Article Reconsidering the Link Between Impulsivity and Suicidal Behavior SAGE MichaelD.Anestis'Kelly A.Soberay Peter M.Gutierrez Theresa D.Hernandez,and Thomas E.Joiner Abstrac It is widely accepted that suicidal behavior often occurs with little planning.We propose,however,that suicidal behavior i r by p ors capa enn of research considerine the im ts metaanalytic results su trait impulsivity and suicidal behavior is small Furthermore,studies examining a mediating role of painful and provocative review sugest that resear e bee y9 mpts and that measures sensitive to epis pulsivity.acquired capability Suicide is a global concern,resulting in the annual deaths of several subcompo nents (e.g..negative urgency.deficits in approximately one million individua )( planning),nearly all of which involve a tendency to act with ute of Me in mind,rese out forethought(sensation s wg and I perse ha wing list of variables linked to risk,including hopeless 1985),depre vith suicidal be avior.Virtually all of these include refer 10 (e.g. atz Don-su cnce to a c of th Prinstein,2006).thwarted belor and perceived bur For instance.ome researhers posit that the densomeness (oiner.2005).Although the mechanisms elationship is best thought to represent impulsive through which these va ggression,a ter ard othe f with thi d that def able for which this is noter orthy is impulsivity.which has sient serotoninergie neurotransmission re ented by lov ociated with suicidal be avior across erebrospinal fluid 5-hydroxyindolacetic acid(CSF-5HIAA a large of st (e.g.,Dough eny et al 2004) Mann. of thi 2004 Definitions vary in emphasis,with some focusing on the act of engaging risky behavior (e.g. Barratt.193),son Co CO.USA opt IRECC.CO.USA Marsch.2001).and some emphasizing the imp e of cific affective states as influences over an individual's sudden ves to in problemati ors (e.g 2001 he tiesburg MS 39406.USA of ir
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 Review18( (a)Models proposing suicidal behavior is frequently impulsive Proximal Risk Distal Risk Factor (b)Distal risk factor model Acquired Distal Risk Factor (e.g-,Trait Impulsivity Events Capability of the del imp proximal ure and as such imn or in e.g. etodni9portun Model ole in o which ide risk and behaviors Meta-Analytic Review of Trait Impulsivity Findings cacics of u b Study Selection Trait impulsivity findings were reviewed meta-analytically. cffect(s).can be found in the online Appendix).Sce Figure 2 for a description of the study selection process. Data Extraction association between impulsivity and suicidal behavior must For each study,data relevant for our meta-analysis were ve been included in the pation or suicide risk or whien did y variables (e.g ideation.NSSD)were excluded.Using ation fo 53 databases(e.g,Pubmed,Psyclnfo),we entered the sea for each gr p(suicidal behavior vs.no suicidal behavior was recorded for each effect in each study.When such data odds ratios with 95 ese same fte confidence inter erms were u study,we eliminated any that did not fit our criteria.At that eta. oftware point,we examined each study and excluded any that use t trait Statistical Analysis association be them In e that ou come variable was not overly broad,we restricted the studies Meta-Analysis presence Rothstein,2005).Hedges g was utilized to calculate the standardized mean difference on suicidal behavior outcomes, te 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 he incuded in the meta Figure 2.Flow chart for studies included and and we eadhered to Cohen's(198)d scription of small eness (BIS;Patton,Stanford, reflect one of several con ualizations of impulsivity.the impulsivity.Some meta-analysis experts have argued that,in BIS is by far the most frequently utilized measure in such such situations,the proper approach is to choose one repre studies (see online Appendix)and,as such,the analysis be the he effects Cooper.1998)Others.however.have ar sure would be underpowered.thereby raising that multiple effects from the same study can be included if regarding the validity of the findings.In studies in which vioral measures the eeairgoramt Mathi nory la ugherty, anproach is to compute a mean effect size across effects tent relationship with suicidal behavior.If these me sures within each study and then include only the grand mean were not utilized,we selected the largest effect in an effort to Glatt,Lop hat sel ally weigh resu in in a the de( g samnle as this sing the tude e of the effect and the most stringent challenge toour hypoth studies).In studies in which both self-report and behavioral esis (e.g..a single effec from a more psychometrically sound measures were used,we selected a behavioral measure basec me a which would con on th ing greater construct validity.In addition.in studies in which sented multiple time multiple diagnostic groups were represented (e.g..bipolar For studies whi cte rom among disorder ion).we selected what we several L we ma of the ort to In multip self-repor me sures were utilized.we selected the
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
Anestis et al. 371 relationshin with suicidal behavior than the abo erlethality The in relationshin be risk factors does not render the relationship between trait siveness of attempt and lethality of attempt has also been replicated in a sample of adolesc ents (Witte et al,2008). tainly calls into que tudies exa ning the ass ation ort th distal variety of samples.more impulsive attempts were associated with lower depre ssion scores (e.g,Brown,Overholse Critical Review of Studies Examining irito,&Frit 19009,si ner et a 2014 Impulsivity of Attempts Kellv Malone, Mann,2000:Suomine In this sectionwe vide a critical review of findings fro Henriksson,Ostamo,&Lonnqvist,1997;Wojnar et al. studics examining the impulsiveness of specific suicide al.,2007an attempts.We opted against using a meta-analysis in this null cause mea the a reno ion of the article was on the mea and o childhood sexual abuse,and Conner et al.(2006)reporte alization of the impulsivity of attempts.In this sense.there that impulsive attempte were less likely to me was no second va ted that this e s note Sher.2008).and a history of childhood sexual abus of impulsivity of attemnts problematic measuremer )re associated with severe suicidal behav approa are evi with the notion ive plan ning attemnts Wher considered within the context o these find out e. ings,models claiming suicidal behavior frequently occurs Study Selection impulsively are particularly problematic,as such perspec large por and fewer risk factors for severe.repeated.and lethal suicida extent to which participants engaged in suicidal behavi behavior. that involved little to no planning.In some studies,the ed the us sure desigr Conceptual Issues With Studies Examining the siven case Impulsiveness of Specific Suicide Attempts distance of attempt from home)or involved one or m Studies that examine impulsiveness of attempts differ in many ways,including the method of measurement and the attempts considered impulsive.Inst Summary of Results of Studies Examining the d ir %(Houston.Hawton.Sheppard.2001)to(Razin Impulsiveness of Specific Suicide Attempts et al.,1991).As such,there does not appear to be a co nsus In studies that examined the impulsivity of specific suicide as to whether impul a rare phe the gene eral tren appears to argue in greater detail below.we believe the actual p uicideemBac-rd olu20) tion of attempts that can accurately be described as impulsive to be at or very close to 0 omihetisirencofahemgtasmeyamciate on s likel ty ny. ed with which an individual must report having thoughts abou at least once Nakagawa and colleagues (2000)found that attempting suicide.In some studies,participants are asked i less planning was associated with lower lethality.In additior they contemplated eir att mpt for longer tha min pric ner and colleagues( of planning were s from
Anestis et al. 371 relationship with suicidal behavior than the above-mentioned risk factors does not render the relationship between trait impulsivity and suicidal behavior meaningless, but it certainly calls into question its centrality. Indeed, our central thesis is not that trait impulsivity is irrelevant to suicidal behavior but rather that the relationship is indirect and distal. Critical Review of Studies Examining Impulsivity of Attempts In this section, we provide a critical review of findings from studies examining the impulsiveness of specific suicide attempts. We opted against using a meta-analysis in this section because such analyses measure the average strength of the relationship between two variables and the focus of this portion of the article was on the measurement and conceptualization of the impulsivity of attempts. In this sense, there was no second variable to which impulsivity of attempts was being compared. As noted earlier in the article, we anticipated that this review would yield an inconsistent definition of impulsivity of attempts, problematic measurement approaches, and a pattern of results that does not align well with the notion that suicidal behavior frequently occurs without extensive planning. Study Selection Inclusion criteria for studies examined in our critical review involved reporting of any results intended to measure the extent to which participants engaged in suicidal behavior that involved little to no planning. In some studies, the assessment approach involved the use of a measure designed to assess impulsiveness of attempts. In other cases, this included the interpretation of objective circumstances (e.g., distance of attempt from home) or involved one or more questions from within a broader measure. These criteria yielded 49 studies (see Table 2). Summary of Results of Studies Examining the Impulsiveness of Specific Suicide Attempts In studies that examined the impulsivity of specific suicide attempts, the general trend appears to indicate that attempts that involve less planning are associated with less severe outcomes. For instance, in a sample of individuals hospitalized for a suicide attempt, Baca-Garcia and colleagues (2001) found that impulsiveness of attempt was inversely associated with lethality of attempt. Similarly, in a sample of adult inpatients diagnosed with depression who had attempted suicide at least once, Nakagawa and colleagues (2009) found that less planning was associated with lower lethality. In addition, in a sample of 673 attempters, Conner and colleagues (2006) found that greater levels of planning were associated with greater lethality. The inverse relationship between impulsiveness of attempt and lethality of attempt has also been replicated in a sample of adolescents (Witte et al., 2008). Studies examining the association between impulsiveness of attempts and psychopathology also fail to support the view that suicidal behavior is frequently impulsive. Across a variety of samples, more impulsive attempts were associated with lower depression scores (e.g., Brown, Overholser, Spirito, & Fritz, 1991; Conner et al., 2006; Jeon et al., 2010; Nakagawa et al., 2009; Simon et al., 2001; Soloff, Lynch, Kelly, Malone, & Mann, 2000; Suominen, Isometsa, Henriksson, Ostamo, & Lonnqvist, 1997; Wojnar et al., 2009; Wyder & de Leo, 2007; see Conner et al., 2007 and Giegling et al., 2009 for null findings). Similarly, Wojnar et al. (2009) found that impulsive attempters were less likely to report a family history of suicide or having experienced childhood sexual abuse, and Conner et al. (2006) reported that impulsive attempters were less likely to meet diagnostic criteria for substance dependence. Given that depression (e.g., Bostwick & Pankratz, 2000), substance use (Bagge & Sher, 2008), and a history of childhood sexual abuse (e.g., Joiner et al., 2007) are associated with severe suicidal behavior, these findings are evidence that individuals in particularly high-risk groups are less likely to engage in impulsive attempts. When considered within the context of these findings, models claiming suicidal behavior frequently occurs impulsively are particularly problematic, as such perspectives seem to suggest that a large proportion of attempts involve individuals with lower levels of psychopathology and fewer risk factors for severe, repeated, and lethal suicidal behavior. Conceptual Issues With Studies Examining the Impulsiveness of Specific Suicide Attempts Studies that examine impulsiveness of attempts differ in many ways, including the method of measurement and the proportion of attempts considered impulsive. In studies that dichotomized attempts as impulsive or non-impulsive, the proportion of attempts considered impulsive has ranged from 13% (Houston, Hawton, & Sheppard, 2001) to 97% (Razin et al., 1991). As such, there does not appear to be a consensus as to whether impulsive suicidal behavior is a rare phenomenon or representative of the vast majority of attempts. As we argue in greater detail below, we believe the actual proportion of attempts that can accurately be described as impulsive to be at or very close to 0%. One explanation for this large discrepancy is likely the inconsistent operationalization of the time frame during which an individual must report having thoughts about attempting suicide. In some studies, participants are asked if they contemplated their attempt for longer than 15 min prior to attempting (e.g., Hawton, Kingsbury, Steinhardt, James, & Fagg, 1999). In others, the time frame ranges from “none; Downloaded from psr.sagepub.com at Remen University of China on September 6, 2015
372 Personality and Social Psychology Review 18(4) Table 2.Results From Studies Examining Impulsivity of Attempts rL2o00 8 L(200 anley (2010 vell et al (2002 and Burgi d Pass (201 tr0od60 591 tal.(2007 er of SIS Getlao090 ed inte ardt.James.and 833mppe704 Sheppard (2001) 0 gepon d Lamis (2008 O:CIDI .017ta n( ont ofa He.and li (2002) had in ent atte B 114 attempters 40 二 n,and v ar eta 298 260 mpulsive;SIS has been utlized using I item on).2 iton ns (ako 0
372 Personality and Social Psychology Review 18(4) Table 2. Results From Studies Examining Impulsivity of Attempts. Authors Measure of impulsivity Attempt sample % Impulsive Baca-Garcia et al. (2001) 2-item SIS 478 attempters 55.0 Baca-Garcia et al. (2005) 8-item SIS 242 attempters 76.0 Bagge, Glenn, and Lee (2013) 2-item SIS 110 attempters 46.0 Brown, Overholser, Spirito, and Fritz (1991) 2-item SIS 86 adolescent attempters 66.3 Chen et al. (2007) 8-item SIS 148 suicide decedents — Chesin, Jeglic, and Stanley (2010) 8-item SIS 40 BPD attempters — Conner et al. (2005) 7-item SIS 505 suicide decedents 32.0 Conner et al. (2006) Unpublished interview 673 attempters 51.0 Conner et al. (2007) 7-item SIS 117 depressed attempters aged 50+ — Conwell et al. (2002) Presence of loaded and/or unlocked guns in home 50 suicide decedents aged 50+ — de Leo, Cerin, Spathonis, and Burgis (2005) Method unspecified 399 attempters — Deisenhammer et al. (2009) Unnamed number of SIS items 82 attempters 47.6 Dombrovski et al. (2011) 7-item SIS 29 depressed attempters aged 60+ — Fazaa and Page (2011) 2-item SIS 96 undergraduate attempters — Giegling, Hartmann, Moller, and Rujescu (2006) Unnamed number of SIS items 203 attempters 59.1 Giegling et al. (2007) Unnamed number of SIS items 167 attempters + 92 decedents 61.0 Giegling et al. (2008) Unnamed number of SIS items 144 attempters 60.5 Giegling et al. (2009) Unnamed number of SIS items 111 attempters 58.6 Hall, Platt, and Hall (1999) Unstructured interview 100 “severe” attempters — Hawton, Kingsbury, Steinhardt, James, and Fagg (1999) 1 item SIS 45 adolescents hospitalized for intentional overdose 83.3 multiple attempters; 70.4 first time attempters Houston, Hawton, and Sheppard (2001) Inquest notes 27 suicide decedents 13.0 Huan et al. (2004) 2-item SIS 100 attempters 26.0 Jeon et al. (2010) Unpublished interview 208 attempters 36.0 Langhinrichsen-Rohling and Lamis (2008) “Suicide interview” 39 youth attempters 83.0 Mann and Malone (1997) 8-item SIS 22 depressed attempters — Mann et al. (1992) “First part” of SIS 53 attempters 66.7 Mann et al. (1996) 8-item SIS 49 attempters — Miranda et al. (2008) Adolescent suicide interview 79 attempters — Nakagawa et al. (2009) 8-item SIS 151 depressed attempters — Nock et al. (2008) WHO: CIDI 5,017 attempters — O’Donnell, Farmer, and Catalan (1996) Unnamed number of SIS items; proximity to home 20 attempters who had jumped in front of a train — Pearson, Phillips, He, and Ji (2002) Unpublished interview 147 female attempters — Raja and Azzoni (2004) Unpublished questionnaire 80 attempters 48.8 Razin et al. (1991) Unstructured interview 33 female adolescent attempters 97.0 Serretti et al. (2007) Unnamed number of SIS items 167 attempters 61.0 Simon et al. (2001) Unpublished interview 153 “nearly lethal” attempters 24.0 Soloff, Lynch, Kelly, Malone, and Mann (2000) 8-item SIS 92 attempters — Spokas, Wenzel, Brown, and Beck (2012) 1-item SIS 143 attempters 43.3 Stanley, Gameroff, Michalsen, and Mann (2001) Unnamed number of SIS items 53 attempters — Suominen, Isometsa, Henriksson, Ostamo, and Lonnqvist (1997) 2-item SIS 114 attempters 44.0 Verkes et al. (1998) 8-item SIS 144 attempters — Westheide et al. (2008) 8-item SIS 29 depressed attempters — Weyrauch, Roy-Byrne, Katon, and Wilson (2001) 3-item SIS 99 attempters — Williams, Davidson, and Montgomery (1980) Unpublished interview 350 attempters 40.4 Witte et al. (2008) Unpublished interview 5,979 attempters 20.0 Wojnar et al. (2008) and Wojnar et al. (2009) Unpublished interview 154 alcohol dependent attempters 62.0 Wong and Phillips (2009) Unpublished interview 353 female attempters — Wyder and de Leo (2007) Unpublished interview 112 attempters 26.0 Note. — = Author(s) did not dichotomize suicide attempts as impulsive/non-impulsive; SIS has been utilized using 1 item (premeditation), 2 items (also includes active preparation), 3 items (also includes suicide note), 7 items (also includes, isolation, timing, precautions against discovery, final acts in anticipation of death), and 8 items (also includes discussions of thoughts/plans with others). SIS = Suicide Intent Scale; BPD = borderline personality disorder; WHO: CIDI = World Health Organization Composite International Diagnostic Interview. Downloaded from psr.sagepub.com at Remen University of China on September 6, 2015
Anestis et al. 373 et al..1991)to less than 30 min had develoned a suicide plan prior to their attemnt this find (e.Woinar et al 2008).to less than 7 consecutive davs ing could indicate that some individuals spend extensive prior to the attempt(e.g..Conner et a2006).Others con- sider the use of easily accessible means or locations clos 0022 s scenario,an ex ensively planne attemp imity to home is an indicator of an impulsive attempt is par viduals are asked to consider only the moments immediatel ticularly problematic.O'Donnell and colleagues (1996) prior to an attempt,without noting the possibility that ther noted that the vast majority of attempis n ther smple of 2 veloped over me and 1,57 rticinants responding to a telenhone su that these attempts were thus impulsive.Inherent in this didalswihapiorhisionyofsuicidalbethaiorcpcn tha We contend that the very nature of suicidal behavior is fluctuated irregularly prior to their attempt,and ony.% such that little to none of it can truly be conceptualized as reported experiencing no previous suicidal ideation or plan prior to their attempt.Furthermore,in a sample of 105 co es2009 er a su cal pain;Jobes,2006)which requires effortful thought Thus,for suicidal behavior tobe impulsive,it 50%of their sample.However,when assessing suicidal pro he at mo theyd participants ab ut the first cur of thoughts that developed episodically over time rather tha building on one another increasingly over time.These meth odological concems raise an issue regarding the precise not be label an earch tha iods。 the intention of the behavior.To inflict serious enough self. the behavior itself by (a)asking participants to spe ifically they are going to and h ing to do it. the petir imn ately prece atten ents'an spur require much planning and has a high probability of resulting eswere spent planning,thereby priming the individual to the boundary think only about hort me ming a pe the equence that behavior.he or she should not need to reeat this pro he fear of death and massive bodily harm and,as such,we cess immediately prior to the behavior for it to be consid pulsively decide to pick up ere d planned and ntal and/orp to ical gcnenagy For example, those fears sidering the contextual factors that could affect their decision to utilize one approach versus other options.Yet,when sur- Obstacles in Studies Examining Impulsivity of icalPproe Attembts Further complicating the conceptualization of impulsivity as tary,and perhaps impulsive,decision rather than the result it applies to suicidal behavior is a tenden y for studies to ces 1%g or prev the by Conner and colle s(2006)were considered impuls despite the fact that 58%of attempters indicated that they may well be
Anestis et al. 373 impulsive” (e.g., Brown et al., 1991) to less than 30 min (e.g., Wojnar et al., 2008), to less than 7 consecutive days prior to the attempt (e.g., Conner et al., 2006). Others consider the use of easily accessible means or locations close to home as evidence of impulsivity (e.g., Conwell et al., 2002; O’Donnell, Farmer, & Catalan, 1996). The use of close proximity to home is an indicator of an impulsive attempt is particularly problematic. O’Donnell and colleagues (1996) noted that the vast majority of attempts in their sample of 20 attempters who survived jumping in front of a train occurred at the station nearest to the attempter’s home and concluded that these attempts were thus impulsive. Inherent in this viewpoint is the notion that planning a suicide attempt is positively correlated with distance from home, a point that lacks a clear rationale. We contend that the very nature of suicidal behavior is such that little to none of it can truly be conceptualized as impulsive. Although people engage in suicidal behavior for many reasons, they likely boil down to finding a solution to a very serious problem (e.g., ending unbearable psychological pain; Jobes, 2006), which requires effortful thought. Thus, for suicidal behavior to be impulsive, it must occur in the absence of prior planning outside the moments and hours immediately preceding the behavior (i.e., consideration of methods and selecting the one to use). Even if the bulk of the planning occurs sporadically over an extended period long before the attempt and minimally or not at all immediately prior to the attempt, then the behavior should not be labeled impulsive. We are proposing a distinction that accounts for the intention of the behavior. To inflict serious enough selfharm to risk death, people must give very careful thought to what they are going to do and how they are going to do it. A counter-argument could be made that picking up a gun, pointing it at the body, and pulling the trigger does not require much planning and has a high probability of resulting in death without causing pain. In this sense, the boundary typically presented by overcoming pain and a potentially lengthy experience of pain is removed. However, the prospect of shooting oneself nonetheless involves overcoming the fear of death and massive bodily harm and, as such, we believe an individual could impulsively decide to pick up a gun, but would be unable to pull the trigger without enough rehearsal (mental and/or physical) and planning to diminish those fears. Obstacles in Studies Examining Impulsivity of Attempts Further complicating the conceptualization of impulsivity as it applies to suicidal behavior is a tendency for studies to refer to some attempts as impulsive regardless of previous ideation or planning. For instance, 51% of attempts in a study by Conner and colleagues (2006) were considered impulsive despite the fact that 58% of attempters indicated that they had developed a suicide plan prior to their attempt. This finding could indicate that some individuals spend extensive periods of time planning but experience intermittent periods of ideation. In this scenario, an extensively planned attempt may be preceded by a period of mild or even no ideation. In this sense, the findings would be driven by the fact that individuals are asked to consider only the moments immediately prior to an attempt, without noting the possibility that their thoughts developed over time and were episodic in nature. Indeed, de Leo et al. (2005) found that, in a sample of 11,572 participants responding to a telephone survey, only 20% of individuals with a prior history of suicidal behavior experienced risk as a phenomenon that developed consistently and without break, increasing in severity from the beginning to the end. In fact, 57.1% reported that their “suicidal process” fluctuated irregularly prior to their attempt, and only 0.8% reported experiencing no previous suicidal ideation or plan prior to their attempt. Furthermore, in a sample of 105 consecutive patients admitted to an Austrian hospital after a suicide attempt, Deisenhammer and colleagues (2009) reported that the “suicidal process” lasted less than 10 min for nearly 50% of their sample. However, when assessing suicidal process, they asked participants about the “first current emergence of suicidal thoughts,” thereby precluding measurement of thoughts that developed episodically over time rather than building on one another increasingly over time. These methodological concerns raise an issue regarding the precise meaning of an impulsive attempt: Research that measures impulsivity of attempts often overlooks extensive periods of planning and consideration that do not immediately precede the behavior itself by (a) asking participants to specifically consider the period immediately preceding the attempt and (b) framing the time period in a manner that might spuriously influence respondents’ answers (e.g., asking how many minutes were spent planning, thereby priming the individual to think only about a short time frame). If a person already understands the consequences of engaging in a behavior and the steps required to engage in that behavior, he or she should not need to repeat this process immediately prior to the behavior for it to be considered planned and non-impulsive. For example, emergency surgeons spend countless hours developing expertise at specific components of particular surgical procedures and considering the contextual factors that could affect their decision to utilize one approach versus other options. Yet, when surgeons are involved in an actual emergency surgical procedure, their decisions often appear automatic, as if their decision to choose a particular option reflected a momentary, and perhaps impulsive, decision rather than the result of a deliberate process involving practice, prior experiences, and thoughtful planning. Here again, the clinical implications must be noted, as unplanned behaviors may not be preventable, but behaviors planned long before their enactment may well be. Downloaded from psr.sagepub.com at Remen University of China on September 6, 2015
374 Personality and Social Psychology(4) Measurement Issues in Studies Examining would constitute the only impulsive action because this ness of Specific Suicide Attempts oehavior had not been planned an ironic possibility indi ngthat "whim The inconsistent operationalizations of impulsive attempts indicate a potential problem in the measurement of the co d high-letal ts lar t their decision an we tu our attention nich th scale of Beck's Suicide Intent Scale (SIS:Beck 1990:Beck ep sense of regret regar Schuvler.Herman.1974)is the most commonly used mea .they fela de sure for the their decision or contacting help (Bourke,Shapiro,Steel,& ever,th .ha fson,2006). item from the measure,other permutations utilized includ Other items included in var ub note, 3-,7-,and 8-item versions (e.g.,Brown et al. 1991 l et a cated to others about their desire to attempt suicide.Each of hle2 for a all studie with respect to the me urement o 8-item versions of the SIS utilize the same items(e.g.,Baca resp Garcia et al.,2005;Ma Malone 1997).To our know 20051A studi g hat a lack of a note indicates impulsivity is problemati f al h dds of an a port.Indeed,the lack of other established mea ures of thi p by ts a sigr nt obstacle in suicide re ive the iten tcomings SIS Sh. n the impu itself focuses purely on interpersonal actions(e.g. making selection The content of hanges to w rel ome of the items calls into ques tion the validity of th re in the assessment of the mpu hich ind ng th Furthermore.the item overlooks the fact that individuals the SIS Plan mpting suicide feel isolatec fron ers and may subscale with less lation conceptualized as indicating eater This item seems problen becaus ed burd ntaisa belief thatthe nal' ng from death will be worth more than his or her life,implying a a particular public ce (e.g. er,2 5 the Golden Gate Bridge)offers the greatest chance at death and nsively to tilize at loc hought with another r n reflects the degree to which tha Another item utilized in various forms of the Planning ong-term atl on the worl subscale of the SIS ses sthe degree to which an individ indicate and thu mp m vould cont radict the notion of an impulsive attempt ualized as indicating Tellingly,Robins(1981)found that 70%of suicide dece Here again.the relevance of this item to the impulsivity of in the daysbefor n an n argumen Perhat s the most important limitation to the items in the various forms of the Planning subscale of the SIS is the item hat most directly overlaps with othe measure used death In other words if an individual the attempt,enacts the planned method,but feels rush of fear y,one item a during or immediately after this process (an or to the attempt.with the available answers being"impul life-sa the atte sive;no premeditation,""considered for<hr,""considered sive.Instead,the person's efforts to preserve his or her life consider day
374 Personality and Social Psychology Review 18(4) Measurement Issues in Studies Examining Impulsiveness of Specific Suicide Attempts The inconsistent operationalizations of impulsive attempts indicate a potential problem in the measurement of the construct. Therefore, we turn our attention to ways in which the impulsiveness of attempts is measured. The Planning subscale of Beck’s Suicide Intent Scale (SIS; Beck, 1990; Beck, Schuyler, & Herman, 1974) is the most commonly used measure for the assessment of impulsiveness of attempts; however, there is little consistency in the number and selection of items to be used. Whereas some work has used only a single item from the measure, other permutations utilized include 2-, 3-, 7-, and 8-item versions (e.g., Brown et al., 1991; O’Donnell et al., 1996; Verkes et al., 1998; Weyrauch, RoyByrne, Katon, & Wilson, 2001; Wong & Phillips, 2009; see Table 2 for a summary). Furthermore, not all studies using 8-item versions of the SIS utilize the same items (e.g., BacaGarcia et al., 2005; Mann & Malone, 1997). To our knowledge, no studies have been conducted comparing scores on this measure of planning to other such measures, thereby leaving the validity of the subscale without empirical support. Indeed, the lack of other established measures of this construct represents a significant obstacle in suicide research. The shortcomings of the SIS in the assessment of impulsivity of attempts are not limited to inconsistency in item selection. The content of some of the items calls into question the validity of the measure in the assessment of the impulsivity of attempts. For instance, an item assessing the degree to which individuals who attempt suicide do so in isolation from others is often included in the SIS Planning subscale, with less isolation conceptualized as indicating greater impulsivity. This item seems problematic because many highly lethal methods (e.g., jumping from high places) often involve attempting suicide near other people and, if an individual decides that a particular public space (e.g., the Golden Gate Bridge) offers the greatest chance at death and plans extensively to utilize that location, the public nature of the event does not seem relevant to the planning that went into the action itself. Another item utilized in various forms of the Planning subscale of the SIS assesses the degree to which an individual who attempts suicide makes an effort to get help during or after the attempt, with greater help-seeking behavior conceptualized as indicating greater impulsiveness of attempt. Here again, the relevance of this item to the impulsivity of the attempt is unclear. In fact, an argument could be made that, in this scenario, the only impulsive activity is the effort to contact others and preserve life in the face of imminent death. In other words, if an individual thoroughly plans an attempt, enacts the planned method, but feels a rush of fear during or immediately after this process (and this sequence of events does occur regularly), prompting an effort to obtain life-saving assistance, the attempt itself would not be impulsive. Instead, the person’s efforts to preserve his or her life would constitute the only impulsive action because this behavior had not been planned—an ironic possibility indicating that “whims to live” may exist whereas “whims to die” do not. The possibility that individuals who make wellplanned high-lethality attempts lament their decision and “flinch” is supported by the stories of survivors who jump from the Golden Gate Bridge, who have reported that immediately after jumping, they felt a deep sense of regret regarding their actions but were obviously incapable of reversing their decision or contacting help (Bourke, Shapiro, Steel, & Wolfson, 2006). Other items included in various forms of the Planning subscale assess whether individuals left a suicide note, took specific actions in anticipation of their death, or communicated to others about their desire to attempt suicide. Each of these items has significant problems with respect to the measurement of impulsivity as well. With respect to suicide notes, research has indicated that only 20% to 35% of suicide decedents leave notes (e.g., Shioiri et al., 2005). Assuming that a lack of a note indicates impulsivity is problematic because it increases the odds of an attempt being considered impulsive by requiring that a relatively rare behavior (noteleaving) occur for an attempt to be considered non-impulsive. With respect to taking preparatory actions, the item itself focuses purely on interpersonal actions (e.g., making changes to will, taking out insurance) that may not be relevant to some individuals (e.g., individuals without a will or the assets or the legal representation needed to develop one). Furthermore, the item overlooks the fact that individuals attempting suicide typically feel isolated from others and thus may be disinclined to take actions directly related to other people’s well-being (although the construct of perceived burdensomeness entails a belief that the individual’s death will be worth more than his or her life, implying an effort to help others through lethal self-harm; Joiner, 2005). With respect to overt communication, it is simply unclear conceptually how an individual’s decision to discuss a thought with another person reflects the degree to which that thought has been developed over time and considered within the context of its short- and long-term affects on the world. Of course, overt communication days prior to an attempt would clearly indicate significant forethought and thus would contradict the notion of an impulsive attempt. Tellingly, Robins (1981) found that 70% of suicide decedents engaged in such communications in the days before their death, usually more than once. Perhaps the most important limitation to the items in the various forms of the Planning subscale of the SIS is the item that most directly overlaps with other measures used to assess impulsiveness of attempts. Specifically, one item asks how much time was spent considering attempting suicide prior to the attempt, with the available answers being “impulsive; no premeditation,” “considered for 1 day.” Two primary issues render this item less valuable than it may first appear. First, Downloaded from psr.sagepub.com at Remen University of China on September 6, 2015
Anestis et al. 375 xelude the nossibility that ar nitial o rt for the construct validity of the individual extensively considered and planned an attempt long before engaging in the behavior but did not think about directly consider the IPTS model.In a series of studies com Fo ng the pain tole of individu hospita detail during an m an cidental ini from that episode with or without attempting,and then and colleagues (1996)and Orbach.Mikulincer.King.Cohen. attempts suicide in the early portion of a later episode in a and Stein (1997)reported that attempters exhibited higher r entirely c with the earlier plar n tol vell th and thatn out nlan?second hy framing the ansy exhibited greater pain tolerance than did individuals with the four response options involve less than 24 hr,the mea- zero or one prior attempt.Such findings are consistent with sure may push respondents to think about premeditation as the notio that intentionally inflic ing harm onon ppens onl ing the r that the po uals can gradually overcome the fear of discomfort and death asing and decr reasing (or even ceasing entirely)across thro ough deliberate practice)and that a longer history of self different periods but still bustly related to increas shorter time frame with this item,with answers restricted to Prinstein (2005)reported that increased frequ 0("none").1 ("less thar 3 hr"),and 2 ("more than 3 hr") sociated v with pain analgesia during NSSI episodes urth priming up to an atte mpt ( ronic possibility.as non-impulsive greater likelihood of having made a suicide atte attempts would thus still be considered events that were dence for the importance of ain tolerance in the cap pacity for bome of minimal forethought) suicidal behavio one c f these studies Proposed Alternative model of the ences.leaving Relationship Between Impulsivity and open thep pain tole ance acilitat severe self-harming Suicidal Behavior h.the Trait Imbulsivity Efforts tor In contrast to models that conceptualize suicidal behavior as Suicide Scale (ACSS:Be der,Gordon,Bres ner,2011).Using this as( rect (Figure la hav rep mer nel rer s of the ire capability than &。 th by idal b ior,an individual must acquire the capability for suicid ability.men engage in significantly fewer non-lethal sui defined as habituation both to physiological pain and to th attempts fo every lethal attempt than do women,and exposure to pain ary pers suicidal behavior.In this sen the ity te sidering that do not in inflicted gunshot wounds (Anestis&Bryan,2013).Such idly but rather reflects a serie of en with expe findings indicate that certain indiy potentially due to pair s (e. gg of the initial fear e eA R Smith e ward greater pain tolerance and diminished fear.are more evidence that heritability of the acquired capa- able to e engage in lethal suicidal behavior than are others. bility is approximately 65%). who might need to repeatedly engage in low lethality means
Anestis et al. 375 the response scale appears to exclude the possibility that an individual extensively considered and planned an attempt long before engaging in the behavior but did not think about it extensively immediately preceding the attempt. For instance, if an individual plans a suicide attempt with great detail during an episode of elevated suicide risk, recovers from that episode with or without attempting, and then attempts suicide in the early portion of a later episode in a manner entirely consistent with the earlier plan, would this be impulsive or simply reflect the enaction of a well thoughtout plan? Second, by framing the answers such that three of the four response options involve less than 24 hr, the measure may push respondents to think about premeditation as something that happens only during the moments immediately preceding the behavior. This framework does not offer the possibility that premeditation follows an episodic course, increasing and decreasing (or even ceasing entirely) across different periods of time but still building on itself with each progressive episode of contemplation. Importantly, some studies (e.g., O’Donnell et al., 1996) have provided an even shorter time frame with this item, with answers restricted to 0 (“none”), 1 (“less than 3 hr”), and 2 (“more than 3 hr”), further priming individuals to conceptualize planning as something that occurs only in the moments directly leading up to an attempt (another ironic possibility, as non-impulsive attempts would thus still be considered events that were borne of minimal forethought). Proposed Alternative Model of the Relationship Between Impulsivity and Suicidal Behavior Trait Impulsivity In contrast to models that conceptualize suicidal behavior as frequently impulsive and that view the relationship between trait impulsivity and suicidal behavior as direct (Figure 1a), we propose that trait impulsivity is best regarded as one of many distal risk factors for suicidal behavior (see Figure 1b). This proposition is presented through the lens of the interpersonal-psychological theory of suicidal behavior (IPTS; Joiner, 2005). The IPTS proposes that, in addition to desiring death by suicide and/or non-lethal suicidal behavior, an individual must acquire the capability for suicide— defined as habituation both to physiological pain and to the fear of death—through repeated exposure to painful and provocative events before he or she can engage in lethal or near-lethal suicidal behavior. In this sense, the capacity to engage in suicidal behavior does not typically develop rapidly but rather reflects a series of encounters with experiences that alter an individual’s response to pain and impending death, with repeated exposures resulting in a dampening of the initial fear response (see A. R. Smith et al., 2012 for evidence that heritability of the acquired capability is approximately 65%). Initial support for the construct validity of the acquired capability for suicide was reported in studies that did not directly consider the IPTS model. In a series of studies comparing the pain tolerance of individuals who were hospitalized in response to a suicide attempt and individuals admitted to the same emergency room due to accidental injury, Orbach and colleagues (1996) and Orbach, Mikulincer, King, Cohen, and Stein (1997) reported that attempters exhibited higher pain tolerance than did individuals admitted due to accidental injury and that individuals with multiple suicide attempts exhibited greater pain tolerance than did individuals with zero or one prior attempt. Such findings are consistent with the notion that intentionally inflicting harm on oneself has a greater impact on pain tolerance than does accidental injury (thereby providing initial support for the notion that individuals can gradually overcome the fear of discomfort and death through deliberate practice) and that a longer history of selfinflicted injury is more robustly related to increased pain tolerance (providing initial support for the notion that this process unfolds through habituation). Similarly, Nock and Prinstein (2005) reported that increased frequency of NSSI is associated with pain analgesia during NSSI episodes (evidence for habituation), and Nock et al. (2006) reported that pain analgesia during NSSI episodes is associated with a greater likelihood of having made a suicide attempt (evidence for the importance of pain tolerance in the capacity for suicidal behavior). None of these studies utilized longitudinal data demonstrating increases in pain tolerance following repeated engagement in painful and/or provocative experiences, leaving open the possibility that elevated levels of pain tolerance facilitate severe self-harming behaviors entirely different from any habituation process. As such, the research base on this point is not definitive. Efforts to measure the acquired capability directly have centered on the Acquired Capability for Suicide Scale (ACSS; Bender, Gordon, Bresin, & Joiner, 2011). Using this measure, researchers have reported that men report higher mean levels of the acquired capability than do females and military personnel report higher mean levels of the acquired capability than do civilians (including civilians with multiple lifetime suicide attempts; Bryan, Morrow, Anestis, & Joiner, 2010; Van Orden, Witte, Gordon, Bender, & Joiner, 2008). Further supporting the construct validity of the acquired capability, men engage in significantly fewer non-lethal suicide attempts for every lethal attempt than do women, and military personnel engage in significantly fewer non-lethal suicide attempts for every lethal attempt than do civilians, even when considering attempts that do not involve selfinflicted gunshot wounds (Anestis & Bryan, 2013). Such findings indicate that certain individuals, potentially due to their life experiences (e.g., basic training, physical aggression, NSSI) in combination with a genetic predisposition toward greater pain tolerance and diminished fear, are more able to engage in lethal suicidal behavior than are others, who might need to repeatedly engage in low lethality means Downloaded from psr.sagepub.com at Remen University of China on September 6, 2015
