Biological Explanation for Schizophrenia

Question 1

What is the Genetic Explanation of Schizophrenia?

Answer 1

• Transmitted through hereditary means.
• No single ‘schizophrenic gene’ has been found - several are involved that increase vulnerability

Question 2

How are genetics studied?

Answer 2

• Family studies - look for concordance
  between relatives. Can be longitudinal
• Twin Studies - look for concordance
  between MZ & DZ twins
• Adoption studies - look for concordance
  after disentangling genes from environmental factors
• Gene mapping - look for common genetic
  variations at locations on human
  chromosomes

Question 3

What was the original Dopamine Hypothesis?

Answer 3

• Having too much dopamine can lead to schizophrenia and cause hallucinations & delusions.
• Schizophrenics are thought to have abnormally high number of D2 receptors on receiving neurons that result in more dopamine binding & more neurons firing.

Question 4

What evidence is there for the role of dopamine in creating hallucinations & delusions?

Answer 4

• Amphetamines - agonist, increases dopamine activity by stimulating nerve cells containing it - large doses cause delusions & hallucinations
• Phenothiazines - antagonist, inhibit dopamine activity & alleviate symptoms of Sz

Question 5

What is the updated Dopamine Hypothesis?

Answer 5

• High levels of dopamine in the mesolimbic (NAC) dopamine system are associated with positive symptoms
• Low levels of dopamine in the mesocortical (VTA) dopamine system are associated with negative symptoms

Question 6

What is the Neural Correlates Explanation of schizophrenia?

Answer 6

• Abnormalities within specific brain areas may be associated with schizophrenia.
• These could be caused by genetic factors or as a result of the disorder.

Question 7

What evidence is there for structural differences?

Answer 7

• Grey matter - reduced grey matter in brains of schizophrenics, enlarged ventricles found particularly in those with negative symptoms
• White matter - reduced myelination of white matter pathways

Question 8

What evidence is there for functional differences?

Answer 8

• Prefrontal cortex - impaired, main area of brain involved in planning, reasoning & judgement
• Hippocampus - anatomical changes, deficits in nerve connections with prefrontal cortex correlate with memory impairment, may influence dopamine levels