Schizophrenia - Diagnosis and Classification

Positive Symptoms

Positive Symptoms are in addition to normal functioning

  • Hallucinations Experiencing things which aren't there. Auditory hallucinations are the most common.
  • DelusionsErroneous beliefs which involve misinterpretation of perception. Persecutory, Referential and Grandiosity are three types of delusion.
  • Disorganised ThinkingThe feeling that thoughts have been inserted or withdrawn from the mind. Someone may believe their thoughts are being broadcast. It cannot be directly observed but presents itself through disorganised speech. For example derailment, word salad and clang.
  • Disorganised BehaviourThis could be child like behaviour, unprovoked agitation, dressing in an unusual mannor and a disruption in hygene and daily life.
  • Catatonic Motor BehaviourThere are different types of catatonic behaviour, catatonic negativism, catatonic posturihng and rigidity and finally catatonic excitement.
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Negative Symptoms

Negative Symptoms are a loss of normal functioning

  • Affective Flattening - The range of emotional responsiveness is diminished. There is reduced body language and poor eye contact
  • Alogia - The person appears to have a diminuation of thoughts which is shown in a decreased fluency and productivity of speech.
  • AvolitionAn inability to initiate and persist in goal directed behaviour. They may sit for long periods pf time and show little interest in participating in work or social activities. 
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  • The person must have been experiencing 2 symptoms for 1 month.
  • Some signs must continue for 6 months
  • Some symptoms are characteristics of the dissorder so you only need 1 such as bizarre delusions to be diagnosed with the dissorder. 
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Types of Schizophrenia

Paranoid Schizophrenia

  • Mostly positive Symptoms 
  • Delusions are typically persocutory and grandiose
  • Late onset

Hebephrenic Schizophrenia

  • When dissorganised speech and behaviour are the most prominant 
  • Dellusions and Hallucinations are not organised into a coherent theme
  • Early onset

Catatonic Schizophrenia

  • Mainly Negative Symptoms
  • Catatonic motor behaviour is prominant
  • Echolalia - constant repetition of words spoken by another
  • Echopraxia - repetition of another's movement 
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DSM and ICD summary

The Diagnostic & Statistical Manual - Latest version published in 2000

The International Classification of Diseases - Latest version published 1992


  • DSM requires symptoms to be evident for 6 months while ICD requires 1 month.
  • ICD places more empthasis on first rank symptoms while DSM emphasises the course of the dissorder and functional impairment.
  • Two classification systems differ in the way they catagorize schizophrenia. ICD lists 7 subtypes. DSM identifies 5 subtypes. 
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Issue 1 - The use of multiple diagnostic manuals

Different countries using different diagnostic tools creates the issue of reliability. Specifically Inter-Rater Reliability. Two different therapists may not agree on the diagnosis of one patient. If the clinicians agree then the inter-rater reliability is high.

Consequences - AO2

Motjabi & Nicholson found 50 senior psychiatrists had low inter-rater reliability when distingiushing between bizarre and nonb-bizarre delisions, despite delusions being a central feature in diagnosing schizophrenia.

Copeland found 194 British and 134 American psychiatrists when asked to provide a diagnosis based on a case description; 69% of Americans diagnosed the disorder while only 2% of the British did. 

Beck looked at classification of schizophrenia with the DSM. 4 psychiatrists discussed the DSM criteria to ensure they aggreed how it would be applied. They made a diagnosis for 153 patients. They only agreed in 54% of hte cases. This was even less when it came to the subcatagories. Even when using the same diagnostic tool there is still low inter-rater reliability.  

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Issue 2 - Construct Validity

The concept of schizophrenia has been criticised as some wonder if it is a genuine dissorder. Davidson et al staes the catagories we use to determine mental illness are constructs. This means the symptoms and catagories of schizophrenia are subjective and based on the opinions of clinicians.

This differes from diagnosis of illness such as diabetes. This is because we know the exact cause and there can be biological tests done. Therefore doesn't require a subjective opinion based on constructed sets of symptoms. Psychologists don't know the cause of schizophrenia. 

Consequences - AO2

Validity is concerned with accuracy. The main consequence of using socially constructed symptoms is concerned with misdiagnosis. The question is, is schizophrenia a real dissorder and do people with dissorder actually have it. 

Motjabi and Nicholson's study can be used.

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Issue 3 - There is no definitive cause

There is no cause to psychological dissorders. Knowing the cause of an illness is directly related to the ability of diagnosing it. Due to there being so many causes of schizophrenia this effects the accuracy of diagnosis. 

Aetiological Validity refers to whether or not schozophrenia has the same cause for everyone. All patients diagnosed should have the same cause for schizophrenia to be a valid catagory. For example genetics is thought to be a cause, so everyone which suffers from schizophrenia should have a family history of the dissorder. 

Consequences AO2

It is difficult to establish a common aetiology in people with schizophrenic symptoms. This is due to the range of factors. People with temporal lobe epilepsy show similar symptoms to those with schizophrenia. Prescribed drugs can cause psychosis and schizophrenia. Therefore it is important for the clinician to carry out a careful diagnosis.

Look at Types of Schizophrenia Card - Don't all share the same symptoms

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Issue 4 - Cultural Differences in Diagnosis

Harrison 1998 Schziophrenia efects 1% of the population world wide. USA and UK diagnose schizophrenia more frequently in African Caribbean populations. 

This could be due to misdiagnosis. Clinicians may misinterpret cultural differences in behaviour as schizophrenic symptoms. Bizarness of delusions are difficult to judge across cultures. There are cases of people seeing visions viewed positively in one culture but labelled schizophrenic in another. The classification system is Culturally Biased. Diagnosing behaviour from one cultures perspective affects the validity of diagnosis of schizophrenia when using them as they wouldn't be accurate. 


Lopez 1996  argues a consequence of cultural differences is to cause clinicians to over or underestimate psychological problems in members of other cultures. African-Caribbea people in the UK are more likely be diagnosed as schizophrenic and compulsorily committed to psychiatric hospitals. Fernando 1988 they are also more likely to recieve ECT.

Winter 1999 suggets ethnic minorities are less likely to be referred for psychotherapy than whites. Similar results are found between WC and MC and women and men. This is due to the majority of psychiatrists being white middle class males. 

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Issue 5 - Schizophrenia has too many Symptoms

Allerdyce 2006 suggest that symptoms used to catagorize schizophrenia do not define a specific syndrome but a number of different combinations. If patients present symptoms that don't fit one of the subtypes then a further set of disorders are offered such a schizoid personality disorder and schizoaffective disorder.

Consequences AO2 

Schizophrenic symptoms can overlap with other disorders such as depression and bipolar disorder. Ellason and Ross 1995 point out people with dissociative identity disorder have more schizophrenic symptoms than people diagnosed with schizophrenia. 

People who have been diagnosed with schizophrenia can present different problems. If there was a single underlying cause we would expect each person with schizophrenia to show the same characteristics. 

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Issue 6 - Unreliability of Symptoms due to Comorbi

Comorbidity is a patient which suffers from two of more mental disorders at the same time. People with schizophrenia show comorbidity as they often have bipolar disorder or an anxiety disorder. Some symptoms overlap each other. 

Major depressive disorder and schizophrenia inbolve very low levels of motivation. This creates issues of reliability as it is unclear what the low levels of motivation indicate. Therefore between psychiatrists it reflects reasons for low inter-rater reliability due to the cross over of symptoms.

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Social implications of misdiagnosis AO2 (Issue 6)

There is a stigma attatched to schizophrenia. The social stigma is considerable and can have a long-lasting impact on those diagnosed. This is why validity is important as the schizophrenic label is hard to get rid of. If there are issues with validity then it can have ethical implicaltions on the wwellbeing of those misdiagnosed. 

Kim Berrios 2001 researched Japan and the disease of the disorganised mind. Berrios found that this disorder is so stigmatised psychiatrists are reluctant to tell patients their condidtion. As a result only 20% of those with schizophrenia know they have it.

Marius Romm and Paul Hammersley proposed that diagnosis of schozphrenia is unscientific and damaging. Both are part of a new campain called campaign to abolish the schizophrenia label (CASL). It should be replaced with post-traumatic psychosis. This echos the view of Thomas Szasz who believed mental illness is a myth. 

If you are talking to God you are praying but it God talks to you, you are schizophrenic - Thomas Szasz, The Myth of Mental Illness 1961

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