BIOL PSYCHIATRY 1992;31:431-434

431

EDITORIAL

Positive and Negative Symptoms in Schizophrenia: Where Are the Data?

Within the past year, Biological Psychiatry has published two editorials leviewing and criticizing the concept of negative symptoms. We propose a more radical critique. We believe that the distinction of positive and negative symptoms is basea on very little data, and propose that a valid classification of schizophrenic symptoms should use a multisyndromal model (with at least three syndromes). It is difficult to critically and briefly review the different models of positive and negative symptoms, as each researcher uses different definitions, and these are not interchangeable For example, there is only one negative symptom common to all negative symptom scales, that is, flat affect. The number of positive symptoms also varies widely among different scales. At the risk of being unfair, we will limit our review to the models proposed by Crow, Andreasen, Kay and Carpenter. Crow's model is based on two concepts: the existence of 1) positive and negative symptoms; and 2) two types of schizophrenia, I and II. 1) Crow used a modification of the Manchester scale to assess symptoms, and classified two as negative (flattened affect and poverty of speech) and four as positive (incongruous affect, delusions, hallucinations and incoherence). Very little information is available regarding the use of the Manchester scale in this regard. Crow and coworkers have never described the internal consistency of the positive and negative symptom subscale, nor have they carried out a factor analysis to determine whether this hypothetical classification is confirmed. The factor analyses of the Manchester scale, as far as we are aware, do not fit into Crow's classification of symptoms, and show that incoherence and hallucination-delusion do not load in the same factor (Perez Fuster et al 1989; Jackson et al 1990). 2) The distinction in types has never been operationalized. In the beginning, type II schizophrenia, characterized by negative symptoms, was considered to be a later stage of type I, characterized by positive symptoms. In a later model, Crow conceptualized type I and II as relatively independent processes, which may coexist .in the same patient and be different manifestations of the same pathogen. Type I is also characterized by absence of intellectual impairment and abnormal movements, by normal brain structure, and by good response to neuroleptics. Type II is characterized by anatomical abnormalities, poor response to neuroleptics and, at times, intellectual deterioration and abnormal movements. The proposed responsiveness and nonresponsiveness of the positive and negative symptoms to neuroleptic medication is inaccurate. Even Crow's coworkers' data show that 50% of chronic patients with negative symptoms did recover after 4 years. Since the introduction of neuroleptics, it appears that the deficit symptoms do not respond as well as positive symptoms, but this does mean that negative symptoms do not respond to neuroleptics, and ignores the fact that positive symptoms may also be resistant to neuroleptics. Studies using the Brief Psychiatric Rating Scale (BPRS) and those published by Kay show that negative symptoms may respond to neuroleptics. It is impossible though, © 1992 Society of Biological Psychiatry

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BIOL PSYCHIATRY 1992;3 ! :431-434

Editorial

to assess the effects of secondary negative symptoms and of spontaneous changes in the illness. It appears that Crow's model has served a most useful purpose but should be abandoned. Andreasen's model is based on two concepts: 1) the existence of three types of schizophrenia and 2) the classification of schizophrenic symptoms as positive and negative, l) Andreasen originally classified schizophrenia as positive, negative, or mixed, and tried to externally validate the distinction between positive and negative types of anatomical abnormalities and cognitive deficits. The mixed type has remained a grey area. Mixed schizophrenia is clearly the most frequent type in large samples (Pera!ta et al 1992), and its relative frequency appears to increase with the course of the illness. This has recently led Andreasen and coworkers (1990) to change the criteria used to classify mixed and negative syndromes. However, even with modification, the original results used to externally validate the types have not been replicated. 2) Andreasen proposed the Scale of Assessment of Negative Symptoms (SANS), which includes 20 symptoms grouped into five subscales for assessing negative symptoms, and the Scale for Assessment of Positive and Negative Symptoms (SAPS), which includes 30 symptoms grouped into four subscales, to measure positive symptoms. Bilder and coworkors (1985) and Liddle (1987), in two rather neglected studies using the SANS, point out that the classification of positive and negative symptoms does not appear valid. They used factor analysis to explore the classification of the symptoms Independently, they determined that the symptoms should be classified into three syndromes: a delusional-hallucination syndrome, a disorganization syndrome (formal thought disturbances and, depending on the study, attention, inappropriate affect, and bizarre behavior) and a negative symptoms syndrome. Their studies are ham~red by small samples (

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

BIOL PSYCHIATRY 1992;31:431-434 431 EDITORIAL Positive and Negative Symptoms in Schizophrenia: Where Are the Data? Within the past year, Biologica...
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