AO1

• Biological explanations of schizophrenia suggest that it is inherited and that there may be specific genes or neurological functions which predispose individuals to criminal behaviour.
• Schizophrenia is seen as a polygenetic disorder as there is no direct causal gene, but several which are associated with a higher risk of developing the disorder, and we call these candidate genes. In 2004, salleh identified that neuregulin 1, dysbindin, and proline dehydrogenase increase the likelihood of the disorder as they affect the production and regulation of the neurotransmitters dopamine, serotonin and glutamate used in regulating mood.
• Schizophrenia can also be resulted from mutations in parental DNA through factors like radiation, poison, or infection. This has stemmed from Brown et al in 2002 who showed a correlation with parental age (increased risk of mutation) and schizophrenia disorders.
• Neural correlates i.e. brain structures and neurotransmitters have also been suggested as a cause for schizophrenia. An example of this is that research has shown that many people with schizophrenia have larger ventricles which contain brain fluid that maintains neuron function. This means they also have smaller brain volume elsewhere e.g. frontal cortex.
• However researcher have now suggested that in the frontal cortex dopamine levels are too low causing under active neurons resulting in the negative symptoms of schizophrenia, so the model was revised.
• Another example of neural correlates as an explanation for schizophrenia is the dopamine hypothesis suggests that schizophrenia is caused when the neurons in the mesolimbic system are overactive due to an incresed level of dopamine, causing hallucinations and delusions.
• Dopamine hypothesis - schizophrenics sometimes have high dopamine levels and it is suggested by Snyder that excess dopamine can cause schizophrenic symptoms
• Davis et al updated theory as not all schizos have high dopamine levels and modern drugs (clozapine) work even though they have very little dopamine blocking activity: abnormal levels in mesolimbic = positive symptoms, mesocortical = negative symptoms