Academic journal article Indian Journal of Psychiatry

Factor Analysis of Positive and Negative Syndrome Scale in Schizophrenia: An Exploratory Study

Academic journal article Indian Journal of Psychiatry

Factor Analysis of Positive and Negative Syndrome Scale in Schizophrenia: An Exploratory Study

Article excerpt

Byline: Ajay. Kumar, C. R. J.. Khess

Background: Controversy persists with regard to how best we can categorize symptomatic dimension of Schizophrenia. Aim of the study was to compute factorial dimensions in Indian subset of schizophrenic patients and to compare them with five factor pentagonal model extracted in western studies. Materials and Methods: 150 inpatients of Schizophrenia with acute exacerbation were subjected to PANSS rating within one week of admission and statistical calculation done based on exploratory factor analysis. Results: Five factors namely negative, autistic, activation, positive and depression were extracted wherein negative factors showed highest percentage of total variance supporting five factor modal of western literature Conclusion: A consensus is gradually emerging regarding symptomatic dimensions of Schizophrenia.

Introduction

Schizophrenia is a heterogeneous disorder with diverse history, symptoms, and subtypes. These subtypes may be distinguishable from each other with respect to prognosis, course, or response to treatment. Their identification is of utmost importance from a clinical perspective. Earliest diagnostic refinements involved the subdivision of schizophrenia into positive and negative syndromes. [sup][1],[2] Delusions, hallucinations, and bizarre behavior were part of positive schizophrenia, while blunted affect, avolition, and attentional problems were salient features of negative schizophrenia. To investigate the positive-negative dichotomy empirically, measurement instruments such as the Scale for the Assessment of Negative Symptoms (SANS) and the Scale for the Assessment of Positive Symptoms (SAPS) were designed. [sup][3].[4] However, empirical analyses of these scales showed that positive symptoms can be further subdivided into psychotic and disorganized symptoms, [sup][5] suggesting that the positive-negative distinction does not fully explain the complex structure of schizophrenic symptoms.

The SANS and SAPS were developed to measure positive and negative syndromes. Because of a hypothesized selection of symptoms, these instruments may be limited in their potential to identify schizophrenia subtypes. To allow a more extensive assessment of schizophrenia symptoms, Kay et al . [sup][6] used the Brief Psychiatric Rating Scale developed by Overall and Gorham [sup][7] and the Psychopathology Rating Schedule developed by Singh and Kay [sup][8] to create more comprehensive Positive and Negative Syndrome Scale (PANSS). [sup][6] Many of the 30 items of the PANSS are not directly related to the positive and negative syndromes. To unravel the structure of the PANSS items, a considerable number of factor analyses have been performed. In these studies, the number of underlying factors derived varied, as were the PANSS items included in scales presumably measuring the same subtype.

In an endeavor to reconcile different research findings, White and colleagues [sup][9] fitted 20 previously proposed models to data from a sample of 1233 schizophrenics. They concluded that none of these models fitted the data adequately. The authors then derived a new model by performing exploratory factor analysis (EFA) in one-half of the data and cross-validating the derived model in the other half of the data. The five factors from this pentagonal model were labeled: positive, negative, dysphoric mood, activation, and autistic preoccupation. It is this five-factor model that is presently proposed in the manual for the PANSS. [sup][10] However, controversy surrounding the factor structure of the PANSS did not end with the study of White and colleagues. [sup][11],[12],[13] Critics argued that five factors may not be good enough to capture the structure of the PANSS items, [sup][11] and the proposed pentagonal model gives an inadequate goodness of fit in other sample. [sup][14]

Major work in the field of factor subtyping of schizophrenia in India has been done by Kulhara et al . …

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