One distinct sign of schizophrenia is the course the illness can take. For example, the acute phase is characterised by psychotic or positive symptoms. Subsequently, deficit or negative symptoms depict moving into the lasting phase (Bhanji & Tempier, 2002). An accepted progression may create a problem for diagnoses if trying to categorise a person when the symptoms blend. In this instance, the distinction between positive and negative symptoms is not useful. Robert Carson (1996) argues, a ‘categorical system’ (such as DSM) for schizophrenia will never yield to such a system because of its ‘seamless’ characteristics. Carson believes a discourse for causes of schizophrenia are a result of its current "taxonomic conundrum" (Carson, 1996, p. 1137). The DSM seems to recognise this by not using the phrase ‘positive symptoms’ in the characteristic symptoms, instead using ‘hallucinations’ and ‘delusions’ (APA, 2000).

The above two investigations justify usefulness in grouping symptoms, but the criteria have changed. For instance, behavioural aspects of schizophrenia observed by Schneider were reorganised by a research team headed by Andreasen. She used differential statistics to group the symptoms that loaded with each other, in terms of treatment and research responses. Clearly, empirically validated conclusions about the disorder should be incorporated into diagnostic criteria. Especially in forming a solid foundation for future research which could be hampered if different interpretations are used. Such research has influenced changes in criteria as seen in the DSM since its first publication in 1952 (Davidson, Neale & Kring, 2004).

Clearly one mistake would be to generalise a persons symptoms as positive and negative. For example, two patients can have a firm diagnosis of schizophrenia and display completely different symptoms from both clusters. One patient could suffer from delusions on the one side and avolition on the other. Another patient could suffer from acute hallucinations yet both people could be schizophrenic. Andreasen, Arndt, Alliger, et al. (1995) address this issue explaining the use of terminology which should be used to refer to exaggerations of normal functions versus loss of normal functions. For instance, "positive symptoms are understood as those that are more florid and that tend to be more associated with exacerbations of the illness, while negative symptoms tend to have a basic underlying persistence" (Andreasen, Arndt, Alliger, et al, 1995, p. 347).

Kraepelin grouped mental diseases that were previously considered unrelated under the term dementia praecox. The distinction between ‘fundamental’ and ‘accessory’ symptoms were subsequently recognised (Phillips & Ketelsen, 2003). However, a Swiss psychiatrist Eugen Bleuler adjusted Kraepelin's theory. For instance Bleuler in 1908 claimed the disease was an organic brain deterioration and thus incurable and introduced the term schizophrenia to replace dementia praecox (Phillips & Ketelsen, 2003). Dementia praecox, according to Kraepelin, was "the young becoming old before their time" (Phillips & Ketelsen, p. 25, 2003).

The issue of referring to symptoms as positive and negative is becoming a topic of interest as the scope and causes of schizophrenia become more understood. Causes of schizophrenia can originate biologically. The use of positive and negative symptomatology is helps to understand the causes of schizophrenia. For instance, research of neurocognitive correlates of positive and negative symptoms of schizophrenia found negative symptoms in particular were associated with information processing tasks (Voruganti, Heslegrave and Awad, 1997). Also, the negative symptoms of schizophrenia, in contrast to the positive symptoms, are less likely to respond to medical treatment (Moranville, 1995). Further, research into brain studies show the volume of white matter in the frontal lobe area to be in a state of gradual lesse

Some topics in this essay:
Harris Macdonald, Arndt Alliger, Andreasen Nopoulos, Neale Kring, Heslegrave Awad, Robert Carson, Nancy Andreasen, Phillips Ketelsen, Stone Faraone, Eugen Bleuler, negative symptoms, positive negative, positive negative symptoms, positive symptoms, et al, symptoms schizophrenia, drug therapy, causes schizophrenia, phillips ketelsen, characteristic symptoms, negative symptoms schizophrenia, phillips ketelsen 2003, hallucinations delusions, arndt alliger et, et al 1995,