Blackwell Publishing AsiaMelbourne, AustraliaPCNPsychiatry and Clinical Neurosciences1323-13162006 Folia Publishing Society2006605538545Original ArticlePersonality traits and schizophreniaA. Herrán et al.

Psychiatry and Clinical Neurosciences (2006), 60, 538–545

doi:10.1111/j.1440-1819.2006.01577.x

Regular Article

Can personality traits help us explain disability in chronic schizophrenia? ANDRÉS HERRÁN, md, DEIRDRE SIERRA-BIDDLE, md, MARIA JESÚS CUESTA, md, MARTA SANDOYA, bsn AND JOSÉ LUIS VÁZQUEZ-BARQUERO, phd Department of Psychiatry, University Hospital Marqués de Valdecilla, University of Cantabria, Santander, Spain

Abstract

Psychotic features have been considered the main determinant of psychosocial function in schizophrenia. However, other variables are likely to affect dysfunction in these patients. The authors’ hypothesis is that personality traits in outpatients with chronic schizophrenia differ from traits found in the healthy population and may be associated with disability in this disorder. A total of 62 patients with schizophrenia were evaluated with the Eysenck Personality Questionnaire (EPQ) and the Tridimensional Personality Questionnaire (TPQ). Psychotic features were measured with the help of the Positive and Negative Syndrome Scale (PANSS). Disability was assessed with the Disability Assessment Schedule (DAS). A total of 43 healthy subjects were used as controls for personality measurements. Normative data for the study population was also used to evaluate results in patients. Patients with schizophrenia had higher levels of neuroticism (median in percentile 65) and lower levels of extraversion (median in percentile 25) than the healthy population. Results of the TPQ showed higher harm avoidance and lower reward dependence levels compared to the healthy population. After multiple regression tests, negative symptoms were the strongest predictor of disability in patients with schizophrenia. Neuroticism contributed independently to the DAS overall behavior and global judgement subscales scores (more negative symptoms and higher neuroticism resulted in worse functioning), but not to the social role subscale. Outpatients with chronic schizophrenia showed high levels of neuroticism, harm avoidance, and introversion. Neuroticism significantly contributes to the long-term deficits found in patients with schizophrenia.

Key words

disability evaluation, extraversion, neuroticism, personality, psychotic disorders, schizophrenia.

INTRODUCTION The relationship between schizophrenia and personality is a relatively new area of interest. From the times of Kraepelin it has been widely thought that patients with schizophrenia suffered from a personality split, and psychotic symptoms would destroy the patient’s personality to such an extent that it would never be the same as before the psychosis. Some authors have put forward different theoretical approaches about the relationship between schizo-

Correspondence address: Andrés Herrán, Department of Psychiatry, University Hospital Marqués de Valdecilla, Avda. de Valdecilla s/n, 39008, Santander, Spain. Email: [email protected] Received 22 February 2005; revised 13 March 2006; accepted 2 April 2006.

phrenia and personality.1,2 Summarizing, three areas are considered: (i) the spectrum model (personality traits and symptoms of axis I disorder are on a continuum); (ii) the complication model (personality is a consequence of schizophrenia ‘used’ by the patient to avoid feared reactions); and (iii) the vulnerability model (personality traits predisposed to the development of schizophrenia). There are a number of studies analyzing personality in patients with schizophrenia from different points of view. Some of them have analyzed or reviewed personality traits in patients with defined schizophrenia2–8 or the axis II comorbidity of schizophrenia.9 From a different approach, others have tried to analyze the premorbid personality of patients affected by this illness.10–12 Another area of theoretical interest has been the study of personality in families of patients with schizophrenia.1,13 © 2006 The Authors Journal compilation © 2006 Folia Publishing Society

Personality traits and schizophrenia

More recent studies have explored the repercussions of personality in these patients. From a clinical point of view, some have focused on the course of schizophrenia in relation to personality variables14–16 or on their stability.17 Others explored the relationship between personality and different aspects in patients with schizophrenia, such as neuropsychological dysfunction18 or self-directed violence.19 Recent research has begun to explore the impact of personality in patients with schizophrenia in relation to measures of functioning, such as work performance20 or quality of life.21 Medical and psychiatric diagnoses alone do not fully describe the illness and its repercussions. If social functioning is a basic fact of human experience, these factors are equally basic for people suffering from schizophrenia. The authors could define social functioning or social adjustment as the ability of individuals to meet socially defined roles such as homemaker, worker, student, spouse, family member or friend. Social functioning in schizophrenia is of great relevance for different reasons; social maladjustment is usually included among the criteria for the diagnosis of schizophrenia, and impaired social functioning has been recognized as characteristic in the development of the illness. The prognosis of this disorder is also based on social disability and not only on symptoms and it would be helpful to know as many determinants of disability as is possible. However, previous studies have only included partial aspects of potentially interesting areas of study. In addition, most of these studies have included non-representative samples, and selection bias is a major concern when dealing with personality measurements. Moreover, the connections between schizophrenia and personality depend on how schizophrenia is defined, and a number of previous studies were conducted before the implementation of the current 4th edition of the Diagnostic and Statistical Manual (DSM-IV) diagnostic criteria, therefore, making interpretation of the data somewhat difficult. The authors’ aim has been to perform a comprehensive research of personality in patients suffering from chronic schizophrenia including: (i) different conceptual models of personality using self-reported measures; (ii) detailed psychopathological description with psychiatrist-administered instruments; and (iii) consequences of the illness, assessing the level of disability, and the impact of personality traits on this area. The authors focused on two well-known dimensional models of personality; the one proposed by Eysenck, using the Eysenck Personality Questionnaire (EPQ),22 and the Cloninger model, with the Tridimensional Personality Questionnaire (TPQ).23

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SUBJECTS AND METHODS In order to assess ‘normal’ personality traits, the authors used two different approaches. First, they used normative data (percentiles) of the EPQ available for the Spanish population.24 Second, since there are no normative data of the TPQ in their population, they compared dimensional measures of personality (both EPQ and TPQ) between patients and a sample of healthy control subjects.

Patients The patients of the present study have already been described elsewhere,25 therefore, only the important aspects will be summarized here. The authors included all patients diagnosed as having schizophrenia from an outpatient practice of a Mental Health Center in Santander (Northern Spain) in 1997. This practice attended nearly 47 000 people from two Primary Care Centres.26 Agreement by two senior psychiatrists was required to be eligible to enter in the study. In addition, in order to ensure the diagnoses, patients were evaluated with the Item Group Checklist (IGC) section of the Schedules for Clinical Assessment in Neuropsychiatry (SCAN),27,28 using data from clinical interviews and clinical records, and only those with a definite DSM-IV criteria of schizophrenia29 were selected. From the 81 initially selected patients, 11 were excluded as they did not meet criteria for schizophrenia (four organic psychoses, one delusional disorder, four ‘other psychotic disorders’, one schizoaffective patient, and one schizoid personality disorder). One additional patient was excluded because of comorbid mental retardation. The remaining 69 patients were asked to enter in the study, but three were illiterate, two were not available for the study, and in one patient active psychotic symptoms made it impossible to evaluate the questionnaires. After the initial evaluation, patients were asked for informed consent to participate in the study. One subject refused to give informed consent to enter in the protocol. Then, the final sample object of the study was composed by 62 outpatients with chronic schizophrenia. Complete information of personality questionnaires was not available for nine patients, but the remaining data from these patients was included in the study (EPQ data were available for 60 patients, and TPQ data for 59).

Healthy controls A total of 43 healthy subjects matched by gender (24 male, 19 female), and age (mean, 34.8 years) without © 2006 The Authors Journal compilation © 2006 Folia Publishing Society

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current or past psychiatric disorder were used as healthy controls. Psychiatric disorders were excluded by a clinical interview. No one had ever taken psychotropic drugs. They completed the two dimensional measures of personality (EPQ, TPQ). These subjects were recruited from hospital staff and through advertisements and those with university educational level were excluded in order to control for educational level of the patients.

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in harm avoidance are apprehensive, shy, fatigable and pessimistic, people scoring high in reward dependence are sentimental, socially sensitive and dedicated. Persistence reflects perseverance despite frustration and fatigue. One senior psychiatrist who provided day to day care to the patients completed the CGI, PANSS and DAS scales. The patients completed the questionnaires (EPQ, TPQ) in a room of the Mental Health Unit. All data included in the protocol were collected in a 1month period.

Clinical measurements Demographic, social, and medical history variables were assessed with a specifically created questionnaire. Clinical variables included DSM-IV schizophrenia subtype29 and the Clinical Global Impression scale (CGI).30 Psychopathology (positive symptoms, negative symptoms and general psychopathology) was assessed by the Positive and Negative Syndrome Scale (PANSS).31 Additional data regarding clinical evolution, treatment (long-acting depot neuroleptics, atypical antipsychotics) and other variables were extracted from clinical records. Chlorpromazine equivalents were calculated according to commonly used equivalent doses.32 Disability was evaluated with the help of the Disability Assessment Schedule (DAS).33 For the analysis the authors used Section 1 (dealing with overall behavior), Section 2 (an inventory of social role domains), and Section 5 (a global judgement about the level of disability). Scores range from 0 (no disability) to 5 (maximum disability).

Self-rated personality measurements In order to evaluate personality dimensions, two paperand-pencil, true–false questionnaires were used. Neuroticism and extroversion were assessed with the Eysenck Personality Questionnaire (EPQ).22 The EPQ is a 90-item self-reported inventory which generates three personality scores: extraversion, neuroticism and psychoticism, and a validity index – the lie scale. The first two dimensions have been demonstrated to be the more valid ones. Patients scoring high on neuroticism experience high levels of negative emotions, are unstable and suffer from psychological distress. Extraverted ones tend to be gregarious, sociable and uninhibited. The Tridimensional Personality Questionnaire (TPQ) is a 100-item questionnaire evaluating novelty seeking, harm avoidance, reward dependence, and persistence.23,34 Those high in novelty seeking are curious, quick-tempered, impulsive and disorderly, those high © 2006 The Authors Journal compilation © 2006 Folia Publishing Society

Analysis Data were analyzed with the statistical package SPSS 7.0 (SPSS Inc., Chicago, IL, USA). Given the ordinal nature of measurements, non-parametric tests were used. For ordinal variables (PANSS, DAS, personality scores) in function of nominal variables, Mann– Whitney U-test was used, and for comparison among ordinal variables, Spearman correlation was used. SPSS GLM General Factorial procedure was applied in order to control for other independent variables. Multivariate analysis was calculated by using multiple regression, stepwise method. Differences of less than 0.05 were considered significant.

RESULTS Sociodemographic and clinical characteristics of the sample are shown in Table 1. It is a sample of outpatients with chronic schizophrenia, with a predominance of residual subtype, and moderate severity of the illness.

Personality measurements Results of the EPQ, expressed as percentiles, are shown in Table 2. When compared with normative data, patients with schizophrenia showed higher levels of neuroticism and psychoticism, and lower levels on extraversion and lie subscales. Compared with healthy subjects, the results were comparable, with patients showing significantly higher neuroticism, psychoticism, and lower extraversion and lie (Table 3). Due to the lack of normative data of the TPQ questionnaire for the study population, the authors compared results on this test for patients and healthy controls (Table 3). Patients suffering from schizophrenia presented significant differences compared with healthy controls (higher harm avoidance, lower reward dependence and persistence). Patients with schizophrenia tended to score lower on

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Table 1. Sociodemographic and clinical variables† of the sample Gender: Men 33 (53.2%); Women 29 (46.8%) Age: 37,6 (11.4) Marital status Married: 21 (33.8%) Divorced: 4 (6.4%) Single: 37 (59.7%) Educational level Less than 7 years: 15 (24.2%) School: 28 (45.2%) High school: 17 (27.4%) University: 2 (3.2%) Schizophrenia subtype Paranoid: 21 (33.9%) Disorganized: 8 (12.9%) Undifferentiated: 9 (14.5%) Residual: 24 (38.7%) Evolution Age at the onset of schizophrenia: 24.6 (8.4) Years of evolution: 12.3 (10.0) Number of admissions in hospital: 3.4 (4.3) Treatment Antipsychotic doses:‡ 299.8 (205.7) (five patients without pharmacological treatment) Depot neuroleptics: 16 patients (28,1%) Atypical antipsychotics: 12 patients (21,1%) PANSS scale PANSS positive: 10.4 (4.5) PANSS negative: 16.3 (6.4) PANSS general: 26.1 (8.8) Total PANSS: 52.8 (15.7) †

For continuous variables, values are shown as mean (standard deviation); for nominal variables, as number (percent). ‡ As chlorpromazine equivalents (mg/day). PANSS, Positive and Negative Syndrome Scale.

Table 2. Percentiles of Eysenck Personality Questionnaire in patients with schizophrenia (n = 60)

Neuroticism Extraversion Psychoticism Lie

Mean

Median

CI (95%)

61.3 33.8 64.4 35.7

65 30 70 35

53.7–68.8 27.0–40.6 57.1–71.7 28.3–43.1

Table 4. Neuroticism was positively associated with psychoticism in patients, but not in controls. In addition, neuroticism was negatively associated with reward dependence in patients and positively in controls. Psychoticism showed a strong negative correlation with reward dependence in patients.

Association of personality measures with clinical variables Different clinical subtypes of schizophrenia did not present differences on personality measures, but disorganized patients tended to score higher on extraversion (Kruskal–Wallis test P = 0.08) and psychoticism (P = 0.07). Age at onset of schizophrenia presented a negative correlation with EPQ extraversion (rho = −0.264; n = 59; P = 0.04) and with lie scale (rho = −0.434; n = 59; P = 0.001). Years of evolution of the illness showed a negative association with novelty seeking (rho = −0.343; n = 58; P = 0.008), but this association disappeared when controlled for current age (F: 2.984; 1 d.f.; P = 0.09). Antipsychotic dosage presented a negative association with the reward dependence scale (rho = −0.352; n = 54; P = 0.009). Analyzing psychopathology by means of PANSS subscales, negative subscale negatively correlated with extraversion (rho = −0.278; n = 58; P = 0.03), and with reward dependence (rho = −0.315; n = 58; P = 0.01).

Association of personality measures with disability Dimensions included in the EPQ did not show significant relations with disability scores, but neuroticism showed a trend for a positive association with DAS’ subscales: overall behavior (rho = 0.228; n = 58; P = 0.08), social role (rho = 0.205; n = 58; P = 0.1), and global judgement (rho = 0.187; n = 58; P = 0.1). Harm avoidance showed a positive association with DAS overall behavior (rho = 0.281; n = 58; P = 0.03) and global judgement scores (rho = 0.293; n = 58; P = 0.02). In contrast, reward dependence presented negative correlations with overall behavior (rho = −0.391; n = 58; P = 0.002), social role (rho = −0.351; n = 58; P = 0.007), and global judgement score (rho = −0.349; n = 58; P = 0.007).

CI, confidence interval.

Determinants of disability novelty seeking subscale, but differences did not reach statistical significance. Significant associations between personality dimensions (those included in EPQ and TPQ) are shown in

In order to evaluate the joint effects of the clinical and personality variables on disability, a multivariate analysis was performed. In multiple regressions tests, with the DAS scores as dependent variables, and © 2006 The Authors Journal compilation © 2006 Folia Publishing Society

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Table 3. Values on Eysenck Personality Questionnaire and Tridimensional Personality Questionnaire for patients with schizophrenia and healthy controls†

Schizophrenia

Controls

P (Mann–Whitney U-test)

EPQ Neuroticism Extraversion Psychoticism Lie

(n = 60) 14.6 (5.6) 9.1 (4.3) 4.0 (3.8) 8.6 (4.8)

(n = 43) 9.3 (5.4) 11.2 (4.0) 2.1 (2.0) 12.4 (2.8)

0.000 0.02 0.001 0.000

TPQ Novelty seeking Harm avoidance Reward dependence Persistence

(n = 59) 14.0 (4.9) 18.6 (7.2) 12.5 (3.3) 4.5 (2.2)

(n = 42) 15.1 (5.4) 14.4 (5.2) 14.0 (3.6) 5.5 (1.9)

0.1 0.003 0.02 0.02

† Direct scores showed as mean (standard deviation). EPQ, Eysenck Personality Questionnaire, TPQ, Tridimensional Personality Questionnaire.

Table 4. Significant intercorrelations among personality dimensions in patients and controls

Patients with schizophrenia Neuroticism Psychoticism Harm avoidance Reward dependence Extraversion Harm avoidance Reward dependence Psychoticism Reward dependence Lie Novelty seeking Novelty seeking Harm avoidance Harm avoidance Reward dependence Healthy controls Neuroticism Harm avoidance Reward dependence Extraversion Novelty seeking Harm avoidance Reward dependence Novelty seeking Reward dependence

Rho

n

P

0.338 0.610 −0.267

60 59 59

0.008 0.000 0.04

−0.490 0.344

59 59

0.000 0.008

−0.551

59

0.000

0.388

59

0.002

−0.285

59

0.02

−0.342

59

0.08

0.478 0.347

42 42

0.001 0.02

0.475 −0.369 0.451

42 42 42

0.01 0.01 0.003

0.493

42

0.001

using clinical variables EPQ and TPQ dimensions as independent variables, the final model is presented in Table 5. In DAS overall behavior, social role, and global judgement scores, negative symptoms (PANSS © 2006 The Authors Journal compilation © 2006 Folia Publishing Society

negative subscale) were the main variable influencing disability. In the case of overall behavior and global judgement, neuroticism (as measured by the EPQ) also remained as significantly influencing disability levels. In the case of global judgement of disability, negative symptoms and neuroticism explained 44% of the variance of disability in this sample of patients with schizophrenia.

DISCUSSION The main findings of this study of patients with chronic schizophrenia were: (i) patients tend to be more neurotic and introverted than healthy subjects; (ii) Cloninger’s harm avoidance is higher, while reward dependence and persistence are lower in patients with schizophrenia; and (iii) both clinical variables and personality features contribute to explain the disability suffered by these patients. However, it must be recognized that there are some limitations in the present study. First, conclusions must be made cautiously, due to the transversal design of the study; correlations can only prove an association, not a causal relationship. Personality traits tend to be stable, but variables such as symptoms and disability are not. In addition, readers should be aware of the issue of validity of personality questionnaires, which is not well established in psychotic patients. Finally, a number of questions can be raised when evaluating the healthy population as controls for personality measurements. However, the fact that the authors found similar results when comparing patients with EPQ normative data and with EPQ scores of healthy subjects suggests that this could be viewed as an ‘adequate’ healthy sample.

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Table 5. Variables included in the regression analyses of disability SE B

β

t

Significance of t

Overall behavior PANSS negative 0.093 Neuroticism 0.044 Constant −0.774 F = 16.210; P = 0.000; Adjusted R2 = 0.352

0.018 0.020 0.426

0.570 0.211 NA

5.299 2.238 −1.818

0.000 0.029 0.75

Social role PANSS negative 0.094 Constant −0.022 F = 26.067; P = 0.000; Adjusted R2 = 0.322

0.018 0.321

0.567 NA

5.107 −0.069

0.000 0.945

Global judgement PANSS negative 0.122 Neuroticism 0.050 Constant −0.486 F = 22.961; P = 0.000; Adjusted R2 = 0.440

0.019 0.022 0.460

0.642 0.237 NA

6.418 2.364 −1.056

0.000 0.022 0.296

B

B, regression coefficient; NA, not applicable; PANSS, Positive and Negative Syndrome Scale; SE B, standard error of the regression coefficient.

Personality dimensions in schizophrenia The relationships between personality traits and schizophrenia In the present study, patients with schizophrenia showed higher levels of neuroticism and psychoticism, and lower levels on extraversion and lie subscales than normal subjects. In addition, patients presented higher harm avoidance, but lower reward dependence and persistence. Previous reports have focused mainly on neuroticism. Several studies have found that people with schizophrenia are more neurotic than controls.4,8,17 One group13 reported that people with schizophrenia show the highest values in harm avoidance in comparison to family members without any psychiatric disorder or with other psychiatric disorder or a control group. These authors have suggested that individuals with schizophrenia tend to avoid aversive stimuli, caused by experiences derived from their illness or it could be a sign of psychopathological symptoms. Berenbaum and Fujita5 summarized results of seven previous studies. In a meta-analysis they concluded that people with schizophrenia were more introverted, neurotic, and peculiar than non-scizophrenia subjects.

Personality: cause or consequence of schizophrenia? In the previously mentioned review by Berenbaum and Fujita,5 the authors mentioned two different approaches to analyze the issue of whether personality is a cause or consequence of schizophrenia: to examine

which characteristics preceded the onset of schizophrenia, and to examine which characteristics are more common in unaffected relatives of people with schizophrenia. Reviewing both, they suggest that personality traits (at least in the case of intraversion) appear to be elevated in patients prior to the onset of their psychosis, suggesting that they are associated with vulnerability of schizophrenia. In contrast, DiLalla and Gottesman1 tried to analyze the problem of personality in identical twins discordant for schizophrenia using the Multidimensional Personality Questionnaire (which measures, among others, harm avoidance). They found that the twins discordant for schizophrenia had markedly diverged from each other. Citing results of previous studies in the same sample that showed that during childhood the twins in subsequently discordant pairs did not differ in personality measures, they suggest that the observed personality differences may reflect effects of schizophrenia on normal personality. As previously stated, the authors can not assess this issue from their data given the transversal design of the study. Perhaps the conflicting results of previous studies may be the result of methodological differences (selection of patients, clinical status, personality instruments etc.), and part of the personality differences could be attributed to both hereditary factors and as a purpose to avoid punishment. Stompe et al.13 compared a schizophrenia family sample to a normal control sample and demonstrated that psychiatric diagnosis may have an influence on harm avoidance (but not on other Cloninger’s dimensions). They showed that patients with schizophrenia or schizophre© 2006 The Authors Journal compilation © 2006 Folia Publishing Society

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nia spectrum disorder try harder to avoid punishment or aversive stimuli than family members with another disorder or without any disorder. Harm avoidance and neuroticism are related concepts,23 and in the present study both patients and controls showed nearly perfect correlations between these dimensions. Interestingly, Poulton and Andrews35 demonstrated in a non-clinical population that Eysenck’ neuroticism was the best predictor of negative life events, and this personality style could perpetuate the difficulties found by psychotic patients.

The relationship between clinical features and personality traits Even though a number of reports analyzed personality traits in patients versus controls, the relations between clinical personality and clinical characteristics is a neglected area of research. The authors have not found clear associations between personality measures and clinical variables. The only exception is the weak (but significant) negative correlations of PANSS negative subscale with extraversion and reward dependence. Lysaker et al.7 found that those patients with higher levels of neuroticism had higher levels of positive and emotional discomfort symptoms. Kentros et al.17 analyzing a small number (n = 21) of patients with schizophrenia and schizoaffective patients found that negative symptoms were negatively correlated with extraversion measured with the NEO Personality Inventory (NEO PI).

Disability in schizophrenia Interest in the social outcome of schizophrenia has been developed relatively recently. Social, occupational, hospital utilization and symptoms are areas that are only modestly correlated. Initial prognostic variables continue to be more predictive of long-term outcome than cross-sectional symptom manifestations. Wieselgren et al.36 in a prospective follow up of patients with the aim of determining possible early symptoms that are predictors of social outcome, found that early negative symptoms had a predictive value for the prognosis in schizophrenia for up to 5 years. Carpenter and Strauss37 found that restricted affect at the initial evaluation had been a predictor of 5-year outcome, but it was not a significant predictor of outcome at 11 years. Jonsson and Nyman,38 trying to predict long-term outcome in schizophrenia, found that longitudinal variables indicative of ‘high-risk personality’, or duration and severity of illness were related to bad prognosis, but overt psychotic symptoms had no significant correlation with outcome. © 2006 The Authors Journal compilation © 2006 Folia Publishing Society

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Personality traits as determinants of disability in patients with schizophrenia In the current sample, neuroticism is independently associated to disability in patients with schizophrenia. In DAS overall behavior social role and global judgement scores, negative symptoms were the main variable associated with disability. In the case of overall behavior and global judgement, neuroticism also was significantly related to disability levels. As far as the authors know, there are no previous studies analyzing disability and personality traits in patients with schizophrenia. Kentros et al.21 found that a related term, quality of life, was negatively associated with neuroticism, and positively associated with extraversion using the NEO-PI. Lysaker et al.20 found that higher levels of extraversion and neuroticism predicted poorer work performance. Analyzing the concept of quality of life, Ritsner et al.39 found that psychosocial factors rather than psychopathologic symptoms affect subjective quality of life of hospitalized patients with severe mental disorders. The authors can conclude by saying that in the evaluation of disability, simple self-reported measurements of personality dimensions could help in assessing patients with schizophrenia, and these measures should be included in routine clinical assessments.

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