Positive & Negative Symptoms: a Helpful Concept?
One of the puzzling things about medicine is the language used and I don't just mean the technical stuff. For example, a positive result in medicine often means that there is something wrong whereas a negative result means you're o.k. - or does it?
When it comes to considering positive and negative symptoms in schizophrenia, the meanings do change somewhat. In this context, 'positive' actually refers to symptoms in addition to what might be considered standard behavior. Delusions and hallucinations would be considered examples of positive symptoms. By contrast, 'negative' symptoms refer to components that are reduced or missing from the normal repertoire. Social withdrawal and poverty of speech would be two such examples.
But why discriminate between positive and negative in schizophrenia at all? Well, the roots to this are embedded in the debate as to whether schizophrenia should be considered a single entity or not. As a result a number of researchers have undertaken some fairly complex statistical tests in order to identify whether naturally occurring symptoms can be distinguished.
In 1959 Kurt Schneider identified a set of symptoms that he considered primary in the sense that they did not appear to occur as a result of other symptoms. Schneider termed these symptoms first-rank and stated that in the absence of any organic disease or the effects of drug misuse any one of these was sufficient for a diagnosis of schizophrenia, e.g.
Auditory hallucinations (running commentaries on the person's actions or thoughts, or arguments about the person).
Thought echo or thoughts spoken out loud.
Thought insertions or thought broadcasting
Today, first-rank symptoms are still referred to, but a number of refinements have been added as illustrated in the following statement from the ICD-10 guidelines:
"A minimum requirement is one of the following symptoms: thought echo, insertion, withdrawal, broadcasting, passivity phenomena, delusional perception, third person hallucinations, and persistent delusions - all in clear consciousness. Other symptoms used to make the diagnosis (2 must be present) include persistent hallucinations in any modality, thought blocking, thought disorder, catatonic behaviour, negative symptoms, loss of social function." ICD-10.
Negative symptoms are really about losses or reductions in emotions, motivation and pleasures. These symptoms are often associated with social withdrawal, lack of conversation, indifference to appearance and sometimes indifference to personal safety. The behaviors associated with negative symptoms include an inability to change facial expression or body language according to mood, monotone voice and a sense of preoccupation or disinterest with surroundings. Caregivers will often state that it is the negative symptoms associated with schizophrenia that are the most difficult things to deal with. It is generally agreed that persistent negative symptoms result in long-term disability.
And Yet More?
Distinguishing between positive and negative symptoms seems to have had some benefits for diagnostic clinicians. However, some argue that it remains an over-simplistic concept and that there is ample evidence to contest these ideas. One such example originates in research by Liddle (1987) which has been replicated in a number of subsequent studies. Liddle argues for a three factor approach and distinguishes between:
Psychomotor poverty: flat emotions, lack of spontaneous movement.
Disorganisation: of thought, inappropriate emotional reponses.
Reality Disorientation: delusions and hallucinations.
But these aren't the only arguments. We musn't forget that still others argue that the flaws are even more fundamental because schizophrenia remains a convention rather than a fact.