The Biological Model of Abnormality

The biological model assumes psychological disorders are physical illnesses

• Genetics - faulty genes are known to cause some diseases that have psychological effects e.g. huntingtons. 
• Neurotransmitters - Too much or too little of particular neaurotransmitters may produce psychological disorders e.g. increased dopamine leads to schizophrenia and drugs can cause this. 
• Infection - Disorders may be caused by infection. General paresis is a condition involving delusions and mood swings, leading to paralysis and death. It is caused by syphilis and can now be treated. 
• Brain Injury - Accidental brain damage may produce psychological disorders e.g. Phineas Gage developed impulsiveness and disorganisation, could not plan ahead and had a different personality. 

Research has been done into the genetic basis of schizophrenia

Twin Studies

Gottesman

Method: Carried out a meta analysis of approximately 40 twin studies

Results: It was found that having an identical twin with schizophrenia gave you a 48% chance of developing the condition. This reduced to 17% in non identical twins. 

Conclusion: Schizophrenia has a strong genetic basis

Evaluation: It was a field study so had high ecological validity. Shows another factor can also be involved as only 50% developed the disorder. This may come down to…