Mental illness is as old as humankind. Schizophrenia is a mental illness and one that impacts how people think, feel and act (Phillips & Ketelsen, 2003). The exact causes of schizophrenia are not yet known (Tsuang, Stone, and Faraone, 2000) so consequently, careful attention in the following areas of aetiology, diagnostic criteria, treatment and research are critical. This essay explores the distinctiveness of positive and negative symptoms of schizophrenia in the four areas just mentioned. Andreasen (1987) and Kay, Fiszbein and Opler (1987), have defined positive symptoms as hallucinations, delusions and disorganised thinking and negative symptoms are characterised by deficits in cognitive, affective, and social functions, including blunting of affect and passive withdrawal. It is hypothesised that it is beneficial to generalise the array of symptoms into discrete categories such as positive or negative, but only under certain circumstances. This is especially the case when communicating between the four areas mentioned above. Nancy Andreasen (1999) claims that understanding of the signs and symptoms of schizophrenia is diverse and its causes have multiple factors. Generalising signs and symptoms when talking about schizophrenia is therefore useful.
One hundred years ago Emil Kraepelin (1856-1926) and Eugen Bleuler (1857-1939) characterised diagnostic criteria and their ideas continue to inspire others today. For example, the term schizophrenia and its criteria such as the four A's: disturbance of affect, autism, ambivalence and disturbance of associations (Tsuang, Stone and Faraone, 2000); are still used today. .
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.