Bizarre delusions and DSM-IV schizophrenia

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1 Psychiatry and Clinical Neurosciences (2002), 56, Regular Article Bizarre delusions and DSM-IV schizophrenia MAKOTO NAKAYA, md, phd, 1 KATSUNORI KUSUMOTO, md, phd, 2 TAKAYUKI OKADA, md, phd 3 AND KENICHI OHMORI, md, phd 1 1 Department of Psychiatry, Dokkyo University School of Medicine, Kitakobayashi, Mibu,Tochigi, 2 Medical Research Center, International University of Health and Welfare, Kitakanamaru, Ohtawara and 3 Medical Research Institute,Tokyo Medical and Dental University,Yushima,Tokyo, Japan Abstract The present study investigated whether schizophrenia patients with and without DSM-IV bizarre delusions, categorized as bizarre delusions of Schneiderian first rank symptoms (SBD) and as non-schneiderian bizarre delusions (non-sbd), differed on demographic or clinical features, in view of the weight given to bizarre delusions in the diagnosis of schizophrenia. One hundred and twenty-nine in-patients with schizophrenia were assessed systematically for both types of bizarre delusions on the five domains of psychopathology of the Positive and Negative Syndrome Scale (PANSS; delusions/hallucinations, thought disorder/disorganization, excitement, negative symptoms and depressive symptoms) and for extrapyramidal side-effects. Inter-rater reliabilities for SBD and non-sbd were assessed and were exceptionally high (kappa value 0.85 and 0.92, respectively). Neither SBD nor non-sbd were associated with any demographic or non-panss clinical characteristics tested. However, the presence of non-sbd was significantly associated with more severe psychopathology in all five domains of the PANSS, whereas the presence of SBD was significantly associated with more severe psychopathology in three domains only: delusions/hallucinations, thought disorder/disorganization and depressive symptoms. However, patients with only SBD did not differ from patients with only non-sbd on any demographic or clinical variables, including five psychopathological domains. These findings suggest that, despite showing more severe symptoms, patients with DSM-IV bizarre delusions do not constitute a clinically distinguishable subgroup. Key words bizarre delusion, negative symptom, positive symptom, schizophrenia. INTRODUCTION Schizophrenia, as a diagnosed category, is heterogeneous, allowing considerable variations in symptoms, premorbid history, clinical course, prognosis and pathophysiology, and the essential biological pathology of schizophrenia is still only partially understood. Most recent diagnostic systems, including the DSM- IIIR, 1 DSM-IV 2 and ICD-10, 3 give special significance to bizarre delusions as diagnostic criteria for schizophrenia, but this arrangement is lacking in empiric Correspondence address: Makoto Nakaya, Department of Psychiatry, Dokkyo University School of Medicine, 880 Kitakobayashi, Mibu, Tochigi , Japan. m-nakaya@dokkyomed.ac.jp Received 11 May 2001; revised 26 October 2001; accepted 10 December validation, being heavily dependent on historical clinical research, especially Schneider s concept of first rank symptoms (FRS). 4 Schneider s FRS included delusions of passivity (thought withdrawal, thought insertion, controlled feelings, controlled impulses, controlled volitional acts and somatic passivity), thought broadcasting and delusional perception. The DSM-IIIR defines bizarre delusions broadly as phenomena... that in the person s culture would be regarded as totally implausible, giving examples such as thought broadcasting and being controlled by a dead person, both of which appear as Schneiderian bizarre delusions (SBD), and it remains to be clarified to what extent DSM-IIIR bizarre delusions and SBD are overlapping concepts. The definition of bizarre delusions in DSM-IV 2 includes not only SBD, but also non-sbd; for example, the delusion that... a stranger has removed his or her internal organs and has replaced

2 392 M. Nakaya et al. them with someone else s organs without leaving any wounds or scars. The ICD-10 3 categorizes delusions such as being able to control the weather or being in communication with aliens from another world also as bizarre delusions. The DSM-IIIR, DSM-IV and ICD-10 criteria determine that the presence of a bizarre delusion as a single psychotic symptom suffices to meet the symptom criterion for the diagnosis of schizophrenia. The reliability of DSM-IIIR bizarre delusions has been reported as low in three studies (k<0.40) 5 7 while reaching acceptable levels (k b3 0.64) in two studies. 8,9 The unclear definition of bizarre delusions in DSM-IIIR may account for this discrepancy. The present study examined the inter-rater reliability of bizarre delusions of DSM-IV and whether schizophrenia patients with and without DSM-IV bizarre delusions differed on demographic or clinical features. METHODS Subjects The subjects were 137 patients with schizophrenia consecutively admitted to a long-stay psychiatric unit. All patients had been diagnosed with schizophrenia by clinicians using the DSM-IV criteria. For each subject, the diagnosis of schizophrenia was confirmed independently by both clinical chart review and interviews conducted by two of the research psychiatrists (MN and KK). Patients with organic brain syndrome, mental retardation, hard drug or alcohol abuse and/or aged over 65 years were excluded from the study, as were eight patients who declined to participate in the study. Data was analyzed from the remaining 129 patients, all of whom gave written informed consent to participate. The patient sample included chronic inpatients at various stages after an acute flare-up (n = 15) and in the stable stages of the illness (n = 114). All were undergoing neuroleptic treatment at the time of the study. Biperiden or trihexyphenidyl was administered routinely as an antiparkinsonian treatment. The representation of subtypes of schizophrenia, as defined by the DSM-IV criteria, was 3% catatonic, 15% disorganized, 62% paranoid, 13% undifferentiated and 7% residual. Procedure Schizophrenic symptoms were assessed using the Positive and Negative Syndrome Scale (PANSS). 10 In a previous study on another patient population, interrater reliability on the PANSS items ranged from 0.65 to and this was not tested in the present study. The presence of SBD and non-sbd was assessed, based on both the PANSS interviews and the reviews of clinical charts describing the contents of the patients delusions. Two investigators (MN and KK) conducted joint practice interviews before the study commenced and joint ratings (total 45) were made at intervals throughout the study to monitor the interinvestigator agreement on the presence/absence of bizarre delusions. The Simpson and Angus Extrapyramidal Rating Scale (EPRS) 12 and the Abnormal Involuntary Movement Scale (AIMS) 13 were also administered. For each patient, the assessment battery was administered in the course of 1 week. Statistical analyses Subjects were divided into four groups, as shown in Table 1. There were 36 patients (28%) with both SBD and non-sbd and 36 patients (28%) with SBD only; there were 15 patients (12%) with non-sbd only and 42 patients (33%) with neither SBD nor non-sbd. For statistical analysis, items from the PANSS were grouped into the five domains or factors identified in previous investigations of the latent structures underlying schizophrenic symptoms: 14,15 delusions/hallucinations (delusion, hallucinatory behavior, grandiosity, suspiciousness and unusual thought content: PANSS item numbers P1, P3, P5, P6 and G9, respectively); thought disorder/disorganization (conceptual disorganization, difficulty in abstract thinking and poor attention; PANSS item numbers P2, N5 and G11); excitement (excitement, hostility, tension and uncooperativeness; PANSS item numbers P4, P7, G4 and G8); negative symptoms (blunted affect, emotional withdrawal, poor rapport, passive/apathetic social withdrawal and lack of spontaneity and flow of conversation; PANSS item numbers N1, N2, N3, N4 and N6); and depressive symptoms (somatic concern, anxiety, guilt feelings and depression; PANSS item numbers G1, G2, G3 and G6). Marital status and gender in the four groups were compared using the Chi-squared test, while sociodemographic (age and education) and clinical characteristics (age at onset, duration of illness, number of hospitalizations, total duration of hospitalization and extrapyramidal sideeffects) were compared using a two-way analysis of variance (anova). A multivariate analysis of variance (manova) was performed to assess the overall associations of bizarre delusions of both types with symptom profiles and a two-way anova was then used to test individual associations between the delusional factors and the symptom domains. The significance level was set at a=0.05.

3 Table 1. Demographic and clinical characteristics of 129 schizophrenic patients with and without bizarre delusions SBD present SBD absent SBD+ non-sbd Non-SBD only Non-SBD only Neither Two-way anova (n = 36) (n = 36) (n = 15) (n = 42) SBD F Non-SBD F Interaction F Age (years) 44.6 ± ± ± ± (NS) 1.09 (NS) 2.68 (NS) Education (years) 10.7 ± ± ± ± (NS) 0.70 (NS) 0.02 (NS) Age at onset (years) 24.5 ± ± ± ± (NS) 0.35 (NS) 1.00 (NS) Months since onset ± ± ± ± (NS) 0.98 (NS) 0.81 (NS) No. hospitalizations 3.9 (3.3) 4.4 (4.1) 3.3 (2.4) 3.4 (2.3) 1.28 (NS) 1.29 (NS) 0.01 (NS) Duration of hospitalization (months) ± ± ± ± (NS) 2.17 (NS) 0.47 (NS) EPRS 2.5 ± ± ± ± (NS) 0.30 (NS) 0.00 (NS) AIMS 0.8 ± ± ± ± (NS) 0.74 (NS) 0.67 (NS) PANSS Delusion/hallucination 18.1 ± ± ± ± (P < 0.001) (P < 0.001) 0.04 (NS) Thought disorder/disorganization 10.1 ± ± ± ± (P < 0.05) 9.13 (P < 0.001) 1.02 (NS) Excitement 9.5 ± ± ± ± (NS) 3.31 (P < 0.05) 2.77 (NS) Negative symptom 15.8 ± ± ± ± (NS) 4.11 (P < 0.05) 0.03 (NS) Depressive symptom 9.1 ± ± ± ± (P < 0.05) 4.27 (P < 0.05) 0.26 (NS) Chi-squared (d.f. = 3) Gender (% males) 19 ± ± 44 8 ± ± (NS) Marital status (% single) 25 ± 69% 20 ± 56% 11 ± 73% 31 ± 74% 3.40 (NS) Data are the mean ± SD. SBD, Schneiderian Bizarre Delusion; EPRS, Simpson and Angus Extrapyramidal Rating Scale; AIMS, Abnormal Involuntary Movement Scale; PANSS, Positive and Negative Syndrome Scale. Bizarre delusions 393

4 394 M. Nakaya et al. One-way anova was used to test for differences between the SBD only and non-sbd only groups on all demographic and clinical features individually. RESULTS The inter-rater reliability for the presence/absence of SBD was 0.85 (Cohen s kappa) and for non-sbd it was Table 1 presents mean (± SD) scores for each item in each of the four groups, together with the results of the two-way anova for all items except gender and marital status, for which the Chi-squared test was used. Patients did not differ significantly in gender or marital status in the four groups. Similarly, the twoway anova showed no significant differences in the four groups on age, educational level, age at onset, illness duration, number and duration of hospitalizations or extrapyramidal side-effects. However, the manova indicated significant differences in the patients symptom profiles across the groups (Wilks l =0.538, F = 3.13, P < for SBD; Wilks l = 0.465, F = 3.77, P < for non-sbd). The subsequent two-way anova on single domains indicated that non-sbd scores were significantly associated with scores on all five domains of psychopathology from the PANSS, whereas SBD scores were significantly related only to delusions/hallucinations, thought disorder/disorganization and depressive symptoms. Patients with SBD only and non-sbd only did not differ in gender or marital status (Chi-squared = 1.78 and 1.40, respectively; NS). One-way anova indicated no significant differences between these two groups on any demographic or clinical features (age, educational level, age at onset, illness duration, number and duration of hospitalizations, EPRS, AIMS the or five domains of psychopathology; F values ranged from 0.02 to 1.77; NS). DISCUSSION The unclear definition of bizarre delusions in DSM- IIIR and the fact that it is unclear whether bizarre delusions are simply equivalent to SBD in the DSM-IIIR may account for the discrepancy between reported reliabilities of bizarre delusions. 5 9 Tanenberg-Karant et al. 16 assessed DSM-IIIR bizarre delusions, distinguishing between SBD and non-sbd and reported kappa values of 0.86 for SBD and 0.68 for non-sbd. However, Junginger et al. 17 reported kappa values of 0.76 for SBD and 0.45 for non-sbd. In the present study, the reliabilities for both SBD and non-sbd were very high (kappa values 0.85), suggesting that the concept of bizarre delusions in DSM-IV and ICD-10 has a high reliability. The prevalence rate of bizarre delusions in the present study (67%) was lower than that in the study of Goldman et al. (79%), 9 while the prevalence rate of non-sbd was much higher in the present study (40%) than in the study of Tanenberg-Karant et al. 16 (5%). Goldman et al. did not report non-sbd rates because they did not distinguish between SBD and non-sbd in their study. The schizophrenia subgroup in the study of Tanenberg-Karant et al. 16 included only first-admission in-patients, whereas the subjects in the present study were chronic in-patients, with a mean number of hospitalizations of more than three. This difference may be responsible for the discrepancy in the prevalence rates of non-sbd. In the present study, neither SBD nor non-sbd were associated with the demographic and clinical characteristics investigated (age, gender, marital status, educational level, age at onset, illness duration, number and duration of hospitalizations or extrapyramidal side-effects). This is in close agreement with the findings of previous studies in which SBD has not been significantly associated with these demographic and clinical variables. 16,18,19 However, the presence of non-sbd was significantly associated with more severe psychopathology in all five domains of the PANSS and the presence of SBD was associated with more severe psychopathology in three domains (delusions/hallucinations, thought disorder/disorganization and depressive symptoms). This finding of a differential effect of SBD and non-sbd delusions appears to be contradicted by the finding of no differences of association between the SBD only and the non-sbd only groups and their difference in capture of symptoms would appear to be small. These findings suggest that, beyond showing more severe symptoms, patients with DSM-IV bizarre delusions do not constitute a clinically distinguishable subgroup. REFERENCES 1. American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 3rd edn. American Psychiatric Association, Washington DC, American Psychiatric Association. Diagnostic and Statistical Manual of Mental Disorders, 4th edn. American Psychiatric Association, Washington DC, World Health Organization. The ICD-10 Classification of Mental and Behavioural Disorders. World Health Organization, Geneva, Schneider K. Klinische Psychopathologie. II Auflage. George Thieme, Stuttgart, 1976.

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