Offending paedophiles show signs of brain alterations that non-offending paedophiles do not, scientists have said. The difference between both groups appears to be that those who do not commit hands-on sexual offences display brain activity associated with greater self-control.

Research about the causes of child sexual offending have in the past identified patterns of disturbances in the temporal and prefrontal areas of the brains of offenders, linked to inappropriate behaviours and lack of inhibitory control. These disturbances seemed to increase the risk of paedophiles offending against children, but there was still too little empirical evidence to confirm this.

Scientists have also often pointed out that paedophilia in itself does not mean that people diagnosed with it (as defined by the Diagnostic and Statistical Manual of Mental Disorders) will actually molest a child.

"In the community, paedophilia is often equated with child molestation but it is evident that paedophilia is neither a necessary nor a sufficient condition to engage in child sexual offending", explains lead researcher Dr. Christian Kärgel. "This means that not all individuals with a diagnosis of paedophilia commit child sexual offences, just as many persons who sexually offend against children are not paedophiles".

In his study, published in Human Brain Mapping, he and his team investigated what in the brain distinguishes an offending paedophile from a non-offending one. The hope was that their findings would allow them to come up with interventions to prevent child sex offences.

Offending vs. non-offending

The researchers used functional magnetic resonance imaging (fMRI) to compare the behavioural performance and brain response patterns of three distinct groups of men matched for age and IQ: 40 paedophiles with history of hands-on sexual offences, 37 non-offending paedophiles, and 40 healthy non-offending controls.

While their brain was being examined in the scanner, the participants performed a response-inhibition task - known as a 'go/no-go test'. Such a test involves responding to a certain stimulus, and inhibiting that action under another stimulus - a task designed to test the attention and self-control of people. The scientists found that both the healthy controls and the non-offending paedophiles exhibited superior control, as reflected by significantly lower rate of errors during the task.

These differences were observed objectively on the brain scans. In the left posterior cingulate and the left superior frontal cortex - which play an important role in inhibition and behaviour control - there was a distinct activation pattern between non-offending and offending paedophiles. However, the differences between controls and non-offenders were minimal. The findings thus help to identify the mechanisms that make paedophiles more likely to become perpetrators.

More research will be needed in order to characterise these differences in brain activity in more detail, and paedophilia is a complex disorder which potentially involves far more than disrupted brain patterns. However, the researchers are confident that their study could pave the way to design interventions and support aimed at fostering basic inhibitory control abilities in paedophiles with a history of offending - which may help prevent additional child sex offences in the future.