Inhibitory Control in People Who Self-Injure Evidence For

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Psychiatry Research

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Inhibitory control in people who self-injure: Evidence for impairment and enhancement

Kenneth J.D. Allen n, Jill M. Hooley

Department of Psychology, Harvard University, 33 Kirkland Street, Cambridge, MA 02138, USA article info abstract

Article history: Self-injury is often motivated by the desire to reduce the intensity of negative affect. This suggests that Received 14 March 2014 people who self-injure may have difﬁculty suppressing negative emotions. We sought to determine Received in revised form whether self-injuring individuals exhibit impaired inhibitory control over behavioral expressions of 6 August 2014 negative emotions, when responding to images containing aversive emotional content. Self-injuring Accepted 9 November 2014 participants and healthy controls completed a Stop Signal Task in which they were asked to judge the valence (positive or negative) of images. Three types of images depicted emotional content (neutral/ Keywords: positive/negative). A fourth type depicted self-cutting. An unpredictable “stop signal” occurred on some Non-suicidal self-injury trials, indicating that participants should inhibit their responses to images presented on those trials. Self-harm Compared to controls, self-injuring participants showed poorer inhibition to images depicting negative Impulsivity emotional content. Additionally, they showed enhanced inhibition to self-injury images. In fact, self- Emotion regulation Executive functioning injuring participants showed comparable response inhibition to cutting images and positive images, Response inhibition whereas controls showed worse inhibition to cutting images compared to all other types of images. Stop Signal Task Consistent with the emotion regulation hypothesis of self-injury, people who self-injure showed impaired negative emotional response inhibition. Self-injuring individuals also demonstrated superior control over responses to stimuli related to self-injury, which may have important clinical implications. & 2014 Elsevier Ireland Ltd. All rights reserved.

1. Introduction types of negative emotions (Nock and Prinstein, 2004; Jacobson and Gould, 2007; Nock, 2009). Aversive affective states (e.g., anger, Non-suicidal self-injury (NSSI) refers to deliberate self-harm anxiety, and sadness) are frequently reported antecedents to NSSI without the intent to die. In a recent cross-national study, almost a (Nock et al., 2009), and people who engage in self-injury often quarter of adolescents reported having engaged in NSSI within the experience decreases in negative emotional and psychophysiolo- last year (Giletta et al., 2012). Although these acts themselves are gical arousal after exposure to NSSI proxies in the laboratory “non-suicidal”, NSSI is strongly associated with suicidality. In one (Haines et al., 1995; Welch et al., 2008; Franklin et al., 2010). The large randomized controlled trial for treatment-resistant depres- emotion regulation model thus suggests that an impaired ability to sion, compared to baseline suicide attempts, NSSI was a better self-modulate or inhibit unpleasant emotions is a central feature of predictor of future suicide attempts (Asarnow et al., 2011). The NSSI. That is, according to this model, people who self-injure may prevalence and prognostic implications of NSSI have contributed possess deﬁcits in inhibitory control over negative affect. In the to its inclusion in the latest edition of the Diagnostic and Statistical current study we examined this possibility in a laboratory setting. Manual of Mental Disorders (5th ed., American Psychiatric Relatively few studies to date have examined neuropsycholo- Association, 2013) as a condition warranting further research. gical functioning in NSSI. Some researchers have found no differ- Together, self-injurious behaviors are among the leading causes ences between individuals who harm themselves and controls on of injury and death worldwide (Nock et al., 2008). various measures of executive functioning (Ohmann et al., 2008) Although people report a variety of motivations for engaging in or on measures of behavioral impulsivity (Janis and Nock, 2009). NSSI, one functional model of self-injurious behaviors that has However, there is some evidence that currently self-injuring received considerable empirical attention suggests that they serve individuals (i.e., those who had done so in the past 30 days) make to regulate affect by providing escape or distraction from certain more impulsive decisions on the Iowa Gambling Task than formerly self-injuring individuals (Oldershaw et al., 2009). Despite its conceptual relevance to impulsivity, inhibition – one of the core n – Corresponding author. Tel.: þ1 219 669 4491; fax: þ1 617 495 3728. executive functions (Miyake and Friedman, 2012) has not been E-mail address: [email protected] (K.J.D. Allen). well studied in this population. http://dx.doi.org/10.1016/j.psychres.2014.11.033 0165-1781/& 2014 Elsevier Ireland Ltd. All rights reserved.

Inhibitory control (or response inhibition) refers to the ability to The main goal of this study was to empirically test predictions halt the execution of an already initiated action (Nigg, 2000). People made by the emotion regulation model of self-injury, as well as to who report high levels of trait impulsivity exhibit poor inhibitory reconcile the divergent state of the literature regarding self-report control, suggesting that problems controlling behavior might reflect and behavioral measures of impulsivity among people who self-injure. difficulty in “stopping” processes rather than overactive approach Specifically, we hypothesized that self-injuring participants would tendencies (Logan et al., 1997). Deficient inhibitory control is show poorer inhibitory control over their behavioral responses to neg- characteristic of several psychiatric disorders that involve impulsive ativeaffectivestimuli.Additionally,wepredictedthattheywould behavior, including attention deficit hyperactivity disorder (ADHD; show poorer inhibitory control over their responses to NSSI stimuli. Lijffijt et al., 2005, but see also Alderson et al., 2007)bulimia Finally, we examined associations between cognitive task performa- nervosa (Wu et al., 2013), and substance use disorders (Rubio et al., nce and self-reported impulsivity, as well as symptoms of anxiety, 2008; de Wit, 2009). Given the relatively high prevalence of self- depression, and BPD. injury in these clinical populations relative to community samples (Nock et al., 2006; Peebles et al., 2011; Hinshaw et al., 2012), it is possible that impaired inhibitory control is associated with a variety 2. Methods of direct and indirect self-injurious behaviors. 2.1. Overview of procedure Only two studies have examined inhibitory control specifically in people who self-injure (Glenn and Klonsky, 2010; Fikke et al., 2011), Participants were recruited from the greater Boston area over approximately employing the Stop Signal Task (SST; Logan et al., 1984) to assess three months. Printed advertisements distributed on local university campuses and behavioral response inhibition. On each trial in this task, participants online postings on the website Craigslist directed interested individuals to an are presented with either a right- or left-facing arrow, and must online survey that collected demographic information and information about self- quickly press the button that corresponds to the direction of the injury. Eligible individuals were invited to a laboratory session. In the laboratory, participants completed several self-report measures and were administered an stimulus. However, on some trials, an auditory tone (or “stop signal”) intelligence test. They then completed a battery of computerized cognitive tasks rapidly follows the arrow, indicating that the prepotent response that included the SST. All participants were provided written informed consent to a must be withheld. Glenn and Klonsky (2010) found no differences in protocol approved by the Harvard University Institutional Review Board. response inhibition between participants who self-injured and those who did not. Fikke et al. (2011) reported that adolescents engaging in 2.2. Participants “low-severity” NSSI were poorer at inhibiting initiated responses compared to those engaging in “high-severity” NSSI, but both groups Participants (N¼67) included 34 healthy controls (22 females; 12 males) and performed comparably to healthy controls. Notably, no previous 33 people who reported self-injury (25 females; 8 males) aged 18–53 (mean age 23; see Table 1). Healthy controls reported no history of mental illness or head research has directly assessed inhibitory control over emotional res- injury on the online survey, indicating specifically that they (a) had never received ponses among people who self-injure, an omission that may partially a diagnosis of or treatment for any Axis I disorder or ADHD; (b) did not use explain mixed findings in this literature. Self-injury is an action that psychiatric medication; and (c) had never experienced a concussion. One female often occurs in response to a negative emotion. Therefore, a domain and two males reported a past suicide attempt but no deliberate destruction of of executive functioning that may be particularly relevant to NSSI is body tissue. These participants were excluded from all analyses. Self-injuring participants were identified via the following item: “Have you motor inhibition to stimuli that evoke unpleasant emotional reac- ever intentionally harmed yourself (e.g., cut or burn)?” Of the 33 participants who tions. Accordingly, we modified the SST to include various affective endorsed this item, 17 (51.5%) reported engaging in self-injury within the past year. images in place of the standard arrow stimuli. Eight participants (24.2%) also reported a past suicide attempt on the Schedule for We used a laboratory-based procedure to examine differences in Nonadaptive and Adaptive Personality (see below) in addition to endorsing intentional self-injury on the item mentioned above. 22 self-injuring participants inhibitory control between participants who self-injured and control participants who did not. We also sought to examine the role of several variables that we believed might contribute to an association between self-injury and inhibitory control. NSSI is often con- Table 1 ceptualized as an impulsive behavior, and it has been suggested that Demographic & clinical characteristics. certain people engage in NSSI because it requires little planning or HC (n¼31) NSSI (n¼33) χ2 or t, p, Cohen's d additional materials (i.e., the Pragmatic Hypothesis, Nock, 2009). Consistent with this idea, people who engage in NSSI often self- Sex n (%) 0.51, 0.48 report higher levels of impulsivity (Janis and Nock, 2009; Glenn and Female 21 (67.74) 25 (75.75) Klonsky, 2010; Di Pierro et al., 2012). Given the link between Male 10 (32.26) 8 (24.24) impulsivity and inhibitory control (Logan et al., 1997), it is plausible Ethnicity n (%) 1.20, 0.88 White 21 (67.74) 23 (69.70) to suggest that higher levels of impulsivity may be related to poorer African-American 3 (9.68) 3 (9.10) emotional inhibition in people who self-injure. Additionally, stimuli Asian 3 (9.68) 5 (15.15) related to self-injury are commonly thought to trigger NSSI urges Latino/a 2 (6.45) 1 (3.03) (Lewis et al., 2011). If NSSI is an impulsive behavior, and if NSSI Biracial/Other 2 (6.45) 1 (3.03) Age, years 23.71 (7.19) 22.45 (4.36) -0.85, 0.40 stimuli trigger this behavioral impulse, we might expect that WAIS Vocabulary 12.48 (3.00) 13.00 (2.89) 0.70, 0.49 NSSI stimuli would also disrupt inhibitory control. Therefore in this BAIa 7.67 (8.93) 12.64 (7.30) 2.43, 0.02, 0.61 study we also assessed the possibility that people who self-injure BDI-II 8.81 (7.42) 18.30 (10.51) 4.15,o0.001, 1.04 would show behavioral disinhibition when confronted with NSSI- SNAP BPDb 8.55 (5.42) 13.94 (5.85) 3.78, 0.001, 0.91 c related stimuli. SNAP Impulsivity 5.55 (3.95) 6.88 (4.44) 1.25, 0.22

Self-injurious behavior is a symptom of borderline personality Note.HC¼healthy control group; NSSI¼self-injury group; BAI¼Beck Anxiety disorder (BPD). However, NSSI is also common in individuals with Index; BDI-II¼Beck Depression Inventory-II; SNAP Impulsivity¼Schedule for Non- anxiety and mood disorders (Nock et al., 2006). Evidence suggests adaptive and Adaptive Personality Scale Impulsivity Subscale; and SNAP that deﬁcits in inhibitory control over negative emotional processing BPD¼Schedule for Nonadaptive and Adaptive Personality Scale Borderline Person- ality Disorder Subscale. Values are given as mean (standard deviation) unless are characteristic of each of these disorders (e.g., Korﬁne and Hooley, otherwise indicated. 2000; Joormann and Gotlib, 2010; Hopkins et al., 2013). Thus, we a n¼30 healthy controls, n¼33 self-injuring participants; additionally sought to clarify the role of these factors in negative b n¼29 healthy controls, 31 self-injuring participants; and emotional response inhibition among self-injuring individuals. c n¼29 healthy controls, 33 self-injuring participants.

(66.7%) indicated having at least one lifetime psychiatric diagnosis, and among trial led to an increase in the SSD on the next stop trial, with each successive stop these, 15 reported two or more disorders (45.5% of the self-injuring group). trial increasing in difficulty until inhibition failed (at which point the SSD was Depression was the most commonly self-reported diagnosis (19 participants; subsequently reduced). 57.6%), followed by generalized anxiety disorder (11 participants; 33.3%), eating SSRT (the amount of time an individual needed to inhibit responses) was disorders (six participants; 18.2%), and bipolar disorder (three participants; 9.1%). calculated by subtracting the median stop signal delay time from the mean go- Two participants (6.1%) reported having obsessive-compulsive disorder and two signal reaction time (GSRT). Longer latencies indicate poorer inhibitory control. participants reported panic disorder. Finally, one participant reported ADHD and Although the total number of commission errors was fixed at approximately 50%, another participant reported a disorder in the autism spectrum1 (3.0% each). participants were presented with roughly equal numbers of stimuli from each of 15 participants (45.5%) reported use of psychiatric medication. the categories described below, allowing us to use the proportion of commission errors relative to the total number of stop trials in each stimulus category as the primary dependent variables. These percentages represent participants' success 2.3. Measures rates when prompted to inhibit responses to different kinds of stimuli. Consistent with the aims of this study, we modified an auditory SST to assess 2.3.1. Beck Anxiety Inventory (BAI) inhibitory control over affective judgments. To this end, we used images from the – The BAI (Beck et al., 1988) is a widely used 21-item Likert-type (0 3) self-report International Affective Picture System (IAPS; Lang et al., 2008), matched for content measure that assesses the presence and severity of anxiety symptoms in the past intensity, as stimuli in both target (“go”) and inhibition (“stop”) trials. The affective ¼ week. This questionnaire has high internal consistency (Cronbach's alpha 0.90 in stimuli were comprised of three types of images: neutral, positive, and negative. the present sample) and test-retest reliability, as well as good convergent and There were 12 images of each type, resulting in 48 emotional images overall. We discriminant validity (Beck et al., 1988). also developed a fourth (self-injury) stimulus category. This involved 12 images depicting various (before and after) stages of self-injury. Six photographs taken in 2.3.2. Beck Depression Inventory-II (BDI-II) our laboratory showed sharp objects (e.g., knife, razor, scissors, etc.) pressed against The BDI-II (Beck et al., 1996a) is a 21-item Likert-type (0–3) self-report measure a bare wrist. We combined these with six additional photographs (taken from of depressive symptoms experienced in the past week. Its psychometric properties online websites) that depicted bloodied and lacerated arms indicative of recent are well established in psychiatric and community samples (Beck et al., 1996b; self-cutting. Study participants were instructed to report the valence of each image Steer and Clark, 1997). In this study, Cronbach's alpha for the BDI-II was 0.91. (pleasant or unpleasant) as quickly and as accurately as possible using a keyboard marked with a smiling face and a frowning face. During stop trials, images were followed by an auditory tone indicating that the affective response should be 2.3.3. Schedule for Nonadaptive & Adaptive Personality-2 (SNAP) inhibited. Crucially, we expected the rate of commission errors (i.e., the number Impulsivity and borderline traits were assessed using the second edition of the of failed stop trials relative to the total number of stop trials for each image type) SNAP (Calabrese et al., 2012; Clark et al., in press), a 390-item true/false self-report to vary across stimulus categories, indicating that responses to certain kinds of questionnaire designed to measure traits associated with personality disorders. images are more difficult to inhibit than others. Other variables of interest included ‘ This inventory includes items corresponding to 15 personality traits ( trait and the GSRT, the SSRT (i.e., the difference between the GSRT and the SSD), and ’ ‘ ’ temperament scales ) and 13 personality disorders ( diagnostic scales ) based on omission errors. DSM-IV criteria. This instrument effectively differentiates Axis-II disorders from other forms of psychopathology and also discriminates among specific personality disorders based on the diagnostic scales and composites of the trait and tempera- 2.4. Statistical procedures ment scales (Morey et al., 2003). The SNAP impulsivity scale is comprised of 19 items that indicate disinhibited, Independent t-tests were first conducted to compare groups on demographic reckless, and impulsive behavior. The SNAP BPD scale consists of 28 items that variables and general task measures (GSRT, SSRT, and both types of errors). We assess various facets of BPD, such as aggression, impulsivity, emotional lability, and then conducted a 2 3 within-subjects analysis of variance (ANOVA) to examine self-injury. The scales of the SNAP show incremental validity in predicting the effects of group (self-injury vs. healthy controls) and image valence (neutral, symptoms and personality dimensions associated with BPD (Clark et al., 1993; positive, negative) on the proportion of commission errors committed, a measure Reynolds and Clark, 2001; Stepp et al., 2005). Overall, the SNAP has acceptable of inhibitory control. A significant group by image valence interaction was internal consistency and temporal stability (Calabrese et al., 2012). Additionally, followed up with independent samples t-tests to compare self-injuring partici- personality disorder composites based on SNAP trait and temperament scales pants to healthy controls in each stimulus category. An additional t-test compared demonstrate good convergent and discriminant validity (Melley et al., 2002; Morey self-injuring participants to healthy controls in their inhibitory control over et al., 2003). In this sample, the internal reliabilities of the SNAP Impulsivity and responses to images depicting self-injury. We also ran correlations between BPD scales were 0.82 and 0.85, respectively. dependent variables on which group differences emerged and constructs derived from self-report: anxiety, depression, impulsivity, and BPD symptoms. All 2.3.4. Wechsler Adult Intelligence Scale-IV (WAIS) Vocabulary subtest analyses were conducted using SPSS/PASW 21.0 (SPSS, Chicago, IL). One male The Vocabulary subtest of the WAIS (Wechsler, 2008) was administered to control participant had incomplete BAI data, and four participants had incom- assess cognitive ability. Of the WAIS subtests, it is the single best indicator of plete SNAP data: one female control on both the impulsivity and BPD scales, general intelligence (Groth-Marnat, 2009) and is commonly used for this purpose another female control on only the BPD scale, a male control on the impulsivity (Lezak et al., 2004). Substantial evidence supports the psychometric properties of scale, and a female self-injuring participant on the BPD scale. These participants the WAIS (Wechsler, 2008). were excluded from all analyses involving scales on which they had incomplete data.

2.3.5. Stop-Signal Task (SST) The SST is a paradigm used to probe individual differences in inhibitory control over behavioral responses (Verbruggen and Logan, 2008). In the standard version 3. Results of this task, participants are instructed to discriminate between serially displayed “ ” left and right arrows as quickly and accurately as possible by pressing the key that Demographic and self-reported clinical variables are presented corresponds to the direction of the arrow. However, unpredictable stop signals appear almost immediately following some stimuli, indicating to the participant in Table 1. There were no differences between groups in terms of 2 that their response should be withheld. These stop signals occur with a variable age (t(62)¼0.85, p¼0.40), gender (χ (1, N¼64)¼0.51, p¼0.48), delay after the presented arrow (i.e., the target), and when the delay is sufﬁciently or intelligence (t(62)¼0.70, p¼0.49), as measured by the WAIS short, participants will successfully terminate initiated responses. In contrast, Vocabulary subtest. Self-injuring participants reported more symp- inhibition is more likely to fail as the latency between the arrow presentation ¼ ¼ ¼ and the stop signal increases. Individuals differ in their inhibitory control over pre- toms of anxiety (t(61) 2.43, p 0.02, Cohen's d 0.61), depression potent responses, and thus, the stop signal delay (SSD) is adjusted on each trial to (t(62)¼4.15, po0.001, Cohen's d¼1.04), and BPD (t(59)¼3.62, reveal the amount of time necessary for successful motor inhibition in each p¼0.001, Cohen's d¼0.92), but not higher levels of impulsivity participant, known as stop-signal reaction time (SSRT; Logan and Cowan, 1984). (t(60)¼1.08, p¼0.29), compared to healthy controls. Following conventionally accepted procedures, the SSD was adjusted following each stop trial to ensure that roughly half of stop signals resulted in commission errors (Osman et al., 1986, 1990). That is, successful response inhibition on one stop 3.1. Overall task performance

The SST data are presented in Table 2. When all four stimulus 1 Given the theoretical significance of response inhibition to ADHD, as well as categories were considered there were no group differences in potential for social and emotional deficits associated with autism spectrum ¼ problems, we conducted all analyses with and without each of these participants' overall task performance, as indicated by GSRT (t(62) 0.08, data; no significant results were changed. p¼0.94), SSRT (t(58.46)¼0.89, p¼0.38), and errors of omission

(t(62)¼0.00, p¼0.99) or commission (t(62)¼0.83, p¼0.41). That is, depicted neutral, positive, or negative emotional content. In general, self-injuring participants and healthy controls were equivalent in both groups showed poorer suppression of responses to positive and their mean reaction time to target stimuli overall as well as in the negative images compared to neutral images (see Fig. 1). Also as amount of time required to inhibit their responses on stop trials. predicted, the ANOVA revealed an interaction between group and Additionally, participants in both groups made a comparable number image valence, F(1.83, 113.73)¼4.12, p¼0.02, partial η2¼0.06, indicating of errors throughout the task as a whole. that the pattern of successful inhibition across the three types of IAPS images differed between self-injuring participants and healthy controls. Follow-up t-tests revealed that, compared to healthy controls 3.2. IAPS images (mean¼46.36%; S.D.¼16.43%), self-injuring participants committed a greaternumberoferrorstoimageswithnegativeaffectivecontent A 2 (group) 3 (image valence) repeated-measures ANOVA (mean¼57.25%, S.D.¼16.91%; t(62)¼2.61, p¼0.01, Cohen's d¼0.73; see (adjusted to correct for a violated sphericity assumption) revealed a Fig. 1). There were no group differences between self-injuring partici- main effect of group, such that self-injuring participants made more pants and controls in terms of their ability to inhibit responses to commission errors overall to the IAPS images (F(1, 62)¼5.17, p¼0.03, neutral (mean¼30.69%, S.D.¼14.01% and mean ¼36.64%, S.D.¼16.34%, partial η2¼0.08). As expected, there was also a main effect of image respectively; t(62)¼1.57, p¼0.12) or positive (mean¼50.27%, valence, F(1.83, 113.73)¼18.95, po0.001, partial η2¼0.23, indicating S.D.¼16.25% and mean ¼43.66%, S.D.¼13.47%, respectively; t(62)¼ that inhibitory control varied according to whether the presented image 1.77, p¼0.08) images.

Table 2 SST variables. 3.3. NSSI images

HC (n¼31) NSSI (n¼33) t, p An additional independent samples t-test was conducted to GSRT 785.73 (112.65) 787.63 (89.93) 0.08, 0.94 determine whether people who self-injure committed inhibition SSRT 345.39 (55.96) 360.26 (76.84) 0.89, 0.38 errors at a greater rate than healthy controls to images depicting Omission errors 2.48 (3.53) 2.48 (3.51) 0.00, 0.99 NSSI. Contrary to prediction, self-injuring participants committed Commission errors 22.10 (2.24) 22.55 (2.08) 0.83, 0.41 signiﬁcantly fewer errors to NSSI images (mean¼48.43%, S.D.¼ Note. SST¼Stop-Signal Task; GSRT¼Go-signal reaction time; and SSRT¼Stop- 16.95%) compared to healthy controls (mean¼59.65%, S.D.¼ signal reaction time. Values are given as mean (standard deviation). 19.82%; t(62)¼2.44, p¼0.02, Cohen's d¼0.59; see Fig. 2).

Self-Injurers Healthy Controls 70 70 Self-Injurers Healthy Controls ** *

60 60

50 50

Percentage of Errors on Stop Signal Trials 20 Percentage of Errors on Stop Signal Trials 20

0 Neutral Positive Negative IAPS Image Type 0 NSSI Images Fig. 1. Percentage of commission errors on stop trials by IAPS image type. Note.**po0.01; IAPS¼International Affective Picture System. Error bars represen- Fig. 2. Percentage of commission errors on stop trials to NSSI images. t7one standard error of the mean. Note.*po0.05. Error bars represent7one standard error of the mean.

Table 3 to emotional images, specifically to those depicting negative Clinical correlates of inhibitory control. emotional content. It is possible that people who experience greater difficulty suppressing unwanted emotions rely on beha- Clinical measure Neg. Commission NSSI Commission image errors image errors viors that provide immediate and powerful reinforcement (such as cutting or substance abuse) to avoid or reduce the intensity of BAI 0.18 0.17 0.13 0.30 these emotions. Unsurprisingly, all participants demonstrated BDI-II 0.17 0.17 0.16 0.20 more difficulty inhibiting affective judgments to images contain- SNAP BPD 0.23 0.07 0.17 0.19 ing valenced (as opposed to neutral) emotional content, but this SNAP impulsivity 0.24 0.06 0.06 0.66 Self-injuring days in the 0.29 0.11 difference was more marked among the participants who self- past yeara injured. In line with other studies of behavioral impulsivity in people who self-injure (e.g., Janis and Nock, 2009; Fikke et al., ¼ ¼ Note. BAI Beck Anxiety Index; BDI-II Beck Depression Inventory-II; SNAP Impul- 2011), there was no broad deficit in inhibitory control as indicated sivity¼Schedule for Nonadaptive and Adaptive Personality Scale Impulsivity Subscale; and SNAP BPD¼Schedule for Nonadaptive and Adaptive Personality by SSRT or total commission errors. Scale Borderline Personality Disorder Subscale. All p values are derived from two- Contrary to our secondary hypothesis, self-injuring participants tailed tests. found behavioral responses to NSSI images easier to inhibit than a Analysis conducted in self-injuring (n¼33) participants only. did healthy individuals. In fact, the control group committed a greater proportion of commission errors to these types of images than to any of the other stimuli. Conversely, self-injuring partici- 3.4. Clinical correlates of task performance pants showed better inhibitory control over responses to NSSI images than to negative emotional images, and their error rate to Do elevated scores on clinical constructs explain self-injuring these stimuli was comparable to their error rates for positive participants' performance on the SST? Although they scored higher emotional images. Put simply, self-injuring participants responded on measures of anxiety, depression, and BPD symptoms, none of similarly when presented with positive emotional images or these variables were significantly associated with either commission images of cutting. This raises the possibility that they may not errors to the negative emotional images or the NSSI images; however, view NSSI images as aversive. Perhaps through conditioning, there was a trend-level relationship between symptoms of BPD and people who engage in self-injury may learn to associate stimuli impaired negative emotional response inhibition, r(61)¼0.23, p¼0.07 related to self-injury with relief, and possibly even with reward (cf. (see Table 3). As mentioned earlier, self-injuring participants did not Franklin et al., 2014). An alternative, but not mutually exclusive report higher levels of impulsivity. Nonetheless, given its theoretical explanation is that by engaging in NSSI, individuals who self- relevance to inhibitory control, we evaluated the relationship bet- injure habituate to the sight of blood and cutting. However, if this ween scores on the SNAP Impulsivity scale and task performance. were indeed the case, we might expect the error rate when Similar to the BPD scale, there was a non-significant trend association viewing NSSI images to be more similar to the error rate for between self-reported impulsivity and poor negative emotional res- neutral images. The negative association between frequency of ponse inhibition, r(62)¼0.24, p¼0.06. recent self-injury and the commission error rate to NSSI images In light of these findings, we conducted one additional analysis. supports either of these possibilities. To confirm that it was NSSI rather than BPD symptoms or impulsivity This study has a number of limitations. One of the fundamental that was accounting for poorer negative emotional response inhibi- assumptions of this research is that NSSI is primarily motivated by the tion, we entered all three variables simultaneously into a regression desire to relieve aversive emotions. Whereas there is a substantial model. Of the three variables, using forward selection, NSSI was the literature to support this view, other motivations such as self-criticism only one to enter the model and account for significant variance, are also important (see Hooley et al., 2010; Hooley and St. Germain, F(3, 59)¼3.59, p¼0.02, R2¼0.16. 2014). Moreover, nuanced methods such as ecological momentary assessment (EMA) suggest that although negative affective states 3.5. Self-injury and task performance oftendoprecedeNSSI,theymaynotdosoimmediately,anddepen- dingonthetypeofnegativeaffect(e.g.,guiltorshame),theymay Given our unexpected finding that self-injurers exhibited super- persist for some time following an episode (Armey et al., 2011). ior control over responses to NSSI images, we explored the possi- Additionally, other EMA data indicate that decreased emotional dis- bility that this might be related to their greater familiarity with tress following NSSI may result from increased positive affect, rather stimuli relevant to self-injury. Consistent with this, within the self- than decreased negative affect (Muehlenkamp et al., 2009). injuring group there was a negative association between self-injury Although we conclude that self-injuring participants and con- frequency in the past year and fewer commission errors to NSSI trols perform similarly on the task overall, its design prevents us images (r(33)¼0.29, p¼0.11). Although the correlation was not from examining stop-signal reaction time (SSRT, the most com- significant, the effect size is suggestive of the possibility that self- monly used metric of inhibitory control) in the IAPS images injurers may find NSSI images less aversive, and therefore less separately from the NSSI images. If, as we would expect, the SSRT disruptive of inhibitory control, due to habituation, or perhaps the follows the same pattern as the commission errors, the NSSI group history of positive reinforcement associated with self-injury. This might show general impairment on the task if they were pre- may account for the observed group difference (controls obviously sented only with IAPS emotional images. have no frequency of self-injury) in the commission error rate. It is also the case that many of our self-injuring participants reported other psychological difficulties and diagnoses. Our sample size was not sufficient to assess the individual contributions of each 4. Discussion of these to overall performance on the SST. However, correlational analyses revealed that SST performance was not accounted for by The emotion regulation model of NSSI implicates a deficit in the symptoms of anxiety, depression, or BPD. There was also no evidence ability among people who self-injure to control their mood, and in that high rates of ADHD in our sample could explain our findings. particular, to inhibit unpleasant emotional reactions. Consistent Moreover, although there were trend-level associations between with this idea, people who self-injure showed poorer inhibitory impulsivity/BPD symptoms and negative emotional response inhibi- control than healthy individuals over rapid behavioral responses tion, regression analysis revealed that this was due to their overlap

Please cite this article as: Allen, K.J.D., Hooley, J.M., Inhibitory control in people who self-injure: Evidence for impairment and enhancement. Psychiatry Research (2014), http://dx.doi.org/10.1016/j.psychres.2014.11.033i 6 K.J.D. Allen, J.M. Hooley / Psychiatry Research ∎ (∎∎∎∎) ∎∎∎–∎∎∎ with NSSI rather than because they made independent contributions onset or course of self-injury, as well as whether long-term and explained unique variance. Of course, other (unmeasured) remission is associated with a normalized ability to inhibit auto- clinical variables could also be playing a role. Future studies should matic responses to NSSI-related stimuli. examine a broader range of clinical constructs to further explore this possibility. The self-injury group was identified on the basis of a single- Acknowledgment item measure, and was therefore heterogeneous in terms of recency, frequency, and severity of self-injury. Relatedly, eight of This research was supported by a Karen Stone Fellowship from the the individuals in this group reported a past suicide attempt, so Smart Family Foundation awarded to Kenneth J.D. Allen. The authors some or all of their reported self-injury may not qualify strictly as have no financial disclosures to report. We also thank Lauren Fields, non-suicidal self-injury. However, the two primary findings (defi- Stephanie Klinkenberg, Huong-Duong Phan, and Diheng Zhang for cient negative emotional inhibition and superior inhibition over their assistance with data collection. responses to NSSI images among people who self-injure) remained significant, with roughly comparable effect sizes, even after excl- References uding these individuals. Although self-injuring individuals show similar behavioral inhi- Alderson, R.M., Rapport, M.D., Kofler, M.J., 2007. Attention-deficit/hyperactivity bition to positive and NSSI images, in no case did any participant disorder and behavioral inhibition: a meta-analytic review of the stop-signal classify an NSSI image as positive. Future studies should further paradigm. Journal of Abnormal Child Psychology 35, 745–758. explore how people who engage in NSSI evaluate stimuli related to Allen, K.J.D., Gabbay, F.H., 2013. The amphetamine response moderates the relationship between negative emotionality and alcohol use. Alcoholism: self-injury, using both explicit and implicit measures. The relatively Clinical and Experimental Research 37, 348–360. small sample size in this study encourages replication in larger and American Psychiatric Association, 2013. Diagnostic and Statistical Manual of Mental more diverse populations. Finally, all the NSSI images used in this Disorders, 5th edition APA, Washington, DC. Armey, M.F., Crowther, J.H., Miller, I.W., 2011. Changes in ecological momentary study depicted self-cutting, so it is possible that these results are assessment reported affect associated with episodes of nonsuicidal self-injury. less valid for individuals who engage in other forms of NSSI. Behavior Therapy 42, 579–588. However, the online survey specifically mentioned cutting as an Asarnow, J.R., Porta, G., Spirito, A., Emslie, G., Clarke, G., Wagner, K.D., Vitiello, B., example of deliberate self-injury, and self-cutting is the most Keller, M., Birmaher, B., McCracken, J., Mayes, T., Berk, M., Brent, D.A., 2011. Suicide attempts and nonsuicidal self-injury in the treatment of resistant popular form of NSSI (Sornberger et al., 2012). depression in adolescents: findings from the TORDIA study. Journal of the These limitations notwithstanding, our results have important American Academy of Child and Adolescent Psychiatry 50, 772–781. clinical implications. Impaired control over negative emotional Beck, A.T., Epstein, N., Brown, G., Steer, R.A., 1988. An inventory for measuring clinical anxiety: psychometric properties. Journal of Consulting and Clinical reactions may be a trans-diagnostic vulnerability factor for risky, Psychology 56, 893–897. reinforcing behaviors. This is consistent with previous research Beck, A.T., Steer, R.A., Ball, R., Ranieri, W., 1996a. Comparison of Beck Depression that suggests that a high level of negative emotionality may InventoriesIA and -II in psychiatric outpatients. Journal of Personality Assess- ment 67, 588–597. promote reward seeking. For example, among people inclined to Beck, A.T., Steer, R.A., Brown, G.K., 1996b. Manual for the Beck Depression pursue a certain kind of reward (i.e., those sensitive to drug Inventory-II. Psychological Corporation, San Antonio, TX. reinforcement), negative emotionality is associated with high-risk, Calabrese, W.R., Rudick, M.M., Simms, L.J., Clark, L.A., 2012. Development and validation of Big Four personality scales for the Schedule for Nonadaptive and high-reward behavior (i.e., binge drinking; Allen & Gabbay, 2013). Adaptive Personality—Second Edition (SNAP-2). Psychological Assessment This study extends that work by showing that self-injury – another 24, 751–763. risky yet reinforcing activity – is associated with deficient inhibi- Clark, L.A., Simms, L.J., Wu, K.D., Casillas, A., in press. Manual for the Schedule for Nonadaptive and Adaptive Personality (SNAP-2). University of Minnesota Press, tion over negative emotional impulses. Future research should Minneapolis, MN. investigate whether a common neurocognitive factor underlies Clark, L.A., McEwen, J.L., Collard, L.M., Hickok, L.G., 1993. Symptoms and traits of various risk behaviors that are used to regulate emotions. personality disorder: two new methods for their assessment. Psychological – Given self-injuring individuals' comparable inhibition error Assessment 5, 81 91. de Wit, H., 2009. Impulsivity as a determinant and consequence of drug use: a rates to images containing positive emotional content and those review of underlying processes. Addiction Biology 14, 22–31. depicting NSSI, this study also adds to accumulating evidence that Di Pierro, R., Sarno, I., Perego, S., Gallucci, M., Madeddu, F., 2012. Adolescent stimuli related to self-injury may not elicit negative emotional nonsuicidal self-injury: the effects of personality traits, family relationships and maltreatment on the presence and severity of behaviors. European Child and arousal in people who engage in NSSI (Franklin et al., 2014). If this Adolescent Psychiatry 21, 511–520. effect can be replicated, this is of great clinical concern. Healthy Fikke, L.T., Melinder, A., Landrø, N.I., 2011. Executive functions are impaired in individuals show a natural aversion to NSSI stimuli – an aversion adolescents engaging in non-suicidal self-injury. Psychological Medicine 41, 601–610. that is apparently lost in people who deliberately harm them- Franklin, J.C., Hessel, E.T., Aaron, R.V., Arthur, M.S., Heilbron, N., Prinstein, M.J., 2010. selves. If people who self-injure associate self-injury with reward, The functions of nonsuicidal self-injury: support for cognitive-affective regula- in addition to the emphasis on negative reinforcement in the tion and opponent processes from a novel psychophysiological paradigm. Journal of Abnormal Psychology 119, 850–862. emotion regulation model, researchers should elucidate how Franklin, J.C., Lee, K.M., Puzia, M.E., Prinstein, M.J., 2014. Recent and frequent positive reinforcement processes contribute to the etiology and nonsuicidal self-injury is associated with diminished implicit and explicit maintenance of NSSI. For clinicians, re-instating this natural aversion toward self-cutting stimuli. Clinical Psychological Science 2, 306–318. Giletta, M., Scholte, R.H., Engels, R.C., Ciairano, S., Prinstein, M.J., 2012. Adolescent aversion may represent a mechanism of change in the treatment non-suicidal self-injury: a cross-national study of community samples from of self-injury. Italy, the Netherlands and the United States. Psychiatry Research 197, 66–72. Consistent with the emotion regulation hypothesis, people who Glenn, C.R., Klonsky, E.D., 2010. Prospective prediction of nonsuicidal self-injury: a – self-injure show deficits in inhibitory control over behavioral res- 1-year longitudinal study in young adults. Behavior Therapy 42, 751 762. Groth-Marnat, G., 2009. Handbook of Psychological Assessment, 5th edition Wiley ponses to unpleasant emotional stimuli. This study also finds & Sons, Hoboken, NJ. evidence that contrasts with the notion that self-injuring indivi- Haines, J., Williams, C.L., Brain, K.L., Wilson, G.V., 1995. The psychophysiology of – duals are generally impulsive, and in particular, that NSSI-related self-mutilation. Journal of Abnormal Psychology 104, 471 489. Hinshaw, S.P., Owens, E.B., Zalecki, C., Huggins, S.P., Montenegro-Nevado, A.J., stimuli elicit behavioral disinhibition. This research contributes to Schrodek, E., Swanson, E.N., 2012. Prospective follow-up of girls with atten- a growing body of literature suggesting that self-injury may be tion-deficit/hyperactivity disorder into early adulthood: continuing impair- associated with rather circumscribed cognitive deficits. These ment includes elevated risk for suicide attempts and self-injury. Journal of – fi Consulting and Clinical Psychology 80, 1041 1051. ndings encourage future work that explores whether impaired Hooley, J.M., Ho, D.T., Slater, J., Lockshin, A., 2010. Pain perception and nonsuicidal inhibitory control over negative emotional reactions predicts the self-injury: a laboratory investigation. Personality Disorders 1, 170–179.

Hooley, J.M., St. Germain, S.A., 2014. Nonsuicidal self-injury, pain, and self-criticism: Nock, M.K., Borges, G., Bromet, E.J., Cha, C.B., Kessler, R.C., Lee, S., 2008. Suicide and does changing self-worth change pain endurance in people who engage in self- suicidal behavior. Empidemiological Reviews 30, 133–154. injury? Clinical Psychological Science 2, 297–305. Nock, M.K., Joiner Jr., T.E., Gordon, K.H., Lloyd-Richardson, E., Prinstein, M.J., 2006. Hopkins, J., Lavigne, J.V., Gouze, K.R., Lebailly, S.A., Bryant, F.B., 2013. Multi-domain Non-suicidal self-injury among adolescents: diagnostic correlates and relation models of risk factors for depression and anxiety symptoms in preschoolers: to suicide attempts. Psychiatry Research 144, 65–72. evidence for common and specific factors. Journal of Abnormal Child Psychol- Nock, M.K., Prinstein, M.J., 2004. A functional approach to the assessment of self- – ogy 41, 705 722. mutilative behavior. Journal of Consulting and Clinical Psychology 72, 885–890. Jacobson, C.M., Gould, M., 2007. The epidemiology and phenomenology of non- Nock, M.K., Prinstein, M.J., Sterba, S.K., 2009. Revealing the form and function of self- suicidal self-injurious behavior among adolescents: a critical review of the injurious thoughts and behaviors: a real-time ecological assessment study among – literature. Archives of Suicide Research 11, 129 147. adolescents and young adults. Journal of Abnormal Psychology 118, 816–827. Janis, I.B., Nock, M.K., 2009. Are self-injurers impulsive? Results from two Ohmann, S., Schuch, B., Konig, M., Blaas, S., Fliri, C., Popow, C., 2008. Self-injurious behavioral laboratory studies. Psychiatry Reseach 169, 261–267. behavior in adolecent girls. Psychopathology 41, 226–235. Joormann, J., Gotlib, I.H., 2010. Emotion regulation in depression: relation to Oldershaw, A., Grima, E., Jollant, F., Richards, C., Simic, M., Taylor, L., Schmidt, U., cognitive inhibition. Cognition and Emotion 24, 281–298. 2009. Decision making and problem solving in adolescents who deliberately Korfine, L., Hooley, J.M., 2000. Directed forgetting of emotional stimuli in borderline self-harm. Behavioral Medicine 39, 95–104. personality disorder. Journal of Abnormal Psychology 109, 214–221. Osman, A., Kornblum, S., Meyer, D.E., 1986. The point of no return in choice reaction Lang, P.J., Bradley, M.M., Cuthbert, B.N., 2008. International Affective Picture System (IAPS): Affective Ratings of Pictures and Instruction Manual, Technical Report time: controlled and ballistic stages of response preparation. Journal of – A-8. University of Florida, Gainesville, FL. Experimental Psychology: Human Perception and Performance 12, 245 258. Lewis, S.P., Health, N.L., St. Denis, J.M., Noble, R., 2011. The scope of non-suicidal Osman, A., Kornblum, S., Meyer, D.E., 1990. Does motor programming necessitate self-injury on YouTube. Pediatrics 127, 2010–2317. response execution? Journal of Experimental Psychology: Human Perception Lezak, M.D., Howieson, D.B., Loring, D.W., 2004. Neuropsychological Assessment, and Performance 16, 183–198. 4th edition Oxford University Press, New York, NY. Peebles, R., Wilson, J.L., Lock, J.D., 2011. Self-injury in adolescents with eating Lijffijt, M., Kenemans, J.L., Verbaten, M.N., van Engeland, H., 2005. A meta-analytic disorders: correlates and provider bias. Journal of Adolescent Health: Official review of stopping performance in attention-deficit/hyperactivity disorder: defi- Publication of the Society for Adolescent Medicine 48, 310–313. cient inhibitory motor control? Journal of Abnormal Psychology 114, 216–222. Reynolds, S.K., Clark, L.A., 2001. Predicting dimensions of personality disorder from Logan, G.D., Cowan, W.B., 1984. On the ability to inhibit thought and action: domains and facets of the Five-Factor Model. Journal of Personality 69, a theory of an act of control. Psychological Review 91, 295–327. 199–222. Logan, G.D., Cowan, W.B., Davis, K.A., 1984. On the ability to inhibit simple and Rubio, G., Jiménez, M., Rodríguez-Jiménez, R., Martínez, I., Avila, C., Ferre, F., choice reaction time responses: a model and a method. Journal of Experimental Jiménez-Arriero, M.A., Ponce, G., Palomo, T., 2008. The role of behavioral Psychology: Human Perception and Performance 10, 276–291. impulsivity in the development of alcohol dependence: a 4-year follow-up Logan, G.D., Schachar, R.J., Tannock, R., 1997. Impulsivity and inhibitory control. study. Alcoholism: Clinical and Experimental Research 32, 1681–1687. – Psychological Science 8, 60 64. Sornberger, M.J., Heath, N.L., Toste, J.R., McLouth, R., 2012. Nonsuicidal self-injury Melley, A., Oltmanns, T.F., Turkheimer, E., 2002. The schedule for nonadaptive and and gender: patterns of prevalence, methods, and locations among adolescents. adaptive personality (SNAP): temporal stability and predictive validity of the Suicide and Life Threatening Behavior 42, 266–278. – diagnostic scales. Assessment 9, 181 187. Steer, R.A., Clark, D.A., 1997. Psychometric characteristics of the Beck Depression Miyake, A., Friedman, N.P., 2012. The nature and organization of individual Inventory-II with college students. Measurement and Evaluation in Counseling differences in executive functions: four general conclusions. Current Directions and Development 10, 128–136. in Psychological Science 21, 8–14. Stepp, S.D., Trull, T.J., Burr, R.M., Wolfenstein, M., Vieth, A.Z., 2005. Incremental Morey, L.C., Warner, M.B., Shea, M.T., Gunderson, J.G., Sanislow, C.A., Grilo, C., validity of the Structured Interview for the Five-Factor Model of Personality Skodol, A.E., McGlashan, T.H., 2003. The representation of four personality – disorders by the schedule for nonadaptive and adaptive personality dimen- (SIFFM). European Journal of Personality 19, 343 357. sional model of personality. Psychological Assessment 15, 326–332. Verbruggen, F., Logan, G.D., 2008. Response inhibition in the stop-signal paradigm. – Muehlenkamp, J.J., Engel, S.G., Wadeson, A., Crosby, R.D., Wonderlich, S.A., Trends in Cognitive Science 12, 418 424. Simonich, H., Mitchell, J.E., 2009. Emotional states preceding and following Welch, S.S., Linehan, M.M., Sylvers, P., Chittams, J., Rizvi, S.L., 2008. Emotional acts of non-suicidal self-injury in bulimia nervosa patients. Behavior Research responses to self-injury imagery among adults with borderline personality and Therapy 47, 83–87. disorder. Journal of Consulting and Clinical Psychology 76, 45–51. Nigg, J.T., 2000. On inhibition/disinhibition in developmental psychopathology: Wechsler, D., 2008. Wechsler Adult Intelligence Scale-Fourth Edition: Technical and views from cognitive and personality psychology and a working inhibition interpretive manual. Pearson Assessment, San Antonio, TX. taxonomy. Psychological Bulletin 126, 220–246. Wu, M., Hartmann, M., Skunde, M., Herzog, W., Friederich, H.C., 2013. Inhibitory Nock, M.K., 2009. Why do people hurt themselves? New insights into the nature and control in bulimic-type eating disorders: a systematic review and meta- functions of self-injury. Current Directions in Psychological Science 1, 78–83. analysis. PLoS One 31, e83412. http://dx.doi.org/10.1371/journal.pone.0083412.