Disinhibitory Trait Profile and Its Relation to Cluster B Personality Disorder Features and Substance Use Problems

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1 European Journal of Personality Eur. J. Pers. 20: (2006) Published online 20 March 2006 in Wiley InterScience ( DOI: /per.585 Disinhibitory Trait Profile and Its Relation to Cluster B Personality Disorder Features and Substance Use Problems JEANETTE TAYLOR*, MARK REEVES, LISA JAMES and LEONARDO BOBADILLA Department of Psychology, Florida State University, USA Abstract Certain personality and motivational traits may present vulnerability towards disinhibitory psychopathology (e.g. antisocial personality disorder, substance abuse). Cluster analysis was used to separately group 306 women and 274 men on impulsivity, Constraint, Negative Emotionality, behavioural activation system (BAS), and behavioural inhibition system (BIS) scores. As expected, a disinhibited group with low Constraint, high impulsivity, weak BIS, and strong BAS emerged that showed elevated drug use problems, and histrionic and antisocial personality disorder features across gender. A high affectivity group with high Negative Emotionality and strong BIS also showed elevated drug use problems and personality disorder features. Results suggested that two different trait profiles are associated with disinhibitory psychopathology and both may present vulnerability toward the development of such disorders. Copyright # 2006 John Wiley & Sons, Ltd. Key words: negative emotionality; disinhibition; Cluster B personality disorders; substance use disorder INTRODUCTION Substance use disorders (SUDs) and antisocial personality disorder (PD) have been referred to as forms of disinhibitory psychopathology, or disorders marked by poor inhibition of impulses possibly stemming from frontal lobe deficits (Gorenstein & Newman, 1980). Models have been put forth to help explain SUDs and/or antisocial PD based on motivational (Fowles, 1980; 1988) and personality traits (Cloninger, Svrakic, & Przybeck, 1993; Depue & Lenzenweger, 2001). Some have proposed that personality traits represent general vulnerability factors that contribute to the risk of developing a mental *Correspondence to: Jeanette Taylor, Department of Psychology, Florida State University, Tallahassee, FL , USA. taylor@psy.fsu.edu Received 22 June 2005 Copyright # 2006 John Wiley & Sons, Ltd. Accepted 17 October 2005

2 272 J. Taylor et al. disorder (Krueger, McGue, & Iacono, 2001b). By extension, it seems possible that what we will call a disinhibitory trait profile exists in the general population and may serve as a vulnerability factor for disinhibitory psychopathology. Thus, the first goal of the present study was to see if a disinhibitory trait profile emerged in a large, non-clinical sample of men and women and whether that profile was associated with elevated levels of SUD and antisocial PD features to gain additional insights about traits that might convey vulnerability towards disinhibitory disorders. In addition, PDs grouped with antisocial PD into Cluster B (specifically, borderline, narcissistic and histrionic PD) are described as erratic and dramatic (APA, 2000) and most have features marked by poorly controlled behaviour (i.e. disinhibition). As indicated below, research suggests that certain personality traits associated with antisocial PD and SUDs are associated with some of the other Cluster B PDs, raising the possibility that a trait profile associated with disinhibitory disorders might also be associated with (and perhaps convey risk toward) other Cluster B PDs. Consequently, the second goal of the present study was to examine the association of trait profiles to Cluster B PDs other than antisocial PD to gain new insights into the profile(s) that might reflect vulnerability toward PDs that have conceptual and empirical associations with antisocial PD and SUDs but have not been widely studied in terms of associated personality and motivational traits. The literature points to several trait dimensions that might be part of a disinhibitory trait profile. These include three personality trait dimensions (impulsivity, Constraint and Negative Emotionality) that have been theoretically and/or empirically linked to disinhibitory disorders such as antisocial PD and/or SUDs. The first of these personality traits, impulsivity, has strong empirical links to disinhibitory psychopathology and is proposed to be a key feature of such disorders (Gorenstein & Newman, 1980). In addition, impulsivity has been proposed as a core feature of Cluster B PDs (Cloninger, 2000). Individuals with SUDs, antisocial PD, and borderline PD score high on measures of impulsivity (e.g. Dougherty, Bjork, Huckabee, Moeller, & Swann, 1999; Fossati et al., 2004; Moeller et al., 2002), and Casillas and Clark (2002) found that impulsivity was at least moderately related to all Cluster B PDs. Thus, both theoretical and empirical bases exist for the expectation that impulsivity would be a likely component of a disinhibitory trait profile. The literature also supports the expectation that Constraint (reflecting attitudes towards social norms, level of behavioural control, and preference for risky activities) might be a component of a disinhibitory trait profile. Low Constraint has been proposed as a vulnerability factor for externalizing disorders including antisocial PD and SUDs (Krueger, Hicks, & McGue, 2001a). Depue and Lenzenweger (2001) proposed that low Constraint is a neurobiological personality dimension that underlies the Cluster B PDs (except narcissistic PD). Empirical evidence consistently supports a connection between low Constraint and both antisocial PD (Krueger et al., 2001a,b; Verona, Patrick, & Joiner, 2001) and SUDs (Conway, Swendsen, Rounsaville, & Merikangas, 2002; McGue, Slutske, & Iacono, 1999; McGue, Slutske, Taylor, & Iacono, 1997). However, the theoretical association between low Constraint and other Cluster B PDs awaits empirical confirmation, which the present investigation will attempt to provide. In addition to impulsivity and Constraint, some evidence (although less consistent) suggests that the personality trait Negative Emotionality (reflecting mood lability, stress reactivity and proneness towards negative emotions) is positively associated with SUDs and antisocial PD and might therefore be part of a disinhibited trait profile. The evidence is mixed regarding an association between high Negative Emotionality and antisocial PD

3 Disinhibitory trait profile 273 (Krueger et al., 2001b; Verona et al., 2001). However, Hicks, Markon, Patrick, Krueger, and Newman (2004) found a differential association of Negative Emotionality to subtypes of psychopathy (an antisocial behaviour disorder that includes many features of antisocial PD), wherein, only the aggressive subtype showed high Negative Emotionality (and low Constraint). Similarly, some studies have demonstrated that people with SUDs have significantly higher Negative Emotionality compared to controls (McGue, Slutske, Taylor, & Iacono, 1997; McGue, Slutske, & Iacono, 1999); a link also supported by a report of their longitudinal association (McGue et al., 1999). However, that finding is not universal (e.g. see Conway et al., 2002). Like Constraint, Negative Emotionality has not been widely studied in relation to Cluster B PDs other than antisocial PD and the present study will begin to address this gap in the literature. The literature reviewed suggests that personality traits such as impulsivity, Constraint and Negative Emotionality are associated with SUDs and various Cluster B PDs, but personality traits alone may not capture the complex mix of psychological features that contribute to disinhibitory disorders. Thus, a disinhibitory trait profile might also include motivational trait dimensions such as behavioural activation and behavioural inhibition, which have also been theoretically and/or empirically linked to disinhibitory disorders. These two motivational dimensions come from Fowles (1980, 1988) psychobiological model of psychopathology based on motivational systems put forth by Gray (1975, 1987). The behavioural inhibition system (BIS) and behavioural activation system (BAS) dimensions reflect behavioural patterns that occur specifically in response to punishment and reward cues, respectively. According to Fowles (1980, 1988), a weak BIS and a strong BAS characterize disinhibitory disorders such as SUDs and antisocial PD. The clinical features of borderline PD (impulsivity, affective instability) would suggest that it might have a BIS/BAS pattern similar to SUDs and antisocial PD. Histrionic and narcissistic PD are marked more by dramatic than erratic or impulsive behaviour per se and, therefore, may show a different BIS/BAS pattern than borderline and antisocial PD. Research examining these possibilities is lacking, and the present study will provide novel information about the relation of BIS and BAS dimensions to borderline, histrionic and narcissistic PD. In summary, research indicates that high impulsivity, low Constraint, weak BIS, strong BAS and perhaps high Negative Emotionality are individual traits associated with SUDs and antisocial PD. However, an association found between an individual trait and a disorder does not speak to the potentially different multi-trait profiles associated with the disorder that, if known, might be informative. For example, SUDs are associated with low Constraint, but that low Constraint score might be coupled with high Negative Emotionality and strong BIS in some cases (where substances may be used in excess to reduce negative affect or anxiety) but with low or average Negative Emotionality and weak BIS in other cases (where substances may be used in excess due to an inability to inhibit use despite negative consequences). Past research suggests that personality traits are differentially associated with antisocial subtypes (e.g. Hicks et al., 2004) and alcoholics (e.g. Cloninger, 1987a, 1987b), suggesting that different trait profiles convey vulnerability towards these disorders. The two goals of the present study were aimed at extending the literature on traits associated with SUDs and antisocial PD. Our first goal was to see if a disinhibitory trait profile existed in unselected young adults and whether such a profile was associated with elevated levels of SUD and antisocial PD features. We accomplished this goal using cluster analysis to empirically group participants according to trait impulsivity, Constraint,

4 274 J. Taylor et al. Negative Emotionality, BIS, and BAS scores and then compared groups on self-reported alcohol and drug problems and antisocial PD symptoms. Our second goal was to examine the association of trait profiles to features of other Cluster B PDs. This would provide new insights into the profile(s) that might convey vulnerability toward PDs that have conceptual and empirical associations with antisocial PD and SUDs but have not been widely studied in terms of associated personality and motivational traits. Following from the reviewed literature on personality and motivational traits associated with disinhibited psychopathology, we expected the cluster analysis to identify a group characterized by a disinhibitory trait profile consisting of high impulsivity, low Constraint, high Negative Emotionality, low BIS, and high BAS scores. Consistent with reviewed literature on SUDs and Cluster B PDs we expected that this disinhibited group would show high levels of antisocial, borderline and histrionic PD features as well as high levels of alcohol problems and drug problems. Consistent with the theoretical proposal by Depue and Lenzenweger (2001) that narcissism is not associated with the same personality profile as the other Cluster B PDs, we did not expect the disinhibited group to be high in narcissistic PD features. We took an exploratory approach to the cluster analysis that allowed for any number of groups to emerge and also allowed for a falsification of our expectation of a disinhibited group. METHOD Participants Participants were 617 (316 women) students aged years (M ¼ 19.18; SD ¼ 1.36) attending a large southeastern US university who volunteered for this study and received introductory psychology class credit for their participation (alternatively, students could meet their course research requirement by writing a paper). Due to a computer programme problem, race/ethnicity data was only available for the first 303 participants in the sample. Based on these 303 participants (105 men; 198 women), the majority of the sample was White (73.9%), African American (8.5%), or Hispanic/Latino (8.2%). The mean age of the sample was (SD ¼ 1.35). Informed written consent was obtained from each participant prior to beginning any procedures and the university IRB approved the study. Procedures and measures Participants completed a series of questionnaires during a 2-hour session. Initially, participants completed paper-and-pencil measures but all measures were then transformed for completion via a computerized Web-based interface. Research suggests that these formats yield comparable data (Davis, 1999; Finegan & Allen, 1994), and analyses comparing participants who received paper versus computer administered questionnaires showed no significant differences on any of the variables included in this study. Clustering variables The Multidimensional Personality Questionnaire-Brief Form (MPQ-BF; Patrick, Curtin, & Tellegen, 2002) is a 155-item abbreviated version of the MPQ (Tellegen, 2000). The MPQ-BF, like the original MPQ, provides a measurement of 11 lower order personality

5 Disinhibitory trait profile 275 traits (e.g. Well Being) that map onto 3 higher order factors: Positive Emotionality, Negative Emotionality and Constraint. Alpha reliabilities for the personality scales ranged from 0.75 to 0.84 (Patrick et al.). The MPQ-BF also includes two validity scales that assess random and inconsistent responding. Raw scores on the MPQ were transformed to T- scores (M ¼ 50; SD ¼ 10) on the entire sample of men and women and the T-scores for Negative Emotionality and Constraint were used as clustering variables. The Barratt Impulsiveness Scale (BIS-11; Patton, Stanford, & Barratt, 1995) contains 30 items rated on a scale from 1 (Rarely or Never) to 4 (Almost Always or Always). In this study, the total score was used as a broad measure of trait impulsiveness. Total scores on the Barratt Impulsiveness Scale have shown good internal consistency (alpha > 0.78) across normal, clinical and criminal samples (Patton et al.). To avoid confusion with the behavioural inactivation system (BIS), the Barratt Impulsiveness Scale will be referred to as Impulsiveness instead of BIS-11. The Sensitivity to Punishment and Sensitivity to Reward Questionnaire (SPSRQ; (Torrubia, Ávila, Moltó, & Caseras, 2001) was developed to tap BIS and BAS functioning and it consists of 24 yes/no statements that comprise the Sensitivity to Punishment scale and 24 that comprise the Sensitivity to Reward scale. The Sensitivity to Punishment and Sensitivity to Reward scales have good test-retest reliability after three months (0.89 and 0.87, respectively) and after one year (0.74 and 0.69, respectively) (Torrubia et al.). Internal consistency for the Sensitivity to Punishment and Sensitivity to Reward scales is also good for both women (0.82 and 0.75, respectively) and men (0.83 and 0.78, respectively) (Torrubia et al.). Finally, the Sensitivity to Punishment and Sensitivity to Reward scales are orthogonal factors with a correlation of less than 0.08 (Torrubia et al.). Substance use problems and personality disorder symptoms The Short Michigan Alcohol Screening Test (SMAST; Selzer, Vinokur, & Rooijen, 1975) was used to assess alcohol use problems. The SMAST consists of 13 yes/no questions that indicate problematic alcohol use. Internal consistency reliability of the SMAST is 0.76 or higher (Selzer et al.). A score of 3 or more on the SMAST indicates alcoholism, but the total SMAST score was used instead as a continuous measure of alcohol use problems. The Drug Abuse Screening Test (DAST; Skinner, 1982) consists of 28 yes/no questions assessing problematic drug use. One-year test-retest reliability of the 20-item version of the DAST is good (0.78; Cocco & Carey, 1998). A score of six or more on the DAST indicates probable drug abuse, but the total DAST score was used as a continuous measure of drug use problems in this study. The Structured Clinical Interview for DSM-IV Axis II Personality Questionnaire (SCID-II-Q; First, Gibbon, Spitzer, Williams, & Benjamin, 1997) is a 119-item measure (with a yes/no format) assessing features of 10 PDs, including the Cluster B PDs examined in this study. The SCID-II-Q does not include the 7 antisocial PD criteria. Therefore, the SCID-II-Q was supplemented with the antisocial PD items from the Personality Diagnostic Questionnaire, 4th edition (PDQ-IV; Hyler et al., 1988). The SCID-II-Q shows high agreement with the SCID-II semi-structured interview (First et al.). A study of the DSM-III-R version of the SCID-II-Q showed internal consistency reliabilities of 0.51 to 0.76 and significant 1-year temporal stability coefficients (0.48 to 0.76) for the Cluster B disorders (Ball, Rounsaville, Tennen, & Kranzler, 2001). Each diagnostic scale consists of between 7 and 13 items and, in some cases, more than one item taps a single

6 276 J. Taylor et al. symptom. Summing the unique symptoms that were endorsed derived a symptom count for each Cluster B PD. The borderline, antisocial and narcissistic PD totals reflected the full range of symptoms for each of those disorders. The histrionic PD total had a maximum of 6 items with the symptoms of seductiveness and impressionistic speech missing from the count because they are typically rated by observation and they were not assessed on the SCID-II-Q. Analyses Cluster analysis was used to derive groups of participants based on personality and motivational traits. Given the sensitivity of cluster analysis to differences in measurement scale (Hair & Black, 2000), all clustering variables were scaled as T-scores on the entire sample as a means of standardization. Significant gender differences were evident for Negative Emotionality, Constraint, and Impulsiveness in this sample and, as such, the sample was split by gender for analyses. Finally, cluster analysis is sensitive to outliers (Hair & Black) and, therefore, univariate outliers were assigned a value equal to twice the interquartile range from the median to preserve their rank in the distribution and avoid losing observations and multivariate outliers were eliminated. The female and male samples were each submitted to a hierarchical cluster analysis using Ward s method with the squared Euclidean distance as the proximity measure. Next, a range of reasonable cluster solutions were identified (based on the dendrogram and agglomeration schedule) and then obtained using K means analyses. A final solution was then selected based its interpretability. In order to examine the validity of the cluster solutions, the male and female samples were randomly split into two samples. In sample 1 within each gender, a cluster solution was obtained using the procedure noted above. In sample 2 within each gender, a cluster solution was obtained using a K means analysis seeded with the centroids from sample 1. Next, the classification of cases from the entire sample was compared to the classification of cases in each of the two subsamples using the kappa statistic. Finally, the number of cases classified into each cluster across samples 1 and 2 within each gender was compared using chi-square tests with a non-significant test indicating a similar proportion of cases being classified into the identified clusters across samples. Alpha was set to 0.05 for the chi-square tests. To examine the relation of trait profiles derived from the cluster analyses to differences in levels of Cluster B PD features and substance use problems, a factorial ANOVA was applied to the entire sample with sample (1 vs. 2), group (N levels based on the outcome of the cluster analysis), and the sample group interaction as factors and drugs (DAST), alcohol (SMAST), antisocial PD, borderline PD, narcissistic PD and histrionic PD total scores as the dependent variables. The sample group interaction was included as an additional check on the validity of the clusters (which should produce a similar pattern of scores on dependent variables across samples if the solutions are truly comparable). To help control for experiment-wise error in the omnibus ANOVA analyses, the dependent variables were grouped conceptually and alpha was corrected within those groupings. The drugs and alcohol scores were grouped as SUD measures and alpha was set at (0.05/2) for those tests; the Cluster B PD scores were grouped as PD measures and alpha was set at Significant main effects for group were followed by relatively conservative post-hoc Tukey s Honestly Significant Difference tests (when variances were equal across groups) or Tamhane s tests (when variances were unequal across groups) with alpha set to 0.05.

7 Disinhibitory trait profile 277 RESULTS The validity scales of the MPQ indicated that 37 of the 617 participants provided invalid data and they were omitted yielding 580 participants (306 women; 274 men) for the analyses. Table 1 presents the means and standard deviations for all variables by gender. Men endorsed more drug and alcohol problems and more antisocial PD symptoms than women. Although we used a non-clinical sample, it was possible that some participants met criteria for an SUD and/or a PD. The level of possible pathology in the sample was estimated by calculating the percent of men and women who self-reported the minimum number of symptoms required for diagnosis on the dependent variables (see Table 1). Table 2 presents the correlations among the clustering variables by gender. Given the large sample sizes, almost all of the correlations were statistically significant even though most were modest in magnitude. The modest magnitude of the correlations supported the idea that motivational traits (BIS and BAS) were related to but not redundant with the personality traits, supporting our inclusion of both types of traits in the cluster analyses. Cluster analyses Cluster analyses conducted on the entire sample of women resulted in a 5-cluster solution. Analyses produced a 4-cluster solution from the entire sample of men, suggesting that we proceed separately by gender. Two women and five men were missing scores on at least one of the clustering variables leaving 151 women and 132 men in sample 1. After splitting the samples, a 5-cluster solution was selected in sample 1 of women and a 4-cluster solution was selected in sample 1 of men, and solutions were then derived from sample 2 within each gender. The validity of the cluster solutions was largely supported. Kappa was 0.81 when classification from the entire sample of women was compared to sample 1 of Table 1. Means (and standard deviations) for clustering variables and dependent variables and percent meeting diagnostic thresholds on dependent variables by gender Variable Mean (SD) Women (N ¼ 306) Men (N ¼ 274) Negative Emotionality (T-score) (9.16) (9.93) Constraint (T-score) (9.39) (9.49) Barratt Impulsiveness Scale (T-score) (10.42) (8.71) Sensitivity to Punishment (T-score) (10.08) (9.48) Sensitivity to Reward (T-score) (9.51) (9.28) Mean (SD) % Meet Mean (SD) % Meet Threshold Threshold Short Michigan Alcohol Screening Test 1.54 (1.19) 15% 1.88 (1.76) 37% Drug Abuse Screening Test 3.00 (3.25) 15% 4.33 (4.46) 30% Histrionic Personality Disorder 2.77 (1.60) 14% 2.57 (1.52) 12% Narcissistic Personality Disorder 4.04 (1.78) 37% 4.26 (1.92) 47% Borderline Personality Disorder 3.32 (2.40) 30% 3.17 (2.08) 25% Antisocial Personality Disorder 1.09 (1.28) 5% 1.59 (1.43) 12% Note: Thresholds: Short Michigan Alcohol Screening Test ¼ 3; Drub Abuse Screening Test ¼ 6; Histrionic ¼ 5; Narcissistic ¼ 5; Borderline ¼ 5; Antisocial ¼ 3; Conduct Disorder ¼ 3.

8 278 J. Taylor et al. Table 2. Pearson correlations among the clustering variables by gender Negative Constraint Impulsiveness Sensitivity to Sensitivity Emotionality Punishment to Reward Negative Emotionality Constraint Impulsiveness Sensitivity to Punishment Sensitivity to Reward Note: Correlations for women are shown below the diagonal and correlations for men are shown above the diagonal. All correlations except the one between Negative Emotionality and Constraint and the one between Sensitivity to Punishment and Sensitivity to Reward are significant at p < Impulsiveness ¼ Barratt Impulsiveness Scale (total score). women and also 0.81 when compared to sample 2. Agreement in the sample of men was not as high: kappa was 0.54 between sample 1 and the entire sample and only 0.46 between sample 2 and the entire sample of men. However, the chi-square analyses showed no significant difference (at the selected p < 0.05 and also when considering a more lenient p of 0.10) in the number of cases classified into each cluster across samples 1 in 2 for either gender. As illustrated in Figures 1a and 2a, both the 5-cluster solution for the women and the 4-cluster solution for the men contained the expected disinhibited group marked by low Constraint, high Impulsiveness, low Sensitivity to Punishment (weak BIS), and high Sensitivity to Reward (strong BAS). The two solutions also contained a high affectivity group, which was defined by high Negative Emotionality, high Sensitivity to Punishment in men but was coupled with high Impulsiveness in women, which prompted us to label the group high affectivity/impulsive in women to reflect this important difference from the men. A relatively average group without clear elevations on any variable was found in both men and women as was a group marked by relatively high scores on Constraint and low scores on all other variables and this group was labelled low affectivity/restrained. Finally, women evidenced a group not found in men that was marked by high Constraint, low Impulsiveness, and high Sensitivity to Punishment, which was labelled constrained. Although there were clear similarities across gender, the differences that emerged seemed potentially interesting and, therefore, we continued analyzing the data separately by gender. Association with substance use problems and personality disorder features The distribution of each dependent variable was normal after bringing univariate outliers to within twice the interquartile range of the median. None of the sample group interactions was significant, lending additional support to the validity of the cluster solutions. For men, a significant ( p ¼ 0.01) main effect for sample was found for drugs, F (1, 259) ¼ 7.03, such that sample 2 had a higher mean than sample 1. Figure 1b presents the means for each group on each dependent variable for women. Consistent with our hypothesis, the disinhibited group showed higher levels of drug problems and antisocial and histrionic PD (but not narcissistic PD) symptoms compared to some other groups. Contrary to expectations, the disinhibited group did not show an increased number of borderline PD symptoms, and the main effect for group was

9 Disinhibitory trait profile 279 Figure 1. Group elevations on clustering variables and mean ( 1 SE) level of substance use and personality disorder symptoms in women; (a) Group elevations on clustering variables. (b) Substance use and personality disorder features in each group. non-significant for alcohol. Among women, the range and mean effect sizes for significant group differences were as follows: drugs (d ¼ ; MEAN d ¼ 0.90); histrionic PD (d ¼ ; mean d ¼ 0.92); narcissistic PD (d ¼ ; mean d ¼ 0.78); borderline PD (d ¼ ; mean d ¼ 1.02); antisocial PD (d ¼ ; mean d ¼ 1.29). Figure 2b presents the means for each group on each dependent variable for men. As expected, the disinhibited group showed the greatest level of drug use problems and

10 280 J. Taylor et al. Figure 2. Group elevations on clustering variables and mean ( 1 SE) level of substance use and personality disorder symptoms in men; (a) Group elevations on clustering variables. (b) Substance use and personality disorder features in each group. histrionic and antisocial PD symptoms. Contrary to expectations, the disinhibited group was also high on narcissistic PD and the main effect of group was non-significant for alcohol. The range and mean effect sizes for significant group differences among men were as follows: drugs (d ¼ ; MEAN d ¼ 0.71); histrionic PD (d ¼ ; mean d ¼ 0.69); narcissistic PD (d ¼ ; mean d ¼ 0.93); borderline PD (d ¼ ; MEAN d ¼ 0.91); and antisocial PD (d ¼ ; MEAN d ¼ 1.06). Differences between groups were medium to large for all variables across gender based on guidelines from Cohen (1988).

11 Disinhibitory trait profile 281 DISCUSSION Models based on personality and motivational traits have been proposed to explain SUDs and antisocial PD (forms of disinhibitory psychopathology). Antisocial PD has descriptive features (e.g. poor behavioural control) in common with other Cluster B PDs, and other Cluster B PDs show similar relations to personality traits like impulsivity. The first goal of the present study was to determine whether a disinhibitory trait profile existed in a nonclinical sample and whether that profile was associated with elevated levels of SUD and antisocial PD features. The second goal was to determine whether such a profile was also related to features of other Cluster B PDs, which are conceptually and empirically related to SUDs and antisocial PD, but are not widely understood with regard to personality and motivational trait correlates. Regarding our first goal, a disinhibitory trait profile did emerge as expected among both men and women with most of the hypothesized features (low Constraint, high impulsivity, low BIS and elevated BAS). However, neither gender showed high Negative Emotionality as part of that profile. Instead, high Negative Emotionality was a key feature of another trait profile that emerged, the high affectivity profile found within each gender. Interestingly, the disinhibited and high affectivity profiles were the only ones marked by higher Negative Emotionality relative to Constraint (with each profile evidencing a roughly 10-point, or one SD, split on those scores). That pattern of MPQ scores is associated with SUDs (McGue et al., 1997; McGue et al., 1999) and antisocial PD (Verona et al., 2001), and the results of the present study suggest that the combination of higher Negative Emotionality relative to Constraint is not a unique trait profile but is instead a component of two different trait profiles in the population. Our findings of a disinhibitory trait profile among a non-clinical sample and an association of that profile to high levels of illicit drug problems and antisocial PD symptoms across gender were consistent with the idea that such a profile exists in the population and might provide vulnerability toward disinhibitory disorders. However, the high affectivity groups reported similarly high levels of drug problems as the disinhibited groups across gender, suggesting that two different trait profiles might convey risk for drug use disorders. Women in the high affectivity/impulsive group also had equally high numbers of antisocial PD symptoms as women in the disinhibited group. These findings require replication but appear to suggest that, particularly in women, disinhibitory psychopathology might arise under two different constellations of personality and motivational traits. As noted above, the common feature of the high affectivity and the disinhibited profiles was the higher Negative Emotionality/lower Constraint score combination, which may have accounted for the association of both trait profiles to drug use problems. Contrary to our expectation, there was no main effect for cluster group membership for alcohol use problems among men or women. Replication of the results with a communitybased non-clinical sample could help clarify the interpretation of these null findings. One possibility is that drinking levels were high in our college-based sample, which may have decreased the variability in alcohol problems among participants. The substantially lower SD found for the alcohol as compared to the drug use problem measure provides some support for this interpretation. Our second goal was to examine the extent to which other Cluster B PDs were associated with a disinhibitory trait profile. Our hypothesis that such a profile would be associated with the highest levels of borderline and histrionic PDs, but not narcissistic PD,

12 282 J. Taylor et al. was only partly supported and results differed by gender. Among women, the disinhibitory trait profile was associated with high levels of histrionic PD features but not borderline or narcissistic PD features, which were associated instead with the high affectivity/impulsive profile. Among men, the disinhibitory trait profile was associated with high levels of features of all Cluster B PDs, but borderline and narcissistic PD features were also high in the high affectivity group. The common features of the high affectivity profile across gender were very high Negative Emotionality (with relatively lower Constraint) and strong BIS functioning, suggesting that this combination of personality and motivational traits might be particularly relevant to the development of narcissistic and borderline PD features. This is consistent with Linehan s (1993) suggestion that emotional dysregulation is the key underlying feature of borderline PD. However, men in the disinhibited group also showed a relatively high level of borderline PD features, indicating that something other than emotional dysregulation is at work in producing borderline PD features in some proportion of men. Taken together, the results suggested that a disinhibitory trait profile might convey risk for drug problems and symptoms of all Cluster B PDs in men, but risk for a particular SUD or Cluster B PD in women may depend on which trait profile is present. The cluster analysis produced what was labelled an average group but, at first glance, that group did not appear particularly healthy in the sample of women. Across gender, the low affectivity/restrained group showed the lowest levels of substance use problems and Cluster B PD features, which were matched by the average group in men and generally by the constrained group in women. In women, the average group was typically intermediate in level of substance use problems and Cluster B PD features, but did not differ significantly from the disinhibited and high affectivity/impulsive groups. Examination of the pattern of means across groups in women (see Figure 1b) suggested that having a constrained or a low affectivity/restrained trait profile may provide some protection against substance use problems and Cluster B PD features as those groups were consistently lowest on each dependent variable. Notable strengths of the present study included the large sample that provided an opportunity to validate the cluster solutions separately by gender and the racial/ethnic diversity of the sample that enhanced the generalizability of the findings. One aim of the study was to examine whether a disinhibitory trait profile existed in people who were not already diagnosed with antisocial PD or SUD, which supported our use of a non-clinical instead of a clinical sample. Nonetheless, there may be important differences between our non-clinical college sample and non-student samples that would impact the generalizability of our findings to non-clinical populations more generally. For example, our use of a higher functioning non-clinical sample could have limited the range of SUD and PD features (although descriptive data suggested reasonable variability in the number of PD symptoms endorsed). Moreover, the personality profiles found in this study were identified via cluster analysis and a different data set (even from another college sample) may produce somewhat different cluster profiles. Furthermore, the lack of association of the personality profiles with alcohol use problems may generalize to other college samples that show high rates of alcohol use but might not generalize to non-student samples in which alcohol use is not as widespread (where the expected associations between certain personality profiles and alcohol use problems might be found). Finally, participants were young adults whose personality traits and PD features may still be under pressures of development that could lead to changes in both trait personality levels and PD features. As such, the present results may not hold for older adult samples where personality traits are more stable and PD features are more ingrained. Two additional limitations also bear

13 Disinhibitory trait profile 283 mention. First, as is often the case in large survey studies, variables were assessed via selfreport raising the possibility that the associations found between groups and the dependent measures owed, in part, to shared method variance. Second, we recognize that using a valid, reliable self-report screener to measure PD features was expedient in obtaining data from over 600 people, but it was not optimal from a purely clinical standpoint. As such, future studies aimed at replicating the present findings would benefit from the use of clinical interviews to assess SUD and PD symptoms. The present results provide initial evidence for the existence of a disinhibitory trait profile in the population that might present vulnerability towards disinhibitory disorders as well Cluster B PDs. Future research should explore how Cluster B PDs other than antisocial may fit into the theory of disinhibitory psychopathology to provide a potentially unifying framework for those disorders. The results also highlight the potential for gender differences in the vulnerability toward SUDs and Cluster B PDs and suggest a need for additional research that explores different pathways to disinhibitory disorders. Finally, the present results suggest that traits related to personality and motivation are relevant in defining a disinhibitory trait profile and future research should examine the relative contribution of each of these profile variables to predicting individual differences in symptoms and diagnoses of SUDs and Cluster B PDs to improve our understanding of the particular traits that might convey vulnerability towards those disorders. REFERENCES American Psychiatric Association. (2000). Diagnostic and statistical manual of mental disorders text revision (4th ed.). Washington, DC: Author. Ball, S. A., Rounsaville, B. J., Tennen, H., & Kranzler, H. R. (2001). Reliability of personality disorder symptoms and personality traits in substance-dependent inpatients. Journal of Abnormal Psychology, 110, Casillas, A., & Clark, L. A. (2002). Dependency, impulsivity, and self-harm: Traits hypothesized to underlie the association between Cluster B personality and substance use disorders. Journal of Personality Disorders, 16, Cloninger, C. R. (1987a). Neurogenetic adaptive mechanisms in alcoholism. Science, 236, Cloninger, C. R. (1987b). A systematic method for clinical description and classification of personality variants. Archives of General Psychiatry, 44, Cloninger, C. R. (2000). A practical way to diagnosis personality disorder: A proposal. Journal of Personality Disorders, 14, Cloninger, C. R., Svrakic, D. M., & Przybeck, T. R. (1993). A psychobiological model of temperament and character. Archives of General Psychiatry, 50, Cocco, K. M., & Carey, K. B. (1998). Psychometric properties of the Drug Abuse Screening Test in psychiatric outpatients. Psychological Assessment, 10, Cohen, J. (1988). Statistical power analysis for the behavioral sciences (2nd ed.). Hillsdale, NJ: Lawrence Erlbaum Associates. Conway, K. P., Swendsen, J. D., Rounsaville, B. J., & Merikangas, K. R. (2002). Personality, drug of choice, and comorbid psychopathology among substance abusers. Drug and Alcohol Dependence, 65, Davis, R. N. (1999). Web-based administration of a personality questionnaire: Comparison with traditional methods. Behavior Research Methods, Instruments & Computers, 31, Depue, R. A., & Lenzenweger, M. F. (2001). A neurobehavioral dimensional model. In W. J. Livesly (Ed.), Handbook of personality disorders: Theory, research, and treatment (pp ). New York, NY: Guilford Press. Dougherty, D. M., Bjork, J. M., Huckabee, H. C. G., Moeller, F. G., & Swann, A. C. (1999). Laboratory measures of aggression and impulsivity in women with borderline personality disorder. Psychiatry Research, 85,

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