Brain dysfunction theory

The brain dysfunction theory of why people turn to crime emphasises the role of brain dysfunction. 

Much of the behaviour that makes us "civilised", such as self-control and maturity, are controlled by the pre-frontal cortex area of the frontal lobe. Damage to this area is thought to  result in dysfunctional behaviour such as crime. 

Various research has shown that poor functioning in the temporal lobe, such as in the hippocampus, can lead to people not learning from experience, whilst poor functioning in the amygdala has been associated with altered emotionality and outbursts of negative emotion such as anger. There has been significant association between brain dysfunction and murderers, though it is not known if there is a causality between the two and in which direction this might be. 

Study: Raine et al.

41 murderers who'd been referred to the researchers pending their NGRI pleas were involved in this study. They had a range of mental disorders including schizophrenia. There were also 41 age, gender and mental health matched controls.

Participants were injected with a tracer which attached itself to a glucose molecule to enable a PET scan to determine levels of activity in different areas of the brain. Participants were then asked to complete a 32 minute task involving concentrating on targets. 

The results showed reduced glucose metabolism in the pre-frontal cortex of the murderers' brains. The pre-frontal cortex has been associated with impulsivity, and could explain this aspect of criminality. There were also abnormal asymmetries in the limbic area. Two key areas of difference were the amygdala (which is responsible for the managing of emotions) and hippocampus (responsible for learning), which could further enhance our understanding of why some people kill whilst others do not.