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Personality and symptom severity in Obsessive–Compulsive Disorder: The mediating role of depression
Personality and Individual Differences 71 (2014) 92–97
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Personality and symptom severity in Obsessive–Compulsive Disorder: The mediating role of depression Clare S. Rees a,⇑, Lynne D. Roberts a, Patricia van Oppen c, Merijn Eikelenboom c, A.A. Jolijn Hendriks c, Anton J.L.M. van Balkom b, Harold van Megen b a b c
School of Psychology and Speech Pathology, Curtin University, Perth, Western Australia, Australia Mental Health Care Institute GGZ Centraal, Ermelo, The Netherlands Department of Health Services Research and Policy, London School of Hygiene and Tropical Medicine, London, United Kingdom
a r t i c l e
i n f o
Article history: Received 27 February 2014 Received in revised form 20 July 2014 Accepted 24 July 2014
Keywords: Obsessive–Compulsive Disorder Longitudinal Personality Chronicity
a b s t r a c t Elevated levels of Neuroticism and lower levels of Extraversion have been reliably shown in patients with anxiety and depressive disorders and some studies have demonstrated these patterns amongst patients diagnosed with Obsessive–Compulsive Disorder (OCD). However, because comorbid anxiety and depression is common in OCD, it is unclear whether the previously observed relationships are due to comorbid anxiety and depression or are more specifically related to the presence of OCD. This study sought to disentangle the relationship between personality and OCD by investigating the relationship between Extraversion, Neuroticism and OCD symptom severity and illness duration. Additionally, we explored the relationship between these variables and the additional variable of depression. Specifically, we tested whether depression mediated these relationships amongst a sample of 322 outpatients diagnosed with OCD. We found that depression fully mediated the relationship between personality and OCD symptom severity but not duration. Indeed, neither personality nor depression could explain illness duration. The results suggest that depression is an important variable to consider when understanding OCD symptom severity and trumps personality variables in terms of its explanatory power. The results also suggest that further work is needed to identify the variables that best explain illness duration in OCD. Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction A key challenge in improving treatment outcomes for people diagnosed with Obsessive–Compulsive Disorder (OCD) is to unravel the factors that might explain higher levels of symptom severity and a more chronic duration of illness. It is well documented that a significant proportion of OCD patients do not respond to the gold-standard treatments and continue to experience ongoing clinical levels of symptoms (Abramowitz, 2006). Efforts to further understand the specific variables that might explain a more chronic course of illness are imperative. One such area of focus is that of personality. A substantial number of studies have now reliably shown a distinct personality profile that broadly distinguishes psychiatric patients from non-patients (Bienvenu et al., 2001; Brown, Chorpita, & Barlow, 1998; Clark & Watson, 1991; Watson & Clark, 1984; Watson, Clark, & Harkness, 1994). Fundamentally, this pattern consists of high Negative Affect (NA)/Neuroticism (N) and low Positive Affect (PA)/Extraversion (E). NA simply refers to ⇑ Corresponding author. Tel.: +41 8 92663442; fax: +41 8 92662464. E-mail address: [email protected] (C.S. Rees). http://dx.doi.org/10.1016/j.paid.2014.07.025 0191-8869/Ó 2014 Elsevier Ltd. All rights reserved.
a tendency to experience a wide range of unpleasant emotional states such as anger, sadness, guilt and fear, whereas PA refers to the tendency to be social, energetic, friendly and gregarious. Studies that have applied the five-factor model of personality have consistently found high levels of Neuroticism and low levels of Extraversion to be associated with both mood and anxiety disorders in community samples (Bienvenu et al., 2001; Brown et al., 1998; Clark & Watson, 1991; Watson et al.,1994). Surprisingly few studies have specifically examined personality profiles among OCD patients using a dimensional approach like the Big Five model of personality. Of the studies conducted to date, the predominant finding has been that when compared to non-clinical samples, those with OCD are higher on Neuroticism, lower on Extraversion and generally higher on Agreeableness (Rector, Hood, Richter, & Bagby, 2002; Rees, Anderson, & Egan, 2006; Samuels et al., 2000; Wu, Clark, & Watson, 2006). Some criticisms of these studies include utilisation of samples where OCD diagnosis was not verified or not current (Samuels et al., 2000) or relatively small sample sizes were utilised (Wu et al., 2006; Rees et al., 2006). Rector et al. (2002) attempted to further explore the dimensional personality traits of OCD patients by controlling for the
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influence of depression. They argued that because the finding of elevated Neuroticism and low Extraversion has been identified as a non-specific vulnerability to anxiety and depressive disorders, controlling for depression could help to elucidate the unique relationship between OCD and these personality traits. They compared 98 patients diagnosed with primary OCD to 98 patients diagnosed with primary Major Depressive Disorder (MDD). Using the Revised NEO Personality Inventory (NEO PI-R, Costa & McCrae, 1992) they found that although both clinical groups had the expected pattern of high Neuroticism and low Extraversion, the MDD group had significantly higher scores on Neuroticism and significantly lower scores on Extraversion than the OCD group. This finding suggests that the high Neuroticism and low Extraversion personality profile, regarded as a non-specific vulnerability to all anxiety and depressive disorders, may in fact vary between specific disorder groups and that depression is an important variable to consider. The association between personality and depression was also demonstrated in another study that utilised a categorical approach to examining the relationship between OCD and personality. Tallis, Rosen, and Shafran (1996) examined comorbidity between OCD and personality disorder diagnosis. They found that when depressive symptomatology was controlled, the number of OCD patients with comorbid personality disorder diagnoses reduced significantly. The results of these studies suggest that high Neuroticism and low Extraversion may be a vulnerability to depression, but not necessarily to OCD. Depression is a highly important variable to consider in its own right when studying OCD because up to 50% of patients present with an additional diagnosis of major depression (MDD) (Crino & Andrews, 1996). OCD patients with comorbid depression who do not respond to treatment have been found to have higher OCD symptom severity than those without the additional diagnosis (Abramowitz & Foa, 1998). It is important to acknowledge the influence of affective temperaments and their potential pathoplastic role in the etiology and clinical characteristics of OCD. Work by Hantouche and Demonfaucon (2008) revealed a constellation of unstable affective temperaments (cyclothymic, irritable and depressive) being associated with treatment-resistant OCD. Studies investigating the temporal relationship between OCD and MDD show that OCD symptoms precede symptoms of depression (Bellodi, Scioto, Diaferia, Ronchi, & Smiraldi, 1992; Demal, Lenz, Mayrhofer, Zapotoczky, & Zitterl, 1993). Bartz and Hollander (2006) draw from this the conclusion that it is unlikely that OCD and depression share an etiological relationship. Whilst extant studies reveal that a diagnosis of OCD is associated with elevated Neuroticism and low Extraversion, no studies have investigated the relationship between these personality traits and OCD symptom severity or illness duration. It may be that those patients with more severe and/or chronic OCD have a different personality profile. Furthermore, it is necessary to conduct such an investigation with a large sample of currently diagnosed patients to have sufficient power for the analysis and to improve upon the generalizability of findings. Also, given the interrelationship between OCD and depression it is imperative to further investigate this particularly with regard to how it relates to personality features, symptom severity and course of illness. There is no doubt that the presence of depression in addition to OCD is associated with greater occupational and functional disability (Markarian et al., 2010). Important questions emerging from the current literature is: Does depression mediate the relationship between personality and OCD? Can depression account for the previously observed differences in levels of Neuroticism and Extraversion? If depression does account for the differences in Neuroticism and Extraversion between OCD patients and non-OCD patients it would suggest that a diagnosis of OCD is not uniquely related to particular personality vulnerabilities.
The following hypotheses were proposed: H1. Participants will have significantly lower scores on Emotional Stability as compared to a normative sample (note: Emotional Stability is equivalent to Neuroticism, thus low Emotional Stability = high Neuroticism).
H2. Participants will have significantly lower scores on Extraversion as compared to a normative sample. H3. Scores on Emotional Stability will be significantly correlated with OCD symptom severity and illness duration. H4. Scores on Extraversion will be significantly correlated with OCD symptom severity and illness duration. H5. Depression will fully mediate the relationship between personality factors (Emotional Stability and Extraversion) and OCD symptom severity. H6. After controlling for age, depression will fully mediate the relationship between personality factors (Emotional Stability and Extraversion) and OCD duration (see Figs. 1 and 2).
2. Method 2.1. Study design This study is part of a large multicentre longitudinal study carried out by the Netherlands Obsessive Compulsive Disorder Association (NOCDA). The NOCDA study aims to investigate the biological, psychological and social determinants of chronicity in OCD by studying patients over a 6-year period (for a full description of the NOCDA study see Schuurmans et al., 2012). All patients diagnosed with OCD who were referred to one of the participating mental health care centres were asked permission to be contacted for research purposes during the intake procedure. All patients who consented were contacted and invited to participate in the study, irrespective of the stage of the disorder, the OCD subtype, the presence of co-morbidity and the stage of chronicity. Personality, depression and OCD were assessed at base-line. Specially trained clinical research staff conducted the baseline interview including the SCID and received a two-day course and regular follow-up one-day training sessions by the fieldwork coordinator. All interviews were constantly monitored by randomly checking at least 10% of all taped interviews.
Extraversion
Depression
Symptom Severity
Emotional Stability Fig. 1. Proposed model with depression mediating the relationship between personality factors and OCD symptom severity.
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1996). Total scores range from 0 to 63. The reliability of the BDIII within the Dutch community has previously been demonstrated through high internal consistency of items (a = 95, N = 7500; Roelofs et al., 2013).
Extraversion
Depression
OCD Duration
4. Results 4.1. Participant sample
Emotional Stability Fig. 2. Proposed model with depression mediating the relationship between personality factors and OCD duration after controlling for age.
2.2. Participants The starting pool of participants were 419 adults with a Lifetime diagnosis of OCD as determined by the administration of the SCID-I (First, Spitzer, Gibbon, & Williams, 1996) who were part of the NOCDA longitudinal study. Participants who did not have a current diagnosis of OCD at the time of recruitment into the study (N = 37), did not have an age of onset recorded (N = 36), who had not completed the personality (N = 19) or depression measures (N = 3) were excluded, leaving a sample of 322 participant cases for analysis. This sample size is sufficient for detecting small to medium size effects with a power of .8 at an alpha level of .05 (G⁄Power 3.1; Faul, Erdfelder, Buchner, & Lang, 2009.
3. Measures 3.1. Demographic questionnaire A structured questionnaire was used to gather information regarding a number of demographic variables including: age, gender, and level of education. Structured Clinical Interview for DSM-IV (SCID-I; First et al., 1996) is a widely used clinician administered interview for diagnosing psychiatric disorders according to DSM-IV. The Dutch version has good inter-rater reliability (Lobbestael, Leurgans, & Arntz, 2011). The Five Factor Personality Inventory (FFPI; Hendriks, Hofstee, & De Raad, 1999a, 1999b) assesses the Big Five factors of personality using 100 brief and concrete items. As well as generating the five personality factors it is also possible to compute 40 bipolar facet scores that are blends of the Big Five factors. The five factors measured by the FFPI are Extraversion (I), Agreeableness (II), Conscientiousness (III), Emotional Stability (IV) and Autonomy (V). Each of the factor scores have shown moderate to high reliability and good construct validity in a variety of samples (Hendriks, Hofstee, & De Raad, 2002; Hendriks, Hofstee, & De Raad, 2011; Hendriks et al., 1999a). In the present sample, the internal consistency reliabilities were .86 for Extraversion, .83 for Agreeableness, .82 for Conscientiousness, .81 for Emotional Stability, and .76 for Autonomy. Yale Brown Obsessive–Compulsive Scale (Y-BOCS; Goodman, Price, Rasmussen, Mazure, Fleischmann, et al., 1989). The Y-BOCS is a clinician-rated, 10-item severity scale, with each item rated from 0 (no symptoms) to 4 (extreme symptoms) (total range 0–40). The scale has excellent inter-rater reliability and high internal consistency (Goodman, Price, Rasmussen, Mazure, Fleischmann, et al., 1989) as well as good convergent and discriminative validity (Goodman, Price, Rasmussen, Mazure, Delgado, et al., 1989) Beck Depression Inventory-II (BDI-II; Beck, Steer, & Brown, 1996). The BDI-II is a 21-item multiple-choice self-report inventory and it is one of the most widely used instruments for measuring the severity of depression and clinical improvements (Beck et al.,
Of these 322 participants, 181 (56.2%) were female and 141 (43.8%) were male. The age at baseline interview ranged from 18 to 79 years (M = 36.27 years, SD = 11.15 years). The majority (98.4%) were Dutch nationals. Years of education completed ranged from 5 to 18 (M = 12.47, SD = 3.09 years). The majority (60.2%) had never married, one third (32.6%) were currently married, 6.5% were divorced and .6% widowed. The age of onset of OCD ranged from four to 46 years (M = 18.10 years, SD = 9.47 years). The duration of OCD at the time of recruitment ranged from 0 to 64 years (M = 18.18 years, SD = 12.36 years). The number of current diagnoses ranged from 1 to 7 (M = 1.93, SD = 1.13; 45.0% = 1 diagnosis), and the number of lifetime diagnoses ranged from 1 to 8 (M = 2.74, SD = 1.47; 21.7% = 1 diagnosis). Just over one third (36.6%) had a concurrent diagnosis of anxiety disorder and almost half (46.9%) had a lifetime diagnosis of anxiety disorder. Just under one fifth (18%) had a concurrent diagnosis of major depressive disorder and more than half (56.5%) had a lifetime diagnosis of major depressive disorder. Descriptive statistics of scores and categories on the key measures are presented in Tables 1–3. Approximately three-quarters of the participants experienced moderate to extreme obsessions and compulsions and mild to severe depression. At the time of recruitment into the study approximately half (49.7%) of participants were currently receiving psychotherapy, one in five (20.5%) were receiving treatment at a hospital (admitted, daytime or part-time) and three in ten (29.2%) were receiving more than one type of treatment. The percentage of participants taking a range of doctor prescribed medications in the previous two weeks is presented in Table 4. Approximately two thirds of participants were prescribed psychotropic medications and two thirds antidepressants. The personality scores of participants can be compared to the normative sample used for establishing norms for the FFPI (Hendriks et al., 1999a, 2011). The personality scores indicate that our OCD sample scores below the general population mean on Extraversion and Emotional Stability. To test the H1, that OCD participants in this sample have significantly lower scores on Emotional Stability as compared to a normative sample, a one-sample t-test was conducted. Participants in this OCD sample scored significantly lower (M = .81, SD = 1.16) than the adult normative sample score (M = 0.82, SD = 1, Hendriks et al., 1999a, 2011): t(321) = 25.25, p < .001, d = 1.41, large effect. To test H2, that OCD participants in this sample have significantly lower scores on Extraversion as compared to a normative
Table 1 Mean, standard deviation and range of scores on key measures (N = 322). Measure
Mean
SD
Range
Y-BOCS Severity obsessions Severity compulsions Severity total score Beck Depression Inventory
10.43 10.67 21.11 15.94
3.99 4.34 7.07 10.02
0–20 0–20 7–40 0–51
.10 .81
1.29 1.16
FFPI Extraversion Emotional Stability
3.39 to 3.03 4.24 to 2.46
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C.S. Rees et al. / Personality and Individual Differences 71 (2014) 92–97 Table 2 FFPI scores by presence/absence of current major depressive disorder (N = 322).
Extraversion Emotional Stability
Total
Current major depressive disorder N = 58
No current major depressive disorder N = 264 .01 (1.28) .62 (1.11)
.61 (1.20) 1.66 (.97)
.10 (1.29) .81 (1.16)
Table 3 Severity categories on Y-BOCS and Beck Depression Inventory (N = 322). Category
Frequency
Percent
5 72 118 102 25
1.6 22.4 36.6 31.7 7.8
96 114 79 33
29.8 35.4 24.5 10.2
a
Y-BOCS Subclinical Mild Moderate Severe Extreme BDIb Normal Mild to moderate Moderate to severe Severe
a Categories from Goodman, Price, Rasmussen, Mazure, Fleischmann, et al. (1989). b Categories from Beck et al. (1996).
Table 4 Percentage of participants taking doctor prescribed medications in previous two weeks by medication type. Medication type
%
Psychotropic Antipsychotic Antidepressant Benzodiazepines
67.1 17.7 62.4 16.8
sample, a one-sample t-test was conducted. Participants in this OCD sample scored significantly lower (M = .10, SD = 1.29) than the adult normative sample score (M = 0.39, SD = 1, Hendriks et al., 1999a, 2011): t(321) = 6.81, p < .001, d = 0.38, small-tomedium effect. Table 2 provides a breakdown of FFPI Extraversion and Emotional Stability scores by whether or not the participant had a current major depressive disorder at the time of inclusion in the study. Participants with a current major depressive order scored significantly lower than those who did not on both Extraversion (t(320) = 3.36, p = .001) and Emotional Stability (t(320 = 6.61, p < .001). To test hypotheses three and four, that scores on Emotional Stability and Extraversion were significantly correlated with OCD symptom severity and illness duration, a correlation matrix was produced (Table 5). Emotional Stability was significantly negatively correlated with symptom severity (Y-BOCS total score;
r = .24, p < .001; small to medium effect size), but not with illness duration (r = .11, p = .06), partially supporting hypothesis 3. Extraversion was significantly negatively correlated with both symptom severity (r = .20, p < .001; small to medium effect size) and illness duration (r = .21, p < .001; small to medium effect size) supporting hypothesis four. In order to test mediation, a number of assumptions need to be met (Baron & Kenny, 1986). The independent, mediator and dependent variables must be significantly associated. As displayed in Table 5, both independent variables (Extraversion and Emotional Stability) were significantly negatively correlated with the mediator variable (depression scores) and one dependent variable (severity of symptoms). The mediator was also associated with both dependent variables. However, as previously noted Emotional Stability was not significantly associated with the second dependent variable (duration). One standard and one hierarchical multiple regression analysis was conducted to test hypothesis five (see Table 6). The results from the standard hierarchical regression demonstrate that in combination, the two personality variables, Extraversion and Emotional Stability, accounted for 52% of the variance in the proposed mediator, BDI total depression scores, R2 = .52, F(2, 319) = 173.11, p < .001. On step one of the hierarchical multiple regression the two personality variables accounted for 7.9% of the variance in OCD symptom severity scores R2 = .08, F(2, 319) = 13.72, p < .001. Both Extraversion and Emotional Stability contributed significant unique variance. On step two of the hierarchical multiple regression BDI depression scores were entered and accounted for a further 16.1% of the variance in symptom severity, DR2 = .09, F(1, 318) = 34.40, p < .001. In total, the three predictor variables accounted for 16.9% of the variance in symptom severity, R2 = .17, F(3, 318) = 21.57, p < .001. Depression was a significant predictor of symptom severity, but neither Extraversion nor Emotional Stability contributed significant unique variance any longer, indicating depression mediated the relationship between personality and OCD symptom severity. Sobel test-statistics confirm that depression significantly mediated the relationship between Extraversion and symptom severity (t = 5.22, p < .001) and Emotional Stability and symptom severity (t = 5.94, p < .001). To further clarify the relationships, path analysis was conducted using LISREL (version 8.8). The path model (see Fig. 3) clearly demonstrates that the impact of the personality variables on symptom severity is fully mediated by depression. As age was significantly correlated with OCD duration (see Table 4), partial correlations between variables, controlling for age were conducted. The results are presented in Table 7. As Extraversion and depression are no longer significantly correlated with OCD duration when partialling out age, hypothesis six cannot be supported. After controlling for age, there is no significant relationship between Extraversion, depression and OCD duration. To further investigate the role of depression, the data file was split into participants with minimal/normal symptom levels on the BDI (<13 n = 96) and levels indicating depression (>13
Table 5 Correlation matrix of key variables (N = 322). Age Age Extraversion Emotional Stability BDI total Y-BOCS total OCD duration * **
Significance level of p < .05. Significance level of p < .01.
Extraversion
Emotional Stability
BDI total
Y-BOCS total
OCD duration
1 .41** .14*
1 .06
1
1 .23** .09 .14* .04 .68**
1 .19** .54** .20** .21**
1 .57** .24** .11
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Table 6 Results of standard multiple regression predicting (1) depression scores and (2) symptom severity scores. Predictor
B[95%CI]
(1) Depression scores Extraversion Emotional Stability
3.48[ 4.08, 4.23[ 4.90,
(2) Symptom severity Step 1 Extraversion Emotional Stability Step 2 Extraversion Emotional Stability Depression (BDI)
sr2
B 2.87] 3.56]
.86[ 1.45, .27] 1.27[ 1.92, .61] .21[ .46,.87] .03[ .73, .79] .31[.20, .41]
.45 .49
.19 .23
.16 .21
.02 .04
.04 .01 .43
.00 .00 .09
Note: B = unstandardized regression coefficient, CI = confidence interval, B = standardised regression coefficient and sr2 = squared semi-partial correlation.
Extraversion
-.45** .19
.02 Depression
Symptom Severity
.48** -.49**
.00
Emotional Stability Fig. 3. Path analysis results testing model with depression mediating the relationship between personality factors and OCD symptom severity. All path coefficients shown are standardised. ⁄⁄ indicates p < .001.
Table 7 Partial correlation matrix of key variables for predicting OCD duration (N = 322). Extraversion Extraversion BDI total OCD duration ⁄⁄
BDI total
OCD duration
1 .06
1
1 .53⁄⁄ .08
indicates p < .001.
n = 226) using established cut-off scores (Beck et al., 1996). In the minimal/normal group, there were no significant relationships between the personality variables and OCD symptom severity. In contrast, in the ‘depressed’ group Extraversion was significantly negatively correlated with OCD symptom severity (r = .14, p = .03) and duration (r = .21, p < . 01) and Emotional Stability was significantly negatively correlated with OCD symptom severity (r = .20, p < .01).
looking at correlations between the presence of a diagnosis of OCD and personality, we examined correlations between OCD symptom severity and personality and found this relationship was completely accounted for by level of depressive symptomatology. This would suggest that an individual diagnosed with OCD may well be exhibiting heightened levels of Neuroticism and lower levels of Extraversion but that this is better explained by the additional presence of significant levels of depression and not just OCD alone. This finding is consistent with Rector et al. (2002) who found that depression was the variable most strongly related to elevated levels of Neuroticism and low Extraversion rather than OCD specifically. The same non-significance of personality variables was found when we split the sample into those with minimal versus those with elevated levels of depression. The former group evidenced no relationship between personality and OCD symptom severity or duration, whereas the latter group showed significant correlations between both Extraversion and Neuroticism (low Emotional Stability) and OCD. Interestingly, once age was controlled for in the analyses none of the personality variables or level of depression was associated with symptom duration. This finding suggests that duration is apparently independent of Neuroticism and Extraversion suggesting that in the etiology of OCD, personality variables do not play an important role. However, the strength of this conclusion must be tempered by the fact that our measure of duration (age–age of onset) does not provide information as to possible periods of time during which an individual may have been symptom free. The strength of this study is that it is one of the largest investigations carried out to date in which personality has been investigated with a large sample of OCD patients with a current diagnosis reliably established using a structured clinical interview. This strengthens the generalisability of the current findings. However, the strength of findings could have been improved by the inclusion of an additional commonly used personality measure and we recommend this action for future studies. The main implication of our results is that the further study of personality and OCD should take into account the influence of depressive symptoms. In particular, it is possible that the elevations seen in previous studies examining personality traits could be state-dependent and may not represent particular vulnerabilities to OCD but rather may be more transient and dependent on depressive symptoms. A further potential explanation for the results is that the personality profile related to OCD (high N, Low E) is in fact mediated not by state levels of depression but by the influence of an underlying affective temperament. The present data suggest that research on the influence of personality profiles on the development of OCD should include the measurement of comorbid levels of depression as well, in order to be able to make proper conclusions on the importance of personality variables in the aetiology of OCD. Acknowledgments
5. Discussion As expected, our large sample of participants with a current diagnosis of OCD showed the typical personality pattern of high Neuroticism (low Emotional Stability) and Introversion (low Extraversion). However, as depression is highly comorbid with OCD and because previous studies had found an influence of depression on observed personality outcomes, we sought to further explore the relationship between personality, depression and OCD. Our hypothesis, that depression would mediate the relationship between Extraversion, Neuroticism and OCD symptom severity was supported. This indicates that simply concluding that high Neuroticism and low Extraversion is significantly associated with OCD does not provide an accurate picture. Instead of simply
The research infrastructure needed to complete the baseline measurements (including personnel and materials) was financed almost exclusively by the participating organizations: Academic department VU Medical Centre/GGZ inGeest, Amsterdam, The Netherlands; Innova Research Centre, Mental Health Care Institute GGZ Centraal, Marinade Wolf Anxiety Research Centre, Ermelo, The Netherlands; Center for Anxiety Disorders ‘‘Overwaal’’, Lent, The Netherlands; Dimence, GGZ Overijssel; Department of Psychiatry, Leiden University Medical Centre, Leiden, The Netherlands; ‘Vincent van Gogh institute’ Mental Health Care Centre Noorden Midden-Limburg, Venray, The Netherlands; Academic Anxiety Center, PsyQ Maastricht University, Division Mental Health and Neuroscience, Maastricht, The Netherlands, except for the fieldwork coordi-
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Hantouche, E. G., & Demonfaucon, C. (2008). Resistant obsessive–compulsive disorder (ROC): Clinical picture, protective factors and influence of affective temperaments. L’Encephale, 34(6), 611–617. Hendriks, A. A. J., Hofstee, W. K. B., & De Raad, B. (1999a). Handleiding bij de fivefactor personality inventory (FFPI) (The five-factor personality inventory: Professional manual). Lisse: Swets Test Services. Hendriks, A. A. J., Hofstee, W. K. B., & De Raad, B. (1999b). The five-factor personality inventory (FFPI). Personality and Individual Differences, 27, 307–325. Hendriks, A. A. J., Hofstee, W. K. B., & De Raad, B. (2011). Handleiding bij de five-factor personality inventory II (FFPI-II) (The five-factor personality inventory II: Professional manual). Houten: Bohn Stafleu van Loghum. Hendriks, A. A. J., Hofstee, W. K. B., & De Raad, B. (2002). The five-factor personality inventory: Assessing the big five by means of brief and concrete statements. In B. de Raad & M. Perugini (Eds.), Big five assessment (pp. 79–108). Göttingen: Hogrefe & Huber. Lobbestael, J., Leurgans, M., & Arntz, A. (2011). Inter-rater reliability of the Structured Clinical Interview for DSM-IV Axis I Disorders (SCID I) and Axis II Disorders (SCID II). Clinical Psychology & Psychotherapy, 18, 75–79. http:// dx.doi.org/10.1002/cpp.693. Markarian, Y., Larson, M. J., Aldea, M. A., Baldwin, S. A., Good, D., Berkeljon, A., et al. (2010). Multiple pathways to functional impairment in obsessive–compulsive disorder. Clinical Psychology Review, 30(1), 78–88. Rector, N. A., Hood, K., Richter, M. A., & Bagby, R. M. (2002). Obsessive–compulsive disorder and the five-factor model of personality: Distinction and overlap with major depressive disorder. Behaviour, Research and Therapy, 40, 1205–1219. Rees, C. S., Anderson, R. A., & Egan, S. J. (2006). Applying the five-factor model of personality to the exploration of the construct of risk-taking in obsessive– compulsive disorder. Behavioural and Cognitive Psychotherapy, 34(1), 31–42. Roelofs, J., van Breukelen, G., de Graaf, L. E., Beck, A. T., Arntz, A., & Huibers, M. J. H. (2013). Norms for the beck depression inventory (BDI-II) in a large Dutch community sample. Journal of Psychopathology and Behavioral Assessment, 35, 93–98. Samuels, J., Nestadt, G., Bienvenu, O. J., Costa, P. T., Riddle, M. A., Liang, K. Y., et al. (2000). Personality disorders and normal personality dimensions in obsessive– compulsive disorder. British Journal of Psychiatry, 177, 457–462. Schuurmans, J., Van Balkom, A. J. L. M., Van Megen, H. J. G. M., Smit, J. H., Eikelenboom, M., Cath, D. C., et al. (2012). The Netherlands Obsessive Compulsive Disorder Association (NOCDA) study: Design and rationale of a longitudinal naturalistic study of the course of OCD and clinical characteristics of the sample at baseline. International Journal of Methods in Psychiatric Research, 21(4), 273–285. Tallis, F., Rosen, K., & Shafran, R. (1996). Investigation into the relationship between personality traits and OCD: A replication employing a clinical population. Behaviour Research & Therapy, 34(8), 649–653. Watson, D., & Clark, L. A. (1984). Negative affectivity: The disposition to experience aversive emotional states. Psychological Bulletin, 96, 465–490. Watson, D., Clark, L. A., & Harkness, A. R. (1994). Structures of personality and their relevance to psychopathology. Journal of Abnormal Psychology, 103, 18–31. Wu, K. D., Clark, L. A., & Watson, D. (2006). Relations between obsessive–compulsive disorder and personality: Beyond axis I–axis II comorbidity. Journal of Anxiety Disorders, 20, 695–717.
Contents lists available at ScienceDirect
Personality and Individual Differences journal homepage: www.elsevier.com/locate/paid
Personality and symptom severity in Obsessive–Compulsive Disorder: The mediating role of depression Clare S. Rees a,⇑, Lynne D. Roberts a, Patricia van Oppen c, Merijn Eikelenboom c, A.A. Jolijn Hendriks c, Anton J.L.M. van Balkom b, Harold van Megen b a b c
School of Psychology and Speech Pathology, Curtin University, Perth, Western Australia, Australia Mental Health Care Institute GGZ Centraal, Ermelo, The Netherlands Department of Health Services Research and Policy, London School of Hygiene and Tropical Medicine, London, United Kingdom
a r t i c l e
i n f o
Article history: Received 27 February 2014 Received in revised form 20 July 2014 Accepted 24 July 2014
Keywords: Obsessive–Compulsive Disorder Longitudinal Personality Chronicity
a b s t r a c t Elevated levels of Neuroticism and lower levels of Extraversion have been reliably shown in patients with anxiety and depressive disorders and some studies have demonstrated these patterns amongst patients diagnosed with Obsessive–Compulsive Disorder (OCD). However, because comorbid anxiety and depression is common in OCD, it is unclear whether the previously observed relationships are due to comorbid anxiety and depression or are more specifically related to the presence of OCD. This study sought to disentangle the relationship between personality and OCD by investigating the relationship between Extraversion, Neuroticism and OCD symptom severity and illness duration. Additionally, we explored the relationship between these variables and the additional variable of depression. Specifically, we tested whether depression mediated these relationships amongst a sample of 322 outpatients diagnosed with OCD. We found that depression fully mediated the relationship between personality and OCD symptom severity but not duration. Indeed, neither personality nor depression could explain illness duration. The results suggest that depression is an important variable to consider when understanding OCD symptom severity and trumps personality variables in terms of its explanatory power. The results also suggest that further work is needed to identify the variables that best explain illness duration in OCD. Ó 2014 Elsevier Ltd. All rights reserved.
1. Introduction A key challenge in improving treatment outcomes for people diagnosed with Obsessive–Compulsive Disorder (OCD) is to unravel the factors that might explain higher levels of symptom severity and a more chronic duration of illness. It is well documented that a significant proportion of OCD patients do not respond to the gold-standard treatments and continue to experience ongoing clinical levels of symptoms (Abramowitz, 2006). Efforts to further understand the specific variables that might explain a more chronic course of illness are imperative. One such area of focus is that of personality. A substantial number of studies have now reliably shown a distinct personality profile that broadly distinguishes psychiatric patients from non-patients (Bienvenu et al., 2001; Brown, Chorpita, & Barlow, 1998; Clark & Watson, 1991; Watson & Clark, 1984; Watson, Clark, & Harkness, 1994). Fundamentally, this pattern consists of high Negative Affect (NA)/Neuroticism (N) and low Positive Affect (PA)/Extraversion (E). NA simply refers to ⇑ Corresponding author. Tel.: +41 8 92663442; fax: +41 8 92662464. E-mail address: [email protected] (C.S. Rees). http://dx.doi.org/10.1016/j.paid.2014.07.025 0191-8869/Ó 2014 Elsevier Ltd. All rights reserved.
a tendency to experience a wide range of unpleasant emotional states such as anger, sadness, guilt and fear, whereas PA refers to the tendency to be social, energetic, friendly and gregarious. Studies that have applied the five-factor model of personality have consistently found high levels of Neuroticism and low levels of Extraversion to be associated with both mood and anxiety disorders in community samples (Bienvenu et al., 2001; Brown et al., 1998; Clark & Watson, 1991; Watson et al.,1994). Surprisingly few studies have specifically examined personality profiles among OCD patients using a dimensional approach like the Big Five model of personality. Of the studies conducted to date, the predominant finding has been that when compared to non-clinical samples, those with OCD are higher on Neuroticism, lower on Extraversion and generally higher on Agreeableness (Rector, Hood, Richter, & Bagby, 2002; Rees, Anderson, & Egan, 2006; Samuels et al., 2000; Wu, Clark, & Watson, 2006). Some criticisms of these studies include utilisation of samples where OCD diagnosis was not verified or not current (Samuels et al., 2000) or relatively small sample sizes were utilised (Wu et al., 2006; Rees et al., 2006). Rector et al. (2002) attempted to further explore the dimensional personality traits of OCD patients by controlling for the
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influence of depression. They argued that because the finding of elevated Neuroticism and low Extraversion has been identified as a non-specific vulnerability to anxiety and depressive disorders, controlling for depression could help to elucidate the unique relationship between OCD and these personality traits. They compared 98 patients diagnosed with primary OCD to 98 patients diagnosed with primary Major Depressive Disorder (MDD). Using the Revised NEO Personality Inventory (NEO PI-R, Costa & McCrae, 1992) they found that although both clinical groups had the expected pattern of high Neuroticism and low Extraversion, the MDD group had significantly higher scores on Neuroticism and significantly lower scores on Extraversion than the OCD group. This finding suggests that the high Neuroticism and low Extraversion personality profile, regarded as a non-specific vulnerability to all anxiety and depressive disorders, may in fact vary between specific disorder groups and that depression is an important variable to consider. The association between personality and depression was also demonstrated in another study that utilised a categorical approach to examining the relationship between OCD and personality. Tallis, Rosen, and Shafran (1996) examined comorbidity between OCD and personality disorder diagnosis. They found that when depressive symptomatology was controlled, the number of OCD patients with comorbid personality disorder diagnoses reduced significantly. The results of these studies suggest that high Neuroticism and low Extraversion may be a vulnerability to depression, but not necessarily to OCD. Depression is a highly important variable to consider in its own right when studying OCD because up to 50% of patients present with an additional diagnosis of major depression (MDD) (Crino & Andrews, 1996). OCD patients with comorbid depression who do not respond to treatment have been found to have higher OCD symptom severity than those without the additional diagnosis (Abramowitz & Foa, 1998). It is important to acknowledge the influence of affective temperaments and their potential pathoplastic role in the etiology and clinical characteristics of OCD. Work by Hantouche and Demonfaucon (2008) revealed a constellation of unstable affective temperaments (cyclothymic, irritable and depressive) being associated with treatment-resistant OCD. Studies investigating the temporal relationship between OCD and MDD show that OCD symptoms precede symptoms of depression (Bellodi, Scioto, Diaferia, Ronchi, & Smiraldi, 1992; Demal, Lenz, Mayrhofer, Zapotoczky, & Zitterl, 1993). Bartz and Hollander (2006) draw from this the conclusion that it is unlikely that OCD and depression share an etiological relationship. Whilst extant studies reveal that a diagnosis of OCD is associated with elevated Neuroticism and low Extraversion, no studies have investigated the relationship between these personality traits and OCD symptom severity or illness duration. It may be that those patients with more severe and/or chronic OCD have a different personality profile. Furthermore, it is necessary to conduct such an investigation with a large sample of currently diagnosed patients to have sufficient power for the analysis and to improve upon the generalizability of findings. Also, given the interrelationship between OCD and depression it is imperative to further investigate this particularly with regard to how it relates to personality features, symptom severity and course of illness. There is no doubt that the presence of depression in addition to OCD is associated with greater occupational and functional disability (Markarian et al., 2010). Important questions emerging from the current literature is: Does depression mediate the relationship between personality and OCD? Can depression account for the previously observed differences in levels of Neuroticism and Extraversion? If depression does account for the differences in Neuroticism and Extraversion between OCD patients and non-OCD patients it would suggest that a diagnosis of OCD is not uniquely related to particular personality vulnerabilities.
The following hypotheses were proposed: H1. Participants will have significantly lower scores on Emotional Stability as compared to a normative sample (note: Emotional Stability is equivalent to Neuroticism, thus low Emotional Stability = high Neuroticism).
H2. Participants will have significantly lower scores on Extraversion as compared to a normative sample. H3. Scores on Emotional Stability will be significantly correlated with OCD symptom severity and illness duration. H4. Scores on Extraversion will be significantly correlated with OCD symptom severity and illness duration. H5. Depression will fully mediate the relationship between personality factors (Emotional Stability and Extraversion) and OCD symptom severity. H6. After controlling for age, depression will fully mediate the relationship between personality factors (Emotional Stability and Extraversion) and OCD duration (see Figs. 1 and 2).
2. Method 2.1. Study design This study is part of a large multicentre longitudinal study carried out by the Netherlands Obsessive Compulsive Disorder Association (NOCDA). The NOCDA study aims to investigate the biological, psychological and social determinants of chronicity in OCD by studying patients over a 6-year period (for a full description of the NOCDA study see Schuurmans et al., 2012). All patients diagnosed with OCD who were referred to one of the participating mental health care centres were asked permission to be contacted for research purposes during the intake procedure. All patients who consented were contacted and invited to participate in the study, irrespective of the stage of the disorder, the OCD subtype, the presence of co-morbidity and the stage of chronicity. Personality, depression and OCD were assessed at base-line. Specially trained clinical research staff conducted the baseline interview including the SCID and received a two-day course and regular follow-up one-day training sessions by the fieldwork coordinator. All interviews were constantly monitored by randomly checking at least 10% of all taped interviews.
Extraversion
Depression
Symptom Severity
Emotional Stability Fig. 1. Proposed model with depression mediating the relationship between personality factors and OCD symptom severity.
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1996). Total scores range from 0 to 63. The reliability of the BDIII within the Dutch community has previously been demonstrated through high internal consistency of items (a = 95, N = 7500; Roelofs et al., 2013).
Extraversion
Depression
OCD Duration
4. Results 4.1. Participant sample
Emotional Stability Fig. 2. Proposed model with depression mediating the relationship between personality factors and OCD duration after controlling for age.
2.2. Participants The starting pool of participants were 419 adults with a Lifetime diagnosis of OCD as determined by the administration of the SCID-I (First, Spitzer, Gibbon, & Williams, 1996) who were part of the NOCDA longitudinal study. Participants who did not have a current diagnosis of OCD at the time of recruitment into the study (N = 37), did not have an age of onset recorded (N = 36), who had not completed the personality (N = 19) or depression measures (N = 3) were excluded, leaving a sample of 322 participant cases for analysis. This sample size is sufficient for detecting small to medium size effects with a power of .8 at an alpha level of .05 (G⁄Power 3.1; Faul, Erdfelder, Buchner, & Lang, 2009.
3. Measures 3.1. Demographic questionnaire A structured questionnaire was used to gather information regarding a number of demographic variables including: age, gender, and level of education. Structured Clinical Interview for DSM-IV (SCID-I; First et al., 1996) is a widely used clinician administered interview for diagnosing psychiatric disorders according to DSM-IV. The Dutch version has good inter-rater reliability (Lobbestael, Leurgans, & Arntz, 2011). The Five Factor Personality Inventory (FFPI; Hendriks, Hofstee, & De Raad, 1999a, 1999b) assesses the Big Five factors of personality using 100 brief and concrete items. As well as generating the five personality factors it is also possible to compute 40 bipolar facet scores that are blends of the Big Five factors. The five factors measured by the FFPI are Extraversion (I), Agreeableness (II), Conscientiousness (III), Emotional Stability (IV) and Autonomy (V). Each of the factor scores have shown moderate to high reliability and good construct validity in a variety of samples (Hendriks, Hofstee, & De Raad, 2002; Hendriks, Hofstee, & De Raad, 2011; Hendriks et al., 1999a). In the present sample, the internal consistency reliabilities were .86 for Extraversion, .83 for Agreeableness, .82 for Conscientiousness, .81 for Emotional Stability, and .76 for Autonomy. Yale Brown Obsessive–Compulsive Scale (Y-BOCS; Goodman, Price, Rasmussen, Mazure, Fleischmann, et al., 1989). The Y-BOCS is a clinician-rated, 10-item severity scale, with each item rated from 0 (no symptoms) to 4 (extreme symptoms) (total range 0–40). The scale has excellent inter-rater reliability and high internal consistency (Goodman, Price, Rasmussen, Mazure, Fleischmann, et al., 1989) as well as good convergent and discriminative validity (Goodman, Price, Rasmussen, Mazure, Delgado, et al., 1989) Beck Depression Inventory-II (BDI-II; Beck, Steer, & Brown, 1996). The BDI-II is a 21-item multiple-choice self-report inventory and it is one of the most widely used instruments for measuring the severity of depression and clinical improvements (Beck et al.,
Of these 322 participants, 181 (56.2%) were female and 141 (43.8%) were male. The age at baseline interview ranged from 18 to 79 years (M = 36.27 years, SD = 11.15 years). The majority (98.4%) were Dutch nationals. Years of education completed ranged from 5 to 18 (M = 12.47, SD = 3.09 years). The majority (60.2%) had never married, one third (32.6%) were currently married, 6.5% were divorced and .6% widowed. The age of onset of OCD ranged from four to 46 years (M = 18.10 years, SD = 9.47 years). The duration of OCD at the time of recruitment ranged from 0 to 64 years (M = 18.18 years, SD = 12.36 years). The number of current diagnoses ranged from 1 to 7 (M = 1.93, SD = 1.13; 45.0% = 1 diagnosis), and the number of lifetime diagnoses ranged from 1 to 8 (M = 2.74, SD = 1.47; 21.7% = 1 diagnosis). Just over one third (36.6%) had a concurrent diagnosis of anxiety disorder and almost half (46.9%) had a lifetime diagnosis of anxiety disorder. Just under one fifth (18%) had a concurrent diagnosis of major depressive disorder and more than half (56.5%) had a lifetime diagnosis of major depressive disorder. Descriptive statistics of scores and categories on the key measures are presented in Tables 1–3. Approximately three-quarters of the participants experienced moderate to extreme obsessions and compulsions and mild to severe depression. At the time of recruitment into the study approximately half (49.7%) of participants were currently receiving psychotherapy, one in five (20.5%) were receiving treatment at a hospital (admitted, daytime or part-time) and three in ten (29.2%) were receiving more than one type of treatment. The percentage of participants taking a range of doctor prescribed medications in the previous two weeks is presented in Table 4. Approximately two thirds of participants were prescribed psychotropic medications and two thirds antidepressants. The personality scores of participants can be compared to the normative sample used for establishing norms for the FFPI (Hendriks et al., 1999a, 2011). The personality scores indicate that our OCD sample scores below the general population mean on Extraversion and Emotional Stability. To test the H1, that OCD participants in this sample have significantly lower scores on Emotional Stability as compared to a normative sample, a one-sample t-test was conducted. Participants in this OCD sample scored significantly lower (M = .81, SD = 1.16) than the adult normative sample score (M = 0.82, SD = 1, Hendriks et al., 1999a, 2011): t(321) = 25.25, p < .001, d = 1.41, large effect. To test H2, that OCD participants in this sample have significantly lower scores on Extraversion as compared to a normative
Table 1 Mean, standard deviation and range of scores on key measures (N = 322). Measure
Mean
SD
Range
Y-BOCS Severity obsessions Severity compulsions Severity total score Beck Depression Inventory
10.43 10.67 21.11 15.94
3.99 4.34 7.07 10.02
0–20 0–20 7–40 0–51
.10 .81
1.29 1.16
FFPI Extraversion Emotional Stability
3.39 to 3.03 4.24 to 2.46
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C.S. Rees et al. / Personality and Individual Differences 71 (2014) 92–97 Table 2 FFPI scores by presence/absence of current major depressive disorder (N = 322).
Extraversion Emotional Stability
Total
Current major depressive disorder N = 58
No current major depressive disorder N = 264 .01 (1.28) .62 (1.11)
.61 (1.20) 1.66 (.97)
.10 (1.29) .81 (1.16)
Table 3 Severity categories on Y-BOCS and Beck Depression Inventory (N = 322). Category
Frequency
Percent
5 72 118 102 25
1.6 22.4 36.6 31.7 7.8
96 114 79 33
29.8 35.4 24.5 10.2
a
Y-BOCS Subclinical Mild Moderate Severe Extreme BDIb Normal Mild to moderate Moderate to severe Severe
a Categories from Goodman, Price, Rasmussen, Mazure, Fleischmann, et al. (1989). b Categories from Beck et al. (1996).
Table 4 Percentage of participants taking doctor prescribed medications in previous two weeks by medication type. Medication type
%
Psychotropic Antipsychotic Antidepressant Benzodiazepines
67.1 17.7 62.4 16.8
sample, a one-sample t-test was conducted. Participants in this OCD sample scored significantly lower (M = .10, SD = 1.29) than the adult normative sample score (M = 0.39, SD = 1, Hendriks et al., 1999a, 2011): t(321) = 6.81, p < .001, d = 0.38, small-tomedium effect. Table 2 provides a breakdown of FFPI Extraversion and Emotional Stability scores by whether or not the participant had a current major depressive disorder at the time of inclusion in the study. Participants with a current major depressive order scored significantly lower than those who did not on both Extraversion (t(320) = 3.36, p = .001) and Emotional Stability (t(320 = 6.61, p < .001). To test hypotheses three and four, that scores on Emotional Stability and Extraversion were significantly correlated with OCD symptom severity and illness duration, a correlation matrix was produced (Table 5). Emotional Stability was significantly negatively correlated with symptom severity (Y-BOCS total score;
r = .24, p < .001; small to medium effect size), but not with illness duration (r = .11, p = .06), partially supporting hypothesis 3. Extraversion was significantly negatively correlated with both symptom severity (r = .20, p < .001; small to medium effect size) and illness duration (r = .21, p < .001; small to medium effect size) supporting hypothesis four. In order to test mediation, a number of assumptions need to be met (Baron & Kenny, 1986). The independent, mediator and dependent variables must be significantly associated. As displayed in Table 5, both independent variables (Extraversion and Emotional Stability) were significantly negatively correlated with the mediator variable (depression scores) and one dependent variable (severity of symptoms). The mediator was also associated with both dependent variables. However, as previously noted Emotional Stability was not significantly associated with the second dependent variable (duration). One standard and one hierarchical multiple regression analysis was conducted to test hypothesis five (see Table 6). The results from the standard hierarchical regression demonstrate that in combination, the two personality variables, Extraversion and Emotional Stability, accounted for 52% of the variance in the proposed mediator, BDI total depression scores, R2 = .52, F(2, 319) = 173.11, p < .001. On step one of the hierarchical multiple regression the two personality variables accounted for 7.9% of the variance in OCD symptom severity scores R2 = .08, F(2, 319) = 13.72, p < .001. Both Extraversion and Emotional Stability contributed significant unique variance. On step two of the hierarchical multiple regression BDI depression scores were entered and accounted for a further 16.1% of the variance in symptom severity, DR2 = .09, F(1, 318) = 34.40, p < .001. In total, the three predictor variables accounted for 16.9% of the variance in symptom severity, R2 = .17, F(3, 318) = 21.57, p < .001. Depression was a significant predictor of symptom severity, but neither Extraversion nor Emotional Stability contributed significant unique variance any longer, indicating depression mediated the relationship between personality and OCD symptom severity. Sobel test-statistics confirm that depression significantly mediated the relationship between Extraversion and symptom severity (t = 5.22, p < .001) and Emotional Stability and symptom severity (t = 5.94, p < .001). To further clarify the relationships, path analysis was conducted using LISREL (version 8.8). The path model (see Fig. 3) clearly demonstrates that the impact of the personality variables on symptom severity is fully mediated by depression. As age was significantly correlated with OCD duration (see Table 4), partial correlations between variables, controlling for age were conducted. The results are presented in Table 7. As Extraversion and depression are no longer significantly correlated with OCD duration when partialling out age, hypothesis six cannot be supported. After controlling for age, there is no significant relationship between Extraversion, depression and OCD duration. To further investigate the role of depression, the data file was split into participants with minimal/normal symptom levels on the BDI (<13 n = 96) and levels indicating depression (>13
Table 5 Correlation matrix of key variables (N = 322). Age Age Extraversion Emotional Stability BDI total Y-BOCS total OCD duration * **
Significance level of p < .05. Significance level of p < .01.
Extraversion
Emotional Stability
BDI total
Y-BOCS total
OCD duration
1 .41** .14*
1 .06
1
1 .23** .09 .14* .04 .68**
1 .19** .54** .20** .21**
1 .57** .24** .11
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Table 6 Results of standard multiple regression predicting (1) depression scores and (2) symptom severity scores. Predictor
B[95%CI]
(1) Depression scores Extraversion Emotional Stability
3.48[ 4.08, 4.23[ 4.90,
(2) Symptom severity Step 1 Extraversion Emotional Stability Step 2 Extraversion Emotional Stability Depression (BDI)
sr2
B 2.87] 3.56]
.86[ 1.45, .27] 1.27[ 1.92, .61] .21[ .46,.87] .03[ .73, .79] .31[.20, .41]
.45 .49
.19 .23
.16 .21
.02 .04
.04 .01 .43
.00 .00 .09
Note: B = unstandardized regression coefficient, CI = confidence interval, B = standardised regression coefficient and sr2 = squared semi-partial correlation.
Extraversion
-.45** .19
.02 Depression
Symptom Severity
.48** -.49**
.00
Emotional Stability Fig. 3. Path analysis results testing model with depression mediating the relationship between personality factors and OCD symptom severity. All path coefficients shown are standardised. ⁄⁄ indicates p < .001.
Table 7 Partial correlation matrix of key variables for predicting OCD duration (N = 322). Extraversion Extraversion BDI total OCD duration ⁄⁄
BDI total
OCD duration
1 .06
1
1 .53⁄⁄ .08
indicates p < .001.
n = 226) using established cut-off scores (Beck et al., 1996). In the minimal/normal group, there were no significant relationships between the personality variables and OCD symptom severity. In contrast, in the ‘depressed’ group Extraversion was significantly negatively correlated with OCD symptom severity (r = .14, p = .03) and duration (r = .21, p < . 01) and Emotional Stability was significantly negatively correlated with OCD symptom severity (r = .20, p < .01).
looking at correlations between the presence of a diagnosis of OCD and personality, we examined correlations between OCD symptom severity and personality and found this relationship was completely accounted for by level of depressive symptomatology. This would suggest that an individual diagnosed with OCD may well be exhibiting heightened levels of Neuroticism and lower levels of Extraversion but that this is better explained by the additional presence of significant levels of depression and not just OCD alone. This finding is consistent with Rector et al. (2002) who found that depression was the variable most strongly related to elevated levels of Neuroticism and low Extraversion rather than OCD specifically. The same non-significance of personality variables was found when we split the sample into those with minimal versus those with elevated levels of depression. The former group evidenced no relationship between personality and OCD symptom severity or duration, whereas the latter group showed significant correlations between both Extraversion and Neuroticism (low Emotional Stability) and OCD. Interestingly, once age was controlled for in the analyses none of the personality variables or level of depression was associated with symptom duration. This finding suggests that duration is apparently independent of Neuroticism and Extraversion suggesting that in the etiology of OCD, personality variables do not play an important role. However, the strength of this conclusion must be tempered by the fact that our measure of duration (age–age of onset) does not provide information as to possible periods of time during which an individual may have been symptom free. The strength of this study is that it is one of the largest investigations carried out to date in which personality has been investigated with a large sample of OCD patients with a current diagnosis reliably established using a structured clinical interview. This strengthens the generalisability of the current findings. However, the strength of findings could have been improved by the inclusion of an additional commonly used personality measure and we recommend this action for future studies. The main implication of our results is that the further study of personality and OCD should take into account the influence of depressive symptoms. In particular, it is possible that the elevations seen in previous studies examining personality traits could be state-dependent and may not represent particular vulnerabilities to OCD but rather may be more transient and dependent on depressive symptoms. A further potential explanation for the results is that the personality profile related to OCD (high N, Low E) is in fact mediated not by state levels of depression but by the influence of an underlying affective temperament. The present data suggest that research on the influence of personality profiles on the development of OCD should include the measurement of comorbid levels of depression as well, in order to be able to make proper conclusions on the importance of personality variables in the aetiology of OCD. Acknowledgments
5. Discussion As expected, our large sample of participants with a current diagnosis of OCD showed the typical personality pattern of high Neuroticism (low Emotional Stability) and Introversion (low Extraversion). However, as depression is highly comorbid with OCD and because previous studies had found an influence of depression on observed personality outcomes, we sought to further explore the relationship between personality, depression and OCD. Our hypothesis, that depression would mediate the relationship between Extraversion, Neuroticism and OCD symptom severity was supported. This indicates that simply concluding that high Neuroticism and low Extraversion is significantly associated with OCD does not provide an accurate picture. Instead of simply
The research infrastructure needed to complete the baseline measurements (including personnel and materials) was financed almost exclusively by the participating organizations: Academic department VU Medical Centre/GGZ inGeest, Amsterdam, The Netherlands; Innova Research Centre, Mental Health Care Institute GGZ Centraal, Marinade Wolf Anxiety Research Centre, Ermelo, The Netherlands; Center for Anxiety Disorders ‘‘Overwaal’’, Lent, The Netherlands; Dimence, GGZ Overijssel; Department of Psychiatry, Leiden University Medical Centre, Leiden, The Netherlands; ‘Vincent van Gogh institute’ Mental Health Care Centre Noorden Midden-Limburg, Venray, The Netherlands; Academic Anxiety Center, PsyQ Maastricht University, Division Mental Health and Neuroscience, Maastricht, The Netherlands, except for the fieldwork coordi-
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