Schizophrenia: topic 2 ‘reliability and validity in diagnosis’

Question 1

what are the two issues with the validity of the classification and diagnosis of SZ?

Answer 1

• gender bias: said to occur when the accuracy of diagnosis is dependant on the gender of the individual (eg some argue that the diagnostic criteria may be biased towards one gender rather than the other), clinicians may also base their judgements on stereotypical believes held about the gender
• symptom overlap: some symptoms of SZ are also found in other disorders such as depression and bipolar disorder (eg both SZ and bipolar involve positive symptoms such as delusions and negative symptoms such as avolition), makes it very difficult to accurately distinguish SZ from related disorders during diagnosis

Question 2

define comorbidity

Answer 2

• extent to which two or more conditions co-occur (eg many people diagnosed with SZ may also suffer from symptoms of depression, anxiety or substance abuse)
• this creates difficulty in separating these different conditions and also deciding what treatments to advise

Question 3

evaluation of gender bias in diagnosis of SZ

Answer 3

• evidence from Loring and Powell
• found that when a group of randomly selected male and female psychiatrists were given a case described as ‘male’, 56% of the psychiatrists gave a diagnosis of schizophrenia and when the case was described as ‘female’, only 20% were diagnosed as having schizophrenia
• Gender bias was not as evident among the female psychiatrist
• This suggests that diagnosis lacks validity as it is subjective based on gender stereotypes and not just facts of the case (eg symptoms)

Question 4

Evaluation of symptom overlap and diagnosis of SZ

Answer 4

• evidence from Ellason and Ross
• they pointed out that not only is there a great deal of overlap between SZ and bipolar disorder, but people with another disorder called dissociative identity disorder (DID) actually have more symptoms of schizophrenia than people diagnosed as being schizophrenic
• This is a problem as it brings into question whether SZ, bipolar disorder and DID a separate disorders at all or are part of the same spectrum

Question 5

evaluation of comorbidity

Answer 5

• evidence of comorbidity issues from Buckley
• found out comorbid depression occurs in 50% of patients and 47% have a diagnosis of comorbid substance abuse
• This suggests there is a significant overlap between disorders which makes the diagnosis of schizophrenia as a distinct disorder often very difficult

Question 6

what is the issue with reliability of the classification and diagnosis of SZ?

Answer 6

• culture bias: may lead to problems with both the reliability and validity of the diagnosis, culture bias is when psychiatrists are influenced by their own cultures values and expectations when diagnosing patients, if what is seen as bizarre in one culture is not viewed as bizarre in another, this could lead to inconsistent diagnosis

Question 7

evaluation of issues of reliability in classification and diagnosis of SZ (3)

Answer 7

• Evidence for interobserver reliability in diagnosis comes from Copeland who found that when British and American psychiatrist were given a description of a patient and asked for a diagnosis, 69% of the Americans diagnose schizophrenia but only 2% of the British did, this suggests diagnosis has very low interobserver reliability between cultures
• Furthermore, the fact that patient from certain cultural groups are more likely to be diagnosed with schizophrenia than others might suggest validity issues too, Harrison reported that afro Caribbean groups were eight times more likely to be diagnosed with schizophrenia than white groups in the UK, suggest psychiatrist may be misinterpreting cultural differences in behaviour as bizarre and therefore schizophrenic symptoms when they are simply just differences, ethnocentric bias would reduce the validity of diagnosis
• However it is also possible that there are genuine differences between cultural groups caused by genetic inheritance of schizophrenia, it could represent the effects of poor housing, higher rates of unemployment and social isolation that are more commonly experienced by minority groups such as Afro-Caribbean groups
• A major consequence of invalid or unreliable diagnosis of schizophrenia relates to the social stigma carried by being incorrectly labelled, such inaccurate diagnosis can have long lasting negative impact on the lives of those diagnosed, the classification systems do at least allow professionals to share a common language which helps in communicating ideas and also allows great opportunities for research which can lead to a better understanding of schizophrenia