The Dopamine Hypothesis

• Hyperdopaminergia in the sub cortex

  • Claims that high levels in the neurotransmitter dopamine in the sub cortex (central areas of the brain, particularly the Mesolithic pathway) are associated with mainly the positive symptoms of schizophrenia
  • Schizophrenics are thought to have abnormally high numbers of dopamine of receptors on postsynaptic neurons = more dopamine binding and thus, more neurons firing and thus, increasing the level of dopamine
• Dopamine binding - Dopamine is sticking/attaching to each other so when reaching receptors, more uptake is occuring
• Hypodopaminergia in the cortex

  • Proposes that whilst the positive symptoms of dopamine may be explained by an excess of dopamine in the sub cortex, particularly the Mesolimbic pathway, the negative symptoms may actually be associated with decreased levels of dopamine in the prefrontal cortex.
• What do dopamine antagonists like amphetamines do to schizophrenia?

  They worsen symptoms and can induce them
• How do dopamine levels relate to schizophrenia according to Curran et al (2004)?

  Heightened dopamine influences schizophrenia severity
• What did Lindstroem et al (1999) find about dopamine production in schizophrenics?

  They uptake chemicals for dopamine faster
• What does the research by Lindstroem et al (1999) support regarding dopamine in schizophrenia?

  Schizophrenics produce more dopamine
• What is associated with positive symptoms of schizophrenia according to Davis et al (1991)?

  High levels of dopamine in the Mesolimbic system
• What is associated with negative symptoms of schizophrenia according to Davis et al (1991)?

  High levels of dopamine in the mesocortical system
• What role does glutamate play in schizophrenia according to Davis et al (1991)?

  Reduced function of glutamate is observed
• What are the key findings of the studies on dopamine and schizophrenia?

  • Curran et al (2004): Dopamine antagonists worsen symptoms
  • Lindstroem et al (1999): Schizophrenics uptake dopamine chemicals faster
  • Davis et al (1991):
  • High dopamine in Mesolimbic = positive symptoms
  • High dopamine in mesocortical = negative symptoms
  • Reduced glutamate function in schizophrenics