Medical model (also referred to as biological)

The medical model views mental illness much as it views physical illness and hence refer to psychological problems as ‘illness.’  Of all the models it is the most scientific and hence the most well respected. 

1.  Assumptions

·         Psychological illnesses have a physical cause (genetic, chemical, anatomical etc.)

·         Treatment of psychological illness will require a physical intervention (surgery or drug treatment for example).

The medical model believes that psychological illness can be caused by one of the following physical causes:

2. Explanations

Genetic

Put simply, mental illness is inherited from parents.  This could be shown if there is a tendency for an illness to run in the family or if a particular gene can be identified as being responsible for the disorder. 

Usual methods of study include family, twin or adoption studies that look for links between individuals with a similar genetic make up.  However, this is psychology, and nothing is ever that simple!  At best what we can say is there appears to be a genetic predisposition in some people to develop a particular disorder.  For example if one twin has schizophrenia there is on average about a 42% chance that their identical brother or sister will also develop the disorder.  This obviously suggests that schizophrenia is not 100% genetic, but it also suggests that there is a genetic element to it.

Biochemistry

The brain relies on various chemicals to help it communicate, these are called neurotransmitters.  Examples include adrenalin, serotonin and dopamine.  Perhaps an imbalance in these chemicals can lead to psychological disorders.  We know that LSD can cause similar symptoms to being schizophrenic and we know that LSD is chemically similar to the brain chemical dopamine.  There is a clear link between brain chemistry and genes.  It seems reasonable to assume that an abnormal brain chemistry is an inherited characteristic.

Dopamine hypothesis of schizophrenia

It appears that the schizophrenic brain is overly sensitive to this neurotransmitter so as a result messages get passed on that would be blocked out in a ‘normal’ brain.  Drugs such as chlorpromazine, used to treat some of the symptoms of schizophrenia make the brain less sensitive to dopamine.

Prozac, used to treat depression appears to work by increasing the brain’s levels of serotonin.

Neuroanatomy

This approach considers the possibility that abnormal behaviour may be caused by a problem with the structure of the brain.  We know that brain damage can cause catastrophic alterations to performance and behaviour, for example Clive Wearing or Phineas Gage.  But can more subtle alterations to structure lead to mental illness?

Generally speaking there is less evidence to support this aspect of the theory.  Possible exceptions are a link between enlarged ventricles (fluid filled chambers in the brain) and some of the symptoms of schizophrenia, and a possible link between the hypothalamus (yes again) and eating disorders. 

Infection

Infections can clearly cause physical illness such as colds, flu, meningitis etc., but can they cause psychological illness?  In the 19^th century it was found that the syphilis bacterium was responsible for a disorder known as general paresis which resulted in delusions and forgetfulness.  Today there is a viral theory of schizophrenia.  Some evidence has suggested that influenza during the middle section of pregnancy (second trimester), can lead to an increased incidence of schizophrenia when the child reaches maturity.

Evaluation of the medical model

The model has lead to a number of widely used and effective treatments for various disorders.  Drugs have the added bonus of being quick and easy to take compared to psychological treatments that can take months and be very costly.

With much of the research there is the problem of cause and effect.  For example if we carry out a post mortem on a schizophrenic and find enlarged ventricles, can we be certain that these caused the schizophrenia?  Perhaps the schizophrenia has caused enlargement of the ventricles. 

No psychological disorder has a 100% concordance rate when MZ twins are compared.  There are many cases of one twin having a psychological disorder and their identical twin showing no symptoms. 

‘Treatment aetiology fallacy.’  Sounds complicated!!  You have a headache so you take aspirin.  As if by magic the headache disappears.  Conclusion lack of aspirin must have caused the headache!   Unlikely, but that is what the medical model suggests time and time again with its research.  Prozac increases the levels of serotonin therefore lack of serotonin  must have been the cause of the depression.

There is the danger that if we concentrate on physical definitions and physical treatments that we ignore the root causes of psychological illness such as poverty, stress and inequality (Szasz).  Szasz questions the 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 a clear physical cause but irrational or negative beliefs, hallucinations and low mood have no such obvious physical cause and according to Szasz should be viewed as ‘disorders of the mind’ and ruling out the medical model.   

Ethics of the medical model (philosophical)

If we decide that schizophrenia is a physical disorder caused by a person’s genetic make up or the structure of their brain, then can we hold them responsible for their illness any more than for example we can blame a diabetic for their inability to control their blood sugar levels?  If that is the case then what happens on those rare occasions when a schizophrenic harms someone?  Surely the person cannot be blamed!

The flip side to this however is that it does label people, this can be unhelpful, particularly since generally speaking schizophrenics do not have a good press.  Come to think of it sometimes neither do depressives (think of the appalling treatment of Frank Bruno by the Sun!).  Additionally, the behaviourist approach (considered later) believes that once a person has been labelled they begin to take on the characteristics of that label.  Others too look for tell-tale symptoms and start to see normal behaviours as being odd,  Read about the ‘engages in writing behaviour’ in Rosenhan’s classic study.   

In a similar vein, if you know that a particular disorder is partly genetic and there is a history of it in the family then it is only natural that you will start to look for signs of it in your own behaviour.  We have a self-fulfilling prophecy!

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