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Is the Behavioural Inhibition System the core vulnerability for cluster C personality disorders?
Personality and Individual Differences 31 (2001) 349±359
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Is the Behavioural Inhibition System the core vulnerability for cluster C personality disorders? X. Caseras a,*, R. Torrubia a, J.M. Farre b a
Departament de Psiquiatria i Medicina Legal, Universitat AutoÁnoma de Barcelona, Edi®ci M, Campus de Bellaterra s/n, Barcelona, Catalonia, Spain b Servei de Medicina PsicosomaÁtica, Institut Universitari Dexeus, Barcelona, Catalonia, Spain Received 3 November 1999; received in revised form 15 June 2000; accepted 19 July 2000
Abstract The aim of the present study was to determine if Behavioural Inhibition System (BIS) functioning, as described by Gray (Gray, J.A.C. (1982). The Neuropsychology of anxiety: an enquiry into the functions of the Septo-Hippocampal system. Oxford: Oxford University Press), would be a core vulnerability for cluster C personality disorders (PD), that is, if these patients would show a higher anxiety trait (i.e. in Gray's terms) than patients with other PD or without Axis II disorders. A total sample of 77 out-patients was assessed with the Eysenck Personality Questionnaire, Sensitivity to Punishment and Sensitivity to Reward Scales, Karolinska Scales of Personality, and the Structured-Interview for DSM-III-R Personality Disorders (SCID-II). Analyses were conducted considering the following groups: presence of cluster C personality disorder/s, presence of clusters A/B personality disorder/s, absence of personality disorder (non-PD). As a second step, cluster C and non-PD groups were also subdivided according to the presence/absence of anxiety or aective Axis I symptoms. Overall, results showed higher scores on anxiety trait-related scales in the cluster C group. However, only Somatic Anxiety, Psychasthenia and Sensitivity to Punishment scales (SP) clearly distinguished cluster C from each one of the other two groups. After a second analysis, only the Sensitivity to Punishment scale showed independence from Axis I status while discriminating between cluster C and non-PD patients. Results were similar when only behavioural items from the SP scale were considered. From these results we can conclude that a higher BIS functioning would dierentiate cluster C personality disorders from patients with other PD or without PD, and that considering only the behavioural anxiety component in their assessment, a low Axis I in¯uence is obtained. # 2001 Elsevier Science Ltd. All rights reserved. Keywords: Anxiety; Personality disorders; Cluster C; Behavioural Inhibition System
* Corresponding author. Tel.: +34-93-5811223; fax: +34-93-5811435. E-mail address: [email protected] (X. Caseras). 0191-8869/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved. PII: S0191-8869(00)00141-0
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1. Introduction Since the publication of the third edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III; APA, 1980), the diagnosis of so-called personality disorders (PD) is considered on an Axis independent of other psychiatric syndromes. Anchored within medical tradition, the classi®cation of PD in the DSM takes the form of a categorial model. This approach implies that normal and abnormal personality are qualitatively dierent, and leads us to consider the existence of some type of genetic or biological factor which should enable us to distinguish between them (Strack & Lorr, 1997). This viewpoint has been widely criticised because of the many problems deriving from it, among which we would highlight the following: (1) the high co-occurence found between dierent diagnoses of PD according to the DSM (e.g. Widiger & Rogers, 1989, found in four studies an average percentage of patients with a multiple PD diagnosis of over 80%); (2) the high co-morbidity between Axis I and Axis II disorders, in some cases owing to the great similarity between the diagnostic criteria for the two types of disorder, making them practically undistinguishable [e.g. avoidant PD and generalised social phobia (Tyrer, Gunderson, Lyons & Tohen, 1997)]; and (3) validity problems in the diagnostic criteria for each PD (e.g. Blais & Norman, 1997, found major divergence and convergence criteria sets problems in the DSM-IV PD classi®cation). A dierent perspective has been adopted in psychometric personality research, where dimensional models have typically been used. From this viewpoint, personality may be described as the combination of diverse dimensions (the number of which will depend on the model considered), observable to a greater or lesser degree in all individuals. According to this perspective, what would determine the existence of a PD would be an extreme position on one of these dimensions (Strack & Lorr, 1997) or some speci®c combination of them (LoÂpez-Ibor, 1997). This being said, when it comes to a consideration of the existence of a PD, some authors feel it important to also take into account the presence of a clinically signi®cant functional deterioration (Widiger, 1994). Recently, dierent authors have defended the need for a dimensional approach to PD. According to them, this sort of focus might be more reliable and valid than the categorial perspective (Widiger, 1992). Among the dimensional models put forward to conceptualize PD, worthy of consideration are Costa and McCrae's (1992) Five Factors model, Cloninger's model contemplating four temperamental and three character dimensions (Cloninger, Svrakic & Przybeck, 1993), and that by Siever and Davis (1991) based on four dimensions related to dierent biological vulnerabilities associated with Axis I from the DSM. There are other dimensional personality models developed from basic animal research, which despite enjoying important experimental support, have not been used to conceptualize PD. They could be of special relevance to this task. A clear example is Gray's model (1982, 1987). Focusing on this last model, its author hypothesized the existence of a conceptual nervous system, the Behavioural Inhibition System (BIS), which would be activated in front of conditioned aversive stimuli (threatening), new stimuli, and cues indicating the non-appearance of positive reinforcement (frustrative non-reward), resulting in a behavioural stop (inhibition). The BIS would be a biological substrate of anxiety, and would explain the acquisition and maintenance of passive avoidance behaviours. Individual dierences in BIS functioning would correspond as regards personality with the anxiety dimension. The neurobiological bases of the BIS would
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include Papez's circuit, the septohippocampal system and the noradrenergic projections from the locus ceruleus and the serotoninergic projections from the raphe nuclei. Analogously to the BIS, Gray de®nes the Behavioural Activation System (BAS) which would be activated by conditioned reward stimuli and non-punishment cues, resulting in approach behaviours. Individual dierences in the activation of the BAS would correspond to the impulsivity dimension. Following on from this, it would seem logical to regard the functioning of the BIS as the core vulnerability for cluster C PD (characterized by high anxiety/fearfulness, according to the DSM). Thus, people with a high reactivity in this conceptual nervous system (high anxiety on the personality dimension) would display a greater vulnerabilty to suering disorders of this type. In this sense, the harm avoidance (HA) dimension proposed by Cloninger (1987, 1994) bears a great resemblance to the anxiety dimension as regards both psychobiological mechanisms and observable behaviours. The HA has been shown to be related to the presence of cluster C PD (Goldman, Skodol, McGrath & Oldham, 1994; Svarick, Whitehead, Przybeck & Cloninger, 1993). Several scales related to BIS functioning have been developed, being directly based on Gray's model (Ball & Zuckerman, 1990; Carver & White, 1994; Torrubia, AÁvila, Molto & Caseras, in press). From among them, the Sensitivity to Punishment (SP) scale has shown good psychometric properties (Torrubia et al., in press) and a good predictive and descriptive capacity in various laboratory studies. SP correlates positively with other anxiety trait scales such as the STAI (Spielberger, 1983), the HA and the Manifest Anxiety Scale (Taylor, 1953), whilst maintaining independence from the anxiety state on the STAI (Caseras & Torrubia, 1996; Balada, Torrubia & ArqueÂ, 1992, 1993). Con®rming Gray's hypotheses, the SP is related positively with Neuroticism (N) and negatively with Extraversion (E), both from the Eysenck Personality Questionnaire (EPQ; Eysenck & Eysenck, 1975). Similar results were obtained by Brebner and Martin (1995) and Zuckerman (1999) using an English translation of this scale. Also, as the theoretical model predicts, high scorers on SP have shown a greater facility for passive avoidance learning and a greater resistance to the extinction of such behaviours in laboratory tests, as well as a longer general reaction time (i.e. greater behavioural inhibition) in situations where punishment cues are present (for a review, see Torrubia, AÁvila, Molto & Grande, 1995). Other authors have used E and N scales from the EPQ to measure BIS functioning, given the theoretical relationship between the two models (i.e. anxiety should presumably range along the quadrants de®ned by E and N, from N+/E to N /E+). Finally, in other cases alternative psychometric instruments which enable a more detailed exploration of several anxiety-related traits have been preferred; along these lines, Stallings, Hewitt, Cloninger, Heath and Eaves (1996) used the Karolinska Scales of Personality (KSP; Klinteberg, Schalling & Magnusson, 1986) with good results. The aim of the present study was to determine if a more active BIS (evaluated by means of a scale speci®cally constructed for the purpose: SP) could be considered a factor of vulnerability to cluster C PD independently of the presence/absence of anxiety or aective Axis I symptoms. Prompted by the experience of other studies, anxiety trait was also measured using a combination of E and N, and KSP anxiety scales. Higher scores on this dimension, measured by the three procedures above, were expected in patients with this type of disorder in comparison with: (1) other PD patients; and (2) non-PD patients with Axis I pathologies, which included anxiety or aective symptoms.
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2. Method 2.1. Subjects and procedure A sample of 77 out-patients from the Psychiatry and Psychology Unit of a private clinic participated in the present study, of which 31 (40.3%) were males and 46 (59.7%) were females. All of them received psychological/psychiatric advice. Of the participants, 38 cases (49.4%) presented anxiety or aective symptoms (DSM-IV diagnosis of agoraphobia, panic attacks, speci®c phobia, dysthymic disorder), and 39 patients (50.6%) consulted for other reasons (sexual disfunctions, marriage problems, counselling) but did not present anxiety or aective symptoms. Axis I diagnoses were made following a psychiatric interview. Of the whole sample, 28 patients (36.4%) were diagnosed as having one or more PD (38.2% of them had more than one PD). There were 18 patients with one or more PD from cluster C only (64.3% from PD diagnoses) while 10 had one or more PD from clusters A and/or B (35.7% from PD diagnoses). The breakdown of the cluster C group was as follows: 88.9% obsessive-compulsive PD, 55.6% dependent PD, and 38.9% avoidant PD (the sum is not 100% because of co-occurrence between them). Cases with co-occurrence between cluster C and PD from the other clusters were not included in this study. In summary, the 77 subjects were divided into three PD groups: those with one or more cluster C PD (cluster C), those with one or more cluster A and/or B PD (A/B PD) and those without any PD (non-PD). As a second step, in order to study the in¯uence of anxiety or aective symptoms on scale scores, dierentiation was made in each PD group between patients with anxiety or aective Axis I symptoms and patients without these kind of symptoms. The subdivision of the A/B PD group resulted in groups too small to be considered and was therefore discarded. Thus, the groups ®nally considered in this second stage were: (1) cluster C plus Axis I anxiety or aective symptoms; (2) cluster C without these Axis I symptoms; (3) non-PD with anxiety or aective symptoms; and (4) non-PD and non Axis I symptoms. 2.2. Measures The Structured-Interview for DSM-III-R Personality Disorders (SCID-II; Spitzer, Williams, Gibbon & First, 1990) in a Spanish version (GoÂmez-Beneyto et al., 1994) was used to diagnose PD. As a measure of BIS functioning the Catalan version of the SPSR questionnaire was used (Torrubia et al., in press). This instrument was elaborated and validated directly based on Gray's model. The SPSR questionnaire includes two 24-item scales aimed to measure individual dierences in the anxiety dimension (SP) and individual dierences in impulsivity [Sensitivity to Reward (SR)] as de®ned by Gray. The items included on SP were designed to measure behavioural inhibition in general situations involving the possibility of aversive consequences or novelty and cognitive processes produced by the threat of punishment. Items from SR refer to situations in which people could do something to obtain rewards such as money, sexual partners, power and so on. The SPSR questionnaire has shown good reliability (internal and temporal) and validity indexes in dierent studies. We also used the KSP (Klinteberg et al., 1986) in a Spanish version. This includes, among others, dierent scales referring to cognitive and somatic anxiety components. Factorial analysis
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of KSP (Ortet & Torrubia, 1992) resulted in three factors. The ®rst grouped together scales related with the anxiety trait: Somatic Anxiety (SA), Muscular Tension (MT), Psychic Anxiety (PA), Psychasthenia (PT), Suspicion (SU), Guilt (GU), and Inhibition of Aggression (IA). The second factor brought together scales related with behavioural activation: Monotony Avoidance (MA), Impulsiveness (IM), Detachment (DT), Socialisation (SO), and Social Desirability (SD). Finally, the third included scales related with aggression: Irritability (IR), Verbal Aggression (VA), and Indirect Aggression (ID). Finally, considering the relationship between Eysenck's and Gray's models and the fact that a large number of studies in BIS functioning used E and N scales from the EPQ to assess anxiety and impulsivity, we also administered a Catalan version of the EPQ questionnaire (Eysenck, Garcia, Torrubia, AÁvila & Ortet, 1992). Subjects answered each questionnaire individually (including the screening questionnaire of SCID-II). The SCID-II interview was then immediately conducted only for PD categories that had been con®rmed on the screening questionnaire. 3. Results Correlations across all scales used in this study indicated a good convergence among anxiety dimension measures. All KSP-anxiety related scales (SA, MT, PA, PT, SU, GU, and IA) showed signi®cant and positive correlations among them and also with SP (the highest correlation with PA, r=0.80, P<0.001; and the lowest with SU, r=0.49, P<0.001). All these measures also showed signi®cant and positive correlations with N (the highest correlation with PA and SP, in both cases r=0.77, P<0.001; and the lowest with SU, r=0.44, P<0.001) and signi®cant and negative correlations with E (the highest correlation with SP, r= 0.57, P<0.001; and the lowest correlation with IA, r= 0.28, P<0.01). Our cluster C group was atypical because most patients had an obsessive-compulsive PD diagnosis. For this reason, we studied the homogeneity of scale scores within the cluster C group. The ®rst comparison was made between patients with a single obsessive-compulsive PD diagnosis and those with dependent and/or avoidant PD diagnoses. Because of the small number of cases Mann-Whitney U tests were performed. Only the SO scale from KSP showed dierences between these two groups (z=2.08, P<0.05), scores being higher for obsessive-compulsive than for avoidant or dependent patients. The second comparison was between patients with a single obsessivecompulsive PD diagnosis and those with obsessive-compulsive plus dependent and/or avoidant PD diagnoses. Using the above procedure, VA was the only scale that showed dierences (z=1.97, P=0.05), scores being higher for patients with a single obsessive-compulsive PD. From these results it can be assumed that no substantial dierences were present within cluster C patients. This homogeneity enabled us to work with the whole cluster C group. In accordance with our objective, comparisons among cluster C, clusters A/B and non-PD groups were performed using analysis of variance. When this was signi®cant, contrasts based on Students' t-test comparisons of group means were performed. Fig. 1 shows personality trait pro®les for each group. An asterisk indicates signi®cant dierences between the cluster C group and each one of the other two groups. Pro®les are presented in T scores, calculated using local norms for the general population. As can be seen, the cluster C group showed a higher pro®le on all
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Fig. 1. Personality traits pro®les in T scores for patients from the cluster C group, from the A/B PD group, and patients without PD (non-PD). Asterisk indicates signi®cant dierences on Students' t-test comparisons between the cluster C group and A/B PD and non-PD groups. SA, somatic anxiety; MT, muscular tension; PA, psychic anxiety; PT, psychathenia; GU, guilt; SU, suspicion; IA, inhibition of aggression; MA, monotony avoidance; IM, impulsiveness; SO, socialization; IR, irritability; VA, verbal aggression; ID, indirect aggression; DT, detachment; SD, social desirability; E, extraversion; N, neuroticism; P, psychoticism; L, lie; SP, sensitivity to punishment; SR, sensitivity to reward.
KSP scales related with anxiety (SA, MT, PA, PT, GU, SU, and IA). Scores on the ®rst four scales being almost one standard deviation above the mean. The cluster C pro®le was nearer to the A/B PD group than to the non-PD group pro®le. In contrast, on KSP scales related with behavioural activation (MA, IM, DT, SO, and SD), cluster C group scores were more similar to those of the non-PD group; in both groups, scores were near midpoint, except those of MA which were very low for non-PD and even lower for the cluster C group. The A/B PD group scored higher on behavioural activation scales, except for SO. Scores on aggression scales (IR, VA, and ID) were very similar between the three groups, and near the midpoint in all cases. No EPQ scale dierentiated between cluster C and each one of the other two groups. Although higher for cluster C, N scores were not statistically dierent between this and the A/B PD group. In the SPSR questionnaire, only SP dierentiated between the cluster C group (showing a score near one standard deviation above the mean) and each one of the other two groups. Signi®cant dierences between cluster C group and each one of the other two groups were only obtained for SA (cluster C vs. non-PD, t=4.64, P<0.001; cluster C vs. A/B PD, t=2.30, P<0.05), PT (cluster C vs. non-PD, t= 4.44, P<0.001; cluster C vs. A/B PD, t=2.52, P<0.05) and SP (cluster C vs. non-PD, t=5.24, P<0.001; cluster C vs. A/B PD, t= 3.00, P<0.01). Other signi®cant dierences on anxiety scales (ie. MT, PA, GU, SU, IA) were obtained between cluster C and the non-PD group, but these were not dierent when cluster C was compared with the A/B group. In accordance with our objective, we also compared scale scores across the four groups resulting from the consideration of Axis I symptoms (cluster C plus anxiety or aective symptoms, cluster C without these Axis I symptoms, non-PD with anxiety or aective symptoms, non-PD
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without these Axis I symptoms). As before, we used analysis of variance and Students' t-test comparisons between all possible pairs (Table 1). As we can see in Table 1, subjects in the cluster C plus anxiety or aective symptoms group got higher scores on most anxiety scales than the non-PD and non Axis I symptoms group. However, when comparison was made between the cluster C and non-PD groups both with Axis I symptoms, the former only got higher scores on SA, MT, PA, PT, N and SP. Most of these scales did not dierentiate between patients with only anxiety or aective Axis I symptoms and those with only a cluster C PD. If we assume a severity order across the four groups, the middle range was Table 1 Scale means and standard deviations dividing cluster C and non-PD groups into two categories (patients with Axis I anxiety or aective symptoms, and patients without these kind of symptoms)a Without PD
With cluster C PD
F
Order of groups
With Axis I Without Axis I With Axis I Without Axis I symptomatology (1) symptomatology (2) symptomatology (3) symptomatology (4) n=12 n=6 n=22 n=27 Mean (SD) Mean (SD) Mean (SD) Mean (SD) KSP SA MT PA PT GU SU IA MA IM DT SO IR VA ID SD
20.00 20.26 21.88 22.56 11.48 10.22 23.78 25.00 23.81 20.48 56.59 11.70 13.85 12.93 28.11
(4.62) (5.27) (4.66) (4.00) (1.63) (2.34) (3.82) (4.06) (2.84) (3.43) (6.89) (2.38) (2.83) (2.59) (4.20)
22.68 22.81 24.95 24.59 12.50 11.32 24.82 22.05 22.55 22.68 54.09 11.68 13.59 13.59 27.36
(5.57) (5.21) (4.97) (4.21) (1.97) (2.36) (2.95) (3.48) (3.31) (3.77) (7.42) (2.48) (2.50) (2.82) (4.01)
26.80 25.40 28.60 26.50 14.33 12.00 26.17 22.33 22.83 24.33 53.20 12.67 13.00 12.00 28.60
(4.92) (5.86) (1.52) (2.66) (2.16) (2.55) (2.64) (2.34) (3.37) (1.21) (7.79) (1.37) (1.41) (1.90) (2.70)
28.91 27.42 30.25 29.25 12.92 12.58 27.00 20.92 22.00 21.25 53.00 13.08 13.08 14.08 28.17
(5.89) (5.87) (4.90) (3.36) (3.12) (2.84) (5.49) (5.26) (3.52) (4.09) (8.77) (3.68) (2.39) (3.29) (2.44)
8.64** 5.29** 9.75** 8.68** 3.62* 2.88* 2.19 3.78* 1.15 2.77* 0.89 1.03 0.34 1.17 0.25
4 > 2,1 ; 3 > 1 4 > 1,2 4 > 1,2 ; 3,2 > 1 4 > 2,1 ; 3 > 1 3>1 3>1 4>1 1 > 2,4 n.s. dierences 3,2 > 1 n.s. dierences n.s. dierences n.s. dierences n.s. dierences n.s. dierences
EPQ E N P L
13.62 9.62 3.15 10.00
(4.39) (5.48) (1.76) (3.41)
12.38 12.05 3.52 10.24
(4.38) (6.05) (2.36) (3.75)
8.00 17.20 3.60 11.60
(2.35) (3.11) (1.82) (2.88)
10.42 17.58 3.08 12.08
(5.52) (4.06) (2.54) (3.58)
2.93* 7.54** 0.19 0.17
1 > 4,3 4,3 > 1 ; 4 > 2 n.s. dierences n.s. dierences
SPSR SP SP
7.26 (5.78) 8.11 (4.57)
10.27 (5.57) 6.77 (3.41)
17.20 (4.55) 9.40 (4.16)
17.00 (5.92) 10.00 (4.18)
10.52** 3,4 > 2,1 1.79 4>2
a One-way analysis of variance and dierences resulting after means comparisons using Students' t-test between possible pairs. SA, somatic anxiety; MT, muscular tension; PA, psychic anxiety; PT, psychasthenia; GU, guilt; SU, suspicion; IA, inhibition of aggression; MA, monotony avoidance; IM, impulsiveness; SO, socialization; IR, irritability; VA, verbal aggression, ID, indirect aggression; DT, detachment; SD, social desirability; E, extraversion; N, neuroticism; P, psychoticism; L, lie; SP, sensitivity to punishment; SR, sensitivity to reward. *P<0.05. **P<0.001.
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indistinguishable using most of these scales. Only the SP scale dierentiated between cluster C group and non-PD patients, independently of presence/absence of anxiety or aective symptoms. The scales with a majority of cognitive and somatic anxiety trait-based items failed to dierentiate patients from cluster C without anxiety or aective symptoms and patients from the nonPD group with these kind of symptoms. The SP scale, consisting mainly of behavioural anxiety items, did dierentiate between these two groups of patients. For this reason, the SP score was split into two scores: one the sum of items related to behavioural anxiety, and the other to cognitive anxiety. After this division, the results of the analysis of the behaviour anxiety score were the same as those obtained from the whole SP scale; that is, highly signi®cant analysis of variance [F (3, 62)=7.94; P<0.001] and t-test comparisons indicating dierences between the two PD groups (cluster C vs. non-PD) independently of the presence/absence of the Axis I anxiety or aective symptoms. In the case of the cognitive score, analysis of variance was signi®cant [F (3, 62)=11.59; P<0.001], but t-test comparisons resulted in no dierences between cluster C patients without anxiety or aective symptoms and non-PD patients with these kind of symptoms (the middle range groups in the aforementioned severity order). The order of groups was the same as that obtained for PA expressed in Table 1. 4. Discussion In the ®rst place, an examination of the correlation matrix reveals that the SP scale, the KSP anxiety scales previously cited, and the combination of E and N show signi®cant correlations between them in the direction anticipated. At the same time, we may accept that our group of cluster C patients displayed sucient homogeneity in their psychometric pro®le to be studied as a whole, without it being necessary to dierentiate between dependent, avoidant and obsessivecompulsive PD. Observing Fig. 1, the hypothesis of a greater anxiety trait in cluster C PD patients would seem to be con®rmed. This group of patients had higher scores on all the anxiety trait scales administered. In spite of this, most scores on these scales were only signi®cantly dierent between the cluster C and non-PD patient group, although they did not allow us to dierentiate between the former and the group of A/B PD patients. Only the PT, SA (both from KSP) and SP (from the SPSR) scales were signi®cantly dierent between the cluster C PD patients and other PD patients. Bearing in mind the content of these scales, it would appear that cluster C patients, in comparison with those with other PD, would display high scores on the behavioural, cognitive and somatic components of the anxiety trait. In any case, and according to our results, we may accept that a greater activity of the BIS measured by a scale speci®cally constructed for the purpose (i.e. SP), or non-speci®c parallel procedures, dierentiated cluster C patients from A/B PD and non-PD patients. In the present study, the SP scale proved to be independent of anxiety or aective state symptoms. However, the PT and SA scales, mostly based on cognitive and somatic components, respectively, did not allow a clear distinction between cluster C patients and those without this Axis II disorder but with anxiety or aective symptoms. This may be deduced from the results obtained when cluster C and non-PD groups were divided to consider the presence/absence of Axis I anxiety or aective symptoms. Also, after breaking down the SP scale score into a purely
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behavioural one (sum of the items related to avoidance behaviours) and the other a cognitive one (sum of the items related to worries), we observed that when only items related to passive avoidance behaviours were considered, the capacity for discrimination between patients without anxiety or aective symptoms from cluster C group and patients with these Axis I symptoms from the non-PD group was maintained; when the items related to worries were considered separately, however, this discriminatory capacity was lost. This might explain why the anxiety trait scales which include a higher proportion of items referring to cognitive and somatic components show a greater in¯uence on the psychopathological states [as happens with the HA (Svrakic, Przybeck & Cloninger, 1992; Starcevic, Uhlenhuth & Fallon, 1995; Battaglia, Przybeck, Bellodi & Cloninger, 1996)]. We may conclude that the de®ning and characteristic feature of cluster C patients with regard to other patients without this type of disorder, would be a behavioural style based on the predominance of passive avoidance behaviours. In relation to this, Fowles (1987) suggested that high anxiety trait individuals would not necessarily be those to suer most from anxiety states, as they would be more likely to avoid ``risk'' situations. In accordance with this hypothesis, and following on from what has been argued above, cluster C patients, owing to their avoidant behavioural style, would encounter a small number of aversive stimuli, resulting in less frequent experiences of anxiety, simply because of their greater tendency to passive avoidance. According to this, the treatment of cluster C patients should involve the modi®cation of their evasive behavioural style, so reducing their sensitivity to aversive stimuli, even when this might mean the greater temporary presence of an anxiety state. In conclusion, our results seem to suggest that cluster C patients are characterised, in comparison with A/B PD or non-PD patients, by a greater activity in the neurobiological structures related to the BIS. This dierence between cluster C patients and other patients can be detected using the SA, PT and SP scales, although the last is the only one to have proved independent of Axis I anxiety and aective symptoms. We therefore propose that, in psychiatric populations, SP may be considered a good psychometric measure of the activity of the BIS. It is certainly interesting that the SP scale which best discriminates between cluster C patients and non-PD patients, independently of Axis I symptoms, is the only one of those used directly constructed from the theoretical assumptions of Gray's model. Other scales evaluating this or similar constructs (e.g. the scales by Carver & White, 1994, the HA, etc.) should be considered in future research. Also, further research should aim to determine if a more active BIS would really be a core vulnerability for cluster C, as hypothesized in this study, or simply an indicator of its presence. In the ®rst case, getting a high score on a scale like SP (i.e. that has proved to be a measure of activity of this system) would not necessarily indicate the presence of a cluster C PD, meaning that a non-psychiatric population might also display the same personality pro®le. In these cases, it might be expected that other factors (i.e. environmental) had acted as safeguards against the development of an Axis II disorder. In the second case, it might ideally be expected that any cluster C PD should lead to a high SP (i.e. sensitivity 1) and a low one in the case of other PD or non-PD individuals (i.e. speci®city 1). Our results do not provide an answer to this question, though personal experience inclines us towards the ®rst of the options. Further research on this matter is currently being considered by our team. Explanatory models of personality underlying PD could guide research and development of pharmacological and behavioural treatments. In the case of cluster C, the anxiety dimension from
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Gray's model could be a good starting point to work on this kind of PD from a dimensional viewpoint. Obviously, more research on this subject is needed, especially if we consider that our results could be in¯uenced by the atypically large presence of obsessive-compulsive PD in our sample. References APA. (1980). Diagnostic and statistical manual of mental disorders (3rd ed.). Washington, DC: American Psychiatric Association. Balada, F., Torrubia, R., & ArqueÂ, J. M. (1992). Thyroid hormone correlates of sensation seeking and anxiety in healthy human females. Neuropsychobiology, 25, 208±213. Balada, F., Torrubia, R., & ArqueÂ, J. M. (1993). Gonadal hormone correlates of sensation seeking and anxiety in healthy human females. Neuropsychobiology, 27, 91±96. Ball, S. A., & Zuckerman, M. (1990). Sensation Seeking, Eysenck's personality dimensions and reinforcement sensitivity in concept formation. Personality and Individual Dierences, 11, 343±353. Battaglia, M., Przybeck, T. R., Bellodi, L., & Cloninger, C. R. (1996). Temperament dimensions explain the comorbidity of psychiatric disorders. Comprehensive Psychiatry, 37, 292±298. Blais, M., & Norman, D. (1997). A psychometric evaluation of the DSM-IV personality disorders criteria. Journal of Personality Disorders, 11, 168±176. Brebner, M., & Martin, M. (1995). Testing for stress and happiness: the role of Personality Factors. In C. D. Spielberger, I. G. Sarason, J. Brebner, E. Greenglass, P. Laungani, & A. M. O'Roark, Stress and emotion. Anxiety, anger and curiosity (Vol. 15, pp. 139±172). Washington, DC: Taylor & Francis. Carver, Ch. S., & White, T. L. (1994). Behavioral Inhibition, Behavioral activation, and Aective Responses to impending reward and punishment: the BIS/BAS Scales. Journal of Personality and Social Psychology, 67, 319± 333. Caseras, X., & Torrubia, R. (1996, June). Vers un model descriptiu dels trets temperamentals rellevants en la inhibicioÂdesinhibicio conductual. [Looking for a descriptive model of the relevant personality traits on behavioral inhibition and disinhibition]. Paper presented at the meeting of the Catalan Society of Behavioral Research and Treatment (SCRITC), Bellaterra, Barcelona. Cloninger, C. R. (1987). A systematic method for clinical description and classi®cation of personality variants. Archives of General Psychiatry, 44, 573±588. Cloninger, C. R. (1994). Temperament and Personality. Current Opinion on Neurobiology, 4, 266±273. Cloninger, C. R., Svrakic, D. M., & Przybeck, T. R. (1993). A psychobiological model of temperament and character. Archives of General Psychiatry, 50, 975±990. Costa, P. T., & McCrae, R. R. (1992). The ®ve-factor model of personality and its relevance to personality disorders. Journal of Personality Disorders, 6, 343±359. Eysenck, H. J., & Eysenck, S. B. G. (1975). Manual of the Eysenck Personality Questionnaire. London: Hodder and Stoughton. Eysenck, S. B. G., Garcia, L., Torrubia, R., AÁvila, C., & Ortet, G. (1992). Versio catalana de l'EPQ per a adults: un instrument per la mesura de la personalitat. Annals de Medicina, 9, 223±230. Fowles, D. C. (1987). Application of a behavioral theory of motivation to the concepts of anxiety and impulsivity. Journal of Research in Personality, 21, 417±435. Goldman, R. G., Skodol, A. E., McGrath, P. J., & Oldham, J. M. (1994). Relationship between the Tridimensional Personality Questionnaire and DSM-III-R personality traits. American Journal of Psychiatry, 2, 274±276. GoÂmez-Beneyto, M., Villar, M., Renovell, M., PeÂrez, F., HernaÂndez, M., Leal, C., Cuquerella, M., Slok, C., & Asencio, A. (1994). The diagnosis of Personality Disorders with a modi®ed version of the SCID-II in a Spanish sample. Journal of Personality Disorders, 8, 104±110. Gray, J. A. (1982). The Neuropsychology of anxiety: an enquiry into the functions of the Septo-Hippocampal System. Oxford: Oxford University Press. Gray, J. A. (1987). The psychology of fear and stress. Cambridge: Cambridge University Press.
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Klinteberg, B., Schalling, D., & Magnusson, D. (1986). Individual development and adjustment. Self-Reported assessment of personality traits, 64. Stockholm: University of Stockholm. LoÂpez-Ibor, J. J. (1997). The Concept and Boundaries of Personality Disorders. American Journal of Psychiatry, 154(Festschrift Supplement), 21±25. Ortet, G., & Torrubia, R. (1992, June). Spanish language version of the Karolinska Scales of Personality (KSP): First data. Paper presented at the Sixth European Association for Personality Psychology Conference, Groningen, The Netherlands. Siever, L. J., & Davis, K. L. (1991). A psychobiological perspective on the personality disorders. American Journal of Psychiatry, 148, 1647-1.658. Spielberger, C. D. (1983). Manual for the State-Trait Anxiety Inventory (Form Y). Palo Alto: Consulting Psychologist Press. Spitzer, R. L., Williams, J. B. W., Gibbon, M., & First, M. B. (1990). Structured clinical interview for DSM-III-R (SCID-II). Washington, DC: American Psychiatric Press. Stallings, M. C., Hewitt, J. K., Cloninger, C. R., Heath, A. C., & Eaves, L. J. (1996). Genetic and environmental structure of the Tridimensional Personality Questionnaire: three or four temperament dimensions? Journal of Personality and Social Psichology, 70, 127±140. Starcevic, V., Uhlenhuth, E. H., & Fallon, S. (1995). The Tridimensional Personality Questionnaire as an instrument for screening personality disorders: use in patients with generalized anxiety disorder. Journal of Personality Disorders, 9, 247±253. Strack, S., & Lorr, M. (1997). Invited essay: the challenge of dierentiating normal and disordered personality. Journal of Personality Disorders, 11, 105±122. Svrakic, D. M., Przybeck, T. R., & Cloninger, C. R. (1992). Mood states and personality traits. Journal of Aective Disorders, 24, 217±226. Svrakic, D. M., Whitehead, C., Przybeck, T. R., & Cloninger, C. R. (1993). Dierential diagnosis of Personality Disorders by the Seven-Factor model of temperament and character. Archives of General Psychiatry, 50, 991±999. Taylor, J. A. (1953). A personality scale of manifest anxiety. Journal of Abnormal and Social Psychology, 48, 285±290. Torrubia, R., AÁvila, C., MoltoÂ, J., & Caseras, X. (in press). The Sensitivity to Punishment and Sensitivity to Reward Questionnaire (SPSRQ) as a measure of Gray's Anxiety and Impulsivity dimensions. Personality and Individual Dierences. Torrubia, R., AÁvila, C., MoltoÂ, J., & Grande, I. (1995). Testing for stress and happiness: the role of the Behavioral Inhibition System. In C. D. Spielberger, I. G. Sarason, J. Brebner, E. Greenglass, P. Laungani, & A. M. O'Roark, Stress and emotion. Anxiety, anger and curiosity (Vol. 15, pp. 189±208). Washington, DC: Taylor & Francis. Tyrer, P., Gunderson, J., Lyons, M., & Tohen, M. (1997). Special feature: extent of comorbidity between mental state and personality disorders. Journal of Personality Disorders, 11, 242±259. Widiger, T. A. (1992). Categorical versus Dimensional classi®cation: implications from and for research. Journal of Personality Disorders, 6, 287±300. Widiger, T. A. (1994). Conceptualizating a disorder of personality from the Five-Factor model. In P. T. Costa, & T. A. Widiger, Personality Disorders and the Five-Factors model of Personality (pp. 311±317). Washington: American Psychological Association. Widiger, T. A., & Rogers, J. H. (1989). Prevalence and comorbidity of personality disorders. Psychiatric Annals, 19, 132±136. Zuckerman, M. (1999). Incentive motivation: just extraversion? Behavioral and Brain Sciences, 22, 539±540.
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Is the Behavioural Inhibition System the core vulnerability for cluster C personality disorders? X. Caseras a,*, R. Torrubia a, J.M. Farre b a
Departament de Psiquiatria i Medicina Legal, Universitat AutoÁnoma de Barcelona, Edi®ci M, Campus de Bellaterra s/n, Barcelona, Catalonia, Spain b Servei de Medicina PsicosomaÁtica, Institut Universitari Dexeus, Barcelona, Catalonia, Spain Received 3 November 1999; received in revised form 15 June 2000; accepted 19 July 2000
Abstract The aim of the present study was to determine if Behavioural Inhibition System (BIS) functioning, as described by Gray (Gray, J.A.C. (1982). The Neuropsychology of anxiety: an enquiry into the functions of the Septo-Hippocampal system. Oxford: Oxford University Press), would be a core vulnerability for cluster C personality disorders (PD), that is, if these patients would show a higher anxiety trait (i.e. in Gray's terms) than patients with other PD or without Axis II disorders. A total sample of 77 out-patients was assessed with the Eysenck Personality Questionnaire, Sensitivity to Punishment and Sensitivity to Reward Scales, Karolinska Scales of Personality, and the Structured-Interview for DSM-III-R Personality Disorders (SCID-II). Analyses were conducted considering the following groups: presence of cluster C personality disorder/s, presence of clusters A/B personality disorder/s, absence of personality disorder (non-PD). As a second step, cluster C and non-PD groups were also subdivided according to the presence/absence of anxiety or aective Axis I symptoms. Overall, results showed higher scores on anxiety trait-related scales in the cluster C group. However, only Somatic Anxiety, Psychasthenia and Sensitivity to Punishment scales (SP) clearly distinguished cluster C from each one of the other two groups. After a second analysis, only the Sensitivity to Punishment scale showed independence from Axis I status while discriminating between cluster C and non-PD patients. Results were similar when only behavioural items from the SP scale were considered. From these results we can conclude that a higher BIS functioning would dierentiate cluster C personality disorders from patients with other PD or without PD, and that considering only the behavioural anxiety component in their assessment, a low Axis I in¯uence is obtained. # 2001 Elsevier Science Ltd. All rights reserved. Keywords: Anxiety; Personality disorders; Cluster C; Behavioural Inhibition System
* Corresponding author. Tel.: +34-93-5811223; fax: +34-93-5811435. E-mail address: [email protected] (X. Caseras). 0191-8869/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved. PII: S0191-8869(00)00141-0
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1. Introduction Since the publication of the third edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-III; APA, 1980), the diagnosis of so-called personality disorders (PD) is considered on an Axis independent of other psychiatric syndromes. Anchored within medical tradition, the classi®cation of PD in the DSM takes the form of a categorial model. This approach implies that normal and abnormal personality are qualitatively dierent, and leads us to consider the existence of some type of genetic or biological factor which should enable us to distinguish between them (Strack & Lorr, 1997). This viewpoint has been widely criticised because of the many problems deriving from it, among which we would highlight the following: (1) the high co-occurence found between dierent diagnoses of PD according to the DSM (e.g. Widiger & Rogers, 1989, found in four studies an average percentage of patients with a multiple PD diagnosis of over 80%); (2) the high co-morbidity between Axis I and Axis II disorders, in some cases owing to the great similarity between the diagnostic criteria for the two types of disorder, making them practically undistinguishable [e.g. avoidant PD and generalised social phobia (Tyrer, Gunderson, Lyons & Tohen, 1997)]; and (3) validity problems in the diagnostic criteria for each PD (e.g. Blais & Norman, 1997, found major divergence and convergence criteria sets problems in the DSM-IV PD classi®cation). A dierent perspective has been adopted in psychometric personality research, where dimensional models have typically been used. From this viewpoint, personality may be described as the combination of diverse dimensions (the number of which will depend on the model considered), observable to a greater or lesser degree in all individuals. According to this perspective, what would determine the existence of a PD would be an extreme position on one of these dimensions (Strack & Lorr, 1997) or some speci®c combination of them (LoÂpez-Ibor, 1997). This being said, when it comes to a consideration of the existence of a PD, some authors feel it important to also take into account the presence of a clinically signi®cant functional deterioration (Widiger, 1994). Recently, dierent authors have defended the need for a dimensional approach to PD. According to them, this sort of focus might be more reliable and valid than the categorial perspective (Widiger, 1992). Among the dimensional models put forward to conceptualize PD, worthy of consideration are Costa and McCrae's (1992) Five Factors model, Cloninger's model contemplating four temperamental and three character dimensions (Cloninger, Svrakic & Przybeck, 1993), and that by Siever and Davis (1991) based on four dimensions related to dierent biological vulnerabilities associated with Axis I from the DSM. There are other dimensional personality models developed from basic animal research, which despite enjoying important experimental support, have not been used to conceptualize PD. They could be of special relevance to this task. A clear example is Gray's model (1982, 1987). Focusing on this last model, its author hypothesized the existence of a conceptual nervous system, the Behavioural Inhibition System (BIS), which would be activated in front of conditioned aversive stimuli (threatening), new stimuli, and cues indicating the non-appearance of positive reinforcement (frustrative non-reward), resulting in a behavioural stop (inhibition). The BIS would be a biological substrate of anxiety, and would explain the acquisition and maintenance of passive avoidance behaviours. Individual dierences in BIS functioning would correspond as regards personality with the anxiety dimension. The neurobiological bases of the BIS would
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include Papez's circuit, the septohippocampal system and the noradrenergic projections from the locus ceruleus and the serotoninergic projections from the raphe nuclei. Analogously to the BIS, Gray de®nes the Behavioural Activation System (BAS) which would be activated by conditioned reward stimuli and non-punishment cues, resulting in approach behaviours. Individual dierences in the activation of the BAS would correspond to the impulsivity dimension. Following on from this, it would seem logical to regard the functioning of the BIS as the core vulnerability for cluster C PD (characterized by high anxiety/fearfulness, according to the DSM). Thus, people with a high reactivity in this conceptual nervous system (high anxiety on the personality dimension) would display a greater vulnerabilty to suering disorders of this type. In this sense, the harm avoidance (HA) dimension proposed by Cloninger (1987, 1994) bears a great resemblance to the anxiety dimension as regards both psychobiological mechanisms and observable behaviours. The HA has been shown to be related to the presence of cluster C PD (Goldman, Skodol, McGrath & Oldham, 1994; Svarick, Whitehead, Przybeck & Cloninger, 1993). Several scales related to BIS functioning have been developed, being directly based on Gray's model (Ball & Zuckerman, 1990; Carver & White, 1994; Torrubia, AÁvila, Molto & Caseras, in press). From among them, the Sensitivity to Punishment (SP) scale has shown good psychometric properties (Torrubia et al., in press) and a good predictive and descriptive capacity in various laboratory studies. SP correlates positively with other anxiety trait scales such as the STAI (Spielberger, 1983), the HA and the Manifest Anxiety Scale (Taylor, 1953), whilst maintaining independence from the anxiety state on the STAI (Caseras & Torrubia, 1996; Balada, Torrubia & ArqueÂ, 1992, 1993). Con®rming Gray's hypotheses, the SP is related positively with Neuroticism (N) and negatively with Extraversion (E), both from the Eysenck Personality Questionnaire (EPQ; Eysenck & Eysenck, 1975). Similar results were obtained by Brebner and Martin (1995) and Zuckerman (1999) using an English translation of this scale. Also, as the theoretical model predicts, high scorers on SP have shown a greater facility for passive avoidance learning and a greater resistance to the extinction of such behaviours in laboratory tests, as well as a longer general reaction time (i.e. greater behavioural inhibition) in situations where punishment cues are present (for a review, see Torrubia, AÁvila, Molto & Grande, 1995). Other authors have used E and N scales from the EPQ to measure BIS functioning, given the theoretical relationship between the two models (i.e. anxiety should presumably range along the quadrants de®ned by E and N, from N+/E to N /E+). Finally, in other cases alternative psychometric instruments which enable a more detailed exploration of several anxiety-related traits have been preferred; along these lines, Stallings, Hewitt, Cloninger, Heath and Eaves (1996) used the Karolinska Scales of Personality (KSP; Klinteberg, Schalling & Magnusson, 1986) with good results. The aim of the present study was to determine if a more active BIS (evaluated by means of a scale speci®cally constructed for the purpose: SP) could be considered a factor of vulnerability to cluster C PD independently of the presence/absence of anxiety or aective Axis I symptoms. Prompted by the experience of other studies, anxiety trait was also measured using a combination of E and N, and KSP anxiety scales. Higher scores on this dimension, measured by the three procedures above, were expected in patients with this type of disorder in comparison with: (1) other PD patients; and (2) non-PD patients with Axis I pathologies, which included anxiety or aective symptoms.
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2. Method 2.1. Subjects and procedure A sample of 77 out-patients from the Psychiatry and Psychology Unit of a private clinic participated in the present study, of which 31 (40.3%) were males and 46 (59.7%) were females. All of them received psychological/psychiatric advice. Of the participants, 38 cases (49.4%) presented anxiety or aective symptoms (DSM-IV diagnosis of agoraphobia, panic attacks, speci®c phobia, dysthymic disorder), and 39 patients (50.6%) consulted for other reasons (sexual disfunctions, marriage problems, counselling) but did not present anxiety or aective symptoms. Axis I diagnoses were made following a psychiatric interview. Of the whole sample, 28 patients (36.4%) were diagnosed as having one or more PD (38.2% of them had more than one PD). There were 18 patients with one or more PD from cluster C only (64.3% from PD diagnoses) while 10 had one or more PD from clusters A and/or B (35.7% from PD diagnoses). The breakdown of the cluster C group was as follows: 88.9% obsessive-compulsive PD, 55.6% dependent PD, and 38.9% avoidant PD (the sum is not 100% because of co-occurrence between them). Cases with co-occurrence between cluster C and PD from the other clusters were not included in this study. In summary, the 77 subjects were divided into three PD groups: those with one or more cluster C PD (cluster C), those with one or more cluster A and/or B PD (A/B PD) and those without any PD (non-PD). As a second step, in order to study the in¯uence of anxiety or aective symptoms on scale scores, dierentiation was made in each PD group between patients with anxiety or aective Axis I symptoms and patients without these kind of symptoms. The subdivision of the A/B PD group resulted in groups too small to be considered and was therefore discarded. Thus, the groups ®nally considered in this second stage were: (1) cluster C plus Axis I anxiety or aective symptoms; (2) cluster C without these Axis I symptoms; (3) non-PD with anxiety or aective symptoms; and (4) non-PD and non Axis I symptoms. 2.2. Measures The Structured-Interview for DSM-III-R Personality Disorders (SCID-II; Spitzer, Williams, Gibbon & First, 1990) in a Spanish version (GoÂmez-Beneyto et al., 1994) was used to diagnose PD. As a measure of BIS functioning the Catalan version of the SPSR questionnaire was used (Torrubia et al., in press). This instrument was elaborated and validated directly based on Gray's model. The SPSR questionnaire includes two 24-item scales aimed to measure individual dierences in the anxiety dimension (SP) and individual dierences in impulsivity [Sensitivity to Reward (SR)] as de®ned by Gray. The items included on SP were designed to measure behavioural inhibition in general situations involving the possibility of aversive consequences or novelty and cognitive processes produced by the threat of punishment. Items from SR refer to situations in which people could do something to obtain rewards such as money, sexual partners, power and so on. The SPSR questionnaire has shown good reliability (internal and temporal) and validity indexes in dierent studies. We also used the KSP (Klinteberg et al., 1986) in a Spanish version. This includes, among others, dierent scales referring to cognitive and somatic anxiety components. Factorial analysis
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of KSP (Ortet & Torrubia, 1992) resulted in three factors. The ®rst grouped together scales related with the anxiety trait: Somatic Anxiety (SA), Muscular Tension (MT), Psychic Anxiety (PA), Psychasthenia (PT), Suspicion (SU), Guilt (GU), and Inhibition of Aggression (IA). The second factor brought together scales related with behavioural activation: Monotony Avoidance (MA), Impulsiveness (IM), Detachment (DT), Socialisation (SO), and Social Desirability (SD). Finally, the third included scales related with aggression: Irritability (IR), Verbal Aggression (VA), and Indirect Aggression (ID). Finally, considering the relationship between Eysenck's and Gray's models and the fact that a large number of studies in BIS functioning used E and N scales from the EPQ to assess anxiety and impulsivity, we also administered a Catalan version of the EPQ questionnaire (Eysenck, Garcia, Torrubia, AÁvila & Ortet, 1992). Subjects answered each questionnaire individually (including the screening questionnaire of SCID-II). The SCID-II interview was then immediately conducted only for PD categories that had been con®rmed on the screening questionnaire. 3. Results Correlations across all scales used in this study indicated a good convergence among anxiety dimension measures. All KSP-anxiety related scales (SA, MT, PA, PT, SU, GU, and IA) showed signi®cant and positive correlations among them and also with SP (the highest correlation with PA, r=0.80, P<0.001; and the lowest with SU, r=0.49, P<0.001). All these measures also showed signi®cant and positive correlations with N (the highest correlation with PA and SP, in both cases r=0.77, P<0.001; and the lowest with SU, r=0.44, P<0.001) and signi®cant and negative correlations with E (the highest correlation with SP, r= 0.57, P<0.001; and the lowest correlation with IA, r= 0.28, P<0.01). Our cluster C group was atypical because most patients had an obsessive-compulsive PD diagnosis. For this reason, we studied the homogeneity of scale scores within the cluster C group. The ®rst comparison was made between patients with a single obsessive-compulsive PD diagnosis and those with dependent and/or avoidant PD diagnoses. Because of the small number of cases Mann-Whitney U tests were performed. Only the SO scale from KSP showed dierences between these two groups (z=2.08, P<0.05), scores being higher for obsessive-compulsive than for avoidant or dependent patients. The second comparison was between patients with a single obsessivecompulsive PD diagnosis and those with obsessive-compulsive plus dependent and/or avoidant PD diagnoses. Using the above procedure, VA was the only scale that showed dierences (z=1.97, P=0.05), scores being higher for patients with a single obsessive-compulsive PD. From these results it can be assumed that no substantial dierences were present within cluster C patients. This homogeneity enabled us to work with the whole cluster C group. In accordance with our objective, comparisons among cluster C, clusters A/B and non-PD groups were performed using analysis of variance. When this was signi®cant, contrasts based on Students' t-test comparisons of group means were performed. Fig. 1 shows personality trait pro®les for each group. An asterisk indicates signi®cant dierences between the cluster C group and each one of the other two groups. Pro®les are presented in T scores, calculated using local norms for the general population. As can be seen, the cluster C group showed a higher pro®le on all
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Fig. 1. Personality traits pro®les in T scores for patients from the cluster C group, from the A/B PD group, and patients without PD (non-PD). Asterisk indicates signi®cant dierences on Students' t-test comparisons between the cluster C group and A/B PD and non-PD groups. SA, somatic anxiety; MT, muscular tension; PA, psychic anxiety; PT, psychathenia; GU, guilt; SU, suspicion; IA, inhibition of aggression; MA, monotony avoidance; IM, impulsiveness; SO, socialization; IR, irritability; VA, verbal aggression; ID, indirect aggression; DT, detachment; SD, social desirability; E, extraversion; N, neuroticism; P, psychoticism; L, lie; SP, sensitivity to punishment; SR, sensitivity to reward.
KSP scales related with anxiety (SA, MT, PA, PT, GU, SU, and IA). Scores on the ®rst four scales being almost one standard deviation above the mean. The cluster C pro®le was nearer to the A/B PD group than to the non-PD group pro®le. In contrast, on KSP scales related with behavioural activation (MA, IM, DT, SO, and SD), cluster C group scores were more similar to those of the non-PD group; in both groups, scores were near midpoint, except those of MA which were very low for non-PD and even lower for the cluster C group. The A/B PD group scored higher on behavioural activation scales, except for SO. Scores on aggression scales (IR, VA, and ID) were very similar between the three groups, and near the midpoint in all cases. No EPQ scale dierentiated between cluster C and each one of the other two groups. Although higher for cluster C, N scores were not statistically dierent between this and the A/B PD group. In the SPSR questionnaire, only SP dierentiated between the cluster C group (showing a score near one standard deviation above the mean) and each one of the other two groups. Signi®cant dierences between cluster C group and each one of the other two groups were only obtained for SA (cluster C vs. non-PD, t=4.64, P<0.001; cluster C vs. A/B PD, t=2.30, P<0.05), PT (cluster C vs. non-PD, t= 4.44, P<0.001; cluster C vs. A/B PD, t=2.52, P<0.05) and SP (cluster C vs. non-PD, t=5.24, P<0.001; cluster C vs. A/B PD, t= 3.00, P<0.01). Other signi®cant dierences on anxiety scales (ie. MT, PA, GU, SU, IA) were obtained between cluster C and the non-PD group, but these were not dierent when cluster C was compared with the A/B group. In accordance with our objective, we also compared scale scores across the four groups resulting from the consideration of Axis I symptoms (cluster C plus anxiety or aective symptoms, cluster C without these Axis I symptoms, non-PD with anxiety or aective symptoms, non-PD
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without these Axis I symptoms). As before, we used analysis of variance and Students' t-test comparisons between all possible pairs (Table 1). As we can see in Table 1, subjects in the cluster C plus anxiety or aective symptoms group got higher scores on most anxiety scales than the non-PD and non Axis I symptoms group. However, when comparison was made between the cluster C and non-PD groups both with Axis I symptoms, the former only got higher scores on SA, MT, PA, PT, N and SP. Most of these scales did not dierentiate between patients with only anxiety or aective Axis I symptoms and those with only a cluster C PD. If we assume a severity order across the four groups, the middle range was Table 1 Scale means and standard deviations dividing cluster C and non-PD groups into two categories (patients with Axis I anxiety or aective symptoms, and patients without these kind of symptoms)a Without PD
With cluster C PD
F
Order of groups
With Axis I Without Axis I With Axis I Without Axis I symptomatology (1) symptomatology (2) symptomatology (3) symptomatology (4) n=12 n=6 n=22 n=27 Mean (SD) Mean (SD) Mean (SD) Mean (SD) KSP SA MT PA PT GU SU IA MA IM DT SO IR VA ID SD
20.00 20.26 21.88 22.56 11.48 10.22 23.78 25.00 23.81 20.48 56.59 11.70 13.85 12.93 28.11
(4.62) (5.27) (4.66) (4.00) (1.63) (2.34) (3.82) (4.06) (2.84) (3.43) (6.89) (2.38) (2.83) (2.59) (4.20)
22.68 22.81 24.95 24.59 12.50 11.32 24.82 22.05 22.55 22.68 54.09 11.68 13.59 13.59 27.36
(5.57) (5.21) (4.97) (4.21) (1.97) (2.36) (2.95) (3.48) (3.31) (3.77) (7.42) (2.48) (2.50) (2.82) (4.01)
26.80 25.40 28.60 26.50 14.33 12.00 26.17 22.33 22.83 24.33 53.20 12.67 13.00 12.00 28.60
(4.92) (5.86) (1.52) (2.66) (2.16) (2.55) (2.64) (2.34) (3.37) (1.21) (7.79) (1.37) (1.41) (1.90) (2.70)
28.91 27.42 30.25 29.25 12.92 12.58 27.00 20.92 22.00 21.25 53.00 13.08 13.08 14.08 28.17
(5.89) (5.87) (4.90) (3.36) (3.12) (2.84) (5.49) (5.26) (3.52) (4.09) (8.77) (3.68) (2.39) (3.29) (2.44)
8.64** 5.29** 9.75** 8.68** 3.62* 2.88* 2.19 3.78* 1.15 2.77* 0.89 1.03 0.34 1.17 0.25
4 > 2,1 ; 3 > 1 4 > 1,2 4 > 1,2 ; 3,2 > 1 4 > 2,1 ; 3 > 1 3>1 3>1 4>1 1 > 2,4 n.s. dierences 3,2 > 1 n.s. dierences n.s. dierences n.s. dierences n.s. dierences n.s. dierences
EPQ E N P L
13.62 9.62 3.15 10.00
(4.39) (5.48) (1.76) (3.41)
12.38 12.05 3.52 10.24
(4.38) (6.05) (2.36) (3.75)
8.00 17.20 3.60 11.60
(2.35) (3.11) (1.82) (2.88)
10.42 17.58 3.08 12.08
(5.52) (4.06) (2.54) (3.58)
2.93* 7.54** 0.19 0.17
1 > 4,3 4,3 > 1 ; 4 > 2 n.s. dierences n.s. dierences
SPSR SP SP
7.26 (5.78) 8.11 (4.57)
10.27 (5.57) 6.77 (3.41)
17.20 (4.55) 9.40 (4.16)
17.00 (5.92) 10.00 (4.18)
10.52** 3,4 > 2,1 1.79 4>2
a One-way analysis of variance and dierences resulting after means comparisons using Students' t-test between possible pairs. SA, somatic anxiety; MT, muscular tension; PA, psychic anxiety; PT, psychasthenia; GU, guilt; SU, suspicion; IA, inhibition of aggression; MA, monotony avoidance; IM, impulsiveness; SO, socialization; IR, irritability; VA, verbal aggression, ID, indirect aggression; DT, detachment; SD, social desirability; E, extraversion; N, neuroticism; P, psychoticism; L, lie; SP, sensitivity to punishment; SR, sensitivity to reward. *P<0.05. **P<0.001.
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indistinguishable using most of these scales. Only the SP scale dierentiated between cluster C group and non-PD patients, independently of presence/absence of anxiety or aective symptoms. The scales with a majority of cognitive and somatic anxiety trait-based items failed to dierentiate patients from cluster C without anxiety or aective symptoms and patients from the nonPD group with these kind of symptoms. The SP scale, consisting mainly of behavioural anxiety items, did dierentiate between these two groups of patients. For this reason, the SP score was split into two scores: one the sum of items related to behavioural anxiety, and the other to cognitive anxiety. After this division, the results of the analysis of the behaviour anxiety score were the same as those obtained from the whole SP scale; that is, highly signi®cant analysis of variance [F (3, 62)=7.94; P<0.001] and t-test comparisons indicating dierences between the two PD groups (cluster C vs. non-PD) independently of the presence/absence of the Axis I anxiety or aective symptoms. In the case of the cognitive score, analysis of variance was signi®cant [F (3, 62)=11.59; P<0.001], but t-test comparisons resulted in no dierences between cluster C patients without anxiety or aective symptoms and non-PD patients with these kind of symptoms (the middle range groups in the aforementioned severity order). The order of groups was the same as that obtained for PA expressed in Table 1. 4. Discussion In the ®rst place, an examination of the correlation matrix reveals that the SP scale, the KSP anxiety scales previously cited, and the combination of E and N show signi®cant correlations between them in the direction anticipated. At the same time, we may accept that our group of cluster C patients displayed sucient homogeneity in their psychometric pro®le to be studied as a whole, without it being necessary to dierentiate between dependent, avoidant and obsessivecompulsive PD. Observing Fig. 1, the hypothesis of a greater anxiety trait in cluster C PD patients would seem to be con®rmed. This group of patients had higher scores on all the anxiety trait scales administered. In spite of this, most scores on these scales were only signi®cantly dierent between the cluster C and non-PD patient group, although they did not allow us to dierentiate between the former and the group of A/B PD patients. Only the PT, SA (both from KSP) and SP (from the SPSR) scales were signi®cantly dierent between the cluster C PD patients and other PD patients. Bearing in mind the content of these scales, it would appear that cluster C patients, in comparison with those with other PD, would display high scores on the behavioural, cognitive and somatic components of the anxiety trait. In any case, and according to our results, we may accept that a greater activity of the BIS measured by a scale speci®cally constructed for the purpose (i.e. SP), or non-speci®c parallel procedures, dierentiated cluster C patients from A/B PD and non-PD patients. In the present study, the SP scale proved to be independent of anxiety or aective state symptoms. However, the PT and SA scales, mostly based on cognitive and somatic components, respectively, did not allow a clear distinction between cluster C patients and those without this Axis II disorder but with anxiety or aective symptoms. This may be deduced from the results obtained when cluster C and non-PD groups were divided to consider the presence/absence of Axis I anxiety or aective symptoms. Also, after breaking down the SP scale score into a purely
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behavioural one (sum of the items related to avoidance behaviours) and the other a cognitive one (sum of the items related to worries), we observed that when only items related to passive avoidance behaviours were considered, the capacity for discrimination between patients without anxiety or aective symptoms from cluster C group and patients with these Axis I symptoms from the non-PD group was maintained; when the items related to worries were considered separately, however, this discriminatory capacity was lost. This might explain why the anxiety trait scales which include a higher proportion of items referring to cognitive and somatic components show a greater in¯uence on the psychopathological states [as happens with the HA (Svrakic, Przybeck & Cloninger, 1992; Starcevic, Uhlenhuth & Fallon, 1995; Battaglia, Przybeck, Bellodi & Cloninger, 1996)]. We may conclude that the de®ning and characteristic feature of cluster C patients with regard to other patients without this type of disorder, would be a behavioural style based on the predominance of passive avoidance behaviours. In relation to this, Fowles (1987) suggested that high anxiety trait individuals would not necessarily be those to suer most from anxiety states, as they would be more likely to avoid ``risk'' situations. In accordance with this hypothesis, and following on from what has been argued above, cluster C patients, owing to their avoidant behavioural style, would encounter a small number of aversive stimuli, resulting in less frequent experiences of anxiety, simply because of their greater tendency to passive avoidance. According to this, the treatment of cluster C patients should involve the modi®cation of their evasive behavioural style, so reducing their sensitivity to aversive stimuli, even when this might mean the greater temporary presence of an anxiety state. In conclusion, our results seem to suggest that cluster C patients are characterised, in comparison with A/B PD or non-PD patients, by a greater activity in the neurobiological structures related to the BIS. This dierence between cluster C patients and other patients can be detected using the SA, PT and SP scales, although the last is the only one to have proved independent of Axis I anxiety and aective symptoms. We therefore propose that, in psychiatric populations, SP may be considered a good psychometric measure of the activity of the BIS. It is certainly interesting that the SP scale which best discriminates between cluster C patients and non-PD patients, independently of Axis I symptoms, is the only one of those used directly constructed from the theoretical assumptions of Gray's model. Other scales evaluating this or similar constructs (e.g. the scales by Carver & White, 1994, the HA, etc.) should be considered in future research. Also, further research should aim to determine if a more active BIS would really be a core vulnerability for cluster C, as hypothesized in this study, or simply an indicator of its presence. In the ®rst case, getting a high score on a scale like SP (i.e. that has proved to be a measure of activity of this system) would not necessarily indicate the presence of a cluster C PD, meaning that a non-psychiatric population might also display the same personality pro®le. In these cases, it might be expected that other factors (i.e. environmental) had acted as safeguards against the development of an Axis II disorder. In the second case, it might ideally be expected that any cluster C PD should lead to a high SP (i.e. sensitivity 1) and a low one in the case of other PD or non-PD individuals (i.e. speci®city 1). Our results do not provide an answer to this question, though personal experience inclines us towards the ®rst of the options. Further research on this matter is currently being considered by our team. Explanatory models of personality underlying PD could guide research and development of pharmacological and behavioural treatments. In the case of cluster C, the anxiety dimension from
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