Relationship between the five-factor model of personality and unipolar, bipolar and schizophrenic patients

Psychiatry Research 70 Ž1997. 83]94

Relationship between the five-factor model of personality and unipolar, bipolar and schizophrenic patients R. Michael Bagby a,U , Kirstin D. Bindseil a , Deborah R. Schuller a , Neil A. Rector a , L. Trevor Young b , Robert G. Cookea , Mary V. Seemana , Elizabeth A. McCay a , Russell T. Joffe b a

Clarke Institute of Psychiatry, 250 College St., Toronto, Ontario, Canada M5T 1R8 b McMaster Uni®ersity Medical Centre, Hamilton, Ontario, Canada Received 12 August 1996; revised 17 January 1997; accepted 3 March 1997

Abstract The purpose of this study was to examine personality differences among three different Axis I disorders } recovered patients with unipolar depression Ž n s 62., euthymic patients with bipolar disorder Ž n s 34., and patients with schizophrenia in the residual phase of their illness Ž n s 41. using the five-factor model of personality ŽFFM.. The dimensions of the FFM ] Neuroticism ŽN., Extraversion ŽE., Openness ŽO., Agreeableness ŽA., and Conscientiousness ŽC. ] were measured with composite scores derived from the NEO Personality Inventory ŽNEO PI. and the Revised NEO Personality Inventory ŽNEO PI-R.. While no group differences emerged on N or C, the bipolar patients scored significantly higher on the Positive Emotion facet Žsubscale . of E than the unipolar patients. The schizophrenic patients scored lower on the Feelings, Values and Actions facets of O than did the unipolar and bipolar patients. The unipolar patients scored higher on A than the schizophrenic patients. Q 1997 Elsevier Science Ireland Ltd. Keywords: Depression; Bipolar disorder; Schizophrenia; Personality

U

Corresponding author. Tel.: q1 416 9796939; fax: q1 416 9796821; e-mail: [email protected]

0165-1781r97r$17.00 Q 1997 Elsevier Science Ireland Ltd. All rights reserved. PII S0165-1781Ž97. 03096-5

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1. The relationship between the five-factor model of personality and unipolar, bipolar and schizophrenic patients In the past 10 years there has been an accumulation of data indicating that the five-factor model of personality ŽFFM. can account for many of the individual differences in personality in normal adults ŽCosta and McCrae, 1992a,b; Trull, 1992.. However, its applicability to clinical populations has only recently been examined. The dimensions included in the FFM include: Neuroticism ŽN., Extraversion ŽE., Openness to Experience ŽO., Agreeableness ŽA. and Conscientiousness ŽC.. N is the predisposition to experience psychological stress as manifested by anxiety, anger, depression or other negative affects; E includes sociability, liveliness, and cheerfulness; O is seen as aesthetic sensitivity, intellectual curiosity, need for variety, and non-dogmatic attitudes; A involves trust, altruism, and sympathy; and C encompasses a disciplined striving after goals and a strict adherence to principles ŽCosta and McCrae, 1992b.. The NEO PI ŽCosta and McCrae, 1989. and its revised version, the NEO PI-R ŽCosta and McCrae, 1992b., were specifically designed to test the five-factor model ŽFFM . of personality. Whilenumerous studies have explored personality characteristics using the FFM in non-clinical samples and in samples of psychiatric patients with Axis II disorders, comparatively few studies have examined the FFM in relation to Axis I disorders. The present study examined the relationship between the FFM and three major Axis I disorders } unipolar depression, bipolar disorder, and schizophrenia. All patients were diagnosed using standardized, structured interviews and were in a remitted phase of their illness. Personality and Axis I disorders can interact in several ways; for example, personality can: Ža. serve as a vulnerability or pre-dispositional factor to a particular disorder; Žb. be modified by the disorder Žpathoplasty.; Žc. be distorted temporarily by the presence of the disorder; or Žd. be direct expressions of the disorder. While a crosssectional study cannot, on its own, disentangle these issues, we used patients who were in the

remitted phase of their illness in order to rule out, at least in part, possibilities Žc. and Žd. outlined above. As the patients in this study were not acutely ill, their personality can neither be currently distorted by nor be an expression of a disorder, and while one cannot rule out entirely the possibility of Žb. or find unequivocal support for Ža., recent longitudinal and prospective studies have indicated that personality is not necessarily modified by previous depressive episodes ŽDuggan et al., 1991; Shea et al., 1996., and that personality can predispose to a depressive episode ŽSurtees and Wainwright, 1996.. With respect to bipolar disorder, Bagby et al. Ž1996a. recently reported that personality scores were not altered by the previous number of manic episodes. As for schizophrenia, Berenbaum and Fujita Ž1994., in a comprehensive review, cite a number of different studies wherein personality scores remained relatively stable in a large sample of schizophrenics who were examined during hospitalization, at discharge and some 9 months following discharge. They also cite prospective studies in which personality scores showed a strong trend to predict the subsequent development of schizophrenia. Based on these findings, we believe that personality differences across different diagnostic patient groups who are in remission permit reliable inferences about their personality traits. We derived several hypotheses about the differences among these groups of patients for each of the five dimensions. For the N dimension, we expected all three groups of patients to be similar. This hypothesis was based on the assumption that N is a non-specific vulnerability factor for psychopathology ŽCosta and McCrae, 1992a,b; Widiger and Trull, 1992; Trull and Sher, 1994.. This hypothesis was also based on results from numerous empirical studies indicating that patients with unipolar depression, whether acutely ill or recovered from a depressive episode, score higher on N than a normative comparison sample ŽHirschfeld and Klerman, 1979; Hirschfeld et al., 1983a,b, 1989; Barnett and Gotlib, 1988; Widiger andTrull, 1992; Bagby et al., 1995., and patients with bipolar disorder score higher on neuroticism ŽHirschfeld et al., 1986a; Roy, 1990. compared to

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‘normal’ non-clinical comparison samples. Berenbaum and Fujita Ž1994. reported from their meta-analysis that schizophrenic patients score higher on neuroticism than both normal participants and neurotic patients who represented a heterogeneous diagnostic group, ranging from non-psychotic outpatients to individuals with ‘reactive depressions’. We also predicted that patients with bipolar disorder would score higher on the E dimension than patients with either unipolar depression or schizophrenia, while the two latter groups would not differ from each another. This prediction was based on the empirical literature indicating that patients with unipolar depression typically score lower on E than a non-clinical comparison sample ŽHirschfeld and Klerman, 1979; Hirschfeld et al., 1983a, 1989; Barnett and Gotlib, 1988; Widiger and Trull, 1992; Bagby et al., 1995., and that patients with bipolar disorder do not differ from non-clinical comparison samples, although they do score higher than patients with unipolar depression ŽHirschfeld and Klerman, 1979; Liebowitz et al., 1979; Hirschfeld et al., 1986b.. It was also predicted that patients with schizophrenia would score lower on E, based on the results from the recent meta-analysis by Berenbaum and Fujita Ž1994.. There are only a few studies that have used conceptually similar constructs to the FFM dimensions of O, C and A. The Thoughtfulness scale from the Guilford Zimmerman Temperament Survey ŽGZTS; Guilford et al., 1976., which is conceptually similar to the O dimension of the FFM ŽCosta and McCrae, 1992a., has been found to be moderately correlated with O ŽCosta and McCrae, 1992b.. In the one study examining differences between patients with unipolar and bipolar disorders using the Thoughtfulness scale, Hirschfeld et al. Ž1986a. reported that only women with unipolar depression scored lower on this scale than did a non-clinical comparison sample of women. In a more recent study, Young et al. Ž1995. found that patients with bipolar disorder scored significantly higher on the Novelty Seeking dimension of the Tri-dimensional Personality Questionnaire ŽTPQ; Cloninger, 1987. than did the

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unipolar depressed patients. Although Young et al. Ž1995. note that the Novelty Seeking dimension is related to E, there is also conceptual overlap between the Novelty Seeking dimension and O. Berenbaum and Fujita Ž1994. suggested that patients with schizophrenia, theoretically, should score high on O because these patients have displayed eccentric perceptions which have been reported to correlate with the O dimension. However, Tien et al. Ž1992. reported that two personality disorders which are conceptually related to schizophrenia } schizotypal and schizoid disorders } were associated with lower, not higher scores on the O dimension. Yeung et al. Ž1993. also found no differences on O between relatives with atypical psychosis compared with a schizophrenia sample. In sum, there are some indications that the O dimension may distinguish between unipolar, bipolar and schizophrenic patients, but the literature is far from definitive and no specific predictions could be made. The literature on the relationship of C and A to patients with unipolar disorder, bipolar disorder and schizophrenia is equally inconclusive. In an earlier article, Klein and Depue Ž1985. suggested that bipolar disorder patients tend to exhibit higher levels of obsessional personality traits } a trait that overlaps partially with the C dimension } than do normal subjects. An earlier study by Matussekand Feil Ž1983. found that patients with bipolar disorder exhibited significantly greater obsessionality than did normal controls; unipolars did not. However, Hirschfeld et al. Ž1986a. were not able to replicate these findings. In the studies that have measured the C dimension in schizoid and schizotypal disorders, neither Tien et al. Ž1992., nor Yeung et al. Ž1993. found C to be related to either schizotypal or schizoid disorders. Yeung et al. Ž1993. did report that relatives with atypical psychosis tend to have lower Agreeableness scores com pared to the schizophrenia sample. Based on this review, we could not make any firm predictions with respect to the differences among patients with unipolar depression, bipolar disorder, or schizophrenia on C and A.

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2. Method 2.1. Participants The sample consisted of 137 psychiatric outpatients Ž56 men, 81 women.. Of these, 62 Ž22 men, 40 women. were recovered patients with unipolar depression, 34 Ž9 men, 25 women. were euthymic patients with bipolar disorder, and 41 Ž25 men, 16 women. were patients with schizophrenia in the residual phase of their illness. All patients met DSM-III-R criteria for either unipolar, non-psychotic depression, bipolar disorder, or schizophrenia. The unipolar and bipolar disorder patients were diagnosed on the basis of information obtained using the Schedule for Affective Disorders and Schizophrenia-Lifetime version ŽSADS-L; Spitzer and Endicott, 1979.. The schizophrenic patients were diagnosed using the Structured Clinical Interview for the Diagnostic and Statistical Manual of Mental Disorders } Third Edition } Revised ŽSCID III-R; Spitzer et al., 1988.. The recovered depressed patients were recruited into a clinical database maintained at the Mood Disorders Clinic, Clarke Institute of Psychiatry from June 1991 until June 1994. All patients were entered into the database when depressed. To be eligible for entry into the database, all patients had to be medication-free for a minimum of 2 weeks prior to the initiation of treatment and could not be suffering from a concurrent medical illness. The bipolar patients were drawn from patients newly enrolled in the Bipolar Clinic of the Clarke Institute of Psychiatry beginning January 1, 1992. All patients had a DSM-III-R diagnosis of bipolar disorder, and were free of concurrent acute medical morbidity. Personality questionnaires were administered beginning in January 1993 to all patients who had been euthymic for at least 1 month. The patients with schizophrenia were recruited from the Schizophrenia Research Registry of Toronto. The members of the Registry have been previously diagnosed and all had given consent to be contacted for potential research projects. For

this study, patients were contacted by telephone, given a brief description of the study and if they expressed an interest, a testing session was scheduled. Approximately two-thirds of those patients contacted agreed to participate. All testing was done from June 1995 until December 1995. To assess the severity of depression and mania for the unipolar and bipolar disorder patients, respectively, we used the 17-item Hamilton Rating Scale for Depression ŽHRSD; Hamilton, 1967., and the Young Mania Scale ŽYMS; Young et al., 1978.. Symptom severity for the schizophrenia patient sample was assessed by the Positive and Negative Syndrome Scale for Schizophrenia ŽPANNS; Kay et al., 1987.. For the unipolar patients, recovery was defined as a ) 50% reduction on the HRSD with a final score of - 10 after at least 5 weeks and no more than 12 weeks of treatment. For the bipolar patients, recovery was defined as an HRSD score - 10 and a YMS score - 10, and a period of euthymia of at least 1 month as determined by clinical interview. For the schizophrenic patients, the residual status of their condition was based on both a clinical interview and positive and negative scores - 14 and - 17, respectively, on the PANSS. The unipolar patients scored significantly higher on the HRSD than did the bipolar patients, M s 4.12, S.D.s 2.49 vs. M s 2.62, S.D.s 2.77, t Ž94. s 2.43, P0.05. 2.2. Personality measures Either the NEO Personality Inventory ŽNEO PI; Costa and McCrae, 1989. or the Revised NEO Personality Inventory ŽNEO PI-R; Costa and McCrae, 1992a,b. was administered to all patients. The NEO PI, which consists of 181 self-report items answered on a five-point Likert scale, was specifically designed to measure the FFM. Three scales measuring N, E, and O dimensions each comprise six separate facet scales, while A and C have no such facet scales. The NEO PI-R added facet scales to A and C and replaced 10 of the original items on N, E and O } which now consists of 240 items. The unipolar patients completed the NEO PI, and the bipolar and

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schizophrenic patients completed the NEO PI-R. Composite scores for each of the five dimensions were created by extracting and summing the 167 items common to both the NEO PI and NEO PI-R scales. Because the NEO PI does not have facet scales for the A and C dimensions, we were only able to derive facet composite scales for the N, E, and O dimensions. The facets for N include anxiety, angry hostility, depression, self-consciousness, impulsiveness and vulnerability; the facets for E include gregariousness, warmth, assertiveness, activity, excitement-seeking and positive emotion; the facets for O include openness to fantasy, aesthetics, feelings, acting, ideas and values. These composite and dimension scores have been found to be virtually identical to the NEO PI and NEO PI-R dimension and facet scores ŽBagby et al., 1996a,b..

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using a one-way analysis of variance; individual differences between patient groups were determined using the Scheffe ´ procedure Ž P- 0.01.. There were differences among the patient groups for years of education and socioeconomic status, with the unipolar and bipolar patients having significantly higher levels of education and socioeconomic status than the schizophrenic patients. There were also significant differences among the groups of patients for age at first episode, with the schizophrenic patients having an earlier age of onset compared to the unipolar group. Number of episodes for unipolar and bipolar patients was defined by number of times patients previously met criteria for these disorders. The number of episodes for the schizophrenic patients was based on discrete episodes which required hospitalization. There were significant differences among the groups of patients for a previous number of episodes, with the bipolar and schizophrenic patients experiencing significantly more previous episodesthan the unipolar patients. A chi square analysis indicated significant differences in the proportion of men and women across the three patient groups, x 2 Ž2. s 10.54, P- 0.01, with more

3. Results 3.1. Demographics and clinical characteristics Table 1 displays the demographics and clinical characteristics for the three groups of patients. Differences among patient groups were assessed

Table 1 Demographic and clinical characteristics for the recovered unipolar depression, bipolar disorder, and schizophrenia patients Unipolar Ž n s 62.

Age Years of education Socioeconomic status Age at first episode Number of previous episodes HRSD Ž17-item. YMS PANSS Positive symptoms Negative symptoms

Bipolar Ž n s 34.

Schizophrenia Ž n s 41.

M

S.D.

M

S.D.

M

S.D.

F Ž2,103.

38.92 ab c 15.15ab 51.43ab 28.30 ab 2.80 a 4.12 a }

10.36 3.60 13.44 11.40 2.50 2.49 }

37.70 abc 15.84ab 53.16 ab 25.82 abc 5.71bc 2.62 b 0.83

10.45 3.27 8.41 8.39 8.90 2.77 1.64

40.32 abc 13.44 c 36.09 c 21.13bc 5.50 bc } }

8.07 2.62 16.65 4.26 4.52 } }

0.67 5.58UU 7.20UU 7.66UU 3.87 5.90U }

} }

} }

} }

} }

11.57 12.90

4.90 6.21

} }

Abbre®iations: HRSD, Hamilton Rating Scale for Depression; YMS, Young Mania Scale; PANSS, Positive and Negative Syndrome Scale for Schizophrenia. Socioeconomic status ŽSES. measured by the Blishen Index, a SES index designed for the Canadian population ŽBlishen et al., 1987.. Means in the same row that do not share superscripts differ significantly where P- 0.01. The difference for HRSD score between the unipolar and bipolar patients was calculated with a t-test Žd.f.s 95..

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women in the unipolar and bipolar patient groups and more men in the group of schizophrenic patients. 3.2. Personality differences Fig. 1 displays the personality profiles for each of the disorders. A two Žgender. = three Žpatient group. multivariate analysis of variance was performed to determine if there were gender differences across the groups of patients for each of the five personality dimensions. There was no significant overall multivariate interaction effect for the five dimensions, nor was there a significant main effect for gender; therefore, all subse-

quent analyses were performed combining the men and women so as to maximize statistical power. To assess group differences, a multivariate analysis of variance was performed for the personality dimensions N, E, and O, as each of these dimensions. The significance level for the comparisons of the dimensions was set at P - 0.05. Univariate analysis of variance was performed for each of the facets within the dimensions; given the number of comparisons, the significance level was set at P- 0.01. Univariate analysis of variance was performed to assess differences among the three groups on A and C; the level was set at P- 0.05. Table 2 displays the raw and T-scores

Fig. 1. Personality profiles for each of the disorders.

R.M. Bagby et al. r Psychiatry Research 70 (1997) 83]94

for each dimension and corresponding facets. There were no significant differences among the three groups for N or C. Significant differences among the patient groups for E, Wilk’s l s 0.807, approximately F Ž12,258. s 2.44, P - 0.005; O, Wilk’s l s 0.702, approximately F Ž12,258. s 4.16, P- 0.001; and A, F Ž2,134. s 3.04, P- 0.05. Only one facet of the E dimension, Positive Emotions, reached significance, F Ž2,134. s 4.48, P- 0.01, on which bipolar patients scored significantly higher than did unipolar patients. Because significant differences between the unipolar

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and bipolar patients were found for severity of depression, a series of hierarchical regression analyses were performed. In this analysis, patient groupŽi.e. unipolar, bipolar. served as the dependent variable. HRSD scores and the Positive Emotions facet of E served as the independent variables. This facet Žvs. the entire dimension of E. was used as it was the only significant facet from this dimension. In order to determine whether the Positive Emotions facet contributed to the difference between the unipolar and bipolar patients beyond the contribution of severity of

Table 2 Means and standard deviations of the five dimensions of the NEO-PI for unipolar depression, bipolar disorder and schizophrenia patients Unipolar Ž n s 62.

Bipolar Ž n s 34.

M

S.D.

T

Neuroticism N1 Anxiety N2 Angry hostility N3 Depression N4 Self-consciousness N5 Impulsiveness N6 Vulnerability

104.96 20.27 13.38 20.22 19.11 16.89 15.08

21.72 5.42 5.68 5.45 4.92 5.55 4.91

62.54 60.38 56.55 63.84 60.93 52.66 61.87

Extraversion E1 Warmth E2 Gregariousness E3 Assertiveness E4 Activity E5 Excitement-seeking E6 Positive emotions

95.03 20.94 14.34 13.23 16.17 14.86 15.50

19.72 4.77 5.60 4.71 4.65 5.21 5.31

Openness O1 Openness to fantasy O2 Aesthetics O3 Feelings O4 Actions O5 Ideas O6 Values

117.23 17.45 19.05 21.88 16.41 19.44 23.02

Agreeableness Conscientiousness U

UU

S.D.

T

M

S.D.

T

99.07 17.68 13.45 19.36 16.82 17.76 14.00

26.03 5.79 6.86 7.13 5.79 4.05 5.50

59.29 55.30 56.80 61.77 55.38 54.40 58.54

110.04 20.63 14.80 20.61 19.88 17.90 16.22

31.23 6.86 6.48 7.19 6.83 5.63 5.36

66.33 62.35 59.58 65.70 63.25 55.90 66.46

1.11 2.74 0.72 0.39 0.81 0.56 1.71

44.41 43.80 47.29 43.54 49.00 52.67 41.84

101.90 21.68 14.08 15.10 15.36 16.54 19.15

20.17 4.30 5.33 5.48 5.48 4.66 5.84

48.21 45.41 46.44 47.62 47.14 56.83 49.35

93.52 20.51 14.76 12.10 14.75 13.91 17.49

22.45 5.31 6.07 6.47 4.06 4.86 6.58

43.97 43.80 48.92 40.82 46.34 49.33 47.32

2.42U 0.55 0.14 2.82 1.16 2.64 4.48U

19.60 6.10 6.09 4.09 4.37 5.46 3.28

52.30 51.24 50.83 52.27 49.13 50.96 54.85

126.23 19.79 20.85 24.10 17.95 20.71 22.82

18.13 5.92 4.24 3.89 4.96 5.56 4.15

57.00 55.64 53.75 57.15 52.89 53.72 54.38

109.32 16.98 20.15 20.60 13.16 18.73 19.71

17.26 6.09 5.86 5.42 3.80 5.71 4.48

48.79 50.59 54.32 50.57 41.57 49.05 47.06

49.39

8.35

48.29

49.02

7.47

47.21

45.28

10.04

42.76

3.04U

43.60

8.68

42.39

43.62

10.76

42.39

45.73

9.01

44.89

0.75

UUU

M

Schizophrenia Ž n s 41. F Ž2,134.

4.30UUU 2.31 1.23 5.73UU 12.24UUU 1.19 9.99UUU

Notes: P- 0.05, P- 0.01, P- 0.001. T scores were calculated by subtracting the normative mean score from the raw scores and divided by the normative S.D. Tests of significance were calculated on raw scores. Significant between-group differences are presented in the Results section.

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depression, HRSD scores were forced into the model first, followed by Positive Emotions scores. Results indicated that HRSD scores were a significant predictor of patient group, R 2 s 0.06; F Ž1,94. s 5.90, P- 0.02; but Positive Emotions increased significantly the incremental predictive variance of patient group when entered into the 2 model, R Chg s 0.06; FChg Ž2,93. s 6.73, P- 0.01, B s 0.26. For the facets within the O dimension, three of the six facets were significantly different, Feelings, F Ž2,134 . s 5.73, P - 0.004; Actions, F Ž2,134. s 12.24, P- 0.001; and Values, F Ž2,134. s 9.99, P- 0.001. For the Feelings facet of O, bipolar patients scored significantly higher than did schizophrenia patients. For the Actions and Values facets of O, both bipolar and unipolar patients scored significantly higher than did schizophrenic patients. Because years of education and socioeconomic status were lower in the schizophrenic patients compared to the unipolar and bipolar patients and because the dimension O has been reported to be associated with education and intelligence ŽMcCrae, 1996., we conducted two sets of regression analyses to determine if the reported differences between these patient groups could be maintained after the variance for these demographic variables were removed. In the first analysis, where the bipolar and schizophrenic patients served as the dependent variable, both years of education, R 2 s 0.21; F Ž1,74. s 7.27, P- 0.01, and socioeconomic status, R 2chg s 0.20; Fchg Ž2,73. s 9.26, P - 0.001, proved to be significant predictors to which the personality dimension O could add no significant incremental increase in predictive variance. This pattern held for each of the three facets of O that showed significance in the overall multivariate analysis. In the second set of analyses, where the unipolar and schizophrenic patients served as the dependent variable, years of education was not a significant predictor; however, socioeconomic status, R 2chg s 0.13; Fchg Ž2,101. s 9.21, P - 0.01, again proved to be a significant predictor to which the personality dimension O could add no significant incremental increase in predictive variance. This pattern also held for each of the three facets of O.

For the A dimension, unipolar patients scored significantly higher than schizophrenic patients, while there were no differences between unipolar and bipolar patients, nor were there differences between the bipolar and schizophrenic patients. Because significant differences between unipolar and schizophrenic patients were also found for age of first onset of illness, a hierarchical regression was performed. Patient group Žunipolar, schizophrenia. served as the dependent variable while A and age of first onset of illness scores served as the independent variables. In order to determine whether A contributed to the difference between the unipolar and schizophrenic patients beyond the contribution of age of first onset of illness, this variable was forced into the model first, followed by A scores. Results indicated that while age of onset of illness was a significant predictor of patient group, R 2 s 0.134; F Ž1,92. s 17.31, P- 0.001, when A was forced into the model next, it increased significantly the incremental predictive variance of patient group, 2 R Chg s 0.035; FChg Ž2,91. s 3.88, P- 0.05. 4. Discussion Two sets of conclusions can be drawn from the results of this study. First, significant difference in the personality profiles among the three groups of patients have emerged within the domain of the five-factor model of personality. Second, conclusions regarding patient characteristics relative to a non-clinical sample can be extracted by comparing patient test scores to normative data Ži.e. T-scores; Fig. 1.. As expected, no differences were found for the N domain among the three patient groups. The T-scores revealed all groups of patients to be one standard deviation higher than the normative sample reported by Costa and McCrae Ž1989, 1992b.. This finding could support the contention that N reflects a predisposition to general psychopathology. Whether or not N relates to pathogenesis Ži.e. represents a vulnerability factor for psychopathology. remains to be demonstrated. Also, the pathoplasty hypothesis, i.e. the presence of severe psychiatric disorder which increases scores on Neuroticism, is also possible. A combi-

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nation of predisposition and pathoplasty is also possible and could also be the correct interpretation of elevated Neuroticism. In other words, although we controlled for state effects in the present study by using patients not acutely ill, the extent to which previous episodes may have altered their post-morbid personality is unknown. Differences among the three patient groups were found on the E dimension; bipolar patients generated higher scores than did unipolar and schizophrenic patients. The T-scores for the bipolar patients on E are in the same range as in the normative sample, whereas unipolar and schizophrenic patients had scores below the mean of the normative sample. Among the patient groups, only the Positive Emotions facet in the E domain reached significance. High scores on the Positive Emotions facet relate to the individual experience of joy, happiness, love, excitement and optimism ŽCosta and McCrae, 1992b.. The only significant difference occurred between unipolar and bipolar patients. The T-scores for the bipolar patients were, again, in the normal range while the unipolar patients’ scores were almost one standard deviation lower. This finding replicates those of Hirschfeld et al. Ž1986a. and suggests that unipolar patients not only experience negative emotions Ži.e. high N. but are unique in their inability to experience positive affect. Similarly, relative to the normative group, the schizophrenic patients manifest a degree of anhedonia similar to that of the unipolar depressed patients. This raises the possibility that their inability to generate positive affect is an outcome of the residual ‘shut down’. The three clinical samples also differed on the O dimension. The bipolar patients had higher O scores than did the unipolar and schizophrenic patients. Significant differences were found for the Feelings, Actions and Values facets of the O dimension. While these differences were not maintained after statistically controlling for years of education and socioeconomic status, we do nonetheless speculate about these personality differences, as we believe that while personality and sociodemographic variables may be related, personality traits per se can provide important

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and meaningful insights into the characteristics of these patients. Bipolar patients had higher scores on the Feelings facet than did schizophrenic patients. High scores on the Feelings facet describe individuals who are morereceptive to their own inner feelings and emotions, who value emotion as an important part of life. Examination of T-scores for the three patient samples suggests that bipolar patients value and advert to their emotions more than do ‘normals’, while the depressed and schizophrenic patients are similar to ‘normals’ in this regard. Because bipolar disorder spans emotional extremes, between dysphoric and euphoric mood, patients suffering from this disorder may have a propensity to value and be more aware of emotions because a wide range of affects are an unavoidable phenomenological aspect of the bipolar experience. Both the unipolar and bipolar patients demonstrated higher scores when compared to the schizophrenic patients but still scored in the normal range on the O facets of Actions and Values. Individuals with low scores on the Actions facet are behaviorally less willing to try different activities, go to new places, or eatunusual foods. Compared with the normative sample, the schizophrenic group was almost one standard deviation lower on these facets while bipolar and unipolar groups scored in the normal range. The Values facet relates to the readiness to re-examine social, political, and religious values. Individuals with low scores tend to accept authority and honour tradition; as a result, they are generally conservative, regardless of political party affiliation. Both the unipolar and bipolar patients scored higher than the schizophrenia group. However, all three groups scored in the normal range. This finding is not congruent with the speculation of Berenbaum and Fujita Ž1994. that O combined with low intelligence may predispose individuals to schizophrenia. These findings, however, suggest that patients in the residual phase of schizophrenia, relative to unipolar and bipolar patients, are more dogmatic and conservative } perhaps because they experience disorganization, uncertainty, and difficulties with abstract thinking.

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Again, this may stress the pathoplastic aspect of their disorder vs. any predisposing vulnerability. There are many possible reasons why schizophrenic patients are less likely toengage in new activities and are more dogmatic while in the residual phase. For example, the lack of openness to actions and values may be related to the schizophrenic symptoms still experienced in the residual phase. Although the severity of both positive and negative symptoms was in the nonclinical range on the PANSS, these symptoms did persist, with the negative scores slightly higher than the positive scores. These negative symptoms may influence one’s ability to engage in new activities and remain dogmatic in one’s thinking. Alternatively, in trying to prevent a relapse, this clinical group may limit their experiences in an effort to control their environment. Also, the effects of neuroleptic treatment may have affected their willingness to engage in new activities. The A dimension was found to be significantly higher in the unipolar group compared to the schizophrenia sample. This dimension refers to a broad range of interpersonal orientations from compassion and cooperation at one end to competition and aggressiveness at the other. One who scores high on this domain is sympathetic to others and eager to help them, and believes that others will be equally helpful in turn. By contrast, the disagreeable or antagonistic person is egocentric, sceptical of others’ intentions, and competitive rather than cooperative. Compared to the normative sample, both the unipolar and bipolar groups were in the average range, whereas the schizophrenia group had significantly lower scores on the A dimension. The patients who formerly had experienced a schizophrenic episode were significantly less agreeable and altruistic than the unipolar group. Although the present study demonstrated personality differences among the three clinical groups, there still remain some unanswered questions. The majority of research to date has focused on differences in personality traits between unipolar and bipolar disorders; however, few have carefully examined the aspects of schizophrenia that could influence personality. There are many

factors which should be considered when examining personality and schizophrenia. One factor is the level of depression experienced in a schizophrenia sample. Bartels and Drake Ž1988. have reported that major depressive disorder can occur in the post-psychotic period of schizophrenia. Future studies should control for possible depression influences on personality scores. A second variable that should be considered is the possible differential effect of positive and negative symptoms on personality. For example, further research could examine whether different scores are generated as a result of degree of residual negative symptoms. The sample of patients in the residual phase of schizophrenia still suffered from schizophrenic symptoms. These symptoms may have a profound influence on behaviour and personality. Furthermore, because positive and negative symptoms have been found to fluctuate over time ŽWhiteford and Peabody, 1989., future research should examine personality at different time periods when symptoms change. Finally, differences also emerged in many of the demographic variables; sociocultural conditions are not an entirely independent issue in the context of examining the possible impact of a disorder. Years of education and socioeconomic status were significantly lower in the schizophrenia group compared to the two other groups. These results may well be an outcome of differences among the groups on age at onset of prior episodes. Because the age of onset was earlier in patients with schizophrenia in the residual phase, they would have had fewer opportunities to achieve higher levels of education and social status. The impact of these differences on the demographic variables and their subsequent relationship to personality are difficult to interpret. Future studies should consider matching individuals on these variables to elucidate more conclusively the relationship between the personality traits and Axis I disorders. References Bagby, R.M., Joffe, R.T., Parker, J.D., Kalemba, B.A. and Harkness, K.L. Ž1995. Major depression and the five-factor model of personality. J Pers Disord 9, 224]234.

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