Classification and diagnosis of schizophenia

Question 1

How many people have SZ

Answer 1

1% of the population have the disorder, onset of first symptoms is around 15-45 years. Men are more likely to develop the disorder, with males also having an earlier onset

Question 2

What are positive symptoms

Answer 2

experiences that are in addition to normal experiences

Question 3

What are negative symptoms

Answer 3

loss of normal experiences and abilities

Question 4

What manual is most often used for SZ classification

Answer 4

DSM (diagnostic and statistical manual) often used for classification.

ICD (International classification of Disease) can also be used.

Two of the following symptoms need to be present for at least a month, one being positive

Question 5

What are two positive symptoms of SZ

Answer 5

hallucinations and delusions

Question 6

What are hallucinations

Answer 6

additional sensory experiences such as seeing distortions in objects that look like faces, or hearing critical voices

Question 7

What are delusions

Answer 7

irrational beliefs about themselves or the world.
Eg feelings of persecution or grandeur

Question 8

What are two negative symptoms

Answer 8

avolition and speech poverty

Question 9

What is avolition

Answer 9

lack of purposeful, willed behaviour, no energy, sociability affection or attempt at personal hygiene, generally apathetic

Question 10

What is speech poverty

Answer 10

brief verbal communication style. Loss of quality and quantity of verbal responses

Question 11

Reliability

Answer 11

how consistent the results are using the same measuring tool, so if we measure again we get the same results

Question 12

validity

Answer 12

are measurements made correctly referring to something real in the world

so in SZ that a person really has the disorder when diagnosed, or that SZ is a real disorder with clear and unique symptoms

Question 13

What is inter-rater reliability

Answer 13

measure how two observers agree
eg giving same diagnosis

Question 14

What is test-retest reliability

Answer 14

the same doctor giving the same diagnosis overtime with the same symptoms

Question 15

Reliability strength SZ

Answer 15

Beck in a review of 153 patients who had been diagnosed by multiple doctors found only a 54% concordance rate between the doctors assessments, suggesting low inter-rater reliability in diagnosis of SZ. This also suggests many people have been diagnosed incorrectly, potentially having inappropriate treatments

Question 16

What could affect validity

Answer 16

comorbidity, symptom overlap, gender, gender bias, culture, culture bias

Question 17

Why is validity affected by comorbidity

Answer 17

SZ is often diagnosed with other disorders. Could be leading to inaccurate diagnosis of SZ, when it could be a severe case of depression. Or as these diagnosis often occur together they are perhaps not separate disorders

Question 18

Comorbidity strength

Answer 18

Buckly found the following comorbidity rates with SZ. Depression 50%, drug abuse 47%, PTSD 29%, OCD 23%. As well as complicating treatment plans, this suggests that the original diagnosis of SZ may be in error if the disorders share symptoms

Question 19

Why is validity affected by symptom overlap

Answer 19

bipolar disorder also has hallucinations and delusions as a symptom (positive). If the two disorders are so similar it may be they arent actually distinct and should be redefined

Question 20

Why is validity affected by gender

Answer 20

Over a lifetime men and women are equally likely to be diagnosed, however mens average age of. diagnosis is 25, 5 years sooner han women. Men are more likely to have drug abuse as a comorbidity, have worse social functioning and suffer negative symptoms. Women are more likely to display positive symptoms

Question 21

Why is validity affected by gender bias

Answer 21

It is suggested that womens experiences of SZ is taken less seriously and under-diagnosed compared to men. Cotton suggests this is due to womens better social coping strategies leading to being less likely to seek treatment

Question 22

Why is validity affected by culture

Answer 22

People with Afro-Caribbean heritage in the UK and African Americans are up to 9 times more likely to be diagnosed with SZ compared to 1% of the general population

Question 23

Why is validity affected by culture bias

Answer 23

As schizophrenia rates are also 1% in countries of origin, the rise in diagnosis rates are likely due to cultural bias. Or Fernando suggests ‘category failure’, western definitions of mental illness are applied to non-western cultures. A specific example is how hearing voices of angels would be defined as an auditory hallucination in the UK but a religious experience in the west indies

Question 24

Strength of diagnosis bias in gender and race

Answer 24

Loring and Pwell sent 290 psychiatrists two identical case studies, the psychiatrists however the gender and race of the case studies were changed to either a white male, black male, white female or black female or no gender or race disclosed. The researchers found over diagnosis of the black case studies and under diagnosis of the female case studies. The most accurate diagnosis was when the gender and race of the psychiatrist was the same as the case study. Suggesting the existence of both gender and culture bias in psychiatrists diagnosis of SZ