Explanations of Schizophrenia

Question 1

Genetic factors and cause of schizophrenia?

Answer 1

1. Being genetically related to someone with schizophrenia can significantly increase a person’s chances of developing it,
2. Family and twin studies have looked at concordance rates to surmise whether schizophrenia has a genetic basis.

Question 2

Gottesman (1991), method and findings?

Answer 2

1. Reviewed about 40 twin studies and found that with identical twins there was about a 48% concordance rate, i.e. there is a 48% chance that one MZ twin will have schizophrenia if the other does,
2. With non-identical twins the concordance rate was about 17%,
3. This is significant because, if it is assumed that MZ and DZ twins share the same amount of environmental influences, it means the reason for increased concordance is the genetic difference - MZ twins share 100% of their genes, compared to DZ who share 50%.

Question 3

Evidence for genetic basis of schizophrenia?

Answer 3

1. Shields (1962) found that MZ twins raised in different families still showed around 50% concordance,
2. Adoption studies found that if children are adopted because one or both of their biological parents has schizophrenia, the chance of them developing it stays the same. It suggests that genetics are more significant than the environment.

Question 4

Evidence against a genetic explanation for schizophrenia?

Answer 4

1. No study has found a 100% concordance rate between MZ twins, so schizophrenia can’t just be caused by genes. Shared environment may cause higher concordance rates in family studies because children imitate ‘schizophrenic’ behaviours,
2. This means other factors need to be considered, e.g. biochemical or psychological factors.

Question 5

Biochemical factors as a cause for schizophrenia?

Answer 5

1. Post-mortems and PET scans have shown that people with schizophrenia have abnormally high levels of dopamine,
2. These findings led to the development of the dopamine hypothesis, which states that synapses that use dopamie as a neurotransmitter are overactive in the brains of people with schizophrenia.

Question 6

Evidence for the biochemical explanation?

Answer 6

1. Antipsychotic drugs reduce the symptoms of schizophrenia by blocking dopamine receptors, this suggests that it is the overactive dopamine receptors causing the symptoms,
2. Drugs like amphetamines, which increase dopamine function, can sometimes cause schizophrenia-like symptoms in people without schizophrenia.

Question 7

Evidence against the biochemical explanation?

Answer 7

1. Antipsychotic drugs only work on the positive symptoms of schizophrenia, e.g. hallucinations. This means increased dopamine function doesn’t explain negative symptoms like social withdrawal,
2. The link with dopamine is correlational, so it doesn’t show cause and effect. It may be that increased dopamine function is a symptom of schizophrenia, rather than a cause of it.

Question 8

What is the neurological explanation of schizophrenia?

Answer 8

1. Neural correlates, such as abnormal brain structure, could explain schizophrenia.

Question 9

Evidence for the neurological explanation?

Answer 9

1. Johnstone et al. (1976) compared the size of the ventricles in the brain of people with schizophrenia with the brains of those without schizophrenia. They found that the people with schizophrenia had enlarged ventricles, which suggests that schizophrenia is linked to reduction in the temporal and frontal lobe volume,
2. Buchsbaum’s (1990) MRI scans on the brains of people with schizophrenia found abnormalities in the prefrontal cortex.

Question 10

Evidence against the neurological explanation?

Answer 10

1. People without schizophrenia can also have enlarged ventricles, showing the relationship isn’t that simple,
2. These findings are correlational, so they don’t show cause and effect. It may be that abnormal brain structure is a symptom of schizophrenia, rather than a cause of it.

Question 11

Evolutionary explanation of schizophrenia?

Answer 11

1. Some evolutionary explanations of schizophrenia suggests that there must have been an advantage to having schizophrenia for it to remain in the population,
2. One evolutionary idea is that people diagnosed with schizophrenia today share similar characteristics to shamans of the past,
3. They were likely to lead people to split off from a group when it got too big, starting new cultures.

Question 12

Evidence for the evolutionary explanation?

Answer 12

There is such a strong genetic link to schizophrenia, that there must be some form of evolutionary explanation.

Question 13

Evidence against the evolutionary explanation of schizophrenia?

Answer 13

1. Generally discredited,
2. There is little evidence and the theory is difficult to prove.

Question 14

Schizophrenia as caused by psychological factors?

Answer 14

Three variations,
1. Family dysfunction cause,
2. Cognitive explanations,
3. Socio-cultural factors.

Question 15

The family dysfunction cause of schizophrenia?

Answer 15

1. Psychologists have suggested that conditions in dysfunctional families could cause schizophrenia,
2. One idea is that a cold and dominant ‘schizophrenogenic’ mother could cause conflict, causing schizophrenia,
3. Another idea is Bateson’s (1956) Double Bind theory, which suggested that faulty communication in families could lead to contradictory messages for children and cause schizophrenia,
4. Expressed emotion environments contain high levels of hostility and criticism towards the person with schizophrenia. EE has been found in dysfunctional families and correlates with relapse in people with schizophrenia.

Question 16

Vaughn and Leff (1976), findings in support of the expressed emotion explanation?

Answer 16

Found that people with schizophrenia were mroe likely to relapse once discharged from hospital in environments of high EE.

Question 17

Evidence for the family dysfunction explanation?

Answer 17

1. Other research investigating the role of the family on schizophrenia supports the theory of family dysfunction,
2. For example, Lidz et al. (1958) investigated families and proposed that dysfunctions such as emotionally distant parents and unequal marriages could have an impact on the children in the family, ultimately leading to schizophrenia.

Question 18

Evidence against the family dysfunction explanation?

Answer 18

1. The theory ignores the biological evidence for schizophrenia and puts the blame on the family and parents,
2. Most of the studies into the effects of family dysfunction were also retrospective - the families were only studied after the disorder had developed, and so it could have been the condition itself that had disrupted family life.

Question 19

The cognitive explanation for schizophrenia?

Answer 19

1. Cognitive psychologists argue that schizophrenia is caused by dysfunctional thought processing,
2. This leads to delusions, thought interference, language impairment, and memory problems.

Question 20

Evidence for the cognitive explanation?

Answer 20

1. Neufeld (1978) compared the cognitive processes of people with schizophrenia with a control group. Participants with schizophrenia took longer to encode stimuli and showed short-term memory problems. This suggests their ability to process information was impaired,
2. Meyer-Lindenberg et al. (2002) found that people with schizophrenia did worse in a memory and reasoning task, showing reduced activity in the area of the brain associated with this.

Question 21

Evidence against the cognitive explanation?

Answer 21

1. Biochemical research suggests that cognitive problems are caused by increased dopamine function, rather than faulty information processing,
2. So, the faulty information processing may be a result of increased dopamine levels, meaning it is a symptom, not a cause of schizophrenia,
3. Cognitive explanations don’t exclusively explain the cause of schizophrenia - they might need to be linked to biological explanations.

Question 22

Socio-cultural factors as an explanation?

Answer 22

1. The social causation hypothesis states that people with low social status are more likely to suffer from schizophrenia than people with higher social status,
2. It is thought that factors like poverty and discrimination cause high stress levels, and that this can cause schizophrenia.

Question 23

Evidence for the social-cultural factors explanation?

Answer 23

1. Harrison et al. (2001) found that people who were born in deprived areas were more likely to develop schizophrenia. This suggests that factors like poverty, unemployment, and crowding have an impact on schizophrenia.

Question 24

Evidence against the social-cultural factors explanation?

Answer 24

1. These results are correlational, so they don’t show cause and effect,
2. The social drift hypothesis suggests that there are more people with schizophrenia in deprived areas because having schizophrenia gives them a lower social status, e.g. because they might be unemployed.

Question 25

The diathesis stress model explanation?

Answer 25

1. Proposes that people who are biologically vulnerable to developing a mental disorder may be more likely to develop it if they are subjected to certain social or environmental stressors, 2. Lots of research has been conducted in this area. The fact that concordance rates in twin studies aren't 100% indicates that there does seem to be some genetic link, but that other factors must play a role as well.