Schizophrenia

Question 1

What two main classification systems are in use for diagnosing schizophrenia

Answer 1

DSM-5
ICD-11

Question 2

what do they require for a diagnosis

Answer 2

DSM-5 = one positive symptom
ICD-11 = two or more negative symptoms

Question 3

what is schizophrenia

Answer 3

a severe mental illness where contact with reality and insight are impaired, an example of psychosis

Question 4

What are positive symptoms

Answer 4

additional experiences beyond ordinary

Question 5

examples of positive symptoms

Answer 5

Hallucinations = unreal perceptions of the environment, sensory experiences e.g hearing voices or seeing people

Delusions = irrational beliefs that seem real to the person e.g believing they are Jesus

Disorganised speech = result of abnormal thought processes where individual has problem organising thoughts or speech

Grossly disorganised or catatonic behaviour = lack of motivation to start or complete a task, leads to difficulties in daily living and can decrease personal hygenie

Question 6

What is a negative symptom?

Answer 6

reduction or loss of normal functions
they reduce ability to manage everyday activites

Question 7

Examples of negative symptoms

Answer 7

speech poverty = reduction in fluency and quality

Avolition = reduction of intrests and desires and inability to start tasks

Affective flattening = reduction in the range of intensity of emotional expression e.g facial expression

Anhedonia = loss of interest or pleasure in almost all activities

Question 8

What is diagnostic reliability?

Answer 8

Clinicans must be able to reach the same conclusions at two different points in time (test-retest reliability) or

different clincians must reach the same conclusions (inter-rater reliability)

Question 9

evidence of diagnostic reliability

Answer 9

Osorio et al reported excellent relibaility for DSM-5 schizophrenia reliability
inter-rater reliability +0.97
test-retest reliability +0.92

Question 10

AO3 - lack of inter-rater reliability

Answer 10

Research suggests significant variation between countries when it came to diagnosing

Copeland gave US and British psychologists description of a paitent
60% US compared to 2% British gave the same diagnosis

Question 11

AO3 - unreliable symptoms

Answer 11

for diagnosis only one of the symptoms is required if ‘delusions are bizzare’
50 psychatrists were asked to differentiate between ‘biazzare’ and ‘non biazzare’ delusions, produced inter-rater reliablity correlations of only 0.40
suggests central diagnostic requirement lacks sufficient reliability = cannot be an accurate method

Question 12

Why does diagnosis of schizophrenia have low validity

Answer 12

• gender bias
• symptom overlap
• co-morbidity
• criteria validity

Question 13

Gender bias in diagnosing schizophrenia

Answer 13

occurs when accuracy of diagnosis is dependent on gender of individual

men are diagnosed with schizophrenia more often than women

diagnostic catogeries may be baised to pathologising one gender rather than the other
= some women miss out on treatmeant due to a lack of diagnosing

Question 14

Symptom overlap and Co-morbidity/ AO3 for conseuquences of co-morbitidy

Answer 14

Many symptoms of S are also found in other disorders

most who are diagnosed with S have symptoms of other disorders which they could be diagnosed with it

meta-analysis found 12% of paitents w S also fulfilled the diagnostic critera for OCD and 25% displayed significant OCD symptoms

Question 15

AO3 - validity of diagnostic manuals

Answer 15

Cheniaux et al (2009)
two psychatrists independently asses the same 100 clients
68 diagnosed with schizophrenia with ICD and 39 with DSM
means S is either over or under diagnosed depending on the criteria you use
suggests criterion validity is low

Question 16

AO3 - research support for gender bias

Answer 16

Loring and Powell

Male and female psychatrists read two cases of paitents behaviour
If paitents described as male or no info about gender, 56% gave diagnosis
when female only 20%
this gender bias was not evident amoung femal psychatrists, suggesting diagnosis also influenced by gender of clincian

Question 17

The dopamine hypothesis

Answer 17

• excess of dopamine in certain regions of the brain is associated with the positive symptoms of schizophrenia (hyperdopaminergia)
• ‘normal’ individuals exposed to large doses of dopamine relasing drugs develop the characteristic symptoms of a schizophrenic episode
• antipsychotic drugs block the activity of dopamine, eliminating symptoms such as hallucinations

Question 18

The revised dopamine hypothesis

Answer 18

• Davis and Kahn proposed that positive symptoms are caused by excess of dopamine in subcorticol areas of the brain
• negative and cognitive symptoms caused by a deficit of dopamine in prefrontal cortex

Question 19

AO3 - evidence supporting dopamine hypothesis

Answer 19

• successful treatment using drugs that change levels of dopamine in brain
• concluded that all the anti-psychotic drugs tested in their meta-analysis were significantly more effective than the placebo in treatement of + and - symptoms

Question 20

AO3 - challenges to the dopamine hypothesis

Answer 20

• Noll claims strong evidence against the orginal and revised hypothesis
• antipsychotic drugs do not alleviate hallucinations and delusions in 1/3 of people
• in some people hallucinations and delusions present despite normal dopamine levels
• suggests that rather than dopamine being the sole cause, other neurotransmitters may also produce symptoms

Question 21

Genetic factors - concordance

Answer 21

family studies
- show more common in biological relatives of a perosn with S
- closer degree of genetic relatedness, greater the risk
- Gottesman children with two S parents had concordance of 46%

twin studies
- Joesph pooled data and found concordance MZ 40.4% and DZ 7.4

adoption studies
- Tienari et al found of 164 adoptees whose bio mothers diagnosed with S, 11 also recieved a diagnosis compared to 4 control adoptees (born to non-S mothers)

Question 22

Genetic factors - candidate genes

Answer 22

• S is polygenic - requires a number of factors to work in combination
• so many genes have been identifies
• Ripke et a carried out a genome-wide study and found 108 seperate genetic variations associated with increased risk

Question 23

AO3 - MZ twins have similar environments

Answer 23

• assumption that MZ and DZ twins environments are equivalent, therefore assumes differences are down to genetic factors
• however MZ experience more similar environments and treated more similar
• suggests that differences in concordance rates between MZ and DZ reflect environmental differences as well as genetic

Question 24

AO3 - strong evidence for genetic basis

Answer 24

• family studies show increased risk with genetic similarity
• Hilker et al found MZ 33% and DZ 7%
• adoption studies show that biological children with parents S are at greater risk even if they grow up in an adoptive family
• shows some people are more vulnerable to S because of genes

Question 25

Neural correlates

Answer 25

• pre-frontal cortex - involved in executive control and is impaired in S patients
• the hippocampus - deficits in the nerve connections between hippocampus and PFC
• grey matter - reduced volume, many with - symptoms have enlarged ventricles = result of loss of grey matter
• white matter - reduced myelination of white matter pathways

Question 26

AO3 - support for the influene of grey matter

Answer 26

• meta analysis
• paitents w S compared to normal showed higher reduction in grey matter volume over time
• loss of grey matter was especially active in the first stages of disease consistent with the early onset on S

Question 27

AO3 - implications for treatment

Answer 27

• early intervention may stop development
• american hospital uses neuroimaging to predict who will develop
• with a better understanding of how S develops, researchers can detect loss of brain tissue early and treat at-risk paitents before