From Attention to Behavior: Increasing Behavioral Inhibition (tDCS)

University of Zurich (UZH)

Status: Unknown

Conditions: Pedophilia

Treatments: Device: Transcranial Direct Current Stimulation

Study type: Interventional

Funder types: Other

Identifiers

NCT03825627

2018-02028

Details and patient eligibility

About

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.

Full description

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.

Enrollment: 76 estimated patients

Sex: Male

Ages: 18 to 65 years old

Volunteers: Accepts Healthy Volunteers

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.

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Double Blind

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76 participants in 4 patient groups

Antisaccade Task (active tDCS)

Active Comparator group

Description:

During the antisaccade task, the investigators will show participants computer-generated images depicting clothed and sexually relevant (nude) children, young adults and adults of both genders. Images will be drawn from the Virtual People Set and the Not-Real-People Set (Pacific Psychological Assessment Corporation, 2004). Pedophilic participants are expected to show a sexual preference towards a prepubescent body scheme whereas stimuli displaying adolescence and adulthood (sexual maturity) are expected to be sexually preferred by the teleiophilic control participants. In this arm active Transcranial Direct Current Stimulation will be used to influence performance.

Treatment:

Device: Transcranial Direct Current Stimulation

Antisaccade Task (sham tDCS)

Sham Comparator group

Description:

During the antisaccade task, the investigators will show participants computer-generated images depicting clothed and sexually relevant (nude) children, young adults and adults of both genders. Images will be drawn from the Virtual People Set and the Not-Real-People Set (Pacific Psychological Assessment Corporation, 2004). Pedophilic participants are expected to show a sexual preference towards a prepubescent body scheme whereas stimuli displaying adolescence and adulthood (sexual maturity) are expected to be sexually preferred by the teleiophilic control participants. In this arm sham Transcranial Direct Current Stimulation will be used during the task.

Treatment:

Device: Transcranial Direct Current Stimulation

Approach Avoidance Task (active tDCS)

Active Comparator group

Description:

During the Approach-Avoidance Task (AAT), participants will look at a series of images depicting children and adults wearing swimsuits. The images were sampled from internet advertisements and do not constitute legally objectionable material. When sourcing the images, rigorous attention was paid to meet the criteria for fair use indicated by the American Psychological Association. There are 160 images in total. Half of the images will be used in the active and the other half in the sham condition (i.e., 20 female adults, 20 female children, 20 male adults, and 20 male children per condition). In this arm active Transcranial Direct Current Stimulation will be used to influence performance.

Treatment:

Device: Transcranial Direct Current Stimulation

Approach Avoidance Task (sham tDCS)

Sham Comparator group

Description:

During the Approach-Avoidance Task (AAT), participants will look at a series of images depicting children and adults wearing swimsuits. The images were sampled from internet advertisements and do not constitute legally objectionable material. When sourcing the images, rigorous attention was paid to meet the criteria for fair use indicated by the American Psychological Association. There are 160 images in total. Half of the images will be used in the active and the other half in the sham condition (i.e., 20 female adults, 20 female children, 20 male adults, and 20 male children per condition). In this arm sham Transcranial Direct Current Stimulation will be used during the task.

Treatment:

Device: Transcranial Direct Current Stimulation