Scientists on trail of the killer instinct

Scientists have begun to use advanced brain imaging technology to look for biological differences between the normal brain and the psychopathic one.

Profound social issues will be raised if researchers find that changes in the brain contribute to a person becoming a killer, according to a report published this morning in the journal, Nature.

Many psychiatrists now accept that some people who choose a life of crime suffer from a condition known as psychopathy. A growing number of experts put this "choice" down to biological rather than environmental or social factors.

"More and more data are leading to the conclusion that psychopathy has a biological basis, and has many features of a disease," according to Dr Sabine Herpertz, a psychiatrist at the RWTH-Aachen University in Germany.

Scientists have long sought a "reason" why an apparently normal person might suddenly commit horrible crimes. They are now using technology to record electrical activity and blood flow inside the brain, searching for any telltale signs of psychopathy.

One US group has found that damage to a decision-making brain region called the orbitofrontal cortex leaves the person aggressive and with severe social behavioural problems.

A British team has pinpointed another possible area, the amygdala, which processes emotion and the fear response. Amygdala dysfunction could explain the lack of fear and empathy in psychopaths.