اسکزودیا در طیف اختلالات اسکیزوفرنی و شخصیت: نقش تفکیک

Abstract Dissociation was one of the roots of the nosopoetic construct “schizophrenia”, and a link seems to exist between psychotic and dissociative phenomena. We explored the relationship between dissociation and schizoidia as defined by the Dissociative Experiences Scale (DES) total score and the schizoidia subscale of the Munich Personality Test (MPT), respectively. The study comprised 43 outpatients diagnosed with schizophrenia spectrum disorders in remission, 47 outpatients with personality disorders and 42 non-patients. Besides the DES and the MPT, all participants also completed parts of the Symptom Checklist (SCL-90-R) and theTrauma Questionnaire (TQ). In the final multivariable logistic model, a set of five variables was identified as the strongest contributors to the occurrence of schizoida. The model included TQ broken home, MPT neuroticism, schizophrenia spectrum and personality disorder diagnoses, and SCL aggressivity; it did not include any dissociation variable. The purported relationship between dissociation and schizoidia could not be confirmed; the existence of schizophrenia-inherent dissociation appears questionable.

Introduction In spite of the recent revival of interest in dissociation, it does not play a prominent role with regard to the concepts of schizophrenia at present. Historically, however, dissociation was one of the roots of the nosopoetic construct “schizophrenia” and schizophrenic ego fragmentation can be viewed as the most pronounced form of dissociation (Scharfetter, 1998). Indeed, there seems to be a link between psychotic and dissociative phenomena: it was claimed that patients with multiple personality disorder frequently presented positive symptoms of schizophrenia such as Schneiderian first-rank symptoms (Kluft, 1987 and Ellason and Ross, 1995). In contrast, unrecognized dissociative disorders were identified in a considerable proportion of schizophrenic patients (Haugen and Castillo, 1999), who also reported more dissociative phenomena than non-clinical controls (Spitzer et al., 1997). However, the diagnostic entity of multiple personality disorder has been questioned (Aldridge-Morris, 1989) and the relationship of dissociation to schizophrenia remains unclear. There exist two diagnostic categories to classify phenomena loosely associated with schizophrenic disorders. These phenomena comprise (1) personality traits similar to fundamental symptoms of schizophrenia and often seen in patients premorbidly (Bleuler, 1972 and Angst et al., 1985) and (2) personality peculiarities often seen in non-psychotic relatives of schizophrenic patients; the corresponding categories are schizoidia and schizotypy. Kretschmer (1967) postulated as a continuum between schizothymia as a personality variant, schizoid personality disorder and schizophrenia; he defined schizoidia or “schizoid temperament” a personality type of schizophrenia spectrum disorders, a non-psychotic, transitional condition between illness and health, and he equated it with Bleuler's autism. He characterized schizoidia as a mixture of hypersensitiveness and coldness and aloofness. Bleuler (1932) called schizoid disposition a non-progressive anomaly, and according to his son (Bleuler, 1941), schizoid personality disorder (“schizoid psychopathy”) is the most frequent personality disorder seen premorbidly in patients with schizophrenia. The conception of schizoidia has been used in Europe for a long time, whereas it was not included in the Diagnostic and Statistical Manual of Mental Disorder until 1980. It was introduced as a new diagnostic category in DSM-III (American Psychiatric Association, 1980) along with the conception of schizotypy; the latter was designated to identify borderline cases (cases on “the border between neurosis and psychosis”) belonging to the schizophrenic spectrum (Spitzer et al., 1979). Whereas there is an overlap in the description of schizotypy and schizoidia–both share common features of emotional disturbance and lack of social relationships–schizotypy is also characterized by subtle cognitive-perceptual aberrations that are absent in schizoidia (American Psychiatric Association, 1994). Empirical findings suggest a good discriminant validity for both criteria sets (Bailey et al., 1993). Schizotypy has been claimed to present a higher degree of schizophrenia-relatedness than schizoidia; and a dimensional model of a spectrum of schizoidia–schizotypy–schizophrenia has been advocated (Saβ and Jünemann, 2001). If there is a relationship between dissociation and schizophrenia, then a relationship between dissociation and schizotypy and schizoidia would also be expected. A high correlation between schizotypal traits and dissociative experiences has indeed been found (Startup, 1999 and Watson, 2001); especially, detachment/depersonalization items are not clearly distinguishable from schizotypy (Watson, 2001). Much less is known about the relationship between schizoidia and dissociation. In our study on dissociation, a modest, but significant correlation (r = 0.23, P < 0.001) between dissociation and schizoidia was found ( Modestin et al., 2002). The present study approached the larger issue of the relationship between dissociation and schizophrenia indirectly, focussing on the relationship between dissociation and schizoidia. We expected that there would be a relationship between schizoidia and dissociation, but we were not sure how pronounced and how independent it would be in comparison to other variables such as personality traits, psychopathology dimensions and environmental factors. Three different groups of participants were included in the study (patients with schizophrenic disorder in remission, patients with personality disorder, and non-patients); we expected the groups to differ with regard to the degree of schizoidia.

. Results In Table 1 the three groups of participants, patients with schizophrenic disorders, patients with personality disorders, and non-patients, are compared with regard to the basic socio-demographic variables; in Table 2 they are compared with regard to the DES, MPT and SCL-90 scores and TQ trauma experiences. On the whole, socio-demographic characteristics of the patients with schizophrenia are different from those of the other two groups. Considering the scale ratings, non-patients are different, whereas there is a similarity between the two groups of patients. Patients with personality disorders less frequently reported broken homes before the age of 18; otherwise, no significant differences were found between the groups in the frequency of traumatic experiences. Table 2. Comparison of the three study groups with regard to scale ratings Schizophrenic disorders, n1 = 43 (100) Personality disorders, n2 = 47 (100) Non-patients, n3 = 42 (100) Significance χ2(2)/F⁎ P DES total score: Mean ± S.D. 9.9 ± 6.8 11.5 ± 11.8 7.6 ± 6.3 ns Absorption/imagination: Mean ± S.D. 12.8 ± 7.8 14.9 ± 15.4 11.1 ± 8.2 ns Dissociative states: Mean ± S.D. 3.5 ± 5.7 1.6 ± 2.3 1.8 ± 3.9 ns Depersonalization/derealization: Mean ± S.D. 9.0 ± 6.9 8.9 ± 12.9 3.6 ± 4.4a 5.25⁎ 0.006 MPT isolation tendency: Mean ± S.D. 6.4 ± 2.5 6.1 ± 2.2 4.5 ± 2.6a 7.93⁎ 0.0006⁎⁎ Esoteric tendencies: Mean ± S.D. 3.5 ± 2.0 2.8 ± 2.0 2.0 ± 1.6d 6.70⁎ 0.002⁎⁎ Schizoidia: Mean ± S.D. 9.9 ± 4.1 8.9 ± 3.0 6.5 ± 3.1a 11.26⁎ < 0.0001⁎⁎ Extraversion: Mean ± S.D. 11.2 ± 5.4 11.5 ± 5.8 12.0 ± 4.4 ns Neuroticism: Mean ± S.D. 11.6 ± 4.7 12.5 ± 5.7 9.4 ± 5.3c 3.81⁎ 0.025 Frustration tolerance: Mean ± S.D. 7.5 ± 3.5 6.7 ± 3.5 6.4 ± 2.3 ns Rigidity: Mean ± S.D. 9.6 ± 4.3b 7.8 ± 3.0 8.0 ± 3.0 3.51⁎ 0.033 Social norms orientation: Mean ± S.D. 13.8 ± 2.5 14.4 ± 2.4 13.1 ± 3.2 ns Motivation: Mean ± S.D. 6.9 ± 0.3 6.9 ± 0.4 7.0 ± 0.2 ns SCL-90 social insecurity: Mean ± S.D. 64.4 ± 10.6 67.7 ± 9.7 60.5 ± 9.4c 5.89⁎ 0.004 Aggressivity: Mean ± S.D. 55.5 ± 10.6 60.3 ± 14.2 55.6 ± 12.3 ns Paranoid thinking: Mean ± S.D. 63.7 ± 10.7 67.2 ± 9.9 62.1 ± 11.3 ns Psychoticism: Mean ± S.D. 66.5 ± 10.3 67.0 ± 10.5 57.0 ± 12.5a 11.04⁎ < 0.0001⁎⁎ TQ trauma experiences Broken home 11 (26) 0 (0)e 6 (14) 13.21 < 0.0014⁎⁎ Dysfunctional family 12 (28) 16 (34) 11 (26) ns Family violence 9 (21) 11 (23) 10 (24) ns Child sexual abuse 10 (23) 17 (36) 10 (24) ns Severe child sexual abuse 8 (19) 11 (23) 6 (14) ns Adult sexual abuse 9 (21) 19 (40) 10 (24) ns Percentages are given in parentheses. an3 < n1,n2; bn1 > n2; cn3 < n2; dn3 < n1; en2 < n1,n3. ⁎Indicates F-value. ⁎⁎Remains significant after Bonferroni correction (P < 0.0022). Table options The results of the logistic regressions are presented in Table 3. The upper part presents significant results of the bivariate logistic regressions (including the non-significant variable “Personality disorder” for the sake of completeness), and the lower part shows the result of the multivariable logistic regression analysis. The classification into the low and high MPT schizoidia group (according to median) served as a dependent variable. Odds ratios are indicated, enabling a more precise and comparable statement on the influence of the independent variables on schizoidia. Regarding continuous independent variables, odds ratios indicate the probability of an increase or a decrease of schizoidia when there is a one standard deviation increase in the independent variable. The multivariable analysis yielded a model of five independent variables that best explain the dependent variable schizoidia. Table 3. Results of logistic regression analyses Variable Odds ratio z P > |z| 95% confidence interval DES total 2.66 3.34 0.001 1.50–4.73 DES absorption/imagination 2.20 3.10 0.002 1.34–3.63 DES dissociative states 2.87 3.17 0.002 1.49–5.50 DES depersonalization/derealization 2.31 2.96 0.003 1.33–4.03 MPT motivation 0.64 1.99 0.047 0.41–0.99 MPT social norms orientation 0.58 2.78 0.006 0.40–0.85 MPT neuroticism 3.41 5.09 0.000 2.13–5.48 SCL psychoticism 2.10 4.14 0.000 1.48–2.99 SCL paranoid thinking 1.62 2.76 0.006 1.15–2.29 SCL aggressivity 1.96 4.07 0.000 1.42–2.72 SCL social insecurity 2.06 3.65 0.000 1.40–3.03 Dysfunctional family 2.26 2.08 0.038 1.05–4.90 Broken home 5.65 2.61 0.009 1.54–20.74 Upward social mobility 0.24 3.10 0.002 0.10–0.59 Schizophrenia spectrum disorders 2.16 2.03 0.043 1.03–4.57 Personality disorders 1.82 1.63 0.103 0.88–3.75 Non-patients 0.23 3.61 0.001 0.10–0.51 Broken home 3.50 1.68 0.094 0.81–15.17 MPT neuroticism 2.34 3.22 0.001 1.39–3.93 Schizophrenia spectrum disordera 4.55 2.61 0.009 1.46–14.20 Personality disordera 3.94 2.40 0.016 1.28–12.10 SCL aggressivity 1.45 1.82 0.068 0.97–2.16 Upper part: bivariate logistic regressions; survey of significant differences. Lower part: result of the multivariable logistic regression analysis. Classification into low or high MPT schizoidia group = dependent variable. OR related to 1 S.D. increase in independent continuous variables. a Non-patient group = reference group. Table options It should be noted that in bivariate logistic regressions the DES total score and all three DES subscale scores indicated a substantial increase of MPT schizoidia, most of them on the DES dissociative states subscale. However, none of these variables appeared in the multivariable model having been confounded with the variables that remained in the final model. We explored the relationship of DES total score to the model variables with the help of multiple linear regressions where the DES total score was a dependent variable. MPT neuroticism and SCL aggressivity explained 32.4% of DES total variance, and this figure remained unchanged after consideration of the other model variables.