sciencetech-blog

comments

Violent thugs (illustrated witha  stock image) aren't criminalised by society, but may be born that way, researchers claim

Violent thugs aren't criminalised by society, but may be born that way, researchers claim.

Scientists have identified two genes that may be associated with extremely violent behaviour.

One of them is a variant of cadherin 13 (CDH13), which is involved in neural connectivity, and has been linked to impulse control in extremely violent offenders.

Experts at the Karolinska Institute in Sweden say that the majority of violent crime is committed by a small group of anti-social, repeat offenders and set out to discover why this may be.

Previous studies have linked certain genes to violent crime, including a gene called monoamine oxidase A (MAOA) that contributes to less recycling of the neurotransmitter, dopamine.

Dopamine is a chemical released by nerve cells to send signals to other nerve cells. It plays a major role in reward-motivated behaviour.

Previous studies investigating MAOA's connection with violence have proved inconclusive.

Professor Jari Tiihonen and colleagues at the Institute analysed the genes of 895 Finnish people found guilty of criminal behaviour, organising them by the crimes they have committed.

These ranged from non-violent offences - such as drug or property crimes - to extremely violent offences, such as homicide and battery.

The researchers found a possible link between violent offences and MAOA, with the strongest association in the extremely violent offending group.

Through additional research, including a genome-wide association study, they identified a gene involved in neural connectivity - a variant of cadherin 13 (CDH13) - that has been linked to impulse control in extremely violent offenders.

The researchers identified two genes that may be associated with extremely violent behaviour. They also suggested that low dophamine recycling associated with the MAOA genotype, may result in higher aggression levels during intoxication (stock image pictured), increasing the risk of violent behaviour

'When compared to the control population, non-violent offenders were not observed to exhibit either variant to a greater degree, indicating that these genetic variants may be specific to extremely violent behaviour,' Dr Tiihonen said.

The researchers, whose findings were published in the journal Molecular Psychiatry, suggest that the low dopamine recycling, which is associated with the MAOA genotype, may result in higher aggression levels during intoxication, increasing the risk of violent behaviour.

NEUROLOGIST DISCOVERS 'DARK PATCH' INSIDE KILLLERS' BRAINS 

German neurologist Dr Gergard Roth claims to have found the 'evil patch' in the brain's central lobe (ringed) that lurks in violent criminals

Last year, a German neurologist claimed to have found the area of the brain where evil lurks in killers, rapists and robbers.

Bremen scientist Dr Gerhard Roth said the 'evil patch' lies in the brain's central lobe and shows up as a dark mass on X-rays.

He discovered it when investigating violent convicted offenders over the years for German government studies.

'We showed these people short films and measured their brain waves,' he said.

'Whenever there were brutal and squalid scenes the subjects showed no emotions. In the areas of the brain where we create compassion and sorrow, nothing happened.'

The dark mass at the front of the brain, he says, appears in all scans of people with records for criminal violence.

His research has led him to believe that some criminals have a 'genetic predisposition' to violence.

He added: 'When you look at the brain scans of hardened criminals, there are almost always severe shortcomings in the lower forehead part of the brain.

'There are cases where someone becomes criminal as a result of a tumour or an injury in that area, and after an operation to remove the tumour, that person was completely normal again.

'Or there are physiological deficits, because certain substances such as serotonin in the forebrain are not working effectively.

'But this is definitely the region of the brain where evil is formed and where it lurks.'