Psychology Abnormality Part 2: The Biological Approach

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Medical model (also referred to as Biological Appr


  • Psychological illnesses have a physical cause (genetic, chemical, anatomical etc)
  • Treatment of psychological illness requires a physical intervention (surgery, drug treatment)

Medical model believes psychological illness can be caused by one of the following PHYSICAL causes. Use "BING" to remember these:

  • Brain Injury
  • Infections
  • Neurotransmitters
  • Genetics
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Brain Injury explanation

  • Approach considers possibility that abnormal behaviour may be caused by a problem with the structure of the brain
  • There is little evidence to support this aspect of the theory
  • Possible exceptions are a link between enlarged ventricles and some of the symptoms of schizophrenia 
  • Also a possible link between the hypothalamus and eating disorders
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Case study: Phineas Gage

Method: Whilst working on railroad, Gage (25) was preparing to blast a section of rock using explosives. Dropped tamping iron onto the rock, caused the explosive to ignite. Explosion hurled meter length iron pole point first through his left cheek, passed his left eye and exited brain and skull at top of his head. Knocked over but not believed to have lost consciousness

Results: He survived and wanted to regain his job after months of recovery. Beofre accident, was a capable and efficient foreman with a well balanced mind. No one would employ him because his personality changed to someone who was boisterous, rude and blasphemous

Conclusion: Although his accident was horrific, has taught us a great deal about the complexity of psychological processes that occur in the human brain

Evaluation: Must be careful about generalising findings as they're based on a rare case of unfortunate individual 

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Infection explanation

  • Infections can cause physical illness such as colds, flu or meningitis
  • 19th century: found that syphilis bacterium was responsible for disorder called general paresis 
  • this results in delusions and forgetfulness
  • today there is a viral theory of schizophrenia
  • some evidence suggests that influenza in the second trimester of pregnancy can lead to increased incidence of schizophrenia when the child reaches maturity
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Neurotransmitters explanation

  • Brain relies on varoius chemicals to help it communicate
  • these are called neurotransmitters
  • examples of this are adrenaline, serotonin, dopamine
  • perhaps an inbalance in these can lead to psychological disorders
  • know that LSD can cause similar symptoms to being schizophrenic and that LSD is chemically similar to brain chemical dopamine
  • clear link between brain chemistry and genes
  • Prozac: used to treat depression works by increasing the brain's levels of serotonin
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Genetic explanation

  • Put simply: mental illness is inherited from parents
  • could be shown if there is tendency for illness to run in the family
  • particular gene can be identified as being responsible for the disorder
  • We can say that there appears to be a genetic predisposition in some people to develop a particular disorder
  • e.g if one twin has schizophrenia there is on average a 42% chance their identical brother/sister will also develop the disorder
  • this suggests schizophrenia is not 100% genetic but also suggests there's a genetic element to it 
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Evaluation of the medical model

  • Model has lead to a number of widely used and effective treatments for various disorders
  • Drugs have bonus of being quick and easy to take compared to psychological treatments that can take up to months and be very costly
  • With much of research there is the problem of cause and effect
  • No psychological disorder has 100% concordance rate 
  • There are many cases of one twin having a psychological disorder and their identical twin showing no symptoms
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Further evaluation of medical model

  • Danger that if concentrate on physical definitions and physical treatments that we ignore the root of psychological illness such as poverty, stress, inequality (Szasz)
  • Szasz questions medical model's use of the term "psychological disorder"
  • if a disorder has a physical cause, then surely it should be classed as a physical illness
  • epilepsy has clear physical cause but irrational or negative beliefs, hallucionations and low mood have no obvious physical cause
  • according to Szasz should be viewed as "disorders of the mind"
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Ethics of the model (philosophical)

  • If it is decided that schizophrenia is a physical disorder caused by person's genetic makeup or structure of their brain, can't hold them responsible for their illness
  • having an illness does label that person which can be unhelpful 
  • Behaviourist approach believes that once a person has been labelled they begin to take on the characteristics of that label
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Treatments based on the medical model

If problem is caused by a physical problem, a physical procedure is required to put it right

If a problem is caused chemically than a drug might be needed to redress the balance


  • SANE estimate 25% of all drugs prescribed in the UK are designed to tackle psychological problems
  • 50 years ago, 2 new drug categories were invented enabling psychological problems to be tackled for the first time
  • these were antipsychotics designed to relieve some schizophrenia syptoms and tricyclics for depression
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  • Usually prescribed for the treatment of schizophrenia
  • main symptoms of schizophrenia: hallucinations, delusions, thought disturbances
  • all thought to be caused by brain being too sensitive to dopamine in the brain
  • Chlorpromazine prescribed to treat symptoms by blocking dopamine receptors
  • this makes the brain less sensitive
  • small side effects such as uncontrallable movements of mouth and tongue
  • Clozapine: atypical antipsychotic because it works differently to the rest.
  • first used in 1970s but withdrawn following the deaths of some patients
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  • Endogenous depression (persistent low mood that seems to have no obvious external cause) thought to be due to lowered serotonin levels
  • Serotonin is released into synapse between neurons
  • either reabsorbed or broken down by enzymes
  • they work by preventing reabsorption or by stopping the action of enzymes
  • both actions will result in serotonin hanging around longer at the synapse


  • SSRI, works by stopping serotonin being reabsorbed
  • side effects: insomnia, anxiety, sex problems, suicidal thoughts
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Evaluation of drugs

  • Most studies have shown them to be more effective than placebos
  • Drugs are even more effective if combined with psychological therapies
  • they are convenient, relatively cheap and easy to take


  • they take at least 3-4 weeks to have any noticeable effect on symptoms
  • there is undoubtedly a placebo effect
  • there is a tolerance effect requiring larger amounts of the drugs to be taken to have the same effect


  • Electroconvulsive therapy: used in emergencies to treat depression
  • patient anaesthetised and given muscle relaxant, small electric current passes through non-dominant lobe of brain for 0.5 seconds
  • results in seizure lasting up to 1 minute
  • carried out three times per week for between 1-3 weeks
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  • More extreme measures include removing or cutting brain areas
  • frontal lobotomies widely used in UK and USA to calm violent men
  • can be drastic side effects ranging from apathy to death
  • various techniques used over years to treat epilepsy
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