The positive:negative dichotomy in schizophrenia

Article Abstract:

Since the earliest days of classifying schizophrenia, attempts have been made to assign symptoms to one of two broad classes, generally known as positive and negative. Positive symptoms are those that are characterized by the presence of abnormal behavioral phenomena, such as delusions or hallucinations. Negative symptoms, on the other hand, are deficits or diminutions in normal function, such as loss of emotional affect, will, or speech. In recent years, this classification scheme has been called into question, with some claiming that the two symptom sets are not independent, and others suggesting yet a third category of symptoms known as 'disorganization.' Two studies are described which were intended first, to examine the independence of positive and negative symptoms, and second, to determine the status of the symptoms of thought disorder, catatonia, and cognitive impairment within the context of the positive:negative scheme. In the first study, 62 schizophrenics were evaluated using two scales, the High Royds Evaluation of Negativity (HEN) and the Schedule for Assessment of Negative Symptoms (SANS), to measure negative symptoms. A third scale was used to measure all psychiatric symptoms, and correlations between various scores were calculated. Similarly, the second study, involving 80 schizophrenic patients, measured negative symptoms as well as cognitive function and motor disorders. The presence of negative symptoms could not be correlated with positive symptoms, confirming the validity of a positive:negative dichotomy. Based upon the results of the first study, it is supposed that negative symptoms are more fundamental in schizophrenia, as they correlate most consistently with the diagnosis. The results of the second study reveal that formal thought disorder appears to be a positive symptom, as does poverty of content of speech, even though it appears to be a deficit. It is also concluded that catatonia can be divided into both positive and negative symptomatology. Cognitive impairment seems to be an ill-defined set of conditions that are affiliated with various schizophrenic symptoms. (Consumer Summary produced by Reliance Medical Information, Inc.)

Methods, Diagnosis, Cognition disorders, Cognitive disorders, Symptomatology, Signs and symptoms

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Correlates of positive and negative schizophrenic syndromes in Nigerian patients

Article Abstract:

In 1980, T.J. Crow defined two schizophrenic syndromes; type I includes positive or florid symptoms such as delusions, hallucinations, and thought disorder, while type II is marked by negative or deficit symptoms, including mood flattening, poverty of speech, and muteness. There has been some empirical support for the idea that type I is caused by excess activity of dopamine (a substance involved in the transmission of nerve signals) and that type II is related to neurologic alterations. For example, the negative syndrome is usually less responsive than the positive syndrome to neuroleptic (antipsychotic) medication, which blocks dopamine activity. Most studies of types I and II have been carried out in Western, industrialized countries. To assess the universality of Crow's theory, a study of 147 Nigerian psychiatric in-patients was carried out. The patients were administered a battery of tests to assess mental state, positive and negative symptoms, cognitive functioning, motor and sensory variables, eye dominance and handedness. Ward nurses rated each patient's behavior. Data analysis revealed that males had a longer duration of current in-hospital stay and received lower doses of neuroleptics than females. The negative syndrome was found to be significantly related to longer length of current hospital stay, lower level of education, poor cognitive test performance, left eye dominance and deterioration. None of the variables tested were found to be significantly related to the positive syndrome. The relationship found between type II syndrome and left eye dominance seems to support Crow's view that the type II syndrome is related to neurological factors. Results also suggest that variables associated with deficit states in industrialized countries are also significant for patients from third world countries. (Consumer Summary produced by Reliance Medical Information, Inc.)

Influence, Nigeria, Psychiatry, Transcultural, Transcultural psychiatry, Crow, T.J.

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Aetiological heterogeneity of schizophrenia: the problem and the evidence

Article Abstract:

When the mental illness now known as schizophrenia was first categorized by Kraepelin about a century ago, it was considered to have a single cause, as many of Kraepelin's patients, though falling into different diagnostic categories, tended to end up in a similar demented state. Later, in 1911, Eugen Bleuler, who coined the term ''schizophrenia,'' referred to ''schizophrenias'' in the title of an article. Thus the debate over whether schizophrenia is a single disease with a single cause, or a class of diseases with different causes, has a long history. In current literature on the disorder, the assumptions regarding its nature and cause tend to be inconsistent and based on convenience. The authors discuss the logical reasons for abandoning the concept of schizophrenia as having a single cause, in light of a review of a number of studies, which suggest different causes of the disorder on the basis of evidence ranging from brain damage to season of birth. Noting that the only proof necessary to refute such a statement as ''All swans are white'' is a black swan, the authors conclude that the preponderance of findings of different causes of schizophrenia means that it is time to abandon the single-etiology theory of schizophrenic disorders. (Consumer Summary produced by Reliance Medical Information, Inc.)

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