1. Reliability and Validity
Of Diagnosis and Classification of Schizophrenia

2. • Classification of schizophrenia
• Classification of schizophrenia. Positive symptoms of schizophrenia, including hallucinations and delusions. Negative symptoms of schizophrenia, including speech poverty and avolition. Reliability and validity in diagnosis and classification of schizophrenia, including reference to co-morbidity, culture and gender bias and symptom overlap
• Biological explanations for schizophrenia: genetics, the dopamine hypothesis and neural correlates.
• Psychological explanations for schizophrenia: family dysfunction and cognitive explanations, including dysfunctional thought processing.
• Drug therapy: typical and atypical antipsychotics.
• Cognitive behaviour therapy and family therapy as used in the treatment of schizophrenia. Token economies as used in the management of schizophrenia
.. • The importance of an interactionist approach in explaining and treating schizophrenia; the diathesis stress model.

3. Starter
Complete the matching activity

4. Key Terminology Validity Reliability Co-morbidity Culture Gender bias
Symptom overlap

5. Diagnosis and classification
What do you think are the problems with trying to diagnose someone with schizophrenia? Mind-map your ideas

6. Reliability and Validity in Diagnosis
Is their reliability between different classification systems.
Is there reliability between clinicians.
Is there reliability over time.
Does diagnosis have clear predictive validity
Do people with schizophrenia get a diagnosis of schizophrenia

7. Reliability
Means consistency, so we are looking to ensure that a set of measures (or in the case of schizophrenia, observations / symptom measurement) are consistent.
If this is the case, then we can say that the same information, or observations / symptom measurement produce the same diagnosis.
Methods for this include:
Test-retest reliability: A practitioner makes the same consistent diagnosis on separate occasions from the same information.
Inter-rater reliability: Several practitioners make identical, independent diagnoses of the same patient. It should also be that two different classification systems will produce the same diagnosis.

8. Validity
Reliability does not necessarily guarantee validity, that the ‘test tests what it’s supposed to test’.
In relation to schizophrenia validity refers to the extent to which the classification systems are accurately diagnosing schizophrenia.
Reliability – a valid diagnosis has to first be reliable, though this is no guarantee of validity.
Predictive Validity – if diagnosis leads to effective treatment, the diagnosis can be seen as valid.
Descriptive Validity – to be valid, patients diagnosed with different disorders should differ from each other. (e.g. The description of schizophrenia should match the symptoms shown in individuals).
Aetiological Validity – to be valid, all patients with the same disorder should have the same cause.

9. Comorbidity
This is the phenomenon when 2 or more conditions occur together.
If conditions occur together this calls into question the validity of their diagnosis and classification because they might actually be a single condition
Sz is commonly diagnosed with other conditions
Depression (50%)
Substance abuse (47%)
PTSD (29%)
OCD (23%)
This raisesissues of descriptive validity
Schizophrenia might not be a separate order?

10. Symptom Overlap…
There is considerable overlap between the symptoms of Sz & other conditions:
Both Sz & bipolar disorder involve positive symptoms such as delusions & negative symptoms like avolition.
This calls into question the validity of the C & D of Sz.
Under ICD a patient might be diagnosed as a Sz however many of the same patients may receive a diagnosis of bipolar according to DSM.

11. Gender Bias
The tendency for diagnostic criteria to be applied differently to male and females and for there to be differences in the classification of the disorder. There is some disagreement between psychologists over the gender prevalence rate of schizophrenia. Cotton 2009 suggests this bias may lead practitioners to under-diagnose Sz either because symptoms are masked by good interpersonal functioning or because quality of interpersonal functioning makes the case seem too mild.

12. Cultural bias in diagnosis
African Americans and English people of Afro-Caribbean origin are several times more likely than white people to be diagnosed with Sz However rates in Africa are not high – thus not a genetic vulnerability One issue is that + symptoms may be more acceptable in African cultures because of cultural beliefs in communication in ancestors, thus people are more ready to acknowledge such experiences When these experiences are reported to a psychiatrist from a different culture, they are likely to be seen as bizarre and irrational

14. Activity
Task – Use the handout to explore this area and provide research evidence to back up issues with reliability and validity by answering the questions.
Challenge
What alternatives are there to using classification systems?
How do the classification systems aim to improve reliability and validity?
Go back to the key terminology – define all the points and then find evidence for co-morbidity, culture bias, gender bias and symptom overlap.

15. Does schizophrenia look the same in different people?
Plenary
Does schizophrenia look the same in different people?
Is the outcome of schizophrenia always the same?
Do we know exactly how to treat the condition. For example, do people always respond to antipsychotics?
Why does symptom overlap complicate the diagnosis of schizophrenia?
Why is co-morbidity a problem for diagnosis?

16. Discuss reliability and/or validity in relation to the diagnosis and classification of schizophrenia. (Total 8 marks)

17. Discuss reliability and/or validity in relation to the diagnosis and classification of schizophrenia. (Total 8 marks)
Possible Content:
Definitions of reliability in relation to diagnosis and classification – level of agreement on the diagnosis by different psychiatrists across time and cultures; stability of diagnosis over time given no change in symptoms
Definitions of validity – the extent to which schizophrenia is a unique syndrome with characteristics, signs and symptoms
Identification of issues such as range of symptoms across individuals, comorbidity and symptom overlap
Possible discussion points:
Use of evidence on the reliability of major classification systems (ICD IV, DSM IV or V)
Use of evidence on reliability of diagnosis between different clinicians and across different cultures
Range of different symptoms in different patients – positive and negative symptoms
Evidence on comorbidity with eg depression, mixed syndromes eg schizo-affective disorder, symptom overlap eg bipolar disorder
Factors affecting reliability and validity of diagnosis
Wider implications of reliability and validity of diagnosis eg labelling, cultural bias.
Material must be explicitly linked to reliability and/or validity to earn credit.

18. Task Individually, plan an answer to the below question
Discuss issues associated with the classification and / or diagnosis of schizophrenia.
(Total 16 marks)

19. AO1 There are many issues surrounding the classification and diagnosis of mental disorders in general, most of which are related in some way to the idea of reliability and validity. It is acceptable to describe overarching issues as long as they have relevance to schizophrenia. However, there are some issues which are particularly relevant to schizophrenia eg the range of sub-types of schizophrenia and the difficulty of distinguishing between them. Issues include: • The reliability of the major classification systems ICD and DSM. • The availability of other diagnostic criteria for schizophrenia. • The lack of homogeneity in schizophrenic symptoms. • The problems of labelling. • The problem of co-morbidity. • The problem of distinguishing schizophrenia from, for example, mood or personality disorders. • The lack of objective tests for schizophrenia. • The difficulty of being able to predict outcome or response to treatment. • Cultural differences in symptom presentation. • The question of whether schizophrenia is a mental disorder at all. AO3 Candidates should evaluate and offer commentary on the issues they have identified for example considering the consequences arising from the issue. They could discuss the advantages and disadvantages of using classification systems to diagnose schizophrenia. For example, diagnosis might lead to labelling which causes long-term problems for the person with schizophrenia in terms of getting / keeping employment or establishing relationships. On the other hand, careful diagnosis can lead to effective treatment programmes which would, otherwise, not be offered.