Biological explanations

• AO1 - Genetics

  -SZ tends to run in families. The risk of developing SZ is higher if you have a biological relative who has SZ
• What is the concordance rate for general population?

  -1%
• What is the concordance rate of SZ if you have a sibling with SZ ?

  • 9%
• What is the concordance rate for SZ if you have 2 parents with SZ ?

  • 46%
• What is concordance rate if you have 1 parent with SZ ?

  • 13%
• What is the concordance rate if your identical twin has SZ ?

  40.4%
• What is the concordance rate if you are adpoted and have one biological parent with SZ ?

  • 6.7%
• AO1 Genetics- Gottesman

  -Looked at concordance rate among family members and found if you have 2 parents with SZ you have a 46% concordance rate of developing it yourself

  -If 1 parent then a 13% risk, if sibling has SZ concordance rate is 9%
• AO1 Genetics - Twins

  -MZ have higher concordance rates than DZ twins. this suggests that the similarity between twins is due to genetics.

  -Joseph found that concordance rate for MZ twins was 40.4% and for DZ 7.4%
• Weakness- Methodological problems

  -Family, twin and adoption studies must be considered cautiously because they are retrospective and diagnosis may be biased by knowledge that other family member who may have been diagnosed.

  -Suggests that there may be problems of demand characteristics
• What are the 2 biological explanations for schizophrenia?

  -genetics

  -dopamine hypothesis
• Strength- Research support

  -207 children with sz parents and 104 without were investigated, sz diagnosed in 16.2% of high risk group vs 1.9% in low risk group

  -Supports idea of genetic influence

  -Research supports, found 76 genes that link to SZ, shows condition is polygenic
• Weakness- Contradictory research

  -2/3 of those with disorder have no relatives with sz, suggests explanation is oversimplified and may factors may affect diagnosis
• How does dopamine hypothesis explain schizophrenia?

  -Those with sz suggested to have excess of D2 receptors which leads to excess of dopamine in mesolimbic pathway, causing positive symptoms of sz

  -Negative symptoms are thought to be caused by deficit of dopamine in areas of prefrontal cortex
• Strengths of dopamine hypothesis- research support pet scans

  -PET scans showed lower levels of dopamine in sz compared to a control group
• Strengths of dopamine hypothesis- Research support

  -Researchers induced a dopamine deficit in prefrontal cortex of rats, found this caused cognitive impairments which could be reversed using antipsychotic medication
• Strengths of dopamine hypothesis- Real life examples

  -Those with parkinsons take medication to raise their dopamine levels, raise it by too much too quickly and they develop sz type symptoms