, 2009). Emotion regulation involves awareness and understanding of emotions, acceptance of emotions, the ability to control impulsive behaviors, and behaving in a manner consistent with desired goals when negative emotions are experienced (Gratz & Roemer, 2004). Methamphetamine users have greater difficulties regulating their emotions than non–methamphetamine users (London et al., 2004). Emotion dysregulation is also related to violence, particularly within the context of romantic relationships. Findings indicate that men who report experiencing difficulties in emotion regulation are more likely to engage in aggressive behavior against a romantic partner (Tager, Good, & Bramer, 2010), presumably in an attempt to regulate their emotional state (Jakupcak, Lisak, & Roemer, 2002). This relationship has also been identified in persons who have experienced a traumatic event (Marshall, Robinson, & Azar, 2011). To our knowledge, research has yet to examine emotion regulation problems with incarcerated individuals who may be prone to violence. Taken together, PTSD symptomology and emotion dysregulation are salient factors within the context of aggressive behavior perpetration and are highly prevalent among methamphetamine users as well as (in some cases) incarcerated individuals. As such, the present study aimed to examine the relationship between PTSD symptomology and emotion dysregulation in predicting aggression perpetration among a sample of incarcerated methamphetamine users. We tested the degree to which greater PTSD symptoms and greater emotion dysregulation (total, as well as specific forms of dysregulation) would each predict greater perpetration of in-prison physical aggression toward other inmates and staff. We also tested whether PTSD symptoms and emotion dysregulation would interact, such that individuals who report higher levels of both risk factors would perpetrate the greatest frequency of aggression. 2015, Volume 11, Number 2

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METHODS Participants and Procedures Male inmates from the Residential Treatment Community (an inpatient drug treatment facility) at the Nebraska State Penitentiary (N = 60) participated in the present study. Participants were an average of 34.4 years old (SD = 7.9 years) and had an average of 11.9 years of formal education (SD = 1.52 years). Participants identified their race/ethnicity as follows: European American (n = 48, 80%), Latino American (n = 5, 8.3%), African American (n = 4, 6.7%), and Native American (n = 3, 5.0%). Table 1 presents other demographic statistics pertinent to this study. The criterion for inclusion was for participants to selfidentify methamphetamine as their drug of choice. The Institutional Review Board at the University of NebraskaLincoln as well as Nebraska State Penitentiary approved this study. All participants gave written informed consent for data to be collected from a larger battery of individually investigator-administered and self-report measures, as well as for archival data to be collected from residential treatment files and from the Nebraska Department of Correctional Services’ online records. Individuals were not compensated for participation.

Measures PTSD Checklist–Civilian Version (PCL-C) The PCL-C (Weathers, Litz, Herman, Huska, & Keane, 1993) consists of 17 items assessing posttraumatic stress disorder symptomology experienced during the past month. Responses are given on a 5-point Likert-type scale, ranging from 1 (not at all) to 5 (extremely). Total scores range from 17 to 85, and higher scores indicate the severity of PTSD symptoms experienced. The PCL-C has demonstrated good internal consistency and test-retest reliability (Blanchard, Jones-Alexander, Buckley, & Forneris, 1996; Weathers et al., 1993). The internal consistency reliability estimate for the PCL in the current sample was .91.

Difficulties in Emotion Regulation Scales (DERS) The DERS (Gratz & Roemer, 2004) consists of 36 items assessing emotion dysregulation. Each item is answered on a 5point Likert-type rating scale that ranges from 1 (almost never) to 5 (almost always). Higher scores indicate greater emotion dysregulation. The DERS items comprise a total score and six subscales: nonacceptance of negative emotions (e.g., When I’m upset, I become angry with myself for feeling that way), Journal of Dual Diagnosis

difficulties controlling impulsive behaviors when experiencing negative emotions (e.g., When I’m upset, I become out of control), limited access to emotion regulation strategies perceived to be effective (e.g., When I’m upset, I believe that I will remain that way for a long time), lack of emotional awareness (e.g., When I’m upset, I take time to figure out what I’m really feeling), and lack of emotional clarity (e.g., I have difficulty making sense out of my feelings). The DERS has been shown to have adequate internal consistency and test-retest reliability (Gratz & Roemer, 2004). The internal consistency reliability estimate for the DERS total score in the current sample was .92; alpha coefficients for the DERS subscales ranged from .51 to .87.

Modified Revised Conflict Tactic Scales (CTS2) The CTS2 Physical Assault subscale (Straus, Hamby, Boney-McCoy, & Sugarman, 1996) consists of 12 items designed to assess intimate partner violence. For the present study, one modification was made to the CTS2 in order to assess physical aggression perpetrated against fellow inmates and staff during the 3 months prior to assessment rather than aggression perpetrated against an intimate partner. This subscale includes behaviors that reflect minor physical aggression (e.g., I threw something at someone that could hurt; I pushed or shoved someone), as well as those that reflect severe physical aggression (e.g., I choked someone; I kicked someone). Participants indicate the frequency at which they perpetrated each behavior using a 7-point scale ranging from 0 (never) to 6 (more than 20 times). Responses to each of the 12 items are summed to produce a total aggression perpetration score. Higher scores indicate higher frequency and more aggressive behaviors perpetrated. Alpha coefficient for this study was .88.

Data Analysis Plan To test the hypothesis that greater PTSD symptoms and greater emotion dysregulation (total, as well as each specific form of dysregulation) would each predict greater perpetration of inprison physical aggression toward other inmates and staff, bivariate correlations were computed among PCL scores, DERS total and subscale scores, and Modified CTS2 scores. Correlations were interpreted according to statistical significance and Cohen’s (1988) suggestions for effect size interpretation (i.e., a coefficient of 0.1 to 0.3 represents a small effect size, 0.3 to 0.5 represents a moderate effect size, and greater than 0.5 represents a large effect size). To test the second hypothesis, that various forms of emotion dysregulation would moderate associations between PTSD symptoms and aggression perpetration such that the effects of PTSD symptoms on aggression perpetration would be potentiated by greater emotion dysreg-

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TABLE 1 Participant Characteristics and Descriptive Statistics for Study Variables (N = 60) Variable

M

Lifetime alcohol/drug usea Alcohol Cannabis Cocaine Hallucinogens Inhalants Sedative Heroin Methadone Other opiates Barbiturates Years of methamphetamine use Years of polysubstance use History of arrests and offenseb Nonviolent offense only Violent offense only Both violent and nonviolent Years incarcerated (jail and prison) PTSD symptoms Emotion dysregulation total Nonacceptance of emotional responses Difficulties with goal-directed behavior Impulse control difficulties Lack of emotional awareness Limited access to emotion regulation Lack of emotional clarity Aggression perpetration (past 3 months)

SD

Mdn

n (%)

Range

37 (88%) 35 (83%) 32 (76%) 19 (45%) 8 (19%) 7 (17%) 6 (14%) 6 (14%) 5 (12%) 5 (12%) 9.46 10.48

7.62 8.67

9.00 9.50

1 – 29 1 – 29 17 (43%) 0 (0%) 23 (57%)

6.53 36.46 86.67 12.31 14.48 12.20 16.00 15.30 10.25 1.54

4.64 11.45 13.48 4.33 3.01 5.18 4.49 5.46 3.29 6.74

6.00 34.00 77.00 11.50 14.00 10.50 17.00 14.00 10.00 0.00

1 – 26 19 – 72 62 – 148 6 – 27 7 – 21 6 – 30 7 – 26 8 – 38 5 – 19 0 – 46

Note. PTSD = posttraumatic stress disorder; Mdn = median. aIn addition to methamphetamine (all participants used methamphetamine). No alcohol/drug use data were available for 18 participants; n = 42. bNonviolent offenses included drug-related crimes, weapons-related crimes, burglary, arson, prostitution, shoplifting, and vandalism. Violent offenses included homicide, assault, rape, and robbery. No data were available for 20 participants; n = 40.

ulation, we conducted a series of multiple regression analyses. PCL scores and DERS total and subscale scores were centered at the mean (i.e., raw score – mean score) of each variable prior to analysis to reduce the correlation between the interaction term and its component variables and to increase the ease of interpretation (Aiken & West, 1991). Seven interaction terms, between PCL scores and DERS total and subscale scores, were computed. Then, seven multiple regression analyses were conducted (one for each of the DERS subscale scores, plus the DERS total score). In each of these regressions, the centered version of the DERS total or subscale score, the centered version of the PCL score, and the interaction term, were entered as independent variables, and Modified CTS2 scores were entered as the dependent variable.

dicating possible PTSD diagnosis among civilians (McDonald & Calhoun, 2010), as well as scores among individuals seeking substance use treatment (Tull, Gratz, Aklin, & Lejuez, 2010). Emotion dysregulation subscales scores on the DERS were similar to or slightly higher than those reported among undergraduate student samples (Cohn, Jakupcak, Seibert, Hildebrandt, & Zeichner, 2010; Gratz & Roemer, 2004) and similar to or slightly lower than those reported among clinical samples (Ehring & Quack, 2010; Tager et al., 2010). Approximately 17% (n = 10) of participants reported perpetrating aggression in the three months prior to assessment, and the sample endorsed approximately 1.5 (SD = 6.74) acts of aggression during this time period. Table 2 presents the various aggressive behaviors and the number of participants endorsing each one.

RESULTS Descriptive Statistics Table 1 presents the descriptive statistics for all study variables. Participants’ mean score on the PCL-C was 36.46 (SD = 11.45), which is slightly below commonly used cutoffs in-

Relationship Between PTSD Symptoms and Emotion Dysregulation and Aggression Perpetration To test the hypothesis that greater PTSD symptoms and greater emotion dysregulation (total, as well as each specific form 2015, Volume 11, Number 2

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TABLE 2 Frequency of Aggressive Behavior Reported (N = 60)

Beating up Using a knife or gun Choking Grabbing Throwing something that could hurt Pushing or shoving Slamming against a wall Kick, bite, or punch Slapping Hitting with something Twisting arm or hair Burning or scalding

n

%

6 4 3 3 3 3 2 2 2 1 1 1

10.00% 6.67% 5.00% 5.00% 5.00% 5.00% 3.33% 3.33% 3.33% 1.67% 1.67% 1.67%

Interactions Between PTSD Symptoms and Emotion Dysregulation in Predicting Aggression Perpetration Table 4 presents the results from multiple regression analyses testing the second study hypothesis: that various forms of emotion dysregulation would moderate associations between PTSD symptoms and aggression perpetration such that the effects of PTSD symptoms on aggression perpetration would be potentiated by greater emotion dysregulation. These regression analyses each accounted for between 30% and 53% of the variance in aggression perpetration. Several significant main effects were noted. In each analysis, with the exception of the regression including difficulties in impulse control (p < .08), greater PTSD symptoms were a significant predictor of greater aggression perpetration (p < .001), consistent with study hypotheses. Also consistent with study hypotheses, greater nonacceptance of emotional responses was predictive of greater aggression perpetration (p < .03). Of the seven possible interactions with PTSD symptoms, three were statistically significant: nonacceptance of emotional responses (p < .001), impulse control difficulties (p < .001), and limited access to emotion regulation (p < .04). These interactions were graphed using Interaction, a software program designed to test moderation (Soper, 2009), to depict the results. As shown in Figure 1, the relationship between PTSD symptoms and aggression perpetration was moderated by nonacceptance of emotional responses. Specifically, counter to hypotheses, at greater levels of PTSD symptoms, participants with greater acceptance of emotional responses reported greater aggression perpetration than participants with lesser acceptance of emotional responses, B = -0.03, SE = 0.01, t (54) = -2.91, p < .001. As depicted in Figure 2 and consistent with hypotheses, the relationship between PTSD symptoms and aggression perpetration was moderated by impulse control difficulties such that at higher levels of PTSD symptoms, participants with greater impulse control

of dysregulation) would each predict greater aggression perpetration, bivariate correlations among study variables were computed. These correlations are presented in Table 3. Consistent with hypotheses, aggression perpetration was positively associated with PTSD symptoms, r (58) = .49, p < .001, representing a moderate effect. Also consistent with hypotheses, moderate effects were found for the association between aggression perpetration and impulse control difficulties, r (59) = .46, p < .001, and the association between aggression perpetration and limited access to emotion regulation strategies, r (58) = .32, p < .05. Contrary to hypotheses, total emotion dysregulation, nonacceptance of emotional responses, difficulties engaging in goal-directed behavior, lack of emotional awareness, and lack of emotional clarity were not significantly associated with aggression perpetration, though the correlation between total emotion dysregulation and aggression perpetration, r (58) = .22, ns, represented a small-to-medium effect size.

TABLE 3 Intercorrelations Among Study Variables Variables

1.

2.

1. PTSD symptoms 2. Emotion dysregulation total 3. Nonacceptance of emotional responses 4. Difficulties engaging in goal-directed behavior 5. Impulse control difficulties 6. Lack of emotional awareness 7. Limited access to emotion regulation strategies 8. Lack of emotional clarity 9. Aggression perpetration

– .66∗∗∗ .32∗ .25

– .57∗∗∗ .47∗∗∗

– .31∗

–

.61∗∗∗ .29∗ .65∗∗∗

.78∗∗∗ .60∗∗∗ .88∗∗∗

.20 .11 .47∗∗∗

.51∗∗∗ .49∗∗∗

.76∗∗∗ .22

Note. PTSD = posttraumatic stress disorder. ∗ p < .05, ∗∗ p < .01; ∗∗∗ p < .001.

Journal of Dual Diagnosis

3.

4.

.30∗ −.16

5.

6.

7.

.26∗ .13 .25

– .31∗ .76∗∗∗

– .34∗∗

–

.33∗∗ .02

.47∗∗∗ .46∗∗∗

.57∗∗∗ .06

.56∗∗∗ .32∗

8.

9.

– .11

–

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TABLE 4 Multiple Regression Analyses Predicting Aggression Perpetration from PTSD Symptoms and Emotion Dysregulation Predictor

B

SE

t

p

PTSD symptoms Emotion dysregulation total PTSD symptoms × emotion dysregulation total R2= 0.31, F (3, 54) = 8.26, p < .001

0.37 −0.11 0.00

0.10 0.06 0.00

3.59 −1.91 1.66

.001 .06 .10

PTSD symptoms Nonacceptance of emotional responses PTSD symptoms × nonacceptance of emotional responses R2 = 0.44, F (3, 54) = 14.29, p < .001

0.37 −0.38 −0.03

0.07 0.17 0.01

5.60 −2.19 −2.91

.001 .03 .001

PTSD symptoms Difficulties engaging in goal directed behavior PTSD symptoms × difficulties engaging in goal directed behavior R2 = 0.30, F (3, 54) = 7.53, p < .001

0.28 −0.47 0.04

0.08 0.29 0.02

3.49 −1.63 1.69

.001 .11 .10

PTSD symptoms Impulse control difficulties PTSD symptoms × impulse control difficulties R2 = 0.53, F (3, 54) = 20.63, p < .001

0.14 −0.19 0.04

0.08 0.19 0.01

1.78 −1.01 5.49

.08 .31 .001

PTSD symptoms Lack of emotional awareness PTSD symptoms × lack of emotional awareness R2 = 0.28, F (3, 54) = 6.94, p < .001

0.31 −0.15 0.02

0.08 0.19 0.02

4.02 −0.79 1.28

.001 .43 .21

PTSD symptoms Limited access to emotion regulation strategies PTSD symptoms × limited access to emotion regulation strategies R2 = 0.30, F (3, 54) = 7.83, p < .001

0.29 −0.26 0.02

0.10 0.22 0.01

2.93 −1.21 2.13

.001 .23 .04

PTSD symptoms Lack of emotional clarity PTSD symptoms × lack of emotional clarity R2 = 0.28, F (3, 54) = 7.16, p < .001

0.35 −0.46 0.01

0.09 0.28 0.02

3.81 −1.66 0.63

.001 .10 .53

Note. B = unstandardized regression coefficient; SE = standard error; PTSD = posttraumatic stress disorder.

difficulties reported greater aggression perpetration, B = 0.04, SE = 0.01, t (54) = 5.49, p < .001. Last, as shown in Figure 3, the relationship between PTSD symptoms and aggression perpetration was moderated by limited access to emotion regulation strategies. Specifically, consistent with hypotheses, participants with lesser access to emotion regulation strategies reported greater aggression perpetration at higher levels of PTSD symptoms than participants with greater access to emotion regulation strategies, B = 0.02, SE = 0.01, t (54) = 2.13, p < .05.

DISCUSSION Using the I3 theory as a conceptual springboard, we aimed to examine the relationships among PTSD symptoms, emotion dysregulation, and aggression in incarcerated methamphetamine users. Bivariate analyses suggested that aggression was associated with PTSD symptoms, impulse control difficulties, and limited access to emotion regulation strategies. On the other hand, multivariate analyses suggested that only PTSD symptoms and nonacceptance of emotional responses

predicted self-reported aggressive behaviors. Interaction effects suggested that PTSD symptoms interacted with impulse control difficulties, limited access to emotion regulation strategies, and nonacceptance of emotional responses to predict aggressive behavior among incarcerated methamphetamine users. Consistent with our hypothesis, results indicated that greater PTSD symptoms were associated with higher rates of aggressive behavior during incarceration. Findings linking PTSD symptoms and aggressive behavior are consistent with those found among veteran and civilian samples (Marshall, Panuzio, & Taft, 2005; Orcutt, King, & King, 2003; Rosenbaum & Leisring, 2003; Taft et al., 2007). Furthermore, the results of this study address a gap in the literature for forensic adult populations. A systematic review revealed a dearth of research on PTSD among adult prisoners (Goff et al., 2007) and other research has concluded that most of what we know about the relationship between PTSD and offending behavior in a forensic setting is limited to juveniles (Ardino, 2012). From an I3 perspective, PTSD symptomatology functions as a violence impelling factor, particularly through anger and hostility (Finkel, 2007). Prior research suggests a strong

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FIGURE 1 Interaction between PTSD symptoms and nonacceptance of emotional responses in predicting aggression perpetration; B = -0.03, SE = 0.01, t (54) = −2.91, p < .001.

FIGURE 2 Interaction between PTSD symptoms and impulse control difficulties in predicting aggression perpetration; B = 0.04, SE = 0.01, t (54) = 5.49, p < .001.

FIGURE 3 Interaction between PTSD symptoms and limited access to emotion regulation strategies in predicting aggression perpetration; B = 0.02, SE = 0.01, t (54) = 2.13, p < .05.

Journal of Dual Diagnosis

relationship between anger/hostility and PTSD over and above that accounted for by the PTSD diagnostic criteria (Orth & Weiland, 2006). One hypothesis, the fear avoidance theory (Feeny, Zoellner, & Foa, 2000), posits that individuals with PTSD tend to avoid trauma-related fear that is brought about by trauma-related intrusive thoughts. Instead of fear, individuals with PTSD have a tendency to focus on trauma-related anger, which is more positively valenced. On the other hand, the survival mode theory suggests that individuals with PTSD symptoms are primed for a fight-or-flight or “survival” mode, and their thresholds for experiencing both fear and anger are much lower than their peers (Chemtob, Novaco, Hamada, Gross, & Smith, 1997). Theoretical considerations notwithstanding, the elevated anger and hostility found in individuals with PTSD symptomatology could serve as the impelling factor that could lead to subsequent aggression. In addition to PTSD symptomatology, the effects of methamphetamine abuse and withdrawal could also act as violence impelling factors. Chronic methamphetamine abuse is associated with the presence of positive psychotic symptoms, particularly paranoia (Dawe, Davis, Lapworth, & McKetin, 2009), which could further compound the fight-or-flight predisposition of individuals with elevated levels of PTSD symptomatology (Chemtob et al., 1997). Methamphetamine withdrawal is also associated with elevated levels of depression (Zorick et al., 2010), which the I3 theory posits as a violence-impelling factor. Global emotion dysregulation, as well as some of its subcomponents (i.e., lack of emotional clarity and emotional awareness, difficulties engaging in goal directed behaviors), was not associated with aggressive behavior when controlling for PTSD symptomatology. Bivariate analyses suggest that only impulse control difficulties and lack of emotional strategies were associated with self-reported aggressive behavior. Our results are contrary to prior research suggesting that emotion dysregulation, including alexithymia, is elevated among methamphetamine users (London et al., 2004) and among those with PTSD (Frewen, Dozois, Neufeld, & Lanius, 2008). This finding may suggest that subcomponents of emotion dysregulation better explain its relationship with aggressive behavior, particularly with concurrent PTSD symptomatology. Taken together with other research, our results also suggest that emotion dysregulation subcomponents relate to aggression differentially across populations. For instance, contrary to our results, lack of emotional clarity and emotional awareness were associated with aggression in an undergraduate male population (Cohn et al., 2010). Although difficulties with identifying emotions were associated with expressed anger among methamphetamine users in previous studies (Payer, Lieberman, & London, 2011), we did not find support for these findings in the present investigation. The elevation in anger and hostility among individuals with PTSD symptomatology is insufficient to account for the subsequent aggressive behavior, and our study suggests that PTSD symptomatology interacts with disinhibition, or impulsivity-related emotion dysregulation to influence aggres-

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sion. Specifically, limited access to emotional regulation strategies and impulse control difficulties were associated with more aggressive behavior among inmates with greater PTSD symptoms. These results are consistent with the I3 theory, such that inhibition, impulse control difficulties, and access to emotion regulation strategies are important moderators between violence-instigating and -impelling factors and subsequent aggression. Our results are consistent with, and add to, other studies implicating impulsivity in other externalizing problem behaviors, including suicide (Kotler, Beersheba, Iancu, Efroni, & Amir, 2001) and substance abuse (Marshall-Berenz, Vujanovic, & MacPherson, 2011), among individuals with PTSD or trauma histories. The literature also suggests that chronic methamphetamine use exacerbates impulse control problems and aggression (Dawe et al., 2009). For example, stimulant use has been found to predict aggression over and above that variance accounted for by trait impulsivity and antisocial personality (Stuart, Temple, Follansbee, Bucossi, Hellmuth, & Moore, 2008). Apart from impulsivity-related emotion dysregulation, nonacceptance of emotional responses interacts with PTSD symptoms to predict aggression. That is, incarcerated methamphetamine users who are more accepting of their emotions and with greater PTSD symptoms were more likely to report more violent behaviors compared to individuals with fewer PTSD symptoms and lower acceptance of emotional responses. Although these findings are contrary to our hypothesis, they are relatively consistent with the fear avoidance hypothesis (Feeny et al., 2000; Foa, Riggs, Dancu, & Rothbaum, 1995). As previously mentioned, inmates may more readily experience anger and hostility as well as engage in aggressive behavior in order to manage unwanted trauma symptomology. Some evidence suggests that engaging in violent acts may provide short-term relief from PTSD symptoms (Weierstall, Schaal, Schalinski, Dusingizemungu, & Elbert, 2011). In summary, results of the present study suggest the PTSD symptoms and certain subcomponents of emotion dysregulation are associated with aggressive behavior among incarcerated methamphetamine users. Consistent with I3 theory, PTSD symptomatology functions as a violence-impelling factor, moderated by impulsivity-related emotion dysregulation, to influence aggression perpetration. The results presented here, however, should be tempered by the limitations. The small sample size and the inclusion of only male incarcerated non–treatment-seeking participants (majority of whom are of European descent) limits the statistical power and generalizability of the study. Furthermore, the correlational and cross-sectional design makes it difficult to ascertain the nature and direction of the relationship among the variables. Given the saliency of impulse control problems in this population, only a longitudinal design may help disentangle the effects of chronic methamphetamine use on aggression independent from those accounted by dispositional impulsivity. This article also focuses on the severity of PTSD symptoms rather than the presence of PTSD, which requires that the symptoms be

linked to a specific traumatic event (Criterion A) for diagnosis. Finally, future research can also improve upon the DERS’s psychometric properties given the low internal consistency observed in this study.

ACKNOWLEDGMENTS The authors thank the Nebraska State Penitentiary and the Nebraska Crime Commission for their support in accomplishing this project.

DISCLOSURES The authors report no conflict of interest related to the study detailed within this article nor do the authors have additional income to declare.

FUNDING There was no funding for this study.

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