Some psychologists say that schizophrenia can be passed down generations, meaning that some people inherit the disorder from their parents.
Twin research has consistently shown that identical twins have a greater risk of developing schizophrenia, if their twin has the disorder, than non-identical twins. Gottesman found monozygotic twins have a concordance rate of 48%, whilst dizygotic twins have a concordance rate of 17%.
Evaluation of Genetic Factors
This research shows that there is a definite correlation between genetics and the risk of developing schizophrenia.
However, no twin research has found a 100% concordance rate; therefore it is impossible the say that genes definitely cause schizophrenia, as other factors clearly have an influence.
Also, some psychologists argue that the high concordance rates found could be caused by being brought up in a family with a schizophrenic, so the child mimics the schizophrenic behaviour, rather than by genetics.
The Dopamine Hypothesis
The dopamine hypothesis says that schizophrenia is caused by an increased reaction to dopamine in the brain. This could be because there is too much of the hormone dopamine in the brain, or conversely because there is an abnormally high number of dopamine receptors in the brain. This model says the excess sensitivity to dopamine results in the brain causes the symptoms of schizophrenia.
Evaluation of the Dopamine Hypothesis
Autopsies have found an unusually high number of dopamine receptors in the brain of schizophrenics (Owen et al, 1987), however, this evidence is varied and inconclusive.
Grilly (2002) found that patients who suffered from Parkinson’s and took the drug L-dopa, which increases dopamine