Issues of Bias in Diagnosis

Diagnosis

• On your sheet explain how a psychologist would be confident in saying an individual has a particular mental illness.

• Mention the importance of a classification system

Bias

• A bias means that certain people or groups of people are more likely to be classed as having a particular disorder than other types of people.

The BIG question

• The issue is the cause of the bias: • Does the bias come from the system being

used to make the diagnosis (so that some groups tend to be misdiagnosed as having an illness when they don’t)?

• Or is there is an actual difference in the rates of mental illness between different groups of people (in which case, the diagnostic system is accurate)?

Cultural Bias in Diagnosis

• In Britain, certain cultural groups are more frequently diagnosed with some disorders.

• Eg people of African descent are more likely to be diagnosed with schizophrenia.

• Give TWO opposing explanations for this fact

Explaining Cultural Differences

• While this evidence suggests that a bias in diagnosis exists, it does not give us any information about the nature of this bias.

• Is there a bias in the diagnosing, OR• is there a genuine difference in the rates of

schizophrenia between those of African descent, and others?

Explaining Cultural Differences

• Over-diagnosis due to inadequate diagnostic methods

• Bias in the diagnostic tools (DSM IV and ICD) which are Western

• Bias in the Psychological Tests• Bias in the psychologist

Explaining Cultural Differences

• Genuine differences in rates of mental illness.

• Stress of being a minority? - Littlewood (1980)

• Unlikely - bias applies only to black people Littlewood & Lipsedge (1989)

• Also, higher rates among 2nd generation immigrants

Explaining Cultural Differences

• Genetic Differences? • African vulnerability to schizophrenia?• WHO – check findings p231• Littlewood(1989) Opposes – why?

Explaining Cultural Differences

• Type 1 or Type 2 error?• Type 1• Put healthy individuals in institutions• Type 2• Leave sick people out in the community

• Which is worse / more dangerous?

Explaining Cultural Differences

• Type 1 or Type 2 error?• Malgady (1996)• Denying cultural bias could lead to type 2

errors (not treating sick people)• Trying to avoid Type 2 errors leads to

Type 1 errors (locking up healthy people)• Malgady thinks this is preferable• (Complicated - but try to grasp this)

Explaining Cultural Differences

• What does Vitamin D have to do with cultural differences?

• Read the article – how does it explain the aetiology of schizophrenia?

• Where does culture come in?

Gender Bias in Diagnosis