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Schizophrenia Causes Notes

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AO1 - DESCRIPTION
 Claims genetic inheritance plays a major role
 A gene must be the cause of schizophrenia and is passed onto offspring's
 Having a biological relative with schizophrenia increased your chance of developing schizophrenia A03 - EVIDENCE - Twin and Family Studies Gottesman, 2001
 Shows there is a 48% concordance for MZ twins suffering from Schizophrenia.
 Percentage decreases as relations become further
 MZ twins share 100% same genes and have the highest concordance rate = so there must be a gene involved.
- Gottesman and Shields' study is based on a sample size of only 12, which is hardly big enough for any firm conclusions to be drawn

A03 - ADOPTION STUDIES TienarI, 1991
 Assessed if schizophrenia had a biological basis or environmental basis.
 Results showed 1% of adopted schizophrenic children had no schizophrenic biological mother.
 10% of schizophrenic children had biological schizophrenic mother.
- Culture bias - study was conducted in Finland = cannot generalise to the world
- Old studies - hard to use these findings as diagnosis has changes over the years.

Advantages

Disadvantages

MZ twins are more likely to be treated as 'one' and The studies show there DZ twins are treated ad must be a gene involved two individual beings - so the environment can affect concordance. Deterministic - just because we are Lot of evidence ot 'predisposed' with our support the explanation genes does not mean we e.g. twin studies are to develop schizophrenia. No single gene has been discovered yet. The Have found 12 studies are old, therefore chromosomes with a unreliable because certain correlation in diagnosis has changed a people with schizophrenia lot over the years. MZ twins share 100%
same genes but concordance rate is just 48%.

A01 - DESCRIPTION - Dopamine Hypothesis
 Dopamine is a neurotransmitter that can increase or decrease communication between nerve neurons
 Dopamine increases communication between synapses.
 More dopamine receptors in the brains of schizophrenics
 Greater neural activity = positive symptoms of schizophrenia e.g. delusions of grandeur. AO3 - Post Mortem Iversen, 1979
- Post-mortem studies conducted by Iverson (1979) indicated that dopamine is more concentrated in the schizophrenic brain, especially in the limbic system. Antipsychotic Drugs
- Drugs that are used to treat schizophrenia are highly effective, and they work by blocking dopamine receptor sites. Additionally, the drug that is used to treat Parkinson's disease works by increasing dopamine levels in the brain. Parkinson's disease is a result of the under-production of dopamine. The drug, which is called LDOPA, is converted to dopamine, and is highly effective in reducing the symptoms associated with Parkinson's disease. However, too much of it induces schizophrenic-like symptoms in sufferers of Parkinson's disease.

Advantages Post mortem and antipsychotic evidence supports this explanation.

Disadvantages Too simplistic. Other neurotransmitters might be involved e.g. serotonin. (Breier, 1995)

Blocking receptors does not take immediate effect - a patient who takes antipsychotics has their dopamine receptor blocked immediately but the reduction in positive symptoms is not effective for at least a couple of days

Social and environmental factors are also involved It cannot be said that the explanation is exclusively biological, as environmental and social factors seem also to be able to trigger schizophrenia
- perhaps stressful events trigger excess dopamine production

Bird et al. found during post mortem scans that those who had SZ had an increase no. of D2 receptors. Evidence that SZ had high D2 receptors which means higher dopamine levels.

Amphetamines only produce positive symptom which suggests that the dopamine hypothesis is not a completed explanation. What about negative symptoms?

Amphetamines give similar symptoms When given amphetamines, which in effect increase the levels of dopamine, delusions and hallucinations are common effects, which suggest that excess dopamine neurotransmitter action produces positive symptoms

Is the increase of Dopamine levels the cause of schizophrenia ot the effect of schizophrenia - cause and effect.

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