Positive and negative symptoms in schizophrenia: where are the data?

Factor structure of the BPRS in deaf people with schizophrenia: correlates to language and thought

INTRODUCTION

There has been a relative lack of research on deaf people with schizophrenia, and no data exist regarding symptom structure in this population. Thus, we determined the factor structure of the 24-item Brief Psychiatric Rating Scale (BPRS) in deaf (n = 34) and hearing (n = 31) people with schizophrenia and compared it to a standard four-factor solution.

METHOD

An obliquely rotated factor analysis produced a solution for the BPRS that resembled others in the literature. Symptom clusters were additionally compared to cognitive and social-cognitive abilities.

RESULTS

Activity and disorganised symptoms were the most consistent correlates of visual- and thought and language-related skills for deaf and hearing subjects respectively. Affective symptoms and facial affect processing were positively correlated among deaf but not hearing subjects.

CONCLUSIONS

The data suggest that current symptom models of schizophrenia are valid in both hearing and deaf patients. However, relations between symptoms, cognition, and outcome from the general (hearing) literature cannot be generalised to deaf patients. Findings are broadly consistent with pathophysiologic models of schizophrenia suggesting a fundamental cortical processing algorithm operating across several domains of neural activity including vision, and thought and language. Support is provided for recent advances in social-cognitive interventions for people with schizophrenia.

Dimensional structure of psychotic symptoms: an item-level analysis of SAPS and SANS symptoms in psychotic disorders

The factor structure of psychotic symptoms as assessed by means of the Scales for the Assessment of Positive and Negative Symptoms (SAPS and SANS) was examined in a sample of 660 psychotic inpatients. Analyses were conducted at item-level. Principal-component analysis (PCA) was used to extract factors, the OBLIMIN procedure to rotate factors, and the eigen value greater-than-one criterion to determine the number of factors. PCA resulted in 11 interpretable factors explaining 64% of the total variance: poverty of affect/speech, thought disorder/inappropriate affect, bizarre delusions, social dysfunction, other delusions, paranoid delusions, bizarre behavior, nonauditory hallucinations, auditory hallucinations, manic thought disorder, and attention. Many of the factors were significantly intercorrelated. A second-order PCA resulted in four second-order factors, the first three roughly corresponding to the well-known psychosis, disorganization and negative dimensions. It is concluded that the factor structure of psychotic symptoms is more complex than is generally acknowledged, and that the dimensions of psychosis, disorganization and negative represent second-order dimensions. The subscale composition of the SAPS and SANS was not supported.

Neurocognitive deficits and neurological signs in schizophrenia

OBJECTIVE

This is a comprehensive study designed to examine the association between specific clusters of neurological abnormalities and several clinically relevant aspects of schizophrenia such as positive and negative symptoms, neurocognitive deficits and psychosocial performance.

METHODS

Thirty-seven clinically stable schizophrenic (DSM-III-R) patients maintained on antipsychotic medication were comprehensively examined and Convit's Quantified Neurologic Scale (QNS) was completed. In addition, patients' psychopathology was rated on the Positive and Negative Syndromes Scale (PANSS); psychosocial performance was rated on the Global Scale of Adaptive Functioning (GAF) and the Social Performance Schedule (SPS); and neurocognitive deficits were measured with a computer-assisted neurocognitive test battery, COGLAB. The association between these factors was determined using Pearson's correlation coefficients.

RESULTS

Frontal and soft neurological scores on the QNS correlated significantly with negative syndrome scores (r = 0.45-0.51, p < 0.05) and general psychopathology scores (r = 0.46-0.49, p < 0.02) on PANSS; poor psychosocial performance on GAF (r = 0.43-0.56, p < 0.02) and SPS (r = 0.37-0.54, p < 0.007); and performance on the span of apprehension (r = 0.48-0.67, p < 0.0001), backward masking (r = 0.34-0.54, p < 0.01) and Wisconsin card sorting (r = 0.48-0.67, p < 0.001) tasks.

CONCLUSION

Frontal and soft neurological signs in schizophrenic patients are associated with prominent negative symptoms, relatively poor psychosocial performance and significantly more cognitive impairment. Past research has associated soft neurological signs, cognitive impairment and structural brain abnormalities with poor outcome and prognosis in patients with schizophrenia.

Principal components and further possibilities with the PANSS

At the end of the last century, Hughlings-Jackson suggested that positive and negative syndromes should be kept apart in psychotic disorders. When the concepts of dementia praecox and schizophrenia were introduced by Kraepelin and Bleuler, emphasis was laid on the negative symptoms, regarded as fundamental. After the introduction of the "first rank symptoms" by Schneider emphasis switched to the positive symptoms in schizophrenia and these symptoms were included in most diagnostic criteria. In the 1980s Andreasen and Crow suggested a dichotomy into positive and negative syndromes in schizophrenia. Kay and co-workers introduced a Positive And Negative Syndrome Scale (PANSS) for schizophrenia. In the original studies satisfactory construct validity and inter-rater reliability were demonstrated. However, in studies outside the USA a high construct validity was found for the negative scales but not for the positive and general psychopathology scales. Furthermore, the inter-rater reliability of the negative scale was a problem. After introduction of the Structured Clinical Interview for the PANSS (SCI-PANSS) the inter-rater reliability increased for all three scales. In an early study Kay and Sevy found seven factors in a principal component analysis of the PANSS and suggested a four factor pyramidical model. Later principal component analyses by Lepine, Peralta et al. and Kawasaki et al. suggested that the four factor model was an oversimplification and Lindström and von Knorring suggested a five factor pyramidical model. A similar model was later suggested by Bell et al. after a reanalysis of the original series of Kay and Sevy.(ABSTRACT TRUNCATED AT 250 WORDS)

Primary enduring negative symptoms in schizophrenia and major depression

Primary enduring negative symptoms (PENS) were studied in 26 patients with DSM-III-R schizophrenia and in 94 patients with unipolar major depressive episodes 5 years after the index episode. PENS were assessed with the Schedule for Deficit Syndrome (SDS). Negative symptoms were also assessed with the Scale for Assessment of Negative Symptoms (SANS) and subclassified into primary and secondary according to the SDS. The frequency of PENS did not differ significantly between schizophrenics and non-schizophrenic patients. Enduring negative symptoms (regardless of whether primary or not) were more frequently observed in schizophrenia (65% according to the SDS, and 88% according to the SANS) than in patients who had major depressive episodes (29% according to the SDS and 32% according to the SANS). By applying the SDS criteria for PENS, their frequency decreased in a manner which would probably affect the availability of patients samples for testing antinegative drugs. The results suggest that neither the negative symptomatology nor the primary enduring subtype ("deficit") is specific for schizophrenia. This finding might imply potential advantages of non-nosological, functional approaches for research into PENS.

Positive and negative symptoms/syndromes in schizophrenia: reliability and validity of different diagnostic systems

The paper explores the reliability, concurrent validity and overlap of some positive/negative symptom rating scales and typological criteria in 100 schizophrenic patients. Rating scales include Andreasen's Scales for the Assessment of Positive and Negative Symptoms, Abrams and Taylor's Scale for Emotional Blunting, and Kay's Positive and Negative Syndrome Scale. Criteria for categorizing individual patients include Andreasen's and Kay's criteria for positive and negative types of schizophrenia as well as Carpenter's criteria for the deficit syndrome. The correlations among positive as well as among negative scales were high. The agreement among criteria tended to be lower. Both positive scales showed low internal consistency. Kay's negative scale had the greatest internal consistency, which suggests that it is measuring a homogeneous syndrome. All negative symptom scales and categorical syndromes identified a group of patients who were single and exhibited schizoid or schizotypal pre-morbid personality disorders, poor premorbid sexual/social adjustment, poor response to neuroleptics and poor prognosis.

An empirical analysis of latent structures underlying schizophrenic symptoms: a four-syndrome model

Various models of schizophrenia have postulated two syndromes (i.e., positive and negative), although other exploratory factor analyses have suggested a disorganization syndrome. We conducted a confirmatory factor analysis (CFA) on Schedule for the Assessment of Positive Symptoms (SAPS) and Schedule for the Assessment of Negative Symptoms (SANS) items and subscales to assess the latent structure of symptoms reflecting underlying pathological processes. The sample included 253 DSM-IIIR schizophrenic inpatients. Fourteen different models with one, two, three, or four syndromes were compared using CFA for "goodness of fit." The three-syndrome models displayed better fitness than any of the one- or two-syndrome models. All of the three-syndrome models shared the positive and negative dimensions; the third dimension in these three-syndrome models was either the disorganization or Strauss' relational dimensions. In the reported data, a four-syndrome model, including positive, disorganization, negative, and relational dimensions, showed excellent fitness. Despite its limitations, this study suggests the need to explore the validity of a four-syndrome model. The positive-negative model fits poorly with the data.

Psychometric properties of the positive and negative syndrome scale (PANSS) in schizophrenia

We analyzed the psychometric properties of the Positive and Negative Syndrome Scale (PANSS) in a sample of 100 DSM-III-R schizophrenic patients. Our findings coincided with the results of Kay's group in the following points: (1) the PANSS scores were normally distributed; (2) the positive and negative scales showed good interrater reliability; (3) positive and negative syndromes are independent constructs; (4) the positive and negative scales held a high concurrent validity in relation to the Scale for the Assessment of Positive Symptoms and the Scale for the Assessment of Negative Symptoms; and (5) although positive and negative syndromes showed factorial validity, they were not sufficient to account for the whole of the schizophrenic symptoms. Unlike Kay's group, we found a modest internal consistency of the positive scale, indicating that it is composed of several independent components. The data suggest that the distinction between positive and negative symptoms is an oversimplification, and that schizophrenic symptoms can be better conceptualized as composed of, at least three dimensional syndromes: positive, disorganized, and negative.

Influence of patient caregivers on course of patient illness: "expressed emotion" and alternative measures

The influence of the quality of care that patients receive during the course of their illness has been the subject of special scrutiny in the area of mental health. The concept of "expressed emotion" (EE) evolved in an effort to understand the impact of family and social environment on the vulnerability to relapse of schizophrenic patients. A semistructured interview, the Camberwell Family Interview, was developed to assess expressed emotion. This article examines the historical context, generalizability, methodological strengths and limitations of the construct of EE and the Camberwell Family Interview, as well as the nature and effects of treatment intervention programs designed to neutralize adverse effects of patient caretaker attitudes.

Positive, negative, and disorganisation factors from the Schedule for Affective Disorders and Schizophrenia and the Present State Examination. A three-factor solution

The use of items from the Schedule for Affective Disorders and Schizophrenia and from the Present State Examination scales for assessing positive and negative symptoms in schizophrenia was examined using factor analysis. The factorial structure of the items which putatively assess positive and negative symptoms was examined. A three-factor solution was obtained with factors identified as: a negative symptom factor (factor 1); a positive symptom factor (factor 2); a 'disorganisation' factor (factor 3), consisting primarily of items related to disordered thinking. A solution which was highly similar in important loadings was obtained with an independent sample of patients. High correlations of the rotated factors with the external criteria supported the interpretations of the factors. The results indicate that symptoms generally classified as negative or positive are factorially independent. Furthermore, a disorganisation factor, consisting of items previously included in positive and negative symptoms factors, is necessary for a full representation of the factor structure.

A multidimensional (pharmacokinetic and clinical-biological) approach to neuroleptic response in schizophrenia. With particular reference to drug resistance

Despite the undisputable effectiveness of the available neuroleptic medications (NDs), short and long term outcome of schizophrenic disorders is often unsatisfactory and drug resistance phenomena are not uncommon. The causes of variability in the response seem to be primarily due to the heterogeneity of schizophrenic syndromes in terms of clinical history, symptoms, and biological patterns. The high non-compliance rate is an important source of therapeutic failure particularly during long-term treatment. The lacking or poor response to NDs can be linked to peculiar drug disposition patterns, which lead generally to inadequate plasma concentrations (too low or too high). To deal with pharmacokinetic aspects two main topics are discussed in this paper: (A) the interindividual differences in bioavailability and metabolism and (B) the plasma level-clinical response relationship. The knowledge of these aspects can significantly contribute to reducing some pseudo-drug resistance phenomena. Moreover, the need to combine these data with the new acquisitions on the pathophysiology of these disorders is emphasized, to deal properly with the complexity of drug response mechanisms during therapy with NDs. New heuristic paradigms for schizophrenic disorders, stemming from the evidences of their heterogeneity, in terms of clinical course, outcome and biological findings, should be considered in relation to response. Accordingly, the concept of 'therapeutic window' (as conceived in the '70s) for NDs (as for antidepressants) needs to be reexamined in relation to recent clinical, neurochemical and neuromorphological data. Finally, the indications for NDs monitoring (particularly for drugs like haloperidol and fluphenazine) are reported, suggesting that a multidimensional operational strategy could be particularly suitable to deal with drug resistance problems.