reliability and validity in schizophrenia diagnosis

Question 1

what do doctors use to diagnose mental disorders?

Answer 1

a book called the DSM

Question 2

according to the dsm, a patient should be diagnosed with schizophrenia if they display what?

Answer 2

patient must present at least one positive symptom

Question 3

what does the ICD (international classification of disease) include?

Answer 3

all medical disorders

Question 4

according to the ICD, what does a patient need to display to be diagnosed with schizophrenia?

Answer 4

patient need only present 2 negative symptoms

Question 5

when is a diagnosis classed as reliable?

Answer 5

• when multiple doctors give the same diagnosis, the diagnosis is therefore consistent. so they are reliable
• for different patients with the same symptoms, one doctor giving all the patients the same diagnosis consistently would also be reliable.

Question 6

when is a diagnosis classed as valid?

Answer 6

• a diagnosis is valid when the criteria used to make the diagnosis allows us to correctly identify people who have a particular illness

Question 7

what is inter-rater reliability? and what do researchers use this to assess?

Answer 7

• when multiple people make the same measurement to see how similar their measurements are
• researchers use inter-rater reliability to assess the reliability of a diagnosis of schizophrenia

Question 8

when and what did aaron beck measure?

Answer 8

in 1962, a researcher called aaron beck measured the inter-rater reliability of schizophrenia diagnosis.

Question 9

what did aaron beck find?

Answer 9

he found that the diagnoses made by doctors were around 52% similar, meaning doctors were often disagreeing with each other and therefore the diagnoses lacked reliability.

Question 10

measures of inter-rater reliability made in 2005 found what?

Answer 10

found that diagnoses of schizophrenia were 87% similar.

Question 11

what does the 2005’s study and aaron beck’s study suggest about the inter-rater reliability of schizophrenia diagnosis?

Answer 11

these results suggests that the reliability of the diagnoses is getting better over time.

Question 12

when did rosenham conduct his study?

Answer 12

in 1973

Question 13

what happened in rosenham’s study?

Answer 13

rosenham got 8 volunteers to go to a mental health hospital.
the volunteers were all mentally healthy but were told to pretend they were hearing voices. in other words, they were told to pretend they were having hallucinations.
once the volunteers were admitted into hospital, rosenham instructed them to start behaving normally again.
rosenham waited to see how long it would take doctors to realise the volunteers weren’t schizophrenic and that they were actually mentally healthy
once the volunteers were in the hospital behaving normally, even there normal behaviours were interpreted as if they were abnormal. for instance, when the volunteers took notes in their diary, the doctors would report that they were displaying writing behaviour.

Question 14

what did rosenham find?

Answer 14

• the first volunteer was released after 7 days but the final volunteer was only released after 52 days in the hospital.
• rosenham found that doctors in the hospital made incorrect diagnoses of the volunteers. for many days, the doctors believed that the volunteers had schizophrenia and interpreted the volunteers behaviour as evidence of their schizophrenia even though they were actually healthy.
• so rosenham found that the doctors diagnosis lacked validity

Question 15

what are the 4 main issues that reduce validity and reliability of schizophrenia diagnosis?

Answer 15

• cultural bias
• gender bias
• co-morbidity
• overlap of symptoms

Question 16

what is cultural bias?

Answer 16

where researchers misrepresent the differences between cultures

Question 17

what is ethnocentric bias?

Answer 17

when someone assumes that other cultures behave the same as their own

Question 18

how does cultural bias reduce the reliability of a diagnosis?

Answer 18

cultural bias means that doctors may be more likely to diagnose someone from another culture with a mental disorder. this means that the same patient might get a different diagnosis depending on the cultural background of their doctor. this inconsistency therefore reduces the reliability of the diagnosis

Question 19

how does cultural bias reduce the validity of a diagnosis?

Answer 19

since using the DSM criteria, a doctor might incorrectly diagnose a patient with schizophrenia. this means the diagnosis might lack validity.

Question 20

where does evidence for cultural bias in schizophrenia diagnosis come from?

Answer 20

studies conducted by a medical organisation called cochrane

Question 21

when and what did cochrane investigate?

Answer 21

in 1977, cochrane investigated how commonly people were diagnosed with schizophrenia across britian and across the caribbean.

Question 22

overall, how many people are diagnosed with schizophrenia in britain and the caribbean?

Answer 22

overall, 1% of people were diagnosed with schizophrenia in britain. 1% of people were diagnosed with schizophrenia in the caribbean. so, the rate of schizophrenia diagnosis was similar in both places.

Question 23

what did cochrane find?

Answer 23

when cochrane looked at the rate of schizophrenia diagnosis within britain, they found that people of african-caribbean origin were 7x more likely to be diagnosed with schizophrenia compared to people of african-caribbean origin living in the caribbean.

Question 24

what did cochrane conclude?

Answer 24

cochrane concluded that african-caribbean people living in britain were being over diagnosed with schizophrenia due to cultural bias because doctors in britain were judging the patients using the social norms from their own culture

Question 25

what is gender bias?

Answer 25

when the differences between men and women are misrepresented.

Question 26

what are the 2 ways gender bias can occur?

Answer 26

1) doctors may display alpha bias and over-exaggerate differences in men and women’s behaviour
2) doctors can display beta bias and ignore real differences between men and women

Question 27

in both of these cases where gender bias can occur, what can it cause men or women to be? how can gender bias reduce the reliability of a diagnosis?

Answer 27

misdiagnosed.
so they are given an incorrect diagnosis of schizophrenia or their schizophrenia is ignored. this means that patients with the same symptoms might get different diagnoses depending on their gender reducing the reliability of the diagnosis.

Question 28

if the criteria used to diagnose schizophrenia over or under-exaggerates the differences between men and women, then what will happen?

Answer 28

then they wont correctly identify schizophrenia in all men and women. this reduces the validity of the diagnosis

Question 29

when and what did loring and powell investigate?

Answer 29

In 1988, loring and powell investigated whether the gender of a patient effects the diagnosis the patient receives.

Question 30

what happened in loring and powell’s investigation?

Answer 30

they gave a bunch of doctors descriptions of a patient. some doctors recieved a description that said the patient was male and some received a description that said the patient was female. but the patient always had the exact same symptoms.
the doctors were asked to diagnose the patient.

Question 31

what did loring and powell find?

Answer 31

when the patient was described as male, 56% of doctors diagnosed the patient with schizophrenia. but when the patient was described as female, only 20% of doctors diagnosed the patient with schizophrenia. so the doctors displayed gender bias.

Question 32

what can be inferred from loring and powell’s results?

Answer 32

since the differences between men and women were over-exaggerated this means that the doctors were displaying alpha bias. And so, the diagnosis given was not consistent. it varied depending on whether the patient was described as a man or women. this means that the diagnoses weren’t reliable

Question 33

what does comorbid mean?

Answer 33

if two or more illnesses occur together in the same person we say the illnesses are comorbid. from co meaning together and morbidity meaning diseased condition.

Question 34

how does comorbidity reduce the reliability of a diagnosis?

Answer 34

if a patient has a comorbid illness then doctors are more likely to ignore some of the symptoms. so, different doctors may give the same patient different diagnoses reducing the reliability of the diagnosis.

Question 35

how does comorbidity reduce the validity of a diagnosis?

Answer 35

if two illnesses are often comorbid this suggests that the criteria for diagnosing the 2 illnesses might be incorrect. they might not actually be two separate conditions. so the diagnosis might also lack validity.

Question 36

when and what did buckley decide to investigate?

Answer 36

in 2009, buckley decided to find out how many patients diagnosed with schizophrenia also had other comorbid illnesses.

Question 37

what did buckley find?

Answer 37

he found that 50% of the schizophrenia patients in his sample had also been diagnosed with depression. 47% had been diagnosed with an addiction to drugs or alcohol and 23% had been diagnosed with OCD. so buckley found that a very high proportion of individuals diagnosed with schizophrenia had a second comorbid mental disorder.

Question 38

what did buckley conclude?

Answer 38

buckley concluded that the way that doctors have divided up and categorised mental disorders might not be accurate. for instance, given how comorbid they are maybe schizophrenia and depression aren’t two separate disorders at all. they might just be part of the same illness. in other words, the criteria used to diagnose schizophrenia might lack validity.

Question 39

what does overlap mean?

Answer 39

where symptoms of schizophrenia can overlap with symptoms of other mental health disorders.

Question 40

how does symptom overlap reduce reliability of a diagnosis?

Answer 40

due to symptom overlap, it’s possible doctors won’t agree on a diagnosis. if a person suffers from delusions, low motivation and low mood, one doctor may say they have a bipolar disorder and another may say they have schizophrenia. so the diagnosis lacks reliability.

Question 41

how does symptom overlap reduce validity of a diagnosis?

Answer 41

due to symptom overlap, it’s possible the doctors might get the diagnosis wrong. they may examine a patient who experienced low mood and delusions for 6 months and diagnose them with schizophrenia when actually it turns out they had bipolar disorder. here the criteria for diagnosing schizophrenia incorrectly, identifies the patient as schizophrenic. so the diagnosis lacks validity.

Question 42

when and what did ellason and ross investigate?

Answer 42

in 1995, ellason and ross looked at patients who had been diagnosed with a condition called dissociative identity disorder. this is a condition which causes people to experience multiple different personalities.

Question 43

what happened in ellason and ross’s investigation?

Answer 43

ellason and ross compared the symptoms displayed by patients diagnosed with DID with the symptoms displayed by patients diagnosed with schizophrenia.

Question 44

what did ellason and ross find?

Answer 44

they found that the patients diagnosed with DID displayed more schizophrenic symptoms than the patients diagnosed with schizophrenia. there was a lot of symptom overlap. this could reduce the reliability of diagnosis because different doctors might look at the same symptoms and give a different diagnosis. this also reduces validity of diagnosis because the criteria used to diagnose schizophrenia doesn’t enable doctors to correctly distinguish between schizophrenia and dissociative identity disorder.