From Attention to Behavior: Increasing Behavioral Inhibition

This project will investigate if transcranial direct current stimulation can be used as treatment for Pedophilia. Treatment efficacy will be evaluated with behavioral tasks and the recording of eye-movement.

Pedophilia is an important motivation for sexual offenses involving children, including child pornography and sexual contacts with children (henceforth, pedosexual behavior). Indeed, approximately half of individuals convicted for sexual offenses against children have a Pedophilic disorder and offenders with a Pedophilic disorder are much more likely to sexually reoffend.

A promising line of research has examined the neurocognitive basis of pedophilia. Pedophilic individuals display altered activity in the dorsolateral prefrontal cortex (dlPFC) when attending to child-related stimuli. This brain area is involved in the cognitive control of sexual arousal. Transcranial Direct Current Stimulation (tDCS) has been examined as a non-invasive method to increase activity in the dlPCF, ultimately increasing inhibitory control over impulses. Accumulating evidence also shows that individuals have an attentional bias towards sexually preferred stimuli. These attentional processes can be investigated by recording eye movements. Early automatic eye movements are particularly relevant in discriminating individuals with pedophilia from those without pedophilia.

The proposed study will examine the effects of tDCS over the dlPFC of pedophilic individuals and healthy controls, while they complete a task requiring controlled attention to virtual (computer-generated) images of children and adults. In two separate sessions, participants will be randomly assigned to an active and a placebo (sham) tDCS condition. Eye movements will be recorded during the task.

The investigators expect to observe a conflict between automatic and controlled attention when participants are presented with their sexually preferred stimuli. Specifically, the investigators expect pedophiles to show an attentional bias towards virtual child stimuli. The investigators predict that the attentional conflict will be reduced when tDCS is applied, compared to the sham condition. If the attentional bias is a key cognitive feature of sexual interest, the investigators expect to measure changes in reported or indirectly assessed sexual preferences.

Eligibility Criteria:
Inclusion Criteria:

Patients

* Diagnosed with pedophilia (further psychiatric illnesses possible)
* Sufficient German language skills

Controls:

* Not diagnosed with Pedophilia (or other psychiatric illnesses)
* Sufficient German language skills

Exclusion Criteria:

Patients

* Prior head injury with loss of consciousness for at least 5 min
* Neurological diagnosis (including epilepsy) or prior medical conditions with possible central nervous system sequelae
* Metallic implants inside the brain or any electrical medical device (e.g. pacemaker) in the body
* Visual or hearing impairment, to the extent that it interferes with task instructions

Current medication in patients (antiandrogenic medication among the pedophilic subjects, in particular) will be recorded and acknowledged as a covariate.

Controls

* Prior head injury with loss of consciousness for at least 5 min
* Neurological diagnosis (including epilepsy) or prior medical conditions with possible central nervous system sequelae
* Metallic implants inside the brain or any electrical medical device (e.g. pacemaker) in the body
* Visual or hearing impairment, to the extent that it interferes with task instructions
* Current or previous pedophilic sexual interest

For both groups further exclusion (prematurely) will occur if initial data shows that participants don't comply with instructions or if questionnaires hint toward a lack of sexual interest in general.