《社会心理学》课程教学资源（文献资料）Aggression——Reconsidering the Link Between Impulsivity and Suicidal Behavior.pdf

Personality and Social Psychology Review 2014, Vol. 18(4) 366–386 © 2014 by the Society for Personality and Social Psychology, Inc. Reprints and permissions: sagepub.com/journalsPermissions.nav DOI: 10.1177/1088868314535988 pspr.sagepub.com Article Suicide is a global concern, resulting in the annual deaths of approximately one million individuals worldwide (National Institute of Mental Health, 2008). With this in mind, researchers have devoted substantial attention to the identification of risk factors for suicidal behavior. This work has yielded a growing list of variables linked to risk, including hopelessness (e.g., Beck, Steer, Kovacs, & Garrison, 1985), depression (e.g., Bostwick & Pankratz, 2000), non-suicidal self-injury (NSSI; Nock, Joiner, Gordon, Lloyd-Richardson, & Prinstein, 2006), thwarted belonging, and perceived burdensomeness (Joiner, 2005). Although the mechanisms through which these variables are thought to confer risk for suicidal behavior are often delineated and supported by empirical associations, this is not always the case. One variable for which this is noteworthy is impulsivity, which has been reported to be associated with suicidal behavior across a large number of studies (e.g., Dougherty et al., 2004). Impulsivity is a broad construct defined and measured differently across investigations (Lynam & Miller, 2004). Definitions vary in emphasis, with some focusing on the act of engaging in risky behavior (e.g., Barratt, 1993), some focusing on the tendency to opt for smaller immediate rewards over longer term larger rewards (e.g., Bickel & Marsch, 2001), and some emphasizing the importance of specific affective states as influences over an individual’s ability to inhibit sudden drives to engage in problematic behaviors (e.g., Whiteside & Lynam, 2001). Across theories, the construct of impulsivity is typically thought to involve several subcomponents (e.g., negative urgency, deficits in planning), nearly all of which involve a tendency to act without forethought (sensation seeking and lack of perseverance may represent exceptions; e.g., Whiteside & Lynam, 2001). Several theories have been proposed to explain the mechanisms through which impulsivity might be associated with suicidal behavior. Virtually all of these include reference to a distal role for impulsivity but also posit a proximal relationship in which impulsivity explains the nature of the behavior itself. For instance, some researchers posit that the relationship is best thought to represent impulsiveaggression, a tendency to aggress toward others or oneself in response to acute stress (e.g., Mann & Currier, 2009). Consistent with this approach, some have proposed that deficient serotoninergic neurotransmission, represented by low cerebrospinal fluid 5-hydroxyindolacetic acid (CSF-5HIAA) levels, explains the relationship (e.g., Rifai, Reynolds, & Mann, 1992); however, empirical evaluations of this 535988 PSRXXX10.1177/1088868314535988Personality and Social Psychology ReviewAnestis et al. research-article2014 1 University of Southern Mississippi, Hattiesburg, USA 2 Military Suicide Research Consortium, Denver, CO, USA 3 Denver VA Medical Center MIRECC, CO, USA 4 University of Colorado, Boulder, USA 5 Florida State University, Tallahassee, USA Corresponding Author: Michael D. Anestis, Department of Psychology, University of Southern Mississippi, 118 College Drive Box #5025, Hattiesburg, MS 39406, USA. Email: michael.anestis@usm.edu Reconsidering the Link Between Impulsivity and Suicidal Behavior Michael D. Anestis1 , Kelly A. Soberay2,3, Peter M. Gutierrez2,3,4, Theresa D. Hernández4 , and Thomas E. Joiner2,5 Abstract It is widely accepted that suicidal behavior often occurs with little planning. We propose, however, that suicidal behavior is rarely if ever impulsive—that it is too frightening and physically distressing to engage in without forethought—and that suicidal behavior in impulsive individuals is accounted for by painful and fearsome behaviors capable of enhancing their capacity for suicide. We conducted a meta-analysis of the association between trait impulsivity and suicidal behavior and a critical review of research considering the impulsiveness of specific suicide attempts. Meta-analytic results suggest the relationship between trait impulsivity and suicidal behavior is small. Furthermore, studies examining a mediating role of painful and provocative behaviors have uniformly supported our model. Results from our review suggest that researchers have been unable to adequately measure impulsivity of attempts and that measures sensitive to episodic planning must be developed to further our understanding of this phenomenon. Keywords suicide, impulsivity, acquired capability Downloaded from psr.sagepub.com at Remen University of China on September 6, 2015

Anestis et al. 367 alization b the relentless will to remain alive goiner 2010)Should such models prove untrue however the implication would Relatedly,Baumeister (1990)proposed that suicide be that,to override the drive to survive,an individual id an escape I would n to chip away er time.In this e,we ulses to engage in suicidal hehavior while lethal or such a state and.as a result.become increasingly at risk for substantial planning.Although further research testing engaging in such behavior impulsively.Similarly,some mportant components of this model is needed,we argue believet yserves as the diati every etfort to test it thus tar has been supportive posing suicidal behavior is frequently impulsiveis enact lethal self-harm (e.g.,Mann,Waternaux. Haas, problematic. Malone,1999).In this cor ptualization,suicidal behavior i The promin ence of models that describe suicida ewed as un anne est see individuals who display a general tendency to act without impulsive suicidal behavior Conner et a 207:de forethought.Indeed,in explaining the role of impulsivity in Leo,Cerin,Spathonis,Burgis,2005:Mann et al..1996) suicidal ehavior, ann et al.(1)noted that,due to th have typically prope on fee L: picmehdsimcteodhrcTahr ridual or the deg behavior were engaged in impulsively.We argue that the onse to affect in people nature o fthe measures and the designs used in such inves who a ave pre d res ningand impulsive action are not mutually exclusive.sta pretations of published data have resulted in erroneous 582 This ses questions regarding conclusion In addition,we argue that a failure to con ne den ty,as a b e mo ast many common of the construct (e.g sively.The pu se of this review is to consolidate find In this review,the focus is on ings discuss their cations and limitations and vity that the ten cal framew ch of the ribed is the beha notion that people often engage in suicidal behavior with To accomplish these goals.our article is divided into three signif and e In the provide a met state thought is regularly noted as a stater t of fact in liter reviews.For instance. and colle gues (2010)cited a act impu of studie ew,noting th ely ly a cent d tha step beha are unplanned(p.275).Inherent in this viewpoint is the nitude of this assoc iation into belief that suicidal behavior frequently occurs without any a clearer rstanding risk fa sistent defini of im icida behavior and the role of elinicians in identifying and miti- or problematic meas urements of planning,and a pa gating risk (A.R Smith et al..2008) tern of results incompatible with the notion that f an indi eng idal beha with to th cognitive states are canable of ove our alternative con entualization of the association hetwee coming what many would argue is a fundamental impulsivity and suicidal behavior and the empirical evidence component of human nature and an evolutionary imperative underlying that conceptualization

Anestis et al. 367 conceptualization have not been consistently supportive (e.g., Roggenbach, Muller-Oerlinghausen, & Franke, 2002). Relatedly, Baumeister (1990) proposed that suicide attempts represent an escape from aversive self-awareness and that individuals develop a diminished ability to resist impulses to engage in suicidal behavior while experiencing such a state and, as a result, become increasingly at risk for engaging in such behavior impulsively. Similarly, some believe that impulsivity serves as the diathesis in a diathesisstress model in which stressors such as negative life events might interact with impulsivity to result in rash efforts to enact lethal self-harm (e.g., Mann, Waternaux, Haas, & Malone, 1999). In this conceptualization, suicidal behavior is viewed as a frequently unplanned behavioral response to momentary aversive experiences, more likely to occur in individuals who display a general tendency to act without forethought. Indeed, in explaining the role of impulsivity in suicidal behavior, Mann et al. (1999) noted that, due to their propensity toward impulsive action, suicide attempters “feel more suicidal and are more likely to act on feelings” (p. 186). Implicit in such a statement is the notion that suicidal behavior often emerges explosively in response to affect in people who are less capable of inhibiting rash responses to sudden urges. In addition, the same researchers proposed that planning and impulsive action are not mutually exclusive, stating that “the decision to act on a careful plan may be impulsive” (Mann et al., 1996, p. 582). This raises questions regarding the definition of impulsivity, as a decision to act on a plan previously developed in great depth seems to directly contrast many common conceptualizations of the construct (e.g., Whiteside & Lynam, 2001). In this review, the focus is on conceptualizations of impulsivity that emphasize the tendency to act without forethought. A theme across each of the theories just described is the notion that people often engage in suicidal behavior without significant planning and that suicide attempts are often fueled by intense affective states. Indeed, the notion that suicidal behavior frequently occurs with little to no forethought is regularly noted as a statement of fact in literature reviews. For instance, Jeon and colleagues (2010) cited a number of studies detailed later in this review, noting that “with respect to the literature, studies have consistently reported that a considerable proportion of suicidal attempts are unplanned” (p. 275). Inherent in this viewpoint is the belief that suicidal behavior frequently occurs without any detectable progression from low to imminent risk. This supposition has obvious implications with respect to our understanding of risk factors related to imminent suicidal behavior and the role of clinicians in identifying and mitigating risk (A. R. Smith et al., 2008). If an individual can engage in suicidal behavior without prior consideration, this speaks to the notion that momentary affective and/or cognitive states are capable of overcoming what many would argue is a fundamental component of human nature and an evolutionary imperative: the relentless will to remain alive (Joiner, 2010). Should such models prove untrue, however, the implication would be that, to override the drive to survive, an individual would need to chip away at it over time. In this article, we present an alternative model that argues that little, if any, suicidal behavior—lethal or non-lethal—occurs without substantial planning. Although further research testing important components of this model is needed, we argue that every effort to test it thus far has been supportive, whereas evidence that purportedly supports models proposing suicidal behavior is frequently impulsive is problematic. The prominence of models that describe suicidal behavior as frequently impulsive is perhaps best seen through the frequent (and highly cited) efforts to measure impulsive suicidal behavior (e.g., Conner et al., 2007; de Leo, Cerin, Spathonis, & Burgis, 2005; Mann et al., 1996). Such studies have typically approached the association from one of two angles: the trait impulsivity of the individual or the degree to which specific acts of suicidal behavior were engaged in impulsively. We argue that the nature of the measures and the designs used in such investigations have precluded researchers from directly testing models that propose that suicidal behavior is frequently impulsive (see Figure 1a). Furthermore, we believe interpretations of published data have resulted in erroneous conclusions. In addition, we argue that a failure to consider plausible alternative models fully has fueled the belief that suicidal behavior frequently occurs impulsively. The purpose of this review is to consolidate findings, discuss their implications and limitations, and propose a new theoretical framework from which to consider the relationship between impulsivity and suicidal behavior (see Figure 1b). To accomplish these goals, our article is divided into three separate sections. In the first section, we provide a metaanalysis that examines the strength of the relationship between trait impulsivity and suicidal behavior. We anticipate that this relationship will be small in magnitude, thereby highlighting the point that a general tendency to act impulsively is unlikely a central component of suicidal behavior. This analysis represents a critical first step in considering the relationship between impulsivity and suicidal behavior and the results could place the magnitude of this association into a clearer context. In the second section, we provide a critical review of literature examining the impulsiveness of specific suicide attempts. We show that the general pattern of findings reveals inconsistent definitions of impulsive suicidal behavior, problematic measurements of planning, and a pattern of results incompatible with the notion that suicidal behavior frequently occurs without extensive planning. In the final section of the article, we provide a description of our alternative conceptualization of the association between impulsivity and suicidal behavior and the empirical evidence underlying that conceptualization. Downloaded from psr.sagepub.com at Remen University of China on September 6, 2015

368 Personality and Social Psychology Review 18(4) Meta-Analytic Review of Trait Impulsivity Findings Study Selection Trait impulsivity findings were reviewed meta-analytically. The inclusion criteria were the use of both a measure of suicidal behavior (e.g., non-lethal attempts; death by suicide) and impulsivity. Furthermore, results directly testing an association between impulsivity and suicidal behavior must have been included in the published manuscript. Studies that examined only suicidal ideation or suicide risk or which did not clearly differentiate suicidal behavior from other related variables (e.g., ideation, NSSI) were excluded. Using 53 databases (e.g., Pubmed, PsycInfo), we entered the search terms suicide, suicidal behavior, impulsivity, and impulsive (these same search terms were used to develop our systematic review). After examining the measures utilized in each study, we eliminated any that did not fit our criteria. At that point, we examined each study and excluded any that used our required measures (a measure of trait impulsivity and suicidal behavior) but did not provide results that tested an association between them. In an effort to ensure that our outcome variable was not overly broad, we restricted the studies in the meta-analysis to those that examined the presence/ absence of suicidal behavior or frequency of suicidal behavior. Studies examining characteristics of suicidal behavior (e.g., medical lethality) were excluded. (Results from these and all other trait impulsivity studies, including which measure(s) was used, the nature of the study sample, and the size of the effect(s), can be found in the online Appendix). See Figure 2 for a description of the study selection process. Data Extraction For each study, data relevant for our meta-analysis were retrieved from the original study and entered into the statistical software (described below). When available, the mean and standard deviation for trait impulsivity and sample size for each group (suicidal behavior vs. no suicidal behavior) was recorded for each effect in each study. When such data were not available, odds ratios with 95% confidence intervals, p values with total sample size, or Cohen’s d with sample size were recorded and imputed into the meta-analysis software. Statistical Analysis Data were analyzed using Comprehensive Meta-Analysis (CMA) 2.0 statistical software (Borenstein, Hedges, Higgins, & Rothstein, 2005). Hedges g was utilized to calculate the standardized mean difference on suicidal behavior outcomes, Figure 1. Two models of the relationship between impulsivity and suicidal behavior. Note. In both models, impulsivity is defined as a tendency to act without forethought. Model a: In this more traditionally proposed model, impulsivity is a proximal risk factor, serving as a force or pressure and as such immediately precedes suicidal behavior in response to stress and/or aversive selfawareness (e.g., Baumeister, 1990; Mann, Waternaux, Haas, & Malone, 1999). In this model, there is a narrow window of opportunity and limited targets of opportunity (e.g., impulsivity immediately preceding suicidal behavior). This narrowness serves as an obstacle to clinical interventions aimed at reducing suicide risk and related behaviors. Model b: In this model, impulsivity is a trait that plays a facilitative role in other behaviors (i.e., painful or provocative events), which result in acquired capability. In this model, there is a larger window of opportunity and more targets for interventions aimed at reducing suicide risk and behaviors. Downloaded from psr.sagepub.com at Remen University of China on September 6, 2015

Anestis et al. 369 and we adhered to Cohen’s (1988) description of small (g = .2), medium (g = .5), and large (g = .8) effects. Several studies included multiple effects based on different measures of impulsivity. Some meta-analysis experts have argued that, in such situations, the proper approach is to choose one representative effect from each study to avoid artificially inflating the weight of any study through consideration of inter-related effects (e.g., Cooper, 1998). Others, however, have argued that multiple effects from the same study can be included if authors believe or have evidence to support the possibility that the effects are entirely or almost entirely unrelated to one another (e.g., Gliner, Morgan, & Harmon, 2003). A third approach is to compute a mean effect size across effects within each study and then include only the grand mean value for each (e.g., Connor, Glatt, Lopez, Jackson, & Melloni, 2002). We opted to utilize one effect from each sample, as this appeared to be the most conservative approach and represented the most stringent challenge to our hypothesis (e.g., a single effect from a more psychometrically sound measure may yield a larger effect, which would contradict our hypothesis).1 As a result, our findings represent analyses based on unique samples (e.g., participants were not represented multiple times across individual studies; see Table 1). For studies in which one effect was selected from among several, we made an effort to select the effect that was most representative of the central tendency. In studies in which multiple self-report measures were utilized, we selected the Barratt Impulsiveness Scale (BIS; Patton, Stanford, & Barratt, 1995). Although this might cause the analysis to only reflect one of several conceptualizations of impulsivity, the BIS is by far the most frequently utilized measure in such studies (see online Appendix) and, as such, the analysis would also be the most representative of the literature as it is. Furthermore, analyses focused on any other self-report measure would be underpowered, thereby raising questions regarding the validity of the findings. In studies in which multiple behavioral measures were utilized, we selected the Immediate Memory Task (IMT; Dougherty, Marsh, & Mathias, 2002), as it appeared to maintain the most consistent relationship with suicidal behavior. If these measures were not utilized, we selected the largest effect in an effort to ensure that selections did not artificially weigh results in a direction that might be perceived as consistent with our model (e.g., decreasing the magnitude of the effect across studies). In studies in which both self-report and behavioral measures were used, we selected a behavioral measure based on the assumption that performance on such tasks avoids the drawbacks of self-report (e.g., lack of insight), thereby offering greater construct validity. In addition, in studies in which multiple diagnostic groups were represented (e.g., bipolar disorder and depression), we selected what we deemed to be the more clinically severe diagnostic group (e.g., bipolar disorder). Finally, when one study reported multiple effects on the same measure from multiple comparisons (e.g., multiple Figure 2. Flow chart for studies included and excluded from meta-analysis. Downloaded from psr.sagepub.com at Remen University of China on September 6, 2015

370 Personality and Social Psychology Review18( Table I.Results From Meta-Analyses Examining the Magnitude of the Association Between Trait Impulsivity and Suicidal Behavior. Analysis Type of study Q k df FSN FSZ FS p 4 24401 7 897871 706022 18160000 RE Cross-sectional 37 29.46 889 <001500.89 88.8257 56403 16.60 0000 RE Prospective [02..17] 243 30 3.59 ”sychological autopsy 30【-.13.72] .36 2 7 .0003 6.88 .0000 )we n the analysis in effects (n-7) groups were most Q-tes ating ty a controls)to compare groups that differ primarily on the out the effect size was small (Hedges9,95% come of inter of suicidal behavior)as opposed 17].p=015).There was no evidence that publication bias o othe effects(7)the O-test was signifieant (2112)and the ior is consistent across type of study,we coded each effect as value(95.05)indicated a substantial amount of that variabil s-sectional prospective or psychological autopsy tywas due to hete eity rathe tha The test of nd suicidal hehav mall(Hed as non-s 3000%Cm= 421T ior within each of these grouns was no evidence that publication bias significantly affected Across each meta-ar effect sizes fo each sampl our results were weighted( of the c whether there was substantial heterogeneity of effect sizes Discussion of the Meta-Analytic Review Because we anticipated that effect sizes would vary acros The results indicate that,when considering trait impulsivity studies to use a random ffects(RE)model in eac the relationship is signif To test pub cance of the fail safe test and reported the number of studies and have not engaged in previous non-lethal suicidal behav with non-significant effects that would be required to render the results non-significant etwee uals who d beha Results All meta-analytic results are presented in Table 1. contros,the relationship is not statistically significant,indi ing only 84.82 ect per study (n mpul od by whic It is particularly difficult to reconcile this last point with due to heterogeneity rather than chance.The test of the null models that conceptualize lethal self-harm as often being mall (Hedges g To put such findings into The cted our results. stress disorder,depressed mood,hopelessness,family his When consi ring only cross-sectional effects (n=57),the tory of suicide,and prior suicide attempts(e.g.,Large,Smith was signif cant (500 )and th value (88.82)ind m Singh,2011; Gooding, the te ect sizes h 8hcmassgicantandhceiectscwassma0Hetgs .bulimia nerv and g-37,95%C1 -[29,.46]p<001).There was no evidence e.g motharan,Lange,Zale that publication bias significantly affected our results Exhibiting a less robust 30

370 Personality and Social Psychology Review 18(4) attempters vs. single attempters vs. community controls), we used the suicidal and non-suicidal groups that were most similar to one another (e.g., single attempters vs. community controls) to compare groups that differ primarily on the outcome of interest (presence of suicidal behavior) as opposed to other potential confounding variables. In an effort to assess the degree to which the magnitude of the relationship between trait impulsivity and suicidal behavior is consistent across type of study, we coded each effect as cross-sectional, prospective, or psychological autopsy. Follow-up meta-analyses were run to test the magnitude of the relationship between trait impulsivity and suicidal behavior within each of these groups. Across each meta-analysis, effect sizes for each sample were weighted (for original effect sizes, see online Appendix), and we examined the significance of the Q-test to determine whether there was substantial heterogeneity of effect sizes. Because we anticipated that effect sizes would vary across studies, we opted to use a random effects (RE) model in each analysis. To test for publication bias, we examined funnel plots for each effect. In addition, we examined the significance of the fail safe test and reported the number of studies with non-significant effects that would be required to render the results non-significant. Results All meta-analytic results are presented in Table 1. In our analysis, considering only one effect per study (n = 57), the Q-test was significant (684.82) and the I 2 value (89.78) indicated a substantial amount of that variability was due to heterogeneity rather than chance. The test of the null was significant, and the effect size was small (Hedges g = .34, 95% confidence interval [CI] = [.24, .40], p < .001). There was no evidence that publication bias significantly impacted our results.2 When considering only cross-sectional effects (n = 57), the Q-test was significant (500.89) and the I 2 value (88.82) indicated a substantial amount of that variability was due to heterogeneity rather than chance. For cross-sectional effects, the test of the null was significant and the effect size was small (Hedges g = .37, 95% CI = [.29, .46], p < .001). There was no evidence that publication bias significantly affected our results. In the analysis including only prospective effects (n = 7), the Q-test was non-significant (9.50), indicating homogeneity across effect sizes. The test of the null was significant and the effect size was small (Hedges g = .09, 95% CI = [.02, .17], p = .015). There was no evidence that publication bias significantly affected our results. In our analysis considering only psychological autopsy effects (n = 7), the Q-test was significant (121.12) and the I 2 value (95.05) indicated a substantial amount of that variability was due to heterogeneity rather than chance. The test of the null was non-significant (p = .17) and the effect size was small (Hedges g = .30, 95% CI = [−.13, .72], p = .42). There was no evidence that publication bias significantly affected our results.3 Discussion of the Meta-Analytic Review The results indicate that, when considering trait impulsivity and suicidal behavior in general, the relationship is significant but small in magnitude. This result mirrors those from studies that specifically differentiated individuals who have and have not engaged in previous non-lethal suicidal behavior (cross-sectional) and studies that specifically differentiated between individuals who do or do not engage in suicidal behavior during a follow-up period (prospective). In psychological autopsy samples, however, where investigators attempt to differentiate between suicide decedents and living controls, the relationship is not statistically significant, indicating that trait impulsivity is not a reliable method by which to differentiate those who have and have not died by suicide. It is particularly difficult to reconcile this last point with models that conceptualize lethal self-harm as often being impulsive. To put such findings into context, other metaanalyses have found at least moderate effect sizes for the relationship between suicidal behavior and posttraumatic stress disorder, depressed mood, hopelessness, family history of suicide, and prior suicide attempts (e.g., Large, Smith, Sharma, Nielssen, & Singh, 2011; Panagioti, Gooding, & Tarrier, 2012). Other meta-analyses have found moderate effect sizes between components of impulsivity and pediatric weight status, bulimia nervosa, and problematic alcohol use (e.g., Stautz & Cooper, 2013; Thamotharan, Lange, Zale, Huffhines, & Fields, 2013). Exhibiting a less robust Table 1. Results From Meta-Analyses Examining the Magnitude of the Association Between Trait Impulsivity and Suicidal Behavior. Analysis Type of study g CI z p Q I2 k df FSN FS Z FS p RE 1 effect per study .34 [.24, .40] 9.75 <.001 684.82a 89.78 71 70 6,022 18.16 .0000 RE Cross-sectional .37 [.29, .46] 8.89 <.001 500.89a 88.82 57 56 4,031 16.60 .0000 RE Prospective .09 [.02, .17] 2.43 .015 9.50 36.83 7 6 17 3.59 .0003 RE Psychological autopsy .30 [−.13, .72] 1.36 .17 121.12a 95.05 7 6 80 6.88 .0000 Note. g = Hedges g, CI = 95% confidence interval; FSN = fail safe n; FS Z = Z test for Classic Fail Safe Test; FS p = p value for Classic Fail Safe Test; RE = random effects model; 1 effect per study = one effect selected from any study with more than one effect reported. a Denotes heterogeneity test was significant. Downloaded from psr.sagepub.com at Remen University of China on September 6, 2015