Validity Issues Reliability Issues Classification of Schizophrenia Diagnosis

Validity Issues Reliability Issues Classification of Schizophrenia Diagnosis of Schizophrenia

Classification and Diagnosis L. O. Evaluate the reliability and validity of SZ Classification and Diagnosis • “Issues surrounding the classification and diagnosis of their chosen disorder, including reliability and validity”

Diagnostic Ideals An ideal diagnostic system has certain characteristics: • The categories are mutually exclusive – they do not overlap • The categories are exhaustive – they cover the whole range of possible categories • Features of a disorder must be either present or absent – we can make yes/ no decisions based on the description • The system should be valid and reliable

To get us going. . . • How is Classification different from Diagnosis? • How do we apply the concept of Validity and Reliability to the classification and diagnosis of Schizophrenia? Classification Reliability Validity Diagnosis

Classification and Diagnosis 2 separate but related issues: • Classification = defining what Sz is. • Diagnosis = Whether a particular case / person meets the classification

Reliability and Validity • Reliability = consistency of classification system and/or case diagnosis – i. e. is it classifying / diagnosing the same thing over time? • Validity = objectivity of classification system and/or case diagnosis – i. e. classifying / diagnosing what it THINKS it is classifying / diagnosing?

Sz – Reliability Issues Surrounding Classification & Diagnosis • Extent to which psychologists agree on: – Definition of Sz (classification) – Diagnosis of individual cases (diagnosis) • Ongoing development of classification systems • Issues with cultural bias (DSM and ICD) Whaley (2001) inter-rater reliability = 0. 11 • Positive symptoms more useful for diagnosis

Sz – Validity Issues Surrounding Classification & Diagnosis • Extent to which psychologist’s opinion reflects objective reality on: – What this Sz ‘thing’ IS – If individual cases have that ‘thing’ (Sz) • As classification systems are not same / consistent then at least SOME were/are ‘wrong’ • Difficult to define the SZ disorder from others • Validity of subtypes are questioned as some overlap • If inter-rater reliabilty is low, then some must be wrong in their diagnosis, but who?

Classification Reliability Validity Diagnosis Is there consistency in describing what Sz is over time between classification systems? Do different psychiatrist agree on the diagnosis of individual cases (i. e. inter-rater reliability)? How accurately do the classification systems actually describe an objective reality (i. e. does Sz exist as it is described? !) Are the diagnoses made accurate in identifying which cases HAVE Sz and which do not? [remember drapetomania? ]

Soooooo • To classify or not to classify; that is the. . . *wotsit. . thing we have to consider, starts with a Q. . . )* • Does all this mean ‘classification’ is worthless? • Are there any wider social issues that need considering when it comes to classification? • Is there any benefit to having a classification system for Sz?

Social Labelling • Scheff (1999) promoted the labelling theory of schizophrenia. • Theory states social groups create the concept of psychiatric deviance by constructing rules for group members to follow. • Thus symptoms of schizophrenia seen as deviating from the rules that we attribute to ‘normal’ experience or behaviour. • Those who display unusual behaviour are considered deviant & the label Sz may be applied, becoming a self fulfilling prophecy promoting the development of other symptoms of schizophrenia

But, in DEFENCE of classification • Blaney (1975) argued that the tendency to think of abnormal behaviour, as an illness is more humane. “Ill” sounds better than “mad”. Gross(1992): Outlined the goals of classification, which were: • To provide a common language with agreed on meanings. • The understanding of the origins of disorders. • treatment plans

“Outline clinical characteristics of Schizophrenia” (5 marks) • Schizophrenia is a disorder characterised by distorted thinking, hallucinations, impaired emotional response and distortion of reality. (1 mark) Characteristics of schizophrenia are found in the DSM-IV. Characteristics must be present for at least six months although the ICD states the most important symptoms be present for only 1 month (2 marks ). Characteristics include positive symptoms such as, withdrawal, persistent delusions, thought echo, incoherent or rambling speech and cationic behaviours. (3 marks)Negative symptoms are those such as, blunting or lack of emotional response. (4 marks)There are sub-types of Schizophrenia such as Catonic which is characterised by unusual motor activity, extreme negativity and peculiar posturing (5 marks).