medical model

• assumption - the medical model assumes that mental illness has a physical cause and required a medical treatment
• monamine hypothesis - biochemical explanation of depression

  • noradrenaline, serotonin and dopamine are neurotransmitters who's levels are correlated with depression
  • serotonin - regulates noradrenaline and dopamine, responsible for mood and emotional memory
  • noradrenaline - controls concentration and attention
  • dopamine - lack of pleasure in previously enjoyed things
• research evidence for monamine hypothesis (depression)

  Meyer - 17 px with depression

  • compared pet scans of clinically healthy and clinically depressed px
  • Depressed had significantly higher levels of monoamine oxidase. Monoamine oxidase is an enzyme that breaks down monoamines, leading to lower levels of monoamines in the brain. 
• dopamine hypothesis - explanation of Sz

  • too many dopamine receptors and they are more sensitive than the neurotypical brain
  • more dopamine is absorbed in post synaptic neurone, leading to excess dopamine in mesolimbic (positive symptoms) and mesocortical (negative symptoms)
• research evidence for dopamine hypothesis

  • Seeman - drugs such as cocaine increase dopamine levels and increase hallucinations. A hallucinogens activate dopamine receptors which leads to vivid thoughts
• genetic explanation of depression

  • based on the logic that the more genes two people share the more similar their behaviour os; suggesting a genetic basis
  • similarity is measured in terms of correlation and concordance between people
• research evidence genetic explanation of depression

  • smoller - concordance rates for major depression in identical twins is 30-50% concordance rates of fraternal twins are 12-40%
• genetic explanation of Sz research evidence

  • mirsky - the genain quadruplets were four girls who all developed sz by 24, the girls all shared the same set of genes and there was a history of mental illness in both sides of the family
  • however, the father did abuse the girls
• brain abnormality definition of depression

  • the amygdala - drevets found that px with depression showed increased activity in this area when presented with negative stimuli (sad faces), but when presented with positive stimuli there was reduced activity. suggesting the amygdala regulations emotion which is disrupted in px with depression
• brain abnormality definition of Sz

  • 4 ventricles in the brain hold cerebrospinal fluid which provides nutrients and protection, enlarged vesicles lead to reduced grey matter
  • having reduced matter in temporal lobes may explain auditory hallucinations and in the frontal lobe may explain delusions
  • raz and raz - used meta-analysis of brain imaging studies to show enlarged vesicles in over half of those who had sz
  • treatments - surgery can be done to drain excess fluid
• key research gottesman

  aim - examine how vulnerable children of 2 parents with mental illness are to developing an illness themselves in bipolar or sz

  quasi experiment

  cohort study

  dv - if a child develops a mental disorder
• sample gottesman - 2.5 million from civil registration system in Denmark

  cross references with danish psychiatric register

  separated into 3 groups: couples who had both been admitted with sz or bp, couple were one partner had sz or bp and a group who neither parent had mental illness
• conclusions gottesman

  if both parents have a serious mental illness this signficantly increases the risk of their child developing a disorder, these results provide evidence for the genetic explanation of mental illness. thus suggesting that mental illnesss have a genetic basis

  • 2 parents with sz = 28% chance of developing sz
  • no parents with disorder = >1% chanced
• application - biological treatment of Sz

  • antipsychotics block dopamine receptors in the brain
  • less dopamine in mesolimbic and mesocortical pathways
  • reduces positive and negative symptoms