A01- Biological Explanations
- Schizophrenia more common amonng biological relatives of person with schizophrenia.
- Twin Studies- Joseph pooled data shows concordance rate for MZ twins of 40% and DZ twins 7%.
- Use of blind diagnosis procedures lower concordance rate for MZ twins, but still much higher than DZ.
- Adoption study by Tienari- if biological mother schizophrenic 6.7% of adoptees also schizophrenic (2% of controls).
- Neurons that transmit dopamine fire too easily or too often, leading to symptoms of schizophrenia.
- Schizophrenics- abnormally high levels of D2 receptors.
- Evidence from large doses of amphetamines (dopamine agonist) causes hallucinations and delusions.
- Antipsychotic drugs- block dopamine and eliminate symptoms
- Parkinsons disease- treatment with L-dopa raises dopamine levels and can therefore also trigger schizo symptoms
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- Enviroments of MZ twins may be more similar that DZ twins.
- Differences in concordance rates may reflect enviromental similarity rather than role of genetic factors.
- The fact that schizophrenia runs in families may be due to factors that have nothing to do with herritability (e.g expressed emotion)
- Adopted children from schizophrenic backgrounds may be adopted by particular type of parent making conclusions difficult to draw.
- Many studies have to include 'schizophrenia spectrum disorders' to show genetic influences.
- Drugs can increase schizophrenia symptoms as neurons try to compensate. Haracz found elevated dopamine levels in post-mortems of schizos who had taken medication.
- Neuroimaging studies failed to provide convincing evidence for altered dopamine activity in schizos.
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- Provides clear predictions for example the effects of the neurons on schizo patients.
- The tests can also be proven easier or falsified easier.
- Biological theories normally arent the whole story as there may be an impact from the enviroment which isnt taken into account.
- There are methodological problems with the adoption studies as they may have not found statistical evidence without broadening the definition of schizo to include non-psychotic schizo spectrim orders. For exampke Kety found no cases of full schizo were found among cases of first degree relatives of adopted children identified with a schizo spectrum.
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- Psychodynamic view of schizophrenia - result of regression to pre-ego stage and attempts to re-establish ego control.
- Some schizophrenic symptoms reflect infatile state, other symptoms are an attempt to re-establish control.
- Further features of disorder appear as individuals attempt to understand their experiences.
- They may reject feedback from others and develop delusional beliefs.
- Prior to schizo episode, patients report twice as many stressfull life events.
- Double-blind theory- contradictory messages form parents prevent coherent construction of reality leads to schizo symptoms.
- Expressed emotion- family communication style involving criticism, hostility and emotional over-involvement.
- Leads to stress beyond impaired coping mechanisms and so schizo.
- Labelling theory- symptoms of schizo seen as deviant from rules ascribed to normal experience. Diagnostic label leads to self-fulfilling prophecy.
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- Very little evidence to support psychodynamic view of schizophrenia.
- Behaviour of parents assumed to be a key influence in development of schizophrenia but may be a consequence rather than a cause.
- Cognitive explanation supported by neurophysiological evidence e.g excess dopamine levels in the prefrontal cortex and the working memory adaptations.
- Some evidence challenges link between life events and schizophrenia. Evidence for link is only correlational not causal.
- Importance of family relationships in development of schizo shown in adoption study.
- Double-blind theory supported by Berger- schizos recalled more double-blind statements from mothers.
- Expressed emotion- has led to effective therapy for relatives.
- Schelf- 13 out of 18 studies consistent with predictions of labelling theory.
- Link supported in both retrospective and prospective studies.
- Expressed emotion effects much less common in non-individualist cultures.
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- Recognises the importance the brain can have on out behaviour and the way it makes us behave.
- Its not easy to be falisified or to be proven correct as there is no physical evidence to be gained from it.
- Culture- expressing emotion is more common in the west however non-western cultures are individualist and are less likely to blame someone else for their schizo.
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