Background

• Biochemical explanations for mental illness


  • Monoamine hypothesis (depression)
  • Dopamine hypothesis (schizophrenia)
• Monoamine hypothesis


  Depression is caused by a drop in serotonin levels, which disrupts the regulation of dopamine and noradrenaline
• Dopamine hypothesis


  Schizophrenia is caused by high levels of dopamine in the lower regions of the brain, leading to positive symptoms, or low levels in the prefrontal cortex, leading to negative symptoms
• Biochemical explanations see mental illness as a result of abnormal neurotransmitter levels or activity
• Genetic explanations for mental illness

  • Twin studies
  • Brain abnormalities
• Twin studies


  Higher concordance rates for schizophrenia in monozygotic twins compared to dizygotic twins suggests a genetic explanation, but environmental factors also play a role
• Brain abnormalities


  Structural deficits in the frontal lobes linked to depression, and functional deficits in the left hemisphere and ventral striatum linked to schizophrenia
• Mental illness can be caused by abnormalities in the structure or function of the brain