schizophrenia - topic 2 - explanations of schizophrenia

Question 1

HEMSLEY’s cognitive explanation

Answer 1

• a disconnection between stored schematic knowledge and incoming new info. people with schiz get a sensory overload. They cannot differentiate. Schemas may not activate in the same was as healthy individuals. old and new memories cannot be differentiated between, therefore cannot chose between relevant and irrelevant info. consequently, internal events are misinterpreted as coming from external stimuli, this can result in hallucinations. If thoughts are automatically accessed without the individual knowing. This may cause thoughts to become ‘alien’. Simple events may be misinterpreted.

abnormalities in the hippo-campus cause the problem. This part of the brain is important in processing sensory inputs so this is a reasonable idea, but there is no consistent evidence.

Question 2

FRITH’s cognitive explanation

Answer 2

people cannot differentiate from actions from external stimuli and those that come internal intentions. suggests the hippo-campus may be involved in faulty processing. It may be dopamine is involved in this impaired processing. hallucinations and delusions arise from this faulty system. i.e. non-speech sounds may interpreted as speech. Frith found evidence in a change in blood flow in schizophrenic individuals when asked to do a particular task.

Question 3

Evaluating FRITH and HEMSLEY

Answer 3

• neither take account of environmental factors. this makes it a reductionist approach. this complex disorder doesn’t lend itself to simple explanation.
• they explain the deficits which are seen in cognitive processing but do not explain how these deficits arise.

Question 4

Genetic explanation

Answer 4

schizophrenia appears to run in families. assume a genetic link, however, families do also tend to share environments.

Question 5

Family studies

Answer 5

-risk of developing schizophrenia is approx. 1% in the general population and approx 10% higher if an individual has a sibling/child with schizophrenia. (Gottesman)
eval: fam studies usually retrospective and study groups post-diagnosis. may impact reliability.
hard to seperate genetics and environment

Question 6

KETY’s family study

Answer 6

• 207 offspring of mothers diag. with schiz. (high risk group)
• all matched with other children in a low risk group
• schiz was diagnosed in 16.2% of high risk group and 1.9% of low risk group.

evaluation:
prospective
matching relevant variables: socio-economic status, urban living environment, gender, age
genes vs environment, cannot separate the two if mother lives with child
reliability of diagnosis: mothers had been diagnosed before introduction of modern classification systems

Question 7

twin studies

Answer 7

likelihood of both twins having schizophrenia = concordance rate
Gottesman: 40 European studies over a 30 year period. average concordance rate of MZ twins= 48% DZ twins = 17%
Gottestman and Shileds: of 12 MZ twins raised apart 7 were studied to find a 58% concordance rate.

evaluation:

• small scale, hard to find ppts
• until recently DZ twins mistaken for MZ twins, caused error in results
• hard to compare studies if different diagnostic critera were used
• different methods of concordance rate calculation

Question 8

adoption studies

Answer 8

• researchers look at individuals who were born by schizophrenic parents then adopted by healthy individuals.
• KETY et al: a higher rate of schizophrenia in biological relatives of children who have schizophrenia. (20.3% compared to adoptive relatives (5.3%) - ultimately suggests genetic component in schizophrenia

evaluation:
-some studies fail to identify interactions between factors. WAHLBERG identified significant interaction between deviant means of communication from adoptive parents and the development of schiz. suggests genetic make-up causes increased sensitivity to factors in the environment.

Question 9

evaluating the genetic explanation

Answer 9

• convincing that genetics is a risk factor for schizophrenia.
• however, other factors must play a role.
• no confirmed gene involved, more than one gene involved in schizophrenia as symptoms are so diverse.

Question 10

Biochemical explanation

Answer 10

• chemicals that transmit messages from one nerve cell to another = neurotransmitters
• 3 mains biochemical systesms that may be involved in schizophrenia; dopamine, serotonin,noradrenaline
• dopamine hypothesis:
• schiz. caused by dopamine activity increasing
• realised when drugs such as amphetamines and l-dopa cause a similar paranoid state by increasing dopamine levels in the brain
• phenothiazines (antipsychotic) block dopamine activity relieving major symptoms
• some studies have not shown consistent evidence so the hypothesis has been modified to suggest that it is not increased dopamine levels but in fact receptors on nerve cells may be extra sensitive to dopamine.
• SEEMAN using PET scans has shown that individuals with schiz. have a much denser network of certain dopamine receptors

evaluation:
- post-mortem studies: show increase levels of dopamine and dopamine receptors in schizophrenics.
- Issue of causality: does schiz. cause the changes or do the changes cause schiz. anti-psychotics may also impact the brain
- drugs acting on the brains dopamine system relieve many of symptoms. however, not everyone reacts positively to such drugs, suggesting other systems are involved

Question 11

psychosocial explanations

Answer 11

-schizophrenia is more common in lower socio-economic classes/
-social drift hypothesis: schiz. sufferers have more trouble maintaining jobs and relationships, may be why often found in lower in the social hierarchy
-people from other countries and settle in to new environments have a higher chance of being diagnosed. afro-carribean population has a higher diagnostic rate than the rest of the indigenous population. possible racial bias?
-Expressed Emotion: going into homes of high EE is more likely to cause relapse.
EE: high levels of critical comments, hostility and emotional over involvement. assessed using semi-structured interview.
VAUGHAN and LAFF: individuals with schiz. sent home to high EE homes were significantly more likely to relapse
evaluation of EE:
-studies are correlation
-high EE levels are found in homes of individuals with depression, not a defining characteristic of schiz.
-has practical use