classification + diagnosis of schizophrenia
classification of mental disorder
process of organising symtons into catergories based on which symtons frequently cluster together
ICD vs DSM
• manuals psychiatrists use to diagnose mental disorders
• slightly differ in classification of schizophrenia
• Eg: in DSM-5 one of positive symtons must be present for diagnosis whereas two or more negative symtons are sufficient under ICD
• diagnosis made possible by identifying symtons
positive symtons
• atypical symtoms experienced in addition to normal experiences
• include hallucinations + delusions
hallucinations
• positive symtoms of schizophrenia
• sensory experiences that have either no basis in reality or are disorted perceptions of things that are there
• Eg: hearing voices
delusions
• positive symtons of schizophrenia
• involve beliefs that have no basis in reality
• Eg: person believes that they are someone else or that they are a victim of a conspiracy
negative symptons
•aytpical experiences that represent loss of a usual experience such as loss of clear thinking or loss of motivation
speech poverty
• negative sympton of schizophrenia
• involves reduced frequency + quality of speech
avolition
• negative sympton
• involved loss of motivation to carry out tasks + results in lowered activity levels
• Andreason identified 3 signs of avolition: poor hygiene + grooming, lack of persistance in work or education, lack of energy
Rosenhan
• 8 confederates acted as psuedopatients + went into 12 different hospitals
• complained of hearing voices saying 'empty', 'hollow' + 'thud'
• once on ward psuedopatients behaved normally
• staff diagnosed 11 psuedopatients with schizophrenia + 1 with manic depression
• staff never detected sanity (35 real patients detected sanity saying 'you're not crazy')
• shows diagnosis flawed
co-morbidity
• occurence of two disorders or conditions together in the same individual at the same time
• where two conditions frequently diagnosed together it calls into question the validity of classifying the two conditions seperately
one strength of the diagnosis of schizophrenia is its reliability...
• psychiatric diagnosis said to be reliable when different diagnosing clinicans reach same diagnosis for same individual (inter-rater reliability) + when same clincian reaches same diagnosis for same individual on two occasions (test-retest reliability)
• prior to DSM-5, reliability for schizophrenia diagnosis was low but this has now improved
• Osório et al report excellent reliability for diagnosis of schizophrenia in 180 individuals using DSM-5
• pairs of interviewers achieved inter-rater reliability of +9.7 and test-retest reliability of +9.2
• means we can be reasonably sure that diagnosis of schizophrenia is consistently applied
a limitation of schizophrenia is its co-morbidity with other conditions...
• if conditions occur together a lot of time then this calls into question the validity of their diagnosis + classification because they might just be a single condition
• schizophrenia commonly diagnosed with other conditions
• according to Buckley et al, 50% of individuals with diagnosis of schizophrenia also have depression, 47% also have substance abuse, 23% also have OCD
• this is a problem for classification because it means schizophrenia may not exist as a distinct condition + and its a problem for diagnosis as at least some people diagnosed with schizophrenia may have unusual cases of conditions like depression
a further limitation of schizophrenia diagnosis is the issue of culture bias...
• some symptons of schizophrenia (particularly hearing voices) have different meanings in different cultures
• Eg: in Haitii some people believe that voices actually are communications from ancestors
• in addition to this, british people of afro-carribean origin are up to nine times more likely to recieve diagnosis as white british people (Pinto + Jones)
• most likely explanation of this is culture bias in diagnosis of clients by psychologists from different cultural backgrounds
• this appears to lead to overinterpretation of symptons in black british people (Escobar)
• means that british afro-carribean people may be discriminated against by a culturally biased diagnostic system