Classification and Diagnosis of Schizophrenia

Discuss issues surrounding the classification and diagnosis of Sz- refer to reliability and validity in your answer (24 marks)

When classifying Schizophrenia (Sz) the symptoms are usually divided into two groups; positive (add something to sufferers lives) e.g. delusions, experiences of control, hallucinations and disordered thinking, and negative (take something away from sufferers lives) including; affective flattening- reduction in the range and intensity of emotional expression, alogia- poverty of speech, and avolition- the reduction of goal- directed behaviour.

However, in evaluation, these symptoms are unreliable as for a diagnosis only one of the characteristic symptoms are required ‘if delusions are bizarre’. This creates problems for diagnosis as when 50 senior psychiatrists in the US were asked to differentiate between ‘bizarre’ and ‘non-bizarre’ delusions, they produced inter-rater reliability correlations of only about +0.4. This consequently shows that even this central diagnostic requirement lacks sufficient reliability.

Furthermore, many of these symptoms are also found in other disorders, such as depression and bipolar disorder. People with Dissociative Identity Disorder actually have more Sz symptoms than people who are being diagnosed with Sz, and there is no universally agreed definition, therefore questioning the extent to which a diagnosis is valid and actually distinct from other disorders.

As well as the large range of symptoms, Schizophrenia can be categorised as either a Type 1 syndrome (an acute disorder characterised by positive symptoms) or a Type 2 syndrome (a chronic disorder characterised by negative symptoms). Furthermore, there are also 7 different subtypes of Sz, therefore, questioning the validity of classification as it may not be that all these different types of Sz actually exist, and a lot of the boundaries between categories are blurred making diagnosis’s subjective.

This subjectivity means that often diagnoses are based on a psychiatrics opinion, leaving it very open to abuse. For example, some diagnoses lack validity and instead have been made for political reasons e.g. in the Soviet Union psychiatrists colluded with the government to classify political opponents as mentally ill due to the negative stigmas attached.

Classification systems are what is used to diagnose mental disorders, however there are inter-rater reliability issues between the two main diagnostic systems. This is because the ICD lists 7 subtypes and emphasises first rank symptoms, whereas the DSM only lists 5 and emphasises the course of the disorder and the accompanying functional impairment. This can cause reliability issues as studies have found that Sz is more frequently diagnosed according to the ICD than the DSM.