explanation of schizophrenia

• What is the biological explanation of schizophrenia primarily focused on?

  Dopamine hypothesis and genetics
• How do neurotransmitters work in the context of schizophrenia?

  They are involved in chemical processes that differ in the brains of people with schizophrenia
• What are the biochemical factors associated with schizophrenia?

  • Higher levels of dopamine in the brain
  • Increased dopamine in the mesolimbic system leads to positive symptoms
  • Increased dopamine in the mesocortical system leads to negative symptoms
• What does the dopamine hypothesis suggest about dopamine levels in schizophrenia?

  It suggests that higher levels of dopamine lead to symptoms of schizophrenia
• Discovered when:​

  • Giving certain drugs that blocked ​

  these receptors and reduced the ​

  symptoms Giving certain drugs that increase dopamine levels that produced symptoms very similar to paranoid schizophrenia.​
• Evidence for the dopamine hypothesis:

  • Evidence for this dopamine hypothesis comes mainly from studies of drugs, in particular amphetamines (speed), which are dopamine agonists (that is, they prevent the breakdown of dopamine and so lead to an increase in levels). ​
  • When amphetamines are given in large quantities they lead to delusions and hallucinations similar to those in schizophrenia. When they are given to patients suffering from schizophrenia their symptoms get worse.#
• What is a limitation of the dopamine hypothesis in its original form regarding schizophrenia?

  It only explains the positive symptoms of schizophrenia, not the negative symptoms.
• Why do we expect negative symptoms of schizophrenia to be associated with low levels of dopamine?

  Because negative symptoms are not explained by raised dopamine levels.
• What is the implication of some drugs that are dopamine agonists not inducing schizophrenia symptoms?

  It suggests that schizophrenia is not solely related to raised dopamine levels.
• What is a finding regarding dopamine abnormalities in people with schizophrenia?

  Dopamine abnormalities are not found in all people with schizophrenia.
• How do phenothiazines relate to the treatment of schizophrenia?

  They only work on some people with schizophrenia.
• How long can treatment for schizophrenia take to show effects?

  Treatment can take several days to show effects.
• What is a characteristic of the dopamine hypothesis in relation to its approach to schizophrenia?

  It is considered reductionist.
• Strengths of the theory:

  • Phenothiazines are used to treat people with schizophrenia, these drugs block the receptor sites, reducing dopamine action – gives validity to the theory, if a theory can lead to effective treatment.​
  • Brain structure can have a link to dopamine hypothesis. Those with schizophrenia have different brain structures, such as grey matter, from an early age which can lead to an increase in dopamine sensitivity.
• Gene C4- Pinpointing the exact genes responsible has not been easy: schizophrenia seems to involve several genes rather than just one. However, a recent study has narrowed down this search.​​Sekar et al. (2016) analysed 100,000 human DNA samples from 30 different countries. They identified a gene called complement component 4 (C4), which is part of the immune system.​​Genetic analysis of 65,000 people found that those who had particular forms of the C4 gene showed higher risk of developing schizophrenia.
• ​

  • Recognising the genetic aspect of schizophrenia is important for people with a history of schizophrenia in their families. It alerts them that they are at higher risk of developing the disorder themselves. - Avoid stressful occupations. – can be recognised early if you look for it​
  • Drugs (use based on Dopamine hyp) only deal with positive symptoms and have nasty side-effects of their own. C$ research could give treatments to stop the issue happening in the first place​
  • We needs synaptic pruning – it would need a VERY fine balance
• What is L-DOPA used for in the brain?

  1. DOPA is a building block for dopamine production.
• What does the mixed evidence for the dopamine hypothesis suggest?

  It suggests that while dopamine levels may be higher in people with schizophrenia, the relationship is not fully understood.
• Gottsman and sheilds: Used the Maudsley twin register and found 58% (7/12 MZ twins reared apart) were concordant for schizophrenia
• What is the global prevalence of schizophrenia?

  About 1%
• Why does the consistent prevalence of schizophrenia worldwide support a biological view?

  Because prevalence does not vary with environment
• How does the risk of developing schizophrenia change with genetic relatedness?

  The risk rises with the degree of genetic relatedness
• What is the risk of developing schizophrenia for a spouse of someone with the disorder?

  1%
• Who conducted a study involving L-DOPA and schizophrenia in 1999?

  Lindstroem et al. conducted the study.
• What is the risk of developing schizophrenia for a child of someone with the disorder?

  13%
• What is the risk of developing schizophrenia for a dizygotic (DZ) twin of someone with the disorder?

  17%
• What is the risk of developing schizophrenia for a monozygotic (MZ) twin of someone with the disorder?

  48%
• What did Kendler et al (1985) find regarding first-degree relatives of those with schizophrenia?

  They are 18 times more at risk than the general population
• What is the concordance rate of schizophrenia for children with both parents suffering from the disorder?

  46%
• What evidence supports the hereditary nature of schizophrenia?

  • Risk increases with genetic relatedness
  • Higher risk for first-degree relatives
  • High concordance rates in twins
• How does the degree of genetic relatedness affect the chance of developing schizophrenia?

  The closer the genetic relationship, the greater the chance of developing the disorder
• What was the method used by Lindstroem et al. to study L-DOPA in schizophrenia?

  They used PET scanning to trace the L-DOPA in the brain.
• What process does the human brain undergo during adolescence?

  Synapse pruning
• Why is synapse pruning considered a good thing during adolescence?

  It helps the brain 'prune' under-used or damaged connections to make space for new ones
• What does the phrase "use it or lose it" refer to in the context of the brain?

  It refers to the brain's tendency to eliminate under-used connections during synapse pruning
• What role does C4 play in the brain?

  C4 plays a role in pruning synapses
• What could excessive pruning of synapses lead to?

  It could lead to symptoms seen in schizophrenia
• What was observed in test mice with increased levels of C4 activity?

  They lost more brain cells as they matured
• Why do schizophrenia symptoms appear after adolescence?

  Because excessive synapse pruning occurs during this period
• How does the cerebral cortex of people with schizophrenia compare to that of healthy individuals?


  People with schizophrenia have a thinner cerebral cortex with fewer synapses